WoodWorks Shearwalls USA – Change History
This
document provides descriptions of all new features, bug fixes, and other
changes made to the USA version of the WoodWorks Shearwalls program since Shearwalls
2000.
The most
recent major version is Shearwalls 2023, released in December 2022. The most recent Sheawalls update is Version 13.1.2, released on June 28, 2024.
This file
last updated with changes on Dec 10, 2024.
Click on the links below to go to the changes for the corresponding release.
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Shearwalls 10.1 – WW 10, SR-1 |
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Shearwalls
10.21 – WW 10, SR-2a |
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Shearwalls
10.2 – WW 10, SR-2 |
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Shearwalls
13.1.2 – June 28, 2024
This update
was released to correct a problem with Shearwalls CAD drawing import that was
introduced with version 13.1.1. Due to a licensing issue with a Shearwalls
component, it was not possible to import a .pdf file drawing. This was
corrected with 13.1.2.
Shearwalls 13.1.1 – June 10, 2024
This update
was released to correct some problems with the implementation of the features
introduced in Version 13.1. A full list of these changes is not yet
available.
Shearwalls 13.1 – March 8,
2024
This version provided and provided several new features along with numerous bug fixes and small improvements. Refer to the WoodWorks Shearwalls Help for full descriptions of the following features:
- The program now includes proprietary or non-wood shear resisting elements.
- Control of amount of dead load to be distributed to shear wall end chords
- Maximum of 7 levels rather than 6 to allow you to model rooftop structures
- Ability to reposition Plan view drawing (panning) with right mouse button drag.
- Zooming via the mouse wheel in Plan view and Elevation view.
Also,
- The implementation of SDPWS provision Vertical Distribution of SFRS Strength (SDPWS 4.1.8) was corrected. The calculation of the shear force on the weak story used only the shear force due to the building mass on that level, when it should have been using the accumulated shear force from the building mass on that level and those above. For this reason, when a weak story was encountered, the program invariably determined that it passed the Exception that states that the SFRS is permitted, when it may not pass the Exception.
A full list of changes including bug fixes and minor improvements is not yet available.
Previous Versions
Note that an asterisk (*) beside any
item in the list of previous releases below indicates that the item was added
to the version history record after that version was released.
Shearwalls 2023 (Version
13) – December 22, 2022
Shearwalls
2023 is a major release which updates the Special Design Provisions for Wind
and Seismic (SDPWS) from SDPWS 2015 to SDPWS 2021.
Refer to
the WoodWorks
Shearwalls Help for
descriptions of the changes needed to update the SDPWS and other improvements
to the program.
All other
topics in the Online Help have been updated to conform to the current operation
of the program.
A full
list of changes including bug fixes and minor improvements is not yet
available.
Shearwalls 2019, Update 3
(Version 12.3) – July 14, 2021
1. Association between Sheathing Capacity and Nail Spacing (Bug 3662)
For Version 12.2, the program mistakenly included a 5” nail spacing input choice, causing a mis-association between input nail spacing and the sheathing capacities from SDPWS table 4.3A. For 5” nails sizes and less, the program used the capacity for the next lowest nail spacing listed in the SDPWS. For 6” nail sizes, there was no problem.
There are also cases, likely for 2” spacing, where the program cannot identify the capacity associated with the spacing and creates zero capacity, and sometimes assigning zero loads to a shearline with such walls. Also, the association between the wall and special adjustments and design notes from SDPWS that depend on spacing was altered.
These problems have been corrected by removing the 5” size.
Shearwalls 2019, Update 2 (Version 12.2) – June 22, 2021
1. Perforated Wall Co Factor for Narrow
Segments when Ignoring Gypsum Contribution (Bug 3596)
Starting
with version 11.0, in the calculation of the adjustment factor Co
for perforated walls from SDPWS 4.3.3.5, when gypsum wallboard is on one or
both sides the program considered narrow segments with aspect ratios between
2.0 and 3.5 as non-full-height segments even when the relevant design setting
for ignoring the effect of non-wood-panels was selected and these segments can
be considered shear-resisting segments.
Co
is used to reduce the shear wall resistance, and to increase the hold-down and
drag strut forces at the ends of these walls.
This
happened for both wind and seismic design, and regardless of whether the
Equation 4.3-5 or Table 4.3.3.5 was used to calculate Co.
An
example of this problem occurred for 11’8” long, 8’ high wall with a 2’8” long,
6’ high opening between 4’10” and 4’2” segments, with gypsum on one side and
structural panels on the other. The first segment had an aspect ratio of 1.86,
and the second 2.16. The setting to
ignore the contribution of non-wood-panels was selected, so both these segments
should have been included, but the one with 2.16 was discarded, as was the
adjacent opening. The program therefore calculated a Co = 1.0 factor
for walls without openings, but it should have been 0.83.
In
those cases where the program mistakenly neglected segments within the wall
rather than at the end, the Co factor could have been less than it
should be.
This problem has been corrected.
2. Long Delay in Rigid Diaphragm Seismic Design
(Bug 3602)
Starting with version 12.1, rigid diaphragm seismic design took significantly longer to run, and for larger, complex structures could hang when the Design button was pressed and eventually show Not responding in the title bar. The amount of slow-down was proportional to the number of hold-downs, so it was significant for a structure with several levels, numerous shear lines, and many segments. A structure experiencing the non-response had 4 levels, 9-11 shearlines per level and as many as 7 segments on a shear line.
This problem has been corrected.
3. Crash on Generating Low-Rise Wind Loads on Variable
Height Blocks (Bug 3625)
When low-rise
wind loads were generated on buildings in which attached blocks have a
difference of two or more in the number of levels, the program crashed. This
has been corrected.
4. Crash on Accept Design for Shearwalls Combined
with Non-Shearwalls (Bug 3635)
For
structures that have interior non-shearwalls and shear walls on the same
shearline, the program crashed when the Accept Design button was pressed.
Examples
of this configuration are
-
a
line with exterior shear walls and interior non-shear walls
-
any
interior line with shear walls and non-shearwalls.
5. Wind Redesign Failure Warning Note (Bug 3624)
A
warning note under the Shear Results table for wind design that appears when
shear walls pass the initial design but fail the final design check due to
redistribution of forces was randomly appearing when it should not for roughly
25% of designs, especially for large, complex structures. When this happened, the program listed
numerous shearlines containing these walls, but ordinarily it is a rare
occurrence and affects very few walls.
It was also possible for this note not to appear when it should have.
The
design of the shear walls was not affected, and the rows in the table referred
to by the note showed the correct results. The problem occurred for both rigid
and flexible distribution, but not for seismic design, and has been corrected.
For
example, for a 4-level structure with over 70 shearlines and several walls on
each line, this warning note listed almost all shear lines although the walls
on most of these lines passed design.
6. Default Values in Site Information Output (Bug
3601)
Following a sequence of steps involving running
design, closing, reopening, and re-running design, all the information shown in
the Site Information table of the Design Results were the default values that
come with the program when first installed, rather than the ones that were set
before the design was originally run. However, the design results are correctly
based on loads generated using the user inputs and not the default values.
For
example, if 120 mph wind speed and 1000-foot ground elevation were input in the
Building Site dialog box, the output table showed 130 mph and 0 feet, the
default values instead of user input values, but 120 mph and 1000 feet were
used to generate loads.
This
has been corrected.
Shearwalls
2019, Update 1 (Version 12.1) – May 25, 2020
1. Vertical Distribution of Rigid Diaphragm Forces
a) Compounding of Accidental Eccentricity (Bug
2733)
Starting
with version 12, the vertical distribution of rigid-diaphragm shear force
amplified the torsional effect of accidental eccentricities on lower levels,
such that as you moved down the structure,
the sum of the shear line forces on a level was increasingly larger than
the total of the shear loads from that level and those above. These quantities
should be equal apart from the effect of taking the worst-case of positive and
negative accidental eccentricities on each level. This effect is usually small,
creating shearline forces typically 10% greater than the applied shear force,
but the compounding of eccentricities created shear forces much larger than applied
loads, and an overly conservative design.
This compounding
occurred because the shearline forces created using the effect of accidental
eccentricity were applied to the level below and used to determine torsions on
that level, so that effectively the center of mass from the upper level was
shifted by the accidental eccentricity n-1 times at the base of an n-level
structure, when it should only be shifted once.
This has
been corrected.
b) Vertical Transfer of Rigid Diaphragm Forces for
Cantilevered Diaphragms (Bug 3526)
For all
wind and seismic design cases except Directional Method Case 2 wind loads, the
program applied the shear line forces from flexible diaphragm analysis on the
level above to rigid diaphragm torsional analysis on the level below. This was intended as a convenient way to apply the
total loading on the level above at its center of loading to the level below, but can be inaccurate in the case of
cantilevered diaphragms such as occur at roof overhangs and where perimeter
walls are non-shear walls.
The
program now directly applies the total vertically accumulated load from the
levels above at the centroid of these loads to the level below, for all design
cases. Refer to the on-line Help for a derivation of this methodology.
Note
that SDPWS 4.5.5.2 requires diaphragms to be modelled as rigid or semi-rigid
for open-front structures, i.e. those with significantly cantilevered
diaphragms, and the improvement will affect these buildings.
c) Transfer of Torsional Moment Due to Variable
Accidental Eccentricity (Bug 3543)
The
method that was used to transfer the torsional moment for rigid diaphragm
analysis downwards between levels by applying the upper level force at the
center of mass of that force to the level below, assumes that the accidental
eccentricities (ae) are the same on each level, however ae's can be different due to a different
building width on adjacent levels, or for seismic design, due to different
torsional amplification factors Ax from ASCE 7 12.8.4.3. This could lead to an inaccuracy in the
torsional analysis used to distribute the seismic forces to shear lines on the
lower level.
This has
been corrected by applying an effective accidental eccentricity on the level
below equal to (aeu*Fu + ael*Fl) /
(Fu + Fl), where aeu and ael are
the design code mandated ae's on the upper and lower level, and Fu
and Fl are the total forces from loads applied on each level. Refer
to the Online Help topics on the vertical distribution of rigid diaphragm shear
force for a derivation of this adjustment.
In the
Torsional Analysis Details output, when this occurs, a line is added to give
the effective accidental eccentricity and the adjustment equation. The line showing
the total force F used for torsional analysis on the level now shows the value
of Fl, the force from loads only on that level. This appears regardless of
whether differing ae's exist, as it is useful information at any time.
This
issue affects seismic analysis and all-heights wind analysis, as these are the
design cases with accidental eccentricities.
To gauge
the impact of the change:
For the
case of variable ae due to building width D:
Case 1 -
A penthouse on the upper level, assuming that the mass per unit foot is the
same as on the lower level. The maximum difference occurs when the penthouse is
41% of the lower level width, where the effective ae is 60% of the regular ae.
Case 2 -
A 6-story tower where five upper stories are narrow, supported by a podium base
that is 3 times the width of the tower. The effective ae is roughly half the
regular ae.
Case 3-
A building shaped like an inverted pyramid. Such a building would be very non-conservative
in that the additional width in two dimensions would not be accounted for on
the level below. Such buildings are rare but exist.
For the
case of variable ae due to differing Ax:
Case 4 -
Adjacent levels, one with Ax at maximum = 3, the other with no Ax
= 1, otherwise identical. The effective ae on the lower level is twice the
ordinary ae. Although not realistic, this serves as a limit to the effect for a
2-storey structure.
Case 5 -
Adjacent levels, one with Ax that defines the extreme torsional irregularity 1b
= 1.36, the other Ax = 1. The effective ae is 18% larger than the
regular ae.
Case 6 -
5 irregular stories on top of a regular base, which could easily happen if the
upper levels have openings on one side.
If the Ax on the upper levels is 1.3, the effective ae on the
base is 1.25 times the regular ae.
2. Torsional Amplification Factor Ax
and Torsional Irregularities
The below changes pertain to the torsional
amplification factor Ax from ASCE 12.8.4.3 that is applied to
accidental eccentricity for torsional analysis and to the determination of
Torsional Irregularity from Table 12.3-1.
a) Torsional Irregularity Exemption to Accidental
Eccentricity by Structure vs. Level (Bug 3546)
The
program was applying the stipulation
introduced in ASCE 7-16 12.4.8.2 that accidental eccentricities be applied only
in the presence of torsional irregularities on a level-by-level basis, so that
some levels could include the 5% extra eccentricity and some not. However, accidental eccentricity is now
applied on each level if a torsional irregularity exists anywhere on the
structure, because
- 12.8.4.3 says that “Structures … where a torsional irregularity exists … by multiplying Mta [the accidental torsional moment] at each level….[by Ax, the torsional sensitivity factor]. Mta would have to exist on each level for it to be multiplied on each level.
- Commentary 12.8.4.3 says that the amplification of accidental eccentricity is a “system level phenomenon … not explicitly related to an individual story”
- The Commentary to 12.4.8.2 regarding accidental torsion refers to “Irregular structures” in several places, not irregular levels.
This was a non-conservative error where it occurred. It could be particularly large for a base level of a structure with a small difference in displacements, with torsionally sensitive levels above, due for example to openings on one side of the upper levels.
b) Displacement used for Ax Factor (Bug
3521)
When
calculating Ax the program was using shear wall defections on the
level x only, but according to Commentary C12.8.4.3, introduced ASCE 7-16, they
should be the cumulative lateral displacements from the base of the structure up
to and including level x. Shearwalls now
uses these deflections.
The
factor Ax is calculated using displacements δ on extreme perimeter shear walls on
each level of the structure, where Ax = (δmax / 1.2 δavg)2. It applies only to Seismic
Design Categories C-F. 12.8.4.3 also says that Ax is a “system level phenomenon
… not explicitly related to an individual story”
Note
that when determining torsional irregularities from Table 11.3-1 via a similar
procedure, the per-story deflections are used, also according to C12.8.4.3.
The use
of story displacements was conservative for levels with large differences in
displacements that have levels with less of a disparity below, or levels below
whose torsional characteristics are reversed. It will be non-conservative for
levels that have levels below that are more have a greater difference in
deflections.
Note
that the probability of a large error is made smaller by the fact that the
shearline forces responsible for the deflections are transferred from the upper
levels to the lower and contribute to the calculation of Ax on the
lower level,.
c) Hold-down Forces Used to Determine
Displacements for Ax and Torsional Irregularities (Bug 3351)
In
detecting Torsional Irregularities or calculating Ax, the program was using
hold-down forces derived from the worst case of positive or negative accidental
eccentricities to calculate the displacements used for both the positive and
negative eccentricities. The effect of this was to increase the lesser of the
deflections and reduce the difference in displacements that creates torsional
irregularity or a larger Ax.
This has
been corrected, and hold, down forces are calculated for the positive and
negative eccentricities independently for the purpose of calculating Ax and
irregularity.
d) Ax Factor and Torsional Irregularity
Determination in Design Iterations (Bug 3547)
The
following changes have been made to the implementation of the of the torsional
amplification factor Ax from ASCE 12.8.4.3 .and the determination of
Torsional Irregularity from Table 12.3-1 in the iterations used in the shear
wall design process. These iterations also involve the redundancy factor ρ. (Refer to the Shearwalls Online Help
topic about Design iterations for more information on these iterations).
i. Iteration for Accidental Eccentricity Based
on Torsional Irregularity
The
program would perform a second iteration setting Ax to a value
greater than one in the determination of accidental eccentricity only if the
initial iteration determined that there was a torsional irregularity. However,
the second iteration is now always performed, for two reasons:
-
a
second iteration is necessary to implement the new provision from ASCE 7-16 12.8.4.2
that no accidental eccentricity be applied in the absence of torsional
irregularity on any level
-
the
calculation determining the existence of a torsional irregularity is not
equivalent to the calculation of Ax despite its similar mathematical
form because the displacements used are different according to C12.8.4.3, (see
Bug 3521, above).
ii. Recalculation of Ax if ρ = 1.3.
If the
program determines that the redundancy factor is 1.3 after being set to 1.0 in
the first iteration, it performs and extra design iteration with shear line forces factored by 1.3. It
then recalculates the Ax factor and determines torsional
irregularities. However, if the Ax
factor was determined to be greater than 1.0 on the first iteration, it uses
shear lines factored by Ax for the recalculation of Ax
and irregularities, when it is supposed to use Ax = 1.0 according to
ASCE 7. However, since the calculations depend on relative displacements, and Ax
is applied to all shearlines, this problem was unlikely to have much effect.
iii. Ax used for Final Design Check
Iteration
If the
redundancy factor was 1.0, and the program determined that an Ax factor
other than 1.0 needed to be applied, it applied the factor to the shear lines
and redesigned the walls. However, after that iteration, it did not recalculate
Ax based on the new walls. Therefore, the forces on the shear walls
shown in the Design Results are based on an Ax calculated for other
walls. The purpose of the final design check is to show the performance of the
designed shear walls based on forces that would be generated with those walls, but
the forces shown are generated with an Ax using possibly different
walls.
iv. Reorganization of Iterations
These
changes were implemented in a simplification of the iterations such that Ax,
ρ and torsional irregularity is recalculated after each iteration. An
initial iteration is performed with accidental eccentricity but Ax =
0, then if ρ = 1.3 another iteration is performed, then another iteration
is performed with the recalculated Ax value or the absence of accidental
eccentricity, and a final iteration to check the designed walls against a new
set of forces generated with those walls. Refer to the Online Help for more
information.
e) Intermediate Data for Ax and Irregularity
Calculations (Feature 217)
At the
end of the Torsional Analysis Details file, there are now tables showing the
intermediate data used to determine Ax = (δmax / 1.2 δavg)2 , and the ratio used to determine
torsional irregularity = δxe,max / δxe,avg ,
where δ is the structural displacement and δxe is the story drift, both of them on extreme
perimeter shear walls on each level.
These
data are shown for each level of the structure, each of the 4 force directions,
and for the cases of positive accidental eccentricity and negative accidental
eccentricity added to the torsional moment.
The table
for Torsional Irregularities shows the shear line forces used to determine
perimeter story drift (with Ax = 1.0 and 5% accidental
eccentricity), the story drift on the extreme left and right shear lines, the average of the story drifts,
and the ratio of maximum drift to average.
The table
for Ax shows the structural displacement from the base to the top of
each level for the left and right perimeter shearline, the average of the
displacements, and the Ax factor.
Each
table has notes explaining the meaning of the data and their consequences in
the ASCE provisions.
Please
note that the data shown are for the Ax and irregularities those
used to create the forces shown in the Design Result reports, which create the
deflections shown in these reports. If you were to calculate Ax
again using these deflections, the value could be slightly different, and if
this Ax were used to create new forces the process could be carried
on indefinitely.
Testing
revealed that his effect is very slight, and no Ax even 1% greater
than the previous one was generated when an extra iteration was made.
3. User-Defined Shearline Forces for Rigid
Diaphragms (Bug 3528)
User-defined
forces entered in Load Input view were being added to shearline forces already
derived from rigid diaphragm torsional analysis of applied loads, however such
forces used to model the effect of forces from adjoining structures should be
included in torsional analysis. As a message appears when Load Input view is
invoked giving this as a reason to add these forces, they are now treated as if
they were loads on the level on which they are entered and applied to the
torsional analysis.
An
exception is made when there are no applied or generated loads on the level,
only user-applied shear line forces. In this case we can assume that you do not
want to perform rigid load distribution and wish to analyze individual shear
lines with forces calculated manually.
Furthermore,
for all wind and seismic design cases except Directional Method Case 2 wind
loads, the force was transferred to the level below only if it was defined for
flexible diaphragm analysis as well as rigid. For Directional Method Case 2
wind loads, it was not transferred below at all. This inconsistency has been
corrected by this change, and if loads and direct shearline forces are both
entered on a level, the effect of the forces is transferred to the level below
as if they were loads. If only user-applied shear line forces are added, there
is no vertical transfer. Note that flexible diaphragm user-applied forces are
still transferred below in all circumstances.
4. Story Weight with Manually Added Building Area
Masses (Bug 3537)
Starting
with version 11.0, when manual area building masses were added to lines or
walls in both the E-W and N-S directions, the story weight wx used to generate seismic loads
as per ASCE 12.8-12 was inaccurate in an unpredictable way depending on load length
and the tributary width, and could be several times higher or lower than the
weight of the input masses. The incorrect weights appeared in the base shear
distribution table of the Seismic Load Generation Details and the Seismic
Information table of the Design Results.
This
problem did not occur when manual masses were entered in just one direction.
In
a typical example of a single block of 40 x 40 feet with a gable roof with 25
psf roof self- weight and 3 manually applied 30 psf area building masses with a
tributary width of 5 feet, wx was 130,350 lbs when it should have been
62,100 lbs.
Masses
are used to generate loads in both directions, so it was possible to model all
building masses by adding them to shear lines in just one direction to avoid
this problem, however it has been corrected.
5. Large Flexible Shear Line Force Due to Repeated
Redundancy Factor (Bug 3527)
For
flexible diaphragm analysis, the program was applying the redundancy factor 1.3
from ASCE 7 12.3.4 to shear line forces twice, so that when there was
redundancy, the forces were too large by a factor of 1.3. This was happening in both force directions,
and whether redundancy was detected by the program or was entered in the Site
Dialog. Most buildings do not have a redundancy factor.
6. CAD Drawing Import Procedure (Change 89)
The CAD
Import Wizard has been improved to make it easier and more intuitive to add
drawings for multiple levels. Previously, it was unclear to some users that you
had to press Start positioning to scale the CAD drawing, and the
sequence between scaling and adding new levels could be confusing. The Wizard
now guides you through a sequence of steps for each level.
7. Simpson Hold-down Database Property Update (Change 115)
The properties of Simpson hold-downs in the database included with Shearwalls have been updated to conform to the 2019-2020 Catalogue. Previously, the properties from the 2015-2016 Catalogue were in use.
8. Impact Resistant vs. Operable Windows for
Enclosure Calculations (Bug 3508)
The program included an "Impact
resistant" check box in the Opening input view, in order that the opening
not be included in enclosure calculations from ASCE 7 26.12. This was based on
ASCE 7-98 6.5.9.3; however, it was dropped for ASCE 7-05, but the program was
not changed.
The Commentary to 6.5.9 says only
"operable" windows are to be included in Enclosure calculations, and
this is still in C26.12, but was never implemented in the program, so the name
of the "Impact resistant" checkbox is now changed to
"Non-operable" and has the same effect. .
9. Program Operation
The
following problems related to specific user interface operations have been
corrected:
a) Crash for Wind Uplift or Dead Loads with
Vertical Shearline Offsets (Bug 3518)
The
program crashed upon adding dead or wind uplift load to shearlines that had
vertical offsets between levels, i.e. a shearline with no walls below it. This
has been corrected.
b) Crash when Gypsum Sheathing is Designated OSB (Bug
3519)
In the
wall input form, if the OSB checkbox is set for a wood structural panel
sheathing side and then the material is set to a gypsum-based material, the
program would crash upon running design. This has been corrected.
c) Screen Message upon Change of Gypsum Fastener Length
(Bug 3529)
d) Crash upon Missing Wall Stud Database File (Bug
3529)
If a wall stud database file used in a
Shearwalls project was no longer in your installation or no longer referenced
by the database.ini file as being included in the program, the program would
show a blank Framing Material in wall input view, and eventually crash upon
design if an available material was not selected in its place. The program now outputs a warning and selects
an available material if it detects this condition.
Shearwalls 2019 (Version 12.0)
– December 16, 2019
Important:
WoodWorks
released a Version 11.2 at the same time as Shearwalls 2019 in order that important
corrections and other changes are included in a version that implements the
previous design codes and standards.
Most
bug fixes and small changes appearing for the first time in Shearwalls 2019 are
listed under Version 11.2,
below. Please consider both lists as the record of changes for Shearwalls 2019.
Shearwalls 2019 (Version 12.0)
B. Update to ASCE 7-16 – Seismic Load Generation and
Design (Feature 239)
C. Update to ASCE 7-16 – Wind Load Generation (Feature
239)
D. Force-transfer Walls (Feature 33)
F. Load Generation and Force Distribution
Shearwalls 11.2 – Date – Design Office 11.2
B. Load Generation and Force Distribution
C. Building Model and Graphics
1. Update to IBC 2018
The program has been updated to
conform to the 2018 International Building Code from the 2015 IBC.
No provisions are taken directly
from IBC, but the IBC 2018 references the Special Wind Provisions for Wind and
Seismic (SDPWS 2015) and the ASCE 7-16 design loads standard, both of which are
implemented in Shearwalls 2019. The load combinations used by Shearwalls that
are published in both the IBC and ASCE 7 have not changed.
The
references to the edition of the IBC in the Welcome box, Building
Codes box, About Shearwalls box, and the Design Results, Seismic
Load Generation Details, Wind Load Generation Details, and Torsional Analysis
Details output reports have been updated to 2018.
2. Update to ASCE 7-16
The program has been updated to conform to the
2016 ASCE 7 Minimum Design Loads for Buildings and Other Structures from
the 2010 ASCE 7.
Refer to B. Update to ASCE 7-16 – Seismic Load
Generation and Design (Feature 239) and
C. Update to ASCE 7-16 – Wind Load Generation
(Feature 239) for the program changes
corresponding to changes in design standard provisions.
The references to
the edition of the ASCE 7 in the Welcome box, Building Codes box,
About Shearwalls box, and the Design Results, Seismic Load Generation
Details and Wind Load Generation Details output reports have been updated to
ASCE 7-16.
3. Update to NDS 2018
The program has been updated to
conform the 2018 National Design Specification for Wood Construction (NDS) and
the 2018 NDS Supplement, from the 2015 NDS and Supplement. NDS 2018 is
referenced from the 2018 IBC.
The
reference to the edition of the NDS in the Building
Codes box that is accessed from the Welcome box has been updated to 2018, and the links in the Help menu to the on-line edition of the NDS and
Supplement lead to the 2018 editions.
The limited number of procedures in
Shearwalls which come directly from the NDS, such as bolt elongation and nail
withdrawal, have not changed for the 2018 edition.
B. Update to ASCE 7-16 – Seismic Load Generation and Design (Feature 239)
Please note that some of the items in this section
describe changes to the program that came about because of the analysis of ASCE
7-16 as compared to ASCE 7-10 but were not directly due to changes in the design
standard. These items are indicated with an asterisk (*).
1. Site Classes and Site Coefficients (7-10 11.4.2 and 11.4.3, 7-16 11.4.3 and 11.4.4)
These changes pertain to the definition of Site Classes A-F and their use in determining site coefficients Fa and Fv via tables 11.4-2 and 11.4-1, which also depend on the mapped response acceleration parameters Ss and S1, respectively. Fa and Fv are then multiplied by SS and S1 to arrive at spectral response acceleration parameters SMS and SM1, which are then multiplied 2/3 to get design parameters SDS and SD1 , which contribute to the determination of the Seismic Design Category (11.6) , base shear V (12.8), vertical seismic effect (12.4.2.2), min. and max. diaphragm design forces (12.10.1.1), and wall out-of-plane (12.11.1) and anchorage (12.11.2) forces.
a) Change in Standard
i. Min Fa for Default Use of Site Class D
If Site Class D is used as the default site class because soil properties are not known, as per 11.4.3, then a minimum value of 1.2 is now applied to Fa as per 11.4.4. This applies to SS = 1.0, 1.25, or 1.5.
ii. Fa and Fv for Class B when Velocity Measurements not Made
If Site Class B is determined through rock conditions (using Chapter 20 – Site Classification Procedure), but velocity measurements were not made, Fa and Fv are now to be set to 1.0.
iii. Table 11.4-1, Short-Period Site Coefficient Fa
In Table 11.4-1 for Fa,
- The last column was for Ss greater than or equal to 1.25, but now a new column has been added for Ss greater than or equal to 1.5
- The values for Site class B have all been reduced from 1.0 to 0.9
- The values for Site class C have increased 0.1, except for Ss = 1.25 which has increased 0.2
- The values for Site class E have increased 0.1 for SS <= 0.25 and SS = 0.75
- No values are provided for Class E for SS = 1.0 or greater (3 columns), as section 11.4.8 now says that site-specific analysis is required for them. Refer to 2.a)iii below for an exception to this and the values used in that case.
iv. Table 11.4-2, Long-Period Site Coefficient Fv
The last column was for S1 greater than or equal to 0.5, but now a new column has been added for S1 greater than or equal to 0.6
- The values for Site class B have all been reduced from 1.0 to 0.8
- All values for Site class C except for S1 = 0.3 have decreased by 0.1 or 0.2.
- All values for Site class D except for S1 <= 0.1 have increased by 0.2 or 0.3.
- For all Class D except for S1 <= 0.1 (5 columns), a note a refers to 11.4.8 for conditions under which ground motion analysis must be done instead of using the tabulated value. Refer to 2.a)iv below.
- No values were provided for Class E for S1 = 0.2 or greater (5 columns), as section 11.4.8 says that site specific analysis is required for them. However, refer to 2.a)v below for an exception to this and the values used for that exception.
- The sole remaining value for Site class E, S1 <= 0.1, has increased from 3.5 to 4.2.
b) Min Fa for Default Use of Site Class D
As
it is now possible to use site-specific procedures and enter your own Fa
for class D (see 2.c) below), the program will not restrict Fa to 1.0 if you do so. It is possible that
ground motions are determined rigorously but soil profiles are not.
c) Fa and Fv for Class B when Velocity Measurements not Made
A checkbox has been added to the Site
Information dialog called No
velocity measurements. It is
active for Site Class B, only and is unchecked by default. If checked, the program
will set Fa and Fv to one.
As it is now possible to use
site-specific procedures and enter your own Fa and Fv for
class B (see 2.c)
below), the program will not restrict Fa
and Fv to 1.0 if you do so, as it is possible that velocity
measurements are not taken but 21.2 Risk-targeted Hazard Analysis is
used for Fa and Fv.
d) Table 11.4-1, Short-Period Site Coefficient Fa
Table 11.4-1 values have been modified to those in ASCE 7-16. A new column for SS greater than or equal to 1.5 has been added and the table interpolation modified accordingly.
For site class E and SS
greater than 0.75, the input of Fa in the Site dialog is active, as
described in 2.c)i
below . Note that this starts at 0.75 rather
than 1.0 because interpolation is not possible between 0.75 and 1.0 with no
tabulated value for 1.0.
e) Table 11.4-2, Long-Period Site Coefficient Fv
Table 11.4-2 values have been modified to those in ASCE 7-16. A new column for S1 greater than or equal to 0.6 has been added and the table interpolation modified accordingly.
For site class E and S1
greater than 0.2, the values shown in the Fv input are given in 2.a)v below,
and the operation of this input is described 2.f)
below. .
Refer to 2.e)
below input of values when ground
motion analysis must be done for class D as per note a.
2. Site-specific Ground Motion Procedures (7-10 11.4.7, 7-16 11.4.8)
This section pertains to the conditions under which site-specific ground motion analysis must be done to determine the site coefficients Fa and Fv rather than using the tabulated values described in item 1 above. Note that for both ASCE 7-10 and ASCE 7-16, using ground motion analysis is permitted for any structure, but Shearwalls only allowed it when it was required.
a) Change in Standard
i. Required Site-specific Procedures for Site F
For site F, the reference to site-specific ground motion
procedures in 21.0 has been changed site response analysis in 21.1 (as opposed
to also including ground motion hazard analysis in 21.2).
ii. Cases Requiring Ground Motion Analysis
The following cases now require ground motion hazard analysis from 21.2 rather than using the tabulated values of Fa and Fv.
Seismically Isolated or Damped Structures (S1 >= 0.6)
Seismically isolated or damped structures with S1 greater than or equal to 0.6. This requirement was also in ASCE 7-10.
Class E, Ss >= 1.0
This clause says that the analysis is required for Ss => 1.0, but because there is no value for Fa for Ss = 1.0 for interpolation, it is needed for Ss > 0.75, unless Exception 1 (below) is used. Previously ground motion analysis was not required for Class E.
Class D, S1 >= 0.2
For site class D, the analysis is required for Fv if S1 >= 0.2 unless the Exception 2 (below) is used. Previously ground motion analysis was not required for Class D.
Class E, S1 >= 0.2
For site class E, the analysis is required for Fv if S1 >= 0.2 unless the Exception 3 (below) is used. Previously ground motion analysis was not required for Class E.
iii. Exception 1 for Ss and Class E
For Class E, Class C coefficients can be used in lieu of ground motion hazard analysis.
iv. Exception 2 for S1 and Class D
The following conditions apply when Site Class D is used with S1=> 0.2 to avoid site specific analysis:
- For T <= 1.5 TS, the seismic response coefficient CS must be calculated with 12.8-2, with TS defined as SD1/SDS. , As 12.8-2 is the usual procedure, presumably this means that the maximum CS from 12.8-3 cannot be applied. Maximum Cs is only used when T >= Ts, so that this applies in the range T = TS to 1.5 TS. This range is within the range of structures possible in Shearwalls, but not commonly encountered, so that ordinarily, tabulated values will be used with Cs from 12.8-2 that is below the maximum.
- For TL >=T > 1.5TS, 1.5 times the maximum CS given in Eq’n 12.8.3 must be used. This range is at about the limit of what can occur in Shearwalls but could be more likely to happen in some locations.
- For T > TL, 1.5 times the maximum Cs given in Eq’n 12.8.4 must be used. TL is the long-term period given in maps 22.14-17. The lowest period in these maps is 4s, far beyond what is encountered in Shearwalls, so this range does not apply.
v. Exception 3 for S1 and Class E
If Site Class E is used with S1 => 0.2, you can avoid site specific analysis for if the period T is less than or equal to TS, which it ordinarily is in Shearwalls. The ASCE 7-16 does not include tabulated values for S1 and Class E, but ASCE provided us with coefficients to use that will appear in the next ASCE supplement. They are Fv (0.2) = 3.3, Fv (0.3) = 2.8, Fv (0.4) = 2.4, Fv (0.5) = 2.2, Fv (0.6) = 2.0.
b) Site Class F
When Site Class F is chosen:
i. Required Site-specific Procedures*
At the bottom of the Site Information section of the Seismic Load Generation Details file, a note now appears saying that site response analysis from 21.1 is needed.
ii. Default Values*
When Class F is selected in the Site Information dialog, the default value is no longer what was in the previous entry for the other site classes; instead the program places 0.0 in the input. If it is not changed, you are prompted to enter a value.
Shearwalls now allows you to override the tabulated values for Fa and for Fv for the permitted use of coefficients from ground motion analysis on any structure, or their required use on seismically isolated or damped structures.
Two checkboxes called Use site-specific ground motion procedures in the Site Information dialog allow you to override the tabulated values for Fa and for Fv
For Site Class F, they are always inactive and checked, and the Fa and Fv boxes are active, as is currently the case.
For Site Classes A-E, the checkboxes are active and unchecked by default, and Fa and Fv are inactive. If they are checked, then the Fa and Fv values become active and show values from the Tables 11.4-1 and 11.4-2, and you may modify these values.
ii. Output
If ground motion analysis was not required for Fa
and/or Fv according to 11.4.8, but you decided to use it for either
or both, a note appears under the Site Information section of the Seismic Load
Generation Details indicating site-specific
ground motion hazard analysis from ASCE 21.2 was used.
If ground motion analysis was required for Fa and/or Fv unless the Exceptions 1-3 are invoked, and you decided to forego the Exceptions and enter an Fa and/or Fv, the same note appears except that it says the analysis is “required” rather than “used”.
d) Seismically Isolated or Damped Structures with S1 >= 0.6
No changes were made specifically to implement seismically isolated or damped structures with S1 >= 0.6. If you have such a structure, then you check the Use site-specific ground motion procedures box for Fv and enter the result of your site-specific analysis.
e) Exception 1 for Ss and Class E
To implement Exception 1, the value in the Fa input for Class E for Ss > 0.75 is set to that for Class C. This can be over-ridden by selecting the checkbox for site specific analysis and entering a different value.
f) Exception 2 for S1 and Class D
For site class D and S1 >= 0.2, if the site-specific ground motion checkbox is unchecked upon load generation, for each direction:
- if Ts < T < = 1.5 Ts, the program does not apply the maximum CS from Eqn. 12.8-3 when determining base shear V, always using Eqn. 12.8-2. The value shown as the maximum value in the Seismic Load Generation Details table is from 12.8-2.
- if T > 1.5 Ts, the program will apply 1.5 times the maximum CS rather than the calculated maximum when determining base shear V. The calculated and maximum values from Eqns. 12.8-2 and 12.8-3 are still shown in the table, and the Cs value shown is 1.5 times the maximum value.
Notes appear below the table in the Seismic Load Generation Details indicating that the exception was applied in the direction or directions, and that max CS was not applied for T <= 1.5 Ts, or that 1.5 max CS was applied for T>1.5Ts
g) Exception 3 for S1 and Site Class E
For site class E and S1 >= 0.2 the values shown in Fv are those supplied by ASCE (see 2.a)v below), If T > Ts, then the site-specific ground motion checkbox is always checked and disabled, and you must enter Fv as per Exception 3.
3. Application of Redundancy Factor (12.3.4.1)
a) Change in Standard
12.3.4.1 now refers to the minimum and maximum diaphragm forces from Eqns. 12.10-2 and 12.10-3 when listing all those design provisions for which redundancy factor ρ = 1. Previously it referred only the diaphragm force Fpx from Eqn. 12.10-1
b) Drag Strut Force Calculation
The only application of Fpx in Shearwalls is for drag strut forces, and the program was already setting ρ = 1 when evaluating Eqns. 12.10-2 and 12.10-3 for them. However, the following small inaccuracies in the Design Results were noticed and corrected:
i. Seismic Information Table Note*
In reference to the application of the redundancy factor under the Seismic Information table now refers to the diaphragm force Fpx as well as the drag strut forces.
This is because drag strut forces can be based on the design shear force factored by ρ if it is greater than the diaphragm force, according to 12.10.2 and 12.10.1.1.
ii. Drag Strut Table Legend*
In the drag strut table legend, the phrase
Includes redundancy factor rho.
has been removed from the definition of shearline force for perforated walls.
4. Maximum SDS Value in the Determination of Cs and Ev (12.8.1.3)
a) Change in Standard
i. Limit on SDS v. SS
Previously, the value of SS, the short-term mapped seismic response acceleration parameter, was permitted to be limited to 1.5 for certain design procedures and under certain conditions. Now there is a limit on SDS, the short-term design response acceleration parameter, of the greater of 1.0 and 0.7 times the calculated SDS. As these parameters are related by SDS = 2/3 Fa Ss, the old limitation was equivalent to SDS <= Fa, so this represents a substantive change.
According to the values of Fa in Table 11.4-1, SDS is greater than 1.0 for Site Class C and SS >= 1.25, and for Site Class D with SS greater than 1.5. These are common Site Classes, and SS can be as high as 2.0 in earthquake- prone regions of the USA. This limitation will come into play in many circumstances.
ii. Relevant Applications of SDS
Previously this limitation was applied to the calculation of seismic response coefficient CS in Eqn. 12.8-2 and its lower limit in 12.8-3. CS is multiplied by the building weight to arrive at base shear V.
It is still applied in these places, but now also to the calculation of SDS for vertical earthquake load determination in Eqn. 12.4-4a, which is Ev = 0.2 SDS D, where D is dead load.
The limit on the value of SDS is still not applied to the Seismic Design Category (11.6), min. and max. diaphragm design forces (12.10.1.1), and wall out-of-plane (12.11.1) and anchorage (12.11.2) forces. In addition, it is not applied to SDS in the calculation of TS for the new Exception 2 to the use of site-specific ground motion analysis for Site Class D (11.4.8).
iii. Acceptable Criteria
The following criteria to be met for use of this limit were in ASCE 7-10 and are still to be applied:
- Building is 5 storeys or less
- Building has a fundamental period, T = 0.5 s or less
The following criteria are new to ASCE 7-16
- No irregularities
- Site Class A-D (not E or F)
- Redundancy factor is 1.0 (not 1.3)
- Risk category I and II
b) Value of Limit on SDS vs. SS for Calculation of CS
The program now applies a limit of the greater of 1.0 and 0.7 times the calculated SDS to the value of SDS used for CS = SDS / (R/Ie), and to the lower limit CS = 0.044 SDS Ie. Previously, the SS value in determining SDS was limited to 1.5.
c) Application to Ev
The limit now applies to the SDS calculation of the vertical seismic force component of hold-down forces, Ev = 0.2 SDS D
i. Effect of New Criteria
As the building can be irregular or have a redundancy factor in one direction but not the other, the limit can be applied to hold-downs in one force direction but not the other.
As it can be torsionally irregular for rigid diaphragms but not flexible, the limit can be applied for flexible diaphragms but not rigid.
ii. Plan View Legend
In the Plan View legend explaining the Ev force, the SDS shown is now the limited one, and the program now shows SDS values for both force directions in the unusual case that they are different. This can now be different for rigid and flexible diaphragm design.
iii. Seismic Information Table
In the note under the Seismic Information table of the Design Results explaining the Ev force, the SDS shown is now the limited one, and the program now separate notes for both force directions in the unusual case that they are different. This can now be different for rigid and flexible diaphragm design.
d) Implementation of Acceptable Criteria
i. Risk Category
The limit on SDS is no longer applied to buildings in Risk Category III (Hazardous) or Risk Category III (Essential).
ii. Site Class
The limit on SDS is no longer applied to buildings in Site Classes E and F.
As seismic load generation is performed before shear walls are designed and irregularities can be detected, the program relies on the new user input of irregularities in the Site Information dialog (see D below) to determine whether the structure limit cannot be applied because the structure is irregular. If you are performing both rigid diaphragm design , if any irregularity is entered, the limit on SDS is suppressed. If only flexible diaphragm design is set to be performed, it is suppressed for any irregularity except horizontal Torsional irregularities 1a and 1b.
As the program is able to detect torsional irregularities and Horizontal Irregularity 4 – Out-Of Plane Offset, if during shear wall design these irregularities are detected but hadn’t been entered in the Site Information, or vice-versa, and if the SDS value used for CS would have been different as a result, a message appears suggesting that you reset the irregularity selections and rerun the load generation and design.
If the only irregularity set in the Site information is a torsional irregularity, and a limit that would have been imposed on SDS is suppressed, a message appears suggesting that you run load generation and design on rigid and flexible diaphragms separately. This allows the limit on SDS to be applied for flexible diaphragm design while using the calculated SDS for rigid diaphragm design.
iv. Redundancy Factor ρ
For the purpose of calculating Cs for base shear V, the limit on SDS is applied if 1.0 or Calculate is set in the Site Information dialog for the Redundancy Factor ρ. For the purpose of the vertical seismic component Ev of hold-down forces the limit is applied if ρ is set to 1.0 or the program calculates ρ = 1.0 for the force direction.
If Calculate was set and ρ = 1.3 was calculated by the program, a message appears suggesting you set ρ to 1.3 and regenerate loads. If this happens only for rigid or for flexible diaphragm design, the message suggests running load generation and design for these cases separately.
e) Output
In the Seismic Load Generation Details output, in the note referring to the applicability of the two SDS values shown,
i. References to Ss and Ev
The note no longer refers to SS and includes Ev among the calculations that are limited.
ii. Non-limited Applications*
The note now also includes diaphragm design force limits and out-of-plane forces those design procedures that are not limited. Previously it mentioned only the Seismic Design Category.
5. Accidental Torsion for Rigid Diaphragm Analysis (12.8.4.2)
a) Change in Standard
The requirement that an accidental torsion of 5% of the building width be added to torsional analysis for rigid diaphragms has been limited to structures of Seismic Design Category B with Type 1b horizontal structural irregularity (Extreme Torsional) and SDC C-F with either Type 1a (Torsional) or Type 1b. The irregularities are defined in Table 12.3-1.
The calculation of Type 1a or Type 1b horizontal irregularities requires evaluation of the deflection at extreme shearlines derived from forces using the 5% accidental eccentricities and amplification factor Ax = 1.0. Ax is from 12.8.4.3
b) Torsional Analysis
The program already did a preliminary iteration of loads analysis and design to determine the value of redundancy factor ρ and the torsional amplification factor Ax . In that iteration the program now determines the torsional horizontal structural irregularities 1a and 1b using Ax = 1.0 Torsional irregularity 1a occurs for Ax > 1.0, and 1b occurs for Ax > (1.4/1.2)2, or equivalently when δmax / δavg is greater than 1.2 or 1.4, respectively, δmax being the largest and δavg the average of the story drifts at the endmost shear lines.
The 5% accidental eccentricity is not applied for SDC A, is applied only if there is an extreme torsional irregularity for SDC B, and only if there is a torsional irregularity for all other structures.
c) Output
In the Torsional Analysis Details file, if there is no accidental eccentricity:
- The line giving the value of accidental eccentricities eax and eay is removed
- The line giving the Torsions T does not show eax or eay being added and subtracted
The note that gave the reference to 12.8.4.2 now gives the SDC and presence or absence of torsional irregularities 1a and 1b, and if applicable indicates that it is 0 for those reasons.
The amplification factor Ax, which was only shown if greater than 1.0, is now always shown. If it is 1.0, it still does not appear in the line showing the calculation of torsion T.
6. Diaphragm Design Force (12.10.1.1)
a) Change in Standard
i. Definition of Transfer Force
The description of forces being transferred through the diaphragm via offsets or stiffness changes in shear walls has been formalized in 11.2 Definitions as a Transfer force, rather than being more briefly described in 12.10.1.1 Diaphragm Design Forces.
ii. Overstrength Factor for Transfer Forces
There is now a requirement that the transfer forces from discontinuous shearlines be increased by the overstrength factor Ω0 from 12.4.3.1 before being added to the diaphragm force.
iii. Redundancy Factor
The requirement that the redundancy factor ρ from 12.3.4 be applied to transfer forces from discontinuous has been removed. This is in accordance with items 5 and 6 in the list of conditions in 12.4.3.1 for which ρ = 1, which refer to the design of members, collector elements, connections, etc. where overstrength factor is either required or used.
Note that this is in seeming contradiction with the Commentary C12.10.1.1 which says that the redundancy factor applies to diaphragm transfer forces, but in a communication ASCE clarified that ρ and Ω0 are not to be applied simultaneously and that the Commentary applied to typically smaller transfer forces due to changes in lateral stiffness rather than Irregularity Type 4 Offsets to which Ω0 is applied.
iv. Exception for One-and Two-family Dwellings
An exception has been added indicating that for one- and two-family dwellings, the Ω = 1.0 so that overstrength is not required on transfer forces.
b) Transfer Forces
The transfer forces due to vertically discontinuous shearlines that are used for calculation of shearline forces on the level below for the purpose of drag strut force calculation have been changed as follows:
If the shearline forces from above include a redundancy factor ρ = 1.3, it is removed. The overstrength (Ω0) factor of 3.0 for bearing wall systems and 2.5 for building frame systems (from Table 12.2-1) is applied. For flexible diaphragm design, both
c) Shearline Forces for Drag Strut Design based on Diaphragm Force*
The requirement that transfer forces from discontinuous shearlines be factored for overstrength inspired a re-evaluation and reimplementation of the calculation of shearline forces used to create drag strut forces when they are based on the diaphragm design force Fpx.
i. Previous Implementation
Previously, the program determined a proportionality ratio between the diaphragm force Fpx, and the sum of the unfactored design force Fx on all levels above and including the level in question. It then multiplied each ASD-factored shearline force on that level by that factor, to convert from base-shear-based forces to Fpx-based forces. This approach was an approximate one in the following ways:
Discontinuous transfer forces
Such an approach treats discontinuous transfer forces as if they were a load due to the equivalent amount of building mass at that location, and that load is based on the diaphragm design force Fpx rather than the design shearline design force Fx.
Redundancy Factor
This approach incorporated the redundancy factor ρ, as was required by 12.10.1.1, only indirectly via its contribution to the design shearline forces that are then factored by the proportionality ratio, so that the redundancy factor was effectively modified by that ratio. The much larger Ω0 factor would make this an unacceptably large discrepancy.
User-applied Loads and Forces
Manually entered seismic loads and shearline forces were not considered in this calculation, and if they exist, they would be assumed to be based on Fpx rather than the base shear. As these may represent forces from adjoining structures, this may not have been the best approach.
Rigid Diaphragm Analysis
The assumption of a linear proportionality factor
relating diaphragm-force-based shearline forces and base-shear-based forces
does not consider torsional effects and non-linear stiffness calculations used
in rigid diaphragm analysis. That is, for rigid diaphragms, a larger diaphragm-based
force might cause a shift in distribution of forces to the shearlines that is
not considered.
ii. New Implementation
A proportionality factor between the diaphragm force Fpx and the unfactored design force Fx on the level in question is now applied to all the seismic loads that were created from building masses on the level x. The program then gathers these loads along with transfer forces from the level above, factored by Ω0, and user-applied loads and forces, and distributes them to the shearlines via rigid and flexible diaphragm distribution routines.
This shearline force represents the contribution of the loads on the level with the drag strut. The shearline forces from levels above on the same shearline are then added in (see 7.b) below), and then the maximum of this force and the force used for shear wall design is used for drag strut force calculations.
Note that the resulting drag strut design shearline forces on the level below are now included in the Design Results output (7.d) below) and shown in Plan View (see E.6 below).
d) Diaphragm Loads and Force in Plan View*
It is now possible to view the elemental loads and forces associated with the diaphragm force Fpx and the transfer forces used with Fpx in the Loads and Forces action of Plan View. Refer to E.6 below for details.
e) Exception for One-and Two-family Dwellings
The exception for one- and two-family dwellings has not been implemented in Shearwalls.
The following pertains to the output of the diaphragm force on each level and in each direction in the Seismic Information table of the Design Results output.
i. Total Diaphragm Force
The table has been modified to show two forces for each direction, one derived from Fpx from 12.10.1.1, and the other the total force including transfer forces and any seismic forces you enter directly (as opposed to generating with building masses).
ii. Factored Force
Previously the diaphragm force Fpx shown was unfactored, but as the transfer forces are factored, it was decided to show the ASD-factored diaphragm forces.
iii. Legend
The table legend explains that
- The forces are ASD-factored
- Fpx is from Eqns. 12.10-1, -2, and -3 (not just 12.10-1)
- Transfer forces include overstrength, with the value of Ω0 and reference to Table 12.2-1
-
Total = Fpx +
transfer forces
a) Change in Standard
ASCE 7-16 has dropped an Exception 1 in 12.10.2.1, allowing the collector forces to be limited to those derived from the maximum diaphragm force, 12.10-3. However, this does not affect Shearwalls, which uses the other exception that refers to all 12.10.1.1, which includes 12.10-3.
b) Forces from Continuous Shearlines on Upper Levels*
Because 12.10.1.1 refers only to transfer forces from discontinuous shearlines, it was thought that forces from continuous shearlines above the level with the collector were not to be included in the “seismic forces originating in other parts of the structure” referred to in 12.10.2. However, in a communication, ASCE clarified that they were to be included, so now Shearwalls adds the design shearline forces (based on base shear) from shearlines on the upper levels, to the shearline force based on diaphragm design force Fpx.
Because Fpx -based forces are given as a minimum force in 12.10.1.1., the larger of the base-shear-based shearline force and the Fpx -based shearline force is used for drag strut force calculations. Previously the larger of the design shear force and the Fpx -based force without upper levels was used, making it much less likely that Fpx -based forces would govern.
c) Seismic Design Category B*
Because there is no explicit guidance on Seismic Design Category B, 12.10.2.1, which mandates use of the Fpx -based force as a minimum force for collector for SDC C-F, was applied to SDC B as well. This is no longer the case, and the base-shear based design shearline forces are used for SDC B with no minimum Fpx -based force applied.
i. Shearline Force*
In the Collector Forces table of the Design Results (previously called Drag Strut Forces), for each shearline, the shearline force used to create the drag strut force is now shown.
ii. Legend
The legend entry for Drag strut Force in the Collector Forces table of the Design Results has been modified to indicate:
- That only for SDC C-F is it the greater of the design shear force and the Fpx-based force used
- Forces from discontinuous shearlines are added in, and factored for overstrength by Ω0
- Shearline forces from story above added
- To refer to the Seismic Information Table for diaphragm force and Ω0
8. Out-of-Plane Wall and Wall Anchorage Forces (12.11.1 and 12.11.2.1)
a) Change in Standard
12.11.1 for out-of-plane wall forces and
12.11.1.1 for wall anchorages have been reorganised and rephrased to remove the
ambiguity that suggested both sections referred to anchorages. 12.1.1 now
refers to wall forces only.
The only substantive change within the
reorganization is that there is now a minimum force of 0.2 Wp to be
applied to the wall, where Wp is the weight of the wall tributary to
the diaphragm.
b) Calculation of Anchorage Force
The anchorage force is now taken as 0.2 Wp
for those cases that 0.4 SDS Ie ka < 0.2,
where ka is the flexible diaphragm amplification factor defined in
12.11.1.1.
C. Update to ASCE 7-16 – Wind Load Generation (Feature 239)
1. Ground Elevation Factor (7-16 26.9; 7-10 C27.3.2)
a) Change in Standard
A ground elevation factor Ke has been added to account for the effect of altitude on velocity pressure qz in equation 26.10-1 (Section 26.10.2). Ke is determined from Table 26.9-1 or the equation in Note 2 to that table. The equation
Ke = e-0.000119zg
with zg in meters, is based on the formula for change in pressure p or density ρ with altitude z,
p/p0 = ρ/ρ0 = e -gz/RT
g is acceleration due to gravity, R the gas constant of air, and T is temperature in Kelvin = 288 degrees.
Previously a procedure in C27.3.2 was used to modify the factor 0.0256 in the equation for qz for the change of air density with altitude. The density was taken from a table, and the factor is just ρg in the expression p = ρgv2 for velocity pressure. Now the sea level factor 0.0256 is always used and then modified by the Ke factor.
Note that the concept of minimum, average and maximum density based on factors such as temperature, weather, season and latitude has been dropped and the new formula is based on density at 15 degrees C. Note too that the densities shown in ASCE 7-16 Table C26.9-1 do not correspond exactly to any of the minimum, maximum, or average densities from 7-10 C27.3-2, so this is a substantive change to the calculation of velocity pressure in all cases other than sea level pressures.
b) Input
The data group Velocity
pressure coefficient (C27.3.2) in the Site Information dialog has
been renamed Ground elevation factor Ke.
The input of the air density category (minimum, average, maximum) and ambient air density, and the display of resulting mass density constant, have been removed. The Altitude input has been retained, and the resulting Ke factor is shown.
c) Calculations
The calculation of the mass density constant has been removed and it is now always 0.0256. The Ke factor is calculated using the equation in Note 2 of Table 26.9-1 and applied to the velocity pressure qz in equation 26.10-1.
d) Output
In the Wind Load Generation Details,
Ke has been added to the Definitions, as has ground elevation zg. The definition for what we called d, the mass density constant, has been removed.
Ke has been added to the equation for q, which has also been changed to show the number 0.0256 instead of the symbol d for air density. The equation for Ke has been added and the one for d removed.
The value calculated for Ke has been added to the Data (all loads) section.
2. Enclosure Classification (7-16 26.12; 7-10 26.10)
a) Change in Standard
A Partially Open category has been added for those buildings that are not Open, Enclosed, or Partially Enclosed. Previously Enclosed buildings were defined as not Open or Partially Enclosed, but now they are defined by having opening area in each wall less than the lesser of 4 sq. ft. or 1% of the wall area.
The internal pressure co-efficients GCpi for Partially Open walls are the same as for Enclosed, +0.18 and -0.18, so this change does not impact pressures generated.
b) Input
In the Site Dialog, Partially open has been added to the list of Enclosure choices. The wording Partly Enclosed has changed to Partially enclosed.
These changes are also reflected in the Site
Information section of the Wind Load Generation Details.
c) Enclosure Estimation
The program applies the new rules to the estimation of enclosure classification that is triggered by a button in the Site dialog. Note that a “wall” is taken by Shearwalls to mean an entire building face.
d) Load Generation
Internal pressure GCpi coefficients 0.18 and -0.18 are applied to the Partially Open walls when selected.
A limit has been added to the end zone width a for low-rise structures greater than 300 m in each dimension, with roof slopes less than 7 degrees. For these structures a is limited to 0.8 times the mean roof height h.
This limit is applied to those structures designed using the Envelope Procedure. The ordinary end zone width is defined as
a = max (min
(.1 D, 0.4h), max ( 0.4D, 3ft) ).
where D is the least horizontal dimension of the building. For
buildings whose least horizontal direction is greater than 300 ft, this is now
a = min (max
( min (.1 D, 0.4h), max ( 0.4D, 3ft) ), 0.8h).
End zones defined for the Envelope Procedure for MWFRS loads in
Fig 28.3-1 have elevated pressure coefficients relative to the rest of the
building face, and for C&C wall loads defined in Fig 30.3-1 have elevated
coefficients for negative pressures (suction).
Note that there are few wood buildings with both dimensions greater than 300 ft.
D. Force-transfer Walls (Feature 33)
Design of the force transfer walls in Shearwalls follows what is known as the Diekmann method, as presented in APA T555, Design for Force Transfer Around Openings (FTAO). The program also conforms to Special Design Provisions for Wind and Seismic (SDPWS) 4.3.4.4 and 4.3.5.2.
In the Diekmann method, shear forces are developed in each wall “pier”, defined by the rectangular areas:
- between an opening and the top or bottom of the wall (opening pier)
- between two openings or an opening and the end of the wall (central pier),
- between a central pier and the top or bottom of the wall. (corner pier)
A central pier is defined by the top of the highest opening and the bottom of the lowest one.
1. Limitations
Force transfer walls are subject to the following limitations:
a) Opening Configuration
There must be least one foot of sheathing above and below each opening, to allow shear forces to develop in opening piers. A consequence is that walls with doors cannot be designed as force transfer walls. One solution to this situation is to create a non-shearwall for the door.
b) Height-to-Width Ratio
As per SDPWS 4.3.5.2 and 4.3.4.4., each central pier (i.e. between openings or between opening and wall end) must conform to the height-to-width limitations given in Table 4.3.4, that is, 3.5:1 for blocked walls and 2:1 for unblocked walls.
c) Pier length
As per SDWPS 4.3.5.2.(1), the length of the wall piers (distance between openings or distance between an opening and the wall end), must be 2’ or greater. According to advice we received from FTAO researchers, this limitation has been applied to unblocked walls only; for blocked walls the piers must be 18” or longer.
d) Full-height End Segments
As per SDWPS 4.3.5.2.(2), a full height segment must be at each end of the wall, that is, a force-transfer wall cannot start at an opening.
e) Gypsum Materials
Gypsum wallboard or plaster sheathing materials are not compatible with force transfer walls. If such materials exist on a force transfer wall, they are ignored for both design and deflection calculations.
2. Other Considerations
Shearwalls does not consider all the force-transfer details required to ensure that the assumptions of the Diekmann method are satisfied. The designer is responsible for verifying the strength of all elements and connections in the load path using sound engineering judgement. In particular:
a) Width-to-Height Ratios
SDPWS provides only height-to-width limitations, and in ordinary shear wall segments, width-to-height is rarely an issue. However, for force-transfer walls, narrow piers above openings can have very high width-to-height ratios such that they cannot be relied upon to transfer shear forces. For example, using our 1-foot pier height limitation, a 4-foot opening exceeds the 3.5:1 width-to-height ratio.
In the absence of design code guidance, Shearwalls does not check pier width-to-height and leaves the design of openings to your judgement in this regard.
When sheathing is configured such that panels wrap around the openings in a C- or L-shape with no seam between the corner pier and the opening pier or central pier, shear is transferred through the sheathing rather than via the straps and blocking, and the assumptions of the Diekmann method are not valid. Tests have shown extremely large differences between actual forces and those computed by force-transfer analysis in this case.
Shearwalls does not consider sheathing layout details (other than whether the panels are applied vertically or horizontally). It is the responsibility of the designer to ensure seams exist on the studs at the sides of opening segments or on the force transfer blocking so that force is transferred through blocking and straps rather than sheathing.
3. Continuous Force Transfer Strap Setting
A setting called Continuous strap across entire wall has been added to the Design Settings. If checked, it is assumed that the force transfer straps and blocking extend in one straight line across the entire wall, so that all central piers extend from the top of the highest opening on the entire wall to the bottom of the lowest opening on the wall. The opening piers and corner piers are also measured from the top of the highest opening and bottom of the lowest opening, so that some sheathing may be contained within the opening area that does not resist shear force.
If unchecked, it is assumed that strapping and blocking exist at the top and bottom of each opening and extend far enough into the adjacent segments to transfer shear force to the central piers. In this case, the central piers extend from the top of the highest of the two adjacent openings, to the bottom of the lowest of the adjacent openings. The opening piers are measured from the top and bottom of each opening.
The use of non-continuous straps does not provide an advantage in terms of shear forces developed as the force developed in the core of the central pier is the same in either case. Strap/blocking forces may be lower; but more strapping and blocking are required due to overlap. The use of this option is recommended only to avoid large strap forces, or if it is more convenient to construct the wall with blocking at the top and bottom of openings.
4. Input
a) Wall Input View
A wall type called Force-transfer has been added to the list of wall Types in wall input. Walls of this type that have openings are displayed with square hatching, to distinguish them from perforated walls (diagonal hatching) and segmented walls (solid). A legend item has been added to show the force transfer hatching.
Force transfer walls without openings appear in solid colour.
b) Limitations
The limitations on force-transfer wall geometry are imposed when you change the wall’s geometry in any way, i.e. via lengthening, shortening, changing the height, adding or removing openings, or changing opening dimensions. If this causes segments that are too narrow, piers with disallowed height-to-width ratios, or openings that are too close to the top or bottom of the wall, a warning is issued and the wall configuration is reverted to what it was before the change.
If an existing segmented or perforated wall, or non-shearwall, is changed to a force-transfer wall, the program checks the limitations and if any one is violated, a message is issued, and the change is reverted.
c) Standard Wall
A standard wall called Exterior Force-transfer has been added to the list of standard walls that appear when you first run Shearwalls or select Reset original standard walls from the Default settings.
d) Walls with No Openings
Walls designated as Force-transfer walls but have not yet had an opening placed in the wall, are in every respect treated by the program as segmented walls.
Shear force distribution to the piers in force-transfer walls is described in APA T555 as a sequence of numerical calculations in a design example of a wall with 2 openings of the same size. The following gives an algebraic formulation of the general procedure used by Shearwalls; it corresponds to the calculations in the T555 example.
a) Symbols
The following symbols are used in the shear force distribution equations:
V – Total shear force on wall (lbs)
– Unit
shear force in piers above and below openings
– Unit shear force in central piers
– Unit
shear force in corner piers above central piers
–
Height above openings
–
Height above openings
–
Height of wall
– Length of wall
–
Length of opening
– Length of opening to the right of pier under
consideration
–
Length of opening to the left of pier under consideration
– Length of central pier under consideration
–
Length of central pier to the left of the central pier under consideration
–
Length of central pier to the right of the central pier under consideration
– Strap force on the left side of an opening
– Strap force on the right side of an opening
b) Piers above and Below Openings
The total shear force in a vertical line on the wall is equal to the hold-down force VH / L (neglecting hold-down offsets), so the unit shear force in the upper and lower piers is that force divided by the length of the combined height of the piers:
The force in the central piers is:
This is the unit diaphragm shear force over the segment with the central pier plus the portion of diaphragm shear force over the openings on either side of the pier transferred to the pier via straps and blocking. This portion is determined by multiplying the unit diaphragm force by the ratio of the adjacent opening lengths to the combined length of the central piers on either side of these openings.
d) Corner Piers
The unit force in the corner pier is the unit force in the central pier minus the strap/blocking forces from each side divided by the length of the pier.
The strap/blocking forces are the total force (not a unit force) above and below the opening apportioned to the left and right side by the proportion of total length of the piers on each side.
‘
Walls designated as force-transfer without openings are treated as segmented walls.
6. Design
a) Aspect Ratio Factor
Although it isn’t explicitly stated in SDPWS 4.3.4.4, we were informed that the intention of the SDPWS is that force-transfer wall central piers that have height-to-width ratios between 2.0 and 3.5 are subject to the Aspect Ratio Factor given in 4.3.4.2 (for deflection-based distribution to segments), and the adjustments in the Exceptions to 4.3.3.4.1 ( for capacity-based distribution).
These are the same factors and adjustments used for segmented wall full-height segments, except that for force-transfer walls they applied to the dimensions of the central piers between two openings or between an opening and the wall end.
b) Critical Design Shear Force
The program determines the critical case of pier force / Aspect Ratio Factor for any pier in the wall (including corner and opening piers with a factor of 1.0) and designs the wall for that case.
c) Gypsum Materials
The contribution of gypsum wallboard and plaster materials is ignored in calculating design strength of force-transfer walls, regardless of what is set in the Ignore contribution of... Design setting.
7. Hold-downs and Hold-down Forces
Force-transfer walls require hold-down devices only at wall ends, so that hold-down forces in Shearwalls are at the ends of force-transfer walls and there is no hold-down at the sides of each opening.
a) Input and Output
Hold-down devices are input only at the ends of entire walls, as for perforated walls. Hold-down forces are reported in Plan View, Elevation View, and the Hold-down Design table only at the end of walls.
b) Force Calculation
The shear force used for overturning calculations is the shear force applied to the entire wall. Dead and wind uplift loads over the entire length of the wall are distributed to the hold-downs at the end of the wall, so the hold-down force calculations include the dead and wind uplift loads over openings, instead of distributing them to opening supports.
c) Axial Wall Stud Forces
The unit shear forces in the piers that are shown acting horizontally also act vertically along the studs at wall and opening ends. The vertical forces at the wall end add up to the hold-down force, neglecting the hold-down offset.
Beside the openings, tension and compression axial forces are developed in the studs due to the difference in shear force in piers adjacent to the studs. Shearwalls does not calculate or report these forces, but they should be considered when designing the wall.
8. Deflection
The procedure for calculating deflection of force transfer walls comes from APA T555, Design for Force Transfer Around Openings (FTAO). This applies only to force transfer walls with openings; those without are treated as segmented walls.
a) Reduced Segment Height
In this method, the deflection due to the shear force in the central pier is calculated on each wall segment between openings, but assuming that the height of all but one of the segments is the height of the central pier plus the top pier only, i.e., the bottom pier is ignored. The one segment that is still considered to be full height is at the far end of the wall from the force direction.
b) Averaging of Segment Deflections
This analysis is done in both force directions using the same wall shear force, then all the deflections from the segments in each direction are averaged to arrive at the deflection of the entire wall; i.e. if there are n segments, 2n segment deflections are averaged.
That is, if E->W wind loads are different than W->E loads, due to for example a monoslope roof, then for the E->W force direction, the E->W force is used for both E->W and W->E directions, then all the deflections are averaged. The same thing is done again for the W->E force direction using W->E loads.
c) Force Distribution
The forces used to calculate the deflection of each segment for the purpose of deflection design are as follows:
i. Force Distribution to Segments within Walls
The unit shear force v used for deflection calculations is the central pier shear force determined through force-transfer shear force distribution to piers (see 5 above). Therefore, the deflections of the segments within the shear wall that are later averaged are not equalized, even if deflection-based shear distribution to segments is selected in the Design Settings.
ii. Force Distribution to Sheathing on Each Side
The distribution of the force to sheathing on either side of a segment in a two-sided shear wall is determined by equalizing the nail slip plus shear components of the deflection equation.
iii. Force Distribution to Shear Wall in a Shear Line
If deflection-based shear distribution to segments is selected in the Design Settings, the force on the force-transfer shear wall in a shearline is determined by equalizing the deflection of the entire wall with other force-transfer or perforated walls, and with all the segmented wall segments on the line. In other words, the segment-averaging process for a force-transfer wall is incorporated into the iterations that equalize shear wall deflections on the entire line.
d) Shear, Bending and Nail Slip Components
The calculation of the shear, bending and nail slip components in the equations for deflection from SDPWS C4.3.2 use the reduced segment height h. The shear and nail slip terms are linear in h; the bending term is proportional to h3.
e) Hold-down Displacement Component
The hold-down displacement contribution to deflection at each interior segment of the force-transfer wall is calculated as if there was a hold-down device at each opening, even though they are not present in force-transfer walls. The wall anchorage term in the equations for deflection in SDPWS C4.3.2 is calculated as follows:
i. Shear Overturning Force
The shear overturning force is calculated using the reduced moment arm of those segments that are considered to extend from the bottom of the opening to the top of the wall. For full-height end segments, the wall height is used as the moment arm.
ii. Dead and Wind Uplift Force
Dead loads and wind uplift loads on the same level as the segment are distributed to the segment ends for the purpose of deflection calculations. Dead and wind uplift loads over openings are distributed to the fictitious hold-downs at the sides of the openings, as if it was a segmented wall.
iii. Forces from Upper Levels
Dead, wind uplift and overturning hold-down forces from floors above are included in the calculation of hold-down deflection if the hold-down forces on the wall above and on the wall below are at the same location. ; that is, these segments behave as segmented walls do in this regard.
iv. Height-to-Width Factor
The factor h/b in the wall anchorage term uses the reduced segment height h for those segments considered to extend from the bottom of the opening to the top of the wall. For full-height end segments, the wall height is used.
v. Hold-down Devices Used
For deflection calculations, the virtual hold-down devices used for the left end of all openings are those selected for the left end of the wall, and those used at the right end of openings are those used at the right end of the wall.
When calculating deflections in the opposite direction, the hold-downs are flipped, so that for one actual force direction, the same hold-down devices are subjected to tension in all the deflections that are averaged to give the resulting wall deflection.
f) Gypsum Materials
The contribution of gypsum wallboard and plaster materials is ignored in calculating deflections of force-transfer walls, regardless of what is set in the Ignore contribution of.. Design setting.
9. Drag Strut Forces
Collectors are required throughout the full length of the force-transfer wall according to SDPWS 4.3.5.2(4). We received confirmation that this clause refers to the transfer of forces from the diaphragm to the shear wall, not the internal transfer of forces around openings via blocking and straps. A continuous collector is necessary because the shear force distribution to force-transfer piers creates differential forces in the top piers of the wall, so that axial tension and compression forces build up in the top plate of the wall, which acts as a collector dragging or pushing the uniform shear force from the diaphragm above to the piers below.
Shearwalls reports these drag strut forces at the sides of each opening and at the ends of the wall where there is a gap in the shear line. These locations are where the local maxima and minima of tension and compression forces occur, and these forces vary linearly between these points.
a) Comparison with Segmented Walls
These are the same locations drag strut forces appear for segmented walls, but the mechanics for force transfer are quite different.
For a segmented wall, there is no shear resistance in the sheathing above openings, so that the drag strut above the first segment with an opening drags additional force into the segment to the left, and pushes additional force into the segment at the right, typically creating tension in the drag strut at the left side and compression at the right.
For a force-transfer wall, the shear force in the sheathing above the opening is typically greater than the corner pier forces, so that the drag strut pushes additional force into the pier above the first opening from the left, and pulls it into this pier from the right. This typically creates compression in the drag strut at the left side and tension at the right.
10. Elevation View
The following changes have been made to Elevation View output for force-transfer walls:
a) Piers
The boundaries of force transfer piers are shown as light blue lines.
b) Pier Forces
Shear forces in each pier are shown at the bottom of each pier in the same way that the design shear force is shown at the bottom of the wall for segmented walls. For offset openings and the non-continuous strap setting, the pier force is shown at the bottom of the pier (lowest opening) for consistency, although the full shear force is developed at the bottom of the higher opening.
c) Segment Shear Forces
The program shows only one large arrow at the top of the wall for the total force on the wall, not forces on each segment as it does for segmented walls.
d) Straps and Strap/Blocking Forces
Straps are shown as two thick, closely spaced lines above and below the openings and extending into neighbouring segments. For continuous straps they extend the full length of the wall at the height of the highest opening top and lowest opening bottom. For non continuous straps, the extend the length of the full height segment adjacent to the opening.
The strap/blocking forces are shown at each corner of the opening. The program does not indicate the direction of the force or whether it is in tension or compression; typically for left-to-right shearline forces, the top left strap is tension, top right blocking in compression, bottom left blocking in compression, and bottom right strap in tension.
A legend entry indicates these are strap/blocking forces.
e) Aspect Ratios
Aspect ratios and factors are shown for central piers only, in the center of the pier.
f) Dimension Lines
The vertical dimensions of piers are shown as follows:
Piers above and below openings are dimensioned in the same horizontal location as the opening dimension line.
Central piers are dimensioned if they are a different height than adjacent openings.
Corner piers are not dimensioned as they have the same dimension as an adjacent opening pier.
For continuous strap across the entire wall, only one set of piers is dimensioned; as piers in all segments have the same dimensions.
g) Shading
The program does not shade the areas above and below openings as it does for perforated and segmented walls, as these areas contribute to shear resistance for force-transfer walls.
h) Show Menu and Display Options
Items have been added to the Show menu and Options | Display settings to allow you to turn on and off the display of piers, straps and pier dimensions.
11. Output
The following changes have been made to the Design Results output to accommodate force-transfer walls. These changes apply only to force-transfer walls with openings; walls designated as force-transfer without openings are treated as segmented walls.
a) Shearline, Wall and Opening Dimensions Table
In the Shearline, Wall and Opening Dimensions table:
i. Wall Type
A type FT has been added for force transfer walls.
ii. Aspect Ratio
The aspect ratio for force-transfer walls is the aspect ratio of the central pier; this is explained in the Legend.
b) Shear Results Table
i. Shear force v Column
The force v in the column headed by v is the force in the central pier.
ii. vmax/vft Column
The column headed by vmax is now vmax/vft and shows the shear force above and below openings and in corner piers. A legend item explains this, and that the aspect ratio factor does not apply to these forces
iii. Opening Row
A line for openings now appears between each segment giving the unit shear force, total shear force, and design ratio of the piers above and below openings (which always have the same unit shear force).
iv. Aspect Ratio
The legend entry for aspect ratio factor now refers to force transfer piers
c) Deflection Table
i. Line for Entire Wall
For other types of walls, this table shows lines for wall segments only. For force-transfer walls, a line for the entire wall has been added to show the averaged deflection of all the segments in both directions.
The shear force shown in this line is the total force on wall divided by wall length. The wall dimensions and wall group are also shown, but all other columns are not used and show a hyphen (-).
ii. v Column
The column for segment shear force v shows the force in the central pier.
iii. End Segment Deflections
For end segments, the wall height h and the shear, bending, nail slip, and hold-down components of the deflection equation are the average of those derived from the full wall height and the distance from the bottom of the lowest adjacent opening to the top of wall. This is because the end segments are full height in one direction but not in the other.
The averaging of the bending term, which is non-linear in h, has been determined mathematically and does not correspond to the calculation of that term using the h shown.
iv. Interior Segment Deflections
For interior segments, the wall height is the distance from the bottom of the lowest adjacent opening to the top of wall, and all deflection components are determined using that height.
v. Legend
The legend has been modified to explain the wall width b, wall height h, shear force v, hold-down devices used, and total deflection for the entire wall and for each segment, referring to APA T555.
d) Hold-down Displacement Table
i. End Segment Height
The value used for the wall height h to determine total displacement shown for end segments is the average of the full wall height and the distance from the opening bottom to the top of the wall. This is explained in the Legend.
ii. Hold-down Device
The hold-down device shown is the one used to calculate the displacement at the segment, even though a hold-down device does not exist at that location.
e) Collector Forces Table
The Drag Strut Forces table has been renamed Collector Forces, and two columns have been added to show the force-transfer strap/blocking forces at the sides of each opening (the same locations that drag strut forces are currently shown), in each force direction.
A legend item has been added for strap/blocking forces.
- whether the Equivalent Lateral Force (ELF) procedure used by Shearwalls is allowable for each Seismic Design Category, as per 12.3.3.1
- the new regularity criterion for limiting the value of the design seismic response parameter SDS (see).
- the conditions in 12.3.4.2 whereby the redundancy factor ρ is equal to 1.0
- the application of the 25% increase in drag strut forces as per 12.3.3.4.
1. Input
In the Site Information dialog:
a) Irregularity Groups
Checkboxes have been added for both the N-S and E-W force directions for the following single irregularities or groups of irregularities, which are checked if any one of them is deemed to exist:
i. Horizontal Irregularities
1a Torsional
1b Extreme Torsional
2 Corner, 3 Diaphragm or 4 Offset
These correspond to the ASCE irregularities as follows:
- Corner = Reentrant Corner
-
Diaphragm =
Diaphragm Discontinuity,
- Offset = Out-of-Plane Offset.
If 1a Torsional is checked, then 1b Extreme Torsional is unchecked and vice-versa.
ii. Vertical Irregularities
1a Soft story, 2 Weight or 3 Geometric
1b Extreme Soft or 5a Weak Story
4 In-plane Discontinuity
5b Extreme Weak Story
These correspond to the ASCE irregularities as follows:
-
Soft story = Stiffness – Soft Story
-
Weight = Weight (mass)
-
Geometric = Vertical Geometric
-
Extreme Soft = Stiffness – Extreme Soft
Story
- Weak Story = Discontinuity in Lateral Strength – Weak Story
-
In-plane Discontinuity = In-plane Discontinuity
in Vertical Lateral Force Resisting Element
-
Extreme Weak Story = Discontinuity in Lateral
Strength – Extreme Weak Story
b) Files from Older Versions
Previously the choices were
Horizontal irregularity or in-plane vertical irregularity
Other vertical irregularity.
When opening
project files from previous versions, if the first of these was checked, then 2 Corner, 3 Diaphragm or 4 Offset is
checked for both directions. If the second was checked then 1a Soft story, 2 Weight or 3 Geometric is checked for both directions.
c) Output
The irregularities and directions selected are listed in the Site Information section of the Seismic Load Generation Details
d) Use Detected Torsional Irregularity for Design
A checkbox has been added called Use detected torsional irregularity for design. This means that if the program detects a torsional irregularity during the analysis of the structure for design, but one was not selected in the Site Dialog, it applies that irregularity to the determination of whether ELF is allowable, redundancy factor ρ, and the 25% drag strut force increase. Conversely, if no torsional irregularity is detected but one was selected in the Site Dialog, the torsional irregularity is not applied.
2. Verification of the Equivalent Lateral Force Procedure
For Seismic Design Categories D, E or F with vertical irregularity 5b, and SDC E or F with horizontal irregularity 1b or vertical irregularities 1b or 5a, the program warns you that the Equivalent Lateral Procedure (ELF) is not permitted by ASCE 7 12.3.3.1. If only the horizontal Torsional irregularity 1b exists, this applies only if rigid diaphragm design is selected.
The warnings appear if vertical irregularities 1b, 5a, or 5b are selected in the Site Information dialog, or if the following conditions are satisfied
- Rigid diaphragm design is selected in the Structure Input view, and
-
Use detected torsional irregularity is
not selected and Torsional Irregularity 1b is selected, or
- Use detected torsional irregularity is selected and Torsional Irregularity 1b is detected by the program.
a) Site Information Dialog
If a combination of inputs leading to Seismic Design Category, and Irregularity inputs, in the Site Information dialog correspond to prohibited ELF, a message appears saying seismic design is prohibited by 12.3.3.1.
b) Screen Messages
When Load generation is invoked, if ELF is prohibited, warning messages appear on the screen informing you of the reason. Note that at this point, the Torsional irregularity has not been checked by the design routine, so only the input irregularities in the Site Information dialog are used.
When shear wall design is invoked, similar warning messages appear, this time informed by the possible detection of the extreme Torsional irregularity.
c) Design Results Output
If ELF is prohibited, notes appear below the Seismic Information table and the appropriate Shear Results tables informing you of the reason and saying the results are for information only and should not be used to design the structure. A message appears in the Design Summary referring you to the Seismic Information table. The notes under the Shear results tables are displayed in red.
3. Redundancy Factor, ρ
a) ASCE 7 Requirements
For Seismic Design Categories D, E and F, structures with an extreme torsional irregularity (horizontal 1b), must have a ρ = 1.3 (in the case of E and F, the program will also warn that the Equivalent Lateral Force procedure is not allowed, see2 above). Otherwise, for these categories, satisfying one of two conditions allow ρ to be 1.0 rather than 1.3:
Condition a – Involves removing elements and checking for story strength and existence of extreme torsional irregularity 1b with the elements removed.
Condition b – The structure is regular in plan (no horizontal irregularities), and a check is made for sufficient perimeter framing.
b) Existing Implementation
Version 11 of Shearwalls detected the extreme torsional irregularity 1b to automatically assign ρ = 1.3 to structures in SDC D, E, and F, and to perform the checks for condition a with the elements removed. For condition b, it incorrectly used the Other vertical irregularity input to check for regularity of the structure.
c) New Implementation
i. Extreme Torsional Irregularity
For rigid diaphragm design, the program assigns ρ = 1.3 for SDC D-F if
-
Use
detected torsional irregularity is not selected in the Site Information
dialog and Torsional Irregularity 1b is selected, or
- Use detected torsional irregularity is selected and Torsional Irregularity 1b is detected by the program.
ii. Condition a
The program detects the possible extreme torsional irregularity when elements are removed; the input in the Site Information dialog is not used to determine this irregularity.
iii. Condition b
The plan irregularity check is made by checking for torsional irregularities 1a or 1b in the same manner described in Extreme Torsional Irregularity (i above). The structure is also deemed irregular if any other horizontal irregularity is checked in the Site information dialog.
4. 25% Drag Strut Increase
a) ASCE 7 Requirements
According to 12.3.3.4, for Seismic Design Categories D-F, the collector (drag strut) forces based on the diaphragm design force Fpx from 12.10.1.1, is increased by 25% if the structure has any horizontal irregularity relevant to Shearwalls, or if it has vertical regularity 4, In Plane Discontinuity.
b) Existing Implementation
In Version 11, the increase was applied for SDC D-F to all drag struts in the building if you selected Horizontal Irregularity or In-Plane vertical irregularity in the Site information dialog
c) New Implementation
For Seismic Design Categories D-F
i. Torsional Irregularity
For rigid diaphragm design, the 25% increase is applied if
-
To all
drag struts in the building if Use
detected torsional irregularity is not selected in the Site Information
dialog and Torsional Irregularity 1a or 1b is selected, or
- Use detected torsional irregularity is selected and Torsional Irregularity 1a or 1b is detected by the program on the level with the drag strut.
ii. Input Irregularities
The 25% increase is applied to all drag struts in the building if any of the other horizontal irregularities (than torsional irregularities) are selected in the Site Information dialog, or if Vertical Irregularity 4 – In plane discontinuity is selected.
iii. Horizontal Irregularity 4 – Out-of-Plane Offset
The 25% increase is applied if on the level above the drag strut, anywhere on the level above the shearline with the drag strut, there is a shearline in that direction with no line on the level below. This is regardless if this irregularity is checked in the Site Information dialog.
iv. Output
In the Collector Forces table (formerly Drag strut forces), a line has been added to the legend to explain the conditions under which the 25% increase is applied.
5. Limit on Value of SDS
Refer to A.4.d)iii above, under Maximum SDS Value in the Determination of Cs and Ev (12.8.1.3), for the application of the new regularity criterion to this provision.
6. Perforated Wall Note (Change 105d)
A note has been removed from the Hold-down Design table regarding Irregularities not being checked.
F. Load Generation and Force Distribution
Refer
also to the changes listed in the section with the same name under Version
11.2,
1. Low-rise Wind Loads for Multiple Blocks and Asymmetric Structures (Feature 245)
The method of determining external pressure coefficients CpCg for low-rise structures from ASCE 7 Figure 28.3-1 assumes symmetric, rectangular structures. They are based on boundary layer wind tunnel studies of buildings of that shape, verified against full scale measurements. As relatively few low-rise structures have such a regular shape, Shearwalls now extends this method to buildings with multiple blocks and/or eccentric ridge lines.
a) Intersecting Blocks
When two blocks intersect such that the slope of a
portion of a roof can be formed either by either the side panel of one block or
the end panel of the other, such as one
roof framing into another to form an L-shape, the manner in which the building
is modelled does not affect the wind loads generated when the load generation
option of treating end hip panels as side panels is chosen. However, if the
ASCE 7 C28.3-2 is used, then it does make a difference. It is recommended to
use the side panel option with wind load generation. If the C28.3-2 method is
used, it is best to join blocks such that composite roof surfaces formed by the
hip end of one block and the side panel of another are avoided.
i. Walls
The area of exterior walls beneath a sloped roof are considered to “have” the slope of the roof for the purpose of Case A (transverse) load generation, which depends on roof angle. If there is a hip end in the Case B (longitudinal) direction, and side panel Case A coefficients are used on the wall beneath the hip end, they are the same as the rest of the building face formed by the side panel of the other block.
ii. Roofs
A hip end panel in the same plane as a side panel on another block has the co-efficient from the same load case as the side panel, so it is equivalent to the situation where the side panel from one block forms the roof on the entire face and the other block joins that block without forming a hip end.
b) Differing End Panels
Previously the program disallowed structures for
which the hip ends on opposing ends of a block had different slopes, or there
was a hip on one end and a gable on the other. Now these structures are
allowed, and the coefficients used on the roof panels and the walls below the
panels are based on the angle of each roof panel.
c) Eccentric Ridge Lines
Previously the program disallowed the case of an
eccentric ridge line with different slopes on either side of the ridge. Now
this case is allowed, and the coefficients used on the side roof panels and the
walls below the panels are based on the angle of each roof panel. This applies
to each roof on a structure with multiple blocks.
d) End zones
End zones are created wherever the corner of a
block is an exterior corner of the structure. End zones are not created where
two blocks join each other forming either a straight wall and roof, or an
interior corner.
e) Basis for Height-to-Width Limit Design Setting
The data group Apply height to-width ratio to…has been
changed to Low-rise height-to-width limit
based on… and provides
choices for Single block and Entire structure. The definition of
low-rise structures in ASCE 7 26.2 says they must have mean roof height less
than least-horizontal dimension, and in the absence of guidance in the ASCE 7,
this setting is used to specify whether this limit is to be applied to each block
or to the structure as a whole.
Note that the Apply height to-width ratio to… setting
had no effect in previous versions of the program, as they did not allow
multi-block low-rise structures.
f) Screen Warnings
The error messages that appeared after Generate Loads was invoked saying that
load generation was not possible due to unequal hips, eccentric ridge lines, or
multiple blocks, have been modified to provide warnings and suggestions for
these reasons, but to indicate load generation will proceed.
g) Load Generation Details
In the Load
Generation Details output:
i. Header Note
A note in the header section of the Wind Load Generation Details output indicates that the building does not conform to strictly to Figure 28.3-1 for the following reasons, which are only included if applicable to the structure: multiple blocks, eccentric ridge lines, or unequal hip or gable ends.
ii. Load Table
There are now load tables for each block for multiple block structures, where previously only one table was possible.
h) Torsional Analysis Details
If there are multiple blocks of which any two have
orthogonal ridge lines, then both Case A and Case B loads can exist in the same
wind direction on different blocks. In
this case, in the Torsional Analysis
Details output where it otherwise says Low-rise
Case A or Low-rise Case B, it
says Low-rise Case: and then Wind Generally North-South or Wind Generally East-West.
For orthogonal ridge lines, where the section for
Case A previously had results for only one load direction, there are now
results for both directions.
i) Show Menu Options
Since Case
A and Case B loads
can exist in the same wind direction on different blocks, for multi-block
structures, in the Show menu and associated Options settings under Display,
- Wind Load Case is changed to Wind Direction
- the Case A Side, Case B End show menu option is disabled
- the words (Case A) and (Case B) are removed from the North-South and East-West options
Previously, Shearwalls analyzed low-rise wind loads from ASCE 7 Figure 28.3-1 by considering pressures in the E-W and N-S directions independently and did not consider the combined effect of these pressures on torsional analysis for rigid diaphragm force distribution to shearlines.
Shearwalls now includes loads due to pressures from both directions in the torsional analysis routine simultaneously, so that torsional forces from E-W loads are considered when determining N-S forces, and vice-versa.
Note that it is only Case B that has simultaneous pressures in both directions.
a) Load Cases Considered
This has been implemented for the Basic Load Case only and will capture torsional effects due to structural asymmetry and end zone effects. The Torsional Load Cases in Figure 28.3-1 which specify partial loading have not been implemented in Shearwalls.
b) Calculations
In the torsional analysis routine, the program now calculates the torsion T in the equation
Fti = T Ki li / (Jx + Jy)
as Tx + Ty
for both directions, when previously Tx
was used for one direction and Ty
for the other. Refer to the
Torsional Analysis Details output for the definitions of these variables.
c) Torsional Analysis Details Output
In the Torsional Analysis Details file (previously the Log file) , for load Case B
- A note has been added to the top saying explaining the simultaneous design, referring to Note 3 in Figure 28.3-1.
- The Concentrated Load F, Center of load Cl and Eccentricity etx values are shown in a table at the top for both directions, rather than separately for each direction. F and Cl now show subscripts for direction, e.g. Fx and Cly
- The equation of torsions has been modified to show both directions rather than one.
3. Equalizing Deflections on Both Sides of a Shear Wall
The following improvements were made to the equalizing of deflections of the sheathing on either side of a shear wall, as a step in the process of equalizing deflections along the shearline as required by SDPWS 4.3.3.4.1. This affects force distribution to segments within a shearline when using the deflection-based distribution Design setting. Equalizing deflections on both sides of the wall for the 4-term equation C4.3.2-1 entails equalizing the sum of shear and nail slip terms in the equation, as the bending and hold-down terms affect both sides equally. For the linear 3-term equation from SDPWS 4.3-1, only the shear term is equalized.
a) Numerical Procedure for 4-term Equation (Change 45b)
For the non-linear 4-term the program now implements the Newton-Raphson numerical procedure rather than a more time consuming “brute force” procedure. The Newton-Raphson method always converges to a solution when there is one, in less than 10 iterations as opposed to 100 or more for the brute force method and converges more reliably.
The Newton-Raphson method is used to solve the non-linear equation
δi(vi)
= δe(ve),
where δ is the sum of deflections from the linear
shear term and non-linear nail slip term. Subscripts i and e refer to the interior and exterior sides of the segment.
This can be reformulated as a one-dimensional problem as follows,
D(ve) = δe(ve)-
δi(v-ve) = 0,
where v is the known
force on the segment.
The Newton method follows the slope (derivative) of D(ve) down to the ve axis.
The derivative is
dD/d(ve) = d(δe(ve)-δi(v-ve))/ dve.
It is convenient to calculate the derivatives with respect to both vi and ve , and noting vi = v - ve
dD/d(ve) = dD/d(vi) = dδe(ve)/d(ve) + dδ(vi)/d(vi),
where
dδ(ve)/d(ve) = h/gvtv + 0.75hβ(s/12γ)β
veβ-1, and similarly for vi,
where s is nail spacing in inches and γ and β are parameters from SDPWS Table C4.2.2D.
b) Algebraic Procedure for 3-term Equation (Change 45c)
When using the Design setting that linearizes the non-linear 4-term equation into a linear 3-term equation, the program was unnecessarily using the same slow iterative approach as was used for the non-linear 4-term equation. It now solves this equation algebraically. Defining α = h / 1000 Ga as the shear term factor of v in the linear 3-term equation and α i and α e represent α value on the interior and exterior,
ve = v αi
/ (αi
+ αe)
vi = v - ve
c) Assignment of No Force to One Side of Wall (Change 45a)
Occasionally, all forces were placed on one side of the
wall when there should have been some force on both sides. This was a problem
with the “brute force” iterative procedure and has been corrected in the course
of implementing numerical methods.
4. Sign Convention for Torsional Analysis
In the Torsional Analysis Details file, distances such as center of load, center of mass, shearline location and eccentricity have been based on a fixed co-ordinate system with its origin in the southwest corner of the structure. S->N distances are positive, and N->S are negative.
The forces F, however, are based on the direction of applied force; for N->S applied force, all values in the N->S direction are positive; for S->N applied force, they are negative.
Some users find this confusing and wish to see all values relative to the same fixed co-ordinate system. Other users, however, wish to see positive shearline forces when they are in the direction of the applied force, and this corresponds to the way they are presented in the Plan view drawing.
Accordingly, we now offer a choice in the Options settings of showing forces based on a fixed co-ordinate system, or relative to the applied force.
5. Display of Seismic Diaphragm Design Loads and Forces (Feature 252)
The program now displays the loads to be used for diaphragm design derived from Fpx defined in ASCE 7 Equations 12.10-1,2, and 3, and the shearline forces derived from these loads that are used for drag strut design as per 12.10.2.1.
Note that as per 12.10.1.1, diaphragm design forces are minimum forces, and if the effects of the loads derived from structural analysis in Section 12.8 are greater, these should be applied.
a) Control of Display
Items have been added to the Show Menu under Loads saying Diaphragm Design Loads and under Forces saying For Drag Strut Design, which are enabled when viewing the Seismic load case in the Loads and Forces view only, i.e. not when in Generate Loads view.
b) Diaphragm Design Loads
The loads shown are those derived from Fpx, including transfer forces from the floor above, distributed in proportion to the building masses on that level, i.e. they have the same load profile as the loads for shear wall design derived from Vx from Eqn. 12.8-13, but a different magnitude.
i. Transfer Forces
Transfer forces from discontinuous shearlines on the level are shown in Shearwalls as point loads on the level below. When diaphragm loads are shown, this load is factored by the overstrength factor Ω0.
as per 12.10.1.1.
ii. Critical Loads
These loads are always shown when Diaphragm Design Loads is selected, even though they may not be the critical ones for design of every diaphragm element. In some cases, the Fpx-based loads are of a lesser magnitude than the Vx-based loads, but the increased transfer force from a discontinuous shearline makes these loads critical for some part of the diaphragm. For this reason, it is left to the judgment of the designer as to which set of loads to use to design an element.
c) Shearline Forces
The shearline forces shown are those used for drag strut design, that is, the largest of the forces derived from Fpx-based loads and Vx -based loads.
For Seismic Design Category A and B, only the Vx-based forces are shown, as ASCE 12.10.2.1 applies only to Categories C-F.
d) Seismic Load Generation Details
For the following items, definitions of have been added to the Legend to the Seismic Load Generation Details and equations added to the Equations section.
-
Diaphragm design force Fpx,
- Fpx-based building mass element force Fpe
- Fpx -based shearline force Vpjx,
- Discontinuous shearline force Vdjx
- Collector shearline force on shearline force Vcjx
6. Display of Discontinuous Shearline Forces in Plan View
Forces from discontinuous shearlines from the floor above are shown in Plan View on the level below as a point load. However, there is also a point load in the same place from the building mass from the lower half of the wall on the level above. These two forces obscured each other. Now, the transfer force from the level above has been repositioned such that both forces are visible.
7. Redundancy Condition b for Seismic Design Category D to F
Regarding the condition “b” of ASCE 7 12.3.4.2 under which structures in Seismic Design Category are permitted to have a redundancy factor ρ = 1.0:
a) Number of Bays
In determining whether the determined whether the required seismic force resisting “bays” existed, the program was not restricting the calculation to those stories that had more than 35% of the seismic base shear. Note that according to ASCE 7 12.3.4.2, virtually all stories of 5-6 story structures have 35% of the base shear, so this problem was unlikely to arise.
b) Force Directions
A literal reading of ASCE 7 12.3.4 would suggest that the factor ρ = 1.3 be applied in both directions if conditions (N-S and E-W), a and b were not satisfied in just one of them, and that is the way Shearwalls was operating. However, we applied were not being calculated separately in each direction (N-S and E-W), and if it was not satisfied in either it would result in ρ = 1.3 in both; now it is evaluated for each direction separately.
8. Seismic Show Menu Options (Change 252)
a) Wind Load Cases
When seismic loads are selected, the Wind Load Case options are now disabled. Previously the selections were available but had no effect.
b) Force / SFRS Direction
The Force Direction item has been renamed SFRS Direction, for consistency with the change to MWFRS for wind. SFRS stands for Seismic Force Resistance System
c) Load / Force Direction
The Load Direction input has been renamed Force Direction, as the shearline and hold-down forces are the only things that could potentially change when an opposing direction is selected.
9. Output of Shear Factor Cvx for Seismic Design Category A (Bug 3200)
For Seismic Design Category A, in the Distribution of Base Shear table of the Seismic Load Details file, nonsensical values were shown for the vertical distribution factor Cvx from ASCE 7 Eqn. 12.8 -12. This is because Cvx is not applicable to SDC A as per ASCE 7 11.7 and 1.4.
The column for the Cvx factor now shows a “-“ in this case, as does the hx * wx column, which is not relevant to SDC A either.
Refer
also to the changes listed under Version 11.2,
The program user interface has been changed to have a more up-to-date look and feel. Consequently:
a) Asterisk and Note for Editable Drop-down Boxes
Editable drop-down boxes now have a different appearance than for those you can only select a value, so the asterisks appearing before these boxes and the corresponding notes at the bottom of Beam and Column View have been removed.
b) File Save and File Open Boxes
For Sizer 11, the program reverted to an old-fashioned style of standard Windows File Open and File Save as dialog boxes that had not been in use since Sizer 9.x. The more modern boxes that were used in Sizer 10 have been restored.
2. Menu Item for Auto-saved Files (Change 39a)
A new menu item Open Autosaved File menu has been added under File menu to provide direct access to auto-saved backup files BackupPre.wsw and BackupPost.wsw. Refer to the On-line Help for the use of these files. Explanatory status bar messages are displayed if you hover over the menu items.
3. Menu Item for Change History
An item Features and Changes has been added to the Help menu, which accesses this Change History document.
4. Drag Strut Display and Output (Feature 177)
The following changes have been made to the display of drag strut forces in Elevation View
a) Location of Symbol and Force
The symbol with a circle and arrow showing the drag strut force has been moved up to be just below the top of the wall. Previously the forces were shown at the top of openings. The drag strut forces are typically in the top plate of the wall, not the opening headers, and this change avoids conflict with the new force-transfer strap forces.
b) Direction of Arrow
The direction of the force arrow now indicates whether the drag strut is in tension or compression at that point. Previously the arrows always pointed away from the opening or wall end.
An arrow in the direction of the shearline force is in tension, one contrary to the shearline force is in compression. An arrow in the same direction as the shearline force pointing into an opening segment is dragging the force over the opening into the full height segment. An arrow in the opposite direction pointing into an opening segment shows the full height segment resisting force
being pushed into it from over the opening.
The following change has been made to the output of drag strut forces in the Collector Forces table of the Design Results (formerly Drag Strut Forces)
c) Negative Compression forces.
The magnitude of the drag strut a force in compression is shown with a negative sign. The legend explains that positive numbers are in tension, negative ones in compression.
5. Default Standard Walls
The following changes have been made to the Standard Walls that are included by default in Shearwalls
a) Wall Framing Species (Change 31)
The wall stud species for all six standard walls has been
changed to S-P-F from D.Fir-L, as spruce-pine-fir is more
commonly used than Douglas Fir-Larch. .
b) Nail Size (Change 31a)
The nail size for the three exterior
standard walls has been changed to unknown from 8d. Because these
walls have unknown sheathing thickness, a known nail size limits the sheathing
sizes that can be selected, which is not desirable for a default wall.
6. Default Size for New Openings (Change 51)
Now, the default size for new openings is 3 feet with an offset of 2.5 feet from bottom of the wall, approximating the size for a window. Previously the default size for a new opening was 6.75 ft approximating the size for a door.
7. Wall Shading Legend for CAD Drawing (Bug 3290)
In Plan View legend for the CAD Import action shows segmented walls as diagonal rather than solid, as they appear that way in this view in order to reveal the CAD drawing. The legend item Aspect factor is no longer shown in this action as it is not relevant
8. Options Settings and Show Menu
The following changes have been made to the Display items in the Options Settings, and/or the corresponding items in the Show menu, which control program elements to display or output.
a) Elevation View (Change 57)
For the Show menu that appears while Elevation View and/or the Elevation View column in the Options Settings,
i. Center of Loads and Center of Rigidity
Checkboxes for Center of loads and Center of rigidity have been added under Elevation view in the Options Settings. Previously, they had only been in the Show menu
ii. Aspect Ratio
Aspect ratio has been moved to appear below Segment numbers.
iii. Nailing Information and Legend
The Nailing information used to mistakenly hide
and show the legend. It has now been renamed Legend. Nailing information
now is shown and hidden via the Sheathing information item.
iv. Shear Force and Capacity
An item has been added to show or hide the design shear force and combined capacity information, which previously were always shown. This allows the entire material specification \to be removed if all Show menu items are turned off.
b) Spelling of Story (Change 20c)
For the Show menu that appears while viewing Design Results and/or the Design Results column in the Options settings, the word Story was misspelled as Storey for both wind and seismic story drift. This has been corrected.
The following changes have made to the Design Settings input
a) Reference to Wind Serviceability Provision (Change 85)
The ASCE reference in the Wind serviceability data group title has been changed from ASCE 7 CC.1.2 to ASCE 7 CC.2.2. CC.1.2 was the reference in ASCE 7-10. Also, the word limit is now capitalized.
b) Location of Shearline
Materials Checkbox (Change 85)
The
checkbox titled All shearwalls on
shearline have identical materials and construction was moved into the Design procedures group box.
c) Brackets in Moisture Percentage (Change 85)
Brackets have been added to the text appearing underneath the Fabrication and In-service inputs in the Service conditions group box. The text e.g. <=19% and >19% is now changed to (<=19%) or (>19%).
d) Unnecessary Word
“Calculation” (Change 85)
The word calculation has been removed Perforated shearwall Co factor calculation.
e) Hyphenation of Gypsum-based (Change 27)
A hyphen has been included in gypsum-based in the Design Setting for excluding walls sheathed entirely with these materials, and in warning messages that appear when wet service conditions are set for disallowed materials.
10. Shear Results Table Legend
The following changes have been made to the Shear Results Table of the Design Results
a) vmax Definition (Change 65)
For perforated walls, the definition of vmax in Legend to the Shear Results table has been changed to collector and in-plane anchorage force from collector shear force, because this force also applies to the to anchorages from the wall to the floor for both shear force ( SDPWS 4.3.6.4.1.1) and uplift (4.3.6.4.2.1). Shearwalls does not, however, specify these anchorages.
b) FHS Explanation
The explanation of FHS as “full height sheathing” as been moved from the definition of vmax to that of v, where it first appears.
c) Criterion Spelling
The misspelling of the word criterion as criterior has been corrected.
11. Seismic Zone Restrictions in Seismic Information Table
The terminology Seismic Zone has been changed to Seismic Design Category in the small section under the Seismic Information table listing restrictions based on Seismic Design Category.
12. Wind Load Generation Details Output Changes
Consistent capitalization of Kzt and Kz, rearranged a bit.
13. Output of All-heights Velocity Pressure q in Detailed Wind Results (Bug 3584*)
For the All-heights wind load generation method, the Wind Load Generation Details load table showed a single pressure velocity q value for all building elements, wind directions, and building levels, and for C&C and MWFRS loads, whereas according to ASCE 27.3 the MWFRs q values should have been different for leeward vs windward wind directions. For windward wall loads, they depend on the height of the element.
For example, for a simple gable roof structure with only W-E roof loads generated, the MWFRS q was 16.4 psf when it should have been 8.8.
In another example which was a 2-story building with loads generated on all surfaces, the q values shown were 52.3 psf for all elements, levels, and directions, and for both C&C and MWFRS loads. However, the wall loads on the lower level were 25.6 psf in the leeward direction and 31.4 psf in the windward direction. These values were different on the 2nd level, and the roof values were also different, as expected.
All other values that appeared in the MWFRS loads table, except for design wind pressure p on windward walls, were the same for both versions. For one surface, windward pressure was 17.39 psf when it should have been 21.37 psf.
This problem therefore was a display issue only which did not affect the magnitude of loads generated on the structure and has been corrected.
14.
Redundancy Factor in
Opposing Directions * (Bug 3428)
When the program applied a rho factor of 1.3 for seismic
design from ASCE 12.3.4 to the design force on a shearline, it did so only for
forces in the East -> West and South->North directions and not in the
opposite direction.
This happened whether the factor of 1.3 was set in the
Site Information, or "calculated" was set and the program detected
the value.
The incorrect forces appear in the Shear Results table
and the Deflection tbale of the Design results, where in most cases rows for
both directions are created when only row should be.
As the program designs for the highest force in either
direction, an incorrect design could only occur if design forces before rho
applied were higher in the North-South direction than in the South-North
direction, and this is unlikely. It can only occur for deflection-based force
distribution where asymmetric configurations of hold-downs creates different
deflections in opposing directions, and the difference in forces is not often
great in these cases.
Shearwalls 11.2 – December 16, 2012
Important: Shearwalls 2019 and Version 11.2 were
released simultaneously, so please consider both this list and the changes
listed under Shearwalls 2019
as the record of changes for Shearwalls 2019. Changes listed under
Shearwalls 2019 are not in Version 11.2.
1. Automatic Detection of Redundancy Factor (Bug 3405)
In Design Settings, when the setting for all shear walls on shearline having identical materials was not set to be true, the program was not detecting the violation of condition a of ASCE 12.3.4.2, which is one of two conditions that must be untrue if the redundancy factor is set to 1.3 rather than 1.0. Therefore, dissimilar shear walls, a redundancy factor was never applied to seismic shearline forces when the redundancy input was set to Calculated (rather than 1.0 or 1.3) in the Site Information. This has been corrected.
Note that Calculate redundancy and not to force identical materials are the default settings.
2. Zero Design Force for Same Materials on Both Sides (Bug 3361)
For walls with same materials on both sides of the wall and unknown sheathing thickness, the program assigned zero force to the wall while designing, so that any wall would pass design and there was zero wall deflection. The zero force appears in the deflection results, the shear design results, and no design shear shown at the bottom of the wall in the Elevation view drawing.
3. Data Related to Hold-downs in Standard Wall Groups (Bug 3409)
- If Design in Group was not selected, the wall would no longer be designated as being one the Standard walls. Extra design groups would be created for all the walls affected.
- If Design in Group was selected, the change would be propagated to all other walls that were part of the Standard wall group.
a) Hold-down Data
The following data were not available for selection in Standard Wall mode, but were being treated as Standard Wall parameters:
- hold-down model,
- number of brackets,
- whether to apply the same hold-down to the openings.
b) No. of End Studs (Bug 3307)
The number of end studs, which is used only for hold-down design, has been removed from the standard wall definition for the purpose of design grouping but is retained in the Standard Wall mode of Wall Input View for the purpose of creating default walls.
Hold-down related information is no longer included in the Standard Wall definition because hold-downs are designed separately from walls, and it is desirable to group walls according to wall materials only.
4. Importance Factor for Diaphragm, Drag Strut and Out-of-plane Forces (Bug 3399)
The importance factor used for the maximum and minimum diaphragm design force from ASCE 12.10.1.1 (Eqn.'s 12.10-2 and 12.10-3), and for the out-of-plane of wall Forces using 12.11.10, was always 1.0 rather than the importance factor corresponding to the Risk Category selected in the site dialog.
The incorrect diaphragm design forces were used for drag strut design and appear in the Seismic Information table. The incorrect out-of-plane forces appear in Elevation View.
5. Unblocked Factor for Deflection Nail Slippage (Change 45e)
The program was not applying the unblocked factor Cub from SDPWS Table 4.3.3.2 to the nail slippage term in the non-linear 4-term equation C4.3.2.-1. SDPWS 4.3.3.2 says to divide v in the 3-term equation 4.3-1 by Cub, but there is no direct guidance on whether or how to apply it to the 4-term C4.3.2.-1. The program applied the factor to the shear and bending terms in the 4-term equation, but as the nail slip en term includes v only indirectly, it was not applied to nail slip.
Since Commentary equations C 4.3.2.2.-1 and -2 indicate that it should be considered a stiffness -reducing factor, we decided to divide the deflection due to non-linear nail slip by Cub, rather than apply it to the v before it is raised to a power in the determination of en.
6. Deflection Convergence for Close to Zero Force on Segment (Change 45g)
The convergence routine for equalizing deflections along the shear wall as required by SDPWS 4.3.3.4.1 sometimes left a small residual on a segment that should not attract any force, causing the program to report that it could not equalize deflections. The program now zeroes out the force if it is less than 0.05 plf, that is, what appears as 0.00 in the output. Note that it adds this small force back into the pot to be redistributed to other shearlines, so it isn’t leaking forces if several segments are zeroed out.
7. Shear Stiffness Gvtv for Unknown Sheathing Thickness (Bug 3269)
When determining the shear-through-thickness Gvtv from SDPWS Table C4.2.2A used in the shear term of the 4-term deflection equation in C4.3.2-1, and indirectly via determination of Ga in the 3-term equation 4.3-1, when the sheathing thickness had been left unknown, the program was using the Gvtv for the thickest sheathing option, or 23/32”, rather than the thickness for the sheathing being designed. This caused a non-conservative error in the shear term of the 4-term deflection equation of about 5%. The shear term is usually a small component of the overall deflection.
B. Load Generation and Force Distribution
1. Vertical Distribution of Rigid Diaphragm Shearline Forces (Bug 2733)
We have changed the way the program incorporates forces from shearlines on upper levels in the rigid diaphragm analysis on the level below.
a) Previous Procedure
In versions before Shearwalls 11.2:
i. Seismic and Non-Torsional Wind
For seismic design, and the non-torsional wind cases (ASCE Envelope Procedure form Figure 28.3-1 and ASCE Directional Procedure, Case 1 from Figure 27.3-8) Shearwalls included the unfactored shearline forces derived from flexible diaphragm analysis on the level immediately above and added them to the applied loads on the level for which rigid analysis was being performed. The shearline force was then factored by the 0.6 load combination factor.
i. Torsional Wind
For ASCE Directional Case 2 loads, Shearwalls included the applied loads from all levels above and added them to the applied loads on the level for which rigid analysis was being performed. The shearline force was then factored by 0.6 for wind design
b) New Procedure
For both wind and seismic design, the shearline forces arising from rigid diaphragm analysis from the level immediately above are applied to the rigid diaphragm analysis on the floor below. For each shearline, the worst case of forces from positive and negative accidental eccentricity on the level above are those which are transferred.
c) Background and History
i. Rationale for Previous Procedure
When the rigid diaphragm procedure was implemented along with multi-story analysis in version 2002 of the program, there was concern that the torsional effect of the accidental eccentricities applied on the level above should not be carried through to the level below for two reasons:
1. Probability of Simultaneous Occurrence
It was thought that accidental eccentricity is entirely to account for inaccuracies in the distribution of mass in a structure, and that it was unlikely that these inaccuracies or variabilities would occur on each level and in the same direction.
2. Compounding of Accidental Eccentricity
There was a concern that the eccentricity would unnecessarily compound, that is, the effect of eccentricity on the level above creates amplified forces that would be further amplified by the eccentricity on the level below.
2. Consultations
We received guidance at that time that it would be acceptable to apply loads derived from flexible forces on the floor above to rigid analysis on the level below.
ii. Use of Applied Loads for Non-torsional Wind Design
The Case 2 Directional torsional wind requirement was determined to apply to flexible diaphragms and added to the program for version 10, in 2013. In order to avoid compounding this eccentricity, applied loads on the levels above were used in lieu of shearline forces. This was an internal change only, there is no effect on the resulting torsional moments.
d) Reason for Change
i. Probability of Simultaneous Occurrence
ASCE 7 C12.8.4.2 says that it is “typically conservative to assume that the center of mass offsets of all floors and roof occur simultaneously and in the same direction.” That is, as we cannot know for certain which levels and directions the accidental eccentricities occur in, it is best practice to assume they occur on all levels.
ii. Effect of Compounding vs Flexible Diaphragm Inaccuracy
Typically, accidental eccentricity adds approximately 10% force to the shearline experiencing the greatest effect. Compounding this effect on the floor below by adding 10% of 10% = 1% is not a significant increase and is much less than the inaccuracy that arises from using the flexible diaphragm forces from the shearlines above. Flexible diaphragm analysis can result in a markedly different distribution of force than the rigid diaphragm force, and by using flexible forces, the program was not transferring the inherent torsion from the floor above to the one below.
e) Consequences of New Procedure
i. Distribution of Non-torsional Direct Forces
The new procedure uses the direct forces due to shear wall stiffness on the level above, rather than those arising from flexible analysis. As we are assuming rigid diaphragms on all levels, this is a significant improvement in the accuracy of the procedure.
ii. Distribution of Inherent Torsional Forces
The new procedure transmits inherent torsional forces due to physical offset between the center of mass and center of rigidity, and these forces contribute to torsion on the level below. This is the correct procedure, as an object when subject to torque twists throughout its whole length. The old procedure did not transmit torsion between levels.
iii. Distribution of Accidental Torsional Forces
On each line, the program transmits the maximum force from positive and negative accidental eccentricity. As such, the new procedure will transmit the increase in force due to accidental torsion but will not transmit the torsional effect of that force, as the worst case of the positive and negative accidental torsions on opposite extremities of the structure tend to cancel.
We believe this is an acceptable compromise between the conservative procedure described in ASCE 7 C12.8.4.2, and the non-conservative procedure of not including accidental eccentricities from the floor above on the floor below at all.
2. Vertical Transfer of User-applied Seismic Shearline Forces (Bug 3467)
For All heights wind load generation procedure, when a wind shearline force was added directly to a shearline using the Add as a factored force directly… input in the Add Load input form, for rigid diaphragm analysis the force had an effect on only the level it was added on and was not being transferred below for inclusion in the torsional analysis on the level below.
This has been corrected in the course of implementing the changes in Bug 2733, above, Vertical Distribution of Rigid Diaphragm Shearline Forces.
3. Low-rise Wind Load Generation for Flat Roofed Buildings (Bug 3474)
In the case of buildings with flat roofs and on the upper level of the structure, the generation and distribution of low-rise wind loads using ASCE Fig 28.3-1 were incorrect in several ways. In such buildings, the longest direction of the building is considered to be the direction parallel to the ridge line for buildings with roofs. The following problems were identified and corrected
- Case A (transverse to long direction) loads were being generated on end walls, however such walls are not loaded in the ASCE model
- Some Case A loads were being created with the magnitude intended for Case B loads, and vice versa
- For torsional analysis of load Case B (wind force parallel to long direction), no force was being included parallel to the long direction
4. Shadowed Blocks with Roof Overhangs (Bug 3465)
For generation of wind loads, when a block with roof overhangs was adjoined to another block, the program would create loads on the roof the block was adjoined to in the portion shadowed by the block, even if the Exclude roof portion covered by other block checkbox in the Load Generation input was checked. This happened when using the load generation procedures for both low buildings and all other buildings.
The following problems pertaining to wall out-of-plane seismic force Fp from ASCE 7 12.11.1, which is shown in Elevation view, have been corrected.
a) Wall Weight in Calculation (Change 78)
The program was using only the weight W of ½ the wall height in the calculation Fp= max( 0.4 SDS Ie* W, 0.1W) when it should have been using the full wall height.
b) Display for Rigid Diaphragm Analysis (Change 79)
Fp is now shown for both rigid and flexible diaphragm analysis. Earlier, it was shown only for flexible analysis.
C. Building Model and Graphics
1. Multiple Wall Selection in Load Input View (Feature 252)
It is now possible to select multiple walls on which to apply loads in the Add Load dialog. Once walls are selected using the Control Key or Select All command, upon entering the Add Load dialog,
- Point loads cannot be selected,
- Apply to is disabled and shows Selected Walls,
- The From and To locations are blank and disabled,
- The Add as a factored force directly to the shearline is not available
Loads are then added on all selected walls, with the Magnitude From and To being the load magnitude at the start and end of each wall.
2. Update of Roof Joining (Bug 3377)
For multiple blocks, the program occasionally failed to update the roofs according to the input in the data group Construction in Roof Input View in the following ways:
a) Disabled Joined Selection
If there is another block that a roof could join to, the Joined selection was sometimes disabled so the operation was impossible.
b) Gable and Hip Selections
When roofs are joined in the N-S direction, the Gable and Hip selections sometimes had no effect and the roof remained joined when selected.
These have been corrected.
3. Outsize Openings after Change of Wall Height (Bug 3347)
When the wall height is changed in Structure input, the program now adjusts the top of any openings to ensure that they remain within the confines of the wall and removes the openings that would have no height if this is done.
4. Depiction of Non-full-height Segments in Perforated Walls (Bug 3383)
In Elevation view, non-full height segments, that is, those that do not meet aspect ratio limits in ASCE 7 Table 4.2.4, were not shown in grey out as they are for segmented walls. They are now greyed out, because such segments do not contribute to shear resistance and are not included in the summations of segment lengths used for Co factor calculations (4.3.3.5), hold-down forces (4.3.6.1.3), and in-plane shear anchorage (4.3.6.4.1.1).
5. Drawing of Vertical Element for Offset Openings in Elevation View (Bug 3463)
When the end of an opening on an upper storey is over the interior of an opening on the floor below, the drawing in Elevation view of the vertical element extending from the bottom of the upper floor joist to the top of the opening was no longer visible because it was obscured by the gray shading over non-full-height sheathing segments that was introduced with version 11.
This has been corrected.
6. Rounding of Dimension Line in Elevation View (Change 70)
7. Levels Indicator for One-storey Structure (Change 249)
For a one-story
structure, the Levels indicator is
shown in the Extend to field. Now it is shown in the Current
level and the Extend to field is
invisible in this case.
8. Display of Center of Loads and Center of Rigidity (Change 251)
The following changes have been made pertaining the symbols that appear in Plan View in the Load Generation and Loads and Forces actions showing the Center of Load and Center of Rigidity for Torsional Analysis
a) Show Menu Item Activation
The show menu items for center of load and center of rigidity were always disabled in Loads and Forces view, only becoming active in Load Generation view. This has been corrected and they are active in both views.
b) Center of Loads for No-load Cases
When there are no
loads in a direction, such as for low-rise wind load Case A, the program showed
the Center of Load in the direction without loads at the zero location, making
it difficult to notice. In this case, it has now been moved to where the Center
of Rigidity is located.
c) Overlapping Symbols
When the center of loads and center of rigidity are in the same place or close to it, the symbols CL and CR now longer overlap.
9. Color of Selected Shearlines (Change 96)
When a wall is selected in Plan view and turns orange, the other walls on the shearline turn a darker colour of orange (or brown). Previously they were purple.
10. Directional Method Nomenclature in Plane (Change 247)
The word Direction indicating the ASCE 7 load generation method in the Plan View legend has been changed to Directional in accordance with ASCE 7 Chapter 27 nomenclature.
11. Overlapping Legend Text in Elevation View for Perforated Walls (Bug 3245)
For narrow Elevation view windows, and when the hold-down and/or drag strut Design Setting is set to Shearwall capacity, the Legend heading Factored Forces overlapped with perforated wall aspect ratio information shown under the walls.
1. Re-appearance of Plan View Input Forms (Change 37)
When in Plan view and
you close the input form, e.g. Opening
Input, either by the exit button on the form window or by the Input Form icon in the toolbar, then go
to another Plan view action, e.g. Roof Input, and return, the input form for
the original action now re-appears. Previously it remained invisible and some
users had difficulty making it reappear.
2. Separate Load Generation Details and Torsional Analysis Reports (Changes 1 and 2)
The program now displays three separate reports for detailed wind and seismic load generation and torsional analysis calculations, rather than all three in one report as before, and outputs three files with this information rather than one.
a) Toolbar buttons
The toolbar button that previously showed the word log and is called Load Generation and Torsional Analysis Details has been replaced by three buttons, one which shows three single-ended arrows and is called Wind Load Generation Details, another showing three double-ended arrows and is called Seismic Load Generation Details, another which shows a semi-circular arrow and is called Torsional Analysis Details.
The button for the primary design results has been changed to convey the tabular nature of that output.
b) Menu Items
The File menu item Log File has been removed, and the following files are now accessed from menu items in the View menu.
Wind Load Generation Details
Seismic Load Generation Details
Torsional Analysis Details
The word View has been removed from Design
Results View, for consistency with
these menu items.
c) File Output
The file with extension .log file has been replaced by three files with extensions .sws, .sww, and .tor.
d) Operation
Previously, the combined file was output when loads
were generated, then appended to after Design button was pressed when the
torsional analysis is performed. If loads were then regenerated, the torsional
analysis results were lost. Other synchronization problems occasionally
occurred.
Now, the Load Generation Details files are output when loads are generated and Torsional
Analysis Details when the design is performed, eliminating any interference
between the two.
e) Headers
The titles and headers to the load generation and
torsional analysis results have been redesigned to achieve a consistent format
across all three intermediate output files, torsional analysis, wind load
generation, and seismic load generation. In the subheadings giving the load
generation procedures, Wind Load Generation and Seismic
Load Generation have been set to all capitals to make them stand out.
f) Getting Started Steps
The 14th and final step in the
introductory Getting Started window
has been modified to refer the Torsional
Analysis Details, Wind Load
Generation Details, and Detailed
Shearwall Design output reports rather than the log file.
3. Crash after Sheathing Material Change (Change 62)
Starting with version 11.1, a crash occurred if the exterior sheathing material of the wall was changed after loads were generated. Sometimes it happened immediately, other times after other program operations were performed. This has been corrected.
4. Torsional Analysis Report for Flexible Diaphragm Wind Design (Change 55)
If a project is run such that torsional analysis is required, then the inputs are changed such that it is not and run again, the program retained the Torsional Analysis Details from the previous run. If torsional analysis is not required because the Rigid analysis option is not selected and there are only seismic loads on the structure, the torsional analysis report no longer appears.
5. Link to Video Tutorials in Help Menu (Change 29)
The following link has
been added to the Help menu for a
user to navigate to a video tutorial from within the program. (http://cwc.ca/woodworks-software/support-and-training/tutorials/).
6. Crash on Corrupted or Empty Hold-Down Database (Bug 3375)
If the hold-down database was empty or corrupted, a crash occurred on program start-up. The program now re-installs the original database if it encounters a corrupt or empty one. It was possible to avoid the crash by deleting the corrupted hold-down database file.
7. Elevation View Crash for Non-full Height Shearlines (Bug 3454)
Occasionally, when a shearline in a structure had a no full-height-sheathing segments, the program would crash upon entry to Elevation view.
8. View Style in Design Results Window (Change 25)
After running design, thee Design Results are now shown in the last selected view style, Wide View or Preview. Previously it returned to Preview each time. The program still defaults to Preview on the first design run.
9. “Getting Started” Steps (Change 103)
The instructional steps that appear when the program is run or “Getting started” is invoked from the toolbar have been revised, clarified and updated. Some of the more significant changes are:
a) Default Values
A “Step 0” has been added suggesting setting defaults for building elements, and the subsequent steps indicate how those defaults are used to create the structure.
b) Edit Walls
Explanations of the ability to change the location and size of walls via the wall input form, the selection of Standard Walls, designing for unknowns, and designing as a group have been added.
c) Edit Hold-downs
A Step 7 has been created for editing hold-down device information, by moving instructions from other steps.
d) Generate Loads
An instruction to set the Wind Load Generation Procedure has been added, and the procedure of creating seismic loads in stages with self-weights on each level explained more clearly.
e) Add or Edit Loads
The need to add dead loads to counteract overturning, and wind uplift loads, has been emphasized. An explanation of changing building masses and returning to regenerate loads has been added, as has the case of not generating loads and adding loads to check a single shearline. The unusual case of modifying generated loads has been removed.
f) Design
Several design settings have been added to the recommendation to set the Rigidity and Deflection options before designing. The mention of design processing time has been removed, as it is no longer a major issue.
g) Accept or Adjust Design
A Step 15 has been added for the Accept Design feature.
h) Detailed Results Output
The step formerly called “Log File Output” has changed to View Detailed Results, and lists the separate buttons and associated files for wind load generation, seismic load generation, and torsional analysis, that used to be in one file
10. Options Settings and Show Menu
The following changes have been made to the Display items in the Options Settings, and/or the corresponding items in the Show menu, which control program elements to display or output.
a) Design Results
For the Show menu that appears while viewing Design Results and/or the Design Results column in the Options settings.
i. Hold-down Design and Collector Force Tables (Bug 3228)
The inclusion of the Hold-down Design table and Collector Forces (formerly Drag Strut Forces) table in the Design Results output is now controlled by separate items in the Show menu and in the Options settings. Previously they were both controlled by a single item in the Loads and Forces settings.
ii. Wind Story Drift and Deflection (Change 20b)
b) Wind Direction in Loads and Forces Settings (Bug 3240)
In the Loads and
Forces settings, the check boxes labelled Southwest, Northeast, Southeast,
Northwest have been changed to show Wind from Southwest, etc.
c) Drag Strut Spelling (Change 57f)
In the Show
menu, under Forces, Dragstruts has been changed to Drag Struts.
11. Warning and Informational Messages
The following changes were made to the text in messages:
a) Warning Message for Rounded Opening Input Values (Change 48)
The warning message about opening input being rounded to the nearest snap increment, identified the input by long phrase that did not make sense in the context of the warning. It has now been abbreviated to briefly identify the input, e.g. Offset from edge.
Square brackets around the input value have also been removed.
b) Loads and Forces Warning Message Misalignment (Change 4)
The warning message when Loads and Forces view for the first time had misaligned bullet points. This has been corrected.
c) Hip Roof Wind Load Generation Message (Bug 3294)
d) R and Cd Warning Message for Gypsum (Change 66)
In the warning message that appears when a greater value
of Response modification factor R and Deflection amplification factor Cd are
input in the Load Generation Site Information for a direction having
non-wood-panel shear walls, mistakenly structural wood panels is output instead
of non-wood panels and this has been corrected.
12. Change of Spelling in User Interface (Change 111) *
All references in the user
interface to “shearwalls” and “shearlines” have changed to “shear walls” and
“shear lines”, as this is the correct spelling and the one used by CSA O86.
The following changes have been made to the Wall and Shearline Input form and/or the Openings Input form:
a) Shearline Selection in Wall Input View (Change 24)
The Shearline input is now disabled if there is no choice other than Auto. This input allows you to select the shearline a wall belongs to if the walls are within the allowable shearline offset of walls defining two or more shearlines. As the default offset in the Design Settings is only 6”, this rarely occurs, and the use of this input was unclear to some users.
b) Relative Rigidity for Standard Walls (Change 63)
The input for relative rigidity appearing in Wall Input view when in Standard Wall mode has been removed. You can no longer enter this value when modifying a regular wall, and now serves only to show the rigidity of the designed wall relative to others. It has no meaning for Standard Walls.
c) Irrelevant Warning Message for 1-ply Gypsum Wallboard (Change 93)
A warning message about nail length limitations from an irrelevant design code appeared when the
mouse was clicked anywhere in the input form, when Gypsum Wboard 1-ply
was selected the sheathing material and Drywall screws, fastener type,
with the fastener Size in focus, This has been corrected
d) Hold-down Information
The following changes have been made to the inputs of hold-down information.
i. Hold-down Selections for Perforated Walls (Bug 3267)
For perforated walls and for the new force-transfer walls, the Apply hold-downs to openings checkbox in Wall Input form, and all input in the Hold-down data group in the Openings Input form, are now disabled because hold-downs are not placed at wall openings for these types of walls.
ii. Hold-down Dropdown Box Style (Change 82)
The hold-down model input has been changed from an editable drop-list to a noneditable list, as a hold-down typed into this input would not necessarily match with an existing one in the database.
The following changes have made to the Design Settings
a) Disabled Worst-Case Rigid vs Flexible Diaphragm Setting (Change 54)
The check box for Worst-Case rigid vs flexible diaphragms was disabled and showing as selected if only one of Rigid or Flexible Analysis was selected in the Structure input. Now it is shown as not selected (empty) in this case.
b) Reset Original Moisture Conditions (Change 46)
The Moisture conditions did not reset to their original values, 15% for Fabrication and 10% for In-service, when Reset original settings was pressed. This has bene corrected.
c) Hold-down and Drag Strut Data Group (Change 84)
The date group Collector forces based on in the Design Settings has been renamed Forces based on , as the definition of Collector in ASCE 11.2 includes drag strut as a synonym, so that hold-downs cannot be considered a “collector” This change has also been reflected in the Design Settings output.
The redundant word “forces” has been removed from the
column headers in the data group which now say Hold-downs and Drag struts.
d) SDPWS References in (Bug 3312)
In the SDPWS Deflection Equation data group, the SDPWS reference for the 3-term equation option was 4.2-1, the equation for diaphragms, and has been changed to 4.2-1, the one for shear walls.
The reference for the 4-term equation was listed as C4.3.2-2 , the Commentary reference for 3-term, and has been changed to C4.3.2-1, the correct equation for 4 term.
The references have also been corrected in the Design Settings output table. The correct equations were used in design; this was only a display issue.
e) Apply height to-width ratio to… Setting (Change 85a)
The data group Apply height to-width ratio to…has been removed from the Design settings,
as it applies only to multi-block low-rise structures, which are not permitted
in version 11.2.
Note that Shearwalls 2019 incorporates
these structures and includes the setting Low-rise
height-to-width limit based on….
f) Default Ignore Gypsum Setting (Change 106)
The option to ignore the contribution of gypsum-based
materials for narrow wall segments is now checked by default, as it is normally
advantageous to do this.
Other settings changes:
g) Hold-down Settings Input Field Sizes (Change 244)
Sime of the inputs in Wood Properties and Construction Details section of the Hold-down settings were too small to
show typical data without scrolling and have been enlarged.
h) Save as Default for New Files (Change 255)
The following settings were not being saved as defaults when Save as default for new files was selected.
- Line 4 of company information under Company Information
- Worst-case rigid vs. flexible diaphragms in Design Settings
This has been corrected.
i) Reset Original Settings (Change 257)
i. Moisture Conditions
Fabrication and In-Service Moisture in Design Settings were not being reset to their original value after you reset original settings.
ii. Snap Increments
The Snap Increments input in Plan View and Elevation View settings was not being re-enabled if the Display gridlines was not checked before you reset original settings. It is now enabled after the reset because Display gridlines is checked in that case.
The following changes have been made to the Site Information input form
a) Default Fa and Fv For Site Class F (Change 26)
If Site
Class F is selected in the Site Information and the Fa and Fv values now show
zeroes rather than the values from the last site class selected; and if you
exit the dialog without the program now issues a warning message asking you to
enter non-zero values. If OK is
selected, you return to the input dialog; If Cancel is selected, the changes are reverted.
b) Link to Wind Speed Map (Change 42)
The link to the wind speed map in the Site Information has been updated to refer to the new web address https://hazards.atcouncil.org/ for the Applied Technology Council’s Hazards by Location website. The previous site expired on June 30, 2018. Note that as of March 21, 2018, it is a beta release of the website
c) Link to Seismic Data Map (Change 91)
The reference to the seismic maps containing site coefficients S1 and SS in the has been changed from https://earthquake.usgs.gov/designmaps/ to https://seismicmaps.org/ . The new link is from the SEAOC/OSHPD Seismic Design Maps Tool that is referenced in the web site from the old link, the U.S. Geologic Survey (USGS) Earthquake Hazards site, however it is amongst many other links on that site and it was not clear which one to choose.
a) Update of Values (Change 8)
In Generate Loads dialog, the following values reverted to their original values after being edited and you clicked anywhere outside the box before generating loads:
Seismic loads:
- all self-weight text fields
- Horizontal projection check box
- Use wall self-weights…for Jhd calculations check box (Canada only)
Wind loads:
- line/area load radio buttons
- C&C wall loads check box
The program now retains all the inputs.
b) Update of Low-rise Hip Roof Method Selection (Bug 3294)
The choice of using low-rise side panel coefficients or using ASCE -7 Fig. C28.3-2 was sometimes disabled even when there were hip roof panels on the structure. This has been corrected.
5. Load Input and Add Load Dialogs
a) Openings in Floor Area Note (Change 7e)
A note to enter a mass with negative magnitude to represent an opening in the floor now appears at the bottom of the Add a New Load box when Building mass and Area load are selected, to make users aware of this possibility.
b) Add Load to Selected Wall (Change 254)
If no wall was selected and Selected wall was chosen in the Apply to... combo box when adding a new load, a large value automatically appeared in the From X= and To X= fields. Furthermore, you are allowed to enter a load which appeared on a random building face.
The program has been changed to revert to the previous Apply to... selection in this case.
c) Wind Uplift Loads on Selected Walls (Change 95)
For wind uplift loads, in the Application input of the Add a New Load dialog box, you can now add the loads to selected walls. Previously only the full wall line was available.
The following change has been made to the Design Settings table of the Design Results output.
a) Deflection Analysis not
Performed (Change 83)
In the line saying Deflection
Equation in the Design Settings output, if Include deflection analysis is unchecked in Design Setting, No deflection analysis is shown rather
than Never or Always.
This is because the deflection equation is irrelevant if there is no deflection analysis; also, the Include deflection analysis setting was not previously reported in the output.
The following change has been made to the Sheathing Materials table of the Design Results output.
In the Sheathing Materials table of the Design Results output for OSB materials, the number of plies last selected for plywood was shown. As plies are irrelevant to OSB, a dash now appears.
The following change has been made to the Seismic Information table of the Design Results output.
a) Seismic Design Category Terminology (Change 68)
The section under the table called Seismic Zone Restrictions has been renamed to Seismic Design Category Restrictions in accordance with the terminology in the ASCE 7.
The following changes have been made to the Shear Design table of the Design Results output.
a) vmax Reference in Legend (Change 53)
The legend entry for vmax, the shear force for collector and connection design, now refers to SDPWS Equation 4.3-9 instead of the incorrect reference to 4.3-8.
b) Shear Force in Kips (Bug 3319)
In the Shear Results table, the shear force and allowable shear force were shown in lbs when kips were selected as the imperial force unit setting even though the table header showed kips. This was only a display issue; design was not affected. The values are now shown in kips.
The following changes have been made to the Hold-down Design table of the Design Results output.
a) Hold-down Model Number for Offset Perforated/Segmented Walls (Bug 3327)
In some cases of segmented walls on the lower storey and perforated walls above where the openings did not line up vertically, for one of the openings on the lower level the table did not show the hold-down model number, although design results were shown for the hold-down. This has been corrected.
b) Load Combination Note (Change 105a)
The first two notes under the table regarding ASCE 7 load combinations and seismic forces Eh and Ev have been combined into one note that makes the relation between the signs in the equations and the directions of the forces clearer. The ASCE 7 reference numbers have also been updated.
c) Anchor Bolt Note (Change 105b)
The note below the table giving anchor bolt washer size
requirements has been changed to indicate that the design of the connection
from wall to floor or foundation is
not performed by Shearwalls, and that anchor bolt requirements are from SDPWS
4.3.6.4.3. The previous note sometimes misled users into thinking that the
“shear” column in the table was for horizontal shear in the foundation anchors,
and not the overturning force in the hold-down.
Furthermore,
this note appeared for seismic design only, although the SDPWS requirements
apply to both wind and seismic. The new note is output for both.
The following problems with the reporting of the uplift t force for perforated walls from SDPWS 4.3.6.4.2.1 in the Hold-down Design table were corrected. These forces occur when perforated walls and openings in them on upper levels do not line up walls on the levels below.
i. t Force When Combined with Overturning (Bug 3326)
When an overturning force exists at the same
location, the program did not report the t component, so that the combined
forces did not equal the sum of the components. A new line is now shown below
the existing line showing the t component in the Shear column (but not
the Combined column), at a position labelled e.g. t @ Op 1.
ii. Isolated t Force (Bug 3326)
When the t force was the only component of
the hold-down force, the program previously output a line with the t force in the Combined column only at
a position labelled e.g.I Op1. It
is now in both the Shear column and Combined column at a position
labelled t @ Op 1.
iii. Legend (Change 13)
There was no explanation in the Legend of
the t forces that sometimes contributed to the Combined force, or what
was meant by I Op1, for isolated t forces. A legend entry for t @ Op n
has been added, referring to SDPWS 4.3.6.4.2.1.
e) Reporting of Hold-down Model for Offset Perforated/Segmented Walls (Bug 3327)
When there were segmented walls on the lower storey and perforated above, and openings do not line up vertically, openings on the lower level one of the ends did not have a hold-down model number listed in the Hold-down table when there should have beeen one when at the location of a tensile hold-down force. This has been corrected.
f) Perforated Wall Note (Change 105c)
The reference in the note regarding the perforated wall force should has been changed to SDPWS Eqn. 4.3-8, from SDPWS 4.3-9.
6. Components and Claddings Table
a) SDPWS Table Reference Number (Change 67)
The reference in the legend to SDPWS Table 3.21 for out-of-plane sheathing capacity has been corrected to 3.2.1.
7. Wind Load Generation Details
a) Hip Roof Wind Load Generation Method (Bug 3294)
The choice of using side panel coefficients or using ASCE -7 Fig. C28.3-2 for low-rise hip roof generation now appears in the Site Information section.
b) Terrain Exposure Constants (Change 74)
The misspelling of Terrain in Terrain Exposure Constants, and the alignment of the epsilon-bar constant have been corrected.
8. Seismic Load Generation Details
The following changes have been made to the Seismic Load Generation Details report (formerly part of the Load Generation Details report).
a) R and T in Site Information (Change 59)
In the Site Information section,
i. Repeated Note
Two separate notes indicated that the response modification coefficient R and period T are shown in the base shear table. The first has been removed,
ii. Response Modification Factor Symbol
The symbol for the response modification coefficient factor was mistakenly shown as Rd, Ro. This has been changed to R.
b) Base Shear Tables (Change 60)
i. Total Design Base Shear Table
-
The table has been renamed Total Design Base
Shear, from Calculation of the total
design base shear:
- Added note about manually entered seismic loads and forces not being included.
ii. Distribution of Base Shear to Levels Table
- The table has been renamed Distribution of Base Shear to Levels from Distribution of total design base shear to Levels
- Added note about manually entered seismic loads and forces not being included in the distribution.
- the alignment of column headings Csmax, Csmin, Cs and V have been corrected so they appear above the data shown. (Change 14)
9. Torsional Rigidity Jy Output for Rigid Analysis (Change 80)
The value displayed in the Jy column of the Torsional Rigidity line in of the Torsional Analysis Details report had some extra digits after the number making it much too large. This was only a display issue and the erroneous value was not used in the calculation.
Shearwalls 11.1 – May 15, 2017 – Design Office 11, Service Release 1
1. Wind Story Drift Design Setting (Change 232)
Because the newly added wind story drift limitations from ASCE 7 CC.1.2 can be difficult to meet and are not mandatory according to ASCE 7 Appendix C, a design setting has been added to activate the calculation of wind story drift, and Option setting and Show menu item to allow you to turn off the output of story drift output tables independently for wind and seismic design.
a) Design Setting
A new data group called Wind serviceability ASCE 7 CC.1.2 has been added to the Design Settings page. In it there is a new checkbox allowing you to control whether to calculate story drift for wind loads, and the existing setting to enter the drift limit as a ratio of storey height.
b) Options Setting
The Options setting
controlling which design results tables to view that previously said Storey shear table is now two settings Story shear – seismic and Story shear – wind.
c) Show menu
The Show menu now has two items – Story drift – seismic and Story drift - wind instead of just Story drift.
2. Perforated Shearwall Issues
Several problems associated with perforated walls, particularly with the capacity adjustment factor Co from SDPWS 4.3.3.5, were corrected:
a) Co Factors Greater than 1.0 using SDPWS Eq’n 4.3-5 (Bug 3220)
The program calculated Co factors significantly greater than 1.0 while using SDPWS Equation 4.3-5 (as opposed to Table 4.3.3.5), when there are narrow segments in the wall, because the SDPWS does not explicitly limit Co to 1.0. When there are no narrow segments to which an aspect ratio factor is applied, as per the note to the definition of ∑Li in 4.3.3.5, the minimum limit of h/3 the opening height ensures that Co can never be greater than 1.0, but it can be when the aspect ratio factor is applied.
This was particularly evident when there are no openings in the wall and no need for a perforation factor, but one was made anyway on the assumption that it would always be 1.0. The program now limits Co to 1.0, and does so even when there are openings, as we believe this to be the intention of the SDPWS.
b) Design Results Using Co Factor from Wall on Upper Story (Bug 3225)
Occasionally, the Shear Results output table displays the Co factor for a wall on the story immediately above a wall, rather than the correct factor for that wall, and shows a capacity and design ratio based on that factor. This is just a reporting issue, and these values were not used to design the wall or determine deflections and force distribution.
c) Truncated Perforated Shearwall Issues
The following bugs apply to the perforated shearwalls such that one or more openings in the shearwall have no full-height segments between them and one end of the wall, so that the non-full height segments and adjacent openings have been stripped from the wall for calculation of Co.
The problems are particularly evident when there are no openings left in the truncated wall and no need for a perforation factor, so that the Co factor should be 1.0, and the factors were showing up as any number.
The incorrect Co factors appeared in the shear results table and in elevation view, and were used in the calculation of shearwall capacity and hold-down forces.
These problems all been corrected.
i. Co Factor for Truncated Perforated Shearwalls Using Equation 4.3-5 (Bug 3231)
For truncated perforated shearwalls the value of the total opening area Ao in SDPWS equation 4.3-5 still included the length the openings that should have been ignored. The total shearwall length Ltot was calculated correctly by excluding the openings, leading to nonsensical values of Co.
ii. Co Factor for Truncated Perforated Shearwalls Using Table 4.3.3.5 (Bug 3232)
For seismic design of truncated perforated shearwalls, the total shearwall length Ltot in note 2 of Table 4.3.3.5 was sometimes including the length of the segments and openings that should have been ignored, whereas the sum of segment lengths ∑Li excluded them, leading to incorrect Co values. For wind design the correct Ltot was used, leading to inconsistent seismic and wind Co values.
iii. Uplift Force t for Truncated Perforated Shearwalls (Bug 3234)
Truncated perforated shearwalls were showing the anchorage uplift force t from SDPWS 4.3.6.4.2.1 on non-full-height segments that had been ignored in the calculation of Co.
This uplift force t appears in elevation view and is not used for other calculations and has no effect on shearwall design or force distribution. It has now been removed from these segments.
3. Gap in Building Footprint for Openings Extending to Wall End (Bug 3142)
This occurred when an opening was than extends to the very end of a wall, meeting a perpendicular wall. If the location of the wall with the opening is then moved, followed by moving the wall it meets, the gap is created.
This problem has been corrected.
4. Nonsensical Hold-down Forces under Monoslope Gable End (Bug 3217)
When a wall was underneath a gable end from a monoslope roof, the hold-down forces calculated were nonsensically large. This has been corrected.
5. Crash for Newly Opened Projects in Structure View (Bug 3210)
Occasionally, when project files were opened in Structure view, they did not allow the activation of the input form button and did not show the Structure Input form. Upon moving to any other view, the program would crash.
This problem could be avoided by pressing the Structure input button, after which the program operated as it normally does. The program no longer crashes when this happens, but it is still necessary to click the Structure button to view the Input form.
6. Interaction of Ignore Contribution and Allow 3.5:1 Aspect Settings (Bug 3233)
The following bugs pertain to the disabling and re-enabling of the Design Setting Ignore contribution of … Gypsum-based materials … combined with wood structural panels … based on the state of the Allow 3.5:1 aspect ratio setting,
a) Dependence on Ignore for Seismic Design Setting
The disabling/enabling happened only when the Ignore contribution of … All gypsum materials …seismic design setting was unchecked. This was the behaviour of the corresponding settings for the previous version, but with the SDPWS 2015 implementation, these settings should now be independent. This setting is now enabled whenever Allow 3.5:1 aspect ratio is checked.
b) Greying of Text
When the checkbox is disabled, the program now still shows the text explaining the setting, instead of greying it out.
7. Display Settings Names (Change 231)
The word “table” has been removed from several Options Settings in the Display design results group, as it had been inconsistently applied to some design results tables and not others. The setting that previously said Materials table now says Sheathing/framing materials; in all other cases the word “table” has just been excised.
8. Ignore Non-wood-panel Data Group Title (Bug 3219)
The data group title Ignore non-wood-panel contribution… has changed to Ignore contribution of…. so that the elision of the title and the checkbox text, which had been changed for the 2015 SDPWS implementation, now makes grammatical sense.
Shearwalls 11.0.1 – December 22, 2016 – Design Office 11, SR-a
This
version released to address the following problems:
1. Sporadic Failure of 3-Term Deflection with Non-FHS Segments (Bug 3209)
When the setting "Rigidity for shear force distribution based on… is set to use the deflection of wall segments and the 3-term equation is selected for the SDPWS deflection equation setting, and there are non-full-height sheathing segments present, sometimes the forces were distributed in an inconsistent and unpredictable manner from one design to the next. This affected the distribution of forces along the shearline, the distribution of forces to the shearlines for the rigid distribution, and ultimately shearwall design. This issue was due to random problems with memory allocation in the computer, and has been resolved.
2. Disregard Height -to-width Limitation Setting in Files from Previous Versions (Bug 3208)
For projects made with previous versions to version 11, if the Disregard shearwalls height to width limitations had been set, the Plan View and Elevation View elements relating to aspect ratio did not appear, and upon design the program issued a Windows error message and froze.
This setting was removed for v11, but if you Reset Original Settings, the program stabilized so that the user interface elements would appear and you could run a design. In any event, the problem has been fixed and no longer occurs in version 11.0.1.
Shearwalls 11 – November 21, 2016 – Design Office 11
The
major features implemented for this version are
Update to SDPWS
2015, NDS 2015, and IBC 2015, including
Revised
combinations of sheathing materials along a shearline and on opposite sides of wall
Perforated
wall length adjustment factor and calculation method options
Improvements
to the operation and display of Elevation View
Update
of Simpson hold-down database
Story
drift limitations for wind loads
3-term
SDPWS deflection equation
Numerous
other improvements have been made to all areas of the program. The following is
an index to descriptions of the changes listed below.
1. Standards Updated (Feature 229)
2. References to the Design Standard Editions
3. References to the Design Standard Clauses
1. Aspect Ratio Factors and Adjustments
2. Aspect Ratio Length Adjustment for Perforated
Walls
3. Same Materials and Construction on a Shearline
4. Sheathing Combination Rules
5. Perforated Shearwall Calculation Method
6. Hold-down Database Update (Feature 202)
7. Out-of-plane Sheathing Capacity
8. Bug Fixes and Small Improvements
1. Storey Drift Limitations for Wind Loads (Feature
223)
2. 3-term vs. 4-term Deflection Equation (Feature
211)
3. ASD Deflections for MWFRS Wind Loads
4. Fiberboard Deflection Factor
5. Bug Fixes and Small Improvements
1. Shearwall Rigidity Settings
2. Ignore Non-wood-panel Contribution
4. Disregard Shearwall Height-to-Width Limitations
5. All Shearwalls on Shearlines have Identical
Materials
6. 3-term vs 4-term Deflection Equation (Feature 211)
7. Perforated Shearwall Co Factor Calculation
(Feature 171)
8. Story Drift Limit for Wind Loads (Feature 223)
9. Moisture Condition Category (Change 218)
1. Zoom and View Settings (Feature 216)
2. Segments, Aspect Ratios and Aspect Ratio Factors
(Feature 77)
3. Dimension Lines (Feature 79)
4. Shading of Non-shear-resisting Segments (Feature
56)
5. Display of Roof Line and Gable End (Feature 228)
6. Multi-storey Selected Walls (Feature 228)
7. Bug Fixes and Small Improvements
1. Wall Depiction in Plan View
2. Centre of Mass and Center of Rigidity (Feature
218)
3. Design Case in Plan View (Feature 83)
5. Bug Fixes and Small Improvements
G: Input and Program Operation.
1. Dissimilar Materials along Shearline
2. Link to Wind Velocity Web Site (Feature 213)
3. Log File in Viewer (Feature 208)
4. “Getting Started” Steps Display (Change 181)
6. Bug Fixes and Small Improvements
4. Shearline, Wall and Opening Dimensions Table
9. Hold-down Displacement Table
10. Story Drift Table for Wind Loads (Feature 223)
13. Load Generation Results in Log File
14. Torsional Analysis Results in Log File
Version 11
of Shearwalls updates several design codes and standards used in the program.
The details of the associated changes to the program appear throughout the rest
of this list of changes; this section just identifies the design standards
changed.
1. Standards Updated (Feature 229)
The
implementation in Shearwalls of the
IBC has been updated from the 2012 edition to 2015, the NDS from 2005 to 2012,
and the SDPWS from 2008 to 2015
a) ICC International Building Code (IBC 2015)
Version
11 of Shearwalls implements the 2015
IBC, whereas Version 10 implemented the 2012 version.
IBC 2015
references the AWC Special Design Provisions for Wind and Seismic (SDPWS 2015)
for all design provisions*, whereas IBC 2012 referenced SDPWS 2008. Extensive
changes for the 2015 SDPWS edition were implemented, as described in b) below.
IBC 2015
continues to reference ASCE 7-10 for all wind and seismic load generation
procedures. Since both Shearwalls 10 and Shearwalls 11 implement ASCE 7-10, no
changes were needed for these provisions.
*except
those using staples, which are not permitted by SDPWS. Shearwalls does not
include staples, so all procedures in the program comply with IBC by complying
with SDPWS.
b) ANSI/AWC Special Design Provisions for Wind and
Seismic (SDPWS 2015)
The
SDPWS had been updated from the 2008 version to the 2015 version for Shearwalls
11. The most consequential changes are listed here and described in more detail
in later sections of this document.
i. Force Distribution Method and Aspect Ratio Factors
Deflection-based
distribution is established as the preferred method of allocating forces to
segments within a shearline. Capacity-based distribution is restricted to wood
or fiberboard shearwalls,
and a more stringent aspect ratio factor is applied to the strength of narrow
shearwall segments when it is used.
ii. Perforated Wall Aspect Ratio Adjustment
Previously,
the strength of a perforated wall was factored by the aspect ratio factor for
the narrowest segment in the wall. Now, the length of wall used to determine
the Co factor is adjusted instead, leading in general to much lower
penalties for narrow segments.
iii. Same Materials and Construction on Shearline
The
design code clarified what is meant by the restriction to similar materials and
construction on a shearline, so that shearwalls with differing sheathing
thickness and nailing patterns are now allowed on the same line, as long as
they belong to the same class of materials (wood structural panels, gypsum
wallboard, fiberboard, etc.)
iv. Same Materials and Construction on Opposite
Sides of Wall
Although
it is not explicitly mentioned in the SDPWS, in communications with WoodWorks
AWC confirmed a that the same redefinition of similar vs. dissimilar materials
should be used when combining sheathing capacities from materials on opposite
sides of the wall.
v. Fiberboard Deflection for Narrow Segments
A new
provision requires that the deflection fiberboard segments with an
aspect ratio greater than 1:1 be increased by the square root of the aspect
ratio.
vi. Out-of-plane Sheathing Capacity
The
out-of-plane sheathing capacity for resistance to C&C wind loads has
changed for some materials.
c) ANSI/AWC National Design Specification for Wood
Construction (NDS 2015)
Version
11 of Shearwalls conforms to the NDS 2015, whereas version 10 conformed to NDS
2012. There are very few procedures in the Shearwalls program taken directly
from the NDS, as all shearwall and diaphragm provisions are now in the SDPWS,
to which the NDS refers. None of the provisions taken directly from the NDS
have changed for this edition.
2. References to the Design Standard Editions
The
references to design standards have been updated in the following places:
a) Welcome, About Shearwalls, and Building Codes
Dialog
The new
design standards implemented are listed in the Welcome dialog box that appears on program start-up, and can be
invoked later via the Help menu, and
in the About Shearwalls box from the Help
menu. More detailed information is given in the Building Codes dialog box invoked from the Welcome box.
In the Building Codes dialog, the reference to
the NDS clause that references the SDPWS has changed from Chapter 14 to
1.1.1.4.
b) Log file
The log
file, which gives the equations used for wind and seismic load generation and
for torsional analysis, has been updated for the new design code references.
The
header to the log file now says that it implements IBC 2015 and SDPWS 2012, as
well as the existing ASCE 7-10 references.
c) On-line Help
The On-line
Help documentation has been updated to refer to the current design code
editions.
3. References to the Design Standard Clauses
Where
necessary, references to design code clause numbers in program messages, notes,
table legends, etc., have been updated, as follows.
a) SDPWS
In
general, clauses were added to the SDPWS but the existing provisions kept their
original numbering. There were no instances of changes to SDPWS clause numbers
in the program.
b) NDS
References
to clauses from Chapter 10 of the NDS were incremented to Chapter 11, and
Chapter 11 to Chapter 12. References in
Shearwalls to 10.3.6 for fastener slippage were changed to 11.3.6, and nail
withdrawal capacity 11.2-3 was changed to 12.2-3.
c) On-line Help
The few
design code clause references that have changed have not yet been updated as within
the On-line Help as of the date of the software release. The Help is now
accessed over the Web, and will have the updated references by Feb 2017.
The WoodWorks package no longer installs a .pdf files for the On-line NDS and On-line SDPWS on your computer. The Help menu links and Start menu icons now direct you to websites where viewable versions of the NDS, the NDS Supplement, and the SDPWS are accessed.
Note that the NDS Commentary is no longer included.
In the Building Codes dialog box that is accessed from the Welcome box:
A note has bee added saying that nail withdrawal and hold-down bolt elongation procedures are taken directly from the NDS design standard.
The reference to the removal of the 1997 UBC design code has itself been removed
This section deals with the engineering provisions and calculations only; how they are reflected in program operation, drawings, and output reports is described in later sections.
In what follows, the symbol b is the segment length between openings/wall ends and h is the wall height as shown in the wall input view, that is, not including the height of the floor joist.
1. Aspect Ratio Factors and Adjustments
As per SDPWS 2015 4.3.3.4.1, the Aspect Ratio factors and adjustments (currently called H/W factors in Shearwalls) now depend on the choice of shearwall rigidity method in the Design Settings.
As before, these factors are applied over a range of aspect ratios of 2:1 to 3.5:1 for wood structural panels (WSP) and 1:1 to 3.5:1 for fiberboard. However, the WSP factors are now applied to both wind and seismic design, whereas formerly only the fiberboard factors applied to both.
a) Capacity-based rigidity
When Shearwall capacity (wood panels and fiberboard only) is chosen, the program applies an aspect ratio “adjustment” of 2b/h for WSP and 0.1 + 0.9 b/h for fiberboard, for both wind and seismic design.
Note that these are the aspect ratio factors for seismic design from SDPWS 2008. The changes for 2015 for capacity-based design involve a change in the fiberboard adjustment for wind design to what was previously the seismic factor, and the application of the WSP adjustment to wind design when the factor was previously only for seismic.
b) Deflection-based rigidity
When Deflection of wall segments or perforated walls is chosen, the program applies an aspect ratio factor of 1.25 - 0.125 h//b for WSP and 1.09 - 0.09 h/b for fiberboard, for both wind and seismic design
The factor for WSP is new and now applies to both wind and seismic, not just seismic as before. The factor for fiberboard is the previous factor for wind design, now applied to both wind and seismic.
c) Perforated Walls
The aspect ratio factor from SDPWS 4.2.4.2 is no longer be applied to perforated walls, as per SDPWS 4.3.4.3. This factor for perforated walls is now always 1.0. The new “adjustments” for capacity-based force distribution from 4.3.3.4.1 are not applied either.
Instead, the length of the wall used to calculate the perforated wall factor Co is shortened for narrow segments as described in the following section. This results in a greatly reduced penalty for narrow segments for perforated walls.
2. Aspect Ratio Length Adjustment for Perforated Walls
In determining the sum of segment lengths ∑Li as defined in SDPWS 4.3.3.5 the program now multiplies any segment lengths Li with aspect ratios between 2 and 3.5 by 2b/h, as per SDPWS 4.3.4.3. This applies to walls of any sheathing material type.
The calculation of ∑Li is modified in this manner for the following purposes:
a) Perforated Wall Factor Co
The calculation of Co using SDPWS Table 4.3.3.5 and using Equations 4.3-5 and 4.3-6, which are newly implemented in Shearwalls.
b) Hold-down Forces T and C
The calculation of Perforated Wall tension and compression hold-down forces T and C using SDPWS Eq’n. 4.3-8 in 4.3.6.1.2.
c) In Plane Anchorage Shear Force vmax
The calculation of the in-lane force transmitted to collectors, vmax using SDPWS Eqn. 4.3-9. In 4.3.4.6.1.1. vmax is shown in the Shear Results table.
d) Anchorage Uplift Force t
The anchorage uplift force t based in vmax in SDPWS 4.3.6.4.2.1. This force appears in Elevation View.
e) Deflection of Perforated Walls.
The deflection of perforated walls using SDPWS 4.3.2.1, both in the use of vmax and in the calculation of segment length b, which is taken as ∑Li.
3. Same Materials and Construction on a Shearline
The SDPWS Commentary C4.3.3.4 clarifies what is meant by “same materials and construction” along a shearline to mean that classes of materials such as wood structural panels, gypsum wallboard, fiberboard must be the same, but details such as the sheathing thickness and nailing patterns do not have to be identical.
Shearwalls previously imposed a stringent interpretation of this rule, applying all the inputs in the Wall Input form to every wall on a shearline. The program now allows dissimilar materials to the extent of the new Commentary, and as further clarified in discussions with AWC.
This new interpretation necessitated changes in the input of walls and in the output of results that are described elsewhere; this section pertains to engineering design implications.
a) Design Setting
A Design Setting has been added to allow you to continue to use the old method that forced identical material specifications on a shearline, or to allow the same type of material but different details.
Shearwalls are considered as having the same material and construction if they are all sheathed with the same materials from the following broad classes
- Gypsum-based (GWB, Gypsum sheathing, Plaster and lath)
- Wood structural panels (Structural sheathing, Structural 1, Plywood siding)
- Lumber sheathing
- Fiberboard
c) Combination of Sheathing Materials
According to AWC, the intent of this clarification is that all walls on a line must be composed of the same composition of material classes, e.g. wood on one side and gypsum on the other, except that it is possible to have no material on one of the sides and still be considered the same composition.
The case of alternating sides, e.g. wood/gypsum on one wall and gypsum/ wood on another wall, is not allowed in Shearwalls even though it is permissible in the AWC interpretation of the SDPWS. It has been restricted in Shearwalls for simplicity and due to the rarity of its occurrence in real structures.
d) Separate Wall Design
Previously, the program ran the design routine that determines the choices for unknown materials just once for each shearline. Now, if you choose to allow different material details for each wall in a line, the program runs the design separately for each wall. Note that this can result in increased processing time and impractical designs with slightly different details on adjacent walls. This can be mitigated by defining Wall Groups which force the same wall design.
e) Iterative Design for Capacity-based Distribution
Previously, only deflection-based design used iterative design based on the distribution of forces within a line, that is, redesigning shearwalls after forces are redistributed to shearwall segments based on the previous design. For capacity-based distribution with identical materials on each wall, shear distribution per unit foot to the segments did not change based on new designs.
Now that different material details are allowed on each wall in a line, the force distribution can change, and the program now performs iterative wall design to stabilize the distribution of shearline forces on the wall. The program runs down the line and designs the walls, then distributes forces and designs again. The process is repeated until succeeding iterations result in the same wall designs on each wall, or until 5 iterations are made.
Note that the deflection-based routine does only 2 iterations. The capacity-based distribution method iterates more times because
- It doesn’t have the processing overhead of the deflection procedure, which must first iterate numerous times to equalize deflections
- Distribution based directly on wall capacity is likely to be more sensitive to wall design changes than that based on stiffness, which is only partially due to wall materials, but affected more by geometry and hold-down elongation.
4. Sheathing Combination Rules
The clarification in the SDPWS Commentary C4.3.3.4 regarding what is meant by “same materials and construction” along a shearline inspired a re-evaluation of the definition of similar vs. dissimilar materials on opposite sides of the wall. The following changes were made after consultation with AWC as to the intent of the SDPWS 4.3.3.3 and its subsections.
a) Combination of Identical Materials
The program will continue to add the sheathing capacities of opposite sides of the wall as per 4.3.3.3 only if walls are identical in every material respect, In the case of wind design, they are also added when using the Exception for combinations of structural panels or fiberboard and gypsum given in 4.3.3.3.2.
b) Combination of Similar Materials
For materials of the material same class (i.e. wood structural panels, gypsum-based, fiberboard, etc.; see 3.b) above), but where any material property such as nail spacing or sheathing thickness is different, the sheathing combination rule given in SDPWS 4.3.3.3.1 is used. It involves apportioning the shear strength in relation to the relative apparent stiffnesses Ga of either side of the wall.
This method had not been employed previously in Shearwalls because the program used only the 4-term deflection equation, which does not include Ga, and because prior to the clarification in the SDPWS and by AWC as to the definition of dissimilar materials and construction, it was unclear how this method applied to our Shearwalls model.
i. Blocking Factor
Although the SDPWS indicates that nominal (that is, unfactored) shear capacities are to be used, for sheathing nailed to blocking on both sides of the wall, including the blocking factor in the calculation of both Ga and vs is equivalent to applying the blocking factor after the sheathing combination is done.
For sheathing nailed to blocking on just one side, there seems no other way to incorporate the blocking other than to use Ga1, vs1, etc. factored by the blocking factor. So, the blocking factor is applied to all Ga’s and vs’s when performing this calculation. Note that it is rare to nail sheathing to blocking on only one side.
ii. Aspect Ratio Factor
Shearwalls applies sheathing combination rules to materials after the aspect ratio factor has been applied, whereas the SDPWS procedure uses unfactored vs. Since both sides have the same material type thus the same aspect ratio factor, applying the aspect ratio to vs1 and vs2 is equivalent to applying it to the resulting vs, and the Shearwalls methodology is equivalent to the SDPWS procedure.
iii. Wind Design
Although 4.3.3.3.1 specifies that this procedure is for seismic forces only, it is also done in Shearwalls or wind, as per recommendations from AWC.
5. Perforated Shearwall Calculation Method
Via a new Design Setting, the program now allows you to choose between the formulae in SDPWS 4.3-5 and 4.3-6, and Table 4.3.3.5 in determining the Co factor that is applied to the capacity of perforated shearwalls. Previously, the program implemented only the table.
The program actually implements an equation that was used to generate Table 4.3.3.5. This equation is
Co = 1 /( 3h0/h - 3h0/h *
∑Li / Ltot + ∑Li / Ltot )
where ho is the maximum opening height and the other variables are as defined in the SDPWS. Equations 4.3-5 and 4.3-6 are
Co = r Ltot /(3-2r)∑Li ; r = 1 / (1 + Ao / h∑Li)
Where Ao is the total opening area. These equations are evidently quite different and yield different results. Either method is acceptable.
There is no provision in the program to allow for situations where there is no sheathing above or below the opening that is included in the definition of Ao. If you encounter this situation, just enter larger opening sizes.
6. Hold-down Database Update (Feature 202)
The hold-down database has been updated to include the most commonly used hold-downs from the most recent Simpson’s product catalog.
a) Species Categories for Hold-down Capacity (Feature 181)
The hold-down database now has separate capacities for
the categories of species of the studs that the hold-downs are attached to. These
species groups are Douglas Fir-Larch / Southern Pine (DF/SP) and Spruce-Pine-Fir / Hemlock-Fir (SPF/HF).
i. Determination of Species Category
The program identifies the species group to be used by the specific gravity of the stud material. For Specific Gravity less than or equal to .49 the program uses SPF/HF values, and above 0.49 it uses DF/SP values.
ii. Materials Below Minimum Threshold
The Simpson data do not apply to materials with a specific gravity less than 0.42. For visually graded lumber, the S-P-F (S) species, and for MSR/MEL, the Western Woods and Western Cedars species and the Engelmann Spruce/ Lodgepole Pine grades with E less than 1.5 all have specific gravities less than 0.42.
If one of these materials is used, the program applies the SPF/HF hold-down capacities, and issues a warning note under the Hold-down Design table.
iii. Materials Above the Maximum Threshold
General Note f of the Simpson Wood Construction Connectors 2015-2016 catalog says “the species of lumber used shall have a specific gravity not greater than 0.55 as determined in accordance with the NDS.” No visually graded lumber species have a S.G. greater than .55, but for MSR and MEL Doug Fir-L (N) grades with E of 2.3 or greater and Southern Pine grades with an E of 1.8 or greater have specific gravity greater than 0.55. Shearwalls allows these materials without giving you any warning, so it is recommended that they not be selected for shearwall design.
iv. Hold-down Database Editor
A new column has been added in the Design properties list (formerly Displacement) for DF/SP capacities, and the existing column has been renamed to indicate SPF/HF.
b) ASD Deflections
The hold-down database now has separate deflection values for Allowable Stress (ASD) and Strength design. Previously it had only strength-level deflections. ASD deflection values are now used for deflections from wind loads to distribute forces to the shear segments in the main wind force resisting system (MWFRS) for shearwall design.
Strength-level deflections are still used for seismic design, and for the newly added serviceability wind loads used for story drift limit calculations.
i. Hold-down Database Editor
A new column has been added in the Design properties list (formerly Displacement) for ASD deflections, and the existing column has been renamed to indicate Strength.
c) Existing Projects
The hold-down names are all different than the ones in the previous database, so none of the standard hold-downs in existing project files are in the new database. When Shearwalls opens your old project files, and detects a hold-down that is not in the database, it will add that hold-down to the new database.
i. Species Category and ASD Deflection Values
Since the old database did not have different capacities based on species group, and did not have ASD deflections, the program assigns the old SPF/HF capacity value to DF/SP as well, and the old strength-level deflection to ASD deflection. So, after loading a project file from previous versions, we recommend you open the hold-down database editor and revise the DF/SP capacities and ASD deflection values to the correct ones from the Simpson product catalog.
ii. Custom Hold-downs
It is possible that you have already edited the old database to include at least some of the hold-downs in the new database. However, the names you would have used are likely to be slightly different than the standard names, so these hold-downs will be duplicated when you load your project files. You can use the hold-down database editor to remove the duplicate hold-downs, making sure that the names of the remaining hold-downs match the ones in your project files.
7. Out-of-plane Sheathing Capacity
Some of the out-of-plane wind load capacities for C&C design of sheathing from SDPWS Table 3.2.1 have changed:
- 3/8” sheathing, parallel, 24” spacing: 25 to 30 psf
- 7/16” sheathing, parallel, 24” spacing: 30 to 35 psf
- 15/32” sheathing, parallel, 24” spacing: 40 to 45 psf
- 19/32” sheathing, parallel, 24” spacing: 65 to 75 psf
- 23/32” sheathing, perpendicular, 16” spacing: 805 to 840 psf
- 23/32” sheathing, perpendicular, 24” spacing: 360 to 395 psf
- 23/32” sheathing, parallel, 16” spacing: 215 to 255 psf
- 23/32” sheathing, parallel, 24” spacing: 95 to 115 psf
8. Bug Fixes and Small Improvements
a) Critical Segment Determination for Deflection-based Distribution (Bug 3191)
For deflection-based design, the program determined the critical shearwall segment for design via the largest unit (plf) force on the segment, without r egard to aspect ratio. It then applied the critical aspect ratio factor to that force, however the aspect ratio could be from one segment and the force from another.
Because narrow segments tend to deflect less and draw less force than wide ones, it happens frequently that the critical force comes from the wide segment and the critical aspect ratio from the small one.
The now determines the critical segment by dividing the force by the aspect ratio and taking the largest of these values.
b) Shear force on Segments for Capacity based Distribution (Bug 3189)
For capacity based distribution within a line, the design shear force for each segment on a wall was based on the segment with the critical aspect ratio, so that an entire wall has the same shear unit (plf) shear force, rather than assigning different forces to each segment based on the factored capacity of each segment.
This had a conservative affect on shearwall design. Although the critical segment for design (the one with the highest aspect ratio) was using the correct capacity, it was drawing too much load because too little was apportioned to the non-critical segments.
This also had an affect on the force distribution for story drift deflections, however how it affected the maximum deflection on the line depends on other factors and it could be conservative or non-conservative.
It also affected hold-down forces. Those at the ends of the segments with non-critical aspect ratios were too lightly loaded, and the others too heavily loaded.
These problems have been corrected.
c) Perforated Shearwall Factor for Hold-downs
The program was not applying the perforated shearwall factor Co to the hold-down force T determination in Eqn. 4.3-8 in SDPWS 4.3.6.1.2. This has been corrected.
d) Persistence of "Design as Group" Checkbox in Standard Wall Mode (Bug 3022)
When you unchecked the Design as Group checkbox in Standard Wall mode, the change was not retained when selecting another standard wall or exiting the box, making it impossible to specify that standard walls are not designed as a group. This has been corrected.
e) Aspect Ratio Factor for Perforated Walls (Bug 3178)
An example was presented to us in which the program did not apply SDPWS 4.3.4.1 stating that the height-to width factor of 2b/s be applied to the entire perforated wall based on the narrowest segment in the wall.
In this example, the narrowest segment is 3 feet in an eight-foot height wall, leading to a factor of .75. This factor does not appear in the shear results table, and the, and the 200 plf wall strength reduced only by the .61 Co factor, yielding 123 lbs, when it should also have been reduced by the aspect ratio factor for a strength of 91 lbs.
This behaviour could not be replicated for other examples, and whatever may have caused this instance was corrected by the fact that aspect ratio factors are no longer applied directly to perforated walls for SDPWS 2015.
f) Failure to Apply Aspect Ratio (Bug 3180)
An example was presented to us in which the program did not apply the aspect ratio factor 2bs/h from SDPWS Table 4.3.4 Note 1. For a 3-foot wide segment in an 8-foot wall, which should have a factor of .75, no factor was shown in the shear results table and the design capacity was not reduced; it was 200 plf rather than the expected 150.
This behaviour could not be replicated for other examples, and this instance was corrected by the extensive changes to the implementation of aspect ratio factors for SDPWS 2015.
g) Force Distribution due to Unsorted Openings (Bug 2099)
Occasionally, after a complex set of user interface operations, wall openings could become unsorted internally and skew the distribution of forces on the shearline, also affecting shearwall design. This has been corrected.
h) Dead Load Contribution to Hold-down Forces for Rigid-Only Design (Bug 3153)
Hold-down forces components due to dead loads were not created when designing for rigid diaphragm forces only, that is, when flexible diaphragm analysis is turned off in the Structure view. These force components did not appear in the Hold-down Design table or in Elevation View, and the deflection analysis and design of hold-downs did not include the counteracting effect of dead loads. This has been corrected
i) Vertical Accumulation of Hold-down Forces from Different All-heights Load Cases (Bug 3105)
When the critical shearline force acting on different levels came from different all-heights load cases (Case 1, Case 2, or Minimum), the hold-down forces were not accumulating vertically.
This created two smaller hold-down forces on the levels which were drawn on top of each other in Elevation view, instead of a single hold-down force with the combined value.
These smaller hold-down forces also appeared in the hold-down results table, and the hold-down device was verified against each of these smaller forces rather than the larger combined force. One of the hold-down forces, selected at random, was used for deflection design, creating a lower deflection than if the full hold-down force was used.
These problems have been corrected.
j) Roof Height Used for Approximate Period Calculation (Bug 3199)
The program was using the eave height to calculate the approximate period Ta in ASCE 7-10 Equation 12.8-7); however according to the definition of hn in 11.3 Symbols, the mean roof height should be used.
This error does not affect the seismic base shear calculations unless the calculation for Csmax (ASCE 7-10 equations 12.8-3 and 12.8-4) governs.
Note that the definition for hn changed between the ASCE 7-05 and ASCE 7-10 editions, and the program was not updated for the change. It has now been corrected.
k) Manually Input Loads Entered after Case 2 Wind Loads (Bug 3181)
A manually input load of any type entered after a Case 2 wind load would not be detected by the load distribution system and not contribute to design or appear in the load and force drawings.
This has been corrected.
l) Shear Capacity in Elevation View (QA Bug 42)
The capacity shown in Elevation View under the shearwalls for All shearwalls was including the average of the aspect ratio factors for all segments on the wall, which is both confusing and lacking in design significance. It now shows the unfactored capacity. The factored capacity is shown for the Critical Segment below.
m) C&C Sheathing Capacity in Elevation View Table (QA Bug 42)
The C&C sheathing capacity shown in Elevation View under the shearwalls was mistakenly including the aspect ratio factor, which is intended for in-plane shear design and does not apply to out-of-plane C&C design. This has been corrected.
3153
n) OSB and GWB in Wet Service Conditions (Bug 3000)
Oriented strand board (OSB) and gypsum wallboard (GWB) are no longer allowed for wet service conditions. When you try to add one of these materials to a structure for which wet service conditions is set, the program disallows the entry. If such materials exist in the structure, the program disallows entry of in-service moisture content greater than 19%.
o) Drag strut Forces on Perforated Walls with Zero Length Segments (Bug 2982)
Perforated walls which contain a wall segment with zero length were showing nonsensical values for drag struts that are located after the zero-length segment. Zero length segments occur when an opening is placed at the very beginning or very end of a wall.
1. Story Drift Limitations for Wind Loads (Feature 223)
The program now implements the story drift limitations from ASCE 7-10 Commentary Appendix C Serviceability Considerations, CC.1.2 Drift of Walls and Frames (page 580).
a) Drift Limits
ASCE 7 CC.1.2 suggests limits in the range of 1/600 to 1/400 of the storey height. A design setting has been added to allow you to enter the drift limit to be imposed.
The storey height h used is the wall height plus the joist depth on the same level.
b) Wind Speed
The wind speed to be used is from the maps in Figures CC1 to CC4 of ASCE 7-10, corresponding to mean recurrence intervals (MRI) of 10, 25, 50, and 100 years, respectively. It is up to the designer’s judgement as to which of these to choose.
i. Input
A new data group has been added to the Site Dialog called
Wind speed, which includes the input MRI (serviceability) to allow you to enter
the value for your area from these maps. The existing input for shearwall
design has been renamed Basic (MWFRS).
The default for new files is 100 mph.
Unlike the design wind speed, the program does not
currently allow you to save a value as default for new files; it must be reset
for every project.
c) Load Combination
The load combination employed is D + 0.5L + Wa, from ASCE 7 CC.1.2.
This combination is used for serviceability calculations only, i.e., for the in-plane shearwall deflection to be compared to drift limits. It is not used for the deflections used to distribute loads for shearwall design; these now use the ASD load combination from 2.4.1, 0.6W + 0.6D. (Previously strength-level load combination was used, see item 3 below for a description of that change).
i. Wind Load Wa
The wind load Wa is derived from the serviceability wind speeds using the same provisions that are used to generate wind loads for shearwall design from ASCE 7 Chapters 26-28. The only difference is the wind velocity used to create pressures in 27.3.2 and 28.3.2.
In determining deflections, Wa is used for:
- the segment force v, including v used to calculate overturning hold-down force
- the wind uplift component of the hold-down force
- the overturning component of hold-down forces transferred from upper stories.
ii. Dead Load D
The dead load factor is 1.0, as opposed to the 0.6 ASD factor for MWFRS deflections used for force distribution for shearwall design. These factors are for dead loads counteracting the wind overturning hold-down force
iii. Live Load L
The 0.5L component is not considered, as the program does not include live loads. In any event, it is not clear that these loads are permitted as counteracting loads or are intended only to increase deflections, as one cannot depend on the occupancy load to be present.
d) Shearline Forces
The program does not create a separate load case to determine shearline forces for drift-limit deflection; instead, it uses the ASD shearline forces multiplied by a factor α representing the difference in wind pressures between those used for serviceability and for MWFRS design, as well as the difference in load combination factors. Since wind pressures are given in ASCE 7 27.3.2 and 28.3.2 by P = d * Kz * Kd * Kzt * V2 * G * Cp, in which all terms except for V are the same, this factor is
α = PSERV / PMWFRS / 0.6 = (VSERV / VMWFRS)2 / 0.6
i. Rigid Diaphragm method.
The assumption that shearline forces are proportional to wind pressures is not strictly true for the rigid diaphragm method due to nonlinearity in the torsional distribution to shearlines. However, for typical asymmetric buildings with a significant torsional component, the difference in shearline forces using this approximation compared with generating and distributing reduced wind loads Wa is less than 1%.
ii. Comparison with ASD Forces
The program makes a separate set of defection calculations for ASD design of shearwalls, to distribute shearline forces to the shear resisting elements. Unlike serviceability deflections, the wind speeds used to generate the force for these deflections depend on Risk category; however, they do not depend on a discretionary selection of recurrence interval (MRI).
Using the southern tip of Florida as an example, the factored forces resulting from serviceability wind speeds and load combination range from 34% of the ASD forces for Risk Category III/IV buildings at 10-year MRI to 130% of ASD forces for Risk Category I at 100 year MRI. For a typical case of Risk Level II (Normal) at 50-year MRI, serviceability forces are 87% of ASD forces.
iii. Distribution to Segments within Line
The process of distributing forces to segments in a line such that they equalize deflections is performed independently for serviceability wind forces. Because some of the deflection components are constant with respect to v, one cannot rely on the distribution of forces achieved with the MWFRS wind speed and just factor each segment force by α, as we do with shearline forces. If capacity-based distribution to segments is used, it is possible to do so.
e) Calculation of Ga for the 3-term Deflection Equation
As the program now gives you the option of using the 3-term deflection equation from SDPWS 4.3-1 (see item 2 below), a question arises as to what apparent shear stiffness Ga to use for serviceability wind loads. The SDPWS publishes Ga values for seismic design only, and does not offer guidance on wind loads.
We have implemented a procedure for serviceability wind loads that is analogous to the procedure for seismic loads using the SDPWS Equation C4.2.2-3. Instead of using 1.4 vs,, we use α vw where α is defined in the previous subsection. This procedure applies to wood structural panels only; for other materials, we use unfactored vw, which results in a Ga close to what is published in the SDPWS for seismic design. The formula for Ga is therefore
Although this procedure was developed by WoodWorks it has been approved by AWC.
i. Background and Rationale
The Ga value is calculated for seismic design using is a linear approximation of the 4-term equation arrived at by combining the multiplicands of v in the 3rd and 4th terms into an “apparent” shear stiffness.
The linearization is achieved by setting all non-linear instances of the shear force v in Ga to the value at shearwall capacity, vs. This means that the 3-term and 4-term equations are the same at full shearwall capacity, and ensures that the linear 3-term deflections are conservative with respect to the non-linear 4 term ones for all shearwalls that have sufficient capacity to resist the applied shear force. Refer to SDPWS figure C4.3.2 for a graph of this linearization process.
For seismic design an adjustment is necessary, because
deflections are calculated using v’s for Strength-level design, with a load
combination factor of 1.0, however the shearwall capacity vs is for
ASD design, which has a factor of 0.7. Therefore, to ensure that the 3-term
approximation is conservative for all shearwalls that pass ASD design, the
value 1.4 vs is used. (For historical reasons, SDPWS rounds the
factor to 1.4 rather than using 1 / 0.7, which converts ASD forces to
strength-level forces).
For serviceability wind loads, the v’s used for deflection calculations are the
ASD design forces multiplied by α, which includes the serviceability wind speeds and the serviceability
load combination factor. Therefore, the serviceability v at the point at which
the shearwall is fully loaded is α
vw.
ii. Comparison with Published Ga
Some users may not be comfortable with using Ga values other than those published in the SDPWS for seismic design, especially since they are the same Ga values used, by coincidence, for MWFRS wind design with wood structural panels. Although Ga is published in SDPWS as a physical parameter, it is not a physical property of the sheathing in the same sense as Gvt, which is used in the 4-term equation; it is also an artifact of the linearization procedure used to convert 4-term to 3 term, in that it is highly dependent on the point chosen to intersect the 3-term and 4 term equation.
If the published Ga were to be used, in most
cases it would cause the 3-term to intersect the 4-term at a point far above
the point at which shearwalls are fully loaded. As an example, for a shearwall
that is 80% loaded, for 10 year MRI this causes shear/slip deflections for the
3-term equation to be 2-3 times higher than they would be using the α
factor. For a typical case
of 50 year MRI, Normal risk level, the deflections are 28% higher. This would
be problematic as designers often have difficulty meeting stringent drift
limitations.
For 100 year MRI, the equations intersect below the point that the shearwall is fully loaded, so that the 3-term deflections would be non-conservative with respect to 4-term by as much as 40%.
iii. Non-structural-wood-panels
For fiberboard and gypsum wallboard, the nail slippage in the 4-term equation is constant, and the 4-term equation is not in fact non-linear. The effect of Ga the 3-term equation is to vary the shear component deflection from 0 to the deflection at shearwall capacity, rather starting at the constant shear nail slip value. The arguments in the previous sections therefore do not apply, and we were instructed by AWC to use the published Ga values for seismic design for these materials.
f) Hold-down Displacement
When calculating hold-down displacements, the strength-level values from the hold-down database are used, as the wind load combination factor 1.0 is the same as it is for strength-level design. Note that ASD values are now used for MWFRS deflections.
g) Output
i. Design Results
Refer to section N below for changes to the Design Results output arising from this feature.
ii. Log File
Because serviceability shearline forces were derived from ASD forces, as described above, serviceability wind loads were not generated and do not appear in the log file. Torsional analysis for serviceability wind loads is not performed independently and does not appear either.
h) Plan View
Because serviceability shearline forces were derived from ASD forces, as described above, serviceability wind loads were not generated and do not appear in the Plan view when Generate Loads or Loads and Forces is selected. Neither is there an option at present to show the forces derived from serviceability wind loads in Loads and Forces view.
2. 3-term vs. 4-term Deflection Equation (Feature 211)
Shearwalls now offers the choice of using the linear 3-term deflection equation from SDPWS 4.2-1 and the non-linear 4-term equation from C4.3.2-1. Previously only the 4-term equation was implemented.
a) Background
The 3-term equation is a linearization of the 4-term
equation, arrived at by combining the shear and nail slip equations in the
4-term equation using an “apparent” shear stiffness Ga. The linearization is achieved by setting the
non-linear occurrences of shear force v to the shear capacity of the shearwall to
render them constant. It is therefore
identical to the 4-term equation when the shearwall is at capacity,
conservative when below capacity, and non-conservative for shearwalls that are
overstressed for design anyway. SDPWS Figure C4.3.2 shows this in graphical
form.
The four-term equation was originally implemented in Shearwalls because it is more accurate and because the SDPWS does not publish Ga values for wind design. However, the process of equalizing deflections on the shearwall segments by adjusting the forces apportioned to each segment sometimes does not converge due to the non-linearity of the 4-term equation, whereas the 3-term equation always converges to a solution. Also, some users are more comfortable using the 3-term equation because it is in the main body of the SDPWS, whereas the 4-term equation is in the Commentary.
b) Design Setting
A Design Setting has been added to allow you to choose between these two methods. It is recommended to use the 4-term equation, but switch to the 3-term if using the deflection-based force distribution method and one or more of the shearlines do not show the same deflections on each loaded shearwall segment in the line.
Note that SDPWS commentary C4.3.2 cautions against mixing the two methods in the same design, as it can adversely influence force distribution based on relative stiffness. This is true within a line, and possibly distribution to shearlines if the rigid distribution method is used. For a future version we will consider allowing the program to automatically change from 4-term to 3-term on individual shearlines if non-convergence is detected, especially using flexible distribution; however, for Version 11, the switch must be made manually and for all shearlines in the structure.
c) Wind Design
The SDPWS lists Ga values for seismic design only, and gives design examples using the 3-term equation and showing how to calculate Ga for only for seismic design. However, Shearwalls allows this method for wind design, with the adjustments to the calculation procedure given below.
d) Deflection Calculation
The following terms in the two-term equation
are replaced by
i. Ga Calculation, Seismic
The calculation of Ga for seismic design uses the formula
The factor 1.4 ≈ 1/0.7 ensures that the v
is evaluated at the maximum allowable shear
for ASD design, given that the v value in the deflection equation is calculated
using strength design. (1.4 is used rather than 1/ 0.7 for historical reasons.)
In most cases, the value of Ga is the same as that listed in Table 4.2B, but it may be slightly different because the use of the equation allows us to consider the number of plywood plies when evaluating Gvtv., whereas note 3 of Table 4.2B approximates this effect by applying a factor of 1.2.
ii. Ga Calculation, MWFRS Wind
For wind deflections for MWFRS force distribution, the same expression is used without the 1.4 factor, because we now evaluate deflections with ASD forces and there is no need to convert from ASD design to Strength deflections. The formula for Ga is
For wood structural panels and fiberboard, this results in the same Ga values as for seismic design because the shearwall capacity vw = 1.4 vs. It is important to note that this is merely a coincidence; the difference in capacity for wind vs. seismic is for unrelated reasons pertaining to a historical increase in design wind loads related to test strengths. The increase was not applied to other materials such as gypsum wallboard, and these have different Ga values for wind vs. seismic design.
iii. Ga Calculation, Serviceability Wind
Shearwalls 11 includes a new set of serviceability deflections for story drift determination, described in the preceding section, which also includes the calculation of Ga for serviceability wind forces.
iv. Unblocked Factor
The unblocked factor Cub is applied only to the v value in the main deflection equation. not the vs and vw values in the calculation of Ga. This is consistent with SDPWS Eqn. C4.3.2.2-2, where it is shown that dividing v by Cub is equivalent to factoring the whole shear stiffness Ga by Cub.
v. Capacity Increase for 3/8” and 7/16” Sheathing on Unblocked Shearwalls
As per Commentary C4.3.2.2, the capacity Increase for 3/8” and 7/16” sheathing under certain framing conditions from Table 4.2A Note 2, is not applied to vs or vw for unblocked shearwalls for the purpose calculating Ga.
e) Output
Refer to N.8 below for changes to the Deflection table arising from this feature.
3. ASD Deflections for MWFRS Wind Loads
On the advice of AWC, Shearwalls now calculates deflections to distribute forces to the main wind force resisting system for shearwall design based on the ASD load combination 0.6D + 0.6W from ASCE 7-10 2.4. Previously Strength-level deflections were used, using 0.9D + 1.0W, from ASCE 7-10 2.3, because they are required for seismic design by 12.8.6 and the ASCE 7 does not offer guidance on wind design.
a) Force Calculation Changes
The wind load factor changes from 1.0 to 0.6 for the shearline force v, for wind uplift hold-down force, and for the effect of hold-down forces from upper levels.
The dead load factor changes from 0.9 to 0.6 for the counteracting dead load component of hold-down force.
b) Hold-down Database
Previously the hold-down database had only strength-level deflections. It has been expanded to include ASD deflections to be used for ASD wind design. Strength-level deflections are retained for seismic design and for serviceability wind loads for story drift calculations.
4. Fiberboard Deflection Factor
To implement the new SDPWS provision 4.3.2.3, if there is fiberboard on either side of a wall segment with an aspect ratio greater than 1:1, the total deflection for the segment is multiplied by (h/b) ½.
If there is any fiberboard in the structure, the application of this factor is mentioned in the Legend to the Deflection table, however the actual value of the factor is not listed in the table.
5. Bug Fixes and Small Improvements
a) Shearwall Capacity Hold-down Method in the
Calculation of Deflections (Bug 2999)
If you specify via the Design Settings that shearwall capacity is to be used as the design force for hold-down design, this value was also used to determine the hold-down component of shearwall deflection. As this is not the intent of the use of shearwall capacity to ensure sufficient hold-down strength, the calculation for deflection now always uses applied force to determine hold-down displacement, regardless of the design setting for hold-down forces.
b) Tolerance in Equalizing Deflections (Change 227)
Occasionally, warnings appeared indicating the program had not equalized deflections on the shearline, when the Design Results output showed identical deflections along the line. This was because the tolerance for equalizing deflections internally was 0.01% of the deflection value, which is unnecessarily stringent. It has been changed to .5%”, which ensures that when deflections are not equalized to that level, it is apparent in the output table.
c) Deflection Equalization Failure (QA Bug 18)
Occasionally, for two-sided shearwalls, the program would show v, vmax, and Critical response values in the Shear results table as dashes or blanks, even though there is a total force V on the wall in question.
This was due to an intermittent failure in the process equalizing deflections on either side of the wall, and has been corrected.
Extensive changes to several of the Design Settings was necessitated by the following changes to the SDPWS:
the Aspect Ratio Factors in SDPWS 2015 4.3.4 and adjustments in 4.3.3.4.1 are now identical for wind and seismic design, whereas in SDPWS 2008 Table 4.3.4 the factors applied only to seismic design for wood structural panels, and differed between seismic and wind for fiberboard.
For capacity-based force distribution, gypsum-based materials or lumber sheathing are no longer allowed, as per SDPWS 2015 4.3.3.4.1, and for wood structural panels and fiberboard, an “adjustment” is applied to narrow segments, rather than the Aspect Ratio factors in 4.3.4 that apply to deflection-based distribution.
The SDPWS now recognizes only capacity-based and deflection based force distribution methods.
The SPDWS C4.3.3.4 clarification of the definition of “similar materials and construction” along a shearline
The changes to the design settings also, present the options more understandably, use the current SDPWS terminology, implement SDPWS provisions that were previously omitted, and simplify special cases such as the treatment of fiberboard.
1. Shearwall Rigidity Settings
a) Data Group Name
The data group previously called Shearwall rigidity per
unit length… is now called Rigidity for shear force
distribution based on…
It is no longer necessary to state that it is “per unit length” because of the removal of the Equal rigidity and Manual rigidity discussed below.
b) Capacity-based distribution
The setting Use shearwall capacity to approximate rigidity is now called Shearwall capacity (wood panels and fiberboard only). If selected, it causes the new Ignore non-wood panel contribution setting for Walls entirely sheathed with gypsum-based materials or lumber sheathing to be checked and disabled, so that these materials do not contribute to force distribution, design or deflection calculations, as per SDPWS 4.3.3.4.1.
c) Deflection-based distribution
The setting Use
shearwall deflection to calculate rigidity has been renamed Deflection of wall segments or perforated walls. This indicates more precisely what
the method entails than the use of the word “shearwalls”.
d) Shearwalls have equal rigidity
This option has been removed because as it is not allowed by the SDPWS and has no physical justification.
e) Manual Rigidity
This option has also been removed for the following reasons:
It was originally in the program to allow you to enter a rigidity based on deflection calculations that the program did not do at the time, but now does.
There is no way of judging whether this rigidity is based on capacity or deflection, so no way of deciding which of the aspect ratio factors (SDPWS 4.3.4) or adjustments (4.3.3.4.1) to apply.
Note that some users had been using this input to model proprietary non-wood shear resisting elements, however that was not its original intention and we plan to implement a more rigorously designed implementation of proprietary elements in the near feature.
f) Distribute forces to wall segments based on rigidity
This setting has been removed, as it’s purpose was to use deflection-based or capacity-based distribution of externally applied load to shearlines, but to distribute forces to segments equally within the shearline. Since the Equal rigidities option has been removed because it is not allowed by SDPWS, this option has been removed by the same reasoning.
g) Files from Previous Versions
If Equal rigidities or Manual rigidities was active in a project file from a previous version of Shearwalls, or Distribute forces to wall segments based on rigidity was not selected, the program changes the distribution method to your default method, and the program issues a message after the file is loaded explaining the reason.
Unless you have changed it to capacity-based, the default distribution method is deflection-based.
2. Ignore Non-wood-panel Contribution
a) Data Group Reorganization
The data group previously labelled Ignore non-wood panel contribution… offered a grid of settings based on wind vs seismic on one axis, and whether it was for all walls or only when combined with wood structural panels on the other axis.
The group is now labelled Ignore contribution of…, then provides three checkboxes as follows:
b) Gypsum-based materials and lumber sheathing when combined with blocked wood structural panels or fiberboard in walls with narrow segments
Checking this setting has the same effect as checking both the corresponding settings for wind and seismic design in Version 10, that is, it causes the program to neglect GWB, plasterboard and other gypsum based materials and lumber sheathing in design, deflection calculations, and capacity-based force distribution when there are blocked structural wood panels or fiberboard on the other side of the wall.
It is no longer disabled and checked when the All gypsum based materials for seismic design setting is checked, as the corresponding seismic setting was when For all walls/ Seismic was selected. The operation of these inputs is now independent, because the new setting applies to both seismic and wind design.
It is disabled and unchecked when Allow 3.5:1 aspect ratio is unchecked, as was the corresponding seismic setting in Version 10 (the wind setting did not do this).
i. Application to Walls with Narrow Segments Only (Bug 2037)
The words walls with narrow segments were added to describe a new condition that was added to improve this feature. For the non-wood-panels to be disregarded, the wall or shearline must contain at least one segment that has an aspect ratio less than 3.5:1 but greater than 2:1 for structural wood panels and 1:1 for fiberboard. This way, the program is not disregarding shear-resisting materials throughout the structure just because it is required for a few short shearwalls.
This change was required also to maintain the usefulness of this setting, because it previously existed primarily to allow you to ignore these materials for seismic but not for wind, which is no longer necessary.
c) All gypsum-based materials, fiberboard and lumber sheathing for seismic design
This operates the same way as the previous All walls setting under Seismic, that is, all non-structural-wood panels will be neglected for design, deflection calculations, and capacity-based force distribution when the setting is checked.
Previously, checking this caused the setting for walls combined with wood panels to be disabled and checked for seismic. This no longer happens, because the corresponding setting now applies to both wind and seismic.
Because of this, it is now possible to have this setting checked and the setting for ignoring these materials when combined with wood structural panels unchecked. In this case, the restriction that all these materials are ignored takes precedence and the program disregards the setting pertaining to when they are combined with wood structural panels.
d) Walls entirely sheathed with gypsum-based materials or lumber sheathing
You cannot set this setting, it is always disabled, and is automatically checked when the Rigidity for shear force distribution setting is set to Shearwall capacity. Its purpose is to inform you of that the restriction based on SDPWS 4.3.3.4.1 is in effect, that is, that only wood structural panels and panels are allowed unless the force distribution is based on deflection analysis.
When this checkbox is checked, any wall that has either gypsum or lumber sheathing on both sides, or those materials on one side and nothing on the other side, is entirely neglected for design, deflection calculations, and capacity-based force distribution.
e) Including Fiberboard
The informational text including fiberboard has been removed, as it is now explained in the checkbox text.
f) Files from Previous Versions
If a file is opened from a previous version that had All walls / Seismic checked, then the corresponding checkbox is checked for wind design.
If a file had either of the settings for wind or seismic, when combined with structural wood panels checked, then the corresponding setting for both materials is checked.
The setting for Walls entirely sheathed with gypsum … is checked based on whether capacity-based distribution or deflection-based distribution is checked when the file is opened.
This setting allows you to avoid aspect ratio penalties by excluding the contribution of shearwall segments with ratios between 3.5:1 and 2:1 (WSP) or 1.1 (fiberboard). Previously, the wood structural panel option applied only to seismic design.
a) Data Group Name
The data group title for this has changed from Seismic wood panels, and fiberboard to Wood structural panels and fiberboard.
b) Setting Name
The name has changed to Allow 3.5:1 aspect ratio to reflect current SDPWS terminology.
c) Interaction with Other Inputs
Unchecking this causes the setting under Ignore non-wood… called Gypsum-based materials … when combined with wood… to be disabled and unchecked, as it currently is for the corresponding checkbox for seismic design in Version 10.
d) Effect on Design
This setting is applied to wind design in the identical manner that it previously was for seismic design only, that is, if it is checked, any segment between less than 3.5:1 but greater than 2:1 for structural wood panels and 1:1 for fiberboard is not considered a full height segment and is not apportioned any force for design.
4. Disregard Shearwall Height-to-Width Limitations
This setting was in the program to allow you to include proprietary shear resisting elements that are not subject to aspect ratio limitations for wood shearwalls. Since the ability to enter rigidities for these elements was removed as described above, this input would have no function other than to circumvent limitations mandated by the SDPWS. Accordingly, it has been removed until we implement a rigorous treatment of proprietary elements in future version.
5. All Shearwalls on Shearlines have Identical Materials
The SDPWS Commentary C4.3.3.4 clarifies what is meant by “same materials and construction” along a shearline to mean that classes of materials such as wood structural panels, gypsum wallboard, fiberboard must be the same, but details such as the sheathing thickness and nailing patterns do not have to be identical. However, the current operation of the program forcing these materials to be identical has advantages in terms of processing time and generating practical designs. For this reason, a Design Setting has been added allowing you to force the use of identical materials along a shearline.
The checkbox for this setting reads All shearwalls on a shearline have identical
materials and construction.
The default value is unchecked, that is, non-identical materials along a line are allowed (but the program still forces all materials to be of the same material class, as described in M.1 below.
When files from previous versions are opened, the capability is de-activated, because the previous designs did not allow this. However, a message appears informing you of the ability to change the setting and allow non-identical materials along a line.
6. 3-term vs 4-term Deflection Equation (Feature 211)
A setting has been added to allow you to choose between the 3-term deflection equation from SDPWS 4.2-1 and the 4-term equation from C4.3.2-1. Previously only the 4-term equation was included. The implementation of the 3-term equation is described in section I.2).
The default option is 3-term, because that is the option in the main body of the SDPWS rather than the Commentary, however, for more accurate deflections, 4-term is recommended.
Existing files from older versions use the 4-term equation, so that the designs do not change.
7. Perforated Shearwall Co Factor Calculation (Feature 171)
A setting Perforated shearwall Co factor calculation has been added to allow you to choose between the formulae in SDPWS 4.3-5 and 4.3-6, and Table 4.3.3.5 in determining the Co factor that is applied to the capacity of perforated shearwalls. Previously, the program implemented only Table 4.3.3.5.
By default, the program uses the equation, however files from previous versions will continue to use the table when first opened.
8. Story Drift Limit for Wind Loads (Feature 223)
Shearwalls now includes a Storey drift table for wind design (see I.1 above). A design setting has been added to allow you to set the story drift limit as a proportion of shearwall height. The default value is 1/ 500 which is midway in the suggested range of limits of 400 to 600 by ASCE CC.1.2. You can change this using Save as default for new files.
9. Moisture Condition Category (Change 218)
Adjacent to the input of Moisture Content in the Design Settings, the program now indicates whether the value is considered dry or wet by the NDS. This is now also indicated in the Design Results echo of the Design Settings.
Numerous improvements have been made to the Elevation View drawing. Refer to the B:Engineering Design section for physical explanations and design code references pertaining to the information presented.
1. Zoom and View Settings (Feature 216)
You are now able to zoom Elevation View in and out and to establish view settings similarly to Plan View.
a) Elevation View Setting Tab
A tab for Elevation
View has been added to the Settings box, with similar inputs to the View tab for Plan view. The setting
previously called View has been
changed to Plan View.
i. View Area
You can establish the confines of your viewing area with the View area inputs, or change them using the Zoom buttons in the Elevation View data bar.
ii. Fit Building to Viewing Area and Fit Viewing Area to Window
These settings act similarly to Plan View, allowing you to recapture the full image of the structure after it has been zoomed.
iii. Plan View Snap Increment
Since there is no interactive input in Elevation View, the snap increment entered in the Plan View settings is shown here, and is used as the metric for the Display gridlines input.
iv. Display Gridlines
You can now display gridlines at a different interval from how they are shown in Plan view using this input.
v. Zoom Increment
You can set the percentage by which the image expands or contracts each time the Zoom in and Zoom out buttons in the Elevation View data bar are pressed.
b) Toolbar Buttons.
Zoom in and Zoom
out buttons in the Elevation View data bar expand or contract the image by
a percentage increment entered in the Elevation
View settings.
c) Mouse Wheel
It is also possible to zoom the image via the mouse wheel, owing to the new feature described in L.4 below.
2. Segments, Aspect Ratios and Aspect Ratio Factors (Feature 77)
a) Display Setting
In the Show menu and in the Display data group of the Options settings, you can now turn on and off the display of segment numbers, and aspect ratio information, separately.
b) Segmented Shearwalls
i. Segment Number
In the upper portion of shearwall segment, centered horizontally, the program shows the segment number after the wall number, e.g. A-1,1; A-1, 2; etc.
ii. Aspect Ratio
Under the segment number is the aspect ratio of the segment, shown as A.R. followed by the value.
iii. Aspect Ratio Factor
For those segments that have an Aspect Ratio factor or
adjustment other than 1.0 (i.e. segments with aspect ratios greater than 2.0
for wood panels and 1.0 for fiberboard), under the aspect ratio it shows the
factor or adjustment. For deflection-based force distribution the factor is
preceded by Fact; for capacity-based
distribution it is preceded by Adj.
iv. Critical Segment
Within the design results text below the drawing, the program now gives the critical segment, e.g. A-4,2, in which 4 is the wall number and 2 is the segment number. Previously it just indicated the segment was within wall A-4.
c) Perforated Shearwalls
i. Segment Number
For perforated shearwalls, segment numbers are not shown, because they do not correspond to segments shown in the Design Results output and they are not used independently in force analysis or design.
ii. Aspect Ratio
The aspect ratio for perforated wall segments is shown as it is for segmented walls, as it is used to factor the shearwall length used in calculating the Co factor.
iii. Segment Length Li
For all segments, including non-FHS segments, the segment length Li, possibly factored by aspect ratio factors adjustments, is shown, in feet.
For non-FHS segments, the value of Li is 0.00.
iv. Sum of Segment Lengths and Total Wall Length
The sum of factored segment lengths ∑Li and the total wall length Ltot used in the calculation of the perforated wall factor in SDPWS Eqn. 4.3-5 now appear after the perforated wall factor Co under each perforated wall.
The word “Perforated” has been removed as it is now evident from all the data specific to perforated walls.
3. Dimension Lines (Feature 79)
Dimension lines indicating the length of full-height segments or of perforated walls, opening length and height, joist depth and wall height are now shown in Elevation View.
In both the Show menu for Elevation View, and in the Display data group of the Options settings there is a checkbox to turn off the display of dimensions for walls and for openings independently. Joist thickness is also turned off when walls are turned off.
b) Location of Dimension Lines
i. Full Height Segments and Perforated Walls.
Full height segments in all segmented shearwalls and entire perforated walls or non-shearwalls are dimensioned in the bottom area of the wall.
ii. Openings
The horizontal dimension of openings is shown on top of the opening if there is room, otherwise within the opening.
The vertical dimension of openings is shown inside the opening on the right-hand side.
iii. Wall Height and Joist Thickness
The wall height is dimensioned to the left of the entire shearline, and the joist thickness to the right.
c) Format
Dimensions are in feet, and you can control whether feet-inch or fractional feet, and whether fractional inches are shown, using the Imperial Format setting for Distance.
4. Shading of Non-shear-resisting Segments (Feature 56)
The following elements are now shaded in light gray to indicate that they are not considered shear resisting elements.
a) Segmented Walls
Within segmented walls, segments which are too narrow to be considered full-height segments, and are this not included in design and do not draw force, are shaded.
Openings are shaded above and below the opening
b) Perforated Walls
For perforated walls, only non-full-height segments at the ends of the walls before any full-height segment is encountered are shaded.
Non-full-height segments that have full height segments both before and after them anywhere in the wall are not be shaded because the length Ltot includes such segments.
c) Non-shearwalls
Non-shearwalls are shaded except for the openings.
5. Display of Roof Line and Gable End (Feature 228)
In the Show menu while
in Elevation view and the Display data
group of the Options Settings in the Elevation view column, items have been
added for the display Gable end and for
Roof.
When Roof is checked, the gable end is always shown and its checkbox is disabled and checked.
i. Gable End
This setting controls the display of the triangular gable end of the wall. If the setting Ceiling acts as upper level diaphragm is checked in Structure view, this portion of the wall is not considered part of the shearwall, and turning off the setting economises on space without compromising the depiction of forces on the line.
ii. Roof
This setting controls the display of side panels and hip ends, which do not affect the distribution of forces within the shearline, so this setting can be turned off to economize on space if only the forces within shearwalls are of interest
b) Gable Ends
Gable ends are part of the end wall, and it was previously unclear whether they were considered part of the shearwall, as they are if Ceiling acts as upper level diaphragm is unchecked in Structure view,
i. Wall drawing
If selected for display, gable ends are drawn in the same green colour as the wall.
ii. Force arrows
When Ceiling acts as upper level diaphragm is unchecked in Structure view the program draws the arrows for the diaphragm shear force and the segment shear forces along the slope of the gable end rather than at the level of the top of the upper storey.
These force locations are used in the calculation of the moment arm for hold-down force calculations, however previously that was not apparent.
If you choose not to draw gable ends, then the forces are drawn along the top of the upper level wall at eave height, even though they act at the height of the sloping roof.
c) Hip Roof and Side Panels
Hip roof panels and side panels are drawn in a mid-gray colour, and the entire outline of the panel is drawn, including the line at eave height.
The panels are drawn only if the roof block edge is collinear with the wall, in other words, if the roof is made of rafters, the wall supports the rafters.
Roof panels are drawn only for those blocks whose highest level corresponds to one of the levels selected in Elevation view.
6. Multi-storey Selected Walls (Feature 230)
You can now choose to view Selected Walls while viewing multiple levels or multiple levels while in Selected Walls mode. In this case, the program shows only walls that are above and below the selected walls. This allows you to view see the entire vertical load path for a single stack of walls. Previously, it was difficult to do so for long shearlines because the data tended to overlap.
a) Data Bar Controls
Previously, when Selected Walls was chosen in Elevation view, the levels control was disabled. Now it is enabled.
b) Drawing
When in Selected Walls mode while more than one level is being viewed, the program uses the walls on the level selected in Plan view to determine what walls are shown on other levels. It shows all walls on other levels that are entirely within the extents of the selected walls.
If contiguous selected walls are selected, the program shows walls on other levels within the total extent of the contiguous walls, even if they do not lie within the extent of any one of the selected walls. However, if there is a gap between selected walls, the program does not show walls on other levels that lie even partially within that gap.
If you find this difficult to envision, just experiment with the program.
7. Bug Fixes and Small Improvements
a) Display of Total Shearline Force (Bug 3104)
The total shearline force that usually appears at the top of the first wall on the line in Elevation view did not appear if it was less than the shearline force for the opposite direction from that which is being shown. This has been corrected.
b) Anchorage Shear Force t
In the Elevation View drawing of the Anchorage Shear force t for perforated walls from SDPWS 4.3.6.4.2.1, the arrows are now drawn so they do not obscure the shear force and anchorage force values, and the anchorage force has been raised so that it does not overlap the shear force.
c) Placement of Segment Shear Force Values (Feature 79)
For multi-storey structures, the numeric value of the shear force on each segment has been raised above the arrows for the design shear force on the storey above, if they would otherwise be obscured by them or by the diaphragm itself.
d) Crash for Offset walls with Dead Loads (Bug 3138)
For shearwalls offset from the shearline location, and if dead loads were on the wall, the program was crashing when Elevation View was viewed. This ha been corrected.
e) Selected Walls from Multiple Shearlines (Bug 3167)
When individual walls from different shearlines were selected in Plan view, Elevation view in the Selected Wall mode showed all these walls, even if they overlap. Now the program shows only the walls from the first shearline selected, as it does when multiple entire shearlines are selected when in Entire Shearline mode.
f) Disabled Level Input in Elevation View (Bug 3172)
After re-entering the Structure action or Roof action in Plan View are selected, then going to Elevation View, the Level input was disabled and you were unable to change the levels being viewed. This has been corrected.
g) Drawing of Offset Walls (Bug 3175)
When walls on a shearline are offset in plan from neighbouring walls, in Elevation view the offset walls were drawn slightly than normal, causing a small gap between walls. This occurred consistently when viewing one level and occasionally when viewing multiple levels, and has been corrected.
h) Rescaling after Disabling Material Information (Bug 3177)
After disabling the framing, nailing, or sheathing information under the shearwalls in Elevation view, it did not rescale to accommodate the change in information. This resulted in you being unable to see the information when it was re-enabled, or the view having a large amount of blank space along the bottom when the information was disabled. These problems have been corrected.
i) Shear force in Elevation View for Narrow Segments (Bug 3190)
Occasionally, when the segment aspect ratio was between 2 and 3.5 so that an aspect ratio factor is applied, no design force was shown in elevation view for that segment. The aspect ratio factor was applied to the design shearwall force as shown in the Shear Results table, so this was a graphical display problem only. It has been corrected.
j) Hold-down Force Deactivation in Show Menu (QA Bug 75)
After running a design, it was not possible to turn off all hold-down forces via the Show menu, just to choose between combined and separate hold-downs. This has been corrected.
k) Show Menu Groups (Change 224)
Added a separator to the Elevation View Show menu separating the options dealing with graphical elements such as wall names with those dealing with design results text.
1. Wall Depiction in Plan View
a) Non-full-height Segments
All shearlines with aspect ratios that are too narrow for design given the selected Design Settings are now shown with a white interior and coloured border the same as a non-shearwall, as they are effectively non-shearwall segments
b) Aspect Factor Segments
All segments which require an Aspect Ratio factor or adjustment given the current settings are now shown with a diagonal hash mark. This distinguishes them from perforated walls, which are double-diagonal.
c) Legend
A legend below at the bottom of the screen shows the markings for Segmented walls, Perforated walls, Non-shearwalls, and Aspect factor segments.
2. Centre of Mass and Center of Rigidity (Feature
218)
The
program now shows the location of the center of loads and the center of
rigidity of the structure, for both wind and seismic loading. These appear in Loads and Forces action when Rigid diaphragm forces are chosen for
display. Two small dots with the symbols CL and CR appear.
You
can turn on and off the display of these points using the Show menu.
The
perpendicular distance between these points in each direction is the moment arm
used for torsional analysis for rigid diaphragm distribution.
3. Design Case in Plan View (Feature 83)
The program now indicates explicitly Plan View whether you are viewing seismic or wind loads, which wind load method and case, and the force distribution method (rigid or flexible diaphragm). Previously you had to infer this information from the arrow style, existence of large low-rise arrows, and other clues.
a) Loads and Forces View
In the line in the legend previously starting with Loads shown [W, Qe]: it now shows, with the square brackets indicating separate scenarios:
Loads: [ Seismic (Qe), [ Directional Case [ 1,2 ] , Envelope, Minimum ] Wind (W), ] … [ ; Rigid, Flexible ] distribution ]
Within the ellipsis in the above, the program gives load combinations and seismic force modification equations as it previously did.
b) Loads Generate View
Where it previously said Unfactored generated shear load, the program now says
Unfactored generated [ wind, seismic ] shear load [ using [ Directional method Case [ 1, 2 ], Envelope method, Minimum loads ] ]
The program now zooms the drawings of the structure via the mouse wheel. Previously this could only be done via toolbar buttons.
In Plan View and for the new zoom feature for Elevation view, when the Control key is depressed, each click on the mouse wheel expands or contracts the image by percentage increment given in the View settings, like one push on the zoom button.
5. Bug Fixes and Small Improvements
a) Zoom Buttons in Fit Building to View Area Mode (Bug 3170)
In Plan View, when Fit Building to Viewing Area is active, the zoom buttons on the toolbar were disabled, because the building no longer fits the viewing area when zoomed.
However, this view option is the default, so it was often unclear why the zoom buttons were disabled. For this reason, the zoom buttons now remain enabled, and their use deactivates the Fit Building to Viewing Area setting.
This behaviour is also adopted for the new feature of zooming and Fit Building… for Elevation view.
b) Legend Wording for Failed Walls (Change 177)
The line in the plan view legend explaining the red color for failed walls now indicates that it is a “Capacity” failure, to clarify that other types of failures that can occur are not highlighted
G. Input and Program Operation
1. Dissimilar Materials along Shearline
As described in H.3 above, The SDPWS Commentary C4.3.3.4 clarifies what is meant by “same materials and construction” along a shearline such that the material specification does not have to be identical, just that the same class of materials (wood structural panels, fiberboard, gypsum-based materials or lumber sheathing) is employed.
A Design Setting has been added to allow you to force identical material specifications on a shearline, or to allow the same type of material but different details.
a) Version 10 Behaviour
In version 10, when you change any of the inputs in the Sheathing, Fastener, or Framing data groups, except for the number of end studs, the program applies the change to all wall on the line. This functionality is retained in Version 11 if the Identical materials design setting is turned on.
b) Non-identical Materials
If the Identical materials setting is not turned on, then all inputs except for the Sheathing Material change independently for each wall or wall design group on the line.
The Sheathing Material changes independently for different walls on the line only in the following circumstances:
- If it is changed from a material to another in the same class of materials, such as Structural 1 to Structural sheathing or Gypsum wallboard to Gypsum sheathing
- If it is changed from a material to None, provided that there is a material on the other side of the wall.
- If it is changed from None to a material in the same class as those that are on other walls on the line, on that side of the wall
If none of these conditions are met, when you change the Sheathing Material all walls on the line change to have the new material.
c) Dependent Materials
If the you change a Sheathing Material such that all walls on the shearline have the same material class, then for other walls than the one selected, the program changes not just the Sheathing Material, but repopulates all the Sheathing inputs that are dependent on it – thickness, plies, OSB grade, nail type, nail spacing.
d) Wall Groups
If you change any of the materials in a wall group, then all walls in that group wherever they are in the building, change to have the new materials.
If all walls must have identical materials, then all shearwalls on a line must have the same wall group. If there are walls on other lines with that wall group, then the whole shearlines they are on must also have that wall group, and change en masse to having the new materials for that wall group.
However, if all materials except for the Sheathing Material can be different on a shearline, then if you change the Sheathing Material, all walls on the line must have the new material, even if they are of different wall groups. All walls on other lines of the same group or groups also must change the Sheathing material, to maintain identical group properties. Then all other walls on those lines must change the Sheathing Material to maintain the same material on the line, and so on. This process propagates in a tree-like fashion throughout the structure.
To give an example, suppose that Line 1 has Groups 1 and 2, with GWB materials. Line 2 has Groups 3 and 4 with WSP, and line 3 has Groups 2 and 4 as well. If you change a wall in Line 1, Group 1 to Fiberboard, then Group 2, being on the same line, will have Fiberboard as well. But Group 2 is on line 3, so Group 4, which is also on that line, changes to Fiberboard as well. But Group 4 is also on line 2, so Group 3, which is on that line, changes to Fiberboard. All groups wind up having Fiberboard.
2. Link to Wind Velocity Web Site (Feature 213)
In the Building Site dialog, there is now a link to the website http://windspeed.atcouncil.org/ that provides maps and address lookups to find the design wind speeds for your area for each risk category. This website also provides 10-, 25-, 50- and 100-year mean recurrence interval wind speeds for serviceability wind loads, to be used for story drift calculations.
A similar link exists for seismic ground accelerations.
3. Log File in Viewer (Feature 208)
The log file which provides load generation and rigid diaphragm analysis details has now been integrated into the program and appears in a window within the program framework. Previously the program invoked the Notepad program to show the log file results. The window is called Load Generation and Torsional Analysis Details. The menu and status bar descriptors have also been updated.
4. “Getting Started” Steps Display (Change 181)
The list of steps helping you to get started using the Shearwalls program has been placed in a scrollable view, and formatted with bold titles for each step. The number of steps had become too large to fit on the screen without a scroll bar.
a) Web Help
The On-line Help is no longer accessed from a file installed on your computer; it is now accessed via the Web. The Help will now be updated with corrections and for changes to the program as they occur.
b) Update for Version 11 Changes
The On-line Help has not yet been updated for the changes for version 11 described in this document. The Help will have the updated descriptions by Feb, 2017.
c) USA-specific Help
The Help is now specific to the USA version of the program. References to Canadian design procedures and program operation have been removed.
6. Bug Fixes and Small Improvements
a) Invalid Keycode Message (QA Change 23)
The message that appears saying your keycode is invalid now directs you the WoodWorks Sales email address.
b) Product Code in Software ID (Feature 13)
The three-digit code in the software ID that identifies the software version has been expended to 5 digits.
c) Information in About Shearwalls box
In the About Shearwalls box accessed from the Help menu:
Misplaced colons and brackets in the design code and standard sections have been removed.
In the sales and tech support sections, email communication has been emphasized over phoning, phone extensions were added, the fax number was removed, and the website is now a link to the site rather than text.
The words WoodWorks Technical Support were mistakenly removed, and have been put back.
d) Network Installation Error (Bug 3151)
Occasionally, when running the software from the network installation the program would fail, giving the following error message: "When running from a server, the initialization files must be in the 'Common Application Data' folder, refer to the documentation for information network installation."
This problem has been corrected.
e) Add Load Dialog Input (Bug
3005)
The following corrections have been made to the Add a New Load dialogue box:
i. Wind C&C Loads
When Wind C&C is selected,
-
The Apply to... input was limited to Building face but the list was filled
with wall lines. The Apply to input
now shows Wall lines
-
The magnitude labels From and To changed to Interior and End but failed to consistently update back to From and To when a
different type was selected.
ii. Apply to Selected Walls
When Apply to…
Selected Walls was selected, the From
and To location did not update
properly so that the load would not be applied to just the extent of the
selected wall.
iii. Dead Loads on Building Face
You can no longer apply dead load and building mass loads to an entire building face. These loads are more appropriate to a wall line
iv. Element for Wall Line Loads
For wind shear and seismic loads the Element was always shown to be Face even when applied to a wall line. It now shows the wall line it was added to.
f) C&C Wind Loads in Both Directions (Change 176)
When adding a new C&C load, it is now possible to select "Both ways" for wind direction, as the program now distinguishes between suction C&C loads for both nail withdrawal and sheathing strength, and bearing wind loads which impact sheathing strength only.
g) Width of Load List (Bug 3077).
The list of input loads has been widened to show
the Profile column without scrolling.
h) Extend Upwards Operation (Bug 3073)
In extending upwards in stages, the program created an extra level on the level above the one you selected to extend to, and uses the original block outline to create that level instead of the modified footprint. You could then only extend from that level upwards. For example, extending to level 2 on a 4-storey structure, the program copied the modified footprint to level 2 and added the original footprint to level 3, and placed you on level 3. If you extend to a level below the top, the extra level was placed on the topmost level and the process was complete.
This extra level is no longer added when extending levels in stages, for example if you extend to level 2, the program merely copies the modified ground floor level to level 2 and places you there to proceed.
i) Crash on Input of Standard Walls (Bug 3202)
After restoring all Standard Walls to the ones that originally came with the program using the Default Values setting, the program crashed if there were any standard walls that you had made being used in the project.
Shearwalls now only allows the standard walls to be reset if there are no open documents. If you attempt to reset them with a document open, the program now prompts you to close the open document.
j) Wall Segment in Wall Input View
The data group identifying the Wall segment has been changed to Wall, because the data correspond to an wall with openings and possibly several full height segments. The program now outputs shear design results and dimensions for each segment along a wall, so the definition of a wall segment in Wall Input view would conflict with the definition in the Design Results.
k) Default Seismic Redundancy Factor ρ (QA Change 14)
The default value for the seismic redundancy factor ρ in the Site Information box is now Calculated, indicating that the program determines this factor on the first design and does a second iteration to re-generate loads. Previously the default value was 1.0, in which case it is up to the designer to detect if the resulting design does not actually change it if the resulting design does not actually have a ρ of 1.0 and change it.
l) Update of Roof Overhang Input (Change 186)
In the roof input form, the roof overhang values were being set to zero when switching from a flat roof to a sloped roof and back again. They are now restored to their previous values.
m) Settings Input Dialog for Medium and Large Display Size (Bug 3068)
It was sometimes not possible to view the all the Settings input tabs when medium or large Display Size was selected in Windows. It could happen that you were unable to click the buttons at the bottom that close the boxes.
These boxes have now been reorganized in a shape like that of a typical computer screen, so that the entire box fits in the view regardless of the display option selected.
n) Apply Button in Settings Dialog (Change 185)
The Apply button has been removed from the Settings dialog because it had no effect.
o) Typo in Out-of-date Design Message Box (Change 178)
The repeated word “design” has been removed from the message box that appears telling you that your structure has changed and your previous design is out of date.
p) Image File Wording in Message (Change 182)
In a message saying that the CAD file had not been imported, the words Windows metafile have been changed to image file, as several types of images are now imported.
q) View Setting Nomenclature
The following changes have been made to the data field labels in the View settings, which area now shown in separate Plan View and Elevation View boxes:
i. Mouse Click Interval (Change 225)
The word intervals has
been changed to snap increments for
consistency with the nomenclature in Display
Gridlines, which uses the term snap
increment. For Display gridlines, Snap has been changed to snap.
ii. Save to Project File (Change 226)
An asterisk (*) has been placed beside those inputs that are not saved to the project file, with an explanatory note at the bottom of the box. These inputs are the zoom increment and the Fit Building… and Fit Window… settings
r) Hold-down Database Editor
In the dialog box that allows you to create new hold-downs,
i. Displacement / Elongation Dialog Title
The title table that allows you to enter hold-down data capacities and displacements has been changed from Displacement or Elongation to Design properties, in recognition that it is not just deflection data that are entered, but design capacities as well.
ii. Design Properties Table Width
The table now called Design Properties has been widened to allow the headings to be fully visible.
s) Spelling of Story in Settings (Change 228)
In the Options and Hold-down settings, the word story is now used instead of the
Canadian/British storey.
t) Preview Mode in Design Results Viewer (QA Bug 18a)
Sometimes the Site Information table, and perhaps others, spilled outside the confines of the page when in Preview mode. This has been corrected.
If they are not indicated below, refer to Engineering Design, Design Settings, or Deflection Analysis sections of this document for physical explanations and design code references pertaining to the changes to the information presented in the Design Results.
a) New Settings
The following new settings are presented in the Design Settings table:
- Wind story drift limits
- SDPWS deflection equation (3-term vs 4 term)
- Non-identical materials on shearline allowed
- Perforated wall factor Co calculation method
b) Removed Settings
The following setting has been removed from the program, so it no longer appears in this table:
- Design shearwall force/length
c) Other Changes
i. Moisture Conditions
The words Dry or Wet are placed after the moisture condition percentages.
ii. Relative Rigidity Formatting
For consistency with other cells containing phrases rather than numeric data, Shearwall relative rigidity is now in sentence case rather than title case.
The new input for serviceability wind speed for story drift calculations is shown in the Site information table.
a) Canadian Design Code Reference (QA Bug 46)
A message regarding story drift referred to the Canadian NBC design code reference. This has been changed to ASCE12.12 for seismic design and ASCE 7 CC1.2 for the new wind provisions.
4. Shearline, Wall and Opening Dimensions Table
a) Segment Dimensions
For walls with openings, the dimensions of the segments between openings now appear, in sequence with the openings at each end of the segments.
i. Perforated Walls
The length of segments within perforated walls is the value of Li defined as in SDPWS 4.3.4.3, that is, factored for the aspect ratio of narrowed segments.
b) Full Height Sheathing
Regarding the columns showing the full-height sheathing length:
i. Wind vs. Seismic
Because the rules defining full-height segments are now identical for wind and seismic design, the program no longer shows two columns for wind and seismic design; only one value is now shown.
ii. Perforated Walls
The length of full height sheathing displayed for perforated walls is ∑Li as defined in SDPWS 4.3.4.5 and 4.3.6.4.1.1, that is, factored for narrow segments using 4.3.4.3. This is explained in the legend.
c) Aspect Ratio
A column has been added called Aspect Ratio, which shows the height-to-width ratio for wall segment, or walls when the entire wall is one segment.
Aspect ratios are shown for the segments in both perforated and segmented walls.
For walls and shearlines when no aspect ratio is shown, a short dash appears.
d) Legend
The legend has been modified in accordance with the new format of the table and information presented.
e) Bug Fixes and Small Improvements
i. Wall Order
Occasionally, walls would appear out of order in the table. This has been corrected.
ii. Legend Format
The legend now has consistent capitalization of leading words.
iii. Shearline Type (Change 229)
Shearlines no longer show a type, Perforated or Segmented, as there can be both on a shearline. Previously it was showing the first wall’s type.
a) Results by Segment
Due to the increased importance of Aspect Ratio Factors with SDPWS 2015, if a segmented wall has openings, the program now shows shear design results for each full height sheathing segment in the wall. For each segmented wall with openings, lines starting with Seg. 1, Seg. 2, etc. appear after the line for the entire wall. They do not appear for perforated walls.
Note that the output described below for the table rows for individual segments also occurs for table rows for walls when there is only one segment on the wall and shearlines when there is only one segment on the shearline.
i. Display Option
In the Show menu and the Options settings, a checkbox has been added to control the display of results by segments. If this is not selected, the program displays wall-by-wall results as before, except for improvements described in later sections.
ii. Force and Resistance
The force values v and V, the interior and exterior allowable shear; the combined allowable unit shear and the total shear force V are shown for each individual segment.
For unsegmented wall-by-wall output, the wall row still shows the v values for the critical segment and the V values for the or the entire wall, which admittedly can be confusing.
iii. Design Ratio
For segment by segment output, the heading Crit. Resp has been changed to Resp. Ratio
as the response ratio for each segment is shown, and you must examine them to determine the critical ratio.
For unsegmented wall design, the old heading remains and the value shown is the one for the critical segment, i.e. the one with the highest response ratio.
iv. Aspect Ratio and Unblocked Factors
The columns titled Asp/Cub (formerly H/W-Cub) shows the Aspect Ratio Factors for the segment, independently of the Unblocked factors, which will be shown in the row for the entire wall. For wall-by-wall output, the Unblocked and Aspect Ratio factors are multiplied together and cannot be discerned separately.
v. Data not Shown
The following data are not shown in the segment line, as they are the same for all segments and are shown in the row for the wall containing the segments, or they are relevant to perforated walls:
Wall group (W Gp), vmax, Perforation factor (Co), Sheathing combination (C).
vi. Zero Force
If there is zero force on the wall, the program does not show segments for that wall as there is no need to show detailed breakdown of force and resistance in each segment.
vii. Row Showing Data for Entire Wall
For segment-by-segment output when there are multiple segments in a wall, the data shown in the row for the entire wall are different from those shown in this row for unsegmented walls, as follows:
Shear force v
The value of v representing unit shear force is not shown, as it can differ for each segment.
Perforated wall values
The values of Co and vmax are not shown, as they are not applicable to segmented walls.
Allowable shear force
The interior and exterior allowable unit shear force are the ones unfactored by the Aspect Ratio factor or the Unblocked Factor Cub (In the rows for segments or for unsegmented walls, the factored capacities are shown.)
Aspect ratio and unblocked factors
The columns titled Asp/Cub show only the Unblocked factors, not the Aspect Ratio factors, for each side of the wall. The Aspect Ratio factors are shown for in the rows for shearwall segments.
Combined allowable shear
The combined allowable unit shear V is not shown, as the interior and exterior unit allowable shears are shown unfactored, and there is no design significance to adding unfactored shear capacities. The factored combined allowable shear force that is used for design can differ for each segment.
Design ratio
The design ratio is not shown as it differs from segment to segment, and it would be confusing to show some data on this line that were for the critical segment, and not others. Refer to the output for the individual segments for the critical design ratio.
b) Sheathing Combination Rules
The following pertains to the column titled “C” that indicates the rule used for combining sheathing capacities on opposite sides of the wall from SDPWS 4.3.3.3.
i. Stiffness Based Combination G
Due to changes in the interpretation of SDPWS rules to combine sheathing capacities on opposite sides of the wall, the letter G has been introduced to indicate the method in SDPWS 4.3.3.3.1 which uses apparent stiffness Ga of the walls.
ii. Strongest Side Only S
As there are no rules in the SDPWS that specify you must use the strongest side only, this option has been removed from the list of codes. The symbol S is currently shown when there is sheathing on only one side, but in reality, no rule applies in this case. A dash (-) now appears.
iii. Strongest or Twice Weakest
The program now uses use the letter S for “strongest or twice weakest”, eliminating the awkward use of the letter X for this option.
c) Non-identical Materials
Because of the clarification to the SDPWS allowing for non-identical material specification for different walls on the line, all values except for the total ASD shear force V and the total allowable shear V can no longer be assumed to be identical for all walls on the line. If non-identical materials are allowed in the Design Settings, and there is more than one wall on the line, then in the Shearline row of the table, all values except for the two instances of V are removed and replaced with a dash (-).
d) Other improvements
i. Nomenclature
Aspect Ratio Factor
The heading H/W-Cub changes to Asp/Cub, Asp standing for Aspect Ratio Factor, as per current SDPWS terminology.
Combined shear force
The heading Total changes Cmb, meaning “Combined” as Total could mean total shear force for all segments on the wall, whereas the intention is the total of the interior and exterior allowable shears for an individual segment.
ii. Reorganization
Location of Aspect Ratio/Unblocked Factor
The columns headed by Asp/Cub have been moved to precede the Int and Ext columns in
the Allowable Shear section.
Previously, it preceded the shear force values to which it was not
related.
Note that these values are included in the Int
and Ext allowable shear, just as
the Co factor is included in the
combined allowable shear column that follows it.
Relative location of shear force values
Under ASD Shear Force, the V[lbs] column has been swapped with the v column for consistency with the Allowable Shear side of the table, and to place the more common v value before vmax, which is just for perforated walls.
iii. Perforated Wall Data for Segmented Walls
For segmented walls, regardless of whether segment rows are shown, the values of Co and vmax have been changed to a dash (-), to show that they do not apply to these walls and to make the distinction between segmented and perforated walls more evident.
Previously, 1.00 appeared under Co and vmax showed the same value as v.
iv. Shearline Row
The following changes have been made to the row for the
entire shearline when there is more than one shearwall on the shearline,
otherwise the shearline row is treated as a wall row in the table..
Eliminated Data
Several data in this row were unneeded and difficult to
decipher. The following outputs repeated the output of values for the critical
wall on the line and have been removed and replaced with a dash (-): Aspect Ratio / Unblocked Factor Asp/Cub, unit shear force v, perforation factor Co,
design ratio Crit Resp.
Interior and Exterior Allowable Shear
The Int
and Ext allowable shear now shows
these values unfactored by the Aspect
Ratio and Unblocked factors. Previously it showed the factored values for the critical segment on the line. Note that the
new behavior is consistent with the output of the row for the entire wall when
wall segments are also shown.
e) Legend
Changes were made to the explanations in the legend in accordance with the revisions to the table described above, and to show updated SDPWS reference numbers and terminology also described elsewhere. In addition:
i. Collector Shear force vmax
The description for vmax refers to the collector shear force, rather than just shear force.
ii. Perforated Wall Factor Co
The description of Co has changed from Perforation factor to Adjustment factor for perforated walls or perforated wall factor.
iii. Seismic Aspect Ratio Factor
The Aspect Ratio Factor is no longer indicated to be specific to fiberboard for wind design.
iv. Combined Allowable Shear
In the explanation for combined (formerly Total) allowable shear, the unnecessary
abbreviations int. ext. and inc. have been expanded to interior,
exterior, and including.
v. Critical Design
Criterion in Response Ratio
The line explaining the meaning of the letters “W” and “S” after some response ratio values has been placed on the same line as the explanation for the response ratio, as it wasn’t clear what it pertained to.
f) Bug fixes
i. Blocking Factor for Interior Side (Bug 3188)
If no blocking is entered for the interior side of a shearwall, it shows a blocking factor of 1.00 rather than the actual factor in the shear results table. However, the design capacity shown is factored correctly
ii. Order of Wall Rows (Bug 2116)
Shearwalls were not always listed in order as they occur from west to east or south to north. This has been corrected.
iii. Total Shear Resistance V for Narrow Segments (3192)
The total shear resistance V shown in the shear results segments for a wall or shearline was the total force on all segments multiplied by the lowest aspect ratio factor, rather than the sum of the force multiplied by the aspect ratio for each segment individually. It thus understates the force on the wall.
As V is just output for your information and is not used for design, this was a display issue only. It has been corrected.
iv. Design Ratio in Shearline Row for Mixed Perforated / Non-perforated Walls (Bug 3187)
When perforated and non-perforated walls were on the same shearline, the force v shown in the shearline row was the highest force on any wall, but the allowable shear could be from a different perforated wall with a Co factor. Thus, the design ratio compared results from two different walls.
This was not a problem for non-perforated walls because for that case, all walls on the shearline had the same capacity.
It didn’t not affect shearwall design because the results that were used to design the shearwalls are shown on the shearwall row. The design ratio in the shearline row was just extra information and has been removed.
v. Design Code Reference for vmax (QA Bug 7d)
The reference to vmax in the legend was SDPWS 4.3-8 when it should be 4.3-9. This has been corrected.
a) ASD Wind Forces in Legend
The descriptions in the legend for shearline force has been modified to indicate ASD forces are now used for MWFRS wind deflections, and shows the load factors 0.6 D and 0.6 L.
b) Perforated Walls
The note for perforated walls now says that T from SDPWS 4.3-9 is used for the hold-down force, rather than saying it is factored by Co, and the note below the table has been expanded to explain the relation between T, Co and ∑Li, and where to find these values elsewhere in the output results.
c) Bug fixes
i. Order of Hold-down Output (Bug 2116)
The hold-downs were not always listed in order as they occur from west to east or south to north. This has been corrected.
a) vmax Reference in Legend
When Applied loads are selected as the Collector force method, the legend to the drag strut table now refers to vmax from SDPWS 4.3.6.4.1.1 rather than the perforation factor Co.
Co was previously referred for both Applied loads and Shearwall capacity because using vmax was equivalent to dividing by Co, but due to changes in aspect ratio calculations for perforated walls, vmax now also depends on a variable ∑Li.
b) Bug fixes
i. Order of Drag Strut Output (Bug 2116)
The drag struts were not always listed in order as they occur from west to east or south to north. This has been corrected.
a) Storey Drift Limitations for Wind Loads (Feature 223)
Separate tables are now shown for Serviceability deflections and MWFRS
deflections. A subtitle to each
table explains the use of the former for story drift and the latter for force
distribution for design.
The legend to the Serviceability table has been modified when compared to the MWFRS table to explain the serviceability wind loads Wa, the dead and wind load factors, and the factor used in the calculation of Ga for the 3-term deflection equation.
b) 3-term vs. 4-term Deflection Equation (Feature 211)
If the newly added 3-term deflection equation from SDPWS 4.2-1 is chosen, the Deflection table shows only one deflection value called Shear defl, rather than separate shear and nail slip deflection. The Ga value is also shown, and the Vn and en values for nail slip show the values at shearwall capacity vs or vw used to calculate Ga
The legend at the bottom of the table has been modified to reflect these changes.
c) ASD Wind Forces
The descriptions in the legend for shearline force v and nail force Vn have been modified to indicate ASD forces are used for MWFRS wind deflections.
d) Perforated Walls
The legend has been modified to indicate that the segment length b has been modified for aspect ratio factors, and that the shear force v used is vmax from SDPWS 4.3-9, as per 4.3.2.1.
This is not a new provision in the SDPWS, however, the definition of b and vmax now includes a variable ∑Li due to aspect ratio factors.
e) Fiberboard Deflection Factor
If there is any fiberboard in the structure, the legend indicates that, as per the new SDPWS provision 4.3.2.3, for segments with an aspect ratio greater than 1:1, the total deflection is multiplied by (h/b) ½. The value of this factor is not listed in the table.
9. Hold-down Displacement Table
a) Storey Drift Limitations for Wind Loads (Feature 223)
Separate tables are now shown for Serviceability deflections and MWFRS
hold-down displacements. A subtitle
to each table explains the use of the former for story drift and the latter for
force distribution for design.
The legend to the Serviceability table has been modified when compared to the MWFRS table to explain the serviceability wind loads Wa and load combination.
b) ASD Wind Forces
The descriptions in the legend for the uplift force P and fastener slippage Pf have been modified to indicate ASD forces are used for MWFRS wind deflections.
c) Perforated Walls
In the legend, it is now noted that for perforated walls, T from SPDWS 4. 3-8 is used for the overturning component of the uplift force P.
d) Bug Fixes and Small Improvements
Extra spaces have been removed and missing spaces between words added.
10. Story Drift Table for Wind Loads (Feature 223)
A table has been added to show the Story Drift results for wind loads. It is a simplified adaptation of the one that currently appears for seismic design, showing the wind direction, max deflection on each shearline at each level, maximum allowable deflection, and the ratio between them. A warning appears if drift limits are exceeded on any line, with an asterisk beside the line failing drift ratio.
a) Extra Null Lines in C&C Design Table (Bug 3035)
For some cases in which not all the wall design groups are standard walls, and when only one of rigid or flexible design is performed, the program output an extra row with 0 load and 0 capacity for each C&C result in the output table, and added wall design groups not related to any of the actual walls, also with 0 load and 0 capacity. These problems have been corrected
a) Nonsensical Output of Diaphragm Force (Bug 3185)
Occasionally, one of the diaphragm force Fpx values in the Seismic Information table would show a nonsensically high number. This was a rarely occurring bug due to unusual configurations of program memory, and has been corrected.
13. Load Generation Results in Log File
a) File Header (Changes 187, 179)
The following changes have been made to the log
file header block:
- the date and time now appear at the top of the file instead of each title block of the wind, seismic and torsional analysis information. The unnecessary word “Time:” has been removed.
- the header now includes the version number of the software,
- the program name, version, filename and date are separated by a blank line from the design code information below.
- The header was not appearing if was seismic only loading and thus no wind load generation section. This has been corrected
b) Main Wind Force vs. C&C Loads (Change 194)
Main Wind Force and C&C loads have been split
into separate tables for readability. Previously there were two sets of headers
for the tables and you had to correlate information for the type of load being
read with the correct header line.
c) Log File for New Project (Change 184)
Pressing log file button for a new project displayed the results from the last unsaved session. The log file button is now enabled until loads have been generated.
d) Seismic Site Information and Legend Titles and Location (Change 200, 210)
The output of Site Information for seismic load
generation has been made consistent with wind by removing the words "User
Input" and placing it first in the sequence of information reported.
The Symbols table has been renamed Legend, consistent with Wind output
e) Formatting of Subsections (Change 201)
Where a subsection of the report contains more than
one simple table, a blank line has been placed after the heading to the
subsection to indicate that all the information below it pertains to that
heading.
f) Distribution of Base Shear to Stories (Changes 206, 207,209)
The Distribution of Base Shear to Stories table often appeared in a puzzling, ragged format because an earlier format with the stories arrayed horizontally was shown along with the current format with the rows arranged vertically. This has been corrected, and the following changes have also been made:
- The story height was shown in feet and inches rather than in decimal format, which is used for all output reports.
- The name of the table has been changed to Distribution of Base Shear to Levels, to avoid the complication of differing spelling of the word storey for USA and Canada.
14. Torsional Analysis Results in Log File
a) Nonsensical Torsional Forces in Log file for
Low Rise Wind Design (Bug 3006)
After generating low-rise wind loads on a structure with a flat roof, the log file would sometimes show nonsensical output for the rigid distribution torsional forces for low-rise Case B wind loads. As this case has a net zero wind load in the direction with nonsensical output, this did not affect design. It has been corrected.
Shearwalls 10.43 – November 13, 2015 – Hot fix
This
version was sent to individual users to address bug 3022 Persistence of “Design as Group" Checkbox in Standard Wall Mode. This bug is described in the changes to Version 11, the first version released to the
general public with the fix.
Shearwalls
10.42 – October 25, 2015 – Design Office 10, Service Release 4b
Refer also to the changes for Version 10.41, below, which was distributed to only a limited number of users.
1. Seismic Mass from Interior Non-Shearwall Shearlines (Bug 3094)
The building masses created from interior shearlines composed entirely of non-shearlines were not used to create seismic loads, nor was the mass included in the calculation of total mass of the structure for base shear calculations. This has been corrected and interior non-shearwalls now contribute to seismic weight.
2. Perpendicular Direction Load Distribution from Manual Area Building Masses (Bug 3099)
Starting with version 9.2, manually input area building masses create a point seismic load in the direction defined by the start and end of the building mass, as well as the line seismic load in the perpendicular direction representing the distributed area mass in that direction.
The point load does not correspond to the actual distribution of mass and has been removed. In its place, there is a line load representing an area mass originating at the location of the building mass, and extending the tributary width that was input for the building mass. The tributary width used to create this load is the length of the input mass.
3. Story Height for Allowable Story Drift Calculations (Bug 3100)
The program was using the wall height for hsx in Table 12.2-1 to determine the allowable story drift, rather than the wall height plus the joist depth. hsx is defined as the "story" height, and the value reported in the Story Drift table and defined in the legend below includes the joist depth.
This has been corrected and the calculation of allowable storey drift includes the joist depth in the calculation of hsx.
4. Saving of Standard Walls Modified in Wall Input View (Bug 3015)
Upon exiting the program, it saved the changes made to Standard Walls that occur when changes are made to walls in the structure while "Design in Group" is checked. Therefore changes you might inadvertently make while modifying walls could affect the standard walls used for future sessions with other projects. Now, the program asks you whether you want to save the standard walls when exiting standard wall mode and when exiting the program. When exiting the program this prompt only appears if a wall has ever been modified in this way.
Previously, the program saved standard the standard wall file that is used for future sessions when saving a new standard wall, deleting a standard wall, leaving standard wall mode, or selecting a new standard wall in the drop down list in standard wall mode. It now only saves the standard walls when leaving standard wall mode and when exiting the program.
5. Both Direction Output in Storey Drift Table (Bug 3018)*
In the storey drift table, the program used to output Both to indicate, for example that the results apply to both E->W and W->E. However, this table also includes results from the other orientation, in this case N->S and S->N, so it was unclear what Both referred to. The program now says e.g. E<->W when indicating the results apply to both directions rather than Both.
Shearwalls 10.41 – October 8, 2015 – Design Office 10, Service Release
4a
This was released to only a limited number of users as the
bulk of users were not informed that it was available until service release 4b
had already been made.
1. Reporting of Height-to-Width Factor for Design Groups (Bug 3088)
In the Shear Results table of the Design Results, the program was reporting the height-to-width factor from SDPWS Table 4.3.4 Notes 1 and 3 for the strongest wall in a design group, rather than the actual wall being reported. The wall capacity and the design ratio reported were also from the strongest wall rather than the actual wall.
The impact of the bug is more severe for shearlines that are composed of a single wall than for lines with more than one wall. For single walls, the only row in the output table showing results for that shearline has the wrong h/w factor and design ratio. For shearline with multiple walls, the rows in the table for individual walls are correct, but the row at the top showing the critical case on the shearline is wrong. You can see that the individual walls make sense and ignore the shearline row.
If the strongest wall in the design group has a h/w factor of 1, this h/w factor is shown for shearlines with single walls that have h/w ratios less than 1. However, it is rare for there to be non-conservative occurrence of this bug for two reasons:
- Walls with low height to width ratios tend to be the strongest ones in the group, because the program needs to compensate for the low h/w ratio with stronger materials.
- Shearlines with just single walls on them tend to have low h/w ratios (with high factors), because one short wall will not resist the applied load.
Note that this was a reporting problem only. If the design group includes walls that have unknown values, the program applies the correct h/w factor when designing the shearwalls. It is only when reporting the results that the incorrect values appeared.
Shearwalls 10.4 – August 20, 2014 - Design Office 10, Service Release 4
1. Determination of Torsional Amplification after Redesign (Bug 2998)
After determining the torsional amplification factor Ax, the program if necessary applies the factor to the torsions and redistributes loads to the shearlines. Sometimes this triggers a redesign of the structure, and the reconfigured building may not have the same torsional amplification as before, but the program did not recalculate it. As a result, the torsional amplification shown in the output and the one calculated from the designed structure did not match.
It may even happen that the program determines that the building requires a torsional factor and then he redesigned building is no longer torsionally sensitive.
The program now applies the Ax factor calculated for the final design and redistributes loads. It does not redesign the structure again, but it shows in the output reports and in the building response to the forces from the redistributed loads. Note that this can cause a structure for which walls that were originally designed to pass now fail, or walls to be overdesigned compared to the materials needed to resist the final load distribution.
This is unavoidable because even an infinite sequence of designing, modifying the Ax, and designing again would not necessarily converge. A note at the bottom of the shear results table indicates if any walls fail this reason.
2. Design as Group for Multiple Identical Wall Groups (Bug 3026)
When design as group is activated for a standard wall that
has the same materials as another standard wall group, the program sometimes
assigned individual shearwalls to the wrong design group, that is, to a design
group for a standard wall group other than the one designated for that wall.
This has been corrected
3. Creation of Standard Wall from Wall in Structure (Bug 3025)
The Design in Group feature proved to be difficult to implement for a wall that had been created input of walls in the structure rather than via Standard Wall input, because there is no standard wall associated with the wall and design groups are accomplished through standard walls.
For this reason, the program now allows you to create standard walls from regular walls as follows:
When clicking "Edit Standard Walls" while there is a wall selected which does not match any standard wall, the program now asks you if you wish to create a standard wall based on the selected wall. If you create a standard wall in this way, the Design as Group setting is checked for the standard wall and the Design in Group checked for the selected wall.
This feature enhances the program usability in general, similar to the creation of a new font style in a word processor using the font attributes of the selected text.
4. Selection of Standard Walls that Differ Only by End Studs (Bug 2923)
When selecting a standard wall to assign to a physical wall, the number of wall studs was not being accounted for, so that if there were two standard walls that were identical except for the number of wall studs it sometimes would cause the program to assign the wrong standard wall to the selected wall. It was also not possible to select one of the standard walls in the Edit standard wall view.
Whether or not it happened depended on the order of the near-identical standard walls in the list of walls. It has been corrected.
5. Unknown Values on Interior Wall Surface (Bug 2925)
In wall input view, if you selected "Both sides the same" and specified unknown values, and then deselected Both sides the same, the unknown values were still recorded in the interior sheathing, even though design for unknowns is not done independently for interior sheathing. If these unknown values were not changed, the program would design using the weakest materials in the list, and would show question marks (?) in the Wall Design Groups output table for the interior sheathing.
Now, when you deselect Both sides the same, the program changes any unknown values on the
interior surface to the weakest possible.
Unless changed, these materials now show up in the Design Group Output.
6. Upper Level Failures in Hold-down Design Results (Bug 2948)
The Hold-down Design table of the Design Results output was reporting walls as having failed hold-down design for multiple building levels when it only failed hold-down design on the lowest level listed. This has been corrected.
7. Non-shearwall C&C Failure for Rigid-only Design (Bug 2919)
If only rigid diaphragm analysis was selected in the Structure Input view, the program showed failure for non-shearwalls in elevation view, even if the walls are strong enough to resist design. In the Components and Cladding table, the program showed a warning that these walls do not have shear resisting materials, even If they did.
This problem disappeared if you chose to do both rigid and flexible design. It has now been corrected.
8. Wind Suction Title (Change 174)
The title in the program output "Wind Suction Design" has been changed to "Out-of-plane Wind Design". This is because the governing condition can be either suction or bearing of wind.
B. Load Generation and Distribution
1. Duplicate and Missing Low Rise Wind Loads (Bug 3002)
The program would sometime take portions of low-rise wind loads generated for one corner load case and assign them to another corner load case, creating duplicate loads for one case and gaps in the other case. This was most likely to occur if the structure is heavily indented, and has been corrected.
2. Duplicate Wall Wind Shear Loads for Additional Roof Blocks (Bug 2946)
After additional blocks are created for roofs only, with no attached walls, the program was creating a duplicate set of wall wind shear loads for walls on the other blocks. For multi-storey buildings this was happening on all levels except the top level.
If the project file was saved and then re-opened and then loads were re-generated the duplicate loads were no longer being created.
This has been corrected.
3. Missing Elevation View Forces in for No Deflection Analysis (Bug 3003)
When the Design Setting was set to exclude deflection
analysis, the shear flow arrows for diaphragm shear and base shear and the
segment shear force arrows did not show up in elevation view. This has been
corrected.
4. Missing Snow Load Note in Load Generation Dialog (Bug 2988)
Under Seismic Loads in the Generate Loads dialog, the note giving the percentage of snow load used was missing. It has been restored to the program.
5. Rigidity Shown in Wall Input for Redundant Wind Directions (Bug 2913)
When the Wind directions S->N, E->W and N->S, W->E are selected in the Show menu, the Rigidity shown in Wall Input view was a nonsensical value. This was a display issue only and the correct rigidity was used in the shearwall design. It has been corrected.
1. Standard Wall Name Persistence when not Designing as Group (Bug 3026)
Sometimes, after selecting a standard wall that is not designed as a group, the standard wall name goes blank in the input field rather than showing the selected standard wall.
This happened most often when multiple walls were selected and has been corrected.
2. OSB Checkbox for Both Sides the Same (Bug 3024)
When Both sides the same was checked and the OSB checkbox checked, the OSB material was not recorded for the interior side of the wall. This has the following effects
- The program might not identify the wall as being part of a standard wall group
- The program might not include the wall in the design groups of designed walls with the same materials
- When unchecking the Both sides the same button, the OSB will not necessarily be checked on the interior surface
The design of the wall was not affected; it designed both sides of the wall with the OSB choice shown on the screen.
3. Crash After Deleting Additional Roof Block (Bug 2947)
After additional blocks are created for roofs only, with no attached walls, and wind loads were generated on these blocks, then one of these blocks is deleted, the program would sometimes crash the next time you tried to save the file, re-generate loads, or run design. This has been corrected.
4. Relative Rigidity in Wall Input View after Accept Design (Bug 2909)
After pressing the Accept Design button the relative rigidity in the Wall Input view was showing 1.0 instead of the rigidity from the accepted design wall.
This is just a display issue and the correct rigidity was used in design. It has been corrected.
5. Accept Design for Existing Files (Bug 2903)
For saved project files, the Accept Design button was defaulting to accept flexible wind design, instead of the currently selected load case and distribution method. If there were no wind loads the Accept Design button had no effect. This has been corrected.
6. Ctrl-C Operation (Bug 2964)
Previously pressing Ctrl-C caused a file close, when the standard operation that users expect is to copy selected text in an edit control, leading to significant frustration. This has been corrected and Ctrl-C now copies text and there is no shortcut for closing a project file.
7. Program Version for Saved Files (Change 173)
The program now records the version of the program used to save a project file and shows it in the About Shearwalls box when the file is opened. This feature is primarily used internally at WoodWorks for diagnostics.
Shearwalls 10.31 – October 7, 2014 - Design Office 10, Service Release
3a
1. Persistence of Manually Input Wall Rigidities (Bug 2895)
Starting with version 10.2, when manually input rigidities are selected as the rigidity method in the Design settings, the program re-set all relative rigidities to one when distributing loads.
Since load distribution is done before design, it was no longer possible to set manual rigidities that are then used in design, and the manual option was identical to the “equal rigidities” option. This has been corrected and the program again allows you to manually set the rigidity to be used for each wall in the structure.
2. Relative Rigidity as Parameter for Design as Group (Bug 2897)
If you change the manually input relative rigidity for one wall in a standard wall group, the program no longer applies it to all walls in that group, nor does it present a message box warning you of this. Instead, different walls within different groups can have different relative rigidities.
Note that the program did not apply the relative rigidity to all walls within a line walls in a line. The behaviour for design groups is now consistent with that approach. Rigidity usually depends on the geometry of the wall so it cannot be specified for all walls within a group or line containing walls of differing lengths.
The program still includes relative rigidity amongst those parameters in a Standard wall that can be used to create the initial values for a set of walls. However, it no longer includes rigidity among those parameters that define a standard wall when identifying what standard wall a physical wall pertains to.
Shearwalls 10.3 - September 23, 2014 - Design Office 10, Service Release
3
1. Design Summary (Feature 138)
To allow you to identify walls and hold-downs that fail design without having to scan the full design results report, the program now includes a design summery. It appears in the Design Results report before the shear results for the first design case (just after the loads are output). In addition, the program alerts you with a pop-up message if any walls fail.
a) Message Box for Wall Failure
If any walls
fail for any design case rigid
diaphragm, flexible diaphragm, wind shear, wind C&C, seismic), the program
shows a message box on the screen that gives the levels and he design cases that the failure occurs. It tells you to go
to the Design Results or to see the highlighted walls in Plan View (see Feature
75, above)
b) Wall Failure Summary
For each design
case (wind shear loads - rigid diaphragm, wind shear loads - flexible
diaphragm, components and cladding wind loads - out-of-plane sheathing, components
and cladding wind loads - nail withdrawal, seismic loads - flexible diaphragm, seismic
loads - rigid diaphragm) the design summary either indicates that there were no
under-capacity walls, or gives a list on each level of the names of the
shearlines with walls that failed.
c) Hold-down Failure Summary
For each design
case (wind shear loads - rigid diaphragm, wind shear loads - flexible
diaphragm, , seismic loads - flexible diaphragm, seismic loads -
rigid diaphragm) the design summary either indicates that there were no
under-capacity hold-downs, or gives a list on each level of the names of the
walls that contained under-capacity hold-downs.
d) Table Menu Item
The Go to Table menu that appears when the
Design Results are shown now includes an item for Design Summary.
2. Worst Case Design and Design for Groups when C&C Governs (Bug 2848)
In
designing for groups and for worst case design, the program considered only
shear strength when determining whether a wall should be used as the design
wall, not taking into account nail withdrawal or out-of plane sheathing
strength for C&C loading.
As a
consequence, for wind design, a wall designed for the interior of the structure
with field nail spacing that renders it too weak for out-of-plane loads could
be chosen as the design wall because it is stronger for shear than an exterior
wall that was designed for C&C loads.
.
Similarly
for worst case design, the program could choose as a wall designed for seismic
loading as the worst case wall, but it too leaves the field nail spacing at the
largest value and may fail for wind suction on the exterior surface. A wall
designed for wind on the exterior surface is was not chosen as the design wall.
because the seismic wall had a larger shear resistance.
This
was solved by tracking the worst-case design for nail withdrawal and for out-of
plane bending. If the wall chosen for shear design had weaker solutions for unknown parameters than
the walls designed for withdrawal or out-of-plane, the program replaces those
parameters in the design wall with the ones designed for C&C loading.
The
procedure has one slight imperfection in that thicker sheathing, which is
optimal for out of plane sheathing strength and for shear design, makes for
weaker nail withdrawal strength due to reduced penetration. So when determining
the strongest wall, one wall may be stronger for out-of-plane design and for
shear but another may be stronger for nail withdrawal. In such a case, the
program uses the wall with thicker sheathing. It is extremely rare for the wall
to fail for nail withdrawal as a result
3. Standard Wall Design Groups for Multiple Walls on Shearline (Bug 2837)
When
changing a standard wall designed as a group for a wall on a line with multiple
walls, the program changed the standard wall for only that wall, retaining the
old standard wall for other walls. However, it changed the materials for all
the walls on the line to the ones for the new standard wall group, because all
shearwalls on a shearline must have the same materials.
As a
consequence, when the program then designed for that shearline, it designed for
both the new and old standard wall groups using the materials for the new
standard wall group. However, the previous standard wall group has different
materials on other shearlines in the building. Therefore a single standard wall
group could be designed for different sets of material selections, and would show different sets of material specifications
in the user input, contrary to the intended purpose of standard walls designed
as a group.
This has
been corrected and a standard wall designed as a group now has just one set of
material specifications.
4. Cub Factor for Stud Spacing Other than 16" (Bug 2888)
The program was
applying the unblocked factor Cub for 16" spacing to stud
spacing other than 16". The correct
factors from SDPWS Table 4.3.3.2 are now applied. .
5. Sheathing Capacity for C&C Design (Bug 2823)
Starting with
version 9.1, all sheathing capacities for out-of-plane C&C design were
mistakenly multiplied by 1.5/1.6, so that the sheathing capacities were 93.75%
of what they should be. This has been corrected.
6. Length of Shearlines which Extend over Part of Structure (Bug 2821)
Starting
with version 10.2, for those shearlines that do not extend to the exterior
perimeter of the building, the length of the shearline was taken to be the
distance between the start of the first wall and the end of the last, ignoring
the gaps between the extreme wall ends and the exterior of the structure.
For lines
with a gap between the end and the perimeter walls, the problem was manifested
in the following ways;
- The diaphragm shear flow shown at the top of the wall in elevation view was larger than it should be
- The Fv/L value shown in the shear design results for a shearline was larger than it should be
- The drag strut calculations are incorrect in a way that depends on the configuration of the wall segments
- The length of the shearline shown in the shearline table was too small
- This problem did not affect shear design of the shearwall and has been corrected
7. Hold-down Stud Width for Capacity and Elongation (Bug 2826)
If there are multiple entries for hold-down capacity for different stud widths, and the entries are listed with the larger stud width before the smaller width and the wall’s stud width is greater than both entries, the program used the capacity and elongation for the smaller stud width even if the larger width was the closer match. This has been corrected
8. Output Warnings for Inadequate Stud Thickness for Hold-downs (Bug 2825)
If you selected a hold-down that is not rated for the thickness of wall studs at the end of the wall, then the program did not design for that hold-down and it used the displacement over-ride entered in the settings. It issued a warning in the hold-down design and hold-down displacement tables to that effect.
Since the wall studs do not necessarily include “cripple” or “jack” studs beneath the window that can contribute to hold-down strength, the program now issues a warning to the effect that extra cripples or jack studs are needed, and continues with hold-dow design using the capacity and displacement for the least thick stud assembly that the hold-down is rated for. The warning is no longer in red indicating a failed design.
9. Zero Capacity Shearlines Using Drywall Screws (Bug 2764)
For some projects, when drywall screws are used, the program assigned zero capacity to shearlines composed entirely of gypsum wallboard, issuing a warning under the shear design table indicating that it is outside seismic design category restrictions even if it was within those restrictions, and it did this for wind design to which SDC’s don’t apply.
This was caused by the program internally assigning nail size of 5 to 5/8” gypsum wallboard. This has been corrected, and size 6 is applied to this material, but for existing project files, the problem could still occur. It can be corrected by manually selecting size 6 and re-designing. .
B. Load Generation and Distribution
1. C&C Wind Load Combination (Bug 2820)
The wind load
combination factor for C&C design of sheathing strength and nail
withdrawal was not updated for ASCE -7
10 for version 10, it remained at 1.0 when it should be 0.6. This has been
corrected.
2. Hold-down
Offset using Center of Wall End Studs (Change 165)
Since typically the centre of the end stud assembly is the location of the centroid of the hold-down force, we now allow you to use the distance from that location to the end of the wall as the hold-down offset used for moment arm calculations.. A checkbox in the Hold-down settings is used to indicate you want to use this value, allowing a different value for each wall in the structure according to the number of end studs entered in Wall input view.
When drawing, the program now draws the tension side hold-down at the full stud thickness from the wall end, because it depicts the bracket, not the center of the bolt through the studs.
3. Hold-down Force Accumulation Tolerance
(Change 169)
The program now accumulates hold-downs forces from the floor above with the one on the floor below when these forces are that are offset by as much as 1.5 " in plan. This is the minimum distance from wall end.
4. Vertical Distribution of Seismic Forces Coefficient k (Bug 2515)
The following problem relates to the co-efficient k from ASCE 7 12.8.3, which is used to distribute forces to the shearwall levels.
a) Use of k to Distribute Forces to Levels
Despite the fact that the program output the value k in the log file, a value of 1.00 was always used in the formula 12.8-12 for Cvx. However, a value of other than 1.00 corresponds to structures greater than 75 feet in height and is quite rare in practice. Nevertheless, the program now calculates the value k used for Cvx for structures with a period greater than 0.5.
b) Period T used to Calculate k
The maximum period Tmax defined in 12.8.2 was mistakenly used to determine k. Now the approximate period Ta is used. The optimal approach would be to use the actual period T as input in the Site Dialog, however due to the small chance that there would ever be a period greater than 0.5 leading to a k other than one, it was not regarded as worth the effort to implement the calculation of different k and Cvx values in each building direction.
5. Nonsensical Seismic Loads on Certain Windows 8 Computers (Bug 2830)
For certain Windows 8 installations, for any structure, all seismic loads were astronomically high nonsense values. This has been corrected.
C. User Interface and Program Operation
1. Log File in Viewer (Feature 153)
The log file which provides load generation and rigid diaphragm analysis details has now been integrated into the program and appears in a window within the program framework. Previously the program invoked the Notepad program to show the log file results. The window is called Load Generation and Torsional Analysis Details. The menu and status bar descriptors have also been updated.
2. Access to Log File After Load Generation (Bug 2811)
Starting with version 10, the "View Log File" action in Shearwalls was disabled until a design had been performed, not after load generation and not when opening an existing file. Thereafter, it, refreshed only upon running a design, not after load generation. In previous versions, the log file was updated and accessible after generating loads, even before performing a design. This functionality has been restored.
When opening an existing project, the log file is now always accessible and shows the results of the load generation from the last session. If no load generation has ever been performed in that file, the log file is still accessible, but shows nothing.
3. De-selection of Walls After Design (Bug 2863)
In implementing the highlighting of failed walls after design, after design the shearlines were deselected in order to show the failed walls if they happened to be selected. However, this caused you to have to re-select the shearlines after design to view them in elevation view, which some users found inconvenient.
Now, the shearlines remain selected after design, and a failed selected wall is shown as a darker red color than unselected failed walls.
4. Failing Walls Not Highlighted as Red in Plan View (Bug 2879)
In the following instances, walls were not highlighted in red if they failed one or more design checks. They have been corrected.
a) Existing Files
When you open a file and run an existing design, then enter wall input view for the first time, the failing walls are no longer highlighted. If you then redesigned they would appear in red.
b) Rigid Distribution Design Final Check Failure
Walls designed for the rigid distribution method which passed on the last design iteration, but then did not pass when forces are redistributed for the final design check, were not showing in red.
5. Crash after Moving Opening then Entering One (Bug 2856)
Occasionally, after moving openings on upper level stories, then creating a new opening on the same wall, the program would crash. This has been corrected.
6. Crash after Standard Wall Change of Multiple Selection (Bug 2883)
Starting with version 10.2, if you designed, then selected two walls at once and changed the standard wall for those walls, the program would crash on the next design. This has been corrected.
7. Crash when Generating Loads on Merged Walls (Bug 2882)
Starting with version 10.2, if walls are segmented then merged again, the program crashes when generating loads. This has been corrected.
8. Creation of Perpendicular Non-shearwalls (Bug 2880)
After one segment of an exterior non-shearwall is perpendicular to the wall to create two perpendicular joining segments, those segments are designated shearwalls rather than non-shearwalls. They otherwise had the same materials as the non-shearwalls. This has been corrected and they remain non-shearwalls.
With the introduction of standard wall design groups with version 10.2, this caused members of the same wall group to have different types. However, this did not cause design difficulties.
9. Crashing and Unpredictable Behaviour for 6 Storey Structures (Bug 2889)
Internal memory
could become corrupted for 6-storey structures. If this happened, the program
would behave unpredictably and possibly crash upon load generation. This has
been corrected.
10. Image File Nomenclature (Change 168)
The references to Windows Metafile in informational messages and other UI locations have been changed to refer to image files or to the list of supported image file types, as these types were introduced with version 10.
1. Update of Inputs Related to Hold-downs (Bug 2825)
Starting with version 10.2, making changes to the Hold-down, Double-bracket, Apply to openings, Number of end studs#, and Hold-down configuration options in wall input view had no effect. The program merely reverted to the previously selected value. This has been corrected.
2. Wall Framing and Hold-down Behaviour on Multiple Selection (Bug 2816)
When multiple walls with varying properties are selected, none of the fields on the Framing or Hold-down sections of Wall Input View were set be blank to signify an indeterminate selection. This does not currently happen for any field in the Framing or Hold-down sections in Wall Input View, instead showing the value of the most recently-selected wall. This is purely a display issue; the actual properties of each wall are correctly maintained.
3. Reversion of Material Changes after Wall Type Change (Bug 2816)
In Wall Input View, after making any changes in the Materials, Framing, and/or Hold-downs groups and then changing the Wall Type without first exiting and entering the the dialog, the recently-made changes were reverted to what they had been before the change. This has been corrected and all changes to the wall materials persist after the type is changed. .
4. Persistence of Nail Size after Change for Multiple Selection (Bug 624)
Starting with version 9.1 of the software, if you selected multiple walls and different wall materials for each one, then changed the material type, and then selected a nail size, the nail size selection did not persist and reverted to what it was before you selected the members and changed the size. This has been corrected
5. Enabling of Double-Bracket Boxes in Openings View (Bug 2813)
In openings view, if no wall is selected, all inputs were greyed out except for the two double-bracket checkboxes at the bottom. With no wall selected, or with a wall with no openings selected, clicking on one of these the double bracket checkboxes caused a crash. These controls are now disabled when no walls are selected, and will not cause a problem when clicked.
6. Editable Ply and Panel Marking Input Box (Bug 2807)
Starting with version 9, the fields for that are used for Plywood plies and span rating are editable, they it should be non-editable selection lists Typing data into these boxes did not cause a problem; the program simply ignored them and used the default for the designed thickness.
1. Formatting of Seismic Parameters Table in Log File (Bug 2878)
The rightmost 4 headers in the seismic parameters table in the log file are offset so they appear above the values corresponding to the parameter next t them, for example, Cs appears above the numbers for Csmin.
2. Color of Text in Load Generation Legend (Bug 2815)
The Unfactored generated shear load and Vertical elements required items in the legend in Plan View that appears on load generation are now coloured blue like the rest of the legend, not orange.
3. Standard Wall Name in Plan
and Elevation View (Change 170)
The standard wall name shown on the walls in plan view and in elevation view, which was introduced in version 10, is now shown only once on a shearline, as all shearwalls on a shearline must have the same materials. If lines have both shearwalls and non-shearwalls, then standard wall names can be shown more than once.
4. Location of Perforated
Shearwall Label In Elevation View (Bug 2891)
The text in Elevation view that says a shearwall is perforated and gives the perforated factor sometimes obscured the hold-down force output, particularly for short walls. This text has been moved downwards to be below the hold-down force output.
5. Interior Walls on Same Line as Exterior Walls in Component and Cladding Table (Bug 2885)
When a shearline goes from the interior to the
exterior of the structure, the program output a line of design results for
walls that are on the interior of the structure and are not loaded. Those lines
would show zero nail withdrawal force but non-zero sheathing force. These lines
have been removed.
6. Display of Non-shearwalls
that Fail due to C&C Design (Bug 2732)
When a
non-shearwall failed due to C&C design, it was not highlighted in red as a
failed wall in Plan View. This has been corrected.
7. Relation
to Escarpment Crest in Topographic Information Output
The program showed “50 ft above crest” and “50 ft
below crest” for the output of the relation of the building to an escarpment.
This has been changed to “Upwind of crest” and “Downwind of crest” to conform
to the terminology of ASCE 7 26.8.1.
8. Shear Design Legend Clarifications (Change 172)
The shear design legend has been clarified as follows:
- indicate that H/W/Cub is for critical segment
- emphasise that wall capacity is for sum of segments on wall
- indicate "combined" means interior and exterior
- clear up shear force wording.
Shearwalls
10.24 – July 18, 2014 – Hot fix
This
version was sent to individual users to address bugs 2856 Crash after Moving
Opening then Entering One and 2820 C & C Wind Load
Combination for Sheathing Design These bugs are described in the changes to
Version 10.3, the first version released to the
general public with the fix.
Shearwalls
10.23 – May 22, 2014 – Hot fix
This
version was sent to an individual user to address bug 2837: Standard Wall Design
Groups for Multiple Walls on Shearline. This bug is described in the changes to Version 10.3, the first version released to the
general public with the fix.
Shearwalls
10.22 – May 13, 2014 – Hot fix
This
version was sent to an individual user to address bug 2830:: Nonsensical Seismic
Loads on Certain Windows 8 Computers. This bug is described in the changes to Version 10.3, the first version released to the
general public with the fix.
Shearwalls
10.21 – February 5, 2014 – Design Office 10, Service Release 2a
1. Update of Inputs Related to Hold-downs (Bug
2683)
Making
changes to the Hold-down, Double-bracket, Apply to
openings, Number of end studs, and Hold-down
configuration options in wall input view had no effect. The program merely
reverted to the previously selected value. This has been corrected.
2. Update of Inputs for Identical Standard Wall
Groups (Bug 2775)
When in
the standard wall input view, if multiple standard walls have the exact same
materials and framing inputs, then sometimes the Design as Group checkbox and
the Standard Wall dropdown list were showing the values for one of the other
identical standard walls instead of the selected standard wall.
3. Location of Standard Walls File for Network
Installations (Bug 2776)
For
network installations, the file that stores the standard walls was previously
located on each local client machine. The standard walls file is now located on
the network server in the same location as the materials and hold-down
databases. This was needed now that the
standard wall groups are used for design grouping.
Shearwalls
10.2 – January 21, 2014 - Design Office 10, Service Release 2
1. Design and Load Distribution Processing Time
The time
taken to design shearwalls and to distribute and draw loads and forces has been
markedly improved, by a factor of at least twenty, so that delays that used to
occur in the operation of the program have been reduced to manageable levels.
a) Slow Processing Time when Designing Complicated Structures (Bug
1837)
When a
project had a combination of many shearlines, many exterior surfaces, many
blocks, and multiple stories, the time taken to analyze and design the
structure could be very slow, sometimes as much as 5-10 minutes. Such a
structure now takes 10-20 seconds. Smaller, less complicated structures also
design much faster, so that a building that used to take 30 seconds to design
now designs virtually instantaneously
b) Slowdown in Updating the Drawing of Loads (Bug
2750)
Once
loads had been generated, every time you went into Load Generation action or Loads
and Forces action, the drawing of the building and loads in plan view would hang for many seconds,
especially for complex buildings with a large number of loads. This also happened while you scrolled the
view, selected walls, moved the window, edited loads, etc.
This has
been corrected and the drawing of the loads has been accelerated by a factor
ranging from a small amount to up to several thousand times, depending on the complexity
of the building. The delay in
drawing loads is now a fraction of a second and manageable.
Previously, when wall parameters were left as unknown, Shearwalls designed separate walls for wind design, seismic design, rigid distribution, flexible distribution, and both force directions – a possibility of 8 designed walls for each physical wall in the structure. In practice, at most 4 walls would be designed, because forces in opposing directions are similar, and often only two or three walls would result. It was left to the designer to compare these walls manually and choose the one that was strong enough for all load cases. If you wanted to see design results for the selected wall, it was necessary to “accept” the design for that case and to run the design again.
Now, the program automatically determines the worst case of wind and seismic, and for opposing force directions, and designs one wall that is evaluated for all these load cases. Optionally, you can also have the program determine the worst case of rigid and flexible diaphragms.
a) Worst Case Wind vs. Seismic Load Case (Feature 12)
i. Shearwall Design
Previously, the program determined the wall parameters needed to resist the forces from the applied wind loads, and then did so for seismic loads separately. As a result, the program could create separate wall groups for the same physical wall, one for wind design and one for seismic design.
The program now compares the walls designed for wind and seismic and selects the wall that has the highest capacity. That wall is then used to redistribute forces on the line if deflection is the force distribution criterion, and to redistribute forces to the shearlines for the rigid diaphragm procedure.
ii. Output – Shear Design Table
The wall groups are indicated by numbers in the Shear Design table, which are defined in the Sheathing and Framing Materials by Wall Group tables. For a particular wall, the same number now appears for seismic and wind design; previously they could be different.
In the Critical Response column of the table for wind design, the program outputs an “S” beside the response ratio if the critical case was seismic and the wall had unknown parameters. Similarly, a W is printed beside the column in the seismic table if the critical case was wind. This alerts you to the reason that a wall might be designed with materials that are much higher than needed to resist the loads from the design case shown.
The legend has been modified to explain the meaning of these letters.
b) Worst Case Rigid Diaphragm vs. Flexible Distribution Method (Feature 69)
With the
2010 edition, ASCE 7 provided less restrictive conditions for which flexible
diaphragm assumptions can be made for seismic design, such that any light frame
construction without concrete topping can be idealised as flexible, as long as
each shearline complies with storey drift limitations in 12.2-1 (which are
ordinarily required to be met only at the center of mass of the structure).
Despite
this, many designers prefer to consider diaphragms to be semi-rigid, and in the
absence of a complex numerical model of the structure, wish to design for the
worst case of rigid and flexible diaphragm distribution, to cover the whole
envelope of possible diaphragm rigidities. Shearwalls now allows for that
approach.
i. Design Setting
A checkbox has been added to the Design Settings called
Worst-case rigid vs. flexible diaphragms (envelope design).
The default for new program installations that this setting is on, but this can be changed. The setting is disabled if you have not chosen to design for both rigid and flexible diaphragms ( the choice is in the Structure input).
If the Worst case rigid vs. flexible setting is not selected, program determines the wall parameters needed to resist flexible diaphragm distribution forces, and then does so for rigid forces separately. As a result, the program can create separate wall groups for the same physical wall, one for rigid diaphragm design and one for flexible design.
If the setting is selected, the program first designs a wall for flexible diaphragm forces. When designing for rigid forces, if they are lower than flexible force, the program simply uses the wall designed with the flexible force. If they are higher than the flexible force, it replaces the wall designed for flexible forces with the one designed for rigid forces. For deflection-based intra-shearline distribution, the wall is then processed again for flexible forces on the next iteration of the design procedure, as the distribution of forces within the shearline may change slightly due to the new wall stiffness.
iii. Output – Shear Design Table
The wall groups are indicated by numbers in the Shear Design table, which are defined in the Sheathing and Framing Materials by Wall Group tables. If you have selected the Worst-case rigid vs. flexible diaphragms design setting, then for a particular wall, the same number appears for rigid and flexible design. If that setting is not selected, they can be different.
Please note that if the Worst case rigid vs. flexible setting is set, a the wall materials appearing in table for rigid diaphragm design may have been designed for a higher force for flexible diaphragm design, and vice-versa. If the program designs walls that appear to be much stronger than needed, this is the most likely reason.
c) Worst Case of Opposing Force Directions
It is possible for the force in one direction to be slightly different than the force in the opposing direction. For wind design, this can occur for a mono-slope roof or eccentric ridge line. For both wind and seismic design, it can occur when forces are distributed due to deflection and there are asymmetries in the hold-down devices or hold-down forces. An example of this is when openings are do not line up and vertical compression forces from the floor above are added to tension forces from the floor below.
In rare circumstances, such difference could cause the program to design a different wall for the east->west direction than the west<-east direction, and similarly for north-south walls.
i. Shearwall Design
The program now determines the largest force on any segment in the shearline, in either direction, and designs the wall materials for that force.
ii. Output – Shear Design Table
When different forces existed, two lines of results instead of one were output in the Shear Design table for each wall in the shearline. If different wall materials were selected by the program for these forces, a different wall design group number could be shown for the two directions.
The program still outputs separate design results for the opposing force directions if they are different, but this is to show the performance of the wall with respect to the different forces. The design group number shown for the opposing directions is now always the same.
d) Design Failures
There exists a small possibility that when distributing loads using the rigid diaphragm method to a stronger wall than was designed using that method, the rigid distribution routine could load the shearline to the extent that the wall fails despite being stronger than the one that previously passed. This can happen when a wall designed for seismic is used to resist wind loads (or vice versa), or when a wall designed for flexible distribution is used for rigid diaphragm forces.
Although unlikely, it has the highest chance of happening when using deflection-based design and the effect of increased stiffness is greater than the increase in wall capacity.
If this occurs, the program alerts you to the situation
via a note under the Shear Results
table. The wording of the existing note that appears if this occurs for other
reasons has been modified to take into account this possibility.
The same thing could conceivably happen for the flexible diaphragm method and
distribution within a shearline using
deflection based rigidity, but it is highly unlikely because all segments on
the wall have the same shearwall materials.
e) SHEARLINE, WALL and OPENING DIMENSIONS Table
Because this table no longer shows a list of design groups for each wall, showing at most two for rigid and flexible design, the heading to this column is “Wall group rather than Wall Group(s). A note below the table has been added when worst case rigid and flexible is not selected, explaining why two group numbers may appear.
3. Wall Design Groups (Feature 17)
The program now allows you to specify that groups of walls with unknown parameters wind up with the same material specification after design. The program designs the wall for the most heavily loaded wall in the group.
For example, all interior walls on a certain level, or all exterior walls in the structure, can be specified to be the same. Previously such walls would often have slightly different material specifications, which is not usually practical for construction.
a) Standard Walls
The program uses the existing Standard Wall mechanism for this feature. You are able to indicate which standard wall groups are to be designed as a group, and within the standard wall group, which walls are to be included in the group design. It may be necessary therefore to make more standard wall groups than were previously used to make default walls.
For example, if you had a Standard Wall called Exterior Shearwalls that was used as a starting point for design of all exterior walls, but want the same set of wall materials to be designed on each story of the structure, but possibly lighter walls on the upper storeys, then you would make 4 new groups called Exterior Shearwalls Lev 1, Exterior Shearwalls Lev 2, etc.
b) Design as/in Group Input
A checkbox has been added to the Standard Wall input called Design as a group and in the regular wall input mode called Design in group . The checkbox in the standard wall mode means that all the walls of that standard wall that also have the checkbox checked will be designed as a group in the sense that they will wind up with identical materials after design. Those individual walls that do not have the checkbox checked are treated as if they were not part of a standard wall group. Those standard walls that do not have the checkbox checked function as current standard walls, that is, as default walls only.
i. Default Setting
The standard wall checkbox will default to being checked if a new standard wall is made. The standard walls shipped with the program will have the checkbox checked by default.
ii. Updates
If you uncheck the Design as a group check box for a standard wall, then all the checkboxes for walls of that group are unchecked and disabled. If you check a standard wall box that had been unchecked, then all of the standard walls in the program are be checked and enabled.
If the you select a Standard Wall for an individual wall when previously it had a different standard wall or no standard wall, then the individual wall’s checkbox will be checked and enabled if the standard wall box is checked. If it is not, it is unchecked and disabled.
If you change a wall so that it becomes identical to a standard wall and then becomes one of those standard walls, the checkbox will be unchecked regardless of whether the standard wall Design as Group checkbox is checked or unchecked, but it will still be enabled. This is because the wall was not made a standard wall deliberately, so you are unlikely to want it to be grouped with those walls for design.
iii. Default Walls
When walls are made in the program using standard walls, then the individual wall’s checkbox will be checked and enabled if the standard wall box is checked. If it is not, it will be unchecked and disabled.
iv. Standard Wall Deletion
If you delete a standard wall, then the program goes through all the walls that had been that standard wall, and unchecks Design in group
v. Previous Versions
Walls from existing files from versions before the feature was implemented have their individual wall Design in group checkbox unchecked by default.
c) Wall Attributes
Previously, when attributes such as materials or wall type were changed for individual walls, the wall would no longer be identified as being a standard wall. If standard walls are changed, then all the walls that were created with that wall were not identified with that standard wall. For those standard walls designed as groups, this has changed, and membership in the standard wall group persists through material changes.
i. Change of Wall Attribute
If you change an attribute of a wall that is currently one of a standard wall group, and both the standard wall and the individual wall are to be part of a design group, then the program will issue a warning saying “All walls of the [standard wall group] will also have the selected change.” There is a “Don’t show this box again checkbox in the message to allow you to avoid having the box appear repeatedly.
If you don’t want the attribute to change for all walls in the group, then just change it back to what it was and deselect the Design in Group box for those walls you do not want to change.
If you change an attribute of a wall that is a standard wall but does not have the Design as Group checkbox checked, then the program will allow the change with no message and in most cases it will cause the wall to no longer be part of the standard wall group. No other walls will receive the change.
ii. Change of Standard Wall Attribute
If you change at least one attribute of a wall that has the Design as Group box checked, when exiting the box, the same message as for individual walls appears, saying all members of the Standard Wall group will receive the change, allowing you to suppress further instances of the message.
If the Design as Group box is not checked, then a change in wall attributes will cause all the walls that were previously one of the standard walls to no longer a standard wall, as the program currently behaves.
d) Multiple Standard Walls with Same Materials
Previously, the program would not allow you to create more than one standard wall with the same material specification. For those standard walls that are designed as a group, this restriction has been relaxed in order that you can use for example the same material specification with unknowns that become different wall specifications when the unknowns are determined by the program in order to meet design requirements.
For example, you can have different standard wall groups on each floor of the building, each with the identical materials when unknowns are included, which however become different walls when the program designs for the different loading scenarios on each floor.
i. Automatic Identification of Standard Wall Group
Currently, if the program identifies that a change in a wall makes it identical to a standard wall, it assigns it to that standard wall. If you have multiple standard walls with the same specification, it randomly chooses which of these standard walls to assign the wall to. This has little impact, because the Design in group is unchecked in this case. You can manually change the standard wall the wall is associated with and check Design in Group if you want it to be grouped with a different wall.
e) Standard Wall File Synchronization
When a file is saved with standard wall groups, and the standard wall definitions are later changed, or standard walls are deleted, while in another project, and the original file is opened up again, some of the grouped walls have no standard wall associated with them.
If this happens, new standard walls are created with the materials from the grouped walls, and given names Std Wall 1, Std Wall 2, etc. These walls are later saved as standard walls that can be opened with any project. Toc can then either delete them, rename them, or reconcile them with the changed standard walls that were originally used to create them.
f) Design Procedure
After the design iterations, and before the final design check, the program compares the design capacities of all walls in a group. I then the materials of the wall with the highest capacity to all the walls in the group, then recalculates the wall deflections, redistributes loads to the walls, and outputs design tables for the new walls.
i. Design Failure
It is possible for the new load distribution to create a situation that the critical wall in the design group might elsewhere fail elsewhere on the structure where a weaker wall had passed. When this happens, a warning appears in the Shear Design table of the output. The existing warning that appears when this occurs for other reasons has been reworded to reflect this possibility,
ii. Wall Grouping
The existing system of comparing all the designed walls to establish design groups with identical materials, which are identified by numbers, has been retained. The fact that walls within a Standard Wall group will have the same materials cause them to be grouped with the same group number.
Walls that are not part of Standard Wall groups are also grouped and assigned group numbers as they currently are.
g) Accept Design
Changes have been made to the recently added Accept Design feature because there are no longer separate designs for wind and seismic, so the choices in the selection menu are now just Rigid Diaphragm and Flexible Diaphragm” rather then Rigid, Wind, etc.
The sub-submenu item has been changed to say Accept from Accept Design. .
When you have activated the Worst Case Rigid and Flexible feature, , both Rigid and Flexible are checked but disabled, and the Accept item is the only one that is enabled.
h) Output
i. FRAMING MATERIALS by WALL GROUP Table
The name of the Standard Wall associated with a wall group, if there is one, is included in a column that has been added to this table. It is possible that more than one Standard Wall yields the same materials when designed; in that case the line is repeated with the same group number. If there is no Standard wall associated with the group number because it came from walls that were not grouped, the line appears blank.
The table has been renamed accordingly to FRAMING MATERIALS and STANDARD WALL by WALL GROUP.
ii. SHEAR DESIGN Table
A hat symbol (^) appears beside the wall group number for the wall that is critical for that group, that is, the wall that had the heaviest loading and for which the wall materials designed were used for all other walls in that group.
The legend has been modified to explain this and to refer to Standard Wall groups.
iii. SHEARLINE, WALL and OPENING DIMENSIONS Table
The legend has been modified to refer to Standard Wall groups.
iv. DEFLECTION Table
The legend has been modified to refer to Standard Wall groups.
B. Load Generation, Load Distribution, and
Shearwall Design
1. Extra Dead and Uplift Loads
over Wall Openings (Bug 2740)
When
C&C loads were generated, the program erroneously created extra wind uplift
and dead loads over all wall openings. These loads were then factored into the
hold-down forces. In elevation view, the extra loads over openings and extra
hold-down forces were added to existing uplift loads/forces and superimposed
over existing dead loads/forces.
The
hold-down forces introduced small discrepancies results in the hold-down design
and deflection analysis. (The errors were small because the uplift and dead
forces largely cancel.) They also
introduced differences in west-east vs east-west design that caused the program
to needlessly design and output both directions when they were actually the
same. Extra C&C loads were also
created, making the reporting of C&C results in elevation view
illegible. The extra C&C loads did
not affect suction design.
All
of these problems have been corrected.
2. Torsional Moment Amplification Factor Ax
The
following problems are related to the torsional moment amplification factor Ax
from ASCE 12.8.4.3, which Is required for rigid distribution, seismic design
category C or greater and when a torsional irregularity exists. And have been
corrected.
a) Accidental Eccentricities and Ax
(Bug 2737)
When determining
the deflections on extreme shearlines used for the calculation of Ax, the
program was using the deflection due to the factored shear value for the lesser
of the plus/minus accidental eccentricities, which is 1.0/0.7 too large, and
comparing it with the unfactored value for the larger of the plus and minus
eccentricities. This resulted in larger deflections for the lesser of the
plus/minus forces than they should have been, and are sometimes larger than the
deflections from the larger shear force.
This could result in an Ax value larger than it should be.
This has
been corrected and the unfactored shear value is used to compute deflections
for both plus and minus eccentricities.
b) Torsional Irregularity and
Amplification for Wall Lines with Zero FHS (Bug 2738)
When determining
the deflections on extreme shearlines, the program was failing to identify
those exterior wall lines that do not have full height sheathing, so are not in
fact shearlines. It was assigning zero storey drift at the building edge in
those cases, which also caused the program to be more likely than it should
assign a high Ax.
Now, if
the outermost wall lines do not have full height sheathing, the program uses
the next closest shearline with full height sheathing, which may in fact
consist of interior walls.
The
following problems are related to the determination and reporting of story
drift from ASCE 7 12.8.6, and have been resolved.
a) Shearline used for Story
Drift for Torsional Irregularities (Bug 2736)
In those
cases that ASCE 7 12.8.6 requires that only the story drift at the edge of the
building is to be considered, the program was examining any shearline with
exterior walls rather than only those shearlines at the extremities of the
building. Furthermore, it was not restricting its search for such shearlines to
the floor being designed. Now the program examines only the two shearlines at the extreme
locations of the building, and examines shearlines on the story shown in the
Story Drift table. The cases in
which the extreme shearlines are required are rigid distribution, seismic
design category C or greater and a torsional irregularity exists.
b) Zero Center of Mass for
Storey Drift for Co-ordinate Shifted Buildings (Bug 2759)
For those building situated such that the location of the center of mass (CM) in relative co-ordinates is outside of the extent of the two adjacent shearlines to the CM measured in absolute co-ordinates, the center of mass and deflection shown in the story drift calculations are zero rather than the expected values. This can be expected to happen for buildings whose west or south face is located a significant distance from the origin (0,0).
The buildings for which storey drift calculations use the center of mass are those that are not in seismic design category C, D, E or F having torsional irregularity (ASCE 12.8.6)
4. Non-convergence of Deflection-based Distribution to Segments (Bug 2770)
Occasionally, Shearwalls is unable to distribute forces to the shearwall segments by equalizing the deflection of each segment due to non-convergence of the numerical routine used.
a) Warning Message
If this happens, the program now outputs a note below the Shear Design table indicating the affected shearlines.
b) Inconsistency of Deflection
and Design Forces
In such a case, the force on the segment used for shearwall design could be markedly different than the force used for deflection analysis. This has been corrected, and they are .now the same. However, it should be noted that these forces do not result in equal deflections on the shearlines, and the value selected is just one in the succession of non-converging iterations that can oscillate between very different values. We recommend turning to capacity-based rigidities for load distribution if this occurs.
5. Non-Structural-Wood-Panel Perforated Shearwalls (Bug 2771)
Shearwalls allowed walls that are not made of structural wood panels to be perforated walls, although this is not permitted by SDPWS 4.3.5.3. This has been corrected, and the program does not allow the selection on non-structural wood panels on both sides or the only side of the wall when perforated shearwalls are selected, or the selection of perforated shearwalls when only non-structural wood panels are selected. Non-structural wood panels are usually gypsum drywall or fibreboard.
6. Drywall Screws Design Values (Bug 2769)
The
following related to the shearwall design strengths when drywall screws are
used have been corrected.
a) Blocking for ½” Thickness
For ½ “ thickness drywall, the values for blocked shearwalls were used when there was no blocking, and vice-versa, except for 24” stud spacing, in which case the correct values were used.
b) 5/8” Thickness Values
For 5/8” thickness drywall, the values for cooler nails were used instead of drywall screws.
7. Wind Suction Output with Single Analysis Method (Bug 2767)
When either the flexible analysis or rigid analysis methods are turned off in the Structure dialog, the Wind Suction Design output table was reporting two lines of suction data for each shearline. The first line showed the actual suction capacity, the second line shows zero capacity. This was also causing a failure warning message to be shown below the table even though the suction design passed. These problems have been corrected
8. Hold-down Forces due to
Uplift Shear Force t for Rigid Diaphragms (Bug 2739)
When a
perforated wall uplift shear force t (SDPWS 4.3.6.1.2), overlaps with an opening
on the floor below, the uplift shear t force is transferred down to the floor
below by creating hold-down t forces on the edges of the opening. These hold-down t forces at the edges of
openings on the floor below were not being created for the rigid distribution
method. This has been corrected.
9. Windward Loads for Roof
Angles between 45 and 60 (Bug 2725)
For the
Directional (all-heights) wind load generation method, when the slope of the
roof was between 45 and 60 degrees (non-inclusive), the pressure coefficient Cp
on the windward side of the roof was always zero,
when it should be between 0.3 and 0.6. The program therefore failed to generate
wind loads for the roof panels on the windward side. This has been corrected and loads
are generated for all angles of roof slope.
10. Identification of Seismic
Design Category E (Bug 2723)
The
Seismic Design Category E is to be used when S1 >= 0.75 (ASCE
7-10 Clause 11.6), however, Shearwalls was checking if SD1 >=
0.75 instead. This was causing the
Seismic Design Category E to be used instead of category D. The seismic design category affects
design notes in the output and seismic material restrictions. GWB sheathing and
diagonal lumber sheathing aren't allowed for Category E, but are for Category
D.
11. Crash on Load Generation
for Closely Spaced Walls. (Bug 2687)
The
program sometimes crashed during seismic load generation when walls are
positioned such that they could belong to more than one shearline.
C. User Interface, Output, and Program Operation
1. Display of Wall Group Name (Feature 102)*
The program now allows you display the name of the standard wall used for each wall in both Plan view, which is now also the wall design group. This is controlled by a checkbox in the Display group of the Options setting. It defaults to being checked.
2. Input of Invalid Wall Location (Bug 2754)
Changing
the location of a wall via the input field in the Wall Input dialog of a wall
to a location that was invalid because it is outside the building perimeter,
intersects with another wall, etc., caused the program to crash. The program
now shows an error message and does not allow the wall to be made.
3. Subtract Hold-down Offset
From Moment Arm Setting (Bug 2731)
The
hold-down setting to subtract the hold-down offset from the overturning force
moment arm operated in reverse, that is, when you selected that the offset was
to be subtracted, it didn’t subtract, and vice-versa. This has been corrected and the program
subtracts the offset when you indicate so in the settings.
4. Level Selection for Design Results Output (Bug 2772)
Starting with version 10, the program no longer allowed you to filter the design results output via the levels selected, showing only those results for the selected levels. The level selectors were disabled and both set to 1, but the design results showed all levels. This has been corrected and you can once again select a range of levels for which to view the design results.
5. Eccentricity of Wind Loads
in Site Information Dialog (Bug 2717)
In the Site Information dialog, when the Dynamic analysis checkbox was unchecked,
pressing the Estimate button caused
the Eccentricity values to change
unexpectedly. Eccentricity for
north-south loads was reduced by a factor of 100 and for east-west loads
by about 1000. These values were retained and used for design
if they are not changed back.
6. Display of Failed Walls due to C&C
Design (Bug 2732)
When
walls fail due to C&C design only, the note in plan view said that it fails
for flexible wind design; however, flexible distribution is not relevant to
C&C design. This has been
corrected by indicating that it fails for C&C design instead. If it fails
for both C&C and MWFRS design, both are indicted in the note.
7. Default Setting for Save as
Default (Change 159)
The
default setting for Save as default for new files for Default Values and Company Information
settings has been changed from being unchecked by default to being checked by
default.
8. Reporting of Wall Segment Shear Force V for
Openings at Start of Wall (Bug 2721)
When a
wall has an opening positioned at the start of the wall with zero offset, the
total Shear Force V reported for the next wall segment was
incorrect in a random way. This was a
problem with the output report only; the correct value is used in design. The
correct shear value V now appears in the output report.
9. Shearwall Wall and Opening Dimensions Table
Legend (Change 162)
The Shearwall Wall and Opening Dimensions
table legend has been updated to make it more readable and fix minor typos.
Each item now appears on a separate line, similar to other legends. Improved
explanations are given for wall groups and wall length.
10. Crash on Results Output for Windows 8 (Bug 2758)
For some
Windows 8 systems, for any building, even a simple rectangular building with no
openings, after pressing the design button and when the progress bar indicated
that the program is outputting results, the program crashed. This no longer
occurs for version 10.2.
11. Plan View Update Quality (Change 161)
The plan
view now draws more smoothly without flashing on changes or when scrolling
12. Building Code Factor Output (Change 163)
The factor shown as Building Code Capacity Reduction in the Design Settings section of the results output now reads Building Code Capacity Modification to match the nomenclature in the Design Settings.
13. Appearance of Load Arrows (Bug 1952)
For large structures, the arrows in Plan View representing applied loads became much more widely spaced than for smaller structures, and the arrowhead was not visible. This has been corrected and the appearance of the load arrows is similar for large and small structures.
Shearwalls 10.13 – Nov 22, 2013 – Hot Fix
This
version was sent to an individual user to address bug 2750 Slowdown
in Plan View with Many Loads. This bug is described in the changes to
Shearwalls 10.2, the first version released to the general public with the fix
Shearwalls
10.12 – Nov 6, 2013 – Hot Fix
This
version was sent to an individual user to address bugs 2636-2638 regarding
torsional irregularities and the torsional amplification factor. These bugs are described in the
changes to Shearwalls 10.2, the first version released to the general public
with the fix.
Shearwalls 10.11 – Aug 12, 2013 - Hot Fix
This
version was sent to an individual user to address Bug 2687 Crash on Load Generation for Closely Spaced Walls. This bug is
described in the changes to Shearwalls 10.2, the first version released to the
general public with the fix.
Shearwalls
10.1 - July 24, 2013 – Design
Office 10, Service Release 1
This
version released to address following problems in Shearwalls 10.0:
1. Regeneration of Seismic Loads (Bug 2685)
In the generate loads window, when you pressed
on the Delete all generated loads, Delete all and regenerate or Generate loads on selected levels , the
previously generated seismic loads were not deleted. This resulted in multiple copies of the
seismic loads being created depending on how many times the buttons were
pressed, which was causing the accumulated seismic loads and forces to be too
large.
2. Load Type Checkbox in Generate Loads
View (Bug 2684)
The
checkboxes to enable/disable wind and seismic load generation in the generate
loads window were not visible, unless you clicked on the area where the
checkboxes usually appear. This has been corrected.
Shearwalls 10 – July 4, 2013 –
Design Office 10
Version
10 of Shearwalls updates several design codes and standards used in the
program. The details of the associated changes to the program appear throughout
the rest of this list of changes, this section just identifies the design
standards changed.
1. Standards Updated (Feature 195)
The
implementation in Shearwalls the IBC has been updated from the 2009 edition to
2012, the ASCE 7 from 2005 to 2010, and the NDS from 2005 to 2012 as follows:
a) ICC International Building Code (IBC 2012)
Version
10 of Shearwalls implements the 2012
IBC, whereas Version 9 implemented the 2009 version.
IBC 2012
references ASCE 7 10 for all wind and seismic load generation procedures, so
that the updates for ASCE 7 make the program compliant with IBC 2012 in this regard.
The
changes to the load combinations for ASCE 7 10 are identical to those in IBC
2012. Throughout what follows, we will refer to these changes as being due to
ASCE 7 with the understanding that the same changes are in IBC.
IBC 2012
references the AWC Special Design Provisions for Wind and Seismic (SDPWS 2008)
for all design provisions, except those using staples, which are not permitted
by SDPWS. Shearwalls does not include staples, so all procedures in the program
comply with IBC by complying with SDPWS. SDPWS 2008 was implemented in version
9 of the program, so no changes in this regard were required for version 10.
b) ASCE 7 Minimum Design Loads for Buildings and
Other Structures (ASCE 7-10)
Version
10 of Shearwalls implements the 2010
ASCE 7, whereas Version 9 implemented the 2005 version. There were significant
changes, particularly for wind load combinations and wind load design
procedures. In addition, WoodWorks
re-evaluated the previous implementation of wind and seismic load generation
and design, and included significant improvements not directly related to
changes in the design code.
c) ANSI / AWC Special Design Provisions for Wind
and Seismic (SDPWS 2008)
The
SDPWS had been updated from the 2005 version to the 2008 version for Shearwalls
9; however the menu item that allowed you to view the On-line SDPWS had not
been changed and still showed SDPWS 2005 ( the document shown was 2008) This has been corrected.
d) ANSI / AWC National Design Specification for
Wood Construction (NDS 2012)
Version
10 of Shearwalls conforms to the NDS 2012, whereas version 9 conformed to NDS
2005. The few shearwall and diaphragm provisions that were in the 2005 edition
have been removed from NDS 2012, which now just refers to the SDPWS.
2. References to the Design Standards
The
references to design standards have been updated in the following places,
especially for ASCE wind loads, which were completely re-organised and
re-numbered for ASCE 7-10.
a) Welcome, About Shearwalls, and Building Codes
Dialog
The new
design standards implemented are listed in the Welcome dialog box that appears on program start-up, and can be
invoked later via the Help menu, and
in the About Shearwalls box from the
help menu. More detailed information is given in the Building Codes dialog box invoked from the Welcome box.
b) Messages, Notes, and Table Legends
The
references in all informational and warning messages, design notes in the
program Design Summary, and table legends in the Summary, have all been updated
for the new references.
c) Log file
The log
file, which gives the equations used for wind and seismic load generation and
for torsional analysis, has been updated for the new design code references.
The
header to the log file now says that it implements IBC 2012 and SDPWS 2008, as
well as the existing ASCE 7 references.
d) Help File
The Help
documentation has been updated both with the new references and with any
changes in explanations needed.
With ASCE
2010, the terminology “Directional” is used to refer to what used to be called
“All Heights” loads (Chapter 27), and the term “Envelope” is used to refer to
what was “Low-rise”. The old terminology is still used in the captions to the
Figures giving the particulars of these methods. This change has been implemented in the
program as follows:
a) Design Settings
Wind
load design procedure is changed to Wind load generation procedure
ASCE
7-05 All heights is changed to ASCE 7-10 Directional (All Heights)
ASCE
7-05 Low-rise is changed to ASCE 7-10 Envelope (Low-rise)
b) Site Dialog
In the
Site Dialog, the methods are given as
ASCE
7-10 Directional Procedure for buildings of all heights (Ch. 27)
ASCE
7-10 Envelope Procedure for low-rise buildings (Ch. 28)
c) Input Echo in Results Output and Log File
The same
identifiers that appear in the Design Settings input appear in the Results
Output echo and in the title to the wind load procedure in the Log file. .
d) Shear Design Results Output
In the
introduction to the Shear Design
section of the Design Results, for the low rise method, the subheading that
used to say ASCE 7 Figure 6-10
Windspeed-generated loads now says ASCE
7 Envelope (Low-rise) Loads. For consistency, a subheading ASCE 7 Directional (All Heights) Loads has
been added for the directional method.
There is
no longer an importance factor I for wind design. Instead different maps are provided for
different Risk Categories (ASCE 26.5) instead of a single map with importance
factors to be applied for each risk category. Therefore, the importance factor has
been removed from Shearwalls for wind design as follows:
a) Occupancy
The Occupancy input in the Site Information
dialog has been moved from a general area to the Seismic design section and
renamed Risk Category. The associated
echo of this input in the Design Results has been moved to the seismic section.
The
output no longer has shows IBC Occupancy
and ASCE Equivalent. There are still
substantial differences in the phrasing and the specification of buildings
included between ASCE 7 and IBC, but no consequential differences in making any
of the four selections.
The
input echo has also been removed from the wind load section of the log file.
b) Importance Factor I
Generated
wind loads are no longer multiplied by an importance factor I. The output of this factor and of the symbol I
in the wind load equation has been removed from the log file output.
c) Hurricane-prone Regions
The wind
importance factor for ASCE 2005 was influenced by the proximity to shoreline
for hurricane-prone regions. As there is no longer a wind importance factor,
the checkbox for Hurricane prone region
has been removed from the Site Information dialog.
3. Simultaneous Case 1 and Case 2 Load Cases
Previously,
if you wanted to generate All Heights Case 2 loads (75% loading plus 15% moment
– Figure 27.4-8) for torsional analysis with the rigid diaphragm procedure, you
had to use these loads in a separate design run and manually compare the
resulting design to determine the critical case. The program was not capable of
generating Case 1 and Case 2 simultaneously, or using the worst of these cases for
design.
Now
the program generates both Case 1 and Case 2 loads and uses the heaviest
loading from each of these cases and the minimum load case as the design
shearline force on each line.
a) Design Setting
The
Design Setting allowing you to choose between Case 1 and Case 2 wind loads has
been removed; the program now generates loads and distributes forces for both
these cases at all times.
b) Show Menu
Previously,
changing the show menu between Case 1 and Case 2 triggered a regeneration of
loads, prompting you to accept the new loads. Now it merely shows the existing
loads and forces for the selected design case on the screen.
c) Adding a Load or Direct Shearline Force.
Previously,
when you added a load, or added a direct shearline force with “Both” selected
as the force distribution method, with Case 2 selected in the Design Settings,
Case 1 loads at 100% Case 2 loads at 75% were created. Case 1 loads were
restricted to flexible diaphragms. If Case 1 was selected, only Case 1 loads at
100% were created.
Now,
both Case 1 and Case 2 loads and forces are always created when a load or force
is added. The added loads apply to both rigid and flexible diaphragms (see
Related Features, below). The added shearline forces apply to the selected
force distribution method, rigid or flexible.
d) Load Distribution to Shearlines
The
program performs rigid and flexible diaphragm distribution for both case 1 and
case 2 load cases, and uses the largest resulting shearline force as the design
force. This is done before any design or any intra-shearline distribution,
similar to the way it currently chooses the worst of several low-rise wind load
cases.
The
minimum loads are distributed independently for rigid and flexible diaphragms,
creating two separate sets of shearline forces
e) Vertical Force Distribution
For the
all-heights procedure, rigid diaphragms, the program previously gathered the
loads to distribute by taking all the loads on levels above the level being
designed. This is in contrast to the low-rise and seismic procedure that uses
the flexible diaphragm forces on the floor above. These methods are mathematically equivalent.
This was
done because the rigid diaphragm procedure required 75% loads, but the flexible
procedure required 100% loads. As this is no longer the case, for rigid
diaphragms, the program uses flexible diaphragm forces on the floor above for
all load cases.
f) Output
i. Load Table
Previously,
both Case 1 and Case 2 loads were shown only when Case 2 is selected, now they
are shown all the time.
ii. Hold-down Design and Drag Strut Tables
The load
case showing in these tables is now the critical one for design, and can be
different for each shearline. Previously, each entry in the table showed the
case selected in the Design Settings
Note
that the load case is not shown in the Shear Results tables due to space
limitations, so that the hold-down and drag strut tables can be used to infer
which load case was used for shear design.
iii. Log File
In the
torsional analysis section, rigid diaphragm analysis is now be repeated for
Case 1 and Case 2, indicated by e.g.
E->W and N->S WIND DESIGN (CASE 1)
g) Related Features
A number
of related features have also been added, which are explained in more detail
elsewhere in this list. These are
- Case 2 loads are now applied to flexible diaphragm design,
- Inherent building torsions are included for rigid diaphragm design for both Case 1 and Case 2 loads,
- You can override the percent loading and percent eccentricity for Case 2 loads (the above explanation assumes 75% Case 2 loads at 15% eccentricity, but that can be changed).
- Minimum loads have also been added as a separate load case.
- Limitation of Case 2 loads to structures with 3 stories or more.
The
program has implemented the change in intensity for minimum wind pressures in
ASCE 7-10, minimum wind loads from ASCE 27.1.5 and 28.4.4 as a separate,
simultaneous load case, and over-rides of the intensity of minimum pressures
for local design codes.
a) Intensity of Minimum Wind Loads
For ASCE
2005, a minimum wind load of 10 psf was applied to the walls and the projected
roof area. For ASCE 7-10, this has been changed to 16 psf for walls and 8 psf
for roofs. Because of the new 0.6 ASD load factor for winds, this amounts to
virtually the same wall loads, but a reduction in roof loads by ½.
Note
that gable ends are treated as walls, not roofs, despite the fact they are
modelled as part of the roof creation procedure.
b) Minimum Wind Load Over-ride
Certain
local design codes require a different minimum load, for example New York City
requires 20 psf. Therefore, the program now allows you to adjust the intensity
of the minimum load for walls and for roofs, with the defaults being 16 psf and
8 psf. These are input in the Site
Information dialog box, and are recorded in the Site Information output table.
c) Minimum Loads as a Separate Load Case
As
Commentary C27.4.7 states that minimum loads are to be applied “as a separate
load case in addition to the normal load cases..”, the
program now generates minimum loads simultaneously with either
Directional (All Heights) or Envelope (Low-rise) loads and calculates shearline
forces separately for those loads.
i. Previous Procedure
Previously,
a checkbox in the Load Generation input allowed you to generate minimum loads.
The operation was different for All Heights vs. Low-rise loads; for All Heights,
the program would selectively apply the minimum load to building elements that
it determined were not loaded to the minimum for the all-heights procedure; for
Low-rise, the program would generate minimum loads on the structure but not
generate low-rise loads. You had to make separate runs and compare your results
manually.
The
input in the Load Generation box has been eliminated, along with associated
message box warnings.
ii. New Procedure
The
program always creates loads due to the minimum pressure on walls and the
projected roof area. It then distributes loads to the shearlines using each set
of loads, and determines the heaviest loading to use for shearwall design. That
is, the program compares the shearline forces derived from minimum loads to all
four low-rise cases in a particular direction, or two the Case 1 and Case 2 all
heights loads, and chooses the critical force for design.
iii. Plan View
A choice
“Minimum” has been added to the Show…
menu under “Wind Load Case”, enabling you to see the loads and shearline forces
created using Minimum loads. An
equivalent checkbox has been added to the Loads
and Forces settings.
iv. Load Input View
In the
Load Input View, the word Min appears
in the load list for generated minimum loads. It is not possible to designate a
force that you enter manually as minimum.
v. Load and Force Output
In all
the tables that currently have a column for load case word, the word Min has been added for minimum loads,
with an explanation in the legend below:
Wind
Shear Loads
Hold-down
Design
Drag
Strut Forces
The note
regarding the previous minimum load procedure has been removed from the Wind Shear Loads table.
vi. Shear Design Output
The note
that previously appeared saying that you must run minimum loads separately from
normal load cases and compare has been removed.
vii. Log File
Minimum
loads do not appear in the load generation section of the log file, as the log
file output shows intermediate data used to arrive at the pressures used to
generate loads, and minimum loads specify the pressure without the intermediate
data.
In the
torsional analysis section of the log file for rigid diaphragms, the case
showing the calculations for minimum loads is shown by e.g. E->W and N->S WIND DESIGN (MINIMUM
LOADS)
viii. Files from Previous Versions
The
program detects whether a project from a previous version of the program
includes minimum loads, and then prompts you with a recommendation to delete
the loads and regenerate.
5. Envelope (Low-rise) Load Model
ASCE
7 has restored the model of low-rise loading in figure 28.4-1 to have the same
nomenclature and set of load cases that it did with ASCE 7-98 and before, and
that was implemented in the versions of Shearwalls before 2004c , released in
July, 2006. Version 10 restores these load cases and nomenclature.
The
main change to this model is that the MWFRS in the transverse to ridge
direction has 2 separate load cases, Case A and Case B. Preciously what is now
Case A was applied only to the transverse direction and Case B only to the
longitudinal direction. Case A in the
longitudinal direction creates opposing shearline forces that tend to cancel
out and rarely govern when compared to Case A, but this case has been restored
to the program for completeness.
a) End Zone Changes
i. Longitudinal End zone
The
longitudinal load Case B end zone width has been reduced to ‘a” rather than 2a.
‘a’ is defined in Note 9.
ii. Transverse End zone
There is
now an end zone for the load case B on the transverse surface that has been
implemented.
b) Plan View
i. Load Arrows
The
large load arrows in plan view are now shown at an oblique angle which
indicates the low rise wind range for that case.
ii. Show menu
The term
MWFRS Direction is changed to Orientation, and it no longer controls
whether it shows transverse or longitudinal, instead just acts as it does for
all-heights in turning off one direction to reduce clutter.
The Wind Load Case now allows you to choose
between Case A and Case B , whereas previously it was disabled for low rise..
Equivalent
changes have been made in the Loads and Forces settings.
iii. Case A Side, Case B End
A new
option has been added to show the loads for Case A in the longitudinal
direction, and Case B in the transverse direction, as these are the cases that
will ordinarily govern for design. In this case, the program shows exactly what
it did for Version 9, with the load arrows appearing at right angles.
c) Load Input
The load
list now shows A or B under the heading A/B
rather than T or L under T/L
d) Output
In the
following tables, and in the log file output, the Load Case T or L is changed
to A or B
Wind
Shear Loads.
Hold-down
Design
Drag
Strut
The
explanations in the legends have been changed accordingly.
e) Windward Corner Nomenclature
In the
Show menu and in the Hold-down table legend, “Wind Reference Corner” has been
changed to “Windward corner” to agree with current ASCE terminology.
The
program now allows you to optionally implement ASCE 7-10 figure C28.4-2 for
wind loads on hipped roofs. Note that with this model, for both load case A and
load Case B, case A coefficients are used, so that Case A and Case B are
identical in the transverse-to-ridge direction.
a) Setting
An
option in the Load Generation input dialog allows you the choice of using
figure C28.4-2 or treating the end panel as a transverse side panel as Version
9 does.
b) Note 8 Loads
The
loads that are generated due to Note 8 for distances greater than ½ the
horizontal dimension of the building are created for this method.
c) Equal Slope Restriction
The
restriction that hips on opposite ends of the roof must have equal slopes is
dropped for this method.
d) Warning Message
The
warning message that we treat hip ends as side panels does not appear if the
C28.4-2 method is chosen.
7. Over-rides of Case 2 Eccentricity and Load
Percentage
ASCE 7
Commentary C27.4.6 states that the 15% eccentricity and 75% for All Heights
Case 2 loads may not cover all cases, and said for certain buildings, 5%
eccentricity at full loading is more appropriate. Therefore, we now allow you
to control the eccentricity and percent loading to be used, with the default
being 15% and 75%.
a) Input
The
inputs added for this are in the existing are in a new data group called Directional (All heights) Method
i. Load Percentage
In a new
data group called Directional (All
heights) Method there are data
fields called Applied to enter the
percentage of load used, defaulting to 75%, for each building direction.
ii. Eccentricities
The
existing Eccentricity inputs that
previously were for dynamic analysis (flexible structures) only, are now also enabled
for the usual static analysis case. For static analysis, you enter a percentage
of building width; for rigid analysis, and absolute value in feet.
b) Load
Generation
The load
generation process creates Case 1 loads according to the ASCE standard, and
case 2 loads by multiplying the Case 1 magnitudes by the percentage entered.
When shearline forces are created with Case 2 loads, torsional analysis is
applied for both rigid and flexible diaphragms, with an accidental eccentricity
equal to the percentage entered multiplied by the building width for rigid
structures, and the entered eccentricity for flexible structures.
c) Design Results Output
The
eccentricities entered and the percent loading is echoed in the Site
Information section of the Design Results.
d) Log File Output
i. Input Echo
The
eccentricities and load percentage appear in the input echo.
ii. Eccentricity Line
The
proportion of building width B is given on the line showing the actual
eccentricity in each direction.
iii. Design Code Note
The
source of the eccentricity is given in an explanatory note - either entered by user due to C27.4.6 or from Figure
27.4-8 for 15%. This is followed by the percentage of load.
iv. Flexible Torsions Explanation
For
flexible diaphragms, the eccentricities and load percentage also appear in the
explanation at the top of the torsional analysis procedure.
8. Limitation of Case 2 Loads to Three Stories or
More
The
program now implements the Exception to 27.4.6, referring to Appendix D 1.1,
which says that buildings two stories or less do not require Case 2 loads (75%
loading plus 15% moment). On buildings
for which all blocks have 2 levels or less, only Case 1 Directional (All
Heights) loads are generated. These loads are at 100%, with no additional
torsional moment.
ASCE
Commentary C27.3.2 indicates that the 0.00256 constant used in the calculation
of wind pressures in Eqn. 27.3-1 corresponds to average air pressure at sea
level and if sufficient weather data are available a value based on actual air
pressure can be used. Therefore the program now allows you to adjust this value
as follows
a) Input
In the
Site Information dialog, a group box called Mass
Density Constant has been added, with the following data inputs:
i. Altitude
Altitude
of building site in feet defaulting
to 0.
ii. Use … Density
The
following choices for the density used to reference Table C27.3-2. We chose not
to allow minimum density.
Average
Maximum
iii. Density
An edit
box called Ambient air density, with
unit label lb/cu.ft. You can override what is calculated from the
other selections.
iv. Constant
A text
field with the resulting constant that is used in Eqn. 27.3-1 appears, but
cannot be changed.
b) Calculation of Wind Velocity Constant
The
arithmetic in C27.3.2 indicates that the equation 27.3-1 for the velocity
pressure is just the dynamic pressure term in the Bernoulli equation:
q = ½
ρv2,
So the constant which is 0.00256 is at sea level
is calculated as
169 /
162 ρ/g
g = gravitational acceleration = 32.174 ft/s2
ρ =
ambient air density in lbm/ft from Table
C27.3.-2 (lbm = pounds mass). The table
is interpolated for altitudes that are not listed.
The
constant 169 / 162 in this expression comes from ½ * (5200 / 3600)2,
the latter two numbers being conversions from feet to miles and seconds to
hours, respectively, because v is in miles per hour. g is a conversion factor between pounds of mass and pounds of
force. (Note that this g should not be confused with the g that appears in
Bernoulli’s equation in the hydrostatic term ρgz for the gravitational effects on heavy fluids,
which does not apply here).
10. Component and Cladding (C&C) Loads
a) Load Combination Factor
The new
0.6 ASD load combination factor is applied to C&C loads when used for
sheathing strength and nail withdrawal design.
i. Plan View
In
agreement with all other loads shown in plan view, the unfactored C&C load
is shown.
ii. Elevation View
In the
elevation view output, the word “Unfactored” has been added to indicate that
the C&C load shown has not been factored.
iii. C & C Table in Design Results
iv. The loads shown in the C & C table of the
design results have been factored by the 0.6 factor.
b) Windward Pressure (Feature 207)
Shearwalls
needs only the leeward (suction) C&C pressure for both sheathing strength
and nail withdrawal design, because the leeward coefficient in Fig 30.4-1 is
always larger than the windward one for the small areas considered, and
interior pressures are the same in both directions. However, some users were
confused by the discrepancy between their calculations for windward pressures
and the C&C pressures on the screen for a windward load direction shown. Accordingly,
shearwalls now calculates the windward and leeward pressures.
i. Plan View
Shearwalls
now shows both the windward pressure if the displayed wind direction is
directed towards a surface, e.g. for the west face for west to east loads. It
previously showed the leeward (suction) pressure.
ii. Elevation View
Both the
leeward and windward pressures are now shown in elevation view.
iii. Design
The
worst of leeward and windward pressures are used for sheathing design. Only
leeward pressures are used for nail withdrawal. In ordinary circumstances, that
is if loads are generated on all surfaces, leeward pressures are always used
for design.
iv. Reference Height for Buildings Greater Than 60
ft. (Change 125)
For
buildings greater than 60 ft in height, the reference height used for
calculation of windward velocity pressure coefficient Kz is the
actual height at the top the level in question, rather than the mean roof
height. This applies to both external and internal pressures. Note that wood
buildings that tall are rare, and that the reduced C&C load on lower levels
does not tend to govern because of the accumulated shear forces on lower
levels, so this change as little effect.
c) C&C Loads Per Wall Line (Feature 206)
Because
different wall lines can have different reference heights h because they are on
different blocks, but be on the same face of the building in terms of N, S, E,
W directions, the program now assigns separate C&C loads to each wall line.
If the wall line includes walls from more than one block, the highest C&C
load from the blocks is used.
As a
result, C&C loads are shown in plan view on each wall line with exterior
walls. Previously only one C&C load was shown for each building face .
11. Wind Load Generation Inputs – Miscellaneous
Changes
a) Gust Effect Factor
The gust
effect factor is still active only when Dynamic
analysis (flexible buildings) is selected.
i. Location of Input
This
input has been moved into the new data group called Directional (All heights) Method
ii. Default Value
The
default value is 0.85 rather than 1.0.
0.85 is the usual value for static analysis (rigid structures), whereas
1.0 is an arbitrary value.
b) Wind Speed Terminology
Changed
the Site Information input to Basic wind speed, from Wind speed, to conform
with the terminology in 26.5.1. Removed obsolete material in status bar
explanation, and added reference to the wind speed maps, Fig 26.5-1.
c) Default Wind Speed
The
“factory” default wind speed that comes shipped with the program has been
changed from 100 to 130 mph, in accordance with the new wind speed maps
d) Tool Tips for Wind Load Generation Controls
(Bug 2675)
When you
hovered your mouse over the input controls of the Wind Loads group of the generate loads box, small “tool tip”
messages appeared, but they did not appear for the seismic loads controls or
other buttons in the dialog box. The Exclude roof portions.. checkbox mistakenly gave the message for C&C loads.
Messages
have been added for all inputs in this box and the Exclude roof portions
message has been corrected.
12. Wind Load Generation in Design Results Summary
– Miscellaneous Changes
a) Torsional Analysis Note in Shear Results
The note
at the start of the Shear Design section of the Design Results explaining that
torsional analysis according to 28.4-1 Note 5 is not done now differentiates
between the case of 2 stories or less and three stories or more, providing a
different explanation for these two cases.
b) Static Analysis in Site Information Output
If
Dynamic Analysis, Flexible Buildings is not selected, the program outputs Static Analysis (Rigid Buildings). Previously
it did not indicate anything.
c) Gust Effect Factor for Dynamic Analysis ( Bug
2649)
The user
input value for the Gust Effect factor for dynamic analysis is now echoed in
the Site Information table of the Design Results. .
d) Note for
Transverse Wind Loads with Flat Roof (Change 160)
The note
about roof loads not being generated because they are opposite to the wall
loads appeared for flat roofs which have no roof loads. It has been removed for
this case.
13. Wind Load Generation in Log File –
Miscellaneous Changes
a) Topographic Effects in Log File
The
information about topographic effects entered in the site dialog is now echoed
in the log file output.
b) Components and Cladding Method in Header
The design
method for component and cladding loads ASCE
7-10 Ch. 29 Part 1 (h <= 60 ft.) has been added to the header of the log
file wind load generation info section
c) Data Pertaining to All Loads (Change 156)
The
values for Kd and GCpi and the terrain exposure constants
were moved from below the Site Information to be in a new section called Data (all loads) below the list of equations they pertain to, and
have lost their ragged formatting.
d) Equations Section (Change 156)
A line
saying "Equations:" has been added to delineate the equations in
their own section.
e) Asterisked Values Log File for C&C Loads
(Bug 2555)
In the
log file column for start and end, two numbers that aren't the start and end
appeared for C&C loads, followed by one and two asterisks, respectively.
However, no explanation of the asterisks or the values appears. The values were
just a rounded off version of the GCpi and the value of 1.0 that was
not relevant to anything.
These
have been removed and the start and end point of the location on the building
that the C&C load applies to appears instead. Note that if there is a gap
in a shearline, the start and end are the start and ends of the extreme
segments on the wall line, so that the load is not continuous over the range
shown.
f) Wind Speed Terminology
Changed
the Site Information input to Basic wind speed, from Design Wind speed, to
conform with the terminology in 26.5.1.
1. Seismic Load Generation Nomenclature
a) Risk Category
What was
formerly called “Occupancy” has been renamed “Risk Category, in accordance with
the nomenclature change in ASCE 7 2010 vs the 2005 edition. This change is
reflected in the Site Information Input, the Design Results output, and several
places in the Log file output.
b) Importance Factor
In
several places in the Log file output for seismic load generation, and under
the Seismic Information Table, the symbol I for Importance factor has been
changed to Ie for Importance Factor -
Earthquake
2. Diaphragm Force and Drag Strut Force Increase
The
program now calculates the total diaphragm design force Fpx from
equation 12.10-1 in 12.10.1.1 on each floor in each direction. This force is
output to aid you in manually doing diaphragm design calculations (Shearwalls does not model or design
diaphragms), and is the force used for the 25% increase in drag strut forces
required by 12.3.3.4 for irregular structures.
a) Irregularity Input
The Site
Information input that was previously called Irregular Structure, which was used for redundancy factor
calculations, has now been replaced by two settings,
Horizontal irregularity or in-plane vertical
discontinuity irregularity.
Other
vertical irregularity
The
first of these settings is used to trigger the 25% increase in drag strut
forces required by 12.3.3.4. If either
is selected, then the building is considered irregular for redundancy factor
purposes. These inputs are echoed in the Site information output in an
abbreviated form.
b) Shearline Forces for Drag Strut Calculation
If the
irregularity checkbox is checked, and the other conditions of 12.3.3.4 are met
(Seismic Design Category D-F), then the program determines the shearline forces
that are derived from the diaphragm force by multiplying the shearline design forces
that were derived from Vx from 12.8-13 by the ratio between the
diaphragm force Fpx from 12.10-1 and
Vx . The program then uses the worst of the forces derived
from 1.25 Fpx and from Vx
to calculate drag strut forces along the shearline. Note that the
force from 1.25 Fpx will
govern only on the top level of the structure, and in some cases on the level
immediately below, because it does not accumulate from level to level as Vx
does.
c) Diaphragm Force Output
The
diaphragm force Fpx has been added to the Seismic Information table
in both directions and in both levels. This is an unfactored (strength-level)
force.
A note beneath
the table that has been added explaining that story shear does not include
user-applied seismic forces also mentions the same thing about the diaphragm
force.
d) Drag Strut Force Output
When the
seismic design category is C-F, the legend to the Drag Strut table explains
that the shearline force is derived from the greater of Fpx with 25%
irregularity increase and Vx
The
legend also now mentions that the shearline force is factored by the redundancy
factor rho.
3. Amplification of Accidental Torsional Moment
The
program now implements ASCE 7 12.8.4.3, the amplification of accidental
torsional moment, for Seismic Design Categories C-F.
a) Irregularity Detection
As this
is required only for buildings with torsional irregularity, the program now
automatically detects torsional irregularity 1a from table 12.3-1.
On each
level of the building and in each direction the program determines if the
largest of the two end wall storey drifts δmax is greater than1.2 times the average of the
end wall storey drifts δave.
In doing so it takes into account both +ve and –ve accidental
eccentricities, and uses the worst of these to determine the irregularity and
the resulting amplification factor Ax.
b) Calculation of Amplification Factor
If an
irregularity is detected on a particular level and direction, the program
calculates the amplification factor from Eqn 12.8-14.
Ax
= ( δmax / 1.2 δave )2
The
factor is limited to a maximum of 3.0, and is only applied if it is greater
than 1.0.
c) Application of Factor
In the
equation for torsion becomes ,
T = (
CL-CR +/- ae * Ax ) * F,
where CR
= Centre of rigidity, CL - Center of load or mass, F -concentrated force, ae -
accidental eccentricity:
Note
that multiplying both the positive and negative accidental eccentricity by Ax
always results in an increase in shearline force. If the inherent eccentricity
is larger than the accidental eccentricity, it is true that in one direction
the overall torsion is diminished, but that is always the least critical of the
torsions that is rejected by the program. If the accidental eccentricity is
larger than inherent, then both amplified torsions are needed as they are
critical for shearlines to the right and to the left of the centre of
rigidity.
d) Log File Output
If an
amplification factor is applied in a particular direction, then the factor is
output in the torsional analysis section of the log file, and the equations for
torsion T adjusted to show ae multiplied by Ax.
e) Design Summary Output
If an
amplification factor has been applied anywhere in the structure, a note appears
under the Seismic Information table indicating a torsional irregularity was
detected, the Ax factor was applied, and referring you to the log file for more
details.
ASCE
12.8.6 indicates that the design story drift is to be computed at the center of
mass, except for structures in seismic design category C, D, E or F having
torsional irregularity (Horizontal Irregularity 1 in Table 12.3-1), which must
use the largest story drift at the edges of the structure. Furthermore, ASCE
12.3.1.1 indicates that all shearlines must satisfy story drift limitations for
the building to be modelled with flexible diaphragms. These provisions have
been implemented in the Story Drift section of the Design Results output as
follows:
a) Cd and I columns
The
columns for the deflection amplification factor Cd and the
importance factor I have been removed from the table to make room, as they are
not needed for each level. Instead, a note below the table shows the value of Ie
and of Cd in each direction,
and also gives Equation 12.8-15.
b) Center of Mass
New
columns are given showing the location of the center of mass, and the values of
δx and δxe at the
center of mass, calculated by by straight line interpolation of the deflections at the two shearlines
on either side of the center of the mass. A legend entry explains the
calculation.
For
flexible diaphragms, a note is included saying it does not include the
difference in deflections of the diaphragm at the top and bottom of the story,
that is, that portion of the diaphragm between shearlines that deflects
relative to the shearline.
c) Maximum Deflection
If the
design is rigid diaphragm, torsionally irregular and seismic zone C or worse,
use the highest deflection of all shearlines that have exterior walls for the
“max dx” value. Otherwise the max dx is the max of all shearlines as it previously
was for all cases.
d) Failure Messages and Warnings
Different
failure messages appear beneath the table for each of the conditions –
torsionally irregular rigid, other rigid, and flexible diaphragms. In addition,
if centre of mass is used and the centre of mass is within limits, but another
shearline is not, a warning appears.
5. Out-of-plane Wall and Wall Anchorage Forces
The
program now calculates and displays the out-of-plane forces for structural walls
from ASCE 7 12.11.
a) Out-of-plane Force
The
out-of-plane force is calculated using 12.11.1 and the self-weight of the wall
as input in the Load Generation dialog.
b) Wall Anchorage Force
The wall
anchorage force is calculated using Eqn. 12.11-1 in section 12.11.2.1.The
length used for the ka factor in Eqn. 12.11-2 is the shearline
length (including any non-shearwalls and openings or gaps within the line, but
not gaps at between the end of the line and the end of the floor or ceiling
diaphragm).
For
rigid diaphragms, the height factor given in the penultimate paragraph in
12.11.2.1 uses the eave height as roof height z.
c) Elevation view Output
At the
end of a shearline in elevation view,
where C&C loads are shown for wind design, for seismic design the program
shows the factored anchorage and out-of-plane forces.
For
flexible diaphragms, the program shows the out-of-plane and anchorage force at
the top of the wall. For rigid diaphragms, it shows the anchorage force at the
top and bottom of the wall, as these differ due to the height factor. So both
rigid and flexible design is needed to see all of these forces.
You are
now able to specify ρ instead of having the program calculate it, and
the factor has been
removed from the body of the Seismic Information table to the notes below.
a) User Control of Redundancy Factor ρ
(Feature 160)
Because
the calculations for are complex and Shearwalls cannot take into account
detailed structural features, and shearwall design and rigidity-based load
distribution is quite sensitive to changes in the redundancy factor ρ, we have added the capability of
over-riding the program calculations and specifying your own ρ value.
i. Input
To the
building site dialog two combo boxes have been added for entering ρ for
the east-west direction and ρ for the north-south direction; the choices
are Calculated, 1.0 or 1.3.
ii. Design
During
design, if either 1.0 or 1.3 has been selected for ρ, then the selected
value is used, and the building is designed. If you specify that ρ is
calculated, then for the initial design pass, rho is set to 1.0.; after design,
ρ is calculated and if it is 1.3 then the design is redone using a rho of
1.3. This is done independently in both directions.
b) Seismic Information Table Output
The
redundancy factor has been removed from the body of the Seismic Information
table because, since ASCE 7 2005, it no longer varies from level to level.
Instead a small section of text below the table gives
the
factor in each direction,
whether
it was entered by user, automatically calculated, or permitted to be 1.0 for
categories B and C (Change 143)
the
design code clause governing the factor
the
range of seismic design categories for that clause.
If the
factor is 1.3 rather than 1.0, a note says that it applies to shearwall design,
hold-down forces, and drag strut forces, but not to story drift or out-of-plane
forces.
7. Seismic Load Generation Input - Miscellaneous
Changes
a) Seismic Design Category in Site Information
Dialog
The Site
Information dialog now shows a non-editable text box giving the Seismic Design
Category, from A to F. This updates whenever you change an input that affects
the design category – the Site Class, the Risk Category, and the values of Ss
and S1.
In this
way, you do not have to wait until a design is done before knowing the design
category, which can affect other modelling decisions.
b) Reference to 12.8.2 in Maximum Period Message
(Change 147)
The
message about entering a period greater than the maximum now refers to ASCE 7
12.8.2.
8. Seismic Load Generation in Design Results –
Miscellaneous Changes
a) Base Shear Note (Bug 2518)
A note
has been added below the seismic information table explaining that story shear
shown and the diaphragm force shown do not include user-applied seismic loads,
but do include loads derived by user-applied building masses.
b) Output of Procedure Name
The
output of the procedure name in the Site information now gives the Chapter
number in ASCE 7, that is 12.8 for categories B – F, and 11.7 and 1.4 for
Category A. Previously it erroneously stated that the Equivalent Lateral Force
Procedure applied to Category A
c) Building System
The
input for the Building System (Building frame or Bearing wall) was not echoed
in the Site Information output. This has been corrected.
d) Seismic Loads Note
In the
note to the Seismic Loads table, the term reliability/redundancy
has been changed to redundancy. Reliability is a term from the obsolete
UBC code.
e) Table 12.2-1 Note (Change 145)
The
notes and warning messages under the Storey Drift table for one story
structures referred to ASCE 7 Table 12.2-1 instead of 12.12-1. This has been
corrected
f) Equation 12.8-12. Reference (Change 146)
The
legend to the Seismic Information table for weight wx referred to equation ASCE
7 12.8-11 instead of 12.8-12. This has been corrected.
9. Seismic Load Generation in Log File –
Miscellaneous Changes
a) Header
The
header to the section has been reformatted to be consistent with the wind load
header, and gives the procedure used, either ASCE 7-10 12.8 Equivalent Lateral Force Procedure
or ASCE 7-10 11.7 and 1.4 for Category A
b) Distribution of Base Shear Table
The
table showing the distribution of base shear to the building levels has been
expanded to show the values of Cvx in Eqn’s 12.8-11 and 12.8-12, and
the value of Vx in equation 12.8-13.
c) Design Category A Equation
The
Force equation for Seismic Design Category A,
Fx
= 0.01 wx from 1.4-1, has been added to the list of equations in the
seismic load generation section of the log file.
d) Equation for Fj
The
equation for Fj now indicates the design code clause it most closely
can be said to be derived from, 12.8.4.1, in order to have clauses by each
entry for readability.
e) Maximum Ss Note (Change 144)
The note
for maximum Ss value in the log file due to 12.1.8.3 changes "does not
use" to "is not limited by".
f) Spelling Errors
The
letter el is used in place of the number one in the heading to the base shear
table. This has been corrected.
The User Input and Source section now refers
to Site Class F rather than f.
D. Load and Force Distribution
The
program implements the change in ASCE 7 of the ASD wind factor to 0.6 from 1.0;
it retains the 1.0 wind load combination factor for deflection, which is now
the strength-level factor in ASCE 7; it no longer allows input of different
load combination factors than those in ASCE 7, and it shows in the output the
load factors used for deflection design.
a) ASD Wind Load Combination Factor
ASCE 7
and IBC now have an Allowable Stress Design (ASD) wind load factor of 0.6,
rather than the previous 1.0, see ASCE 7 2.4.1. This change is in conjunction
with new wind speed maps with higher wind speeds intended for strength-level
design.
The new
0.6 factor is now applied to forces used for shearwall design, hold-down
selection, and drag strut forces. It is indicated in the program as follows
i. Wind Shear Loads and Forces
Loads as
shown on screen and in Loads tables in output remain unfactored. The shearline
forces are the forces used for shear wall design are factored by 0.6 when the
loads are distributed to the lines.
The 0.6
factor has been added to the load combination shown in the plan view legend.
ii. Beneath the Wind Shear Load table in the
output, a note has been added to indicate that the loads are unfactored and the
0.6 factor is later applied to forces, similar to the note that appears for
seismic loads.
iii. Wind Uplift Loads:
The wind
uplift loads you enter are considered to be unfactored. When creating
hold-downs, the 0.6 factor is applied to the wind uplift component of the
combined hold-down force.
The word
Unfactored has been added to the
description of uplift loads in the plan view legend.
Beneath the Wind Shear Load table in the
output, a note has been added to indicate that the loads are unfactored and the
0.6 factor is later applied to forces, similar to the note that appears for
seismic loads
iv. Hold-down Forces
The wind
shear overturning component of hold-down forces is derived from the shearline
force factored by 0.6. The 0.6 factor is applied to uplift wind loads when
hold-down forces are made. The elevation
view legend now shows the 0.6 factor for uplift component of hold-down forces
instead of 1.0. The hold-down forces for
deflection analysis adjust this to use strength-level factors for the hold-down
displacement component.
In the
hold-down design table, the legend on indicates the wind shear overturning and
uplift force components are factored by 0.6
v. Wind C&C Loads
vi. The loads that appear on the plan view and
elevation view screen are unfactored; those that are used for design and appear
in the Design Results output are factored. The word “unfactored” has been added
to the presentation of these loads in plan view and elevation view.
b) Strength-Level Wind Load Combinations for
Deflection Analysis
The
program continues to apply a 1.0 wind load combination factor for deflection.
This represents a change in that previously the strength-level factor for wind
design was 1.6, and now it is 1.0, so that the program previously applied ASD
combinations for deflection analysis for wind loads, but now applies
strength-level factors.
This
change makes wind design consistent with seismic design, and with the
assumption of strength-level displacements that are to be used when hold-downs
are made.
This
factor is indicated in the program as follows:
i. Shearline Force
The 0.6
ASD shearline force factor is adjusted to the 1.0 strength level factor for deflection analysis. This force is
shown only in the Deflection table of the output. The legend to the table now
indicates the force v is the strength level force, and is the ASD force / 0.6.
ii. Hold-down Forces
The
Uplift Force (P) shown in the Hold-down Displacement table is derived from wind
shear and wind uplift forces factored by 1.0 for strength level analysis. The
legend now indicates that they are strength level forces, but no longer says
they are “unfactored” as there is a dead load factor of 1.2.
c) Opening Files From Previous Versions
Upon
opening files that have generated wind loads created with versions of ASCE 7
prior to 2010, and/or user input loads that were created with version 9 or
before, the program prompts you with an explanation of the wind load changes,
and an opportunity to adjust all your generated loads by a factor of 1.0 / 0.6
or to delete all the loads for future regeneration.
d) Load Combination Factor Design Setting
It is no
longer possible to change the dead load and seismic load combination factors
via the design setting. These factors are mandated by the ASCE 7 and IBC design
standards are not modified by local building codes, so there is no reason for
user control of these values.
e) Load Combinations Output
Despite
the fact that they have been removed as a design setting, for informational
purposes the load combination factors remain in the Design Setting table. This
table now shows the strength-level load combinations used for deflection
analysis alongside the ASD combinations used for shearwall design, whereas
previously only the ASD combinations were shown.
f) Seismic Load Combinations in Hold-down
Displacement Table
The
legend to the Hold-down displacement table no longer says that the load
combinations used are “Unfactored”, as the dead load component does have a
factor of 1.2.
2. Optional Rigid and Flexible Design Methods
ASCE-7 10
has provided less restrictive conditions for which flexible diaphragm
assumptions can be made for seismic design, such that any light frame
construction without concrete topping on the diaphragm can be idealised as
flexible, so long as each shearline complies with storey drift limitations in
12.2-1 (which are ordinarily required to be met only at the center of mass of
the structure). For this reason, and in order to speed up processing time for
complex structures, Shearwalls now allows you to choose whether to design for
rigid diaphragms, flexible diaphragms, or both.
a) Input
A data
group called Diaphragm flexibility has been added, with the options Rigid
analysis and Flexible analysis. You can select one or both of these, but cannot
leave both unchecked.
They are both checked by default, and are
saved with the project file.
b) Flexible Only
When
only diaphragms are chosen, the program does flexible diaphragm force
distribution and shearwall design using these forces. Neither rigid
distribution or design is performed, saving considerable processing time.
c) Rigid Only
When
only rigid diaphragms are chosen, the program first does flexible distribution
(but not shearwall design), then rigid distribution and design. Flexible
distribution is needed to provide the upper level forces used for rigid
diaphragm analysis of multi-storey structures. Flexible load distribution is
much less costly in terms of processing time than shearwall design, especially
when deflections are used to determine shearwall stiffness.
d) Initial Walls for Rigid Diaphragm Rigidities
Previously,
the program used the walls designed for flexible diaphragms to get the
rigidities to distribute loads to the shearlines for the initial iteration of
the rigid diaphragm procedure. This is no longer done, and the length of each
shearline is used as the starting rigidity for the line. Although this was done
to eliminate the need for flexible diaphragm design prior to rigid design, the
change has been made even the flexible method is chosen along with the rigid
method.
Through
experimentation, we determined that the rigidities estimated at via shearwall
length the provided a better starting point for the rigid diaphragm procedure
than the walls designed for the flexible method, because they are not as
influenced by the force distribution using the flexible procedure. The flexible
procedure in general is quite different than the rigid procedure and a starting
point that is often too far removed from the eventual rigid distribution.
3. Inherent Eccentricities for Rigid Diaphragm
Wind Design
Previously,
the program did not include the inherent torsions due to the moment between the
center of wind loading and center of rigidity, as this was not explicitly
specified in torsional load cases that are now in ASCE Fig. 27.4-8 for the All
Heights method. However Commentary C27.4.6 says that
the torsional load to
be added for Case 2 is due to non-uniform wind loading, not the eccentricities
in the loading due to the geometry of the structure. Discussion with ASCE
confirmed that for rigid diaphragms, it is the intention to include inherent
torsion due to building geometry to both Case 1 and Case 2.
a) Rigid Diaphragm Torsional Analysis
For the
torsional analysis for rigid diaphragms, using the terminology in the log file
where F is total force, T is total torsional force, CL is center of load, CR is
centre of rigidity, and B is building width:
i. Case 1
Previously
for Case 1, Shearwalls calculated only direct forces Fdi (using the
terminology in the log file). Now Shearwalls calculates a torsional force Fti
based on (CL-CR) * F. Note that this creates a torsional force in just one
direction, that is, T+ = T-.
ii. Case 2
Previously
for Case 2, Shearwalls calculated only direct forces plus torsional forces
based on +/- 0.15B * F. Now Shearwalls includes the inherent torsion, for a
torsional force based on (CL-CR) * F +/- 0.15B *F .
This is
based on the usual eccentricity of 15% given in Figure 27.4-8, this can now be
overridden with another value.
b) Log File Output
i. Case 1
The line
giving the building width has been removed as this does not apply to Case 1,
which does not have accidental eccentricity. A line has been added saying the
accidental eccentricity is zero, giving the reference 27.4-8.
A line
has been added giving the inherent eccentricity, and the calculation for
torsions is given in place of the note that said they were zero due to ASCE
7-05 Fig. 6-9.
ii. Case 2
A line
has been added giving the torsional eccentricity, and the equation for the
torsions given has been appropriately modified.
4. Seismic Torsions when Low Rise Wind Method
Selected ( Bug 2656)
When you
selected low rise wind loads, the seismic rigid diaphragm torsions were set to
zero in the rigid diaphragm distribution method, so there was no additional
torsional component to seismic shearline forces for rigid diaphragms, and the
direct forces only were used. When the
all heights wind load procedure was selected, the seismic torsions were
correct. This has been corrected and seismic rigid diaphragm torsions are
always calculated.
5. Flexible Diaphragm Forces for All Heights Case
2 Loads
ASCE 7
Commentary C 27.4.6 says that the torsional load cases are due to non-uniform
wind loading, which is applicable to flexible diaphragm buildings as well as
rigid diaphragms. Discussions with ASCE confirmed that the intention was to
apply Case 2 loading to flexible diaphragm design. Sizer now includes Case 2 loads and torsional
moments for flexible diaphragm design.
a) Calculation Procedure
Noting
that the direct (non-torsional) component of the shearline force should be that
determined by tributary area distribution for flexible diaphragm, this can be
achieved by setting the rigidities K to the flexible diaphragm shearline force,
seeing that
Fdi
= F * Ki / Σ Ki ,
using
the notation in the Log file, F being the total force. In that case, the center
of mass CM = Center of rigidity CR, and we are including just the
accidental eccentricity ea and not the eccentricity of the
structure or loads. We also do not consider the torsional moment J in the other
direction, as none of the loads are in the other direction. The
torsional component on each line is then
Fti
= T * Ki * di / (Jx)
where di
is the distance of the shearline from the centre of load and
Jx
= Σ Ki * di 2 ; T = F * ea
Shearlines
already heavily loaded get higher contributions of accidental torsion, rather
than those that are stiffer as in the case of rigid analysis.
b) Verification of Calculation Procedure
For a
simple case of a uniform load on a rectangular building, adding a certain
percentage of torsional eccentricity will add that percentage of total force on
the structure. For more complicated situations, the amount of force will vary
due to the effect of the moment arms of the shearline locations.
To show
that for this simple case, adding 15% eccentricity increases total force by 15%,
consider a 40 ft wide building with 100 lb/ft force on the diaphragm.
F = 4000 lb;
Fd1 = Fd2
= 2000 lb;
K1 = K2
= 2000 lb;
ea = 6 ft;
di
= 20 ft;
T
= 24,000 lb-ft;
J =
1,600,000 lb-ft2
Ft1 = Ft2 = 24,000 lb-ft x 2000 lb x 20 ft / 2000 kN-m2 = 600 lb
= 15% F
c) Forces Analysed
In
contrast to the Rigid Diaphragm section of the log file, factored shearline
forces rather than unfactored loads are analysed, and they are the forces on
the level being analysed only, being accumulated with upper level shearline
forces later. The rigid diaphragm analysis includes loads and/or forces from
upper levels.
A note
has been added to the Log file output explaining this.
d) Log File Output
The
title of the entire section of the log file for torsional analysis has been
changed from “RIGID DIAPHRAGM ANALYSIS” to “TORSIONAL ANALYSIS” , in
recognition that some of the output now pertains to flexible analysis. A
section is added at the top of the results called, FLEXIBLE DIAPHRAGM WIND
DESIGN. The assumptions given in section a), above, are shown first, and then
the results are given as they are for rigid diaphragm analysis. The source of
the accidental eccntricity is given as ASCE 7 Fig. 27.4-8, Case 2.
The note
appears saying that only loads on the current level are analysed, and
accumulation with forces from the level above is done later.
e) Eccentricity and Loading Over-rides
The over-rides
of the 15% eccentricity and 75% loading that you can enter in the Site Dialog apply
to flexible diaphragms as well as rigid.
f) Flexible Structures
The
absolute eccentricity used for flexible structures that require dynamic
analysis applies to flexible diaphragms as well as rigid ( as opposed to the
usual percentage eccentricity for rigid structures.).
g) Adding a Direct Shearline Force
Previously,
if you added a direct shearline force in the Add Load dialog with Both
selected, and Case 2 selected in the settings, the program created a flexible
force at 100% and a rigid at 75% of the value entered. If only rigid or only flexible was selected
the force would be created at 100%..
Because
Case 2 loads now apply to both rigid and flexible diaphragms, the two forces at
75% and 100% are always created, regardless of whether both, rigid, or flexible
forces are being made. This is done only
for buildings greater then 2 stories high.
h) Low Rise Torsions Note
Above
the Shear Results table, the note about the torsional load cases for low rise
loads required by 28.4-1 Note 5 now appears for flexible structures more than 2
stories high, but in a modified form saying these forces cannot govern for
flexible diaphragms.
6. Hold-down Forces Under Gable Ends
The
program now allows you to choose whether the longer moment arm to the sloping
roof, or the moment arm to the ceiling, is used for upper level hold-down
calculations at the gable end. We also fixed a problem with the calculation of
the longer moment arm when there were openings beneath a gable end.
a) Hold-down Moment Arm at Gable End
Starting
with version 9.2, the program calculated the hold-down forces at gable ends by
using the average height of the wall extending to the roof at gable ends for
the overturning moment arm (see Shearwalls Help topic Hold-down Forces for an explanation). Part of the motivation for this was NDS
14.3.1.1 (2), which said this height should be used as the shearwall height,
however, this clause has been removed along with all other NDS clauses.
Some users believe that the ceiling acts as a diaphragm at gable ends, even
distributing the load from the roof to the shearwalls. For this reason, we have
enabled you to model the building such that the diaphragm height at the gable
end is the height of the wall to the low point of the eave.
i. Input
In the
Block input of the Structure Input View, a checkbox has been added saying:
Ceiling
acts as upper level diaphragm
This
checkbox is unchecked by default. When checked, the roof associated with that
bloc is considered to have a ceiling diaphragm that transmits all of the
lateral force to the shearlines.
ii. Hold-down design
When
calculating hold-down forces, if a wall has a roof above it from a block that
has a ceiling that acts as a diaphragm, the moment arm used in the calculation
is the wall height as entered by the user, plus the ceiling height if there is
one if the Hold-down setting to include the floor/ceiling is checked.
b) Hold-down Forces at Openings under Gable End
(Bug 2650)
The
hold-down force calculated for each segment between openings at a gable end was
using the average height of the gable end at the first segment in the direction
of force as the moment arm. It now uses the average height of the gable end at
the segment in question.
7. Torsional Analysis in Log File
Significant
new information and reformatting of existing information for readability, as
well as corrections to inaccuracies, have been made in the torsional analysis
section of the log file.
a) Reformatting
Blank
lines and header bars have been inserted in the file to delineate sections for
readability.
b) Unfactored Forces
A note
has been added under the Rigid Diaphragm title explaining that the forces shown
are unfactored.
c) Vertical Accumulation of Rigid Diaphragm Forces
A note
has been added to the log file explaining that for rigid diaphragms, that loads
on the current level plus unfactored forces from the levels above are used in
the rigid diaphragm analysis, to avoid compounding torsional effect.
d) Building Dimension B
The
building dimension perpendicular to load for torsional analysis of ASCE wind
loading in the log file now uses the symbol B instead of D in conformance with
ASCE 7 27.4-8
e) Inherent Eccentricity
In the
Log file, the phrase “Torsional Eccentricity” referring to the eccentricity of
the building structure has been changed to “Inherent Eccentricity” in
conformance with the ASCE nomenclature from 12.8.4.1. Although this is from the
seismic design section, it has been applied to both wind and seismic torsional
calculation output in the log file.
f) Seismic Force Direction Identifier
For
seismic forces in the east west direction, the program uses the subscript x
when it should use y for eccentricity and centre of rigidity.
g) Wind Load Accidental Eccentricity Line
For all
heights wind design, line giving the accidental eccentricity was unnecessarily
repeated and in an place inconsistent
with other output
h) Seismic
Load Accidental Eccentricity Line
The line
giving the “torsional” (now “Inherent”) eccentricity was missing for seismic
design.
i) Negative Sign in Torsion Equation
For wind
loads, the equations for torsion due to the negative accidental eccentricity
had a negative sign in front of the force F, i.e. T- = - F *(etx - eax). It is not correct and has been removed.
j) Rigid vs. Flexible structure Accidental
eccentricity
The log
file now differentiates between flexible and rigid structures (dynamic vs
static analysis) for accidental eccentricity output. Previously it was
outputting the rigid structure accidental eccentricity for flexible structures
instead of the eccentricity you input in the Site Dialog.
8. Load Distribution Output – Miscellaneous
Changes
a) Minimum Lateral Forces
ASCE 7
1.4.3 requires that the structure be analysed for lateral forces comprising 1%
of the dead load weight of each level. This is equivalent to the force required
for seismic forces for Design Category A.
If seismic design is not performed, a note now
appears below the Shear Design table suggesting seismic design for category A
if you want to check for these forces. However, in most cases they will be much
less than the minimum wind load requirements.
b) Rigidities Used for Shearline Forces Displayed
for Load Cases
When the
Shearwall Deflection method in the Design Settings is used as the method to
distribute loads to shearlines for the rigid diaphragms, the rigidities used
are those from calculated using the critical design case of all low-rise load
cases or the all heights Case 1 or Case 2 loads, or for minimum loads. This has no effect on the ultimate shearwall
design, but might cause a slight discrepancy between the loads shown on the
screen and the forces created. For this reason a note has been added to the plan
view legend and to the Torsional
Analysis- Rigid Diaphragms section of the log file explaining that the
rigidities used for all wind load cases are derived from the shearline force
due to the critical case.
c) Drag Strut Forces Table Legend
In the
drag strut force table legend,
- The line explaining the arrows has been indented to emphasize that it pertains to the shearline force explained above,
- The sentence about the factoring of the force has been placed on a new line and also indented.
- The phrasing “load due to force…” has been changed to “due to shearline force…
-
The non-word "dragstrut” has been changed to drag strut.
1. Highlight of Failing Walls (Feature 75)
If
a wall failed design for the design case ( wind, seismic, rigid, flexible)
shown on the screen, then the failing wall appears in red. The colour for a
selected wall, which used to be red, is now orange.
A
note at the bottom of the screen indicates that orange is for selected walls
and red for failing walls. It also indicates the design case being shown on the
screen.
2. 19.2” Stud Spacing for Unblocked Factor
(Feature 173)
The
program now allows input of 19.2” stud spacing, corresponding to 1/5th
of the length of a standard sheet of plywood. When 19.2” is selected, the
program uses the unblocked factor in SDPWS Table 4.3.3.2 for maximum 20”.
3. Accept Design (Feature 153)
The
other WoodWorks programs, Connections and Sizer, allow you to transfer the
design results from a successful design back to the input fields, replacing
unknown values on those fields. This allows you to experiment with and tweak
your design, for example to use fewer different types of materials at the
expense of optimal strength in some areas.
This
ability has now been added to the Shearwalls– you can transfer the design
results for all walls in the structure from one of the four design cases –
combinations of Rigid or Flexible Diaphragm, and Wind or Seismic.
a) Design Case Menu
A sub-menu
now appears in the Action menu called
Accept Design. When dropped down, it
gives the choice of the four design cases for which to accept design.
If one
of the Design Cases is selected in the Accept
Design Menu, loads from that design case is shown on the screen. However,
this is not reciprocal, if you select another design case via the Show menu,
the Accept Design case does not change. In this way, you can always check the
design case that was used to accept the design.
b) Accept Design Command
The
Accept Design command is invoked either from the Accept Design submenu, or via
a button at the far right of the main program toolbar.
c) Re-running Design
When you
rerun design after Accepting design, the program may fail for other design
cases than the one accepted, because the unknown values have been replaced by
ones strong enough for that design case but not for others. If that is the
case, you can reset some parameters to unknown, then re-run design and then
select the critical case for “Accept Design”.
After a few iterations of this procedure, you can achieve a design that
satisfies all design cases .
d) Non-Shearwalls
Non-shearwalls
are updated only if they were designed for C&C wind loading.
4. Update of Unknown Nail Spacing Input (Bug 2667)
When Both Sides Same is selected, the edge
spacing did not include the Unknown
option, and this persisted for both exterior and interior side when the
checkbox was deselected. This has been corrected, and Unknown is again allowed when both sides are the same.
a) Height to Width Factor Legend in Shear Results
Table
The
legend to the shear results table for the height to width factor refers to
SDPWS Table 4.3.4 notes 2 and 3, when it should be 1 and 3. This has been
corrected.
b) Hold-down Design Table Legend (Change 149)
Design
code references for wind load cases have been added to the legend.
c) Hold-down Design Table Note
The note
about irregularities under the Hold-down Design table now comes before any
warnings and is not in red if warnings are output.
d) Wind Load Cases in Seismic Drag Strut
Table
References
to wind load cases have been removed from the legend to the Drag Strut table
for seismic design.
e) IBC References (Change 148)
Obsolete
references to IBC design code clauses were removed from table notes about shear
increases for certain spacings and nailing patterns in the Materials table.
F. Building Model and Program Operation
1. Import of Bitmap and PDF Versions of CAD Files
(Feature 126)
Previously,
the program allowed input only of Windows Metafile (.wmf) or Enhanced Metafile
(.emf) file formats for CAD drawings to use as a template to draw your
structure. Now, the program allows you to input bitmap (bmp) and portable
document format (pdf) files. The program converts the pdf to a bitmap before
drawing it.
a) Input
The CAD Import Wizard for importing of the
CAD drawings has been updated to allow the following file types
Metafiles
(*.wmf, *.emf)
Bitmaps (*..bmp)
PDF
(*.pdf)
b) Operation
The
operation of the program is the same for bitmap files and pdf files converted
to bitmaps as it is for the metafiles the program was previously restricted to.
2. Multiple Extend Upwards (Feature 193)
The
program allows you to extend your walls upwards in stages, that is, extend
walls up through a more limited number of levels than to the top of the
building. However, in order to maintain a closed envelope, you must always
extend the walls through at least one level and cannot build a level from
scratch.
For
example, for a five storey structure, you can make a floor plan, extend to
floor 2, then be on floor 3, make a floor plan, extend only to floor 3 (that
is, not at all) , then make another floor plan, and extend it from level 4 to
5. Unlike the current operation, the
level indicator in the data bar is active during this process to allow you to
do this.
a) Level Inputs
Two
inputs, one to show the level that you are on and one to show the level that
you are copying it up to, that is the range of levels. The levels are
called Current level and Extend to. The Current Level input is always disabled and is there to show you the
range. Once the process is complete, it becomes enabled to select levels and Extend to disappears.
b) Operation
If you
choose an intermediate storey, or don’ extend at all by selecting the same
storey, then press extend, the program then
- extends to the level selected,
- creates a new floor plan from the blocks for the next unextended level,
- Sets the current level to the next unextended level
- Sets the in Extend to the highest level,
- outputs a prompt explaining how to proceed
If you
extend to a level that is one below the highest level, the program in fact
extends to the highest level and copies the next-to-highest level to that
level.
c) Undo and
Redo
The Undo and Redo commands are active during this process and allow you to go
back and try again if you have made a mistake.
3. Standard Wall Copy (Feature 178)
Previously,
to create a copy of a Standard Wall was done in a roundabout way that not all
users were aware of. ( by pressing Add, then selecting from a list of Standard
walls). To make it more evident, we
added a Copy button to allow you to copy an existing Standard wall. You must
make at least one change to this standard wall before it can be saved.
The
old way of copying a Standard wall still exists alongside the new one for those
users who are more comfortable with it.
4. Adding Openings over CAD Import (Feature 150)
As it was
difficult to see openings on imported CAD drawings as the solid shearwalls in
plan view obscured them, the drawing for the openings action when CAD drawing
is showing has been modified to allow you to see openings. Segmented shearwalls
are transparent with diagonal lines. Perforated walls have hatches and the
non-shearwall is blank as before. If there is no CAD import showing, then
shearwalls are shown in solid colour as before
5. Graphical Selection of Openings (Feature 23)
Previously,
and opening could only be selected via a drop list in the Opening Input form.
Now in the Openings action of Plan View, if you select anywhere within
the thickness of the wall over the extent of any of the openings, then the
opening selected is the one available for editing in the input form.
6. Log File Button (Change 120)
A button
has been added to the main program tool bar to invoke the log file, and to
toggle the log file viewer on and off. The log file button has been removed
from the toolbars attached to the windows for Plan, Results, and Elevation
views.
7. Moving Wall Lines with User Applied Forces (Bug
2676)
Starting
with version 9.1 of the program, moving a wall that is on a shearline with a
directly applied shearline force caused the program to crash. This has been
corrected.
8. Non-wood-panel Stud Spacing Restriction when
Non-Wood-Panels Excluded (Bug 2676)*
For walls
with gypsum on one side and structural wood sheathing on the other, if you
selected to ignore non-wood-panel contribution when combined with wood in the
Design Settings, the program did not allow stud spacing values associated
solely with the wood side of the shearwall. Instead it restricted it to
16" for the gypsum materials that have that restriction. This has been
corrected, and if this setting is checked for both wind and seismic design, the
program allows all stud spacing values.
9. Online SDPWS Edition (Change 158)
The
online help menu item still said SDPWS 2005 even though it had updated to SDPWS
2008 for version 9. This has been corrected.
The
following miscellaneous changes to the output were not associated with features
listed under the major categories in the rest of this list.
a) Default Design Results View (Change 155)
When the
Design Results button is pressed, the default view is now 'Preview" which
shows a full page of design results, rather than "Wide View”, which fills
the horizontal extent of the window, usually zooming in on the top part of the
page.
b) Blank Page in Output (Change 157)
The
blank page that was print out at the end of the Design Results has been removed
c) Log File Header
An
overall header has been added to the log file identifying it as the WoodWorks
Shearwalls Log file and giving the file name and design code editions employed.
d) Wind Shear Load Table Legend (Change 149)
The
legend to the Wind Shear Load table has been reformatted to appear on separate
lines for readability. Explanation for low-rise windward corner added, along
with design code references.
Shearwalls 9.3 –
March 18, 2012 – Design Office 9, Service Release 3
Refer
also to the changes listed for Shearwalls 9.21, 9.22, and 9.25 to view all the changes since the last version
released to the general public.
1. Crash due to Combination of Minimum Wind Loads
and Note 8 Low-rise Loads (Bug 2642)
Shearwalls
would sometimes crash when the following conditions hold:
The
checkbox in Load Generation dialog indicating that minimum wind loads will be
applied is checked
The
building is dimensioned such that loads that are generated due to Note 8 of Fig
28.4-1
These
loads are greater than the minimum wind loads
This
has been corrected.
2. All-heights Coefficients for Walls Extending
Between Blocks (Bug 2473)
When
a building is made from multiple intersecting blocks, the program creates two
walls along one of the sides of an "L", but only one wall along the
side of another. The two walls are assigned to different blocks for wind load
creation, but one the one wall extending between two blocks and until now was
assigned to only one block for wind load generation. When this occurs you have
no way of splitting the long wall up and manually assigning different blocks to
the separate walls. This also occurs when you manually joined walls from
separate blocks.
This
could create incorrect wind loads for blocks with radically different
height-to-width ratios, for example, that a wall extends from a one-storey
block to high one with several stories. It has been corrected and the program
internally splits the wall up and assigns the co-efficients from the correct
blocks to the walls.
Refer
to an explanation in the on-line Help under Canadian wind load procedures, for
a picture and more details.
3. Low Rise Wind Loads Due to Note 8 for Positive
Cp Coefficients (Bug 2550)
Low-rise
wind loads due to Note 8 of ASCE 7 05 Figure 6-10 (now Fig. 28.4-1), that
specifies zone 3 loads on a portion of a
zone 2 windward roof, were being generated for high angles with positive Zone 2
co-efficient GCpf, when they should be limited to low angles with
negative GCpf,. The resulting zone 3 loads have a negative
coefficient that combined with the loads with a positive zone 2 coefficient to
reduce the total load on the roof, creating non-conservative wind loading. This
has been corrected
4. Base Shear due to Manual Building Masses on
North-South Lines (Bug 2518)
When
a building mass is manually added to a North-south shearline, the seismic load
from the resulting mass did not contribute to base shear on the structure,
creating lower-than-expected forces distributed to the building levels. However, the seismic load from the building
mass is created, using the base shear computed without the contribution of that
load. Furthermore, when any seismic load is entered manually, it is not
included in the base shear to be distributed to the rest of the building. This
is not incorrect, but has been made more evident to the user via a note beneath
the seismic information table and in the log file.
Load
and Force Distribution and Engineering Design
5. Directionality of Uplift Wind Loads (Bug 2638)
a) Blank Input for Wind Uplift Force Direction
Starting
with version 9.2, we allow the wind uplift forces to be entered for each wind
direction separately, but by default, when an uplift load was selected, nothing
appeared in the wind direction box. If you proceeded to enter the loads without
selecting a direction, or both directions, then the wind uplift did not get
included in the combined hold-down forces, and the separate wind uplift
component of the hold-down force that was shown in elevation view and in the
output report was unreliable.
In
addition, a load entered with blank direction showed up as blank in the Load
Input dialog edit field, E->W in
the load list, and Both directions in
the load list in the output report. In fact it acted as none of these
The
default showing in this box is now “Both Ways”, and it is never allowed to be
blank.
b) Display of Uplift Loads Entered in Both
Directions
If a
selection was made for the wind direction before adding the load, the combined
hold-down forces were correct; however the uplift component appeared in
elevation view for both directions, when it shouldn’t have.
Different
loads entered west to east and east to west (the usual case) were shown
superimposed and thus garbled in plan view and in elevation view, along with
the uplift components of the hold-downs.
These
problems have been corrected.
c) Editing Wind Uplift Loads
The
following problems in the Load Input
screen used for editing existing loads were corrected:
All
loads showed up in the load list as E->W, even if they were W-> E or Both
Ways.
An
E->W load selected showed the direction in the edit box as blank.
6. Accumulation of Direct Shearline Force for
Seismic Design (Bug 2630)
Starting
with Shearwalls version 9, when a seismic direct shearline force was applied to
a shearline, the program did not include that force in the rigid diaphragm
design shear. The direct forces did show up in both plan view and elevation
view, but not accumulated with forces on the line from the generated loads, so
the numbers overlap. This has been corrected and the seismic direct shearline
forces are once again included in the design shear force.
7. Nonsense Hold-down Values at Gable End of
Monoslope Roof (Bug 2509)
When
there is a monoslope roof, the hold-down calculations at the gable end yielded
nonsense values indicative of a divide-by-zero situation. These hold-down
forces appeared in all output and were used in the design of hold-downs at
these locations. This has been corrected.
8. Shear Deflection for Custom Sheathing
Thicknesses (Bug 2585)
If you
type in a sheathing thickness rather than a standard one, the shear deflection
was set to zero. This has been corrected and the program now uses the
deflection for the next smallest sheathing
1. Distribution Method for Seismic Direct Shear
Forces (Bug 2632)
Starting
with version 9.2, the Distribution Method
control in the Load Create and Load Edit dialog boxes was disabled and showing Both when entering or editing manually
entered seismic direct shear forces. This has been corrected and you can again
distinguish between rigid and flexible distribution methods when adding a
direct shearline force.
2. Standard Wall Relative Rigidity (Bug 2522)
The
"Relative Rigidity" input for Standard walls was not reflected in the
individual walls’ relative rigidity. The program now considers relative
rigidity field when comparing walls to see if they match standard walls.
3. Bolt Diameter Input in Hold-down Database for
Decimal Imperial Formatting (Bug 2517)
When the Thickness Imperial formatting setting is
set to Decimal, then the list of bolt shaft diameters in the hold-down database
input shows nonsensical values like “1/1”.
If you select one of these, or attempt to enter a value like .45, the
program converted it to 0, 1, or a nonsense value the next time the box is
opened.
This has been
corrected.
4. Hold-down Database Message (Change 116)
The
message indicating that one hold-down had to be completed before another
selection had a grammar error.
5. Apply Load Change Message (Change 119)
After
first entering the Load Input view, changing loads prompted you to apply
changes when none had been made. This has been corrected
6. Seismic Load Generation Input Typos (Change
121)
The
spelling of Self-weights has been
corrected from Self Weights. The
“Generate building masses first…" section title has been extended to fit
the ellipses.
7. Arrange Icons Menu Item (Change 129)
The Arrange Icons menu item was removed from
the Windows menu as it was obsolete
and had no function.
1. C&C Design Table in the Results Output
a) Nail
Withdrawal Design Ratio (Bug 2637)
The
design ratio in the Design Results output for nail withdrawal showed the end
zone ratio for both end zones and interior zones. It now shows the correct
ratios.
This
problem did not affect design, as the end zone ratio is used for nail design.
b) Precision of Imperial Nail Withdrawal Values
(Change 130)
The
number of digits precision for Imperial nail withdrawal force and capacity has
been changed from whole pounds to 10ths of a pound.
2. Segment Shear Value in Deflection Table when
Both Sides Same (Bug 2584)
When
there is the same sheathing on both sides of the shearwall, the v value
reported in the deflection table is the shear going into just one of the sides,
so it is in fact ½ the total shear applied to the segment. The resulting deflections calculated are
correct; however the program was showing a misleading shear value. The program
now shows the total shear going into the segment in this case.
3. ASD Typo in Hold-down Displacement Table
(Change 118)
In the
hold-down displacement table, it now says ASD, not ADS, when referring to load
combinations
1. Getting Started Steps (Change 122)
The Getting Started dialog has been updated
to reflect the current state of the program. The text shown for Roofs and Generate Loads has been changed and a new step, Step 14, Log File Output, has been added.
2. Back-up Files (Change 123, Feature 203)
The
program now saves two files to the Windows 7 folder C:\Users\[username]\AppData\Local\WoodWorks\CWC\USA\9
– BackupPre.wsw and
BackupPost.wsw. The first of these saves a project file immediately before
design or load generation, the second saves the file after design or load
generation.
These
files are accessed in the following situations
if an unsaved file is lost after a successful
design or load generation is made, for example by an automatic system reboot.
Either file can be used for this.
The
file BackupPre is used to record the state of the program before
design/generation, so that if a fatal error occurs during one of these
processes, you will have a file to send WoodWorks technical support for
diagnosis. In most cases, this file cannot be used to continue work, as the
error will likely occur again on the next design.
The
file BackupPost is used to continue work if an error occurs during design or
load generation, or at any other time. It will return you the state you were in
when the last successful design or generation occurred. Then you can try to
remake the changes you made to your structure, and it is possible the error
will not re-occur. If it does, contact Woodworks Technical support and they
will try to diagnose the problem and find a work-around.
The
folder that these files are saved to in Windows XP is C:\Documents and Settings\[username]\Local Settings\Application
Data\WoodWorks\CWC\USA\9\.
Shearwalls 9.25 - July 17, 2012
This
version released as a hot fix directly to the user(s) with the following
problem:
3. Failure to Open a Project File (Bug
2088)
Periodically
the program issued an "Unexpected file format" or "WoodWorks has
stopped working message" when opening a project file. When this occurred the file could not be used and if there was no backup
file, then the project had to be reconstructed. This has been corrected.
Shearwalls 9.22 - July 11, 2012
This
version released as a hot fix directly to the user(s) with the following
problem:
1. Crash for Walls Spanning Multiple
Blocks at Gable End (Bug 2510)
When
all of the following criteria are met
A
wall is directly under a gable end
The
wall spans more than 1 block
The
last block in the block list doesn't have any sides that are collinear with the
wall
The
program crashed when performing load and force distribution. This occurred
regardless of whether there are actually any loads on the structure. This sometimes happened when loading
a file and the program proceeds to the load view stage.
Shearwalls 9.21 – July 17 2012
This
version released as a hot fix directly to the user(s) with the following
problem:
1. Shearwall Forces in Shear Results
for Equal Rigidities (Bug 2502)
When
there are openings or non full height sheathing on a shearline and the forces
distributed to the wall segments use the "Equal Rigidities” setting, or
equivalently, the distribution to wall segments setting is not based on
rigidity, then the total force on a wall segment V reported in the Shear
results table is incorrectly based on the total length of the wall rather than
the full height sheathing. The forces shown are thus heavier than expected, and
they do not add up to the total force on the shearline, which is reported
correctly.
This
affects output only; the incorrect forces are not used for design or for
collector force calculations and the correct segment forces appear in elevation
view.
Shearwalls 9.2 -
June 1, 2012 – Design Office 9, Service Release 2
1. Wall Height at Gable Ends for Hold-down Force
Calculation (Bug 2465)
In
order to include the portion of an end wall that is beneath a gable end as part
of a shearwall, for the purpose of hold-down force calculations, the program
now calculates the wall height at a gable end as being the distance from the
base of the wall to the height of the sloping roof at the end of a wall
segment.
The
average of the heights at both ends of the segment under a gable end is used as
the moment arm h in the hold-down force calculation R = vh, where R is the
hold-down force and v is the shear per unit foot directed horizontally.
Previously the height of the upper level was used as the wall height. Refer to
the Shearwalls Help topic Hold-down
Forces for further explanation.
2. Creation of
Wall Groups due to Hold-down Data (Bug 2323)
The
program created wall design groups based on hold-down information such as
"number of brackets”, hold-down type, and number of end studs. It no
longer does so for the following reasons:
-
The
Sheathing and Framing Materials
output does not show these values, so there was no evident difference between
wall groups.
-
These
parameters do not affect design of the wall, just deflection
-
These
parameters differ from other wall group parameters in that they can be
different for different walls on the line when “dissimilar materials” are not
allowed. Therefore a line would have two groups designed for it, and only one
of these was used for design.
-
The default hold-down configuration is to have
single bracket on first level and double on others, so by default wall 2 wall
groups were made even if all materials are the same.
3. Extraneous Message when Running a Design (Bug
2439)
In some
rare instances, when running a design you get an inaccurate message saying that due to a change in the structure,
the last design is no longer valid, and asking you to design again. If you
choose to design again, the design proceeds without a problem. This problem has
been corrected.
1. Wind Uplift Load Directionality (Feature 115)
The
program now allows you to specify the direction for wind uplift loads, that is,
the lateral direction of wind force with which the uplift load is associated.
Therefore you can enter uplift loads that correspond to the uplift coefficients
for the windward and the leeward surfaces in NBCC Figure I-7 for low rise loads
and Figure I-15 for all heights. Previously the one wind uplift load applied to
a surface would be used for both the windward and the leeward cases. This
involved the following program changes:
a) Input
The Wind direction input is now enabled and
allows you to choose either direction or Both,
similar to a Wind shear load.
b) Graphics
In the Plan View and Elevation View, the wind uplift force is only drawn if the
direction of the uplift force matches the direction of load direction selected
in the Show menu.
c) Hold-downs
Different
uplift forces are used to create combined hold-downs at the same location for
different force directions. These appear in the Hold-down Design table.
d) Output
A Direction column was added to the Uplift Loads table,
2. Building Mass Generation for Separate Floors
(Bug 2386)
When
self-weights were entered in stages for several levels of the structure, and
building masses and loads generated at each stage, the loads due to the lower
portion of the wall mass from the storey above were not included in the
calculation if the loads were generated from top to bottom. Similarly, the
loads due to the upper portion of the wall mass from the storey below were not
included twice in the calculation if the loads were generated from bottom to
top.
Furthermore,
the calculation of total building mass used only the masses from floors that
had already been generated, leading to a different result than if the loads had
been generated all at once.
These
problems lead to significantly non-conservative loading when the loads are
generated in stages, particularly when it is done from top to bottom of the
structure.
They
have been corrected and the program now generates the correct seismic loads
when building masses are generated in stages. Note that the seismic loads that
are generated for a particular level after the entire structure is complete
will be different than those at an intermediate stage, because of the
difference in total building mass. The
loads generated at the intermediate stages should not be used for design.
3. Low Rise Wind Generation for
Multiple Blocks that are Deleted (Bug 2430)
When
walls were created using multiple blocks, then all but one of the roof blocks
are deleted, the program considered it a single block building when deciding
whether low-rise wind loads were allowed. The program used the walls created
from only one of the original constituent blocks to determine the height to
width ratio, and disallowed buildings that should be allowed. If the one block
used had an allowable h/w ratio, then the program generated wind loads on only
the walls on that block, and not on the rest of the building. Now, if multiple
blocks are used to create the walls, wind loads cannot be generated for
low-rise load design, and you are alerted with a message.
4. Cu Value for Sd < 0.4(
Bug 2454)
The value
of Cu (Sd < 0.4) from ASCE 7-05 Table 12.8-1 was
changed from the ASCE 98 value of 1.2 to 1.4 for ASCE 02, but Shearwalls still
used the 1.2 value. This affected the upper limit of period T = Ta*Cu,
that is imposed when you enter your own value of T rather than accepting the
calculated Ta. This resulted in higher-than-expected forces and
conservative design in this case.
5. Force on Perforated Walls in Shear Results (Bug
2496)
In
the shear results table, the shear force on each perforated wall is mistakenly
divided by the perforation factor, so that the sum of the wall forces exceeds
the total shear force on the shearline.
This
problem affects only the display of these forces in the output report, and the
incorrect values are not used for shearwall design, deflection analysis,
hold-down force or drag strut force generation.
6. ASCE 7 Minimum Load Reference (Change 115)
The
checkbox that allows you to impose minimum loads to the structure now includes
the ASCE 7 reference for these loads, 6.1.4.1.
C. Data Input and Program Operation
The
following problems with the operation of the Standard Wall input were
introduced with Version 8 of the program, unless otherwise noted:
a) Saving Newly Added Standard Walls
(Bug 2365)
When
adding a new Standard Wall you could not save the new standard wall unless you
had selected an existing standard wall as the basis for the new wall. If you
had selected a standard wall as a basis, the material, species and grade fields
are not initialized and must be edited in the Edit Standard Walls view before
exiting the view. If this is not done then you would lose any standard walls
that you had created in any session and Shearwalls reverts to using the
original set of standard walls.
These
problems have corrected.
b) Non-blank Fields when Adding New
Standard Wall (Bug 2367)
Originally,
when creating a new standard wall, the program would blank out all material
input fields, forcing the user to choose each one in turn. After choosing one,
it would only trigger the selection of another one if there was only one choice
for that input.
This
functionality became successively degraded with each release, and an increasing
number of fields became either non-blank from the start, or become selected
when another controlling field is selected. Other fields, however, remain
blank, creating an inconsistent look and behaviour.
All
fields now remain blank, if there is more than one choice, until you select
each of them in turn.
c) Standard Wall Identification (Bug 2418)
In Wall Input view, the program did not
always identify walls that are created identically to an existing standard wall
as being that standard wall, because of inaccuracies concerning the stud
thickness and depth. For example, this would occur when the width or depth were
changed, than changed back to those for the original standard wall. This has
been corrected.
d) Standard Wall Default Setting (Feature 139)
Because
the default standard wall selected in the Default
Settings applies only to the walls created from the blocks when first
entering Wall Input view, the name of
the Standard Wall data group box has
been changed to Standard wall for
exterior footprint. A note has been
placed in the box explaining that new interior walls depend on what is selected
in Wall Input view.
2. Default Load Type when Adding Loads (Feature
141)
The
program used to revert to the Dead
load type each time you added a new load. Now it uses the type of whatever load
is selected in Wall Input View, which
is the last load previously added. This allows you to enter multiple loads of
the same type without resetting the load type on each one.
Note
that the very first load you enter will now default to the type of the first
generated load in the list, instead of Dead.
If there are no generated loads, then Wind
shear will be the type of the first load entered.
3. Legend Checkbox in Options Settings (Bug 2398)
The
following issues with the operation of the Display Legend item in the Options
Settings have been corrected.
Control
of Material Specification
Turning
this option off also controlled the sheathing and framing materials as well as
the legend in Elevation View, even though there are separate options the
material specification. Now it controls only the legend.
a) Plan View
A legend
option has been added to control the display of the legend in Plan View.
b) Position of Legend Checkbox
The
legend option no longer appears between the similar options sheathing and
framing, it appears below them.
4. Hold-down Settings Dimensional Units ( Bug
2468)
a) Retention of Precision
The
values input into the Hold-down Settings box could lose precision when updating
after the following operations
-
After
being saved as a default for new files
-
Being
converted between imperial and metric
-
In
some cases, upon re-entering hold-down settings view
-
On
the case of the over-rides, immediately after entering the data
These
problems have been corrected, and in general values appear to 1/10 of a
millimetre and 1/1000 of an inch, however the program will show even millimetre
amounts without the decimal, and will remove all but one trailing zero after
the decimal place for inches. If more precise values are entered, they will be
retained internally, but will be replaced by the rounded value if view is
re-entered and another value is modified.
b) Bolt Hole Tolerance
In metric
units, the default bolt hole tolerance would sometimes appear as 0.0625 mm,
that is 1/16th of a millimetre. It is meant to be the metric equivalent of
1/16” . This has been corrected.
5. Deflection Analysis Setting Update (Bug 2327)
In Design Settings, the default values of
the Shearwalls Rigidity options were
not being reset when the Include
deflection analysis checkbox was reselected. Now, if you choose to do
deflection analysis, Use shearwall
deflection to calculate rigidity and Distribute
forces to wall segments based on rigidity are automatically selected.
6. Version Number in Program Name (Change 111)
Shearwalls
now has the version number in the name of the program that appears in the
program title bar, and over icons that appear in the start menu. This enables
you to quickly identify the version of the program you are running.
7. Wind Load Design Procedure Design Setting Name
(Change 105)
The
Design Setting Wind load design standard
has been changed to Wind load design
procedure, as there is now only one standard, ASCE 7, and the choice is of
procedures within that standard.
8. Spin Controls for Building Levels in
Generate Loads Input View (Bug 2387)
The spin
controls beside the Building Level
inputs in the Generate Loads input
form went missing, so that you had to type in a value instead of scrolling to
it. They have been restored.
9. Streamline Network Version Setup (Design Office
Feature 8)
The
procedure to set up multiple users running the program from a network server
has been streamlined, as follows:
a) Copying of Shearwalls.ini file.
Previously,
you had to manually copy a version of the Shearwalls.ini
file to all the client machines. The program now does this automatically.
It
is still necessary to modify the Sizer.ini in the server to indicate it is a
network version and give the location of the program on the server. A new step
is required, to copy the files from the Program
Data area of the server for All Users
to the corresponding folder in the Program
Files area of the server. In other words, the Shearwalls.ini file on the server will be found in one of the
following locations
Windows 7 -
C:\ProgramData\WoodWorks\CWC\Canada\8\
Windows XP -
C:\Documents and Settings\All Users\Application Data\WoodWorks\CWC\Canada\8\
After
modification, it has to be copied (not only moved) to the following location,
if the default installation was selected:
C:\Program Files
(x86)\Woodworks\Cdn\Sizer\
The
advantage of this approach is that the file has to be copied only once, and
within one machine, rather than distributed to several machines.
b) Modification of Database.ini File
With the
introduction of new locations for database and setting files with Version 8,
the network installation required you to modify the file Database.ini by
indicating it was a network installation. This is no longer necessary.
c) Instructions in “Read Me” File
The
instructions in the Shearwalls Read Me
file have been modified to explain the new procedure. In addition, the
following corrections have been made:
The
instructions regarding key code security instruct you to contact WoodWorks
sales, rather than using a key code that is delivered with the software.
Instructions
were given for those users who wish to modify the database files on their local
machine using Database Editor on the server. These have been removed, as this
procedure is not possible.
1. Full Height Sheathing Output for Excluded
Gypsum Walls (Bug 2355)
Shearwalls
that have no shear a capacity because they are sheathed entirely with gypsum
and Ignore gypsum setting is selected
would show a non-zero length of full-height sheathing in the Shearline, Wall and Opening Dimensions
table. Now the program shows a zero length in this case. The legend at the bottom has been modified to
indicate that the FHS column refers to the full height sheathing available for shear resistance.
Because
the Ignore gypsum setting is set
separately for seismic and wind design, an extra column has been added to the
table to show full-height sheathing length for wind and seismic
separately.
2. Interior Non-shearwall Material Information in
Elevation View (Bug 2352)
For
interior non-shearwalls, or for exterior non-shearwalls for seismic-only
design, known material input was showing up as Unknown in the elevation view material output. Now, if material
input is defined for an interior or seismic non-shearwall, then it shows up in
the material information. If the inputs
are left as unknown, they appear as unknown as there is no design for interior
or seismic non-shearwalls.
Note
that if shearlines are not restricted to All
walls the same and there is more than one non-shearwall on a shearline only
the material information for the southernmost or westernmost non-shearwall is
shown.
3. Floor Joist Length in Elevation View( Bug 2383)
In
Elevation view, for a multi-storey
structure with an upper storey overhanging the storey below, the floor joist of
the upper storey did not extend below the overhanging upper storey but only to
the end of the storey below. The overhanging portion of the upper storey was
therefore without a floor, and vertical elements supporting it had a gap
between the top of the element and the supported portion of the building.
The
program now draws the floor based on the length of the wall above. Now an end
portion of a wall that has no wall above it will no longer show a floor area
above it. Such a wall may or may not in reality have a floor area; it could
support a sloped roof instead.
This
is a display issue only that has no effect on load distribution or design.
4. Overlapping Hold-down Forces at
Vertical Elements in Elevation View (Bug 2389)
When
compression and tension hold-down forces are distributed downwards by a
vertical element, these forces shown in Elevation
view at the bottom of the element were drawn overlapping each other.
Furthermore the arrowhead for compression hold-down force in these locations
was often drawn within the joist depth rather than outside it as it is usually
drawn. This problem has been corrected and the compression and tension forces
are shown on either side of the bottom of the vertical element, with a
compression arrow of the correct size.
5. Overlap of Structure and Legend/Materials In
Elevation View (Bug 2405, 2388)
In Elevation view, lower portions of the
wall elevations often overlapped with the legend and materials specification.
These problems were more noticeable in Selected
Walls mode, and for deep joist depths
6. Precision of Design Shear Values in Shear
Results Output (Bug 2495) *
Starting
with version 9, the design shear values in pounds per linear foot, vmax and
V/FHS, appear in the shear results table as whole numbers. Previously they had
0.1 plf accuracy, which has been restored.
Shearwalls 9.13 – August 25, 2011 –
Design Office 9, Service Release 1c
7. Inability to Open Files after Retaining Database Files (Bug 2335)
Starting
with version 9.0 of the program, if you chose to retain your database files
from a previous installation, the program would be unable to open certain
project files. New files could also experience problems when trying to design.
This would also cause the program not to run due to incompatible standard wall
file, a problem that was partially rectified with Change 103 in version 9.11
below.
Shearwalls 9.12 – August 24, 2011 –
Hot fix
Version
9.01 released as a “hot fix”, a self-extracting file available from the
WoodWorks website to be expanded into the Sizer 9.0 installation. The first
Design Office edition that included these changes was Design Office 9, Service
Release 1c, released August 25, 2011.
8. Crash on Certain Roof Configurations (Bug 2334)
Starting
with version 9.0, certain roof configurations would cause a crash in
Shearwalls. These configurations contained at least three blocks, at least one
of which was only partially connected to another block, and at least one of
which was fully connected to another block. By “connected” we mean that the
extent of one edge of the block is within the extent of an edge of another
block, and the two blocks either overlap or abut one another.
This
has been corrected.
Shearwalls 9.11 – August 18, 2011 –
Design Office 9, Service Release 1b
9. Crash Upon Wall De-selection Program Operation
(Bug 2333)
If a wall
was selected, then an action is performed that caused the wall to become
de-selected such as moving back to Structure view, or extending walls upwards
then the program would crash the next time you entered wall input view. Simply
deselecting the wall within wall input view did not cause the problem. Note
that if you had made changes to the file, and want to continue with one of
these operations without losing the changes, it was possible to save the file,
close it, and re-open the file without problems. This problem has now been
corrected.
10. Standard Wall File Read/Open Error (Change 103)
The
error message that used to appear when the program had problems opening or
reading a standard wall file has been replaced with measures to rectify the
situation. If the program cannot read it because it is from an older version or
is corrupt, it creates a new one from default standard walls and replaces the
old or corrupt file.
If
the file cannot be opened because of file permission issues, such as a read
only designation or low user privileges, the program creates a set of default
standard walls that are stored in memory to be used for the duration of the
Shearwalls session.
The
program informs you via a message if one of these things is happening.
11. Moisture Content in Design Settings Output
Table (Bug 2322) *
If
there are no components and cladding wind loads on a structure the fabrication
and in-service moisture content was not output in the Design Settings output
table. However, deflection analysis now uses moisture content to determine
shrinkage when calculating the hold-down portion of deflection, so these fields
are now output when deflection analysis is performed as well.
Shearwalls 9.1 –
July 28, 2011 – Design Office 9, Service Release 1
This
version of Shearwalls addresses the following bug fixes and small improvements
to the program. The most important of these changes are E.1, E.2, H.1, and H.2.
1. Rigid Diaphragm Distribution using Deflection
for Low-rise Wind Loads (Bug 2294)
For
ASCE low rise wind loads, rigid diaphragm distribution to shearlines with
stiffnesses based on deflection analysis was unreliable, and any design based
on it should be re-evaluated.
For
example, because there are no torsional effects for low-rise wind loading, the
program should distribute loads equally to two identical lines on a symmetric
building; however there is a sharp difference in shearline forces when
distributed using deflection.
When
distributed using capacity, the shearline forces were equal as they should be.
This
problem has been corrected.
2. Bi-Directional Seismic Rigid Diaphragm Analysis
(Bug 2282)
The
program did not do seismic rigid diaphragm analysis in both force directions,
it only analysed east-to-west and south-to-north directions. This became
problematic when deflection analysis was added to the program; due to hold-down
configuration, stiffness can be different in opposing directions, so that rigid
analysis is required in opposing directions.
Note
that direction of force was being considered when distributing shear within the
line, based on the stiffness of individual segments, as it should be.
In
Plan view, the seismic shear force was displayed as a bi-directional force, now
it is displayed as a directional force (similar to how wind forces are
displayed). When you select to display critical forces, the worst case seismic
force on each shearline is now displayed.
3. Wind Uplift Loads over Openings (Bug 2132)
When a
wind uplift load is applied to an entire wall line, the uplift load did not
appear over openings in elevation view, and the load over the openings was not
distributed to the hold-down forces at the sides of the opening.
4. Restraint
force t in Combined Hold-down Forces for Wind vs. Seismic. (Bug 2318)
For
multi-storey structures with a perforated wall on an upper floor containing
openings, and offset walls or openings on the floor below, the combined wind
hold-down force mistakenly contained the seismic restraint force t from SDPWS
4.3.6.4.3.1 if one existed.
This
effect is usually small and conservatively increases the hold-down force.
1. Windward Roof Pressure for Exposure B, High
Roof Slopes (Bug 2106)
When generating wind loads under the
following conditions
• ASCE 7
All Heights
• with
a roof slope greater than 45 degrees,
• Exposure
B ( built up urban areas )
• The
imposition of minimum wind loads is enabled in the Generate Loads view
the
transverse-to-ridge windward loads and forces were corrupted as follows:
-
The
meaningless symbol “-1.$” is shown as the magnitude in
plan view and the loads table of the results report.
-
In the plan and elevation graphics view, the
shearline force was an unrealistically large negative number.
-
No shear force for the these lines was displayed in the shear results of the
results report.
These
problems for this one rather rare case have been corrected.
a) Maximum
Period T Check (Bug 2130)
Previously,
the program warned you when entering a value of T in the site information box
greater than the maximum limit on T given by ASCE Section 12.8.6.2, Tmax =
CuTa, but allowed you to enter it anyway. It did not indicate anywhere in the
output that this limit had been violated. Now it does not allow you to enter a
period greater than Tmax.
b) Period
T Greater than Maximum (Bug 2280)
When
you entered a period T in the Site Dialog that was greater than the maximum
given in ASCE 7 12.8.2 , and the program prompted you to accept the maximum
instead, it applied the maximum to the North-south direction, but not the
East-West Direction. In the East-west direction, the entered period that is
greater than the maximum was used, resulting in lower than allowed loads, a
non-onservative error.
This
problem has been corrected.
c) Repeated
Maximum Period T Warning (Bug 2302)
In the
Site Information dialog, if during exiting the dialog a message box informs you
that a Ta value is greater than the T max value allowed by ASCE-7 and you
choose to set this Ta value to the T max, the next time the Site Information
dialog is exited with the OK button then the message would appear again even
thought the maximum Ta value was applied. This has been corrected.
C. Engineering Design and Deflection Analysis
1. Wind Capacity Increase Factors (Change 99)
We have
removed the ability to enter the Wind Capacity Increase factors in the Design
Settings, because these inputs have become outdated. They have also been removed from the Design
Settings output echo. If a file created with a previous version has factors
other than those in the SDPWS and NDS design codes, the factors are changed to
the design code values.
a) Allowable Shear Stress Adjustment
The
allowable shear stress adjustment is showing the ratio of capacities for wind
design vs seismic. This was more important for the older IBC (2306.3 in
2009, 2306.3.2 in 2006) that allowed the increase. The IBC now refers to
the SDPWS, which has separate columns for wind and seismic capacities.
Note
also that the 1.4 increase doesn’t pertain to lumber sheathing, so this removes
this complexity from the program, in which the program used to factor lumber
sheathing by the ratio of 1.4 and the entered value.
b) C&C Load Duration for Nails and Sheathing
Removing
this eliminates confusion between the 1.6 duration factor increase vs. the 1.6
reduction from the published nominal values in SDPWS table 3.2.1 to the ASD
values. Both of these factors are taken care of internally now.
Although
NDS 2.3.2 refers to these as “frequently used values” and presumably optional,
and WoodWorks Sizer allows them to be modified, Shearwalls does not allow the
duration factors for MWFRS to be changed, so it is inconsistent to leave them
in for C&C design.
2. Tolerance in Determining Segment Loading
(Change 92)
If the
force on a segment is less than ½ pound, it is considered to be zero and
deflection and hold-down calculations are not made for that segment. Previously
the tolerance was 0.1 lb, which led to segments that showed a zero force having
significant deflection.
3. Elongation Override for Unloaded Segments
(Change 93)
The
program was assigning a deflection due to hold-down elongation for segments
that attracted zero loading when that elongation was taken from the override in
the Design Settings. The program now assigns zero elongation in that case.
Fixed
“Cancel” of design such that it cleans up the what it is doing on the current
floor and then exits. Previously it was doing large amounts of unnecessary
processing, and the box would freeze on the screen, but not do anything or
affect the program.
1. Program Data File Locations (Bug 2265)
Because
Windows 7 and Windows Vista operating systems do not allow write access to the
Program Files folders to those users who are not running the program as
Administrator, making it impossible for them to save changes to the stud
material database, the hold-down database, settings, and standard walls, these
files are now placed in a new location by WoodWorks.
It
was also necessary for those users who were not administrators on their
computers to enter a keycode each time the program was run.
These
restrictions were more severe on Windows 7 than Vista.
The
program now stores the support files for the program in the following folders
Windows
7/Vista:
C:\Users\[username]\AppData\Local\WoodWorks\CWC\USA\9\
Windows
XP
C:\Documents
and Settings\[username\]Local Settings\Application Data\WoodWorks\CWC\USA\9\
a) The program also saves the files to the
following folders:
Windows
7
C:\ProgramData\WoodWorks\CWC\USA\9\
Windows
XP
C:\Documents
and Settings\All Users\Application Data\WoodWorks\CWC\USA\9\
These
are repositories for the files to be copied to each new users’s data folders
when they first use the program. This allows a system administrator to install
the program, but others to use it without restrictions.
A
more complicated set of procedures for network installations is described in
the Read Me files for each program.
2. Crash for Non-Administrators Due to Temporary
Log File (Bug 1990)
For
Windows Vista and Windows 7 operating systems, those users who do not have
administrator privleges can experience a crash when running a project that has
previously been designed, Shearwalls will crash.
Deleting
or renaming the log file in the project folder prevented the crash.
The
program now places the temporary file
that it uses to construct the log file in the
folder designated by Windows for program data, preventing the crash.
3. Hanging or Crashing on Design (Bug 2312)
Occasionally,
the program would hang indefinitely or crash when the design button was
invoked. The known instances of this problem have been corrected.
4. Saving of OSB Material Property (Bug 2290)
The OSB
property in the Wall Input View did not save to file. Even If checked, saved
files would always show an unchecked OSB checkbox when reopened. This property
is now saved.
5. "Unknown" Exterior Gypsum Wallboard Thickness (Bug
2200)
In
Wall Input view, if gypsum sheathing with more than one choice of thickness is
selected as the material for the exterior surface, the choice of "unknown" was unavailable from the drop down list of
thicknesses to chose from.
Now,
"unknown" is available, unless there are structural wood materials on
the other side of the wall.
6. Building Level in Wall Materials Input Label
(Bug 2291)
The label
on the group box in the wall input form surrounding the wall materials often
showed a building level other than the one you had selected to modify the
materials on. It now shows the correct level.
7. Factory Default Hold-down (Change 95)
The
default hold-down in the database shipped with Sizer has been changed to HD9
from HD7. This is because the default number of studs at a wall end is 2, and
HD7’s do not have design values for 3” built up studs. For this reason, the
default configuration in shearwalls would take its deflection and capacity
values for hold-downs from the over-rides in the hold-down settings rather than
the actual hold-down.
8. Drag strut spelling (change 82)
Wherever
the word dragstrut appears in
Shearwalls, it has been changed to drag
strut.
1. Total
Wall Shear Force in Shear Results Output (Bug 2301)
If you do not specify in the design settings to distribute forces to wall
segments based on rigidity, then the total shear force V on a wall reported in
the shear results table is mistakenly divided by the length of the wall in
inches, yielding a very small number. This does not happen if you set the
rigidity method to be “Equal rigidities”, but does for the other three options.
This
had no effect on loads analysis or design, it was just a problem in tht output
form.
2. Hold-down
Type and Capacity Reporting (Bug 2319)
The
hold-down type and capacity reported in the hold-down output table was
sometimes giving the values for the left side of the wall segment for the right
side, and vice-versa. This had no effect on load distribution or shearwall
design, it was just a reporting error.
3. Duplicate
Case 1 Wind Loads (Bug 2179)
When
Case 1 Wind Loads and ASCE All Heights
Method is selected in the Design settings, each wind load was duplicated in the
Loads able of the Results report and the log file.
They
now appear only once.
4. Repeated
Rigid Diaphragm Analysis in Log File
(Bug 2314)
When a
design is run on a structure, the Rigid Diaphragm Analysis data was being
output twice in the log file. It is now output only once.
5. Rigidity
Method Descriptor in Design Settings Output (Bug 2321)
In
output of the descriptors for the “Shearwall rigidity per unit length” design
setting did not take into account that the program longer uses walls designed for flexible
analysis to determine rigidities, and also used the same expression for
deflection-based analysis as was used for capacity-based.
New
descriptors have been made to accurately describe the options.
6. Log File Torsional Rigidity Output and Units
(Change 90)
-
The
notation of the units for the torsional rigidity due to the stiffness of a
shearwall based on deflection has been changed from kips/in-ft^2 to kip-ft^2/in.
-
Scientific
format was used when the torsional rigidity value was > 1.0 ^6, now
scientific format is used only if the torsional rigidity is greater than 108
7. Warning for Hold-down Displacement from
Override (Change 94)
A warning
in red has been added under the Hold-down displacement table if any of the
displacements in the table have been taken from the over-rides in the Hold-down
settings because there is no
8. Drag Strut Force Direction (Change 89)
Drag
strut forces in the E->W direction were reported in the column for the
W->E direction, and vice-versa. This has been corrected.
9. Allowable Storey Drift Units (Change 88)
In the
Story Drift table, the Delta a column header for allowable storey drift gave
the units as feet when the units are actually inches. This has been corrected.
10. Warning for Zero Capacity Seismic Design Categories
(QA Item 8)
a) When a material had zero capacity because it
was not allowed for the Seismic Design Category, the program placed two
asterisks in the Critical Response column, with no explanation for these
asterisks. Now a warning appears below the table explaining the reason for
them.
11. Hold-down Design and Drag Strut Table Legends
(Changes 77, 79, 83, 101, 102)
In the
legend for the Hold-down Design table
a) Earthquake Forces
-
Changed "Vert E" to Ev and "vertical
earthquake load" to "Vertical seismic load effect" be consistent
with ASCE terminology
-
Added
notes explaining the horizontal load effect Eh from ASCE 7 12.4.2
b) Load Combinations
-
Added
note for load combination used from ASCE 7 2.4.1.
-
Added
0.7 factor in description of shear overturning component
c) Vertical Elements
-
Changed
“Vert Elem” to V Elem, to accord with heading
-
Added
vertical element explanation to “Line-Wall” description.
d) Other Clarifications
-
Added Position of.
before stud that hold-down is attached to
-
Change
* multiplication symbol to x
In both
the legend for the Hold-down Design table and the Drag Strut Table:
e) Applied Load or Sheathing Capacity
The
program now indicates in the legend whether the hold-down design force shown is
based on applied shear force or shearwall capacity. A setting in the Design
Settings controls this.
12. Deflection Table Legend (Change 79 )
The Wall
Group item has been explained more fully.
1. Long
Hold Down Symbols for Zero Joist Depth (Bug 2102)
In the
elevation view, the hold-down symbols were extremely long when the joist depth
the symbol spans is zero. The symbols are now drawn about 4" long in that case.
2. Vertical
Seismic Force in Elevation View Legend (Bug 2145)
The
portion of the legend in elevation view that shows the load combinations S - D (tens) and S + D (comp) has now been
revised to include the vertical seismic load effect Ev. The legend now says S - D + Ev (tens); S + D + Ev (comp).
3. Shearwall
Material Options for Elevation View (Bug 2150)
In the
Display group in the Options Settings, and the corresponding menu items in the
Show menu for Elevation View,
-
The
“Nailing” choice was removed because the nailing is on the same line as the
sheathing.
-
An
item has been added to turn on and off the legend, to allow for more vertical
space.
4. Factored
Dead Load Component of Compression Force (Bug 2155)
For
compression forces at hold-down locations, the dead component displayed in
Elevation View was factored by the uplift factor (0.6) instead of the gravity
factor (1.0).
The
correct factor is included when the hold-down forces are combined, and it is
the unfactored force that is distributed downwards, so this problem had no
effect on hold-down design or deflection analysis.
Shearwalls 9 – Oct 21, 2010 – Design Office 9
This
version of Shearwalls implements
Shearwall deflection analysis according to SDPWS 4.3.2 and C4.3.2, using the
4-term equation in C4.3.2. Includes rigidity derived from deflection, force
distribution by equalising deflections on line, and storey drift check.
A
hold-down connection database and holworstd-down design.
Iterative shearwall design, using initial iteration to calculate
rigidities for final design.
The
2008 version of the AWC Special Design Provisions for Wind and Seismic (SDPWS
2008), replacing the 2005 version
the
2009 version of the ICC International Building Code (IBC 2009), replacing the
2006 version
Supplement
2 to the ASCE 7-05.
A
number of smaller improvements and fixes. The following fixes involve
non-conservative and/or possibly large discrepancies in engineering calculations;
please check existing projects to see if they may have been affected: Bugs 2187, 2189, 2190, 2192, and 2193.
A
complete description of design changes is given below. Use the following links
to navigate to the major sections:
Design Code
Updates – SDPWS 2008, IBC 2009, and ASCE 7-05 Supplement 2
The ability
to input hold-down connections to Shearwalls from a hold-down database for use
in design for overturning forces and for deflection analysis has been added to the
program. Previously Shearwalls reported hold-down forces at each hold-down
location, but did not specify the hold-down connections used.
1. Hold-down Types and Properties
a) Hold-down Assembly
The
hold-downs in shearwalls connect the wall end studs on an upper level to either
the corresponding stud on a lower level or anchored to the foundation. Continuous
tie rod systems extending over multiple building levels are not included in
this version of Shearwalls.
i. Vertical Connection
Hold-downs
include either an anchor bolt or threaded rod which connects upper and lower
brackets or straps, or a continuous strap extending from upper to lower level.
ii. Horizontal Fasteners
The
connection from bracket or strap to the upper and lower studs is made via bolts
or nails.
iii. Single or double bracket
Hold-downs
are designated as being either single-bracket or double bracket, indicating
that the hold-down has a bracket or strap on one floor or both. By default,
hold-downs on the ground level are single-bracket, and upper-level hold-downs
are double-bracket. The data in the hold-down database are published for one
bracket only and are doubled when the hold-down is designated as double bracket
in the Shearwalls program.
iv. Shrinkage Compensating Device
You can
designate that the hold-down includes a mechanical device to adjust for the
shrinkage of the perpendicular-to-grain wood between the extreme hold-down
fasteners, so that such shrinkage is not included in the calculations for
shearwall deflection.
b) Displacement and Capacity Sources
Different
hold-downs are designated in Shearwalls for the following different means of
publishing displacement and capacity values. There are three possible sources
of vertical hold-down displacement that affects shearwall deflection:
-
anchor
bolt elongation,
-
bracket
or strap elongation,
-
slippage
of horizontal bolts or nails.
Similarly,
the capacity of the hold-down takes into account the possible failure in
tension of the bracket or strap, the anchor bolt in tension, and the connection
of the horizontal fasteners to the wood studs.
The
published data may include all or just some of these sources. For displacement,
sources that are not included are calculated separately by Shearwalls. For
capacity, sources that are not included are neglected by Shearwalls, with an
appropriate warning message.
The
hold-down types corresponding to displacement/capacity data source are
Displacement
values refer to entire hold-down – bracket or strap, anchor bolt, and
horizontal fasteners. Capacity takes into account tensile capacity of brackets
and straps, and wood-connection capacity of horizontal fasteners. Anchor bolt
displacement applies to a maximum length, elongation of portion greater than
that length is analysed separately.
ii. Separate Slippage, Combined Elongation
Displacement
values refer to the elongation of the brackets or straps plus the anchor bolt,
to a maximum length. Elongation past the maximum length is analysed separately.
Capacities include only the tensile capacity of the brackets and anchor bolt. Slippage
of fasteners is calculated by Shearwalls, and wood connection capacity of the
horizontal fasteners is not considered.
iii. Separate Slippage, Separate Elongation
Displacement
values refer to the elongation of the brackets or straps only. The entire
anchor bolt length is analysed separately. Capacities include only the tensile
capacity of the brackets. Wood connection design of the horizontal fasteners is
not included, and capacity of anchor bolt is not considered.
c) Method of Determining Displacement
Hold-downs
are designated according to the method we use for determining the vertical displacement
under loading, as follows.
i. Displacement at Actual Force
With
this method, ratio of the ASD capacity of the hold-down to the maximum ASD
capacity is multiplied by strength-level displacement to give the displacement
used for deflection analysis and storey drift. When Assembly Displacement (see
above) is used as the data source, the assumption of linear may not bet
correct, due to the non-linear effects of fastener slippage. This would yield
non-conservative results for storey drift determination. However, the choice
also affects load distribution to and within shearlines using stiffness
analysis, for which the effect may be conservative or non-conservative.
ii. Displacement at Maximum Capacity
With
this method, the published displacement at maximum capacity is used regardless
of the shearwall force. This ensures
conservative storey drift calculations when Assembly Displacement (see above)
is used as the data source, but may be overly conservative for other choices.
This choice also affects load distribution to and within shearlines using to
stiffness analysis, for which the effect may be conservative or
non-conservative.
The
program includes a database of standard hold-downs, which you can edit using a
database editor incorporated in Shearwalls to update hold-down properties or
add new hold-downs
a) Database File
The Database folder of the WoodWorks
installation contains a file called Holddowns.mdb,
which is a Microsoft Access database
of hold-downs used by the Shearwalls program. Shearwalls now includes an editor to modify the database, but it is
also possible to modify the file directly via Microsoft Access.
b) Database Structure
The
database consists of two tables, a Hold-down table that contains the properties
of the hold-down that are relevant to Shearwalls design, and a Displacement
table which contains hold-down capacities and displacements corresponding to
each combination of minimum stud width and depth. The record in the
displacement table contains a reference ID to the hold-down that uses that
displacement record.
i. Hold-down Table
The
hold-down table contains the following data:
-
Name
-
Horizontal
fastener type ( bolts or nails)
-
Number
of horizontal fasteners (per bracket or strap)
-
Horizontal
fastener diameter
-
Whether
it includes an anchor bolt
-
Anchor
bolt diameter
-
Whether
published elongation and fastener slippage are combined into one displacement
-
Whether
published elongation includes the anchor bolt, or it is for the bracket/strap
only
-
The
maximum anchor bolt length for which the published elongation applies
-
Whether
for this hold-down, we use displacement at maximum capacity for deflection
analysis
-
Whether the hold-down includes a shrinkage
compensation device
-
Whether
the hold-down is to be used as the default hold-down for new projects in
Shearwalls
The
meaning of these variables is described more fully in the section on Database
Input.
ii. Displacement Table
The
hold-down displacement table is needed for hold-downs for which the entire
assembly displacement is published. For those hold-downs for which only the
bracket or strap elongation is published, then only one displacement record is
needed, corresponding to the elongation of the bracket or strap. The
displacement of anchor bolt and horizontal fasteners is calculated separately
by Shearwalls using the information in the Hold-down table.
c) Initial Hold-downs
The file
in the Shearwalls installation contains a limited number of hold-downs, from
the Simpsons Strong-Tie Bolt Hold-down Evaluation Report 0143 (June 2009,
expires June 2010) and the Simpson Strong-Tie Nail Hold-down Evaluation Report
0130 (Dec 2008, expires Dec 2009).
i. Bolted Hold-downs
The
hold-downs in the initial database that are connected to the upper and lower
studs via bolts, from evaluation report 0143, are HD2A, HD5, HD7, HD9, HD12,
and HD19. For each of these, there is a corresponding hold-down, e.g. HD2A-2,
for which the displacements are taken from Table 2 of the evaluation report. For
the hold-downs from Table 2, the displacement values are for the hold-down
bracket only, and the anchor bolt elongation and horizontal bolt slip are
analysed separately by Shearwalls. The displacement values for hold-downs from Table
1, e.g. HD2A, are for the entire hold-down assembly.
ii. Nailed Hold-downs
The
hold-downs in the initial database that are connected to the upper and lower
studs via nails, from evaluation report 0130, are LTT19, LTT20B, LTTI31, HTT4,
HTT16, and HTT5, HTT22. The displacements for these hold-downs are for the
entire assembly (nails, anchor bolt, and strap). However, it is possible to
enter nailed hold-downs into the database for which these components are
analysed separately by Shearwalls.
iii. Strap Hold-downs
There
are no hold-downs in the initial database consisting of one continuous strap
without an anchor bolt; however it is possible to add this type of hold-down to
the database.
d) Single vs Double Bracket Hold-downs
The displacement
data in the hold-down database applies to just one bracket or strap of a
hold-down. In the program, hold-downs designated as double-bracket have the
displacement values doubled, and the maximum anchor bolt length is also
doubled. The capacity data applies to
each bracket of the hold-down, and is never doubled.
When
creating a hold-down with a continuous strap, you can either
-
enter
hold-down data that apply to the elongation of the entire strap and the total
number of fasteners, top and bottom, and
designate it as single-bracket in Shearwalls
-
enter
hold-down data that apply to the elongation of ½ the strap, and the fasteners
on one level, and designate it as double-bracket in Shearwalls.
The
program includes an editor to view and modify the hold-down data. This editor
should be used to update hold-downs for newly published product information
from the hold-down manufacturer. It can be also used to add new hold-downs.
a) Access
The
database editor is accessed from the following locations:
-
An
item in the main menu
-
A
button in the Plan View and Design Results window’s toolbars
-
A
button in the Hold-down data group in
Wall Input and Opening Input views
b) Context sensitive help
Each of
the input controls within the database editor has context-sensitive help,
explaining its purpose and use. If you click on the question mark in the upper
left hand corner of the view, then on the input control a small yellow box
appears with the description of the item.
The
following are brief descriptions of the input fields within the box; for more
details, use the context-sensitive help in the program.
c) Hold-down Selection Controls
The Hold-down selector, New and Delete buttons,
and Default… checkbox are used to
control the current hold-down being edited.
i. Hold-down Selector
The
hold-down selection dropdown is used to both select the hold-down for viewing
and editing properties, to name a new hold-down, or to rename the hold-down by
typing over the existing name. It sorts the hold-downs from the database
alphabetically.
ii. New
Changes
the input mode to refer a new hold-down being created rather than an existing
one being edited.
iii. Delete
Used to
delete the currently selected hold-down from the database. Must delete
incomplete entries before exiting box.
iv. Default hold-down in Shearwalls
Indicates
that this hold-down is the one that is used when new walls are created in
Shearwalls.
d) Fasteners – Horizontal (slippage)
This
group pertains to the horizontal fasteners connecting hold-down bracket or
strap to the wall end studs. This group is not active when full assembly
displacement is specified (combined elongation and slippage), as the fastener
information is not needed in this case.
i. Bolts/Nails
Used to
select fastener type. Bolts are assumed to extend through the stud ( not lag
bolts). Nails are assumed to be common wire nails.
ii. Diameter
Shank
diameter of bolt or nail – can select from list or enter custom size.
iii. Number
Number
of fasteners connecting one bracket or strap to wall end stud on upper or lower
level.
e) Vertical Bolt ( add’l elongation)
This
group pertains to the anchor bolt which connects the upper hold-down bracket or
strap to lower bracket or strap, or to the foundation or some other anchoring
mechanism.
i. No/with anchor bolt
Radio
buttons allow you to indicate that the connection does not have an anchor bolt,
disabling the other controls and causing the program to dispense with anchor
bolt calculations.
ii. Diameter
Shank
diameter of anchor bolt, used in tensile strength and elongation calculation, –
can select from list or enter custom size.
iii. Max Length for Given Elongation
The
length of anchor rod the manufacturer used in tests to determine the
displacement or elongation, usually found in a note in the product literature
or evaluation reports. Elongation for any excess bolt length is calculated
separately by Shearwalls.
f) Options
There
are checkboxes in the view for the following options:
i. Elongation and Slippage Combined as Single
Displacement
The
published displacement includes deflection from fastener slippage and from
elongation of brackets or straps, or the
published displacement is from elongation only, and slippage is calculated
separately. Is checked for the Assembly Displacement method (see 1b, above).
ii. Elongation for Connector Only (without Anchor
Bolt)
The
published elongation is for the brackets or straps only, or is for the anchor
bolt as well. Used to create the Separate
Slippage, Separate Elongation, or Separate
Slippage, Combined Elongation displacement methods (see 1b, above). Can’t
be used when elongation and slippage are combined.
iii. Shrinkage Compensating Device
If
hold-down a mechanical device to adjust for the shrinkage of the
perpendicular-to-grain wood between the extreme hold-down fasteners.
iv. Always use Elongation at Maximum Capacity
A
checkbox is used to implement the choices described in Method of Determining Displacement in 1c, above.
g) Elongation/Displacement
This
Data Group allows you to enter different hold-down ASD capacities and/or displacements
depending on stud width and thickness. It refers to “Displacement” when the
Assembly Displacement method ( see 1b) is used, otherwise it refers to
Elongation
i. Elongation/Displacement List box
This box
allows you to replicate the tables that appear in the hold-down product
literature that have different hold-down capacities and/or displacements for
each stud thickness and/or depth.
Generally speaking, a number of records is needed for the Assembly Displacement type of data
source ( see 1b, above). It is also possible to enter just one record that
applies to all stud sizes, which is appropriate to the Elongation data sources.
The
values apply to only one bracket in a
two-bracket hold-down.
ii. New
Creates
a new record corresponding to a line in the table of product information.
iii. Delete
Delete
an entire record consisting of one line of the Displacement/Elongation table. You must delete any incomplete lines before exiting the dialog.
iv. Note
For any
line in the table, you can enter a note corresponding to the one that appears
in the product literature and/or evaluation report to show in the design
results any further restrictions on the use of the hold-down, such as on the
wood species, grade, or specific gravity.
There is
similar input for hold-downs at two places in the program – the Wall Input form and Opening Input form. In each place, a hold-down data group contains
the following input fields:
i. Hold-down drop-list
For both
left and right ends, used to select the hold-down to be used from the list in
the database.
ii. Single- or double-bracket
A
checkbox indicates that the hold-down is double bracket, that is, the
displacement and maximum anchor bolt length entered in the hold-down database
applies to only one-half of the assembly, and is doubled for the hold-down
assembly used.
iii. Apply to Openings
When
this is checked, the inputs apply to all openings on the wall as well as the
wall end studs, saving you the effort of updating all the openings manually.
The
input of these data applies to all selected walls.
The following
has been added to the Framing data
group of the wall input view:
i. Grade
The
grade value is now active for all materials. Previously it was active only for
MSR and MEL, for which grade data is needed for the specific gravity, which
affects for shearwall capacity.
ii. Thickness and Width
In wall
input view, the stud thickness (b dimension) and width ( d dimension) is input, either by selecting from a list of
nominal sections from the database or by typing your own actual value in. The
input control behaves in a similar manner to the Width and Depth input in
Sizer.
Note
that the thickness (b) and width (d) terminology for studs is consistent with
product literature, and should not be confused with the width (b) and depth (d)
terminology for all members in Sizer.
It is
assumed to apply to all studs in the wall, including those at openings and wall
ends (which can be built-up from more than one stud.)
For
projects created before version
iii. Number of End Studs
Typically
wall ends are at least doubled and at times more plies are added to provide
tensile or compressive strength or connection strength for the hold-downs. The
input of the number of end studs at both left and right end has been added to
allow the program to select the hold-down capacity and displacement for the
Assembly displacement method (see 1.b)i above). The program does not as yet
design the built-up studs themselves.
This
input has also been added to the Hold-downs
data group (see a) above) in the Opening Input view for the wall studs at the
hold-down locations at each side of an opening.
c) Structure Input
New
inputs have been added to the Structure Input form that allow for input of
parameters that apply to all hold-downs on a single building level.
i. Length Subject to Shrinkage
This
input indicates the total vertical extent of perpendicular-to-grain wood
members spanned by the hold-down device. Typically the depth of the floor
joists plus two top plates on the lower level and one bottom plate on the upper
level. For ground level, it depends on the sill plate configuration. Used in
hold-down wood shrinkage calculations.
ii. Anchor bolt length
This
indicates the required length of the hold-down anchor bolt, if one exists for a
particular hold-down. Typically the length subject to shrinkage plus flooring
material thickness. However, in some situations it could be quite different,
for example when wood I-joists are used. The I-joist web is included in the
anchor bolt length but not in the length subject to shrinkage.
iii. Context sensitive help
Each of
these fields have context-sensitive help explaining their use, accessed via the
question mark box at the top of the dialog box.
A new
page has been added to the Settings input for hold-down data that apply to all
hold-down locations in the structure.
a) Context sensitive help
Each of
the input controls within this settings page has context-sensitive help,
explaining its purpose and use. If you click on the question mark in the upper
left hand corner of the view, then on the input control a small yellow box
appears with the description of the item.
The
following are brief descriptions of the input fields within the box; for more
details, use the context-sensitive help in the program.
b) Hold-down forces
A new data
group is added to include options affect the generation of hold-down forces
from shearline forces on segments.
i. Hold-down Offset
This has
been moved to this page from the Default
Values page. In addition, the
following capability is added:
If a
value is entered that is greater than or equal to ½ a shearwall segment length,
the program reverts to the factory default value of 1.5” for that segment. It
issues no warning in this case, it is evident only by the placement of the
hold-down in elevation view and its position as listed in the Hold-down Design
table.
ii. Subtract Offset…in Moment Arm Calculation
A
checkbox indicates whether the program subtracts the hold-down offset from the wall
length when calculating the overturning moment arm. AWC SDPWS 4.3.6.1.1 (Eqn.
4.3-4) indicates that this distance is not subtracted, however engineering
mechanics, particularly when there is only one shearwall on a line, require
that it be subtracted.
The default
value is to subtract the offset. For project files from previous versions, the
offset is not subtracted, so as not to affect existing design results.
iii. Include Joist Depth…in Moment Arm Calculation
A
checkbox iindicates whether the program includes the floor depth above the wall
in the wall height h when calculating the overturning moment arm. AWC SDPWS
4.3.6. Eqn. 4.3-4,5 indicates that this distance is not included, however
this creates gaps in the static analysis of multi-level structures.
The
default value is not to add the joist depth subtract the offset. For project files
from previous versions, the offset is not subtracted.
c) Displacement da for Deflection – Override
Hold-down Properties
The
inputs in this data group allow you to replace the vertical hold-down
displacement components from with constant values for all hold-downs in the
program. They also allow you to specify values for these components if they cannot
be calculated or are not available from the hold-down database for a particular
hold-down. A warning appears in the output if this situation occurs.
i. Elongation
If box
is checked, the program uses the input value as the elongation for all
hold-downs in the structure that have separate elongation/slippage, overriding
the hold-down database value. If box is not checked, it uses the override value
only when a value is not available from the database for the stud size that the
hold-down is attached to.
ii. Displacement
If box
is checked, the program uses the input value as the elongation for all
hold-downs in the structure that have combined elongation/slippage, overriding
the hold-down database value. If box is not checked, it uses the override value
only when a value is not available from the database for the stud size that the
hold-down is attached to
iii. Shrinkage
If box
is checked, the program uses the input value as the wood shrinkage value for
all hold-downs in the structure, overriding the value calculated using moisture
content and length subject to shrinkage on each floor.
iv. Slippage
If box
is checked, the program uses the input value as the nail slippage for all
nailed hold-downs in the structure that have separate elongation/slippage,
overriding the hold-down database value. If box is not checked, it uses the
input value only when the force Vn on each nail is greater than the maximum
allowed in SDPWS Table C4.2.2D.
d) Displacement da for Deflection – Wood
Properties and Construction Detail Settings
Data for
hold-down displacement calculations that cannot be entered independently at
each hold-down location is entered here.
i. Default Length Subject to Shrinkage
Used to
enter the proportion of the floor depth as input in the Structure input view,
plus the depth of other wood members such as wall top and bottom plates that is
subject to shrinkage. This value can be
adjusted for individual floors in Structure Input view, it is of primary use in
creating defaults for new files for these values.
ii. Crushing of Bottom Plate at End Stud
The
deformation of the bottom wall plate beneath the end chord studs at the
compression end of the shearwall. The “factory” default is 0.04 corresponding
to lumber loaded to capacity for perpendicular compression according to NDS
4.2.6. A value of 0.02 corresponds to lumber loaded to 73% capacity.
iii. Other (miscuts, gaps, etc.)
Additional
sources of vertical shearwall displacement are input here at the discretion of
the designer. This could include allowance for studs that are cut too short or
without square-cut ends
iv. Bolt hole tolerance
The
difference between drilled hole diameter in the studs and the diameter of the
horizontal bolt shank. For Assembly displacements that include slippage (see
1b, above), any value greater than 1/16” is added to the published
displacement, which includes the effect of standard size bolt holes. For
separate slippage and elongation, the entire value is added to the calculated
slippage.
a) Hold-down Location
The
program performs the design check for hold-down capacity at each wall or
opening end.
i. Vertical elmenents
There is
currently no mechanism for entering hold-downs at the base of vertical elements
transferring a force from an upper storey via a vertical element to a location
on a lower story that is not a wall or opening end on that story. so is no
hold-down design for those hold-down locations.
b) Design Cases
For each
design case (wind, seismic, and both force directions), the program checks the
ASD capacity of the hold-downs at each hold-down location against the combined
ASD factored uplift force. The combined force includes:
shear
overturning
counteracting
dead load
wind
uplift
special
perforated wall loads (SDPWS 4.3.6.4.2.1), only in the cases where openings on
a lower level are not below a similar opening on the upper level)
vertical
earthquake loads ( ASCE 7 12.4.2.2)
c) Design Method
This is
a design check only on a hold-down selected for the hold-down location. The
program does not at this time cycle through various possibilities to find a
hold-down.
a) Hold-down Design Table
The
Hold-down and Drag Strut table has been split into two tables, one for
hold-downs and one for drag struts. The new Hold-down design table includes
hold-down capacity design information.
i. Hold-down Device
A column
has been added to indicate the name of the hold-down device from the database
used at hold-down location.
ii. Capacity
The ASD
capacity of the hold-down at that location
iii. Crit Resp.
The
ratio of combined, factored hold-down force to capacity. A value greater than
one indicates a failed design.
iv. Legend
The
legend has been split up to show information pertaining to each column on a
separate line, edited for clarity. Information about uplift force for
perforated walls for staggered openings added. Lines describing new data added.
v. Notes
Note for
dead load factor removed and value of factor placed in legend. Note for seismic
anchor bolt washers now refers to SDPWS 4.3.6.4.3 and 4.4.1.6, not IBC.
b) Hold-down Displacement Table
New
table has been added giving the components of shearwall displacement for
hold-downs. It is described in the section on deflection output, below.
Shearwalls
now calculates the deflection of each wall segment between openings for each
design case (wind, seismic, rigid, flexible, E->W, W->E). It uses this
deflection to
-
determine
the storey drift, and check that it is within allowable limits for seismic
design
-
distribute
loads to segments within a shearline based on equal deflection of segments
-
determine
rigidities for the rigid diaphragm method of distributing loads to shearwalls.
The
equation implemented is the four-term equation from SDPWS Commentary Eqn.
C4.3.2-1. It is
The
meaning of the variables is given in the following sub-sections. The three-term
equation given in SDPWS 4.3.2, Equation 4.3-1, is not used. According to SDPWS
C4.3.2, the three term equation is a simplification of the four-term equation,
one that does not take into account non-linear nail slippage effects, which
have a significant impact on load distribution when stiffness is used to
distribute loads.
The four
terms in the equation give the contribution to deflection from the following
sources, in order
-
Bending: Bending of vertical shearwall chords (wall
segment end studs)
-
Shear: In-plane shear deformation of sheathing
-
Nail slip: Slippage of nails fastening
sheathing to top and bottom wall plates
-
Hold-downs: Slippage of fasteners connecting
hold-downs to studs, elongation of hold-downs, wood shrinkage and crushing at
hold-down location, and additional displacement due to mis-cuts, gaps, etc.
i. Analysis by Individual Shearwall Segment
For
segmented shearwalls, the unit shear v is vertically accumulated strength-level shear force, that is, the
shear force per unit foot unfactored by the 0.7 load combination factor for
seismic design, as per ASCE 7 12.8-6. For wind design, it is the same as the force
that is used for shearwall design and which appears in the elevation view at
the bottom of the shearwall.
ii. Redundancy Factor ρ
The unit
shear used is the shearline force without the redundancy factor ρ applied.
In some cases, ρ is 1.3 for shearline design, but it remains 1.0 for
deflection analysis, according to ASCE7 12.3.4.1.
iii. Perforated Shearwall Analysis
For
perforated shearwalls, the v used is vmax, that is the force on the
wall per unit distance of full-height-sheathing segment divided by the
perforation factor Co , as per SDPWS 4.3.2.1. Co is given
in SDPWS 4.3.3.5; vmax by Eqn. 4.3-9 in 4.3.6.4.1.1.
iv. Distribution of v Within Wall
The
second and third terms of this equation apply to the sheathing, which can be
different for each side of a composite wall.. Both sides require a shear value
v (the third term does so indirectly through en.). Refer to h) below for an explanation of how shear is
apportioned to each side of a composite wall.
v. Distribution of v to Segments Within Shearlines
The
distribution of v within a shearline depends on the selection of Shearwall Rigidity per Unit Length and Distribute Forces to Wall Segments based on
Rigidity in the Design Settings. For
more details, refer to subsection 3 below
c) Shearwall height h
The
shearwall height h is the distance from the bottom of the bottom wall plate to
the top of the top wall plate, exclusive of floor joists or other building
elements not part of the wall. This height is shown in SDPWS figures 4D and 4E
for segmented and perforated walls, respectively.
d) Segment length b
i. Analysis by Individual Shearwall Segment
For
segmented shearwalls, the length b is the length of an individual full-height
segment between openings, and the calculations are performed for each segment
separately.
ii. Perforated Shearwall Analysis
For
perforated shearwalls, the length b is the sum of the lengths of the
full-height segments, as per SDPWS 4.3.2.1, and one deflection is calculated
for the entire wall.
e) End Chord Bending Deflection
The
first tem in the equation 
relates to the in-plane bending of the
shearwall chords, that is, the wall end studs.
i. Modulus of Elasticity E
An input
field has been added to Shearwalls to allow for input of the grade of the wood
end studs. The modulus of elasticity is then taken from the WoodWorks database
of material properties.
ii. Cross sectional area A
This is
the section area end studs, which are typically built-up members. Shearwalls
now allows you to input wall end stud thickness, width, and number of end studs
(see K.4.b) above ), from which the cross-sectional
area is calculated.
iii. End Post Composition
Shearwalls
does not allow for wall chord posts that are not made up of built-up wall studs
but it is possible to model such a situation by typing in a value for the stud
thickness, as it has no effect on shearwall design. However you cannot change
the wall stud species to the one for the end post without having an effect on
shearwall design, which depends on specific gravity. For MSR/MEL you cannot change the grade without
having an effect on design.
The
second term 
relates to the in-plane shear deformation of
the shearwall
i. Shear Stiffness Gvtv
The
value for shear stiffness Gvtv is taken from SDPWS Table
C4.2.2A for wood structural panels and C4.2.2B for all other materials. The
Sheathing Grades portion of the table is used, in accordance with Note 1 of the
table.
In order
to access table C4.2.2A, inputs have been added to Shearwalls for panel Span
Rating, number of plies, and whether the panel is OSB. These inputs are
described in subsection 6 below.
ii. Shear Value v
Refer to
h) below for an explanation of how shear is
apportioned to each side of a composite wall.
g) Nail Slip Deflection
The
third term 
is related to the slippage of nails
fastening the sheathing to the top and bottom shearwall chords, i.e top and bottom wall plates.
i. Fastener Slip en
The fastener slip en is taken from SDPWS Table C4.2.2D. Note that the slip is non-linear with respect to shear-per-fastener Vn for wood structural panels, but does not depend on v at all for other materials ( it is a constant for gypsum, fiberboard, and lumber sheathing).
ii. Fastener Load Vn
The load per fastener Vn is calculated by dividing the shear-per-unit-length v by the user-input panel edge spacing, yielding the force on each edge fastener.
iii. Shear Value v
The value v used to determine Vn is the strength-level v for seismic design ( see b) above).
Refer to
h) below for an explanation of how shear is
apportioned to each side of a composite wall.
iv. Nails Greater than 10d
The 10d
value is conservatively used for 16d nails, which may be selected for nail
withdrawal strength for wind C&C loads.
v. Maximum Load Per Fastener
The
program does not limit the fastener shear to the maximum in Table C4.2.2D, or
issue a failure warning in this case, as we determined that this level of
loading always results in shearwall design failure for which a failure message
is already output.
vi. Specific Gravity Limitation
SDPWS
Table C4.2.2D indicates that nail slip applies for lumber framing members with
specific gravity of 0.5 or greater. As there is no guidance in SDPWS about what
to do with materials such as S-P-F with specific gravity less than 0.5,
analysis proceeds with the Table C4.2.2D values and a warning note appears
under the Deflection table in the output.
h) Distribution of v to Sides of Composite Wall
For
composite walls, the 2nd and 3rd terms of the
equation, shear and nail slippage, apply separately to each side of the
shearwall, which may have different materials. SDPWS 4.3.3.3.1 provides a way
to apportion the total shear load on the segment to each side of the wall for
the 3-term equation ( see a) above) but offers no guidance on the
4-term equation.
i. Equal Deflections
Shearwalls
apportions shear to each side of the wall by adjusting the v value until the
deflection due to shear plus nail slippage is the same on both sides of the
wall. Note that this equalisation is done regardless of whether equalisation of
deflections for all segments along a line is being done according to the
selection of force distribution design settings described in subsection 3 below.
ii. Zero Shear
Slippage
to non-wood-panel materials is a constant, which in many cases creates a larger
slippage deflection than is possible for shear plus slippage even when all load
is placed on the wood panel. In these cases, all the force is placed on the
wood panel side. The deflection for that segment is the nail slippage plus
shear from the wood panel side, not the
constant
Note
that in this case, despite the fact that all of the load is assigned to the
wood side for purposes of deflection analysis and storey drift, the program
still uses the sheathing on both sides of the shearwall for shearwall capacity
calculations according to the procedures for combining shearwall capacity in
the SDPWS.
The
fourth term in the deflection equation 
relates to the displacement of the shearwall
anchorage devices and the movement of the wood material at the hold-down
location. The following sections give the various components which are added to
give vertical hold-down displacement da.
a) Elongation and Displacement
Refers
to the elongation in tension of the hold-down brackets or straps plus anchor
bolt elongation.
i. Database value
For
those hold-downs with separate elongation and slippage (see K.1.b), the hold-down database contains
the strength-level elongation that occurs at the maximum capacity. For those
hold-downs for combined slippage, the overall strength-level displacement at
maximum capacity comes from the database.
ii. Displacement/Elongation at Maximum Capacity
If this
method ( see K.1.c) above ) is selected for a particular
hold-down, the program uses the database maximum value regardless of the force.
iii. Displacement/Elongation at Actual Force
If this
method is chosen, then the program divides ASD factored hold-down force by the
ASD factored capacity, then multiplies
this ratio by the strength-level displacement/elongation. (ASD capacities are
used because these are needed for hold-down design, however the ratio is the
same as the strength-level ratio.)
iv. Additional bolt length
In some
cases, separate elongation of the anchor bolt is added to the database
deflection. This happens when
-
the Elongation for connector only (without
anchor bolt) hold-down option is selected (see K.1.b)iii above), and the entire anchor bolt is analyzed
separately.
-
This
setting is not selected, but the published displacement or elongation is for an
anchor bolt which is shorter than the one input in Structure input view for the
level the hold-down is on. The elongation for the additional length is
calculated. Note that in this case, for double bracket hold-downs, the
published length is doubled before being compared to the actual length in the
program.
The
elongation of the length L of bolt that is to be analyzed is PL/AE, where A is
the bolt cross-sectional area, E is the
steel modulus = 29000000 psi and P is the strength level hold-down force at
that location.
b) Fastener Slippage
This
value is calculated only for those hold-downs with separate elongation and
slippage. It refers to the vertical slippage of the horizontal fasteners that
connect to the wall studs.
i. Bolts
When
bolts are selected as the hold-down fastener type, the slippage displacement is
given by NDS 10.3.6 as Pf /
(270,000 D1.5), where Pf is the strength level hold-down
force per fastener, and D is the bolt diameter.
ii. Bolt hole tolerance
For
Assembly displacements that include slippage (see 1b, above), any value of bolt
hole tolerance entered in the Hold-down Settings that is greater than 1/16” is
added to the published displacement, which includes the effect of standard size
bolt holes. For separate slippage and elongation, the entire value is added to
the calculated slippage.
iii. Nails
When
nails are selected as the hold-down fastener type, the slippage displacement is
en, from SDPWS Table
C4.2.2D using the values for wood structural panels, and Pf is the strength level
hold-down force per fastener. For
nails greater than 10d, we conservatively use the values for 10d.
iv. Pf
Note
that the value of Pf is arrived at by dividing the uplift force by
the fasteners on just one bracket in a double bracket connection. The same
force P is transmitted to the fasteners in the other bracket.
v. Specific Gravity Limitation
SDPWS
Table C4.2.2D indicates that nail slip applies for lumber framing members with
specific gravity of 0.5 or greater. As there is no guidance in SDPWS about what
to do with materials such as S-P-F with specific gravity less than 0.5,
analysis proceeds with the Table C4.2.2D values and a warning note appears
under the Hold-down Displacement table in the output.
c) Shrinkage
Refers
to the wood shrinkage that occurs between fabrication and service of the
perpendicular-to-grain wood members spanned by the hold-down.
It is
calculated when the hold-down does not include a shrinkage compensating device.
i. Calculation
The
vertical shrinkage displacement is 0.002
x (% fabrication moisture content – %
in-service moisture content) x shrinkage length for that building level
from the Structure input view.
ii. Moisture content input
The fabrication and in-service moisture
content are input in the Design Settings. Previously you could input only
whether it was greater or less than 19%, for use in nail withdrawal design. Now
the actual moisture content is input.
iii. In service Greater then Fabrication
If for
some reason in service moisture content is greater than fabrication, shrinkage
is set to zero.
d) Crush
The wood
crush as input in the Hold-down settings is applied to all hold-down locations
in the program. Typically ranges from 0.2 – 0.4”
e) Additional Components
The
additional components in the “Other – miscuts/gaps” input of the Hold-down
settings are applied to all hold-down locations in the program.
3. Shear Distribution to Wall Segments Within
Shearline
a) Design Settings
The way
that force is distributed with a line depends on the Design Settings Shearwall
Rigidity per Unit Length and Distribute Forces to Wall Segments based on
Rigidity.
i. Distribute Forces to Wall Segments based on
Rigidity
This
setting must be checked to allow the Shearwall
Rigidity per Unit Length choices to affect the distribution within the
line. If it is not checked, the same shearwall force per unit length is applied
to the entire shearline. Deflections in general will be different for each
segment along the line, and the largest deflection is taken to be the one used
for storey drift calculations.
ii. Shearwall Rigidity per Unit Length
This
rigidity is used for both the distribution of applied loads to the shearlines
using the rigid diaphragm method, and for distribution within a line if the Distribute Forces to Wall Segments based on
Rigidity box is checked.
A new
method has been added to the previous
three selections – Use shearwall
deflection to calculate rigidity. If any of the three methods that were in
previous versions of the program are selected, then deflections in general will
be different for each segment along the line, and the largest deflection is
taken to be the one used for storey drift calculations.
b) Equalisation of Deflection
If both
the Distribute Forces to Wall Segments
based on Rigidity box is checked, and the new Use shearwall deflection to calculate rigidity button is selected,
then the program will attempt through an iterative procedure to equalise
deflections on the shearline, by redistributing the shear force v to the
segments until the deflections calculated with Eqn. C4.3.2-1 are the same.
i. SDPWS Reference
This is
the recommended procedure, as it is mandated by SDPWS 4.3.3.4 as a condition
for summing the capacity of walls along a line.
Because
deflection is highly dependent on aspect ratio of the segments, and the
hold-down forces and hold-down devices employed at each segment, deflection can
be highly variable along a line, so that some segments draw negligible force. Furthermore,
some segments have constant components to deflection ( non-wood-panel nail
slip, hold-down overrides, extra hold-down components) that yield a deflection with minimal loading
that is higher than the deflection on other segments even if all the shearline
load was applied to that segment.
If these
situations occur, the program assigns zero load to those segments that are
drawing negligible loads ( less then .1 lb), and equalises the deflection on
the remaining segments. The segment that gets zero force is treated as an
opening or a non-shearwall for the purpose of final hold-down and drag strut
calculations. This segment has no effect on shearwall design: since all
shearwalls must be composed of the same materials (SDPWS 4.3.3.4), the program
finds the most heavily loaded segment for shearwall design.
iii. Non-convergence
The mathematical
system used to model shearwall deflections along a line is not necessarily
determinate. On occasion, the routine is unable to equalise deflections along a
line, oscillating between solutions that do not equalise deflections. In this
case, the deflections that arise from the last iteration before a limit is
reached are used.
If the
design setting Use shearwall deflection
to calculate rigidity is selected, the program determines shearline
rigidity for rigid diaphragm analysis by summing the rigidities of all segments
along the line, where the rigidity is defined as the force on the segment
divided by the deflection of the segment.
If
deflections have also been equalised along the line via Distribute Forces to Wall Segments based on Rigidity, then this is
equivalent to dividing the total force on the line by the deflection.
b) Change to Manual Input
If you
change the setting from Use shearwall
deflection to calculate rigidity to Manual
input of relative rigidity, in order to adjust the rigidities, the
rigidities that appear in the input for a particular wall are the sum of the
rigidities for all segments along the line, divided by the wall length.
For
seismic design only, Shearwalls checks the maximum story drift for any
shearline against the limits in ASCE 7 12.12.1.
a) Cd Factor Input in Site Dialog
The
program now allows input in the Site Dialog for the Deflection Amplification
Factor Cd, given in Table 12.2-1 and used in Eq’n 12.8-15.
i. Default
A
default value appears for the selected Seismic Force Resisting System – Bearing
wall or Building frame, from Table 12.2-1, which can be overridden.
ii. Warning Messages
The
system of warning messages that detects the materials used in the structure and
the Ignore Non-wood-panel… design
settings, and prompts to change the Response Modification Factor R or the
setting, has been modified to include the Cd factor in both the
messages and the resulting changes.
b) Storey Drift Calculation
The
program implements ASCE 7 12.8.6 and Equation 12.8-15 for storey drift
calculations. This calculation is made on each level, and for each force
direction ( E->W, W->E, N->S, S->N).
i. dxe
The
value of dxe is the largest deflection on any shearline, calculated
as described above. If deflections on a line have been equalised (see 4.a) above), it is the common deflection of
all walls on the line. If not, it is the largest deflection for any segment on
the line.
ii. Deflection Amplification Factor Cd
The
values of the deflection amplification factor Cd from the site
dialog are used. Unless they were over-ridden, they are the values from ASCE 7
Table 12.2-1.
iii. Importance Factor I
The
importance factor I calculated from the Occupancy category entered in the sited
dialog is used.
c) Allowable Drift Calculation
The
allowable drift Da calculated according to ASCE 7 Table 12.12-1 is shown for each level
only.
i. Story height
The
storey height hsx for each level is the wall height plus the upper
floor thickness.
ii. Occupancy Category
The
existing input for Occupancy category from the Site dialog is used.
d) Provisions Not Implemented
i. Torsional Amplification
The
program does not implement ASCE 7 12.8.4.3 Amplification
of Accidental Torsional Moment because of the exception for light-frame
structures.
ii. Period for Computing Drift
The
program does not implement 12.8.8.2, which allows the upper limit on the period
to be ignored for the purposes of deflection design. This would have only come
into effect for those users who wished to use a period significantly greater
than the approximate period from Table 12.8-2 for shear design, but not for
deflection.
iii. P-Delta Effects
As
Shearwalls does not currently include full gravity loading, it does not include
P-Delta effects from ASCE 7 12.8-7. It is the responsibility of the designer to
check the stability condition θ. This will be considered for the planned
combined lateral-gravity version of WoodWorks.
e) Output
A new
table has been added showing the storey drift calculations for each level and
force direction on that level, and indicating success or failure of the storey
drift check. Refer to 7.e) below for details.
The
following inputs have been added to access SDPWS Table C4.2.2A for shear
deflection ( 1.f) above).
a) Span rating
The
program allows for selection of span rating in order to access table C4.2.2A
i. Alternative thicknesses
Note
that shearwalls has not added plywood thickness inputs for those thicknesses (
½ , 5/8, and ¾) that are only alternative thicknesses in Table C4.2.2C. The
thicknesses in Shearwalls are minimum thicknesses for shearwall design. You can
type in a different thickness, and the program will use the next smallest
standard thickness for design. This is legitimate for deflection design as
well, as the next smallest primary thickness to the alternative thickness has
the set of possible same span ratings according to Table C4.2.2.C, and those
appear in the span rating drop down when these thicknesses are typed in.
b) OSB
A
checkbox has been added to allow you to specify that the material is OSB as
opposed to plywood, which has different Gvtv values in in
Table C4.2.2A..
c) Number of Plies
You can
now select the number of plywood plies, 3, 4, or 5, which have different Gvtv
values in Table C4.2.2A. This input is disabled for OSB.
a) Shearwalls Materials Table
Because
of the need to add information for deflection design, the shearwalls materials
table has been split into two tables, one for sheathing materials and one for
framing materials.
i. Sheathing materials
-
Material name: The material name has been expanded
somewhat from the abbreviated name in previous versions, but is still not the
full name that appears in the input view.
-
OSB: Whether it is an OSB is appended to the name,
e.g. Struct I OSB
-
Span rating: A column has been added for the span
rating as input in Wall Input view, for structural wood panels only.
-
Gypsum underlay - A column has been added for the
thickness of gypsum underlay, if it has been specified in Wall Input view.
-
Ply – A column has been added for the number of
plywood plies
-
GvTv – A column has been added for the value of Gvtv
from SDPWS table C4.2.2A
-
A
column is added indicating whether nails
are deformed, that is spiral or threaded
ii. Framing materials
For the
framing materials table, only one line is needed for each wall design group,
instead of the two needed for sheathing materials on each side of the wall. The
fields that have been added are
-
Stud grade
-
Stud thickness
b (actual)
-
Stud width d (actual)
-
Modulus of elasticity E, in millions of psi.
A note
has been added below the table saying
Check manufacturer
requirements for stud size, grade, and specific gravity (G) for all shearwall
hold- downs.
b) Storey Information Table
Columns
have been added for the anchor bolt length and the length subject to shrinkage,
as input in the Structure Input view.
c) Hold-down Displacement Table
A table
has been added to show the components of vertical hold-down displacement da due
to the main elongation, displacement, slippage, shrinkage, crush, and
additional sources. It has the following fields.
i. Wall and Segment
The wall
segment between openings is shown as e.g.
B-3, 2 = second segment on Wall 3 on Shearline B.
ii. Force Direction
E->W,
N->S, etc. Can be “Both” if the data is identical in both directions because
forces and hold-downs used are the same. In that case only one line is output
instead of two.
iii. Hold-down
The
hold-down name from the database that is selected at the tension end of the
segment. There is limited space for the name, so it may be truncated.
iv. Uplift Force
The
hold-down force at that location, including force transferred from floors
above, and including the dead, shear and overturning components. For seismic
design it is the sum of the unfactored components for strength-level design.
v. Elong/Disp
This
gives the displacement for hold-downs with combined elongation and slippage,
the elongation otherwise.
-
Manuf
– This is the elongation/displacement for the hold-down with the maximum anchor
bolt length given in the manufacturers literature, or with no bolt contribution
those hold-downs that do not include it (separate slippage, separate
elongation)
-
Add
– This is the elongation additional bolt length in excess of the manufacturer’s
maximum, or the elongation of the entire bolt for those hold-downs that do not
include anchor bolt elongation
-
da
– Vertical displacement due to elongation
= Manuf + Add
vi. Slippage
Data
appear in this column only for those hold-downs for which there is separate
slippage and elongation.
-
Pf – the amount of uplift force P taken by each
fastener in one bracket
-
da – The calculated displacement due to nail or
bolt slippage
vii. Shrinkage da
The
calculated displacement due to wood shrinkage. The moisture contents appear in
the legend below, and the length subject to shrinkage on each level appear in
the Story Information table.
viii. Crush + Extra
The
value of wood crushing plus any additional components entered in the hold-down
settings appears in one column. Although this column usually holds the same
value for all segments, it is possible that at some locations the crush is zero
because there is no compression force at the usual compression end of the
shearwall.
ix. Total da
The total
vertical displacement for each segment, or sum of the elongation, slippage,
shrinkage, crush, and additional displacements, is output in a column.
x. Hold-down deflection
The
resulting horizontal in-plane segment deflection from the hold-downs, or da
multiplied by the segment aspect ratio h/b, is output in a column. This
value is then transferred to the Deflection table.
xi. Legend
The
legend spells out the calculations that are used to arrive at each value,
giving the value of any needed data not in the table such as percent moisture
content and steel modulus of elasticity.
xii. Nail Slippage Note
Because
SDPWS Table C4.2.2D for nail slip applies for lumber framing members with
specific gravity of 0.5 or greater, a warning note appears below the table if
any of the framing members that the hold-downs are connected to have specific
gravity less than 0.5. Note that S-P-F materials have specific gravity less
than 0.5.
d) Deflection Table
i. Wall and Segment
The wall
segment between openings is shown as e.g.
B-3, 2 = second segment on Wall 3 on Shearline B.
ii. Wall Group
The wall
design group
iii. Force Direction
E->W,
N->S, etc. Can be “Both” if the data is identical in both directions because
forces and hold-downs used are the same. In that case only one line is output
instead of two.
iv. Wall Surface
Some of
the columns ( shear deflection and nail slip) have different values for
different sides of the wall. To calculate them, different v values for each
side of the wall are used as well. Therefore for each segment, if it is a
composite wall, there are two lines output.
Wall
surfaces are output as they are in the shear table, as Int or Ext for perimeter
walls, and 1 or 2 for interior walls.
v. Shear v
The
unfactored unit shear value on the segment ( that is, strength level shear for
seismic design) is output. The proportion that goes into each side of the wall
for composite walls is given.
This
value depends on the distribution method input in the Design Settings, and when
deflections are equalised, in many cases it can be zero. See 3.b)ii above.
vi. Segment width b
This is
a full-height segment for segmented walls, or the sum of such segments for
perforated walls.
vii. Wall height h
Although
this does not change for all segments within a level, it is output in a column
as it is integral to the calculations.
viii. Bending
For the
bending component, the following are output on the first of the two lines for
the wall segment:
-
End
stud section area A
-
Resulting
deflection
ix. Shear Deflection
The
calculated shear deflection is output on both lines for the wall segment. The
legend shows the calculation.
x. Nail slip
The
following values are shown for the nail slip:
-
Shear
force per panel edge fastener Vn
-
en
value from SDPWS Table C4.2.2D;
-
Resulting
deflection
xi. Hold-down Deflection
This
value is transferred from the Hold-down Displacement table, where the
components of hold-down displacement are given.
xii. Total Deflection
Deflection
from bending + shear + nail slip + hold-down, as per SDPWS C4.3.2-1.
Note
that shear + nail slip should be the same for both sides of a composite wall,
or else one side has zero force and the shear + nail slip for the other side is
used. If his is not the case because the
numerical procedure failed, the largest shear + nail slip is used.
xiii. Legend
The
legend spells out the calculations that are used to arrive at each value,
giving design code references and where to find data not in this table, e.g.
the Stud modulus of elasticity in the Framing
materials table.
xiv. Nail Slippage Note
Because
SDPWS Table C4.2.2D for nail slip applies for lumber framing members with
specific gravity of 0.5 or greater, a warning note appears below the table if
any of the framing members for the walls have specific gravity less than 0.5.
Note that S-P-F materials have specific gravity less than 0.5.
A table
has been added to the program to show the storey drift calculations ASCE 7
equation 12.8-15 and the allowable storey drift from ASCE 7 Table 12.2-1. The
allowable drift is shown for each level; the maximum storey drift for any
shearwall on the level is shown on one line for each force direction below the
allowable values.
i. Wall height
The wall
height h is shown for each building level, along with the storey height hsx
for that level, which is the wall height plus the upper floor thickness.
ii. Allowable drift
The
allowable drift Da calculated from ASCE 7 Table 12.2-1
is shown for each level only.
iii. Deflection Amplification Factor Cd
The
values of the deflection amplification factor Cd from ASCE 7 Table
12.2-1, for the building system entered in the site dialog, and which can be
overridden in the site dialog, are entered on each line. Note that the Cd values
can be different for different force directions.
iv. Importance Factor I
The
importance factor I calculated from the Occupancy category entered in the sited
dialog. This is the same for the entire structure, but is repeated in the table
to show all variables for a calculation on the same line.
v. Max dxe and Line
For each
force direction on each level, the table shows the largest of the deflections
on any shearline in the force direction, referred to as dxe in ASCE
7, as well as the line the maximum was on.
vi. Max dx
The
program shows the maximum amplified deflection dx, calculated using
ASCE 7 equation 12.8-15.
vii. Failure Message
The
program places an asterisk (*) beside any response ratio that is greater than 1.00.
A note appears below the table as follows
-
One-story structure: If the building has only one level
the note refers to note c of ASCE 7 Table 12.2-1, which says no limit applies
to one-storey structures designed for story drift effects.
-
Multi-story structure: A red failure message
appears.
viii. Legend
A legend
has been added explaining each column in the table.
f) Shear Design Table
i. Seismic Direction
The
program has been change to allow for output of seismic results for each force
direction. Previously this was not needed, as forces were always the same in
both directions. Because hold-downs selected and hold-down forces can vary in
opposite directions, and these affect deflection and thus load distribution,
results can be different in opposing directions.
g) Table Legends
To all
the above tables a legend has been added to the table or an existing legend
improved such that it shows detailed information pertaining to each column on a
separate line.
h) Show Menu and Display Options Toggles
For all
the above tables, items have been added to the Show menu and the Display checkboxes in the Options settings that allow you to turn
off the tables in the screen display and in the printed output, to reduce the
volume of output, similar to all other tables.
i) Elevation View
i. Segment Forces
The
force on each shearwall segment arising from the distribution of forces
described in 3 above are depicted by small arrows at the
top of the wall at each segment, with the force in pounds on that segment
shown.
ii. Shear Flow
The
shear flow depicted at the bottom of elevation view is now much more likely to
show different forces for each segment. This was previously only due to the
perforation wall factor or seismic height to width factor.
C. Shearwall Design Iterations
This
section refers to the iterations needed to design shearwalls for the unknown
values in order to determine certain parameters needed for load generation, load distribution to shearlines,
and force distribution within the shearline, then to go back and redesign based
on the new load distribution.
a) Structural Iteration for r
For
seismic design, the program went through two iterations of designing the entire
structure as follows.
i. Iteration 1
The
program sets the redundancy factor r to 1.3, and designs shearwalls
based on the shearline forces factored by r. .
ii. Iteration 2
The
program recalculates r based on the distribution of shear resisting
elements designed in the first iteration. If it turns out to be 1.0, it
refactors the shearline forces and redesigns the shearwalls based on the new
forces.
iii. Final r calculation
The
program then calculates r based on the final distribution and outputs it
in the Design Results, in the Storey table. It was therefore possible to have a
different r shown
in the design results than was used to calculate the shearwalls. Furthermore,
because this final r would be 1.3, the shearwalls could be under
designed for the actual forces that would be created with the new r value.
In
practice, this occurred very rarely.
b) Rigid Distribution
i. Rigidity based on Shearwall Capacity
The
program designed walls for flexible diaphragm design, and then used the
rigidities based on the capacity of those walls for rigid diaphragm shearwall
design. .
It did not go back and recalculate rigidities
for the new walls designed for rigid design, and continued to show the
flexible-designed shearwall rigidities as the rigidities of the rigid-designed
walls.
ii. Equal Rigidity or Manual Rigidity Entry
For
these distribution methods, the rigidity is independent of shearwall design, so
no iterations were necessary.
c) Distribution within a line
Before
the introduction of deflection analysis, it was possible to determine load
distribution within a line based on relative capacities ahead of time, because
the only things affecting it is the perforation factor and the seismic
height-to-width factor (walls within a line cannot have different materials.)
The
program therefore identified the critical wall for design ahead of time and an
extra design iteration was not needed.
The
program still performs two designs of the structure for the purposes of calculating
rho, however this is now part of a larger design sequence that includes a third
run for final design check.
a) Initial Value
The
value on the initial iteration has been changed to 1.0 from 1.3 for two
reasons:
i. Efficiency
Experience
has shown that the vast majority of buildings have r = 1, so that a second iteration is
not necessary if r is set
to one in most cases..
ii. Design Check
Now that
a third iteration to check the designed walls is done, setting the initial
value to 1 avoids the circumstance that a 1.3 value on the first iteration is
set to 1.0 on the second, during which walls are designed that require r = 1.3 , and loads generated on the
design check run could then cause the walls to fail.
When 1.0
is the initial value, and the second iteration uses 1.3, then walls can be
designed that only require a rho of 1.0. The walls will then be conservative
for loads generated on the third, design check run.
b) Load Distribution
The r value used for rho when only load
distribution, not design, is performed has been changed from 1.3 to 1.0. This
reduces the likelihood of loads for the designed structure differ from those
from on the that previously appeared when loads were distributed for undesigned
walls.
3. Design Iterations Per Level
a) Reasons for New Iterations
i. Stiffness Analysis
Now that
load distribution can be affected by the stiffness due to deflection analysis,
it is no longer possible to predict ahead of time which wall segment will be
critical design, and an iterative procedure is required.
ii. Rigid Analysis
It is an
improvement to the program to redesign walls for rigid analysis based on the
stiffnesses from the rigid analysis. This improvement became especially
important because of the variations in wall rigidity that result from
deflection analysis.
Therefore,
on each level, first for rigid, and then for flexible, the program runs through
two iterations of shearwall design.
b) Iteration1
The
first iteration is used to design
shearwalls to determine rigidities and capacities for load and force
distribution for the second, final design iteration.
i. Distribution to Shearlines
For flexible
analysis, distribution to shearlines is independent of shearwall design, and is
the same for both iterations.
For rigid analysis,
if Shearwalls have equal rigidity or Manual input of relative rigidity is
selected, then the relative rigidity of the shearlines is also independent of
shearwall design, and is calculated by the sum of the wall lengths multiplied
by either 1 or the manual input.
For the other rigid
analysis options (Use shearwall capacity or
Use shearwall rigidity), the
rigidities of the shearwalls designed on the second iteration of flexible design are used as the
rigidities for the first iteration of rigid
design.
ii. Distribution within Line
With
shearline forces established, on the first iteration, for both flexible and
rigid design:
If Distribute forces to wall segments based on
rigidity is not selected, or if Shearwalls have equal rigidity is selected, the program distributes
equal force per unit foot to segments within the line.
If Manual input of relative rigidity is
selected, then the user input rigidities are used to distribute forces to each
shearwall.
Otherwise,
the force is distributed each shearwall using the relative capacities of the
shearwalls, which is based on the perforation and height-to-width factors and
can be determined before the walls are designed. Since walls are not yet designed, the
deflections are not known at this point, and the selection of Use shearwall deflection to calculate
rigidity must use the capacity method on the first iteration.
-
Height to Width Factors – Note that on the first iteration,
the relative capacity of the interior and exterior sheathing is not known, so
the weight of the h/w factor applied to just one side of the wall is not known.
The program applies the height-to-width factor to the whole wall. This results
in a load distribution that can put slightly excess load on the more heavily
loaded walls that do not have a h/w factor. In rare cases, this can result in
an initially conservative shearwall design.
iii. Shearwall Design
With possibly
different forces distributed to each wall, the most heavily loaded wall on the
line is determined, and this is used for to design the shearwall materials for
the entire line. This shearwall design is used to determine rigidities for the
second iteration.
c) Iteration 2
i. Force distribution
If Shearwalls have equal rigidity or Manual input of relative rigidity is
selected, there is no reason for a second iteration, and the program stops at
the first iteration, and delivers design results for the shearwall design for
the first iteration.
Otherwise, using the walls designed with iteration one, the
program determines the force distribution using rigidities derived from either shearwall capacity or deflection analysis, according to the design setting
selected. The force distribution is for distribution of loads to
shearlines using the rigid diaphragm method, and distribution to forces within
shearlines using both methods.
ii. Distribution to Shearlines
The
rigidity of a shearline is estimated using the capacity method by the capacity
of the designed wall on that shearline, in lbs/in, and by the deflection method
by
Σ Fi/DI,
where Fi
and DI, are the forces and deflections on
each segment. If forces are also distributed within the line based on
deflection, so that deflections are equalised, this is just F/D, the total force over the common
deflection. Loads are then distributed to the lines using the torsional rigid
diaphragm method.
iii. Distribution within Shearlines
If the
setting Distribute forces to wall
segments based on rigidity is selected, for both the rigid and flexible
method, then the program calculates the force distribution on the line based on
relative rigidities of segments on the line. Otherwise equal force distribution
is assumed.
If Use shearwall deflection to
calculate rigidity is
selected, then different forces are placed on all full-height segments.
If Use shearwall capacity is selected, the
different forces can be placed on each shearwall. Note that at this stage, the
shearwall capacities are known, so that an estimate based on h/w ratios and
perforation factors is not necessary, the program distributes loads based on
the actual factored capacity of the walls from the last iteration.
iv. Design
With
possibly different forces distributed to each wall using the capacity method,
and each segment using the deflection method, the highest force per unit foot
on any segment on the line is determined, and this is used for to design the
shearwall materials for the entire line. Note that these walls may have
different deflections and possibly capacities than those used to distribute
forces to design the walls; this is dealt with by the Final Design Check, below.
d) Number of Iterations
It would
have been possible to continue this process to further iterations. This was not
done because:
i. Distribution of Shear Forces within Lines
Because
all of the walls on a line must have the same materials, a new distribution
that causes a heavier critical loading will increase the capacity and the
stiffness of all the walls on the line by roughly the same amount. This is
unlikely to cause a markedly different distribution of loads that would require
further iterations.
ii. Distribution of Loads to Shearlines
An
iterative procedure for rigid diaphragm analysis would tend to concentrate
loads on a particular shearline. That is, a heavily loaded line would require
more capacity, would become more stiff, would draw more load, and so on. This
is not a desirable shearwall design for other reasons.
iii. Final Design Check
The
final design check described below now traps and indicates to the user those
rare cases where walls passing on the second iteration failed the final design
check. This was deemed preferable to the increased processing time that would
be needed for all designs if there were more iterations.
iv. Non-convergence
If we
established the condition for ending the iterations that shearwall design did
not change from one iteration to the next, it would be possible for the
procedure to oscillate from one solution to another without ending.
a) Structural Design Check
For the
entire structure, forces are distributed based on the capacities, stiffnesses,
and shear resistance distribution of the walls designed on the second per-level
iteration and the r value
from the second structural iteration, if one was needed.
The
designed walls are then checked against the new forces, and the results
reported in the Design Check output. :
b) Reasons for Check
i. Output Report Consistency
This
ensures that the output reports show the force distribution, the r value, the shearwall deflection, and
shearwall design capacity from the same set of walls.
ii. Possibility of Failure
Although
it rarely occurs, it is possible that the walls designed on the second
iteration cannot withstand the forces created from their rigidities. The design
check shows this situation, indicating to the user via the following warning
message that the problem is to do with design iterations and can be remedied by
more manual input.
Warning:
For shearline(s) [ A, B, C, ..., 1, 2, …], a shearwall that passed the design
check on the initial run failed the final check when forces were redistributed
to shearlines and/or wall segments within a line using [ shearwall deflection,
shearwall capacity]. Try to adjust wall materials to achieve a passing design,
or choose a different force distribution option in the Design Settings.
The new
design iterations in combination with the iterative procedures for equalising
deflections along a line can greatly increase processing time for shearwall
design. The progress bar that appears during design has been updated to
indicate the following
-
The
r value
for each direction for the current structural design loop
-
The
level currently being designed for
-
Whether
flexible or rigid is currently being designed
-
The
design iteration, 1 or 2 on the level..
D. Design Code Updates – SDPWS 2008,
IBC 2009, and ASCE 7-05 Supplement 2
The
program has been updated to comply with the most recent editions of the AWC
Special Provisions for Wind and Seismic (SDPWS 2008), the International
Building Code ( IBC 2009) and the Supplement 2 to the ASCE Minimum Design Loads
for Buildings and other Structures (ASCE 7- 05).
In the
course of this work, certain features that had been omitted from previous
implementations of SDPWS were added to the program, and Wood Frame Construction
Manual (WFFCM 2005) provisions removed, and replaced with SDPWS or NDS
provisions. These changes are noted below.
There is
no longer a choice in the Design Settings of design codes to be implemented by
the program. Formerly, you could choose between UBC, IBC, and SDPWS.
a) SDPWS and IBC
i. SDPWS vs. IBC
ii. The 2009 IBC now references the 2008 SDPWS for
all design procedures, except those using staples, which are not permitted by
SDPWS. Shearwalls does not include staples, so there are no longer differences
between SDPWS and IBC in the program. Therefore the choice between these
procedures has been dropped.
iii. SDPWS Update
In
Shearwalls, the SDPWS has been updated to the 2008 edition from the 2005
edition. Most of the changes in the following sections describe this update.
iv. IBC Update
The IBC has
been updated 2006 to 2009. This involves removing IBC 2006 provisions that are
now handled by reference to SDPWS, and changing reference numbers to those that
remain and are identical to SDPWS.
b) UBC
The design
provisions and load generation procedures from the Uniform Building Code (UBC
1997) are no longer available. To check designs that were made using IBC, it is
necessary to run Shearwalls 8.22 or earlier.
c) WFCM Provisions
The Wood
Frame Construction Manual (WFCM 1995) provisions are now limited to out-of
plane bending values for lumber sheathing materials and one thickness of
plywood (see 9.a)i below). Otherwise, there is no longer
recourse to WFCM if a particular provision is not addressed by IBC or SDPWS.
d) ASCE 7-05
The
program uses ASCE 7 05 for all load generation procedures. It has been updated
for Supplement 2, issued Dec 18, 2007.
The
following refers to references to design codes and design code clauses within
the program Design Results, warnings and instructions that that appear on the
screen, and the help file documentation.
a) Help About, Welcome, Building Codes, and Site
Information Dialog Boxes
i. Building Codes Box
An
explanation of the new design code approach described in the previous section
is given in the Building Code box, which is accessed from the Welcome box,
which can be accessed from the Help menu.
ii. Edition Year
The About WoodWorks Shearwalls, Welcome, and Building Codes dialog now refer to the updated design codes by the
version year. Elsewhere in the program, the version of the design code is not
included.
iii. ASCE
Supplement 2
In these
informational boxes, the references to ASCE 7 say “incl. Supplement 2”.
Elsewhere in the program where ASCE 7 is referred to, the reference to
Supplement 2 is not included.
iv. Site Information Dialog (Change 71)
The
reference to the design code in use has been removed from the Site Information
input screen, as there no longer is any choice in the matter.
b) IBC Provisions
i. Clauses Superseded by SDPWS
References
to provisions that are no longer in the IBC because they have been replaced by
reference to the SDPWS have been removed, and replaced with SDPWS reference if
there was not already a reference to the SDPWS.
ii. Allowable Shear
References
related to allowable shear tables 2306.2 to 2306.7 have been retained, and
appear alongside the equivalent SDPWS references.
iii. Deflection References
IBC
reference pertaining to deflection analysis have not been added to the program,
as these references apply to staples only. The equivalent SDPWS, for all
fastener types, are included instead.
c) AF&PA References (Change 65)
References
to American Forest and Paper Association
and to AF&PA have been removed,
and now refer to American Wood Council
or AWC only, as these organisations
have parted company and only AWC continues the association with WoodWorks. In
particular, the references to the SDPWS refer to AWC only.
d) Help Files
i. Design Code References
Wherever
references to design codes occur, the references have been updated by
-
removing
design provisions no longer in IBC, and replacing with SDPWS if not there
already
-
updating
reference numbers for the SDPWS and remaining IBC references
-
removing
references to AF&PA
-
removing
page numbers
ii. Design Provision Tables
The
tables that appear listing the shearwall design provisions have been updated by
-
removing
the UBC and WFCM columns,
-
removing
design provisions no longer in IBC,
-
updating
reference numbers for the SDPWS and remaining IBC references,
-
removing
references to AF&PA
-
showing
the differences between the 7/8 version of Shearwalls and Shearwalls 9
-
removing
page numbers.
3. Shearwall Materials and Shear Capacities
a) Structural Sheathing and Plywood Siding
i. Shear Design Values
No
changes are made to the shear design values from SDPWS 2005 to 2008 for these
materials. Note that in Shearwalls the wind values are derived by multiplying
the seismic values by 1.4, whereas in SDPWS they are multiplied by 1.4 then
rounded to the nearest 5 plf, so there are slight discrepancies between the
SDPWS values and those in the program.
ii. Specific Gravity Adjustment (Bug 2191)
In
Version 8.x of the software, for the IBC design code option, the equation from
IBC T 2306.4.1 Note was applied to the tabulated values to adjust for specific
gravity. For the SDPWS option, the program was using the values in the specific
gravity ranges from the original WFCM 2005, which can create significantly
different capacities for some framing materials.
The
program has changed to use the equation for specific gravity adjustment, which
is the same equation as in SDPWS Table 4.3A note 3.
iii. Field Nail Spacing Exception
The
exception that allows maximum intermediate framing (field) nail spacing for 24”
stud spacing to be 12” rather than 6” has been removed for 5/16” panels.
Previously the SDPWS listed 3/8” and 7/16” sizes for this exception, but now it
is phrased thicker than 7/16”.
b) Fiberboard
i. Previous Shear Design Values
For
Version 8, the IBC shear design values were the same values that were in the
WFCM – 125 plf for ½” and 175 plf for 5/8” sheathing except that these values were
not multiplied by 1.4 for wind design
because this was not specified in IBC 2306.4.4. These values were independent
of nail spacing choice but dependent on panel thickness. The SDPWS values from Table 3.4A were dependent on nail spacing but not on
panel thickness, and are multiplied by 1.4 for wind design
ii. New Shear Design Values
The
program now implements the values in SPDWS Table 4.3A. The IBC table 2306.6 now
includes identical values, and 2306.3 says to multiply by the 1.4 factor, so
that the program now implements the identical IBC and SDPWS provisions.
iii. Previous Specific Gravity Adjustment
To these
values, a specific gravity factor was applied separately for IBC and SDPWS. Using
IBC 2006 2306.4.1 Note a, it was based gravity ranges. and for SDPWS option,
the equation for specific gravity factor
from Table 4.3A note 3 was applied to the IBC/WFCM data.
iv. New
Specific Gravity Adjustment
The
specific gravity adjustment from SDPWS Table 4.3A note 3 is now the only one
applied. The IBC table 2306.3 now also includes the same equation for nailed
fiberboard.
c) Gypsum and Plaster Materials
i. Gypsum Sheathing Board Maximum Stud Spacing
The
maximum stud spacing for gypsum sheathing board is restricted to 16”, the SDPWS
limit. Previously, for the IBC selection, a spacing of 24” was allowed
according to T2306.4.5.
ii. Shear Capacity
No
changes have been made to shear capacity for these materials except to add the
choice of drywall screws, which have a lower capacity. Refer to 5.f) below.
d) Lumber Sheathing
i. Sheathing Orientation
Previously,
for the IBC setting, only the Diagonal and Double Diagonal orientation choices
were available, as these were the only ones listed in Table 2306.3.3 of the
2006 IBC. For the SPDWS choice, Horizontal and Vertical choices are also
available. With the IBC choice eliminated, all sheathing orientations are
available.
ii. Specific Gravity Adjustment
Previously,
for the IBC choice, a specific gravity adjustment factor was applied based on
the range of specific gravity for the framing material used. There is no longer
a specific gravity factor for lumber sheathing, as SDPWS Table 4.3C does not
include a factor for specific gravity of framing materials.
e) Sheathing Combination Rules
i. Different Materials on Either Side
When
different materials were combined on a wall, except for the combination of
structural materials and gypsum wallboard for wind design, the choice of IBC
meant that the strongest of the two sides was used as the shear capacity, as
per IBC 2006 2305.3.9. The IBC option has been removed, and the program uses
the rule from SDPWS 2008 4.3.3.3.2, that is, strongest or twice weakest.
ii. Gypsum Wallboard and Structural on Same Side
iii. The IBC provisions in Table 2306.4.1 had
never been implemented for the IBC option. Now that similar provisions are in
the SDPWS 2008 Table 4.3B,they have been implemented for Shearwalls 9. Refer to
the following section for a complete description of the feature.
iv. Other Sheathing Combination Rules
Otherwise,
sheathing combination rules were the same for IBC and SDPWS, so no changes are
made to the program by eliminating the IBC option.
The SDPWS
now includes Table 4.3B, for a layer of gypsum wallboard or gypsum sheathing
board under wood structural panels and plywood siding. The program now
implements the fastener choices and shear resistances in that table for this
configuration of materials.
a) Input
A new
combo box labelled Gypsum underlay
has been added to the Wall Input
view, and the corresponding property is saved with the wall definition in the
project file.
i. Choices
The
choices for this box are None, ½”, 5/8”. You
cannot type in a thickness other than the two standard sizes. There is no
“unknown” choice” – you have to specify a configuration.
ii. Applicable Materials
The
combo box is enabled only if the sheathing material selected is Structural I, Structural sheathing or Plywood.
iii. Fastener Sizes
When the
gypsum underlay thickness is changed fastener sizes selection is updated to
account for the available nail sizes for the increased overall thickness of
sheathing.
iv. Fastener Types and Spacing, and Stud Spacing
The
behaviour of the interacting fields regarding nail spacing, stud spacing, etc
is identical as to when there is no gypsum underlay, as per SDWS 4.3.7.2 which
specifies the same construction limitations.
v. Standard Walls
It is
incorporated into the definition of standard walls. This is how you would
specify a default value.
vi. Multiple Wall Selection
It can
be modified for multiple walls selected together similar to all other inputs.
b) Shearwall Design
i. Shear Resistance
When
there is gypsum underlay, the program gets the shear resistance values from
Table 4.3B rather than Table 4.3A. These values do not depend on the choice of
½” or 5/8” gypsum.
ii. Wall Groups
This
property of a shearwall contributes to the distinction of one wall design group
from another, that is, shearwalls with gypsum underlay will be in a separate
design group than an identical wall without it.
iii. Table 4.3B Notes
-
Note
1 is implemented in that we use ½ the published values for ASD design in
Shearwalls.
-
Note
2 for specific gravity adjustment is implemented similar to note 3 in Table
4.3B.
-
Notes
3 and 4 regarding Ga are not implemented, as this is for the
three-term deflection equation in the SDPWS and the program uses the Gvtv
values in the 4-term equation. The effect of moisture on Ga is taken
into account in the wet and dry values of nail slip En used in the 4
–term equation.
-
Note
5 for panels is not echoed under the
Materials table when there are wood panels on both sides of the wall. The
corresponding note for Table 4.3A has never been output. A similar note for
4.7.3.1.4 is output when the conditions are met, both with and without gypsum
underlay.
-
Note
6 (Table 4.3A note 7) regarding galvanised nail production procedures is not
output in Shearwalls.
-
Note
2 in Table 4.3A does not have an equivalent for Table 4.3A and is not
implemented.
iv. Nail Withdrawal Design for Wind C&C Loads
The
increased distance that the fastener must pass through the sheathing before it
penetrates the framing materials is taken into account when determining
withdrawal resistance using NDS Eqn. 11.2.3.
c) Deflection Analysis
The
program does not consider gypsum underlay in deflection calculations; it uses
the shear deformation and nail slip values for the structural wood panel.
Shearwalls uses the four-term equation C4.3.2-1, for which there is no explicit
guidance in SDPWS, but this approach is consistent with one used with the
three-term equation, in that the Ga values used in the combined
shear and nail slip term are the same in Table 4.3A for wood panels as those in
Table 4.3B for wood panels with gypsum underlay.
d) Output
i. Sheathing Materials Table
In the Sheathing Materials table, the thickness
of gypsum is output in a column headed GU
after the thickness of the main shearwall table. The legend explains that
GU means gypsum underlay. A dash appears if there is no underlay.
ii. Table 4.3B Notes
The note
regarding specific gravity adjustment is not changed to refer to Table 4.3B
note 2 instead of Table 4.3A note 1, because it is possible to have a mixture
of walls with and without underlay on the same building.
Note 2
from Table 4.2A is not relevant to walls with gypsum underlay as 7/16 and 15/32
sheathing always have the same shear resistance, so is not included in Table
4.3B. It is not output under the Sheathing Materials table for gypsum underlay.
a) Fasteners - General
i. Reason for Changes
Unless
otherwise noted, the changes to the fastener specifications in the program are
not due to changes in the SDPWS from 2005 to 2008, rather to update the program
to the SDPWS provisions from the previous WFCM and IBC specifications, and to
add new capabilities.
ii. Structural Materials
Changes
to structural sheathing, plywood siding, and fiberboard, are made to comply
with SDPWS Table 4.3A and 4.3B. Unless otherwise noted, these changes have no
effect on shear design, but impact nail withdrawal design for C&C loads
(see 10 below). This effect is discussed in more
detail in that section.
iii. Gypsum materials
Changes
affecting gypsum- and cement-based materials are made to comply with Table
4.3C. Except for the addition of Drywall screws, the do not affect shear
design, and these materials have no nail withdrawal capacity as they are not
expected to be used in exterior applications for wind design. Therefore the
rest of these changes are implemented solely
for a more accurate materials specification.
b) Box Nails for Structural Wood Panels
i. Input
The
program now offers the fastener type choice Galv.
Box nails for Structural I and Structural Sheathing materials, in
addition to the existing Common wire
nails. Note that box nails have not been added for the Lumber Sheathing choice.
ii. Sizes
The same
sizes as common nails are implemented – 6d, 8d, 10d, and 16d.
iii. Diameters
Nail
diameters for use in nail withdrawal design are as given in Table A1, Appendix
A of the SDPWS. They are smaller than common nails of the same length.
iv. Output
Box
nails appear as Box in the Fastener Type column of the Sheathing Materials table. The table
legend refers to SDPWS Table A1 for nail diameters and lengths.
c) Casing Nails for Plywood Siding
i. Common Nails Removed
The
choice of Common wire nails has been
removed for plywood siding, to correspond with SDPWS Table 4.3A.
ii. Casing Nail Input
The
input choice has been changed from Galv.
casing/siding to Galv. casing nails.
iii. Diameters
Nail
diameters for use in nail withdrawal design are the same as for box nails,
given in Table A1, Appendix A of the SDPWS.
iv. Output
Casing
nails now appear as Casing in the Fastener Type column of the Sheathing Materials table, rather than
just Nail. The table legend refers to SDPWS Table A1 for
nail diameters and lengths.
d) Roofing Nails for Fiberboard
i. Common Nails Removed
The
choice of Common wire nails has been
removed for fiberboard, as this choice was taken out of the 2008 SDPWS. It was
in fact the only choice in Shearwalls 8.
ii. Roofing Nail Input
The only
fastener type choice is Galv. roofing
nail.
iii. Sizes
The
sizes 11 ga, 1-1/2” is the only
choice for ½” fiberboard, and 11 ga
1-3/4” for 25/32 fiberboard. .
iv. Diameters
Nail
diameters for use in nail withdrawal design are 0.120 for non-deformed roofing
nails and 0.128 for deformed nails.
v. Nail Spacing
Previously,
the IBC choice for edge nail spacing allowed for only 6” edge spacing. This
choice has been removed, and the program allows only the SDPWS spacings of 4”,
3” and 2”.
vi. Output
Roofing
nails appear as Roof in the Fastener Type column of the Sheathing Materials table. Nail
diameters and lengths now appear in the legend to the table.
The
program now allows you to indicate whether nails are deformed (spiral or
threaded), so that they use the higher deformed nail withdrawal resistance
values.
i. Input
A
checkbox has been added Wall Input View to indicate that a the nails are either
spiral or threaded. It can be modified for multiple walls selected together
similar to all other inputs.
ii. Sheathing and Material Types
This is
available for common wire nails, box nails, casing nails, and roofing nails
used for the structural sheathing, plywood siding, fiberboard, and lumber
sheathing types, that is, all sheathing types that are subject to C&C
loading for nail withdrawal.
iii. Standard Walls and Wall Design Groups
It is
incorporated into the definition of standard walls. This is how you would
specify a default value. It is also a property of a shearwall that contributes
to the distinction of one wall design group from another,
iv. Output
A column
named Df has been added to the Sheathing
materials table, with entries explained in the legend as Y(es) or N(o).
i. Drywall Screw Input
The
choice of Drywall screws has been
added to the program for gypsum wallboard, one-ply only, in addition to the
existing nail choice.
ii. Sizes
The size
No. 6, 1-1/4” appears for drywall
screws.
iii. Shear
capacity
Shear
capacities are implemented as per Table 4.3C.
They are lower than the capacities for drywall or cooler nails.
iv. Output
Drywall
screws nails appear as Screw in the Fastener Type column of the Sheathing Materials table. The size and
length of the screw appears in the legend below the table. .
g) Other Gypsum Wallboard Changes
i. Gypsum Wallboard Nails
The
fastener type for gypsum wallboard has changed from Cooler nails to Cooler/GWB
nails, for both one-ply and two-ply GWB.
ii. Two-ply GWB Sizes
There is
no longer a choice between 6d and 8d for two-ply gypsum, instead the only
choice is 6d base, 8d face, which is
shown in the output as 6/8d, and
explained in the legend.
iii. Two-ply GWB Nail Spacing
There is
no longer a choice between 7”and 9” for two-ply gypsum edge and field spacing,
instead the only choice is 9b/7f which is shown in the output as 9/7.
h) Gypsum Sheathing, Gypsum Lath, and Wire Lath
and Plaster.
i. Nail Sizes in Legend
The nail
lengths and diameters corresponding to 11 ga and 13 ga nails for each of these
materials are now given in the legend.
ii. Wire Lath and Plaster Fastener Type
The
Fastener Type Choice for Wire lath and
plaster has changed to Nails from Screws.
iii. Gypsum Sheathing Board Nail Spacing
7” edge
and field spacing is always allowed. Previously, for the IBC selection, only 4”
spacing was included, as per IBC 2006 T2306.4.5.
iv. 5/8” Gypsum Sheathing Fastener
A note
in the legend now indicates that 6d drywall or cooler nails can also be used
for 5/8 gypsum sheathing, in addition to the 11 ga nail shown in the table.
i) Lumber Sheathing
No
changes have been made for lumber sheathing. Note that box nails have not been
added, despite the fact that they are a choice in the SDPWS.
6. Cub Factor for Unblocked Shearwalls
The
program now implements the new provisions in SDPWS 4.3.3.2 for blocked
structural panel walls.
a) Input
The
program now allows you to select Unblocked
for a wall sides with the following configuration:
i. Sheathing Type
Structural I and Structural
sheathing can now be unblocked. Plywood
siding materials cannot be unblocked.
ii. Panel Edge Spacing
If Unblocked is selected, the panel edge
spacing is limited to 6”.
iii. Wall Height
Unblocked
is unavailable for walls greater than 16’ in height. A wall changed to that
height will cause an unblocked wall to be blocked.
iv. Gypsum Underlay
Structural
sheathing with gypsum underneath cannot be unblocked, as SDWPS 4.3.3.2. refers
to Table 4.3A only, not to table 4.3B for gypsum underlay.
v. Multiple Selection
Changing
the blocking selection for multiple walls is now possible. Previously the
program disabled the selection when multiple walls were selected.
b) Shearwall Capacity
The
program applies the Cub factor from Table 4.3.3.2 based on stud
spacing and intermediate (field) nail spacing to the capacity of the sheathing
on each side of the shearwall independently.
i. Stud Spacing
The 20”
stud spacing option is not implemented for this version of Shearwalls. The Cub
factor is applied for the existing choices of 12, 16 and 24”.
ii. Intermediate Nail Spacing
For
values of intermediate nail spacing between 6 and 12”, the factor for 12”
spacing is used, in other words, the program does not interpolate Table
4.3.3.2.
iii. Design Iterations
The
program
c) Deflection Analysis
SDPWS
4.3.2.2 calls for the unit shear value v in the three-term deflection equation
4.3-1 to be divided by Cub. Equations 4.3.2.2-1,2 show that this is
equivalent to dividing the first two terms in the equation (bending and
combined shear/nail slip) by Cub.
Shearwalls
uses the more accurate 4-term equation from C4.3.2-1, so the program divides
the first 3 terms of the equation (bending, shear, and nail slip) by Cub.
This is the equivalent procedure to that prescribed for the 3-term equation.
Note
that the program does not divide v by Cub in the calculation of en
for the nail slip term. The calculations of hold-down forces used in the 4th
term also do not involve division by Cub.
d) Output
i. Sheathing Materials
A column
has been added to the Sheathing materials to show the underlay thickness to the
right of the main panel thickness. A dash appears if there is no underlay.
ii. Shear Results
For
seismic design, the Cub factor is shared with a column that was
originally for the seismic height-to-width factor for structural materials, but
is now also shared by the fiberboard height-to-width factor. It is now called HW-Cub.
Note
that because unblocked walls are restricted to a H-W ratio of 2, and because fiberboard
does not have a Cub factor, it is impossible to have a combination
of these factors, the factors shown will be one of the three.
For wind
design, the value of Cub for exterior and interior side of a wall is
shown in a similar column that has been added for this and for the fiberboard
height-to-width factor. The low-rise load case has been removed from the table
to make space for it.
iii. Deflection Table
The unit
shear force v shown in the Deflection Table is v divided by Cub. The
force Vn per fastener has not been divided by Cub.
7. Height-to Width Ratios and Factors
a) Fiberboard
The
following changes implement the new requirements in Table 4.3.4 for fiberboard
– that it now is allowed to have a 3.5:1 aspect ratio, where it was previously
limited to 1.5:1, but a penalty is applied to shear resistance for ratios
between 1:1 and 3.5:1.
i. Allow 3.5:1 Height to Width Ratio Setting
The
design group for the Allow 3.5:1
height-to-width ratio setting has been renamed to Seismic wood panels, and fiberboard from Seismic design. If it is checked, then the program allows
fiberboard to be 3.5:1, otherwise it is restricted to 1:1. Previously
fiberboard was always restricted to 1.5:1.
ii. Height-to Width Factor
Separate
factors for wind and seismic design are calculated according to note 3 of Table
4.3.4, and applied to the capacity of a shearwall side that has fiberboard
materials.
iii. Output
For
seismic design, fiberboard height-to-width factors are shown in the same
columns for exterior and interior sides as the structural wood panel height to
width factor, which now also contains the unblocked Cub factor. For
wind design, a similar column has been added to the table, and the column for
low-rise wind case has been removed to make space for it.
The
height-to-width factor is incorporated into the shear resistance that is output
for each side of the shearwall.
iv. Ignore Non-wood-panel Contribution When
Combined with Structural Wood Panels
When we
are allowing 3.5:1 height to width ratios, fiberboard is treated as a
structural wood panel when determining whether to ignore non-wood-panel
contributions, otherwise it is treated as a non-wood panel.
This is
because when fiberboard has a 3.5:1 maximum ratio, there is no advantage to
ignoring it when combined with structural ratio, which as the same h/w ratio.
When it is restricted to 1:1, it is ignored along with gypsum sheathing so that
short segments are not discarded when they can contribute to structural
sheathing capacity.
v. Ignore Non-wood-panel Contribution For All
Walls
An
exception to the above rule takes place when the setting Ignore non-wood-panel
contribution for all walls is checked for seismic design. In this case,
fiberboard is considered a non-wood panel, because the purpose of that setting
is to exclude those materials that might contribute adversely to the value of
the seismic response modification factor R from ASCE 7 Table 12.2-1.
vi. Including Fiberboard Note
vii. A small extension to the … when combined with structural wood panels label called (including
fiberboard) appears after the seismic checkbox, and is disabled and enabled
to show whether fiberboard is considered a structural panel for this purpose .
In most cases, this applies to wind design as well.
b) Unblocked Structural Wood Panels
The
following applies to shearwalls with unblocked structural wood panels on at
least one side. Unblocked shearwalls are new to this version of the program,
see item 6 above.
i. Height-to-Width Ratio
The
program restricts the height-to-width ratio for the new unblocked structural
wood panels to 2:1, in all cases, as per SDPWS Table 4.3.4. Narrower unblocked panels are not considered
full-height segments and do not contribute to shear resistance. Blocked panels
continue to have a H-W ratio of 3.5, with reduced capacity for seismic design
when between 2 and 3.5.
ii. Ignore non-wood-panel Contribution
The
Setting Ignore non-wood when combined
with structural wood panels, does not include unblocked shearwalls among
the structural wood panels. There is no advantage to ignoring gypsum and other
non structural wood materials when combined with unblocked walls, as they have
the same height-to-width ratio.
a) Maximum Perforated Wall Capacity
Shearwalls
imposes the maximum capacity for a perforated shearwalls by replacing the
tabulated value with the maximum value if the tabulated value exceeds the
maximum. The maxima have changed as follows:
i. SDPWS Limit Changed
The
value for a single side of sheathing for seismic design has been changed from
490 plf to 870 plf. The value for both sides combined for wind design has been
changed from 1000 plf to 1217.5 plf.
ii. IBC Limits Removed
The previous
limit for IBC of 490 plf for each sheathing side, from IBC 2006 2305.8.2.1-2, for
wind and seismic, has been removed from the program.
iii. Symbol in Shear Results Table (Change 69)
Previously,
if an interior, exterior or combined shear capacity exceeded the maximum
capacity an exclamation mark was placed in front of the combined shear
capacity in the shear output table. Now,
if the interior and/or exterior sheathing shear capacity exceeds the maximum .
If the combined sheathing capacity exceeds the maximum perforated capacity then
the '!' is now placed after the capacity.
b) Co Factor
The
program continues to use Table 4.3.3.5 to determine the perforation factor Co,
despite the fact that equations 4.3-5 and 4.3-6 have been moved to section
4.3.3.5 from the Commentary. Note that SDPWS offers a choice of using the
equations, based on opening area, and the table, based on segment lengths and
maximum opening height. A future version of Shearwalls will allow for this
choice.
c) Deflection Analysis
The
following SDPWS clauses related to perforated walls and deflection analysis
have been implemented:
i. Shear Value v
For
perforated shearwalls, the v used in equation C4.3.2-1 for shearwall deflection
is vmax given in by Eqn. 4.3-9 in 4.3.6.4.1.1, as per per SDPWS
4.3.2.1., that is, v divided by the
perforation factor Co.
ii. Shearwall Model
For
perforated shearwalls, the length b is the sum of the lengths of the
full-height segments, as per SDPWS 4.3.2.1, and one deflection is calculated
for the entire wall.
9. Out-of-plane Bending Design for C&C Loads
This
section pertains to the allowable loads in psf for out-of-plane bending design
of sheathing members subject to component and cladding wind loads.
a) Previous versions
For all
previous versions of Shearwalls, design values were taken from Table 7A of the Wood
Frame Construction Manual if they were close to those in the SDPWS, when
factored as explained below.
ii. Values from SDPWS
Two
anomalous values were taken from the SDPWS -
12” spacing, perpendicular to the supports, 19/32"and 23/32"
thicknesses. These anomolies were due the fact that SDPWS included shear
effects in the analysis as well as bending.
iii. Wind Load Duration Factor
The
values in the WFCM table are unfactored for load duration, and a footnote says
they can be multiplied by 1.6 for wind design.
iv. ASD Design
The
values were published as Allowable Stress Design (ASD) values, so no conversion
was necessary for Shearwalls ASD design.
v. Span Assumption
The
values assume the sheathing is supported in 3 spans by the studs.
b) Version 9
i. Values from SDPWS
For all
but the cases given below, the design
values are now taken from SDPWS Table 3.21.
ii. Values from WFCM
Values
for lumber sheathing are taken from the WFCM 2001, as SDPWS does not list these
values. Values for 5/16” sheathing are taken from the 1995 WFCM as they are in
neither the SDPWS nor the 2001 WFCM.
iii. Wind Load Duration Factor
The
SDPWS values incorporate a wind load duration value of 1.6. In Shearwalls, the
values are multiplied by the ratio between the user-input load duration value
from the Design Settings and 1.6. (Note that NDS Table 2.3.2 refers to 1.6 as a
“frequently used load duration factor”, indicating there is some latitude for
designers to change this value, hence the override in Shearwalls)
WFCM values
for 5/16 plywood are multiplied by the user-input load duration factor.
Lumber
sheathing values from the WFCM are multiplied by the 1.4 factor given in WFCM
table 4A, multiplied by the ratio of between the user-input load duration
factor and the standard load duration factor of 1.6.
iv. ASD Design
The
values are divided by 1.6 for ASD design in Shearwalls, in accordance with
SDPWS 3.2.1.
c) Out-of-Plane Sheathing Assumption
The WFCM
values were based upon the assumption of two span stud support, the SDPWS is
based on three spans. Refer to SDPWS C3.2 for the reason for this change.
The
program now allows you to select which assumption you prefer based on the
characteristics of your building.
i. Input
Radio
buttons 2-span and 3-span have been added to a new data
group called Out-of-plane sheathing
assumption in the Design settings.
ii. Default Value
The
default value for new files is 2-span, in accordance with SDPWS. The value for
existing files from previous versions is 3-span, so as to retain the design
results for those files.
iii. Calculation
When
3-span is selected, the factored tabulated values are multiplied by 1.25.
iv. Output
The span
assumption appears below in the legend below the Components and Cladding by Shearline table.
10. Nail Withdrawal Design for C&C Loads
a) Withdrawal Calculation
The
program no longer implements WFCM 1995 Supplement Table 7A for nail withdrawal
design values, and now uses NDS Eqn. 11.2-3 and Table 10.3.1
W = 1380 CD
CM CT G2.5 D
where W
is the capacity per nail G is the specific gravity of the framing material, and
D is the nail shank diameter, CD is the load duration factor, CM
the wet service factor, and CT the temperature factor.
i. Nail Diameters
For box
and common wire nails, nail diameters used are those given in Table A1 of SDPWS
Appendix A. Casing nails have the same diameter as box nails of the same size.
Roofing nails for fiberboard have a 0.120” diameter given in Table 4.3A.
ii. Specific Gravity G
The
specific gravity is determined by the existing inputs in the program for
framing material species and, for MSR/MEL, grade as well. Previously, specific
gravity was taken into account by WFCM by using publishing separate values for
3 ranges of specific gravity. The new procedure provides a continuous variation
of W with respect to G.
iii. Load Duration Factor CD
The load
duration factor CD as input in the Design Settings is applied to the
equation. Previously, the WFCM table included a 1.6 factor, and the values were
adjusted for the difference between the input value and 1.6.
iv. Service Factors CM and CT
The
factors CM and CT were already being applied to the WFCM
values using NDS Tables 10.3.4 and 10.3.3, and the inputs for moisture content
and temperature in the Design Settings.
b) Deformed Nails
The
program now allows you to indicate whether nails are deformed (spiral or
threaded – see 5.e) above), so that they use the higher
deformed nail withdrawal resistance values.
i. Nail Withdrawal Capacity
The
values used are derived from NDS Eqn. 11.2-3, using a diameter one size larger
among the list of diameters in table 11.2C than the actual nail diameter. This
is the procedure AWC used to generate the threaded nail values in Table 11.2-C.
ii. Roofing Nails for Fiberboard
Although
roofing nails are not included in Table 11.2-C, the same procedure was adopted
and the withdrawal value for 0.131” diameter nails is used for 0.120” roofing
nails. 0.131 was chosen because the value for threaded nails in 11.2C shows 82
for .012, which is the value for 0.131 diameter unthreaded nails. This was
confirmed with AWC to be correct.
a) Hold-down Table Note for Washers
The note
that appears under the Hold-down Design Table regarding the anchor bolts
washers has been changed to refer to SDPWS 4.3.6.4.3 and 4.4.1.6 rather than IBC 2305.3.11. This involved a
slight change in wording of the note.
The ASCE
7-05 Minimum Design Loads for Buildings and Other Structures, used for all wind
and seismic load generation procedures, has been updated for Supplement 2,
issued Dec 18, 2007.
a) Minimum Seismic Response Co-efficient Cs
The
minimum value of the seismic response co-efficient Cs has been
changed from 0.1 to the maximum of 0.1 and .044 I Sds . In the
change from ASCE 7-02 to ASCE-7 05 it had changed from .044 I Sds to
0.1, evidently what was intended was that both limits be maintained.
b) References
The
reference to Supplement 2 is made in the informational dialog boxes Welcome, Help/About, and Building Codes,
but not in any other references to ASCE 7.
The
following are changes not related to the addition of hold-down connections,
deflection analysis, new design iterations, or design code updates described in
the previous sections.
a) Window Bars
The bars
that appear at the top of the Plan View, Elevation View, and Design Results
View have been modified as follows
i. Settings
The Settings… item has been removed to the
right of the bar, in order that items that refer to the operation of the window
appear first.
ii. Hold-down and Log File Items (Change 68)
iii. The button Hold-downs
has been added to invoke the Hold-down database editor, and the button Log File has been added to open the Log
File. These appear to the right of the bar.
iv. Ellipses Removed (Change 60)
Ellipses
(…) have been removed from those items that do not lead to a dialog box
appearing – Show, View, Preview, Wide
View.
v. Starting Out
The
button that was called “Help” that invoked the “Getting Started with
Shearwalls” box has been renamed Getting
Started…
a) Getting Started with Shearwalls
This box
has been updated to
-
better
describe the sequence of program operations, for example creating openings for
all levels before extending walls.
-
describe
more fully the purpose of blocks as eventual roof shapes
-
better
indicate how to perform key operations, such as the shift-key wall move and
navigating within the design results output
-
add
the Load Input, Design, and Design Results steps to complete the process
-
include
information about hold-down connections and deflection analysis
b) Structure Dialog
i. Status Bar Messages (Change 59)
Status
bar messages have been added to explain the use of each of the input fields in
the box.
c) Wall Input View
i. Default Sheathing Orientation
The
default sheathing orientation for standard walls has been changed from vertical
to horizontal sheathing.
ii. Fastener and Stud Spacing Updates
The
system for updating fastener and stud spacings in the program did not always
provide the correct choices according to design code rules. This was reviewed
and several refinements were made, so that we are confident that the correct
choice of fasteners appears. The changes in the user interface are mirrored in
the choices that are available to the design engine. Some of the more evident
changes are
-
Stud spacing : In many instances, 24 stud spacing
was not available, when it should have been.
iii. Update of Fasteners Size
The
program no longer attempts to maintain a fastener size selection from a
previously selected material if that fastener size is not one of the standard
selections for the material. It retains the selection when going from
Structural 1 to Structural Sheathing, and vice versa, but otherwise it restores
the default selection, which is the first in the list.
iv. Both Sides Same for Sheathing Thickness and
Orientation (Change 74)
After
checking the checkbox that indicates both exterior and interior surfaces have
the same sheathing materials specification, and making changes to the sheathing
thickness or orientation, the sheathing on the opposite side to the one you
were editing before you checked the box was not being updated for the changed
property. This results in walls that are supposed to have the same sheathing on
either side not being treated as such in the design engine. If the sheathing
also has unknowns, it is possible for the design engine not to design the
interior side (Side 2), outputting question marks in place of materials specifications
and zero design capacity.
d) Site Dialog - Seismic Force Resisting System
i. Bearing Wall vs. Building Frame Input
An input
has been added to specify whether Building Frame or Bearing Wall systems are
used to determine the value of the response modification factor R and the
seismic amplification factor Cd from ASCE 7 Table 12.2-1.
ii. Default Value
The
default value for new files is Bearing
Wall system.
iii. Previous Versions
For
projects from previous version, the program detects which system is in use via
the value of R.
iv. Override
It is
possible to over-ride this choice via the R and Cd inputs, in
particular to employ one system in one direction and the other in a
perpendicular direction.
e) Settings
i. Shear Distribution within Shearline
In the
Design Settings, the setting Design shear force based on wall rigidity has been
renamed Distribute forces to wall segments based on rigidity.
ii. Default Floor Depth
In the Default Settings, the setting Floor
joist depth (in) has been renamed Floor depth (in), because the depth includes flooring materials as
well as the joist depth.
iii. Default Wall Thickness
In the Default Settings, the Wall thickness has been changed to Wall display thickness, to emphasize
that the input affects only the drawing on the screen, and not the actual
thickness of the wall studs used for hold-down deflection analysis. The default
for that purpose is set via the stud size in the default Standard Wall.
a) Gridline Snap Increment Setting (Bug 2188)
Changing
the Mouse click interval in the View
Settings causes the Display Gridlines
every __ snap increments to change
automatically when exiting the box in order to maintain the same gridline
display distance as before the changes. However, it did so even if the you had
changed the Display gridline”
manually. Now, the program checks if it has been changed manually before
automatically adjusting.
b) Crash on Loads and Forces Setting (Bug 2194)
When
ASCE 7 low-rise was chosen as the Wind
Load Design Code in the Design
settings, the program would crash when the Loads
and Forces tab of the Settings is
invoked. This has been corrected.
c) Default Shearline Elevation Offset (Bug 2198)
The
default shearline elevation offset has been set to 1 joist depth from 0.5 joist
depths.
1/2 of
the default 10" joist depth is less than the default plan offset of
6", so that a shearwall on a multi-storey building that was within the
plan offset or another would nonetheless
be placed on a different shearline, so that it complied with the elevation
offset with walls on the level above. For example, a wall offset 6" on the
floor below, but not above, would be placed on its own shearline.
The
problem was exacerbated by the fact that 1/2 the default joist depth was less
than the default snap increment, and walls must be created at least one snap
increment apart. Therefore this problem would occur in every case for users
using the default shearwalls settings.
a) Seismic Design Category Restrictions (Change 62)
The
limitations on seismic design categories that materials can be used for given
in IBC Table 2306.7 note a, referring to ASCE 7 12.2-1 and in SPDWS 4.3.7.5 for
gypsum wallboard and other gypsum or plaster materials, SDPWS 4.3.7.4 for
fiberboard, and SDPWS 4.3.7.6-9 for lumber sheathing, are now imposed by
setting the shear capacity for those materials to zero if it is a prohibited
seismic design category.
Previously
the program merely warned the user on the screen that prohibited materials were
being used, and placed a message under the Seismic Information table, but went
ahead and allowed you to design for these materials anyway. No message appeared
under the shear results table. Notes now appear under the Sheathing Materials table, the Seismic
Information table, and the Shear
Design table. Refer to 6.a) below for more details .
b) Seismic Height-to-Width Factor
i. Design Shear based on Rigidity with Seismic
Factor (Bug 2187)
When the
Distribute forces to wall segments based
on rigidity option was selected in conjunction with the Use shearwall capacity to approximate
rigidity option, the design shear distributed to each segment was not
taking into account the seismic height-width factor from SDPWS.
This
resulted in walls with H-W factors less than one to be given more design shear
than they should have been, and the other walls on the shearline received less
design shear than they should have. Since the program designs for the walls
with the low height-to-width factor, this created conservative designs.
ii. Combining Seismic Height-to-width Factor (Bug
2190)
When
there was more than one full-height segment on a wall, the program was using
the weighted average of combined height-to-width factor of all the individual
segments’ height-to-width factors, instead of the minimum height-to-width
factor of any segment in the shearwall.
This resulted in the design wall for a shearline using a larger
height-to width factor than it should have, and non-conservative design.
This
also affected the calculation of redundancy factor ρ, when checking
whether on walls resistance is greater than 35% of resistance of the
story.
5. Load and Force Generation and Distribution
a) Wall Wind Loads
i. Vertical
Location of Upper Wall Load (Bug 2107)
The
bottom of generated wind area loads on the upper portion of walls was not
midway up the wall, instead midway plus ½ the floor depth. This created a
higher z-value used for the evaluation of the exposure coefficient Kz and the
topographic factor Kzt. The effect was conservative and small, creating wind
loads at most 3% too heavy.
ii. Area Load Tributary Width and Magnitude
Reporting (Bug 2108)
Automatically
generated area loads on the lower half of walls are given a vertical tributary
width that is derived from the upper half of the storey, so it includes the
joist depth of the storey above when it shouldn’t. These incorrect widths are
shown in the load lists in the load input screen and Design Results.
The
incorrect width is used in creating the load intensity shown in these lists, so
that the total load on the wall segment remains the same as if the correct
tributary width was used. The line load created on the diaphragm and shown in
plan view is also correct, so this problem has no impact on force generation or
design.
b) Redundancy Factor ρ with User-applied
Seismic Loads (Bug 2189)
The
redundancy (ρ) factor calculations for ASCE 12.3.4.2 were not including the
user-applied loads and shearline forces in its base shear calculations. This
caused the rho factor to be more likely to be set to 1.3 instead of 1.0 in this
case, possibly causing conservative forces to be created.
Now, the
user applied loads and shearline forces are added to the base shear determined
by the load generation procedure. As user-applied shearline forces are
factored, these forces are first unfactored before being added to the base
shear.
c) Anchorage Forces t
i. Anchorage Forces above Openings (Bug 2192)
For version
8.21 of the software only, the anchorage force t for perforated walls from
SDPWS 4.3.6.4.1 was not creating anchorage hold-down forces at the opening ends
for that portion of an anchorage force that is distributed from an upper storey
wall to an opening on the lower story.
ii. Anchorage Force t for Seismic Design (Bug 2193)
The
anchorage force uplift (t) that is created for perforated walls as per SDPWS
4.3.6.4.1 was twice as large as it should be for seismic design. This also
sometimes created uplift (t) point load hold-down forces that were twice as
large as they should be.
d) Response Modification Factor R
i. Warning Message for Wood Panels Combined with
Non-wood (Bug 2196)
Upon
generating loads, the program issues a warning if you have selected a response
modification factor R for a particular direction that is not the one for the
building system in use, according ASCE 7 12.2-1, for example if a value of 6.5
is used in the presence of gypsum wallboard which should have an R value of
2.5. According to the response, the program changes the R value to the
appropriate one, or sets the “Ignore non-wood panels for all walls” setting, or
cancels load generation.
In
making this warning, the program considers the effect of the setting “Ignore
non-wood-panel contribution for all walls”, that is, if it is set, it does not
issue the warning and allows the higher value of R. However, it was not considering the effect of
the Ignore non-wood panels when combined
with structural wood panels setting, in the case that the gypsum materials
were always combined with wood panels in the direction in question. In these
cases it used to issue the warning and impose the lower value of R, but now the
warning does not appear and the higher value of R is allowed.
Similarly,
the program failed to deliver a message that a higher R value was possible when
the R value was set to 2.5, but could be 6.5 for this reason.
Note
that in these cases, the correct behaviour could have been achieved by setting
the Ignore .. for all walls, setting,
which is equivalent to Ignore … when combined.. setting when
there are no walls that are totally non-wood-panels ( e.g. gypsum on both
sides).
ii. Default Response Modification Factor (Change
59)
The
default response modification factor R that comes with new installations of
Shearwalls now has a response modification factor of 2.0 rather than 6.5. This
is because the default standard walls that come with Shearwalls have gypsum
materials. Previously, the default was 6.5, which caused a warning message to
appear for load generation with the default Shearwalls configuration.
a) Sheathing Materials Table Notes
i. Note 4 - Seismic Design Category Restrictions
If one
or more materials in the table are disqualified and shear capacity set to zero
due to seismic design category restrictions described in 4.a) above, a Note 4 appears below the table,
and the number 4 appears in the Apply notes column to the table. The SDPWS
design clause is given for each material in the table that is disallowed. This
note appears only if there are seismic loads on the structure.
ii. Notes 5- 7 – Ignore Non-wood-panel Contribution
The
effect of the design settings “Ignore non-wood panel contribution…” , “for all
walls” and “when combined with structural wood panels”, is now indicated in
notes under the Sheathing Materials table. If the capacity of a sheathing side
for a wall group is set to zero for this reason, then the program places a note
number in the Apply Notes for that material, referring to the note below the
table.
-
Note
5: This note is for ignoring non-wood panels for all walls for seismic design.
-
Note
6: This note is for ignoring non-wood panels when combined with structural wood
materials for wind design.
-
Note
7: This note is for ignoring non-wood panels when combined with structural wood
materials for seismic design.
iii. Missing Note 2 ( Bug 2063)
If notes
1, 2 and 3 all pertained to a particular sheathing side, occasionally note 2,
referring to special nailing requirements for certain panels from SDPES
4.7.1.4, and previously IBC Table 2306.4.1 Note b, would not appear below the
table. This has been fixed.
b) Seismic Information
i. Seismic
Design Category Restrictions
Under
the Seismic Information table, in a new section called Seismic Zone Restrictions, a note gives the materials that have
been disqualified due to seismic zone restrictions and directs you to the Sheathing Materials table for the
specific wall groups. Previously a
more general note appeared immediately below the table.
ii. Effect of Ignore Non-wood-panel Contribution on
Seismic Information Warning (Bug 2183)
When the
design settings "Ignore non-wood panel contribution when combined with
structural wood panels for seismic" was set then the warning below the
Seismic Information table regarding seismi c zone restrictions could be output
when it shouldn't have been. This has been corrected.
iii. Vertical Earthquake Load Note
The note
explaining the derivation of the vertical earthquake load no longer appears
immediately below the table; instead it is in a separate section called Vertical Earthquke Load Ev. It was
causing some confusion in that it did not refer to anything in the table.
iv. Redundancy Factor
The
“Reliability Factor” in the Seismic Information table has been renamed
“Redundancy Factor”, to accord with the terminology in the ASCE 7, rather than
the obsolete UBC code.
c) Design Results Tables – General
i. Design Case in Heading
At the
top of each table, and at the top of each page of results for each table, the
design case is now given in brackets, e.g.
(rigid wind design). Previously this just appeared at the top of new pages
in the Shear Results table.
ii. ASD Forces
The
abbreviation ASD has been added to
forces such as shearline forces v and hold-down forces, to emphasize that these
forces have been factored for allowable strength design, and to distinguish
from forces used for deflection analysis, which uses strength-level forces. It
has also been added to the Design Settings table when referring to load
combination factors.
d) Shear Results Table
i. Load Case for Wind Design
In the
Shear results table for wind design, the Load Case column that once showed the
critical low-rise load corner and transverse vs longitudinal load case, has
been removed to make room for fiberboard height-to-width factor. The load case
information is available in the Log File.
ii. Perforated Wall Collector Shear vmax (Change 72)
For
walls with one shearwall on multi-story shearlines, or on single-story
shearlines when there were also non-shearwalls, the program was outputting a
dash (-) instead of the vmax value for that wall. This has been
corrected and the vmax value is shown.
iii. Seismic Design Category Restrictions
If any
of the wall groups listed in the table do not have shear resistance on at least
one side due to seismic zone restrictions, a new note under the Seismic Shear Results table informs you
that shear capacity is zero, and directs you to Sheathing Materials table to
find out which were the offending groups.
iv. Ignore Non-wood Panel Contribution
If the
contribution to shear capacity has been ignored due to the Ignore non-wood-panel contribution… settings, then a note now
appears under the shear results table, referring you to the Sheathing Materials
table to find out which wall groups were affected. .
e) Components and Cladding Table
i. Gypsum Sheathing (Change 73)
The
program was reporting a nail withdrawal capacity for gypsum sheathing, when it
should have considered this material one with no capacity for wind C&C
design.
ii. No Capacity Message (Change 73)
When a
material such as gypsum wallboard that has no sheathing capacity was used on an
exterior surface, the program was outputting a warning note saying it failed
the withdrawal capacity check, and another saying that the material on the
exterior has no shear capacity. Only the second note, about no shear capacity,
is output now.
f) Table Legends and Notes
i. Separate Lines
The
following legends have been broken into separate lines for each item for
enhanced readability:
-
Sheathing
Materials
-
Framing
Materials
-
Shear
Results
-
Hold-down
Design
-
Drag
Struts
ii. Additional Information
The
following legends have been improved:
-
Sheathing
Materials
-
Framing
Materials
-
Shear
Results
-
Hold-down
Design
-
Drag
Struts
Among the
more common improvements are
-
Adding
descriptions for table rows and columns that previously did not have one
-
Integrating
notes into the legend, and eliminating duplication of information in notes and
legend
-
Adding
design code clause references
-
Updating
design code references to SDPWS 2008, and eliminating obsolete IBC references
-
Adding
“ASD” when referring to factors or factoring
-
Changing
terminology to match exactly that in the design code
-
Referencing
other tables when necessary.
iii. Legend-Note Separation
A blank
line has been inserted between the legend and the notes for all tables, for
better readability.
iv. Failure Messages (Change 70)
Any
warning message indicating design failure in any way is now in red type. For
example nail withdrawal design warnings
g) Log File
i. Log File Closing ( Change 75)
The
program now automatically closes the log file when a document is closed.
Previously the log file remained open even if Shearwalls was exited. This
occasionally caused program crashes when a log file remained open for a file
that was then reopened.
|
|
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Shearwalls 8.21
– Feb 12, 2010 - Design Office 8, Service Release 3
This
version was released to correct the following problem that was introduced in
version 8.2
1. Framing
Material and Species Input (Bug 2114)
When
the framing material or species was changed In the Wall Input form, the program did not record the change, instead
reverting to the default value the next time that input field was accessed, or
when the building was designed.
As
a result, the calculation for shear capacity always used the density value for Douglas fir, which according to SDPWS
Table 4.3A Note 4 (wood-based panels) and IBC Table 2306.4.1 Nota a (wood panels) and 2306.4.4 (
fibreboard) is as much as 14% stronger
than that for other materials.
Note
that Southern Pine framing materials are
not affected in terms of strength,
but the desired material
specification would not appear in the Design Results output.
In
addition, this problem precluded the use of MSR and MEL materials, or any
custom materials you enter in Database Editor.
It
was still possible to change your framing material and species specification
via standard walls – you first create a standard wall, select the desired
materials, and then select the standard wall as your shearline wall.
2. Response Modification Factor R Changes
a) R for Bearing Wall Systems on Change Prompt
(Bug 2127)
Upon
detecting non-wood-panel materials the program would prompts you user to change
the input Response Modification Factor R to 2.5 from the value appropriate to
wood panels, and indicated in the warning message that this is the value for
bearing wall systems. However, 2.5 is the value for building frame systems, the
correct value for bearing wall systems is 2.0, from ASCE 7 table 12-2-1. The program now changes the value to the
correct one for bearing wall systems, 2.0.
b) Detection of Structural System for R (Change
57)
When the
program prompts the user to change response modification factor R based on
whether non-wood-structural panels exist and whether the Ignore Non-wood-panel Materials design
setting is set, it now chooses a value for the building system it detects from
the previously input value. For example the existing value is 2.0, it prompts
you to change to 6.5, the value for bearing wall systems, and it refers to ASCE 7 Table 12-2-1 A14 and A13,
respectively. If 7.0 is set, and there
are active gypsum materials, it prompts you to change to 2.5, the value for
building frame systems, referring to A24 and A23. Previously the program assumed bearing wall
systems when it made the change. Bearing wall systems is still assumed if a
value other than 2.0, 2.5, 6.5, or 7.0 is the existing input.
c) Update of R in Site Dialog (Bug 2128)
When SDPWS is set as the Design code in the Design
Settings, the program mistakenly set 6.0 as the response modification
factor in the Site Dialog, rather than the correct 6.5 for bearing wall systems
with wood panels, A13 from ASCE 7 table 12-2-1.
3. Crash with Projects Created in Version 2004
(Bug 2122)
Projects
originally created with 2004 often crashed with Shearwalls 8.2 to when a wall
was selected, when it was deleted, or when a project was closed. It was
possible to open the file, save it with version 8.2, close it, and reopen to
avoid this problem.
The
following changes were also made:
4. Relative Rigidity for Standard Walls (Bug 2120)
When the Shearwall Rigidity design setting is not
Manual input, the program now allows
the input of a relative rigidity for Standard Walls. It can then be used on
walls created from those standard walls for projects with different rigidity
settings, or if you change the rigidity setting in the same project. Previously,
it the program disabled the rigidity input, and displayed the same for
standard walls as it does for regular walls, that is to show “1.00 (Wind
design)” and assign a value of 1.0.
5. Name Field for Standard Walls (Bug 2119)
The
Name input for Standard Walls was
widened to coincide with the length of the wall names in the dropdown list.
Shearwalls 8.2 – November 23, 2009
This version of Shearwalls was issued to provide
the following corrections and enhancements to Shearwalls 8.1. It was released as a Stand-alone Shearwalls
and as part of Design Office 8, Service Release 2.
1. Ignore Non-wood-panel
Materials for Seismic Design, All Walls (Bug 2034)
a) Ignore Non-wood-panel Setting
for High R Values and Walls with No Wood Panels*
In Version 8.1, The program prompts the you to
continue design with loads generated with response modification factor R
greater than or equal to 6.5 or 7 appropriate to all-wood design, but to
disable non-wood-panel contribution to shear resistance (i.e. contribution from gypsum, fibreboard, and
lumber sheathing). (The building frame
system employed determines the choice of 6.5 or 7, according to ASCE 7 table
12.2-1).
However, the design setting invoked by this message
only disabled the contribution for non-wood-panels that are combined with wood
on the other side. For those walls with non-wood-panels on both sides, the
program should have been designing with loads generated with R = 2 or 2.5,
which are heavier than R = 6.5 or 7 loads, thus the design was non-conservative
for these structures when this message prompt was accepted.
b) Ignore
Non-wood-panel Contribution to Seismic Design of All Walls Setting
To solve this problem, a setting was added to the
design settings to ignore gypsum, fibreboard, and lumber sheathing entirely for
seismic design, and that setting is invoked if you respond “yes” to the message
prompt.
Refer to the Input section below for more details on the setting
added, and related changes to the settings that allow you to ignore
non-wood-panels in various circumstances.
c) Existing Projects
You
should check existing projects created with previous versions to ensure that the loads in these files were
generated with the correct R value. If loads were generated with an R value of
6.5 or 7, then you must either check the Ignore
non wood for all walls setting or regenerate loads with the lower R value
of 2 or 2.5.
d) Message Nomenclature
In the
message prompt, the nomenclature “non-wood shearwalls” is changed to
“shearwalls that are not sheathed with structural wood panels” in recognition
that the materials that are to be ignored when this is checked include lumber
sheathing and to emphasise the terminology used in the design codes.
e) Load Distribution and Shearline Design on Walls
with no Shearwall Capacity
With the
addition the Ignore non-wood-panel
contribution to seismic design for All
walls setting, it is now possible to have entire shearwalls and entire
shearlines with a sheathing capacity of zero. In these cases, these shearwalls
are treated as non-shearwalls or non-shearlines. The consequences are discussed
in detail in the section on Load Distribution, below
2. Ignore
Non-wood-panels When Combined with Wood for Wind Design (Bug Bug 2035)
Previously,
the “Ignore non-wood when combined with wood” setting applied to seismic only,
when it should apply separately to wind design.
a) Background
and Rationale
The
height-to-width limits are found in SDPWS table 4.3.4 and IBC Table 2306.3.4.
The limit for non-wood-panels (gypsum, fibreboard, lumber sheathing) is 2, for
structural wood panels it is 3.5.
The
reason this setting is to allow full height segments with height-to-width
ratios between 2 and 3.5 when they have non-wood-panels on one side and
structural panels on the other.
The
design code tables are specific to seismic design only the note that mandates a
penalizing factor that is applied for structural panels with H/W between 2 and
3.5. Also, there is a program setting that allows you to disallow the segments
between 2 and 3.5 to avoid the factor.
For
these reasons it is in fact more important that the setting be applied to wind
than to seismic - wind design does not have the penalty so it would be more
advantageous to ignore gypsum to get the full design strength from segments
between 2 and 3.5
Furthermore,
you may want to set the wind and seismic settings separately because of the
differences in seismic and wind design in this regard.
b) New Design Setting
To solve
this problem, a design setting has been added to allow you to ignore non-wood-panels
when combined with wood for wind design. Refer to the Input section below for
more details on this setting and related changes to the settings that allow you
to ignore non-wood-panels in various circumstances.
3. Wind
Design In the Presence of Seismic Loads (Bug 1636)
Wind
design results could differ if design was performed in the presence of seismic
loads vs. their absence, under the following conditions
setting
Allow 3.5:1 height-to-width ratios for seismic design is not set
(unchecked)
and
there are shearwall segments with height-to-width (H/W) ratios between 2
and 3.5 ( between app. 2’3-3/8” and 4’-0” for 8-foot high walls)
the
walls with those segments are sheathed with structural wood panels
there
are not also sheathed with other materials, or the “Ignore non-wood when
combined with wood” design setting is set
In
this case the program used the provision from SDPWS Table 4.3.4 and IBC Table
2306.3.4 restricting shearwall H/W ratio to 2:1 rather than 3.5:1 for seismic
design, except that it mistakenly applied it to both seismic and wind. It
therefore discounts some segments for wind design based on seismic H/W
limitations when they should be included.
The
program now uses separate H/W ratios for wind and seismic design. The consequences
of this change are described in the following sections.
a) Wind Shear Force Calculations with Seismic H/W
Ratios
When
the program used seismic height-to-width ratios for wind design, the affected
shearwalls would have less full-height-sheathing (FHS) than they should,
resulting in a higher shear force per unit length. This created a conservative
overloading of the shearwall.
For
lines with segmented walls with forces distributed according to shearwall
capacity the percentage overloading is by the total FHS divided by the FHS
minus the neglected FHS. For lines with perforated walls or with forces
distributed by assigned rigidity, the situation is more complicated.
b) Perforated Shearwall Factor for Wind Design
with Seismic H/W Ratios
When the
program used seismic height-to-width ratios for wind design, affected
perforated shearwalls would have a lower percentage of full height sheathing
than they should, resulting in a lower perforation factor Co ( SDPWS
Table 4.3.3.4 and IBC Table 2305.3.8.2). This results in a lower shear capacity
for the entire shearwall, and possibly conservative design.
c) Wind Hold-down Forces with Seismic H/W Ratios
When the
program used seismic height-to-width ratios for wind design, the program would
fail to place hold down forces on those segments it mistakenly designated as
non-FHS. The other hold-downs on the line would report a conservative hold-down
force by the ratio of the neglected FHS to the total FHS on the line.
d) Wind Drag Strut Forces with Seismic H/W Ratios
When the
program used seismic height-to-width ratios for wind design, it would fail to
place drag strut forces on those segments it mistakenly designated as non-FHS.
The other drag strut locations would report a conservative (high) drag strut
force. The extent of the error depends on the positioning of the drag struts on
the line, but can be very significant.
e) Wind Design of Walls Composed Entirely of
Seismic Non-FHS Segments
When
the program used seismic height-to-width ratios for wind design, in cases where
the segments with H/W rations between 2 and 3.5 are the only segments on the
wall, the program did not design these walls or report the results for these
walls in the design results report.
It
is possible that these neglected walls could be critical for design if they
were perforated walls, or if the Design shear force based on wall rigidity
setting is set and these segments are assigned a high rigidity. The latter is
an unlikely scenario as narrow shear wall segments are less rigid than wide
ones.
f) Shearline Determination for Wind Using Seismic
Height-to-width Ratios
When the
program used seismic height-to-width ratios for wind design, in cases where the
segments with H/W rations between 2 and 3.5 are the only segments on the entire
shearline the program would determine that there were no shear resisting
segments on the line, when in fact for wind design there should have been. The
consequences of removing a shearline in this fashion are described in the Load Distribution section, below.
4. Sorting
of Openings (Bug 2099)
Although the program sorts the openings input in
Opening view from left to right on the wall, occasionally the sequence of
openings becomes unsorted in the course of program operation. Attempts have been made to capture this
problem and resort them to avoid problems that were occurring in the following
program areas.
a) Full-height sheathing Determination
We have
now ensured openings are sorted in determining the length of full-height
sheathing segments, and all the effects this has on force distribution and
shearwall design.
b) Hold-down force Determination
We have
now ensured openings are sorted in determining the segment length to be used in
hold-down force calculations.
c) Drag strut Force Determination
We have
now ensured openings are sorted in determining the length of shearwall segments
to be used in drag strut force calculations.
d) Shearline Force Determination
We have
reduced the possibility that unsorted openings are affecting shearline force
calculations, but it is possible that unsorted openings could still be having
an effect in this area. If you see suspicious shear results, check for unsorted
openings; it may be necessary to re-enter the openings.
e) Shear Ration Rmax
For UBC
design only, for the calculation of Rmax used in redundancy factor
calculations. The problem has been corrected.
G. Load
Generation and Distribution
1. Force Distribution on Walls with no Shearwall
Capacity (Bug 2034)
With the
addition the Ignore non-wood-panel
contribution to seismic design for All
walls setting ( see Engineering Design, and Input), it
is now possible to have entire shearwalls and entire shearlines with a
sheathing capacity of zero. In these cases, these shearwalls are treated as
non-shearwalls or non-shearlines, with the following consequences
a) Shearwall With No Capacity
No force
is applied to walls with no shearwall capacity for this reason, and the
shearwalls are not designed. The wall is treated as an opening, gap, or
non-shearwall is for hold-down and drag strut creation.
b) Shearline With No Shearwall Capacity
No
shearline force is assigned to that line, and no shearwalls on that line are
loaded. No drag strut forces, hold-down forces or designed shearwalls are
created for the line.
c) Flexible Diaphragm Distribution
The
program assigns the load on that would have gone to that line to the two
adjacent lines, according to the distance from those lines to the non-loaded
line.
d) Rigid Diaphragm Distribution
The
program does not include the line in torsional rigidity calculations, which
will cause the force that would go into that line to go into other lines in a
way that depends on the position of those lines and their rigidities.
e) Vertical Discontinuities
If there
are walls with shearwall capacity above the level on the line that is no longer
loaded, the program distributes the load from the upper level to adjacent
shearlines on the lower level. The load
path continues down the adjacent shearlines, so that the shearwalls on the
level below the non-loaded level do not receive the load from the same line two
levels up.
2. Shearline Determination for Wind Using Seismic
Height-to-width Ratios (Bug 1636)
When the
program used seismic height-to-width ratios for wind design (described in the Engineering Design section above) , in cases where the segments with H/W rations between 2
and 3.5 are the only segments on the entire shearline, the program would
determine that there were no shear resisting segments on the line, when in fact
for wind design there should have been. The consequences of removing a
shearline in this fashion are:
a) Shearwall Design on Neglected Line
No
shearline force was assigned to that line, and no shearwalls on that line were
loaded. The program now loads lines for wind design that are not loaded for
seismic design.
b) Flexible Diaphragm Distribution
The
program assigns the load on that should go to that line to the two adjacent
lines, according to the distance from those lines to the neglected line. This
creates conservative design on the adjacent lines.
The
program now determines the shearlines to be loaded using flexible distribution
separately for wind and seismic design.
c) Rigid Diaphragm Distribution
The
program would not include the line in torsional rigidity calculations, which
will cause the force that would go into that line to go into other lines in a
way that depends on the position of those lines and the rigidity. It would
cause conservative loading in some or all of the other lines.
It
is also possible that the program would incorrectly decide that there were not
sufficient shearlines to perform rigid design, based on seismic h-w rations,
for wind.
The
program now determines the shearlines to be included in rigid distribution
separately for wind and seismic design.
d) Vertical Discontinuities
If there
are walls with FHS segments above the level on the line that is
neglected, the program will distribute the load from the upper level to
adjacent shearlines on the lower level, resulting in conservative loading on
those lines. However, if there are FHS on all shearlines on the level below the
line that is neglected, the load path will continue down the adjacent
shearlines, so that the shearwalls on the level below the neglected level will
not receive the load that it should receive from the neglected level. This can
result in non-conservative design on the lower level walls.
3. Rigid
Diaphragm Wind Load Distribution for
Overhangs in the Presence of Seismic Loads (Bug 2059)
Slightly different shearline forces were generated
if wind load rigid diaphragm distribution is done when generated seismic loads
were present than in their absence, for the parallel-to-ridge direction of
loading.
This is because the building width (i.e. the extent
of the loads) was calculated using all generated loads on the structure, and
seismic loads are generated on the gable end roof overhang. Wind loads are not
generated on these surfaces because the overhanging side roof panel is
orthogonal to the wind direction, and the program does not model cornice boxes
in the direction of loading.
The larger width creates a greater eccentricity and
higher torsional moment, therefore larger torsional component of loads. This
problem was therefore conservative. It has been corrected by calculating the
building extent for wind and seismic forces separately, using wind and seismic
loads, respectively.
4. Seismic
Loads Generated from North-South
Roof Overhangs (Bug 2095)
If the overhangs on the north and south sides of
building are not the same, the seismic loads in the east-west direction that
should have been be generated on the north overhang were generated on the
south, and vice-versa. This has been
corrected.
North-south loads on east and west overhangs were
not affected.
5. Differing
Drag Strut Forces in Opposing Directions (Bug 2016)
The drag strut
forces reported in the Drag Strut and
Hold-down table were randomly taken from either the east-west or west-east
force direction ( similarly for N->S and S->N), so that when forces from
these directions differ, only half the force values are reported. The reported
forces could be a confusing mixture of forces from each direction that did not
correspond to any elevation view diagram. Note that it is rare for forces to
differ in opposing directions, however they can for unbalanced loading as in
the case of a monoslope roof.
This problem has
been corrected by outputting the drag strut value for both force directions for
each drag strut location in the Drag Strut and Hold-down table.
H. Input and
Program Operation
a) Design
Codes in About Box (Change 41)
The program now gives the most recent design codes
implemented in the Help About box,
under the version number.
b) Welcome
Dialog Via Help Menu (Change 44)
The Welcome box can now be accessed from the Help
menu, so that you do not have to restart the program to access the information
in this box.
a) Unknown
Gypsum Nail Spacing on Interior Surface (Change 42)
Starting
with version 8.1, if Gypsum Wallboard
is the sheathing material selected for both wall surfaces independently, the
program mistakenly allows Unknown as
a choice for the nail spacing on the Interior
surface (or Side 2 for interior walls).
If
Unknown is selected, the program
output shows a “?” for the nail spacing in the Materials table, but designs the
shearwall using the largest gypsum wallboard capacity possible (175 plf).
Unknown is not the default value, so this problem would occur only if you had
selected it.
For
version 8.2, Unknown is once again
allowed as an option only on the exterior surface, or on both surfaces when
they designated as having the same materials, as the program cannot design two
different sheathing surfaces independently.
b) Multiple Selection of Fibreboard Materials (Bug
1993)
After
selecting more than one wall, and selecting Fibreboard on the interior wall
surface in the wall input dialog, the fastener type appeared as a blank. If
left blank, the selected fibreboard materials were not included in the design
capacity of the wall. However, selecting a fastener type allowed for design.
This
problem has been corrected.
c) "Both Sides Same" for Multiple
Selection of Walls* (Bug 1994)
In the
wall input dialog, after more than one wall is selected, and then Both sides the same" is selected,
the individual walls are often not designated as both sides the same when
re-selected. Some of the fields have the original value in them, that is, were
not properly updated for all of the walls selected. This has been corrected.
a) Partial Wall Load Input (Bug 1911)
When
adding a line load in the load Input dialog when “Selected Wall” was set as the
“Apply to..” selection, then changing
the locations such that they are less than the full extent of the wall, the
load was still being added to the full length of the selected wall. This has
been corrected such that the load is given the reduced extent that was entered.
a) Ignore
Non-wood Panel Contribution Box (Bugs 2034 and 2035)
The setting that appeared in the Seismic Design data group Ignore non-wood sheathing when combined with
wood has been expanded to three separate settings in a new data group
called Ignore non-wood-panel
contribution... The new settings are described below.
b) Seismic Ignore non-wood-panel Setting for All
Walls (2034)
A setting has been added to ignore non-wood-panels
in design of all walls. The materials whose strength contribution is neglected
when this is checked are fiberboard, gypsum wall board and other gypsum and
plaster materials, and lumber sheathing.
Refer to the
corresponding item in Engineering Design for the
rationale behind this change.
The
existing setting that ignored the seismic contribution of these materials only
when combined with structural wood panels remains in the program, and is
disabled and checked if seismic design is ignored for all walls.
The
default value for this setting is to be unchecked. Files from previous versions
will have this value unchecked.
It
is saved to the project file and can be saved as a default for new files.
c) Ignore Non-wood-panel Setting for Wind Design (Bug
2035)
Previously,
the Ignore
non-wood when combined with wood setting applied to seismic only, now there
are separate settings for seismic and wind design. Refer to the corresponding item in Engineering Design for the rationale behind this change.
Like
the corresponding seismic setting, the default for this setting is unchecked.
However, it will be checked for project files from version 8.1 and before if
the corresponding seismic checkbox is checked.
It
is saved with the project file and can be saved as a default for new files.
It
is disabled and unchecked when the Disregard
shearwalls height to width ratio setting is checked, as there is in that
case no good reason to ignore the wood panels for design.
d) Interaction
of Allow 3.5:1 Height-to-width Ratio and Ignore Non-wood Settings (Bug 2038)
When
the Allow 3.5:1 height-to-width ratios
(seismic) checkbox is unchecked, then the Ignore
non-wood panel … when combined with wood panels for
seismic design is disabled and unchecked. The advantage to ignoring non-wood
panels only exists if you area allowing height-to-width ratios between 2
(gypsum and other non-wood) and 3.5 (structural wood panels), with a penalty
for structural wood panels given in SDPWS Table 4.3.4 and IBC Table 2306.3.4.
Note
that the reason one might not allow 3.5:1 H/W ratios is that it is often
advantageous to neglect the short segment rather than have the penalized
resistance govern on a wall with other full-height segments.
Previously these controls were not related.
Exception:
If the new Seismic – for all walls
checkbox is checked, then the Seismic –
when combined with structural wood panels remains checked. In this case, the contribution is ignored for
reasons relating to R value, not height-to-width ratio.
e) Interaction of Disregard H/W Ratio and Ignore
Non-wood Contribution Settings (Change 54)
When
the Disregard shearwall height-to-width
limitation is checked, the Ignore non-wood panel contribution…when
combined with wood panels settings
now disabled as well as being unchecked, as before, becausethere is in that
case no good reason to ignore the wood panels for design.
Exception:
If the new Seismic – for all walls
checkbox is checked, then the Seismic –
when combined with structural wood panels remains checked. In this case, the contribution is ignored for
reasons relating to R value, not height-to-width ratio.
f) Nomenclature
for Non-wood Panels (Bug 2036)
We have changed the nomenclature “non-wood
sheathing” to “non-wood-panel” in recognition that the materials that are to be
ignored when this is checked include lumber sheathing.
We have changed the phrase “when combined with
wood” to “when combined with structural wood panels” for the same reason, and
to emphasise the terminology used in the design codes.
a) Random
Design Crash ( Change 50)
A random and very infrequent crash on shearwall
design was removed.
a) Ignore Non-wood-panel Setting (Bug 2034, 2035)
The new settings added for ignoring the shear
contribution of non-wood-panels for wind design and for all walls designed for
seismic have been combined with the existing seismic setting (when combined
with wood) in a new section of the Design
Settings table. There are now columns for wind design and seismic design,
with the choices Always; When comb'd w/ wood panels; Never.
Previously this setting was called Seismic
Materials with choices Ignore or Include non-wood contribution.
The new settings are described in more detail in Input
( 2034 and 2035) and Engineering
Design (2034 and 2035).
b) Force
Distribution within Shearline Setting (Change 52)
The checkbox in the Design Settings that allows you to specify that the force
distribution to individual shearwalls is based on shearwall rigidity is now
recorded in the output report. This setting was added in Version 7 of the
software, but not echoed in the output.
It is recorded in the Design Settings table, under
Design shearwall force/length.
c) Drag
Strut Force Calculation Method ( Change 53)
The ability to indicate whether drag strut forces
are based on shearwall capacity or applied load is now recorded in the output
report. This setting was added in Version 8.1 of the software, but not echoed
in the output.
In the Design
Settings table, the field that previously said Hold-down Forces now says Collector
forces based on… and has separate lines for drag struts and hold-downs.
d) Reporting
of Moisture Content Setting (Bug 2032)
The In-service and Fabrication moisture content
values were always reported as > 19% in the Design Settings portion of the output report, even when < 19% is
selected as the moisture content in the Design
Settings. This was a reporting issue and did not affect the service
condition factor used for nail withdrawal design, as shown in the Components and Cladding table
e) Maximum-Height
to Width Material Nomenclature ( Bug 2036)
The material designation in the maximum
height-to-width section in the Design
Settings table for “Plywood” has been changed to “Wood Panels”, in
recognition of the fact that these structural panels can be made from oriented
strand board (OSB) materials, not just plywood.
2. Drag
Strut and Hold-down Forces Table
a) Direction
of Drag strut Forces (Change 46)
The single column for drag strut forces at program
locations has been expanded to two columns headed by arrows pointing in
opposite directions. These represent forces in opposing directions, e.g.
east-west and west-east.
In most cases these forces are the same, but they
can differ, as in the case of a monoslope roof creating differential wind loads
in opposing directions.
b) Load Case
(Change 46)
The column “Ld. Case” has been expanded to read
“Load Case” .
J. Installation
and Documentation
a) Keycode
System
Woodworks returned the more secure keycode system
that requires you to contact WoodWorks Technical Support for a keycode to the
software, rather than using the keycode supplied with the software.
b) Version
History in Installation (Change 51)
It is now possible to access this document directly
from an icon on the start menu rather than indirectly through the Readme files.
Shearwalls
8.11 – March 11, 2009
c) This version was issued to fix the following
problem introduced in version 8.1:
Repetition
of Company and Project Information
The
Company Information and/or Project Description as input in the Settings are
repeated in the Company and Project Information tables of Design report for
each design run in a particular session. This can be avoided by deleting the
information in the settings after the first design run.
Shearwalls 8.1 – February 27, 2009
This version of Shearwalls was issued to provide
the following corrections and enhancements to Shearwalls 8.0. It was released as a Stand-alone Shearwalls and
as part of Design Office 8, Service Release 1.
1. Rigid Diaphragm Distribution
a) Rigid Diaphragm Shearline Forces for Negative
Locations (Bug 1802)
The
forces distributed to shearlines by the Rigid Diaphragm method in a particular
direction were too large, typically by 5% to 10%, for buildings which extend in
the other direction into the negative quadrant.
b) Warning for Rigid Non-Design (Bug 1759)
When the
program does not have sufficient loaded shearlines using the flexible
distribution (I.e. two per direction), so that the program cannot perform rigid
distribution, a message now warns the user of this situation.
c) Rigid Diaphragm Results in Log File (Bug 1803)
Refer to
the Output
section of this list for extensive changes made to the detailed log file output
for Rigid Diaphragm distribution.
a) Drag Strut Force using Shearwall Capacity
(Change 31)
The
design settings have been changed to enable you to select shearwall capacity
(rather than applied loads) for calculating the drag strut forces, as was
previously possible only for hold-downs.
The drag
strut force using applied shear is calculated by taking the absolute value of
the difference between the design shear in each segment and the shear flow on
the diaphragm at the top of the shearwall. Using shearwall capacity, this value
is simply multiplied by the ratio of shearwall capacity of the design shear
wall total design shear force. Note that this means that the correction for
perforation factor Co for the critical wall is applied to the entire shearline.
Note too that if shear force is distributed to the segments via shearwall
rigidity (design setting) the critical segment ratio is also applied to the
entire line.
If some
shearlines do require shearwall capacity design, and some do not, it will be
necessary to run the design twice, with different Drag Strut Force settings.
b) Vertical Loads on Non-shearwalls and
Non-full-height-sheathing Segments (Bug 1682)
User-input
dead and uplift loads are now distributed to non-shearwalls and non-full height
segments within shearwalls, and then transferred to the floors below via the
same hold-down force mechanism as for shearwalls. Previously no loads were created for these
portions of the walls, and these loads were not properly tracked down the
structure.
Separate
vertical loads are created on openings in perforated walls that are not
enclosed by full height sheathing segments, and also the non-FHS segments at
wall ends. Previously, no loads were created for these portions of perforated
walls. A portion of a perforated wall enclosed by FHS segments has one vertical
load extending across that portion, as before.
c) Drag Struts for non-FHS Segments. (Bug 1683)
Drag
strut force calculations were incorrectly adding a force due to non full height
sheathing (non-FHS) segments to the force from an adjacent FHS when the non-FHS
segment was at the end of a wall, creating higher drag strut forces than the
correct ones, and creating an additional drag strut force location.
d) Hold-down offset note (Change 38)
A note
referring to AWC Special Design Provisions for Wind and Seismic (SDPWS) eqn
4.3-4, from 4.3.6.1.1, indicates that the moment arm used for hold-down force
calculations does not account for this offset. The equation 4.3-4 is T = C =
vh, where v = VL, L being the entire length of the shearwall segment without
subtracting the offset.
e) Default Hold-down offset (Change 39)
The
default hold-down offset has been reduced from 3” to 1.5”, in recognition that
the chord force is actually transferred to the hold-down connection at the
centre of the chord, not where the holddown bolt goes through the floor joist.
a) Period T in Determination of Sds
using ASCE 7 12.8.1.3
(Change 10)
The
condition that period T must be less than 0.5s to use ASCE 7-05 12.8.1.3 to
limit the ground acceleration Ss value to 1.5 when calculating the spectral
response coefficient Sds was not being
implemented. The program now checks the
value of T input in both directions, and
calculates separate Sds values for each direction if only one is greater than
0.5.
b) ASCE 7 Load Generation in Log File Output (Bug
1849)
Refer to
the Output
section of this list for extensive changes made to the detailed log file output
for ASCE 7 Load generation, in particular the treatment of Ss and Sds for ASCE 7 12.8.1.3
c) Seismic Response Modification Factor (Bug 1904)
The
message upon seismic load generation that allows you to change the ASCE 7
seismic response modification factor R to the one appropriate for the materials
being used has been improved in the following ways:
-
In
Presence of Non-Wood
Currently,
when gypsum or fibreboard materials are present, the program allows you to
override the warning message and use an R value greater than 2.5, the largest
in ASCE 7 Table 12-2-1 for the building systems considered.
Now the
program gives you a choice of automatically selecting the Ignore non-wood design setting, or changing the R value to one less
than or equal to 2.5.
-
No
Non-wood Present
The
program now warns you if you have unnecessarily entered a value of 2.5 or less,
corresponding to gypsum and fibreboard materials, when there are no such
materials in a particular direction. It allows you to change the value to 6.5,
the value for bearing wall systems in Table 12-2-1
-
Ignore
Non-wood Materials
The
program now warns you if you have unnecessarily set the Ignore non-wood design setting with an R value of 2.5 or less for a
particular direction. It offers you the choice of automatically deselecting the
setting, or increasing the R value to to 6.5, the value for bearing wall
systems in Table 12-2-1.
-
Analysis
in Both Directions
The
above messages and actions are taken independently for each force directions,
to comply with ASCE 7 12.2.2. The
program had been making the changes to both directions, even if they applied to
only one, to comply with the ASCE 7 2002 code (9.5.2.2.1) for R less than 5.
d) Persistence of ASCE Seismic Design Category (Bug 1894)
The
program sometimes used a Seismic Design Category (SDC) of “A” even if this is
the not the correct category according to ASCE 11.6. This happened if an
existing project is opened and a design was run without repeating the load
generation. The incorrect category
appeared in the Site Information design results table, along with any warnings
or notes in the design results that depend on SDC. It is also used in any load
distribution or design calculations that depend on SDC, for example redundancy
calculations.
e) Building Mass on Flat Roof Overhangs (Bug 1890)
Shearwalls
does not create building masses or for those portions of flat roofs that are
part of the overhang, resulting in lower seismic loading for those roofs due to
the absent building mass and snow load. This problem has been corrected by not
allowing structures with flat roofs to have overhangs.
To
correct existing projects with flat roofs you need to enter the Roof Input
dialog and deselect and reselect the Flat roof. Doing this sets the overhangs
to zero.
f) Wind Load Generation on Multiply-Joined Roof
Blocks (Bug 1758)
When
three blocks were aligned in one direction, and when the “Exclude roof portion
cover by other roof" option was checked, for the ASCE-7 medium rise
method, loads were not displayed on the screen nor did they contribute to
design loads on the structure.
a) Manually Applied Wind Shear Loads (Bug 1809)
Manually
applied ASCE all-heights wind loads entered on the west and south faces, when
seismic load but no wind loads had been generated, did not show up on the
screen nor are included in the design results, despite the fact they were in
the load list.
a) Gypsum on Exterior Wall (Feature 89)
It is
now possible to have gypsum wallboard on the exterior of the of a perimeter
wall. The program does not perform C&C wind design in this case, and issues
a warning to that effect in the Design
Results output.
b) No Materials on Exterior Wall (Feature 49)
It is
now possible to specify None as the
material on the exterior of the of a perimeter wall. The program does not perform
C&C wind design in this case, and issues a warning to that effect in the
Design Results output
c) Primary Design Surface (Features 49, 89)
Previously,
the exterior surface of a perimeter wall, and the side designated as Side 1 of
an interior partition, was designated as the primary design surface in the case
that materials were different on either side. You were able to designate some
parameters for that surface as unknown, and the program would design for these
values.
Now, the
side of the wall that has structural (plywood, fibreboard, OSB) materials is
designated as the primary side, and the side with gypsum or no materials is the
non-designed side. If both sides have structural materials, then the primary
side is the exterior of perimeter walls and Side 1 of interior walls, as
before.
d) Duplication of Wall Group (Bug 1810)
Occasionally
extra wall groups were created for walls on the upper level of multi-storey
structures that are identical in material composition as walls on the lower
levels, when it should be including them all in the same group.
a) Zero Shear Capacity for Structures with Narrow
Walls (Bug 1652)
Saving a
project prior to designing a structure with narrow wall segments caused the
seismic allowable shear capacity to be calculated as zero, and displayed as
such in both Elevation View and the Design Results. Note that the project
could be reopened and a valid design run performed. A valid design is now performed in all
circumstances.
3. Component
and Cladding (C&C) Wind Design
a) Fastener Withdrawal Force for Unknown Stud
Spacing (Bug 1895)
If the Stud Spacing was set to unknown, then the fastener withdrawal
force was calculated as zero. This resulted in all the fastener withdrawal load
and capacity values not being output in the Components and Cladding table.
b) Design for Exterior Shearwalls with No C&C
Resistance (Change 36)
As it is
now possible for there to be no materials, or non-structural (gypsum) materials
on the exterior walls, for such a shearline, a double asterisk (**) is output as the response ratio in the C&C
results table, indicating the following beneath the table: **WARNING - No exterior sheathing material or sheathing has no C&C
capacity.
a) Metafile and Project File in Separate or
Renamed Folders (Bug 1740)
If a CAD
metafile is not in the same folder as when it was first imported, the program
prompted you to browse for the location of the CAD metafile to display, but
Shearwalls was unable to retrieve and display the selected file. This has been
rectified, so you now have the ability to send complete project specifications,
including the CAD file, to other WoodWorks users.
a) Ceiling Depth Change upon Return to Structure View
(Bug 1728)
Changing
the ceiling depth of the top floor in the Structure
input form after walls have already been created is no longer incrementing the
wall heights of existing walls on the top floor by the ceiling depth.
b) Wall Height Check upon Return to Structure View
(Bug 1787)
The
program did not perform the check on allowable wall height input in Structure input form, if you had
returned to that form from a later view in the sequence. Therefore, it was
possible to accidentally enter a zero height wall, which would cause the
program to crash. Now the program checks that a legitimate wall height is input
whenever the Structure view is
exited.
a) Wall Surface Input Mechanism (Change 32)
The drop
list for selecting Wall Surface in the Wall Input view has been replaced by two
tabs called Interior side and Exterior side ( Side 1 and Side 2 for interior
partitions). These tabs contain all the input fields that previously were
visible when Exterior and Interior were chosen from the drop list.
b) Both Sides the Same (Change 32)
The
choice Both sides same has been
replaced by a checkbox that causes the input to be compressed into one tab
called Both sides. As before, the
materials that are displayed are the ones that were on the exterior side (or
Side 1) before the box is checked.
c) Wall Surface Input Mechanism (Change 32,
Feature 49)
The
choice Exterior only has been
removed, as it can be achieved by specifying None for the interior side of the wall.
d) Gypsum on Exterior Surfaces (Feature 89)
The sheathing
materials None, Gypsum Wallboard, and Gypsum Sheathing are now available on
the exterior surfaces of exterior walls, and to either side of interior walls.
Note that Wire Lath and Plaster and Gypsum
Lath, are still not available on the exterior.
e) No Materials on Exterior Surfaces (Feature 49)
The
choice None has been added for the
exterior side, to allow for no structural materials on the outside of a
structure with structural materials on the inside surface.
The
program does not include the selection None
if None is selected on the other
side of the wall, in other words, shearwalls must have sheathing on at least
one side.
f) Side with Unknowns (Features 49,89)
Previously,
the exterior side of perimeter walls and Side 1 of interior partitions could
have unknown parameters for sheathing thickness, nail size, and nail spacing.
Now, the
side of the wall that has structural (plywood, fibreboard, OSB) materials can
have unknowns, and the side with gypsum or no materials does not have them. If
both sides have structural materials, then the program reverts to its previous
behaviour.
g) Relative Rigidity Label (Change 20)
The
label Relative rigidity has been changed to Relative rigidity per unit length.
a) Crash on Standard Wall Cancel (Bug 1889)
When
editing a Standard Wall, then pressing Cancel, Shearwalls
would crash. This happened only for existing projects that are reopened, not
for new files. This has been fixed.
b) Relative Rigidity for Standard Walls (Change 4)
Added
relative rigidity field to standard wall definition so that you can create
multiple walls with same rigidity. Only active if the setting Manual input of shearwall rigidity is
checked. It defaults to 1.0 for new standard walls
c) Reversed Default Standard Wall Definitions (Bug
1729)
The
default standard walls that come with the program for non-shearwalls and
perforated walls on the interior of the structure are no longer reversed.
d) Standard Wall Dropdown Box Length (Change 14)
The
dropdown box for Standard walls has been lengthened, so that you do not think
that only one standard wall can be created because that is all that is shown
without scrolling.
e) Selection of Standard Walls for C&C Design
(Change 37)
As it is
now possible to have non-structural materials on exterior surfaces, and because
all walls should be available for seismic design, the program no longer issues
a message and prevents you from selecting a standard wall for the exterior of
the building that cannot withstand wind C&C loads.
a) Period Input Order (Bug 1818)
In the
ASCE 7 and IBC, the short period (Ss) maps are listed before the one second
period (S1) maps, but the input order was reversed in the Building Site window.
a) Nail Withdrawal Moisture Conditions (Change 22)
In the "Nail withdrawal conditions" data
group, the choices for Fabrication and
In-service moisture conditions have been changed from "Wet",
"Dry" to ">19%", "<= 19% to correspond with the
terminology in NDS Table 10.3.3.
b) Hold-down Force Setting Persistence (Change 24)
The Design setting Holddown forces based on Shearwall capacity was not saved when the
project file was saved, so it would be reset to the default value, Holddown forces based on Applied loads
when projects were re-opened.
c) Design Settings in Data Bar (Change 30)
The
"Design…" button on the Data bar has been renamed to
"Settings…", to avoid confusion with the Design button in the toolbar
which causes a design to be run.
a) Immediate Effect of Default Settings (Bug 1693,
Changes 25, 26)
In the
Default Settings page:
-
The
asterisks and explanation at the bottom of the form for the immediate effect of
some settings have been restored. They were dropped for version 2004b.
-
The explanation has been revised to indicate
that only Roof geometry settings
depend on exiting Structure View.
-
An asterisk has been added the Holddown offset to indicate that it has
immediate effect.
b) Occupancy Dropdown Width (Change 27)
In the
Settings Default Values property page, the Occupancy dropdown box has been made
wider to accommodate the longer selections.
c) Proportion of Snow Load Spelling (Change 19)
In the Self-weights data group there was a
spelling mistake: “Proprotion of snow used"
a) Load Case Labels (Change 28)
In the
Loads and Forces settings, the label North-south
wind direction (low rise) has been changed to Case 1 (all heights); and
East-south wind direction (low rise) has been changed to Case 2 (all heights). This corresponds
to changes made in the functionality of these checkboxes in version 2004c.
a) Legends and Notes (Change 9)
-
The
Design Results have been updated so that the notes under the tables are in
plain face to distinguish them from the legends, which are in italic.
-
Those
notes that are considered warnings that indicate design failure are now output
in red and are the last notes printed.
-
A
heading of 'Legend:' now precedes the legends and the program now consistently
places the heading "Notes" before notes.
b) Unreadable Design Results with Certain Printers
(Bug 1790)
For
certain printers the design results reports shown both on the screen and as
printed are very narrow with a large right margin. All information was
unreadable. This has been fixed.
c) Log Filename Persistence (Bug 1851)
The
filename of the log file was not updated when you changed the project file
name. Therefore, when a design was run when the project is still called
“Untitled.log” it maintained that name, even after the project file was given a
more meaningful name. The log file name is now updated to correspond to the
project file's current filename.
d) Text-based (.wsr) Output Files (Bug 1886)
The
program no longer outputs Shearwalls text-based results files (.wsr), as they
have not been maintained since the enhanced output was introduced for
Shearwalls 2004 USA.
The
extension .wsr has been removed from the filename on the header of the printed
file output, which in fact can be output as .rtf or .pdf.
a) Seismic Materials (Change 33)
In the
Seismic Materials box of the Design Settings, we now refer to “non-wood”
instead of “gypsum”, as the setting causes fibreboard to be ignored as well as
gypsum.
b) Building Regularity (Change 12)
A table
entry has been added to the Site
Information table of the Design
Results indicating the Structure Type
- Regular or Irregular, as input in the Site
Dialog.
c) ASCE 7 Site Coefficients Fa and Fv
(Change 13)
Table
entries have been added to the Site Information table of the Design Results,
giving the values of ASCE 7 seismic site coefficients Fa and Fv.
These values are input by the user of the program for Site Class F, and
sometimes for class E, otherwise they are calculated by the program.
d) Nail Withdrawal Moisture Conditions (Change 22)
In the
Site Information table, fabrication and in-service moisture conditions are now
output as ">19%" and
"<= 19% to correspond with the terminology in NDS Table 10.3.3.
a) Perforation
Factor Co in Base Shear Vmax in Design Results (Bug 1860)
According
to the legend below the Shear Results
table, the value Vmax in the Design Results output for perforated
walls is supposed to show the base shear flow divided by the Co
perforation factor, however, it showed the base shear flow without dividing by
Co. It now shows the value divided by Co.
b) ASCE-7 Low-rise Low-slope Note (Bug 1808)
The note
indicating that no wind pressures are generated on roof panels with slope less than 22.5
degrees, due to Shearwalls implementation of ASCE 7 low-rise Figure 6-10 Note 6, has been placed in the introductory portion of the Shear
Design Results to make it more apparent.
The note that was under the Wind Load table has also been retained.
c) Components and Cladding Table Legend ( Changes
3, 17)
There
was an unfinished sentence in the C&C Table Legend. It has been corrected
as "C&C end zone exterior pressures using negative (suction)
coefficient in ASCE 7 Figure 6-11A added to interior pressure using
coefficients from Figure 6-5".
a) Shearline Force Arrow Location in Elevation
View (Bug 1900)
In
Elevation view, the Shearline force arrow has been moved from the top of the
floor or roof framing above a wall to the top of the wall in order to clearly
show that the moment arm in the overturning calculations is the wall height and
excludes the depth of the floor or roof framing.
b) Vertical Loads in Elevation View Legend (Change
1)
Lines
were added in the Elevation View legend to show symbols for wind uplift and
dead loads, also indicating that these loads are unfactored
c) Truncated Elevation View Material Information
and Legend (Change 6)
The
printed version of the Shearwalls output form cut off the legend and wall
material information at the length of the wall, when there was room on the page
to print it all. This has been fixed
d) Failed Design for Perforated Walls with No
Full-height Segments (Bug 1848)*
e) When a perforated wall within a line has no full-height-sheathing segments, the
program indicated "Failed" in elevation view on the shearline, and
reported nonsensical values as the design response for the shearwall in the
Shear Results table.
5. ASCE 7 Seismic Load Generation in Log File
The
following changes apply to the ASCE 7 Seismic Load Generation section of the
log file
a) SS for SDS Using ASCE 7 12.8.1.3 (Bug 1849)
In the
Log file, the program was displaying the value of the spectral acceleration
parameter SDS using only the
mapped value of SS in equations 11.4-1 and 11.4-3. Now it also shows the value using
SS = 1.5 according to ASCE
12.8.1.3. (The SS = 1.5
value is used for all regular structures five stories or less with a period of
0.5s or less in the calculation of SDS for the seismic response
coefficient CS. )
Since
the program now calculates SDS separately for each force direction (
see U.3.a) above ) the SDS used for determination of CS
according to 12.8-2 is now shown in the lower table for each force direction,
along with the SS value used. The value of SDS that uses
the user-input SS instead of SS = 1.5 is still shown, in
the upper table, because it is used for the determination of the seismic design
category, according to Table 11.6-1. The user-input SS is also shown
where other user-input values are.
Finally,
-
a
note at the bottom of the section explains the differences between the SDS
and SS values shown for seismic design category and CS
calculations,
-
in
the In the User Input and Source section, an asterisk (*) has been place
beside the word "mapped", indicating an explanatory line that gives
the conditions for Ss = 1.5 to be applied according to 12.8.1.3.
Note
that this was only a display error - the correct value of SDS was
used to calculate the seismic response coefficient CS using 12.8-2, so that the
equation CS = SDS * I / R shown in the log file did not
always correspond to the SDS shown. However, CS and the
resulting base shear V were not affected.
b) R and T Explanations (Change 11)
A line
has been added to the user input explanations indicating that the values of
response modification factor R and period T are shown in the base shear
calculation table. These values can be input or calculated.
c) Regular or Irregular Building Input (Change 12)
A line
has been added to the explanation of user inputs, indicating giving ASCE 7
reference for irregularities, with the user selection of building regularity (Regular or Irregular) indicated below.
d) Use Groups Removed (Change 11)
The
table column 'Use' , for ASCE 7 -02 use groups, has been removed, as ASCE 7 05
does not have use groups.
e) Formatting Changes and Typos (Change 11)
-
A blank line has been added before the title User Input and Source:
-
The
importance factor I is given with 2 decimal places instead of 3.
-
The
extra ampersand (&) was removed from "AF&PA"
-
"Sd" was changed to "Ss"
in the definition of Fa
6. Rigid Diaphragm Analysis in Log File (Bug 1803)
The Rigid
Diaphragm Analysis section of Log File has been modified in the following ways:
a) Explanatory Line for Rigidity Selection
A line
has been added at the top of the section that indicates the Shearwall Rigidity
selection in the Design Settings, and to explain what rigidity units are
employed with each selection. For “Shearwall capacity”, force units are used (
lbs or kps), for “Equal rigidities” (per
unit length), length units are used (ft), and if it is “Manual input of
relative rigidity”, then they are treated as dimensionless numbers.
b) Symbols and Equations
A
consistent set of symbols has been introduced, and equations given for all
symbols, so that the source of all output data can be traced. Where applicable,
design code references also added. Note that in many cases a symbol is used
before the place in the output that the symbol is defined by its own equation.
c) Units
-
Unit
Indicators
The
Indicator of length and force units has been removed from the header, and
instead, the units are placed on all individual items in the report.
-
Force
Units Employed
Previously,
only lbs were used, even when kips is selected in the Format Settings. Now kips are used for the rigid diaphragm
results when that is the format selection.
Note that other portions of the log file continue to be output in lbs
when the selection is kips.
-
Length
Units Employed
Previously,
the program did not consistently output items in ft, as the header suggested;
some items were output in inches, and some were divided by factors like 1000
for readability. Now, feet are always used as the length units.
d) Formatting
-
The
output is now consistent in its use of hyphens (-) and colons (:).
-
The
length of the dashed line has been shortened, and all output is constrained to
remain within that line, so that it prints on one page in Notepad with a 9
font.
-
For
to the initial section of data that is output for the X-direction and the
Y-direction on the same line, the previously ragged data has been placed in two
columns, for the X-direction and Y-direction, with the letters x and y appended
to the symbols, e.g. Jx and Jy for Torsional Rigidity J. These symbols are
later referred to in the separate results for the E-W and N-S directions,
making it clear which is used for which direction of force.
e) Center of Rigidity
-
The
word “of” has been added to “Center of Rigidity”, symbol Cr and equation added,
and units shown, in ft.
-
The
Y value for centre of rigidity was displayed using scientific notation, but the
X value was not. Now decimal notation is used for both.
f) Building Dimension D
A line
for building dimension D, perpendicular to the force direction, has been added,
as this is used in the eccentricity calculations for many methods.
g) Accidental eccentricity
-
The
output “Acc Eccentricity” or “Eccentricity” has been removed for non-torsional
load cases ASCE 7 all-heights, Case 1, and ASCE 7 low-rise. Otherwise, it is
now on its own line, with “acc” fully spelled out, equation and units shown,
symbol ea for seismic or e for all
heights case 1.
-
A
note has been added to the end of this section of output indicating the design
code reference for (accidental) eccentricity.
h) Total Rigidity
-
The
symbol Kt, equation, and units employed have been added to the Total Rigidity
line. The incorrect notation “m” following the Y value has been removed.
-
Previously,
the value displayed for Total Rigidity for the “Rigidity based on capacity”
design setting was the total capacity of the shearwalls in lbs divided by
1000. Now it is expressed in lbs or kips
according to the format setting selection, without dividing.
-
The
value for the “Equal rigidity” (per unit length) setting was the length of the
shearwalls in inches divided by 1000. Now it is the shearwall length in feet,
without dividing.
-
For
manual input, it was the shearwall length in inches multiplied by the relative
rigidity input in wall view, now it is the relative rigidity multiplied by
length in feet.
i) Torsional Rigidity
-
Torsional
rigidity has been placed on its own line. The symbol J, equation, and units
employed have been added to the Torsional Rigidity label. The incorrect
notation “m^3” following the y value has been removed.
-
Previously,
the value displayed for Torsional Rigidity for the “rigidity based on capacity”
setting was the calculated value in lbs-in2 divided by 1,000,000,000 (109) Now it is expressed in lbs-ft2 or kip-ft2 according to the format setting selection,
without dividing.
-
The
value for the “Equal rigidity” (per unit length) setting was the calculated
value in in3 divided by 109. Now it is the value ft3,
without dividing.
-
For
the “Manual input” setting, it was the value in in3 factored by the
relative rigidities, also divided by 109. Now it is the same calculation in ft3,
without dividing.
-
If
the value to be output exceeds 1,000,000, then it is expressed in scientific
notation, with 4 decimal places shown. Otherwise, it is shown with no decimals,
as it is a large number.
j) Concentrated Load
Force
units and symbol F are now displayed for concentrated load, and it can be
expressed in lbs or kips. The precision
has been changed from 2 decimals to none for output in lbs.
k) Center of Load
Symbol
Cl and units are now indicated for centre of load (ft).
l) Torsional Eccentricity
For all
torsional load cases (seismic and ASCE 7 all heights wind, Case 2) , a line has
been added giving the torsional eccentricity et = Cl-Cr (center of load minus
center of rigidity) .
m) Torsions
-
Torsions
are now output on their own line, with symbol T and units (lbs-ft or kips-ft).
They are no longer output in scientific notation.
-
Separate
equations have been added for each load case showing whether a torsional
eccentricity due of Cl – Cr, an accidental eccentricity, or both, are
used. If it is a non-torsional load
case, torsions T = 0 are shown along with an explanation giving design code
reference.
n) Shearline Forces
A
section has been added giving the equations used for the torsional, direct, and
total shearline forces shown in the shearline table below.
o) Shearline Table
-
A
header line has been added to show units (ft and lbs or kips). and symbols for
all the columns. The unit employed for Rigidity depends on Shearwall Rigidity
design selection – lbs or kips for “Depends on capacity”, ft for “Equal
rigidities” (per unit length), and no unit for “Manual input” .
-
A
column has been added for the distance li from the Center of Rigidity Cr to the
shearline, as that is needed in the calculations of shearline forces.
-
Forces
used to be in pounds with 2 decimal places, now pound forces are whole numbers.
p) Output in Absence of Wind or Seismic Loading
(Change 15)
In the
Rigid Diaphragm Analysis section of the Log File, some information for wind or
for seismic analysis was being output even when there were no loads of that
type on the structure. The title for
that design type and the lines pertaining to rigidity and eccentricity were
output, but not the shearline table below. This occurred only when the
Shearwalls rigidity setting selection is not “'Use shearwalls capacity …”. The
program now omits all wind analysis when there are no wind loads, and similarly
for seismic loads.
q) Rigid Distribution Information Clearing (Bug 1852)
The
rigid distribution analysis in the log file is no longer being recorded for
each design run of the software, when it should be clearing each time. It also
no longer repeats the title and time for each building level.
r) Repetition of Rigid Diaphragm Log File Output
(Bug 1878)
The
rigid diaphragm section of the log file results were often repeated three
times, one for each iteration of the design process. Only the final iteration
is now output.
O. Installation and Documentation
a) OCX Files in Installation (Change 6)
Updated
VSPrint and VSPDF OCX files that are included in the installation to implement
the enhanced report viewer/print utility.
a) Review and Revisions
The
entire help file has been reviewed and put up-to-date with current program
operation and features.
b) Design Code References
Design
code references have been updated to the most recent design codes, particularly
the update from UBC 2003 to UBC 2006.
c) Rigid Diaphragm Analysis
The
equations for Rigid Diaphragm analysis have been added to the help file.
Shearwalls
8.0 – March 5, 2008 - Design Office 8
This version of Shearwalls implements
- the 2006 version of the ICC International Building Code (IBC 2006),
replacing the 2003 version previously in the program
- the 2005 version of the ASCE 7 Minimum Design Loads for Buildings
and Other Structures (ASCE 7-05), which replaces the ASCE 7-02 that was in
Sizer 7.0.
The IBC 2006 references the ASCE 7-05.
A complete description of design code changes
is given below. Other changes not related to new design codes are also listed.
Several problems with program operation have
been resolved; refer to the index below for bugs pertaining to seismic load
generation, wind load generation, load distribution, shearwall design, and user
input. You may need to re-examine past projects in light of these
issues.
Follow these links to the changes described in
detail below.
A: Seismic Load Generation 9
1. ASCE 7-05 Changes 9
2. Seismic Load Generation Bugs 10
B: Wind Load Generation 10
1. ASCE 7-05 Changes 10
2. Wind Load Generation Bugs 10
C: Building Model, Load Distribution, and Design 11
1. Forces for Perforated Walls 11
2. Bugs and Minor Improvements 12
D: Input 12
1. Design Settings 12
2. Site Information Dialog 13
3. Load Generation Dialog 13
4. Input Bugs 13
E: Graphical and Text Output 14
1. Elevation View 14
2. Site Information Table 15
3. Seismic Information Table 15
4. Shear results table 15
5. Hold-down and Drag Strut Table 16
F: Documentation 16
1. On-line NDS 2005 and SDPWS 2005 16
2. Design Code References 16
3. On-line help 16
a) Spectral Response Accelerations for Seismic
Design Category A
When you
enter a value of 0.04 or less as S1, and 0.15 or less as Ss
in the Spectral response accelerations portion
of the Site Information dialog, the
program assigns a Seismic Design Category of A, in accordance with ASCE 7
11.4.1, and the program uses the procedures in 11.7 for seismic design.
b) Exclusive Use of Short Period Response
Acceleration Parameters
The
program now implements the new portion of the clause ASCE-7 11.6, which allows
for use of short period response acceleration parameters from table 11.6-1 to
be used without any comparison to 1-S parameters in Table 11.6-2.
The
program checks that
1. The
period of the structure is less than 0.8Ts, given in 11.4.5, that
3.
Equation 12.8-2 was used to calculate Cs, rather than one of the
limits on Cs given in 12.8-3 to -6,
4. No
two shearlines are separated by more than 40 feet
before
allowing this provision.
c) Design for Seismic Design Category A
When
seismic design category A is chosen by the program as a result of the spectral
response co-efficients and/or occupancy category entered, the program
implements ASCE 7-05 clause 11.7 . Equation
12.8-11 and -12 which use a height-weighted distribution of seismic forces to
building mass, are replaced by equation 11.7-1, which uses 1% of the weight on
a building level.
Furthermore,
the definition of weight used is different for 11.7-1 than for 12.8-12 in that
it includes dead loads only. In the Load
Generation dialog, the program does not allow entry of snow loads and
indicates that only dead loads are to be considered as building masses for
seismic category A.
d) Response Modification Coefficient R
The
value for response modification coefficient R from Table 12.2-1 of ASCE 7-05 is now 6.5 for wall system 13, light framed
walls that are used in Shearwalls. Previously it was 6.0. As the user is able to input this value, this
affects the default value of this parameter only.
e) Redundancy Analysis
The
procedure from ASCE 7-02 for determining the redundancy factor ρ
has been removed and replaced with the procedure from ASCE 7-05 12.3.4. The following steps have been taken:
- ρ is set to 1.0 for Seismic Design Categories A, B, and C, to comply with 12.3.4.1
- ρ is set to 1.3 for Seismic Design Categories D, E, and F to comply with 12.3.4.2, but only after the program checks the following conditions:
- 12.3.4.2 a: For stories resisting more than 35% of the accumulated base shear, it determines whether it complies with Table 12.3-3 by finding the shearwall segments (not whole shearwalls) with height to width rations of 1.0 or more ( a square segment or thinner) and comparing the capacity with these segments removed with the storey capacity.
- 12.3.4.2 b - For those stories resisting more than 35% of the accumulated base shear, the number of bays as defined in this clause for light framed construction is at least 2 on each side. For this calculation, Shearwalls uses all exterior walls on a building face, and compares twice the length of these walls to the storey height.
- That the user has defined the building as being regular by checking the checkbox in the Site Information dialog. Note that this is just a temporary expedient and we expect to have automatic irregularity checking in the next release of the program.
Note
that the program does not currently consider overstrength factors, so
12.3.4.1.5 is not checked,
Since
the above calculations are based on shearwall capacity, the program iteratively
distributes loads through the structure, designs, assigns a ρ
value, and then designs again.
f) Seismic Base Shear Calculations
The
limits on the Cs value in the equations 12.8-1 and -2 for base shear
V are given by new equations 12.8-3 to -6.
The implementation of 12.8-3 was not necessary because it applies to
buildings much taller than those allowed in Shearwalls.
The
following have been implemented
- Eqn. 12.8-4, for large period T
- Eqn. 12.8-5, lower limit of 0.01 for Cs
- Eqn. 12.8-6, limit based on S1
- 12.8.1.3 – When there are fewer than 5 stories, and the user has indicated that it is a regular structure in the Site Information dialog, and given that T < 0.5 for all our structures, Cs is calculated using 1.5 for Ss
2. Seismic Load Generation Bugs
a) Vertical Seismic Load for Small SDS
The
program was not implementing the clause ASCE 7-02 9.5.2.7-2, which is now the Exception in ASCE
7-05 12.4.2, which allows the vertical
earthquake force Ev to be set to zero if the Design Spectral
Response Acceleration SDS is less than 0.125. This has been
rectified.
Note
that the only impact of this omission was a slightly conservative hold-down
force calculation for low seismic loading.
b) Seismic Shearline Forces from User-applied
Loads after Load Generation (Bug 1715)*
Generating
seismic loads on a building that has user applied seismic loads and then
deleting the generated loads, could result in seismic shearline forces that are
different than before generating loads.
a) Open Buildings
Shearwalls
no longer implements buildings with an Open
enclosure category, as it was determined that the effort to implement of the new provisions for these
buildings in ASCE-7 05 6.5.13 was not merited given the low prevalence of such
structures designed with wooden shearwalls.
We will
consider implanting these provisions for a future version of the program.
a) Wind Load Generation On Vertically
Discontinuous Walls (Bug 1797)
The wind
loads generated on an upper level wall that is not the same extent as the lower
wall, use the extent of the lower wall for the loads on the bottom half of the
upper level wall. Therefore, many configurations received more or less loading
than they should, for example:
-
A wall that is common to two blocks in plan,
but exists on an upper level on only one of the blocks.
-
Overhangs
or cantilevers
b) Load Generation after Block Size Change (Bug
1768 )
The
ridge elevation was not being properly updated upon change in block size,
resulting in inaccuracies in many aspects of load generation in this case,
including:
-
the
tributary width of wind loads
-
calculations
using mean roof height or ridge height
This
problem would be corrected if you modified the roof via the roof input dialog
after changing block size. As most users modify the blocks, then proceed to
define the roof, it rarely occurs in normal practice.
c) Flat Roof Load Generation (Bug CSW7-12)
The
program was creating both ASCE-7 Case A and Case B loads for only one direction
on the structure in the case of a flat roof, leading to unequal loading for
square structures. The program now considers only the loads in the direction of
the force for flat roofs, which have the same coefficients for Case A and Case
B.
d) Generation after Wall Move via Keyboard Input
(Bug CSW7-13)
When
loads are generated after walls are moved by changing their co-ordinates in the
wall input form, wind loads were not generated on some of the moved portions of
the walls. This affected structures such as L-shaped, U-shaped, and those with
vertical irregularities and has been corrected.
R. Building Model, Load Distribution, and Design
1. Forces for Perforated Walls
The
following changes are implemented when you choose the SDPWS (Special Design Provisions for Wind and Seismic) or IBC load generation options in the Design Settings. They are not
implemented when UBC is chosen.
a) Shear Flow at Top of Wall
The
shear flow in plf shown at the top of a perforated shearwall, intended to
display the force transmitted from diaphragm to shearwall, is now divided by perforation
factor Co to comply with the SDPWS 4.3.6.4.1.1 and IBC 2305.3.8.2.5
The
force shown is V/L/Co, where V is the total shear force imparted to the wall. Note that for consistency and static
determinacy divides by the wall length L rather than the length of full height
sheathing (FHS). The force shown at the bottom of the wall uses FHS.
This
shear flow is now reported only in the Elevation
View graphics. It has been removed from the Shear Results table of the Design Results output., and replaced
with the value using FHS that is intended for connection and connector design.
b) Base Shear
The
shear flow in plf shown at the base of a
perforated shearwall, intended to show the force used for design of collectors
and connections, is now divided by the Co factor to comply with the SDPWS
4.3.6.4.1.1 and IBC 2305.3.8.2.5. This value is V/FHS/Co.
Note
that this value previously represented the force used for shearwall design. The
shearwall design force is now presented in the text below a shearline showing
the material specification. This base
shear force is also presented in the Shear
Results table of the Design Results output.
c) Uplift Anchorage Force t
The
program now calculates an uplift anchorage force t for perforated walls to
comply with SDPWS 4.3.6.4.1 and IBC 2305.3.8.2.4.
The
program adds the accumulated t line forces, in plf, from perforated walls on
upper levels to one created on a lower level, to comply with SDPWS 4.3.6.4.4
and IBC 2305.3.8.2.4.
If
perforated wall segments are offset such that the t force from an upper floor
is distributed over an opening on a lower floor, then the force is distributed
by engineering mechanics as a point force at the support to the opening.
These t
point forces are included in the combined overturning force reported in Elevation View and in the Dragstrut and Holddown Table of the
design results. They are not combined in such a way to diminish compression
forces.
The t
line forces can appear over segmented walls or in gaps in the shearline if a
perforated wall exists on a floor above at that location.
The line
force t is reported only in Elevation
View graphics.
d) Drag Strut Forces
The
forces used for drag strut calculations for any wall segment that is part of a
perforated wall are now divided by Co, to comply with the SDPWS 4.3.6.4.1.1 and
IBC 2305.3.8.2.5. Note that two separate Co factors could go into the calculation of a
single drag strut force in the unusual case that two perforated shearwalls are
created side-by-side.
The following were implemented as a
workaround for bug 1801, which was fixed in version 8.1. These features remain
in the program.
a) Select All*
It is now possible to select all
walls while in the Wall Action in plan view for editing and moving, via a menu
item in the Edit menu. You can also use Ctrl-A keystroke to do the same thing.
b) Move Structure*
It is now possible to move the
entire structure, while the Wall action, by
a) being in the Wall action in plan
view
b) using the Select All Command
c) pressing the Shift key on the
keyboard
d) also depressing the left mouse
button
e) selecting a point in plan view
and moving the mouse in the direction of
the move.
Note that all walls are selected,
but the roof moves as well.
3. Bugs and Minor Improvements
a) Compression Force Load Combination (Bug
CSW7-19)
The load
combination 1.0D + 1.0W has been implemented for downward compression forces.
Previously, the program was erroneously using the 0.6D combination intended for
uplift forces.
b) Wall Groups Designed for Opposing
Directions (Bug CSW7-41)
The
program was not always ensuring that the wall materials designed for opposing
force directions were the ones needed for the strongest of the two cases,
instead it could design separate materials for opposing directions. It now
reports just one material wall group for the wind case, and one for the seismic
case.
c) Three Block Roof Joining (Bug 1777 )
The roof
on the middle block in a 3-block configuration, when all three blocks have the
same width, was not joining with the other two blocks.
d) Seismic Compression Force Location (Offset) (
Bug 1764)*
For
seismic design, the location of compression hold down was offset from end of
wall by twice the user input hold-down offset rather than just that offset. As
a consequence, the compression and tension hold-downs at an opening end were
offset from each other, and the program assigned some of the dead load to one
of the hold-downs and some to the other, rather than the full dead load to
both.
a) Local Building Code Capacity
Local building code capacity reduction has been changed to Local building code capacity modification.
This has been done to allow you to enter a value greater than one to model the
increase in allowable stress due to the use of the overstrength factor in
generating loads, according to 12.4.3.
This is
just a temporary expedient until the implementation of irregularity analysis in
the next release allows for the determination of overstrength factors.
a) Seismic Design Category
Removed
display of Seismic Design Category, as it was not updating immediately when
users changed other parameters in the dialog box, and it is not needed as a
data entry field. The Seismic Design Category used for load generation is
displayed in the Design Results under Site Information.
b) Response Modification Coefficient R
The
default value of the response modification coefficient R has changed to 6.5
from 6 as per Table 12.2-1 of ASCE 7-05.
c) Irregular Structures Checkbox
A
checkbox has been added to indicate that the program is an irregular structure,
a distinction needed for the implementation of several of the changes described
in Z above.
Note
that this is a temporary addition to the program, as we expect the next release
of the program to include full irregularity analysis, in which the program
automatically detects structural irregularities.
d) Building Enclosure
The
program no longer offers the choice of Open
buildings as an Enclosure option.
a) ASCE 7
Seismic Design Category A
When
Seismic Design Category A is chosen by the program as a result of user input in
the Site Information dialog, the
program disables snow load entry, and indicates via a note that only dead loads
are to be considered as building masses, to comply with ASCE 7-05
11.7-2.
a) User-applied Wind Shearline Forces (Bug 1593)
When
entering wind loads on a building face, the default extent of the load was
furthest extent of shear resisting elements in the orthogonal direction to the
wind loads, and not the length of the building face bearing those loads, when
there were non-shearwalls at the ends.
b) Default Wind Load Extent (Bug 1778)
When
checking the "Implement as a factored force applied directly", the
wind direction changes to "East to West” from "Both directions",
so that often loads were inadvertently entered only in one direction.
c) Levels in Load Input (Bug CSW7-10)
The
range of levels in the Add a New Load
input form is now synchronized with the range of levels in the Load Input form. Previously it was
resetting to 1 to the maximum number of levels in the structure. The default should be the same as the
“Levels” in the “Load Input” dialogue box
d) Wall Type Update on Change of Standard Wall
(Bug 1730)
The wall
type shading in the Plan View drawing
did not update immediately upon selection of a new standard wall.
e) Rigid Diaphragm
Loads and Forces Settings (Bug
1769)
In the
Settings->Loads and Forces section of the menu, the Rigid diaphragm check
boxes for plan and elevation view displayed the settings saved for the Flexible
diaphragm selections.
a) Select All
It is
now possible to select all walls while in the Wall Action in plan view for
editing and moving, via a menu item in the Edit menu. You can also use Ctrl-A
keystroke to do the same thing.
b) Move
Structure
It is now possible to move the entire structure,
while the Wall action, by a) being in the Wall action in plan view b) using the
Select All Command c) pressing the Shift key on the keyboard d) also depressing
the left mouse button e) selecting a point in plan view and moving the
mouse in the direction of the move. Note that all walls are selected, but the
roof moves as well.
a) Materials and Loads Specification
The
block of text that appears below the shearline has been redesigned to make it
more readable and to add information that has become necessary as a result of
the other changes to the program. The changes are
-
Reorganised
into two groups of data under bold headings for All Shearwalls, and for the Critical Segment for design. Within the All Shearwalls there are two subgroups of data, Exterior surface and Interior
surface.
-
For each surface:
-
Sheathing and fastener information combined into one
line with standard engineering format e.g. Structural
1 w/ 12d nails @ 6/12”
-
Indicates
when screws are used rather than nails
-
Shows
shear capacity on separate line for each surface.
-
Shows
C&C sheathing load and capacity on same line
-
Shows
nail withdrawal load and capacity on same line.
-
The critical segment for design is the one with the
highest ratio of load to resistance when distribution of shearline loads and
perforation factors are taken into account. This is shown for shearwalls only
-
For
the critical segment:
-
Indicates
wall segment
-
If
it is perforated segment, indicates that capacity includes Co factor
-
Outputs
design shear force in plf. Note that this was not output on previous versions,
instead you were expected to consult the base shear on the diagram. The diagram
base shear is not the design shear for perforated walls.
-
Outputs
the combined shear resistance on a separate line, along with the sheathing
combination rule used to calculate it.
-
Made punctuation and capitalisation of words more
consistent, and indentation more pronounced..
b) Perforated Wall Uplift Anchorage Force
Vertical
arrows and a plf value have been placed along the bottom edge of perforated
shearwalls to show the new perforated wall anchorage force t required by SDPWS
4.3.6.4.1 and IBC 2305.3.8.2.4.
This is
the accumulated t force from the level with the arrows plus the forces
distributed downwards from floors above, according to SDPWS 4.3.6.4.4 and IBC
2305.3.8.2.4.
A symbol
t with a value in lbs has been placed in the list of hold-down forces, when
reported separately, wherever a point t force is created because of offset
openings.
c) Perforation Factor
When a
wall is a perforated wall, the program now states this below the wall and gives
the perforation factor.
d) Factored Dead Hold-down Component
For
consistency with other forces, the program now shows the factored dead
hold-down component, factored by the load combination factor, rather than the
unfactored component previously shown.
e) Legend
In the
legend that appears in the bottom right of the screen, the program now includes
-
The
load factors employed for tension and compression forces
-
The
symbol showing perforated wall uplift anchorage force
-
Combined
holddown force expression for both
compression and tension case
-
Includes
perforation factor Co in the description of V/L/Co and V/FHS/Co descriptions
-
Adjustments
to the indication of factored vs unfactored forces and units labels to make it more clear, and
as needed to accommodate the other changes
-
Indication
that the shear overturning holddown component S has been divided by the
perforation factor Co.
a) Seismic Use Group
The
output of the Seismic Use Group has been removed, as this concept is no longer
in ASCE-7
b) Site Class
The
output “Site Profile Class” has been renamed “Site Class”, in keeping with the
terminology of ASCE 7 11.4.2.
a) Rmax and ρ
The Rmax
column has been removed for ASCE -7 design, as it is no longer part of the
redundancy factor calculations. It has been retained for UBC. The value of ρ is no longer output on each
building level, as it now applies to the whole structure.
b) Vertical Earthquake Load Note
The note
under the table explaining the effect of the vertical earthquake load has been
expanded to make the calculations more explicit, and applies to compression and
tension hold-down forces.
a) Removal of V/L
To make
space, and because this value is not used for design, data in the column
currently named V/L has been removed, and the column renamed vmax. It is still possible to view the
V/L force, that is, the diaphragm to shearwall force, in Elevation View.
b) Base Shear
The data
in the column currently named V/L has been removed, and the column renamed vmax. The
value in the column is the base shear used for collector and connection design
for perforated walls according to SDPWS 4.3.6.4.1.1 and IBC 2305.3.8.2.5. This
is the shear load on the wall in lbs, V, divided by the length of full height
sheathing VHS and the perforation factor Co = V/FHS/Co. This value is called vmax
SDPWS .
If there
is only one wall, there is only one line of output per shearline, and the value
for the wall is shown. If there is more than one wall, a dash is output for the
line, and the values for each wall underneath.
c) Legend and notes
-
The
new V/FHS/Co vmax force is given a full
explanation, with design code references
-
A
note giving the intended purpose of V/FHS vs V/FHS/Co has been added.
-
A
note directing you to elevation view for the Uplift Anchorage Force t for IBC
2305.3.8.2.6 and SDPWS 4.3.6.4.2 has been added.
5. Hold-down and Drag Strut Table
a) Factored Dead Hold-down Component
The
program now outputs the factored dead load, rather than the unfactored load,
for consistency with the overturning force. This change is reflected in the
legend below.
b) Perforation Factor Co
Now
indicates in the legend that that the shear component of the overturning
hold-down force, and the drag strut forces, include the perforation factor Co.
This perforation factor is not listed here, but a note indicates that it can be
determined from the Shear Results
table.
c) Vertical Earthquake Load
The note
regarding the dead load calculations explains more thoroughly the contribution
of the Vertical Earthquake load, as follows:
Combined
load includes vertical earthquake load of -0.2Sds x seismic load factor x
unfactored D = - #.## x factored dead load shown.
1. On-line NDS 2005 and SDPWS 2005
a) Adobe Acrobat 8
The
on-line design code now works with the most recent versions of Adobe Acrobat.
a) Welcome Box
A note
been added to both the Welcome box and giving the editions of the IBC, UBC,
Special Design Provisions for Wind and Seismic (SDPWS) and Wood Frame
Construction Manual (WFCM) used in the program, referring to the Building Codes
box for further information.
b) Building codes box
The
explanation of the implementation of these codes in the Building Codes message
box invoked from the Welcome box has been revised.
c) Elsewhere in program
All
program references to design codes have been updated, for example in the design
settings input, the design results output, and in warning messages.
a) Review
The
on-line help has been reviewed to make sure it is up-to-date with current
program operation and current design code references.
b) HTML Help
The Help
system used is now HTML Help, which is compatible with the Windows Vista
operating system, as well as previous versions of Windows
c) Release Notes
The
release notes describing all changes to the program are now in the html file New Features, which is included with the
installation, rather than in the Read Me notes.
Version 7.01 - March 5, 2007 - Design Office
7, Service Release 1
This version of Shearwalls was issued to
provide the following correction to Shearwalls 7.0.
Bug: Drag Strut Forces for Flexible
Diaphragms, Distribution based on Rigidity
Flexible diaphragm dragstrut forces were
incorrect when the "Shearwall force based on wall rigidity" was
checked, as it is by default. They were off by widely varying amounts, by as
much as a factor of 20 too great or too small or as little as a few percent. The incorrect values appeared in both the Dragstrut
and Holddowns table and in the Elevation view, on all shearlines and all levels
of the building. This problem was introduced with Shearwalls 7, and has been
corrected for Version 7.01.
Version 7.0 Design Office 7 - November 8, 2006
- Design Codes
- Design codes referenced
- Design Codes box
Updated explanation of design codes referenced in Design
Codes box accessed from Welcome box.
- References to SDPWS
Changed all references to the AF&PA AWC Special
Design Provisions for Wind and Seismic to "SDPWS" rather then
"AF&PA Supplement", and changed date from 2001 to 2005.
- Design code options
Changed "Use AF&PA AWC 2001 Wind and
Seismic Supplement and/or Wood Frame Construction Manual " option to "AF&PA
AWC Special Design Provisions for Wind and Seismic (SDPWS 2005)*"
(removed WFCM reference)
Added note: *Where no SDPWS provision exists,
the IBC provision will be used
- On-line Design Codes
- NDS On-line
An updated NDS 2005 on-line .pdf document is
accessed from Shearwalls Help menu, and status bar description.
The NDS 2005 and NDS Supplement and have been combined into one document, and
the NDS 2005 Commentary is now added in the same document.
- SDPWS On-line
Added AF&PA AWC Special Design Provisions for
Wind and Seismic (SDPWS 2005 ) document that can be accessed from the Shearwalls
Help menu.
- Special Design Provisions for Wind and
Seismic (SDPWS) Update
The provisions used for the SDPWS option have been
updated for any changes from 2001 to 2005 affecting the program. These are:
- Sheathing Combination - Fiberboard and Plywood Siding
For wind design, the program now sums the sheathing
capacities for Fiberboard and Plywood Siding when combined with gypsum
wallboard, according to 4.3.3.2 p 20. Previously, it used greatest or twice
weakest for these materials, according to SDPWS 2001 4.3.3.2.
The program no longer allows the user to enter
walls of type Perforated and of type Segmented along the same
shearline, for the SDPWS option only. This is due to a change in SDPWS 4.3.3.3
that adds the words "and construction" to the restriction on
differing materials on a shearline.
Limits of 490 plf (seismic) and 685 plf (wind) for
the capacity each side of a perforated shearwall are implemented, according to
SDPWS 4.3.5.3-2, This also reduces the existing limit of 1000 plf for a double
sided shearwall to 980 plf for seismic design.
- Fibreboard
Perpendicular to Support Bending Capacity
Perpendicular to support values for out-of- plane
sheathing bending from Table 3.2.1 p9 have been added to the program,. The
horizontal sheathing option is now activated for fibreboard materials when
SDPWS selected. This affects wind C&C design.
- Removal of WFCM provisions
The program no longer used Wood Frame Construction
Manual provisions, except where no IBC or SDPWS provision exists, and for
bending capacity for plywood siding for wind C&C design.
Refer to the on-line Help for details.
Therefore, the following changes were made to the
program:
- Regular Cellulostic
Fiberboard Sheathing
This material was removed from the program for the
SDPWS option. Structural fiberboard remains.
- Minimum
Height-to-Width Ratio for Lumber Sheathing
The SDPWS option minimum height -to-width ratio for
horizontal lumber sheathing is now 2:1, whereas in Shearwalls 2004 it was
3.5:1, on the recommendation of AWC.
- Sheathing Material
Names
The names of sheathing material names have been
changed to reflect the terminology in SDPWS 2005.
- Building Model
- Undo/Redo Feature
The program now allows the user to revert graphical
input operations in the interactive Plan View and data input operations in its
associated input forms, and to restore the actions that were undone
- User Control
An Undo and a Redo button are added
to the control bar above the Plan View window. These items are also placed in
the Edit menu. In addition, the keystrokes Ctrl-Z and Ctrl-Y activate
the undo and redo commands, respectively.
- Affected Views
This feature is active in the Structure, Walls, Openings, and Roofs
actions, in both Plan View and its associated data input forms. It is
not active in the CAD Import, Site Dialog, Load
Generation Loads and Forces
- Affected Operations
Operations that create a change to the physical
structure of the building are affected, such as moving or resizing blocks,
walls, openings and roof panels, or changing the material composition of walls.
Merely moving the mouse, selecting a new object, or
navigating amongst input controls, and changing building levels or views, are
not included. Changing certain input controls that have no immediate effect on
the building, like Roof slope - Opposites the same are also not
included.
- No. of Consecutive
Undo's
As many as five consecutive operations can be
undone, and redone again.
- Interaction with
File Save Command
The undo sequence is preserved through File Save
commands, so that the user can undo and redo after saving. A document that has
an operation undone then redone is still considered a changed document by
Windows.
- CAD Import, Upper Levels
This version extends the ability to import a
Windows metafile exported from CAD software to the upper levels of the
structure. Previously only the first level footprint could be imported.
- CAD Import Wizard
The Wizard has been expanded to be a CAD Import
Input View, similar to the other input views, that controls the file input for
each level. It also continues operate as a wizard that guides you through the
positioning and scaling process.
- Drawings Required
If you choose not to import a metafile for a
particular level, the metafile for the floor below will be shown. The first
level file is required.
- Scaling Factors
You can choose to bypass the scaling operation for
any level but the ground level by specifying that any upper floor metafile has
the same scaling factor as the level below.
- Display
Once the input, positioning, and scaling process is
complete, the metafiles for a particular floor will be visible in any other
action of Plan View, when you press the CAD Import button.
- Six Levels
Shearwalls now allows input of buildings to a
maximum of six levels, as opposed to the four levels previously allowed. This
allows for the maximum of 5 levels allowed for certain structures in IBC (Table
503), plus one below-grade level.
- Structure Input
The spin control which is used to create the
number of levels on each block now has an upper limit of 6 rather than 4.The Structure
input dialog has two additional levels for which wall height and floor/ceiling
depth can be entered.
- Graphics
The Levels controls in Plan View and Elevation View
now have an upper limit of six levels rather than four. Elevation view can now
display all six levels at once.
- Data input
The Generate Loads View,
Load Input View, and Add
load dialog filters for input and viewing loads now extend to 6 levels.
- Text output
All Design results tables have been expanded to
show more sections of data corresponding to building levels, and/or show levels
up to 6 rather than 4 in the Level column:
- Loads and Forces
An incomplete implementation of compression forces,
and of separate cases of accumulation of vertical overturning forces for the
opposing horizontal force directions, appeared in version 2004c of the software
with Design Office 2004, Service Release 2.
This implementation was not recorded in the Readme
files for that version, and has been improved for this version, so the complete
description of the feature is given here.
A setting has been added to the Default Settings
page allowing input of the distance from the end of a wall or opening that a
hold-down can be located. It can be saved for a particular project, and as a
default value to be used for new files. The "original" setting is
3".
- Minimum offset;
contiguous walls
A value of zero cannot be entered, so there must be
some hold-down offset. This means that compression forces at the end of one
wall are not at precisely the same location as tension forces at the end of the
other. In Sizer 2004b, these forces were cancelling.
- Hold-down magnitude
The program uses the full length of the wall to
calculate the moment arm for hold-down force magnitude calculations, not the
reduced distance between hold-downs. There should be no chance in hold-down
force magnitude due to the offset from Shearwalls 2004.
- Compression
hold-downs
Starting with version 2004b, compression hold-downs
have been added to the program. Depending on the force direction the user
wishes to view, the program displays a compression overturning force at one end
of the wall segment and a tension force at the other. Dead loads increase
compression forces and diminish tension forces.
- Vertical force
accumulation
Where a compressive force lines up with a tension
force on the floor below, such as for offset openings, the program now
correctly uses the difference between these forces as the resulting force.
Previously it was adding the magnitude of the tension force in one direction to
the tension force in the opposite force direction.
The program now implements opposing force
directions for seismic loading in order to distinguish the locations of tension
and compression forces for these directions. The implications of this are
discussed in the sections on Plan View and
Elevation View
below.
Since the design shear force is identical in both
directions, there are no implications for shearwall design.
- Distribution of Load Along Shearline
The program now allows users to use the relative
rigidity of shearwalls to determine the proportion of shear force taken by each
wall for all shearwall rigidity options of and for both rigid and flexible load
distribution.
- Shearwall Rigidity
Design Setting
The data group formerly called Rigid diaphragm
design is now called Shearwall rigidity. The checkbox Design
shear force based on shearwall rigidity is now active for each of the Shearwall
rigidity options - Manual input, Equal rigidities or Use
shearwall capacity.
- Flexible Diaphragm
Distribution
The Design shear force based on shearwall
rigidity setting now applies to both Rigid Diaphragm and Flexible
Diaphragm methods
- Shearwall Rigidities
For rigid diaphragm analysis, the Shearwall
rigidity options apply to the distribution of loads to shearlines, and to
the distribution of force within a shearline, if the Design shear force ... box
is checked. For flexible diaphragm analysis, these options apply to the
distribution of forces within a shearline only.
- Rigidity Based on
Shearwall Capacity
Rigidity based on shearwall capacity is now active
for the distibution of forces within a shearline, to take into account
different rigidities of perforated walls along the line. If the wall has not
yet been designed for the flexible diaphragm procedure, then the relative
rigidities are based on relative perforation factors. In doing so, the program
neglects the case where the maximum capacities are limited for perforated
shearwalls by IBC 2305.3.7.2 -1 Or SDPWS 4.3.5.3-2.
- Loads and Forces Entry
The program now requires entry into Loads and
Forces action before proceeding to the Design command, and upon
first entering the Loads and Forces action, provides the user with
advice as to which types of manually entered loads might be required.
- Main Action Sequence
The Design button and menu item will remain
disabled until you first enter the Loads and Forces action. A message
will appear when you first enter Loads and Forces as follows:
- Message, Loads not
Generated
If loads have not been generated in the Load
Generation action, the message reminds you to generate loads, and then
advises about
- dead and uplift
loads for hold-down calculations
- using direct
shearline forces to model buildings adjoining other structures
- Message, Loads
already generated
If loads have already been generated, the program
provides the same advice about dead, uplift loads and direct shearline forces,
and also about the following loads that cannot be generated:
- from large
installations, parapets, etc
- from complicated
roofs
- Direct Shearline Forces Label
The label in the group box in the Add Loads
dialog that currently says Implement as a factored force applied directly has
been changed to Add as a factored force directly (parallel) to the
shearline.
- Load Generation Commands
For Shearwalls 2004c, the Generate and add to
Loads button was removed from the Load Generation input view. This
button allowed load generation on a level-by-level basis, with different
parameters on each level. The remaining buttons were called Generate loads and
Delete all generated loads.
This button has been restored, and the three
buttons have been renamed to make their functionality more clear. They are now Generate
loads on selected levels, Delete all generated loads, and Delete all and
regenerate
- Snow Load for Building Mass
The input of snow load component of the seismic
building mass for roofs in both the Default Settings and the Load Generation
input view was a source of confusion for some users. This has been improved as
follows:
- Proportion of snow
used setting
A setting called Proportion of snow used has
been added to the Default settings. This is originally set to 20% for
IBC (1617.5.1) and SPDWS (ASCE 7 9.5.3.8.1) design code options, and 25% for
UBC (1630.1.1). It is reset if you change the Design Code Design
setting and exit the settings.
- Explanatory note
In Generate Loads view, the program explains the
input value with a note stating what percentage is included using the above
setting.
- Default snow mass
Previously the default snow mass for a new
installation was 6 psf, and the program included only the percentage of
required by the design codes, leading to snow masses much less than the minimum
needed for inclusion in building mass calculations. The "original
settings" default snow mass is now 40 psf.
- Maximum contribution
The program continues to include the snow load
contribution only if the total snow load is less than 30 psf, in accordance
with the design code clauses referred to above.
- ASCE 7 Seismic Design Category
The seismic design category depends in a complex
way on the Occupancy, S1, SS, Fa, and Fv values in the ASCE 7-02. It is used in
the Shearwalls only for warning messages regarding height limitations
for the seismic procedure, but is of interest to the engineer for determining
allowable design procedures and structural irregularities
The program now shows this value in the Site
dialog. Entering or selecting values in the Occupancy, S1, SS, Fa, or Fv fields
will cause an immediate change in the Seismic Design Category if one is
warranted.
- ASCE 7 Case 2 Load Distribution
ASCE 7 case 2 wind shear forces on the top storey
of a multi storey structure were twice the magnitude they should be.
- Graphics
An incomplete implementation of several of the
items below, such as hold-downs, force direction,
and compression forces appeared in version 2004c of the software. This
implementation was not recorded in the Readme files for that version, and has
been improved for this version, so the complete description of the graphical
presentation of these forces is given here.
- Legends
Explanatory legends explaining the meaning of the
symbols used for loads and forces in Elevation View and in Plan View have been
added. Separate legends appear for wind and seismic design, and for Loads
and Forces action versus Generate Loads action
- Elevation view
A legend is added to the bottom right corner of the
view. It shows the symbols for tension and hold-down forces for shear
overturning, dead, uplift and combined, hold-down magnitudes; load combination
factors; shearline forces; the meaning of the various shear force arrows, and
the symbol for dragstut forces. Slightly different legends appear for seismic
and wind output.
- Plan View, Loads and
Forces Action
A legend is added to the bottom left corner of the
view. It shows the symbols for shearline forces, holddown forces, compression
forces, vertical elements, applied shear loads, dead loads, uplift loads, and
discontinuous shearline forces applied as loads.
- Plan View, Generate
Loads Action
A legend is added to the bottom left corner of the
view. It shows the symbols for generated shear point loads and line loads,
generated building masses, and floor areas for mass generation. Forces or
user-applied loads are not shown in this action.
- Factored vs
Unfactored Loads and Forces
When the legends indicate that loads and forces are
factored or unfactored, it means that they are or are not multiplied by the
load combination factor entered in the Design Settings and seismic
redundancy factor calculated by the program. Factored dead forces also include
the ASCE 7 vertical earthquake load.
- Force Direction
- Seismic Direction
The Show menu and the Loads and Forces settings
now allow you to choose which direction to view seismic forces.
In Elevation view, the Seismic
selection now contains a submenu with the two directions, based on the
shearline chosen. The direction of the shear force arrows is reversed for the
two directions and the locations of the tension and compression forces are
interchanged.
In Plan View, two of the four selections of
the Load Direction choices currently available for wind are available
for seismic, allowing hold-down forces to be shown in those directions. The
loads and shearline forces are still shown as bi-directional arrows.
- Critical Forces
The Critical Forces choice under Load
Direction in Plan View, previously available only for
low-rise wind loads, is now active for all wind and seismic loading. It shows
shearline forces in both directions, and the critical tension hold-down force
at each vertical force collector location. For low-rise wind loads, it still
also shows the critical force for all reference corners.
This item should be selected if you want a drawing
showing all of your hold-down forces in Plan View.
- Hold-downs
- Occurrence
Hold-downs are now shown only on the tension side
of the overturning force for the chosen force direction, in both Plan View and
Elevation View. Compression forces are shown on the other side. To see all
the tension forces in one drawing, choose the Critical Forces Show menu
item under Load Direction
- Position
Hold-downs are now moved inside the wall by the holddown
offset distance, and compression hold-downs can no
longer coincide with tension hold-downs.
- Appearance
Hold-downs are now drawn as triangles at the top
and bottom of a joist area in Elevation View, connected by a line, to
distinguish them from compression forces. Previous to 2004c, they were arrows
attached to a circle. In Plan View, they appear as small triangles
(previously they were circles.)
- Vertical
discontinuities
Hold-downs from the floor above now appear on the
level when there are no walls on that level, carried through by a vertical
element.
- Compression forces
- Occurrence
Compression forces are drawn whenever the net force
is directed downwards, even in the case that downward dead load dominates
upward overturning force. These forces were not shown when tension hold-downs
only were implemented.
- Position
Compression forces are also moved inside the wall
by the holddown offset
distance, and compression
hold-downs can not coincide with tension hold-downs.
- Elevation View
Symbol and Text
A vertical arrow symbol is used to distinguish
compressive forces from hold-downs, and has been extended downwards through the
joist area. The negative sign is no longer shown for these forces. The holddown
magnitude text is now positioned such that the adjacent compression and tension
forces do not overlap.
- Plan view symbol
In Plan view, compression forces are shown
by a circle and the letter C. No magnitude is shown, as the force does not
include other gravity load combinations and is thus not of sufficient interest
to merit the clutter on the screen.
- Display control
Compression forces are displayed based upon the Hold-down
item in the Show menu and the Loads and Forces settings page
- Vertical
elements
- Location
Vertical elements are created wherever a holddown
or compressive force is created, and it does not coincide with a wall or
opening end (plus or minus hold-down offset) on the level below. They
correspond to either columns or strengthened wall studs.
- Depiction in
Elevation View
This is depicted as of two light solid lines spaced
3" apart, and a dotted line in the middle of them, representing a built-up
double wall stud. The element centred on the hold-down of compression force,
except where walls meet as described below.
The element extends from the bottom of the upper
floor joist to the top of the lower joists, except over openings, where the
element extends down to the opening top.
- Depiction in Plan
View
In Plan View they appear as small squares, the same
width as a wall, with a dark blue colour (dark red when a wall is selected).
They replace the hold-down or compression force symbol where they exist.
- Contiguous walls
When two forces exist where segmented walls meet,
usually tension and hold-down forces separated by twice the holddown offset,
the program depicts only one vertical element, centred between the forces.
- Display setting
You are able to turn on and off the display of
vertical elements via Settings... Display, separately for Elevation
View. This display setting is not currently implemented in the Show
menu.
- Horizontal Forces
- Shearline Point
Force
In Elevation View, shearline force arrow has
been reduced in size, includes the entire tail, and no longer goes missing when
there is a gap in the walls at the end of a shearline.
- Diaphragm Shear Flow
The diaphragm shear flow at the top of the diagram
now extends the entire width of the shearline, from the extreme exterior wall
at one end to the extreme exterior wall on the other, through all gaps in the
shearline, and over openings and non-shearwalls. Previously it was incorrectly
shown over walls only.
- U-shaped Buildings
When there is a gap in the shearline that is
actually external to the building, due to a structure that is U-shaped in plan
or in elevation, the program continues to show the diaphragm shear flow across
the gap that is absent a diaphragm and also drag strut forces leading into the
gap.
This indicates more clearly to the user that the
program does not yet deal correctly with this situation from a load analysis
standpoint. The WoodWorks development team is working on a solution to this
problem, and suggestions from users on how to distribute loads in such
structures are welcome.
- Drag Strut Forces
The drag strut forces that occur at wall ends have
been moved up closer to the top of the wall. All the forces have been provided
with a circle at one end to distinguish them from shearline forces and to
emphasize that, like tension hold-downs, a mechanical connection is required.
- Elevation View Title Block
- Layout
The large amount of empty space above the title bar
in Elevation View has been reduced to the size of a reasonable margin.
- Title block
The title block has been reconfigured differently
for printing and for screen display. It now shows,
On the first line in print mode,
"Elevation
View"
On the second line in print mode, first line in
screen mode
shearline
name
shearline
location
building
levels shown
On the third line, in print mode, still on the
first line on screen
rigid or
flexible design case
wind or
seismic design
- Opening Colour due to Gray Block
Outline
The gray outline of blocks and roofs is no longer
being drawn over walls, and openings. It was discolouring walls and obscuring
openings.
- Text Output
- Legends
Explanatory notes have been added to the following
tables, indicating the meaning of all abbreviated items in the text headings
and providing further information on the interpretation of the data in the
tables.: Wind Shear Loads, Dead Loads,
Uplift Loads, Building Masses, Seismic loads, Wind Shear
Results, Seismic Shear Results, Wind Dragstrut
and Holddown Forces, Seismic Dragstrut and Holddown Forces.
- Design settings
The "Wind Standard" box in the Design
Settings now indicates the ASCE 7 wind load generation method (low-rise or
all-heights).
- Dead Loads and Uplift Loads
We have removed the "Name" label and the
output of the dead load name.
- Seismic Loads and Building Masses
In the Seismic Loads and Building Masses
column under Force Dir, changed e.g. E->W to E-W, without the arrow.
The heading "Shear Line" was changed to "Wall Line"
- Dragstrut and Hold-down Tables
Compression forces are not shown in these tables,
just tension hold-downs. This is mentioned in the legend.
- Wind Load Cp value in Log
File
The log file output has been updated to show 2
digits after the decimal point for the pressure co-efficient Cp rather than one.
This change accomodates new coefficients for ASCE 7 02 such as 0.15.
- Shear Results Table - Shear Force (V/L)
In the shear results table, the diaphragm shear
force V/L was being reported for each wall, although it applies to the entire
shearline. The V/L is now only reported for the shearlines.
- Shear Results Table Shearline Allowable
Shear V
If a perforated wall exists on a shearline, the
allowable shear (V) reported for shearlines was applying the limiting
perforated wall capacity to all the walls on the shearline, including segmented
walls, when summing up the individual wall capacities along the shearline for
design.
- Program Operation
- Site Information Crash - UBC 97
Shearwalls was crashing, when the Site Information
button was invoked with UBC 97 selected in the Design Settings.
- File Save Flag
After a large number of user operations, the
program was not indicating to Windows that a project file had been modified,
leading to cases where you could close a file without being notified to save
it. This has been rectified.
- Standard Wall Selection
When a wall is selected in Shearwalls which has
materials corresponding to a standard wall; the standard wall's name was not
correctly selected in wall input view. Instead, it showed as blank. This has
been fixed.
- Bug Fixes
- Load Generation
UBC Site Information Crash
Shearwalls was crashing
when the Site Information button was invoked with UBC 97 selected in the Design
Settings.
ASCE 7 Case 1 / Case 2 Load
Distribution
ASCE 7 02 Case 2 wind shear forces on the top
story of a multi-story structure were twice the magnitude they should be.
- User Interface
Grey Block and Roof Outline
The grey outline of blocks
and roofs is no longer being drawn over walls, and openings. It was discoloring
walls and obscuring openings.
File Save Flag
After a large number of
user operations, the program was not indicating to Windows that a project file
had been modified, leading to cases where you could close a file without being
notified to save it. This has been rectified.
- Shear Results Table
Shear Force (V/L)
In the shear results table,
the diaphragm shear force V/L was being reported for each wall, although it
applies to the entire shearline. The V/L is now only reported for the
shearlines.
Shearline Allowable Shear V
If a perforated wall exists
on a shearline, the allowable shear (V) reported for shearlines was applying
the limiting perforated wall capacity [LINK] to all the walls on the shearline,
including segmented walls, when summing up the individual wall capacities along
the shearline for design.
Version 2004d Design Office 2004 Service
Release 2a - August 23, 2006
- Framing Material in Output and Design
Starting with version 2004c
(Service Release 2)
the framing material and its specific gravity as reported in the Materials
table of the design results report, and the resulting shear capacity, was
always Douglas Fir-L regardless of the material input by the user. In the Elevation
View diagram, the material input by the user was shown, despite the fact
that Doug-fir values were used in design.
- ASCE 7 Minimum Wind Loading
The following problems with ASCE 7 minimum
wind loads, implemented for
version 2004c (Service Release 2), were rectified:
- For ASCE 7 low-rise wind loads,
if the minimum load option is selected, then wind loads are generated
using the minimum pressure of 10 psf even if this is less than the
windspeed-generated loads. This separate load case is indicated via
a subtitle and note in the Shear Results tables in the design output. The
user must compare these results with the windspeed-generated results by
running the two load cases separately. This is necessary because end zone
effects can create different critical cases on particular
shearlines.
- The 10 psf minimum wind loads were
incorrectly applied to both surfaces of the structure in a given
direction. The minimum wind loading has been changed to apply a 5 psf
minimum load on each face if the total load on both faces, divided by the
area of one of the faces, is less than 10 psf.
- The minimum wind loads are now applied
to all surfaces on a storey, not just those that are under the 10 psf
limit. For example, if the average projected load on the upper storey is
9 psf, derived from 8 psf on the wall and 11 on the roof, 10 psf is applied
to both the wall and roof.
- Minimum wind loads for
triangular-shaped roof panels were being created as uniform loads using
the maximum tributary width of triangle, causing gable ends and hip
roofs to have rectangular load profiles.
- Minimum wind loads were not being
created on roof panels when the windspeed generated loads were excluded
due to ASCE 7 Fig 6-10 Note 6. These areas are now being taken into
consideration for minimum wind loads.
- When the all-heights
windspeed-generated loads were negative on the roof and positive on
walls, then the minimum wind loads were created the same way, when they
should have been positive loads..
- The calculations of surface area to
determine whether minimum wind loads are to be applied were mistakenly
including the bottom half of the first level walls, for which no loads
are created because they are not tributary to the first level diaphragm.
- The Apply ASCE 7 10 psf minimum wind
loads... checkbox has been moved to the load generation view, and
reworded. It now changes depending on whether the low-rise or all-heights
method is selected.
- The default value of the apply minimum
wind loads checkbox has been changed to On for ASCE 7 all-heights
method, and Off for ASCE 7 low-rise method.
- Rigid diaphragm Case 2 all-heights
loads (torsional effects, 75% loading) are no longer affected by the ASCE
7 minimum wind loading.
- The Apply ASCE 7 10 psf minimum wind
loads.. checkbox is now disabled if the user has excluded building
surfaces from wind load generation. This load case is now compared only
with loads generated on the entire structure.
- The calculations to determine whether
minimum wind loads are to be applied now correctly take into account
whether the user has selected "Exclude roof portion covered by other
roof". If this is selected, these portions are not considered in the
calculation of projected area.
- Seismic Load Regeneration Crash
When both the actual floor joist depth and the
default floor joist depth are zero, the program would crash when regenerating
seismic loads.
- Zero-overhang roof wind loads
When generating loads on the side panels of gable
end roofs with no overhang, extra tiny loads were sometimes showing up at the
edges of the roof in Plan View. They no longer appear.
- Regenerate Loads button
Removed the two load generation options Generate
and Add to Loads and Regenerate Loads from the Generate
Loads dialog and replaced them with one option - Generate Loads. The
difference between these two options was slight.
Version
2004c Design Office 2004 Service Release 2 - July 5, 2006
- ASCE 7-02
The following changes are for the update of the
software to implement ASCE 7 -02 wind and seismic load generation provisions in
place of those from ASCE 7-98.
- General
- ASCE 7-98 / -02
references
Changed the reference from ASCE-7 98 [sic]
or ASCE 7-98 to ASCE 7-02 in the Building Site dialog, the
Welcome dialog, the Design Settings dialog, in some warning
messages, and in the design standard section of the results output.
- Wind Loads - General
Minimum wind loads, from Section 6.1.4.1-2, p.23,
had not been implemented for ASCE 7-98. Analysis showed that except for very
heavy wind loading in excess of 100 mph, MWFRS minimum wind loads would govern
on many surfaces, so were added to the program. For C&C loads, minimum wind
loads rarely if ever govern, but were added anyway.
- Minimum Wind Load
Option
A checkbox was added to the Wind load generation
data group of the Site Information dialog below the Enclosure
control, called Apply minimum wind loads if greater than generated loads. This
allows users to opt out and use the actual loads, or to mix-and-match minimum
and actual loads.
- MWFRS Minimum Wind
Load Generation
The program determines if the generated loads on an
entire face of the building are less than those derived from 10 psf minimum
pressure applied over the same area. If this is true, the program will then
check the total loads on each story and change those story loads that are less
than 10 psf. This ensures that design for each story uses the governing load
case, but may create conservative design for lower stories.
- Load Cases for
Minimum Wind Loads
The procedure will be applied independently for
each load case for both the All-heights (Case 1 and Case 2) and Low-rise (load
directions and corners) load generation methods.
- Text Output
The program will indicate the minimum loads in the Wind
Shear Loads list of the text output, displaying a design note below
the table, saying
Loads on the [north, east, south, west ] faces
based on 10 psf minimum wind pressure as per ASCE 7-02 Section 6.1.4.1.
- Minimum C&C
loads
C&C loads are compared with the 10 psf minimum
pressure upon creation of each load and set to minimum if they are less.
- Exposure Categories
ASCE 7 Section 6.5.6, p 28, and Commentary 6.5.6 p
277 have been implemented as follows:
- Removal of Exposure
Category A
Exposure A will be removed from the program as it does not
exist for the UBC procedure, and is not an option for ASCE 7-02. This
exposure on longer appears in the Site Information dialog for the ASCE-7
choices of Wind Load Design Code, which apply when IBC or AFPA
and WFCM are selected as Design Codes in the Design Settings.
- Existing Files with
Exposure A
A warning message appears when project files from
previous versions are opened, if those projects had Exposure A when created
with previous version of the program. The message gives an explanation from the
ASCE 7-02 about how to handle buildings surrounded by tall structures.
- Unusual Exposure
Conditions
A status bar message is displayed at the bottom of
the main program window when the focus is on the exposure control, saying
Shearwalls does not allow separate exposures for
each wind direction nor does it interpolate exposures in transition
zones.
This refers to clauses 6.5.6.1 and 6.5.6.3, which
have not been implemented because they apply to unusual situations and require
detailed input.
- All-heights Wind Loads
- All-heights Load
Cases
- Load Cases
Implemented
Of the Cases 1-4 given in Section 6.5.12.3, p 32
and Fig 6-9, Page 54, the program now implements:
- Case 1 (full,
non-torsional loading for each orthogonal direction independently),
for both rigid and flexible diaphragms design
- Case 2
(partial torsional loading for each orthogonal direction
independently) for rigid diaphragm design.
Cases 3 and 4, with diminished loading in each
direction simultaneously, have not been included. Analysis showed would
not govern for structures modeled by Shearwalls, which analyses each direction
independently.
The previous version of the program handled only
Case 1, for both rigid and flexible analysis.
- Rigid Diaphragm
Load Case Option
A design setting called ASCE 7 all-heights wind
load case has been added to the Rigid diaphragm analysis data group
in the Design Settings. The choices are:
- Case 1 - Full
loads, no torsion
- Case 2 - 75%
loads, torsion.
This allows for the choice of Case 1 or Case 2
loading for Rigid Diaphragm design. The program is not at this stage able to
generate both sets of loads and compare the designs automatically.
The new setting is disabled unless ASCE-7
02 All-heights is selected as the Wind load design standard. The
remainder of items in the box have been enclosed by a data group called Shearwall
rigidity.
- Load Case
Designation
- Load List in Load
Input View
In the loads list of the Load Input view the
column "A/B" has been renamed "LC" for Load Case,
and '1' or '2' be used for each load according to their load case.
- Load List in Text
Output
In the Wind Shear Loads table will list
loads of both all-heights cases in the same table, sorting the loads with
respect to load case as it currently does for low-rise load cases. In the
Load Case column, which previously was blank, a '1' or '2' appears.
- Design Results
In the Shear Results table, and the Dragstrut
and Holddown Forces table the Load Case column will show the load
case for the critical wind design shear as a number for all heights loads,,
i.e. as '1' or '2' for Load Case 1 and 2, respectively.
- Rigid Analysis Note
If the Design Standard in the Design
Settings is ASCE All-heights, a note will appear underneath the main
Rigid Diaphragm Analysis title for wind design giving the method (Case 1
or Case 2) used, design code references, an explanation of the torsional moment
used, and instructions on how to change to the other case.
- Generation of Load
Cases
- Generation of Load
Cases for Diaphragm Types
The program now generates different sets of loads
for Rigid and Flexible diaphragm distribution, and sets the Distribution
Method accordingly. If Case 2 is selected for Rigid diaphragm distribution
in the Design Settings, the loads have 75% of the magnitude of Case 1
loads.
- Combination with
User-input Loads
User-input flexible loads are combined with Case 1
loads only for flexible design. User-input rigid loads are combined with
generated rigid analysis loads, whether they are Case 1 or Case 2.
- Distribution Method
Input
Since generated all-heights loads now have a
different value for Case 2 rigid diaphragm loading, the user can now designate
the distribution method for user-input loads to be combined with these loads,
or when editing the generated loads.
- In Load Input View
Currently the program activates the Distribution
method (direct forces) input field only for manually entered shearline
forces. For all other loads, this Distribution method is disabled and
set to Both. The new implementation modifies this behavior when
the Design Standard is ASCE All-heights as follows.
- sets the
Distribution method for each generated wind load according to its
load case
- disables the
control when generated wind loads are selected
- removes (direct
forces) from the label
- enables field for
all user-created wind shear loads.
- In Add Load Dialog
Currently the program activates the Distribution
Method input field only for loads created as direct forces by checking the Implement
as a Factored Force Applied Directly checkbox. Now the field is enabled
when the Wind Shear is selected as the Type and current design
standard is ASCE 7 All-heights. This will allow the user to add loads
for rigid diaphragm and flexible diaphragm independently, because for Case 2,
the corresponding generated loads have a different magnitude.
- All-heights Load
Display
When generated All-heights loads are present, the
following changes have been made to the existing Show Menu in Plan
View
- The main menu item
currently called Load Direction is called MWFRS Direction
.
- The choices for
the Wind Load Case item (formerly Wind Direction) are Case
1 and Case 2.
- Loads Displayed
In Plan View and Elevation View, the
program displays either Case 1 or Case 2 loads on the screen. but
not both, as follows:.
- If Flexible is
chosen in the Show...Forces menu, or Rigid is chosen and
Case 1 is chosen in the ASCE 7 all-heights wind load case setting,
then Case 1 loads are shown.
- If Rigid and
Case 2 are chosen, then Case w loads are shown.
If the user is viewing Rigid
Diaphragm loads, and changes between Case 1 to Case 2, the
program asks the user whether they wish to regenerate the loads they want to
view.
- Case 2 Loads and
Torsional Moment
Case 2 loads appear as 75% of Case 1 loads - only
the magnitude is different than Case 1, not the distribution. The program also
displays the critical positive and negative values of the torsional moment in
each wind direction in the bottom right corner of the screen.
- Shearline Forces
Shearline forces are created separately for each
case using the corresponding distribution method, and the shearline force for
the selected case will be displayed. The critical force for all load cases will
be shown when that menu item is selected.
- Horizontal Force
Distribution of All-heights Loads
- Case 1 Loads,
Flexible Diaphragms
There is no change to the program behavior in this
case - it uses the flexible diaphragm procedure.
- Case 1 Loads, Rigid
Diaphragms
If Case 1 - Full loads, no torsion is
selected, the program distributes the full Case 1 loads using rigid diaphragm
analysis that distributes loads based on relative rigidities of the shearlines.
It does not apply any torsional moment.
- Case 2 Loads, Rigid
Diaphragms
If Case 2, 75% loads, torsion is selected,
the program distributes the Case 2 loads, which were factored by 75%, using
rigid diaphragm analysis which distributes forces based on relative rigidities
of the shearlines. It adds a torsional moment as follows:
- for rigid
structures (Dynamic analysis not checked in Site dialog) - based upon
the total loading multiplied by 15% of the building width
- for flexible
structures (dynamic analysis) user-input eccentricity as described in I.C.7.
It does not apply the eccentricity used for
rigid diaphragm analysis in previous versions of Shearwalls - the load
eccentricity plus 5% accidental eccentricity.
The program allows for user input of torsional
eccentricity for flexible structures (dynamic analysis), derived from a manual
calculation of equation 6-21 (p. 33) which involves a calculation of the centre
of "elastic shear", the centre of mass, and many other parameters
regarding turbulence, etc. Note that "flexible structures" is not the
same thing as "flexible diaphragm".
- Input
Two edit boxes have be added to the Site
Information dialog for the input of the torsional eccentricity when the
user has checked Dynamic analysis (flexible buildings), one for each
principal direction. They are enabled/disabled according to whether the Wind
Load Design Code is ASCE-7 All heights and the ASCE 7 all-heights
wind load case is Case 2 - 75% loads, torsion.
- Defaults and
Storage
The user input eccentricity values are saved to
project file. The default values are 15% of the building width in the directions
in question.
- Vertical
Distribution of Rigid Diaphragm Forces
For rigid diaphragm distribution, the program
currently gathers all the shear forces distributed using the flexible diaphragm
method and applies them as loads to the floor below. This is a means to avoid
compounding the accidental eccentricity effect. This was no longer possible for
the new system because the rigid and flexible loads have different magnitudes,
and the user can enter rigid and flexible loads independently. For the
all-heights procedure, the program now collects all the loads designated as Rigid
Diaphragm applied on all levels above the current one and adds them to the
current level's rigid loads before calculating and distributing the shear
forces. This is possible because the shearline force distribution system is
based entirely on the rigidity of the shearwalls and not the eccentricity of
loading.
- All-heights
Coefficients (Figure 6.6)
- -0.18 coefficient
In ASCE 7-02 Fig 6-6, Page 51, a second coefficient
of -0.18 was added where in ASCE 7-98 there was no co-efficient, that is,
for
- the windward
surfaces for normal-to-ridge wind direction for certain combinations
for roof slope angles and h/L ratios, all of which are between 12
degree and 25 degree slope
- all coefficients
for normal-to-ridge slopes under 10 degrees and in the parallel to
ridge wind direction for all roof angles.
The program now uses the -0.18 co-efficient instead
of the large negative co-efficient on windward surfaces.
- Interpretation of
Note 3
Note 3 was not changed from ASCE 7-98, and still
refers to positive and negative pressures, where now there are two negative
pressures in some cases. We have interpreted this note to read:
"The roof structure still has to be designed
for both conditions - positive and negative pressures where -0.18 is
considered positive when compared with its larger negative co-efficient. "
Where no second coefficient existed for ASCE 7-98 ,
version 2004a of the program used the single large negative co-efficient
rather than zero, which we now believe was the original intention of ASCE7 98
Note 2. Therefore the program no longer generates large windward back-pressures
for certain wind angles - the critical shearline force almost always results
from using the smaller coefficient, leading to forces in the same direction as
the wind loading.
- Exceptions
Analysis showed that the larger negative
coefficient could govern for a small subset of buildings. The following note
was placed in the Design Results output to warn against such a scenario:
WoodWorks Shearwalls always uses the positive (or
smaller of negative) Cp coefficients in ASCE 7-02 Figure 6-6. For very large
structures (>100 ft) with very short upper stories (< 4ft) and low roof
angles (< 15 deg.), the larger of the negative coefficients could govern the
design of walls on the upper story. For such a case, enter loads manually.
Note 9 is new to ASCE 7-02, and states that the
total horizontal shear shall not be less than that determined by neglecting
wind on the roof.
- Roofs with Ridge
Line
Since we only use the smaller-negative or positive
windward coefficients as described in I.C.9.3 above, for all roofs with two panels separated by
a ridge line, the roof loading will always be in the direction of the wall
loading. Therefore, it will never be the critical case that roof loads are
neglected, so this note is not implemented for these roofs.
- Monoslope roofs
For monoslope roofs, it will always be the case
that shearline loading is maximized by neglecting windward roof loads.
Therefore, the program does generate windward loads on a monoslope roof panel,
and prints the following note under the Wind Shear Loads table in
the design results:
Windward load on the monoslope roof was not
generated, to comply with ASCE 7-02 Fig.6-6, Note 9.
- Low-rise Wind Loads
- Low-rise Load Cases
ASCE 7 02 Figure 6-10 replaces the concept of Case
A and Case B loads in ASCE-7 98 Figure 6-4, which are applied in 45-degree wind
direction ranges that are predominantly perpendicular to the parallel to the
ridge, respectively, with MWFRS directions that are longitudinal and transverse
with respect to the ridge. The values of the coefficients have changed such
that for the purposes of generating loads on the shearlines in a direction
orthogonal to the MWFRS direction, the coefficients on opposite sides of the
building now cancel. In ASCE-7 98, the co-efficients were different on either
side of the ridge, and either Case A loads, or Case B loads in either
direction, could be critical in the direction transverse to the ridge line.
As a result of the new zones and coefficients,
Shearwalls will no longer generate and compare two load cases for the direction
perpendicular to the ridge. Formerly it took the critical case of Case A and
Case B loads in that direction; now it uses the transverse coefficients only.
- Reference Corners
The program still generates and compares the loads
generated for the four reference corners for each load case.
- Load Case
Designation
In the loads list of the Loads Input view
the column "A/B" has been renamed "T/L" for Transverse/Longitudinal.
In this view, and in Load Case column of the Wind Shear Loads
table, the Shear Results table, and the Dragstrut and Holddown Forces
table of the results output, 'T' or 'L' is used for each load rather than A or
B. Throughout the log file report, Low rise case A or Low rise
case B are replaced with Low rise transverse and Low rise
longitudinal, respectively.
- Torsional Load Cases
and Rigid Diaphragm Analysis
- Torsional Load
Cases - Low Rise Note 5
The program does not implement the low-rise
torsional load cases given in Figure 6-10 Note 5. Users are directed to use the
All-heights method for torsional analysis.
- Rigid Diaphragm
Analysis
Because the torsional load cases are not
implemented for low-rise loading, the program no longer performs
rigid-diaphragm analysis for loads generated with the low-rise procedure.
- Rigid Diaphragm
Input and Display
When low-rise loads are present, the Rigid
Diaphragm selection is disabled in the Show menu and in the Loads
and Forces dialog. It is not possible to view Rigid Diaphragm forces
on the screen.
- Rigid Diaphragm
Output and Note
The entire section of the output report called Rigid
Diaphragm Analysis does not appear if any low-rise wind loads are present
in the structure. In its place there is a note saying:
Rigid diaphragm torsional analysis is not available
for ASCE 7 low-rise wind loading. If you wish to model torsional effects,
please use the ASCE 7 All-heights procedure to generate loads.
- Low-rise Zones
- Transverse zones 5
and 6
ASCE 7-02 has new end wall zones 5 and 6 that would
create loads perpendicular to the transverse design direction. These zones are
not implemented in our model as the resulting loads will cancel for the
purposes of shearline force generation.
- Longitudinal zones
2 and 3
In ASCE 7-02 roof and side walls are split into
leeward and windward halves with the same coefficients as the leeward and
windward sides of the ridge in the transverse case. These zones are not
implemented in our model as we are not considering forces orthogonal to the
MWFRS as described in I.D.1.a.
- Longitudinal End
zones
The new longitudinal roof end zones have not been
implemented, for the same reason as in I.D.3.b.
The longitudinal end wall end zone has been enlarged from a to 2a in width,
where a is as defined in Note 9.
- Zone numbering
The zones formerly called 5 and 6 on the end wall
for the longitudinal case are now 1 and 4 - this is reflected in the detailed
log file output. The other numbering changes are for loading in a direction
orthogonal to the MWFRS direction, so do not affect our model.
- Coefficient values
None of the changes to coefficient values affect
load cases and directions that we are considering, so the coefficients used are
the same as in ASCE 7-98. The interpretation of the model has changed, as
described in I.D.1.b, so there will be
changes in the resulting loads.
- Low-rise Hip Ends
The ASCE 7-98 implementation creates loads assumed
to come from the transverse direction on hip ends and the associated walls,
assuming that these ends are modelled the same as longitudinal side panels.
This is no longer done for ASCE 7-02, as they are orthogonal-to-MWFRS forces in
the longitudinal direction, and would cancel.
- Low-rise Note 6 -
Neglecting Net-negative Roof Loads
Figure 6-10 Note 6, formerly note 4b in ASCE 7-98,
specifies that the total horizontal shear in the structure should be the
greater of the two cases of including or ignoring roof loads. In effect, for
our simple model, it means that net-negative roof loading on the structure
should be ignored.
- Implementation for
ASCE 7-98
The program did an imperfect job of implementing
ASCE 7-98 Note 4b until version 2004, when it was removed. It did not consider
the effect of note 4a on the calculation, and it continued to display the loads
that it was ignoring when designing the structure.
- Implementation for
ASCE 7-02
Analysis has shown that it is very difficult to
create a building for which net-negative roof loads would be greater than the
loads on the walls, so that net-negative roof loads would be critical.
Therefore we decided to remove net-negative roof loads for all structures
.
- Method for Ignoring
Roof Loads
Shearwalls now detect roof angles under 22.45
degrees, and does not generate transverse loads for this situation.
This is the angle at which zone 2 coefficient used
on the windward panel equals the zone 3 coefficient used on the leeward panel,
therefore the windward and leeward loads cancel in our simple model. Note that
the loads created on the region governed by Note 8 cancel for any angle.
- Design Results Note
A design note has be added under the Wind Shear
Loads table in the output report indicating that the net-negative roof
loads were ignored in design for angles under 22.45.
- Hip ends
Loads on hip ends will also be ignored if they are
less than 22.45 degrees and would result in net-negative roof loading in the
longitudinal direction.
- Low-rise Note 7 -
Use of 0-degree Roof Slope
This note about the use of 0-degree roof angle,
which was Note 2 in ASCE 7-98 has been extended to refer to all longitudinal
loading. However, it does not apply to our new model, which does not design
include longitudinal roof loads as described in I.D.1.a.
- Low-rise Note 8 -
Windward Transverse Zones
- Applicability of
Note 8
Figure 6-10 Note 8, formerly note 4a in ASCE 7-98,
specifies that the windward roof panels are split into Zones 2 and 3 at the
lesser of half-width or 2.5 times the height of building from the eave.
Analysis shows that note 6 cancels note 8 for our simple model except for roof
angles between about 22.5 and 27.5 degrees. For angles less than the loads are
net-negative, thus neglected due to note 6; for angles greater, the coefficient
is not negative so Note 2 does not apply.
- Implementation of
Note 8
This note was implemented for ASCE 7-98, and was
retained for the new implementation for ASCE 7-02 with the correction noted in IIA5 regarding the sign of coefficients used for
windward hip ends.
- Designation of Note
8 Loads
In the loads list in Load Input View and in
the text results output, the loads are indicated by an (8) beside the Building
Element instead of a (4). In the log file, loads indicated as Load Case
A4 in the loads list are now referred to as T8 or L8 (for hip ends).
- Low-rise Load
Display
The following will occur when any generated
low-rise loads are present.
- Show Menu - MWFRS
Direction
The Show menu item formerly called Orientation
is now called MWFRS Direction to be consistent with terminology in
Figure 6-10 of the ASCE 7-02.
- Show Menu - Wind
Reference Corner
The Show menu item formerly called Load
Direction is now called Wind Reference Corner . The choices will be Northeast,
Southwest, etc. instead of selections of the type North to South,
East to West. This change is made in the Show menu only, not the Loads
and Forces settings, which are still Wind from southwest, etc.
- Show Menu - Wind
Load Case
The Wind Load Case (formerly Wind
Direction) item is now disabled for low-rise loads, as it is no longer
necessary to have two menu items to filter both the direction of load and Case
A and Case B loads.
- Loads displayed
The program no longer displays Case A and Case B
loads separately. Longitudinal and transverse loads for a particular Wind
Reference Corner appear on the screen simultaneously.
- Rigid Diaphragm
Loads and Forces
The Rigid Diaphragm selection is disabled
for low-rise loads in the Show menu and in he Loads and Forces
dialog. It is not possible to view Rigid Diaphragm forces on the screen
for low-rise loading.
- Seismic Loads
No changes for ASCE 7-02 as compared to ASCE 7-98
were necessary for Shearwalls. Refer to II.B1-3 for changes to the implementation of the Seismic
Design section 9.0 of ASCE 7 that became evident in our review of both versions
of the standard, but are not due to a change in the standard.
- Bug Fixes and Minor Changes
- Wind Load Generation and Distribution
- ASCE 7 Minimum
Design Wind Loading
Shearwalls did not implement the minimum value of
the design wind force of 10 psf multiplied by the area of the structure
projected on a vertical plane normal to wind direction as per ASCE 7-98 Section
6.1.4.1. Refer to I.B.1 for the new
implementation for ASCE 7-02.
- Net-negative
Low-rise Roof Loads
The wind roof loads generated for low-rise
buildings were not ignored by the design when their effect is contrary to the
shear force generated on the rest of the structure, as required by Fig.6-4,
Note 4b, p43 of ASCE 7-98. Refer to the new implementation of this feature for
ASCE 7 02 in I.C.10 above.
- ASCE 7 Rigid
Distribution for Low-rise Loading
For two of the four low-rise reference corners, the
vertical distribution of rigid shearline forces from upper stories was
repeated, resulting in double the shear force on lower floors. Only a small
number of multi-storey buildings meet low-rise restrictions, limiting the
impact of this problem.
- Low-rise Wind Loads
on Hip Roof End Wall
Roof panels and top-most walls on hip ends are
supposed to be treated as side panels and walls for the purposes of load
generation, as described in the on-line help and based on the Wood Frame
Construction Manual Table 2.5 A-B page 72-2, Note 4 . The program was applying
the side wall coefficients to all stories, not just the topmost one.
For hip roofs, the loads on the upper portion of
the hip ends generated according to the Low-rise Method in ASCE-7-98 figure 6.4
Note 4a (now ASCE 2 02 Note 8) led to positive wind loads despite the fact that
they have negative coefficients. This has been corrected
- Low-rise Height h
for Low Roof Angles
The calculation of roof height h was not using the
eave height as mean roof height for roof slopes less than 10 degrees, for
low-rise buildings as per ASCE 7 02 6.3 p. 25 and Figure 6-10 Note 7. It
impacted the following circumstances:
§
to
determine height-to-width ratio for low rise coefficients in Figure 6-10. This
is no longer an issue due to the use of -0.18 for all rations in ASCE 7-02.
§
to
determine the division point on the roof for the application of low rise Note 8
from ASCE 7 02 Figure 6-10. This increased the area over which Zone 3 loads
applied, conservatively increasing the total loading in the direction of the
MWFRS.
§
to
determine the height-to-width ratio for which low-rise buildings are allowed
according to ASCE-7 6.2, so that some small buildings that could have the
low-rise procedure were not being applied, conservative coefficients were
applied.
In all cases, the number of buildings affected is
small. The height in the log file for all-heights procedure was being
reported incorrectly for these buildings, but the correct h was being used for
the all-heights generation procedure.
- Seismic Load Generation
- Response
Modification Factor Adjustment
The program resets the response modification factor
R in both directions when it detects non-plywood sheathing on a floor according
to ASCE 7 9.5.2.2, instead of just the direction for which the sheathing was
detected. This was already the behavior for UBC.
- Limitations for ASCE
7 Seismic Design Categories
The program now prompts asks user if they wish to
continue load generation if the building falls outside of the limits for the
ASCE seismic design categories given in 9.5.2.2.4-5 and Table 9.5.2.2. In
particular, the warnings are for
§
Wood
shear walls in buildings greater than 65 ft in height for design categories D,
E and F.
§
Gypsum
shear walls in buildings up to 35 ft for design category D.
§
Gypsum
shear walls in any buildings for design categories E and F.
Note that the seismic design category is not
directly input by the user, but a consequence of the settings for Site Class,
S1, and SS in the Site Information dialog.
- Structural
Irregularities for Seismic Design
A red design note now appears under the Dragstrut
and Hold-down tables saying:
Shearwall does not check for either plan or
vertical structural irregularities.
These irregularities and their consequences for
seismic design are found in sections 9.5.2.3, 9.5.2.6, 9.5.2.6.4.2-3, 9.5.2.2,
and 9.5.2.7.1.
- Snow Weight in
Seismic Building Mass
Shearwalls now includes 20% of the input snow load
for the ASCE 7 seismic load generation, as per ASCE 7 9.5.3.8.1 and IBC 2003
1617.5.1, instead of 25% it was previoulsy showing. It now excludes the
snow load from consideration if it is less than 30 psf minimum specified in
these clauses and in UBC 1630.1.1.
Note that the on-line help still indicates that the
user must factor the snow load by 20% or 25%, and the program includes the full
input amount. This will be corrected for the next major version of the
software.
- Snow Mass on Flat
Roofs
Snow mass is not accounted for when building mass
is generated on a structure in which all roof blocks are set as a flat roof.
- Response
Modification Factor Message
The warning message about the need to reset the
seismic Response Modification Factor R because non-wood-sheathed walls exist
was appearing when all walls had only exterior sheathing, even though such
sheathing is made of wood. This has been corrected.
- Data Input
- Monoslope Roof
Creation
a. Via Roof Angle
It was not possible to change the roof angle field
in roof input view in order to create a 90-degree panel for a monoslope roof
situation.
b. Via Ridge Location
The program behavior when attempting to create a
monoslope roof via a movement ridge location was erratic and unpredictable. It
was only possible for some building configurations.
- Deleting
User-applied Forces
The program would crash any time a user-applied
shearline force was deleted. This has been corrected.
- Default Dead Load
Combination Factor
The default dead load reduction factor for new project
files were 1.0 rather than the 0.6 required in IBC 1605.3.1 and UBC 612.3.1. If
the user reset the original settings in the Design Settings, the correct factor
would be restored.
- Zero Wall Height for
Uneven Blocks
If the ceiling joist depth is changed while
entering the data in the Structure Input form for a block with fewer
stories than other blocks, the wall height on the storey above the lower
block's ceiling depth, on the taller block, was being set to zero. This has
been corrected.
- Dynamic Analysis
Input in the Site Information Dialog
When the Site Information dialog is
re-opened after the wind Design Standard was changed from All-heights
ASCE, the Dynamic Analysis checkbox remained checked and the Gust
factor edit box enabled. These controls are now unchecked and disabled for
the low-rise method and for UBC load generation.
- East-west Shearline
Forces in Load Input List
For East->west or West->east wind
shearline forces input directly, the load direction displayed in the load list
of load input view was the opposite of the input force. This did not occur for
north-south forces, and had no effect on load analysis or design.
- Program Operation
- Point Load on
Opening End
When a point load was added to a wall directly over
the start or end of an opening, the program was crashing.
- Program Crash on
Extend Walls
The Extend Walls feature was causing Shearwalls to
crash, for complex multi-block structures where adjoining blocks differ in
levels by 2 or more, particularly when the blocks are arranged in an L- or U-
shape.
- Wind Direction in
Elevation View
The Show ... Wind menu in elevation view disabled
one of the direction options so that you are unable to view loads and resulting
forces and design results in both directions. It was not possible to override
this behavior through the Loads and Forces settings.
- Show Menu Changes
a. Force Direction
When UBC-generated wind loads are present, or when
viewing seismic loads, the menu item currently called Orientation is now
called Force Direction. It has also changed for ASCE 7 generated loads
as described in I.C.5.a of this list.
b. Wind Direction
For all wind loads, the main menu item currently
called Load Direction is now called Wind Direction, as it does
not apply to seismic loading.
c. Wind Load Case
The menu item formerly called Wind Direction
is now Wind Load Case, with new choices as described in I.C.5.a of this list.
- Distribution Method
for User-applied Shearline Forces
The Distribution method of
user-applied shearline forces was not saved with the project file, so the Distribution
method for such a force was being reset to All Distribution Methods when
reopening the project file. This has been corrected
- Opening Files from
Previous Versions
Project files from previous major versions could
not be opened with versions 2004a or 2004b in the same session that a version
2004a/b file has been opened or saved.
- Status Bar Messages
The status bar was not displaying any message for
the Site Dialog or any of its controls, while for the Wall Input, Roof Input,
Generate Loads and Load Input views the messages were displayed only for some
of the input controls and were truncated in a few instances. New status bar
messages have been made for all controls in these views, and truncated status
bar messages have been abbreviated.
- Results Output
- Holddown Force
Heading in Output
Changed the heading for the Dragstrut and
Holddowns table from Holddown Force [lbs ] to Tensile Holddown
Force [lbs]
Design Office 2004 Service
Release 1
This Service Release consisted of a review of
all known problems and user issues with Shearwalls and a resolution to any of
these that were significant and/or simple to resolve. New features are
indicated by an asterisk (*).
Please note that this Service Release
includes changes from two versions of Shearwalls, 2004a and 2004b. Consult both
sections in the version history for bug fixes and features included with the
Service Release.
Version 2004b -
October 29, 2004
Bug Fixes and
Features
- Data Input and Program Operation
- Default Values Settings*
The operation of default settings for new files has
changed. If no file is open, all settings automatically are saved for new
files. If a new file file is opened only the Default Values settings are set to
Save for New Files. A note in the settings box indicates those Default Value
settings which have an effect on current file operation.
- Save as Default Operation*
In the Settings, the Save As Default
checkbox was by default not checked when a file was not open. Now, if a file is
not open, this is checked and disabled, and when a file is open, it is
unchecked and enabled.
- Zero Ceiling Depth*
The default ceiling depth in Structure Input View,
is now set to zero instead of the same value as joist depth.
- Exposure Dropdown Box Update
The Exposure drop-down box in Site
Information dialog is no longer blank after changing design code to UBC.
- Default Tributary Width
Manually entered area wind loads now have default
tributary width.
- Impact Resistant Checkbox
The Impact Resistant checkbox has been
restored to the Opening Input View.
- Update of Help Menu
After closing a project file, "Online Design
Code" in the Help Menu no longer changes from "NDS
online" to "CSA 086-01" or becomes disabled.
- View Area and Snap Increment Menu Item
View Area and Snap Increment selections in the View
data filter bar no longer cause Default Values settings to appear rather
than View Settings.
- Note when Resetting View Settings
When "Reset Original Settings" was
selected in the View Settings, a note about choice of unit systems no
longer appears.
- Width of Material Combo Box in Wall
Input View
The materials combo box, when not expanded, is not
wide enough to display the full text of some of the choices.
- Wind Direction Label
The second label saying "Wind from
Southwest" in the Loads and Forces Settings has been changed to "Wind
from Southeast".
- Data Visibility in Input Controls
Adjusted size and position of several controls in
Wall Input form and Site Dialog to allow data to be completely visible.
- Main Menu Key Shortcuts
Several main menu key shortcuts have been repaired.
"Alt+I" and "Ctrl+U" now work for Log File and for User
Manual, respectively; Extend Walls has been changed to Alt+E and Plan View to
Alt+P; and Ctrl-P prints.
- Load Magnitudes Format
The area load magnitude in the Load Input view now
has two-digit precision and all magnitudes show whole numbers as decimals.
- Underscores in Input Forms
Small underscores that appeared randomly in the
text labels of several input views have been removed.
- Inconsistent Capitalisation
Input fields throughout the program composed of two
or more words were inconsistently capitalised. The style is now sentence case
unless it is a title.
- Text Output
- Above and Below Escarpment Crest
Reversal
"Above" and "Below" crest of
escarpment are no longer reversed in the Site Information of the Design Report.
- Engineering Design
- Incomplete Design Material
Specification
For large, complicated structures with openings and
non-shearwalls, for some shearlines the Materials table contained "?"
for nail spacing or sheathing thickness.
- Perforated Wall Warning for UBC
The warning regarding no perforated walls for UBC
no longer appears when there are no perforated walls in the structure.
- ASCE-7 Gz for Windward Walls
The ASCE-7 minimum Gz factor for windward walls was
being modified slightly from 0.85 to e.g. 0.86.
- Seismic Load Generation
- Seismic Load Generation on Complicated
Structures
For large buildings containing many indentations
and protrusions, the generation of seismic loads caused the application to shut
down.
- Upper Level Wall Building Masses
The wall building mass created for the upper story
was based on the full height of the wall rather than half the height. However
the seismic loads generated from these masses were based on the correct height.
- Building Mass of Line of Non-shearwalls
The building mass of shearlines composed entirely
of non-shearwalls is now being included in generation of seismic building
masses.
- Building Mass of Intersecting Roof
Blocks
The building mass values shown in the Seismic
Information Table no longer includes the overhang on the intersecting portion
of two roof blocks.
- Wind Load Generation
- High Wind Loads on Roofs
For roofs less then 10 degrees using the ASCE
method, unrealistically high wind loads were being generated on the roofs on
the North-South direction.
- Wall Load Generation after Roof Move.
After a roof block was unattached from the rest of
the roof, the loads for the walls on that block were not being generated in the
same session.
- ASCE-7 Kz and Gz on Windward Walls
The ASCE-7 Kz and Gz factors were too small on
gable ends and too large on walls due to coarseness in the numerical
integration routine used to calculate them.
- Height z for ASCE-7 Gz and Kz
The height z reported in the logfile for the ASCE-7
Kz and Gz factors for windward walls is slightly low due to an error in the
numerical integration used to calculate them.
- ASCE-7 Kz and Gz on Gable End
The program was amplifying the ASCE-7 Kz and Gz
values slightly on the gable end by averaging over the height as if it was a
rectangular surface instead of a triangle.
- Width of ASCE-7 Zone 2 Low-rise Loads
When applying Note 4 from Figure 6-4, ASCE-7 98 the
program was mistakenly moving the dividing line in zone 2 by a small portion of
the eave width.
- Low-rise Tributary Width
When windward roofs are divided according to Note 4
from Figure 6-4, ASCE-7 98, , the area load tributary width shown in Load Input
View for each zone was the entire roof panel width instead of the width of the
divided zone.
- Low-Rise Zone 2 Roof Pressure
Coefficients
The program now divides all windward roofs with
negative GCpf coefficients into two areas with different coefficients for the
generation of wind loads acocrding to Figure 6-4, Note 4, ASCE-7 98. The loads
for the upper portion are indicated in the Loads List in Load View by (4).
Previously, it had been doing so only for roofs wider than 2.5 times eave
height, and was indicating these loads with (9).
- Wind Pressure on Gable Ends
A too low height z was being used to calculate the
ASCE-7 Kz and Gz factors on windward gable ends, resulting in lower than
expected wind pressures It was using the floor level floor height rather than
ceiling height for the calculation.
- Load Distribution, Accumulation
- Vertical Hold-down Components for
Perforated Walls
For perforated walls with openings, hold-down
forces derived from dead and uplift loads were not being generated.
- Rigid Distribution within Shearline*
For rigid diaphragm design, the shear force within
a shearline can now be be distributed to each wall according to the user input
relative rigidity times the length of the wall.
- Rigid Distribution to One Shearline in
each Direction
Program was attempting rigid distribution to one
shearline in each direction, even though torsional rigidity cannot be
calculated in this case. It now disallows such configurations.
- Display of Manually-entered Wall
Rigidities
Removed the e.g "( Wind Design )" from
the Wall Rigidities input field for manually entered rigidities, and now
apply the input rigidity to both wind and seismic design.
- Vertical Distribution of Forces
Factored with Rho
The rho factor was being re-applied to seismic
shearline forces when it was distributed from an upper level to the level
below.
- Vertical Distribution of Load
Combination Factor
When shearlines on upper stories did not have any
walls directly bellow, in the flexible distribution method the load combination
factor was being re-applied as the force was distributed from an upper level to
the level below.
- Building Model
- Merging Walls - Effect on Roof Joining
Merging walls on two abutting blocks caused the
blocks to abut rather than overlap, and the roofs not to join or to be able to
be joined manually.
- Wall Extension for Multiple Uneven
Story Blocks
When three or more adjacent blocks were defined
such that the middle block had fewer levels than the outside blocks, the
extension of walls to upper floors caused the program to hang.
- Interior Walls Protrude outside
Building
It is no longer possible to move exterior walls
such that interior walls extend outside of the building.
- Shutdown on Extend Walls Upwards
When exterior walls connected to interior walls
were moved, the program could shut down when walls were extended upwards.
- Roofs on Three Block Multilevel
Buildings
Roof creation no longer fails for center block in
three adjacent block multi-level building with different numbers of levels.
- Plan View Graphics
- Hold-down Symbols in Plan View
Symbols for adjacent hold-downs on large buildings
no longer obscure the display of force values.
- Elevation View Graphics
- Elevation View Layout*
Numerous improvements were made to the appearance
and readability of the Elevation View display and printout, such that the
elements have appropriate sizes and do not obscure one another.
- Update of Forces in Elevation View
Forces on the walls are now shown in Elevation View
after selecting the Generate Loads action. Previously, the Load Input View had
to be selected before going to Elevation View.
- Installation
- Network Installation of Shearwalls
Shearwalls installed on a server could not be
accessed from a user workstation if the OCX file for the Enhanced Output
Reports had not been setup on that workstation. Procedures described in this
file are now in place to allow this.
- Shearwalls Example Files
Shearwalls example files in installation could not
be opened. These files were removed from the installation.
Version 2004a - March 8, 2004
This version was supplied to users via e-mail
upon request. It was not a general release.
Bug Fixes and Features
- Engineering Design
- Ignore Height-to-width Ratio in Design*
A checkbox was created in the design settings page,
so that the user can choose to not to apply the height-to-width ratio
limitations. This allows modeling of proprietary shear elements.
- Load Distribution, Accumulation
- Hold-downs at Openings on Perforated
Walls.
Hold-downs were being created at openings for
perforated walls, which should have hold-downs only at the ends.
- Elevation View Graphics
- Design Shear on Non-Shearwalls in
Elevation View
The design shear was displayed at the base of
non-shearwalls in the elevation view if the non shearwall was once a shearwall,
and persisted after another design was run.
- Shearline Forces on a Non-Shearwall in
Elevation View
After changing the wall type in an entire shearline
from shearwalls to non-shearwalls, the shearline forces were still being
displayed in elevation view after the next design.
Version
2004 - December 2003 - Design Office 2004
- Design Codes
- Remove SBC and NBC
- Remove SBC and NBC design code choices
from the design settings box.
- Remove SBC and NBC default load
combination factor, default wind stress increase factor, default
shearwall height to width ratio, and default sheathing combination rule
- No other provisions were added for
these
- Add AF&PA option
- Add "Use AF&&PA AWC 2001
Wind and Seismic Supplement and/or Wood Frame Construction Manual"
design setting
- Use provisions from American Forest
and Paper Association (AF&PA) American Wood Council (AWC) Wood Frame
Construction Manual for One- and Two-Family Dwellings (WFCM), and
ASD/LFRD 2001 Edition Supplement Special Design Provisions for Wind and
Seismic (Supplement)
- Where the provisions differ, use
provisions from the Supplement unless it does not exist in the
supplement and it does in the WFCM, or there is some other reason to use
the WFCM provisions that is explained
- Add design provisions
- Implement comprehensive design
provisions instead of a few design setting defaults, as explained in the
following sections
- Design code descriptions in user
interface
- Place design code year in text output,
site dialog, and settings dialog
- Shearwall Materials
- Sheathing materials
- Remove 5/8" lumber sheathing
thickness
- Add double diagonal lumber sheathing
as per IBC 2306.4.2 p467, UBC 2315.3.1, 2 p2-279, and AF&PA
Supplement Table 4.3C p27
- Add vertical lumber sheathing for
AF&PA option as per Supplement Table 4.3C p27
- Do not include 1/2" regular
fiberboard for IBC, as per Table 2308.9.3(4) p482
- Change gypsum and lath thickness from
3/8" to 7/8"
- Add 5/8" x 4' gypsum sheathing
for IBC as per Table 2306.4.5p471 and for the AF&PA option as per
Table 4.3B p26
- Wall stud materials
- Add grade input to wall input view for
MSR/MEL studs
- Change MSR/MEL specific gravities to
be dependent on grade as per NDS Supplement
- Stud spacing limitations
- Allow 24" stud spacing for 5/16
plywood, with the wind C&C bending capacity being zero. D
- Restrict structural fibreboard
sheathing to 16" maximum spacing as per IBC Table 2304.6 p449, UBC
2315.6 p2-280, and WFCM Table 3A p273 and Supplement 4.3.7.3d p23.
- Restrict wire lath and plaster and
gypsum lath materials to 16" maximum spacing as per IBC Table
2304.6 p449, UBC 2513.3 p2-381 and AF&PA supplement Table 4.3B p26
- Restrict all gypsum sheathing to
16" max spacing except for 1/2 x 4' blocked for IBC and AF&PA,
according to UBC Table 2513.3 p2-381, IBC Table 2306.4.5p471 and
AF&PA supplement Table 4.3B p26
- Restrict UBC stud spacing for gypsum
wallboard to 16' as per 2513.3 p2-381
- For IBC and AF&PA, restrict stud
spacing for blocked walls to 16" according to the aforementioned
references.
- Fasteners
- Allow both common nails and galvanized
siding or casing nails for plywood siding
- Allow 6d nails for 1/2"
structural fiberboard for UBC as per Table 23-11-B-1 p2-282 and IBC as
per Table 2304.9.1 p455
- Change specification of gypsum and
lath nail to "13 ga, 1-1/8"" from "13ga, 16ga"
- Change specification of wire lath and
plaster and gypsum sheathing screw to "11 ga, 1.5" from
"11ga, 16ga"
- Remove 8d,10d, and 16d gypsum
wallboard nails for all materials. Remove 6d nails from 1/2"
materials. Only one size of nail is specified for gypsum wallboard
choice.
- Fastener spacing
- 2', 3" and 4" edge spacing
for fiberboard for AF&PA option as per Table 4.3A p25
- Restrict intermediate spacing for
3/8" and 7/16" plywood with 24" stud spacing to 6"
maximum from 12", according to IBC T able 2306.4.1 p469 Note b, UBC
Table 23-II-I-1 p288 note 1, and the AF&PA supplement
4.3.7.1b.
- Change intermediate spacing for wire
lath and plaster from 10" to 6"
- Change intermediate spacing for Gypsum
lath from 10" to 5"
- Change field nail spacing for gypsum
wallboard from 10" to either 4 or 7", according to what is
selected as the edge spacing.
- Allow user to choose between 7"
base and 9" face nail , for display purposes only
- The above gypsum provisions are from
IBC Table 2306.4.5p471, UBC Table 25-I p2-382, AF&PA Supplement
Table 4.3B p26.
- Allowable Shear Strength Provisions
- Shear strength values
- Update low specific gravity plywood
shear strength values for the AF&PA option from WFCM 1995 to WFCM
2001 values in Table 3C, p277
- Implement correct shear strength
values for plywood siding based upon choice of fastener type as per WFCM
2001 Table 3C Note 6
- Implement AF&PA structural
fiberboard values from Supplement table 4.3A p25 for 2", 3"
and 4" edge spacing, but retain regular value from WFCM.
- Change structural 1/2" fiberboard
value from 175 psf to 125 psf for IBC according to Table 2308.9.3(4)
p482
- Implement strength of 600 psf for
double diagonal lumber sheathing for all design codes, and implement
strength of 45 psf for vertical lumber sheathing for AF&PA,
according to Supplement T4.3C p27, UBC 2319.1-2 p2-294, and IBC 2306.3.4
p464 and 2306.3.5 p467 .
- Implement strength of 200 psf for
5/8" x 4' gypsum sheathing for IBC and AF&PA according to
Supplement T4.3C p27 and IBC T2306.4.5p471.
- Implement the following new gypsum
sheathing strengths
- 1/2" board,
4" edge nail spacing, unblocked, 24" stud spacing - 24"
- 110 psf
- 1/2" board,
7" edge nail spacing, unblocked, 24" stud spacing - 24"
- 75 psf
- 5/8" board,
4" edge nail spacing, unblocked, 24" stud spacing - 24"
- 145 psf
- 5/8" board,
7" edge nail spacing, unblocked, 24" stud spacing - 24"
- 115 psf
- 5/8" board,
7" edge nail spacing, blocked, 16" stud spacing - 24" -
145 psf
- The last of these
is for all three design code options, according to IBC Table
2306.4.5p471, WFCM Table 3C p278, Supplement T4.3C p27 , and UBC Table
25-I p2-382. The first four do not apply to UBC.
- Bug fix - UBC 50%
- Specific gravity adjustment
- Implement UBC specific gravity factors
for plywood panels and plywood siding from Table 23-11-I-1 p288, Note 1,
and for lumber sheathing from 2319.1, 2 p2-294
- Implement IBC equation for plywood
panels and plywood siding from Table 2306.4.1 p 469 Note a
- Implement IBC factors for fiberboard
from Table 2308.9.3(4) p482, Note f.
- Implement equation from AF&PA
supplement for fiberboard from Table 4.3A p25.
- Change high-range specific gravity
cutoff point from .49 to .50 for AF&PA and IBC
- Bug fix - The erroneous application of
the IBC specific gravity reduction factor was causing the shear capacity
of Structural 1 sheathing to be less than expected.
- Wind increase factor
- Implement 1.4 wind increase factor for
fiberboard and lumber sheathing for AF&PA option according to Table
4.3A p25
- Rename to "Allowable shear stress
adjustment" from " Wind Capacity Increase - Shear"
- Combination of sheathing capacities
- Implement combination of sheathing
capacities according to design code rules, wind or seismic design, and
material type.
- For IBC, use rules in 2305.3.8 p463
- For UBC, use rules in 2319.3 p2-294,
2513.1.2 p2-381, and 2513.1 p2-381
- For AF&PA, use Wind and Seismic
Supplement 4.3.3.2 p19-20
- Bug fix - When exterior and interior
surfaces of shearwalls had different materials the shear capacity of the
interior wall was omitted.
- Local building code reductions
- Add design setting input fields for
local wind and seismic capacity reductions
- Save to project file and as a default
setting
- Factor plywood and lumber sheathing
only, not gypsum and plywood
- The values are limited to between 0
and 1
- Seismic height/width shear
reduction
- Implement factor for plywood h/w
ratios between 2 and 3.5
- Implement for AF&PA option
according to Wind and seismic supplement Table 4.3.4 p21 Note 1
- Implement for IBC according to Table
2305.3.3 p460 Note a
- Allow user option of reduced strength
or more restrictive lengths
- Report factor in design results
tables
- Seismic shear reduction for
gypsum
- Implement 50% shear reduction for UBC
gypsum materials in zones 2,3,and 4 as per Table 25I p2-382. It was in previous
versions of Shearwalls but not the 2002 version.
- Do not implement 50% shear reduction
for WFCM in Design category D as per Table 3C p278 Note 2, as it is not
in the Supplement and does not accord with strict ASCE-7 R value of
2.0.
- Design notes
- The program issues a note about
framing details if the capacity is greater than 350 psf, according to
Table 2306.4.5 Note a p471 , UBC Table 23-II-I-1p2-288 note 3, and
AF&PA Supplement 4.3.7.1 p22-23 c (3).
- Shearwall and shearline limitations
- Height-to-width ratio
- Remove height-to-width option from
design settings, and calculate automatically instead
- Implement according to UBC Table
23-II-G, IBC Table 2305.3.3 p460, and AF&PA according to Wind and
Seismic Supplement Table 4.3.4 p21
- Implement different ratios for wind or
seismic design, using most restrictive case of wind and seismic design
if both types of loads exist
- Implement different rations for each
and material type
- Implement different ratio for UBC zone
4 for plywood and lumber sheathing according to Notes 1 and 2
- Implement different ratio for blocked
vs unblocked plywood as per IBC note b, AF&PA note 2, and UBC
table.
- Implement different ratio for lumber
sheathing orientations, using 3.5 for double diagonal for all design
codes.
- Use most restrictive case of materials
on either side of shearwall
- Consider "ignore
non-plywood" option in determining ratios
- New setting to allow height-to-width
ratio of 3.5 for IBC and AF&PA seismic design rather than 2.0 ( and
apply factor)
- Height restriction
- Remove warning for shearwalls outside
of 8 foot to 10 foot height limits
- This was from WFCM 1995 prescriptive
design
- Shearline offsets
- Changed the shearline offset for NDS
from 2 or 4 feet to 6 inches.
- Change elevation 2 or 4 joist depths
to 1/2 joist depth
- Shearline offsets no longer dependent
on design codes.
- Seismic design category limitations for
materials
- Implement warning in Design Results if
user designs with a material not permitted in the seismic design
category used to generate loads.
- The limitation to categories A,B, and
C for fibreboard come from IBC 2306.4.4 p470, and AF&PA Supplement
4.3.7.3 p23
- The limitation to categories A,B, C,
and D for diagonal lumber sheathing come from IBC 2305.3.1 p460, and
AF&PA Supplement 4.3.7.4-8 p23. The AF&PA also restricts
straight lumber sheathing to A, B, and C.
- The limitation to categories A,B, and
C for IBC and for gypsum materials come from IBC 2305.3.1 p460, and to
A,b,C, and D in AF&PA Supplement 4.3.7.3 p23. However, we were
informed that the IBC clause was in error and zone D should be included
for IBC as well.
- Seismic Design - ignore non-plywood
materials
- Add design setting checkbox for
"ignore non-plywood when combined with plywood" for seismic
design.
- Save to project file and as a default
setting
- When activated, do not include
non-plywood materials when combining sheathing capacities with plywood
- Take into account when determining
response modification R factor
- Take into account when determining
maximum height-to-width ratios.
- C&C design provisions
- Bending resistance
- With the exceptions noted below,
update all WFCM 95 plywood, fiberboard, and lumber sheathing bending
strength values to WFCM 2001 Table 3A p273 for all design codes
- Retain values for 5/16 plywood from
1995 WFCM because they are not in the 2001 version.
- For 12" stud spacing,
perpendicular to supports, 19/32", 23/32" plywood sheathing
thickness. use values from AF&PA supplement Table 3.2A p9 as they
are markedly different because the shear stress checked and is
critical.
- Change value of load duration factor
increase from 1.5 to 1.6 as per Table 3A note 1.
- Factors for nail withdrawal
- Allow user to specify temperature and
fabrication and in-service moisture conditions in the Design Settings
- Save these values to project file and
as default settings
- Apply the CM factor for moisture from
NDS 2001 10.3.3 p59, to nail withdrawal resistance
- Apply the CT factor for temperature
from NDS Table 10.3.4 p59 to nail withdrawal resistance
- Load duration factors
- Amalgamate bending and nail withdrawal
load duration factor into one input control
- Rename to "C&C load duration
for nails and sheathing" from "Wind Capacity Increase -
C&C Panels" and "Wind Capacity Increase - Withdrawal"
- Perforated Shearwalls
- Rename
- Changed Type II to Perforated and Type
I to Segmented
- Applicable Design Codes
- Allow for AF&PA and IBC only,
disallow for UBC
- Holddown calculations
- Implement equation from IBC Equation
23-3, 2305.3.7.2.4, p462; WFCM ( Table 3B Method 2 p 275) and AF&PA
Supplement ( Eqn. 4.3-6, 4.3.6.4 p22 )
- Divide hold-down force as currently
calculated by Co perforation factor at ends of perforated walls
- Maximum capacity
- Program implements maximum shear
capacity for perforated shearwalls from IBC 2305.3.7.2 -1. p462 and
Table 3B Method 2 i.
- When materials are entered that have a
capacity greater than this capacity, the materials' capacity is reset to
the amount.
- For IBC, the maximum capacity of 490
plf applies toe each side of the shearwall separately, before the 1.4
wind increase factor is applied.
- For WFCM, the limit of 800 plf applies
to the combined capacity of both sides of the shearwall after it has
been factored by 1.4.
- The provisions from the AF&PA
supplement ( 4.3.5.2 Note a . 1000 plf ASD) have not been applied
- Shearwall Design routine
- Bug fixes
- When designing for shear wall
unknowns, the design process stopped at the first set of values even if
these caused a design failure for that wall.
- Walls with unknown stud spacings were
not being designed for seismic design cases. This resulted in materials
table listing unknown data and seismic shear results with incorrect data
or missing entirely
- Multiple wall groups were being
generated with identical materials when walls had only exterior
sheathing.
- The materials table listed ? and -1,
for unknowns and defined fastener sizes and stud spacing, when designing
for C&C wind loads.
- If the user selected strongest or
twice weakest as the sheathing rule, the design loop would approximately
double the design strength when determining whether a design passed.
Consequently, failed designs would show up in the output report as
passed.
- Redundancy/ Reliability factor
- Design Codes implemented
- Implement Section 9.5.2.4, pp 128-9 of
ASCE-7 for IBC and AF&PA option and Section 1630.1.1, p 2-13 for the
UBC. The procedures are slightly different.
- Restrict to UBC zones 3 and 4
- Restrict to ASCE-7 Seismic Design
Categories D, E, and F.
- Redundancy Calculations
- For ASCE-7 determine a maximum r and
floor area A for each floor to determine a ? for that floor, then takes
the maximum ? for all floors.
- For UBC determine the greatest r for
all floors at or less than 2/3 building height, and uses it and the base
floor area A determine the ? for the structure.
- Implement average floor area for upper
floors not same size as base floor for UBC.
- Limit the value to between 1.0 and
1.5.
- Design Procedure
- A separate calculation is performed of
each direction of earthquake force, and for each of rigid and flexible
distribution.
- Applies redundancy factor to shearwall
forces.
- Perform one iteration of design on
entire structure to determine redundancy factor and a second to design
shearwalls
- Input and Output
- Remove input of redundancy factor in
Site dialog
- Display redundancy loads unfactored by
? and forces factored by ?.
- Displays a line on the screen in which
is indicates the ? value in the earthquake load combination.
- Outputs A, and ? and r in each
direction in tables for rigid seismic design data and flexible seismic
design data.
- Vertical load
- Analysis and Design
- Calculate vertical load for seismic
design as per ASCE-7 9.5.2.7
- Apply when calculating the combined
hold-down force
- Display
- Display on a line screen as part of
seismic load combination information
- Display in results output under the
Seismic Information table.
- Response modification factor R
- Input and output
- Allow input in both force directions
- Output in design results in both
directions
- Implement design code values
- Corrected the default R for IBC from 6
to 6.5 according to Table 1617.6.2 p334, and implemented value of other
materials - 2.0,
- Implement the UBC 4.5 factor for
buildings 4 stories or more according to Table 16-N p 2-32 and the other
materials value of 4.5
- AF&PA 2001 WFCM/Supplement uses
ASCE-7 98 - Wood panels - 6, Other materials - 2.0, from Table 9.5.3.3
p124
- Load generation
- Use separate R in each force
generation
- Detect non-plywood materials in each
direction or more than 4 stories for UBC and prompt user before load
generation,
- Allow user to agree to change R value
to 4.5 UBC and IBC or ASCE-7 2.0 according to above mentioned tables
- Take into account the "ignore
non-plywood" option when determining whether there are such
materials on building
- Building masses
- Snow loads
- Allow user to enter the snow load as a
self-weight,
- Generate building mass as if snow
extends over the entire projected area of the roof minus the overhangs,
as if it were a flat-roof load.
- Implement default value for ASCE-7 of
20% of 30 psf = 6 psf (, ASCE-7 98 9.5.3.2)
- Implement default value for UBC of 25%
of 30 psf = 7.5 psf UBC (1630.1.1)
- Include in seismic load generation
calculations
- Display as "snow" in load
list and design results
- Ceiling loads
- Indented under roof masses to make it
clear that it is only the upper storey roof
- Bug fixes
- Program would create point building
masses with magnitudes of zero, plan view erroneously drew these masses
instead of omitting them from the view.
- Fix crash for diaphragm generation on
very large convoluted structures
- Period T
- Input and output
- Allow input of separate T in each
force directions
- Output T in design results in both
directions
- Analysis and Design
- Update both T's with approximate Ta
- Use separate T in each force
generation
- Bug fixes
- Calculation of fundamental period Tmax
generated unexpected values do to incorrect table lookup of Cu
- Output
- Log file output
- Cleaned up and reorganised symbols and
equations
- Equations include references in design
codes and standards
- Site information cleaned up
- All intermediate results put in tables
- Units and precision fixed.
- Seismic results table
- New seismic information table in
output
- Site dialog
- Occupancy
- Remove designation of ASCE-7
occupancy, as it is now the same as IBC and SBC and NBC were removed
- Change IBC occupancy categories
- Add full description of occupancies in
dropdown
- Bug fixes
- The Building Site dialog box had to be
invoked and the OK button clicked to set the defaults values to generate
seismic loads. If this step was ignored, no loads were generated.
- Site coefficients Fa and Fv for ASCE-7
, Ca and Cv for UBC not being saved to project file
- ASCE-7 Low-rise method
- Windward corners
- Implement loads from each windward
corner as separate cases, so that the there is one end zone instead of
two
- Display each windward corner case
independently on the screen, and choose among them using settings and
show menus
- Show arrow on screen showing the
windward corner being viewed.
- Distribute loads to shearlines
independently for each windward corner case for both rigid and flexible
method
- Design shearwalls using worst case
forces due to loads from all windward corners and show critical corner
in shear results table
- Show windward corner in shear results
output and drag strut and hold-downs table
- Show windward corner in load list in
Load Input view and in the Design results list of loads
- Show windward corner in log file
output
- Wind Cases
- Implement Case A (generally
perpendicular to ridge) and Case B (generally parallel to ridge)
loads.
- Display Case A and Case B loads
independently on the screen.
- Allow user to choose east-West or
North-South loads in design settings or show menu, and convert
internally to Case A or Case B.
- Distribute loads to shearlines
independently for each load case for both rigid and flexible
method
- Design shearwalls using worst case
forces due to Case A or Case B loads
- Show load case in Load Input view and
in the Design results list of loads
- Show load case in shear results output
and drag strut and hold-downs table
- Tilt arrow on screen to show load case
being viewed.
- Show wind case in log file output
- Building restrictions
- Disallow low-rise load generation
loads on multi-block structures until design methods are approved by the
code authorities. Issue message to this effect.
- Disallow low rise wind loads for
eccentric ridge line and issue message.
- Disallow low-rise wind loads for hip
ends with different slopes and issue message
- Disallow wind loads for ASCE-7 6.2
restriction that mean roof height is less than 60 ft and issue
message.
- Disallow wind loads for ASCE-7 6.2
restriction that height be less than least horizontal dimension and
issue message.
- Disallow loads for closed structures
as per ASCE-7 6.2 and issue message
- Issue warning message if building has
unevenly sized stories.
- Hip roof design
- Apply loads to hip roof ends as if
they were side panels, according to WFCM Table 2.5 A-B page 72-2, Note
4.
- Issue warning to the user in this
circumstance
- Windward roof loads - Note 4
- Implement ASCE-7 Figure 6-4 Note 4a -
for Case A loading and negative windward roof loads, use the leeward
load coefficient for the specified are of roof
- Create one or more special loads
depending on the roof structure, referred to as Note 4a loads in the
load list.
- Implement for hip ends
- Topographic Factor
- Input
- Add hill shape, height, length,
distance to crest inputs and upwind/downwind checkbox to site dialog
- Activate rest of controls based on
existence of hill; activate checkbox for escarpments only
- Design
- Calculate Kzt based upon ASCE-7
6.5.7.2 p 30 and figure 6.4 p48
- Implement H/L > 2 restriction from
6.5.7.1(4) p 29
- Implement height restrictions based on
exposure from 6.5.7.1(5) p29
- Integrate Kzt over surface separately
from other factors, resulting in a different avg. z for Kzt
- Output
- Output input data to Building Site
table in Design Results.
- Report Kzt and z for Kzt in log file
output for each building surface.
- Overlapping Building Elements
- Input
- Add setting in Load Generation options
for "Exclude roof portion covered by other roof
- Load Generation
- If checked, discount the redundant
loads that are created when one building roof surface is in front of
another.
- divide the roof panels into triangular
and trapezoidal segments, increasing the number of wind loads on the
structure.
- Take into account end zones and Note 4
loads when splitting up roof.
- Walls and Roofs
- If a roof frames into a wall on the
same storey of a taller block, then the covered portion of the wall is
excluded,
- in some cases the portion of a roof
covered by a wall is excluded.
- Bug fixes
- Problems with definition of end zone on
convoluted structures fixed
- Problems with wind loads on trapezoidal
roof panels fixed
- Shearline forces
- Negative shearline forces
- Change made to plan view and elevation
view
- For shear forces from negative wind
loads, revert the direction of the arrows and display the magnitude as
positive.
- Load combinations
- Input
- Reorganise load combination factors in
design settings
- Refer to them as load combination
factors to make them understandable
- Drop terminology Dead Load Reduction
Factor, Seismic Load Reduction Factor
- Display
- Display unfactored wind loads (
previously loads were factored)
- Display factored shearline forces
- Display factored combined hold-down
forces
- Show line at bottom plan view
indicating load combination being used
- Print note under loads table saying
that they are unfactored loads and indicating the amount they will be
factored.
- Shearline force distribution
- Bug fixes
- Calculation for torsional shear force,
for rigid distribution method, was omitting the negative direct loads
- In the unlikely circumstance that
negative wind loads are critical, was creating hold-down forces in wrong
direction and not designing walls correctly
- Vertical Load/Force Distribution
- Bug fixes
- The partitioning of line loads over
openings and segments were incorrect when wind uplift loads were present
and seismic building masses were also present.
- In Hold-downs and drag strut table,
the position of the hold-downs was being displayed as Vertical Element
rather than the appropriate window or wall end
- Blocks
- Bug fixes
- When certain configurations of three
or more blocks were created such that they were diagonally abutting and
Roof action selected Shearwalls would freeze.
- When three blocks, with identical Y
coordinates, were created, with the center block containing more levels
than the outside blocks, the roof on the centre block was
corrupted.
- When multiple blocks were created, and
a wall from a block, which had blocks on either side, was first
segmented and the new wall segment was moved, the blocks became disjoint
and a gap appeared.
- When two blocks with different levels
were created, and their bordering walls were manipulated such that the
higher block had a smaller footprint at the interface, upon extending
the walls to upper levels, walls were created that were longer than they
should have been.
- When three blocks were defined
sequentially, with the outer blocks set to have 2 levels and the middle
block set to have one level, upon extending the walls to upper levels
upper level walls were generated for the middle block.
- Roofs
- Bug fixes and improved operation
- The slope of certain roof panels which
joined other panels slopes were being set incorrectly causing erroneous
looking roof diagrams and affected wind load calculations involving roof
slopes.
- When two adjacent blocks were
positioned such that they both had an outside wall at the same X or Y
coordinate the roofs did not join, and it was impossible to make them
joins
- When the roof configuration such as
roof type, slope, location and/or elevation was modified the change was
not reflected in adjacent block's roofs which were joined before the
change.
- Walls
- Bug fixes
- under certain circumstances the
automatic deletion of walls, resulting from the movement of wall
segments, would cause the application to crash.
- Loads
- Load list
- Remove name from load list
- Add Block, force direction, low rise
load case, face and building element
- Sort by each of these criteria using
title bar.
- Bug fixes
- Problems with scaling of loads fixed,
so that a more consistent size of arrows appears
- Output and display
- Settings
- New setting to allow automatic
switching to landscape mode for font sizes greater than 10 in results
view
- Removed setting to fit results view
into one page
- Unit system set to imperial only
- New options display setting checkbox
to always show roof in plan view
- Removed checkboxes for Shearwall
Segments table, and openings with this table
- Bug fixes and improved operation
- Load generation details in log file
were deleted when project file is closed. For new sessions, existing
loads had to be deleted and new loads generated.
- When printing the results view
contents the document header and page number was printed only for the
first page.
- Show menu changes
- Seismic and wind
- Seismic and wind are now first-level
choices without submenus
- Loads
- Move diaphragms from Seismic submenu
to Loads submenu
- Load Direction
- Implement 4 wind load directions
corresponding to windward corners of low rise method
- For all heights method, offers choice
of every combination of wind directions
- Disabled for seismic
- Wind direction
- Implements low rise Case A and Case B
loading, depending on ridge direction
- Has no effect for all-heights method
- Disabled for seismic
- Critical forces in plan view
- Add a menu item named Critical forces
at the top of the Show menu submenu Load Direction
- Disable Load Direction and Wind
Direction if Seismic is selected
- Menu item is enabled only for the Low
Rise case, only if there exist low rise loads on the structure
- if checked disable all Load Direction
and all Wind Direction submenu items on the Show menu, disable Shear
Loads, do not show shear loads on screen, show critical shearline and
hold-down forces all of the wind cases.
- if unchecked, enable all Load
Direction and all Wind Direction submenu items on the Show menu, enable
Shear Loads, show shear loads on screen if they were shown before.
- Elevation View changes
- For Wind Low Rise case always identify
and enable the wind direction which represents the critical case and
disable the other wind direction on the Wind submenu of the Show menu.
- Remove the directions from the Seismic
direction cases West to East South to North and East to West, North to
South as these are meaningless
- Make Seismic as a checked/unchecked
Show menu item.
- If user has selected Seismic loads in
PlanView, then switches to ElevationView, then Selects Wind Loads, upon
returning to PlanView the Critical forces will be shown.
- Design Results
- New architecture
- full page, page width or zoom
- Navigation between pages with control
at top of view
- Navigation directly to table with menu
in toolbar
- Keyboard and mouse navigation
- Organisation of data
- The output is now reorganized into
four major sections: Project Information, Structural Data, Loads, and
Design Results
- Show button menu reorganized and table
menu organized to reflect organization of the results tables
- The display of all loads tables can be
toggled on or off with single menu selection
- Pagination, page breaks after tables,
table title and continued on each page
- Automatically switches between
landscape and portrait to fit tables option
- No longer shows titles if tables or
sections are not shown.
- Formatting
- Bold, Arial font headings and titles,
fixed pitch table data, notes in italics
- Tables have distinct headings and
columns
- Borders around tables
- Blank lines inserted in tables with
subtitle to delineate shearline or level
- File Output
- User can choose to save output in Rich
text file (.rtf) format or portable document format (.pdf).
- Printing
- Able to print individual pages or page
ranges.
- New and Removed Tables
- Remove Shearwall Segments table
- All but the shear force and capacity
information now resides in the Shearline, Wall and Opening Dimensions
table.
- The shear force and capacity are now
listed in the Shear Results tables.
- Add Seismic Information table i
- Building mass and storey shear moved
here from storey information table
- Show storey shear in both force
directions
- Add floor area, Rmax in both
directions and reliability/redundancy factor in both directions
- Changes to existing tables
- Company and Project Information
- Now listed only if company or project
information is entered in settings dialog
- Design Settings
- Now organised into a table
- Maximum height-to-width ratio is
output for each material
- Include wind generation and seismic
generation standards
- remove sheathing combination
- Add new settings and factors
- Site Information
- Now organised into a table
- Include T and R in both
directions
- Remove redundancy factor
- Story Information
- The building mass and story shear are
no longer presented here. They have been moved to the new Seismic
Information table
- Block and Roof Information
- Location and Extent are now shown for
both directions.
- Ridge Location and Ridge Elevation now
refer to the absolute values.
- Relative values also output Ridge
Offset and Ridge Height
- The roof panel masses are no longer
listed.
- Shearline, Wall and Opening
Dimensions
- Add openings, height and length of
shearlines and openings, and shearwall type
- Add descriptions of line, level, and
wall for clarity
- Add otherwise bank title line for
levels and shearlines
- Loads and Forces - General
- Loads displayed either separately or
combined in wind shear loads table via new Loads submenu Wind Shear
Loads
- Loads now sorted much better by Block,
Load Case, Direction, Location etc,
- Wind Shear Loads
- The Block and Element columns replace
the Name field.
- Low rise reference corner and wind
case are listed in the Load Case column.
- Surface direction (Surf Dir) replaces
the Wind Direction column.
- There is a new wind direction column
(Wnd Dir) which lists the actual wind direction.
- The magnitude column is split into
Magnitude Start and End
- The tributary width column is renamed
Trib Ht which better represents the value
- Wind C&C Loads
- Name column renamed as Block
- Dead Loads and Uplift Loads
- Name column lists only the name and
not the origin of the load.
- The magnitude column is split to
Magnitude Start and End columns
- Building Masses
- Added Force Dir and Block
columns.
- Renamed Name column as Building
Element.
- Split magnitude column to Magnitude
Start and End
- Seismic Loads
- Added Force Dir column.
- Split magnitude column to Magnitude
Start and End.
- Removed Name and Building Face
columns.
- Level column is now in the table
heading
- Wind and Seismic Forces
- Name column deleted
- Shear Results
- Amalgamated shear results by segment
and shear results by shearline
- Added rows for walls, and otherwise
bank title line for levels and shearlines
- Renamed Cumulative Shear Force
grouping as Shear Force.
- Renamed Shear Capacity grouping as
Allowable Shear.
- Added load case and reference corner
for low rise design
- Added interior and exterior sheathing
height-to-width factors for seismic design
- Added sheathing combination used,
listed under C column legend at bottom of table
- Added cumulative shear force, listed
under V within the Allowable Shear grouping.
- Renamed Wind Dir as For Dir.
- Renamed Response as Crit Resp
- Dragstrut and Holddown Forces
- Reorganized into sections based on
floor levels
- Deleted the Level column
- Added reference corner and load case
column Ld. Case only for low rise wind design
- Components and Cladding by
Shearline
- Added service condition factors for
temperature and moisture
- Reorganized into north-south and
east-west shearline sections
Version 2002a - March 3, 2002 - Design Office 2002
Service Release 1
- Occupancy category
- The building occupancy category is now
correctly implemented in the program and in the log file. Correct
importance factors are applied.
- Site classes E and F for ASCE 7-98
- For class F and class E for Ss >=
1.25, ASCE-7 does not provide site coefficients Fa and Fv. Two new
input fields have been added to the program to allow input of these
parameters as determined from geotechnical analysis. Classes E and F
have been added to the dropdown list.
- Soil profile type F for UBC
- For soil profile F, UBC does not
provide site coefficients Ca and Cv. Two new input fields have been
added to the program to allow input of these parameters as
determined from geotechnical analysis. Class F has been added to the
dropdown list.
- 2000 version project files
- Project files create with Shearwalls
2000 are now properly opened by Shearwalls 2002.
Version 2002 - Nov 3, 2001 - Design Office
2002
- Multiple blocks
- The program allows input of multiple
building blocks for ease of initial wall creation, roof modeling,
different levels in one building, and low rise wind load generation.
- Levels information
- Ceiling depth and foundation elevation
have been added to the structure input. The format of the input
fields has been made more demonstrative of the structure.
- Roof module
- The program automatically creates roofs
on each building block, joins the roofs, and allows the user to
change the roof size, position, construction, slope, ridge location
and overhangs.
- Site information
- The now contains a dialog box for the
input of topographic, climatologic and seismologic site information,
and building characteristics such as enclosure and exposure, for
the generation of wind and seismic loads. It calculates enclosure type
and approximate fundamental period based on the building model.
- Building masses
- The program automatically generates
building masses based on user input self weights of walls, roof, floors
and ceilings for use in seismic load generation. The user can enter their
own building masses.
- Wind Load Generator
- The software now generates MWFRS or
C&C wind loads on the entire structure or on specific components
using the ASCE-7 98 procedure for all structures, the ASCE-7 98
procedure for low-rise buildings, or the UBC 97 normal force method.
- Seismic Load Generator
- The software now generates seismic
shear loads on the entire structure or any part of the structure,
based on the mass of specific components. It uses the ASCE-7 98
Lateral-force procedure or the UBC 97 static lateral force method.
- Default Settings
- Default values for wall, floor, and
opening dimensions, and default standard wall, been moved to the new
Default settings page. Settings for initial roof geometry and initial
site information have been added.
- Design Settings
- A design setting has been added to
choose the wind load generation design method. Sheathing capacity
combination choices have been added for seismic design, and the
option of using just the strongest side has been included.
- Results Reports
- Sections for site information, roof
geometry, and building masses input have been added. The format of the
design settings output has been improved.
- Log file
- A log file is output showing
intermediate calculations for wind load generation, seismic load
generation, and rigid diaphragm design.
- Graphics
- Version 2002 makes it easier to select
and segment walls and openings. More tolerance has been added to the
mouse operations.
- Bug fixes
- Crash when attempting to segment walls
right to the end of the wall is fixed.
- Problems with the combination on the
screen of more than two overlapping loads is fixed
- Crash when the user attempts to type in
more than 4 levels is fixed
- Crash introduced in Version 2000b that
occurred while the editing or saving Standard Walls is fixed
- Annoying line that appeared when
creating the first wall has been removed.
- Problem with flexible load distribution
on a cantilevered load, such as for an overhang
- No longer possible to create gaps in
exterior shell of building
- Program were sometimes assigning walls
to the wrong building faces, which would result in loads and forces being
misplaced in the diagram
Version 2000b - Jan 9, 2001 - Design Office Service
Release 2
- New Key code system - refer to the key code
security section for details.
- Zoom Feature
- There are now two buttons on the plan
view bar, one for Zoom In and one for Zoom Out. The program
increases or decreases the viewing area by a certain percentage when
the buttons are pressed, while maintaining the same west and south
view limits. - The percentage that the view is zoomed each time a
button is clicked is specified in the View Settings - the user can
choose a zooming increment anywhere from 1% to 100%.
- Scrolling Difficulties Fixed
- If the view limits were set to zoom
into a region such that scrolling was necessary to see the whole
building, scroll bars did not necessarily appear, nor did they appear for
a CAD import that is bigger than the view limits. ( This was a
problem in Windows 95/98 only ). When an existing file is opened, or when
the view limits are changed, or when a CAD file is first
dimensioned, the program now sets the position of the scroll bars to the
coordinates of the view limits. This way the view that the user sees
on the screen exactly corresponds to the one set in the settings until
the user first uses the scroll bar.
Version 2000a - June 16, 2000 - Design Office
Service Release 1
- Windows 98 Resource Leak
- Using Shearwalls on a Windows 98
machine for a period of time severely depleted the Windows GDI resources,
causing failure of program graphics. This has been fixed.
- Extend walls upwards not available after
saving
- The state of the program with regard to
the "extend walls" feature was not being saved to the
file. Instead, extend walls was being disabled every time a file was
loaded. You are now able to save a file before "extend walls"
is pressed.
- Delete multiple exterior upper floor walls
- If more than one exterior wall on an
upper story was deleted at once a protection failure occurred. This has
been fixed.
- Levels label
- Text on dialog read "Level 1,
Level 1, Level 3 ... "
Version
2000 - Feb 18, 2000 - Design Office 2000
- Multistory design.
- Designs up to 4 stories, transferring
shear, overturning, dead load, and uplift forces down through
structure. Displays walls from any number of floors in elevation
view.
- New Load Types and Profiles
- The user can input wind shear, wind
C&C, wind uplift, seismic or dead loads. These can be point
loads, line loads, area loads, trapezoidal loads, or triangular
loads. These are all displayed graphically next to the loaded
building elements.
- Automatic Load Distribution
- User can input wind loads or seismic
loads to a building face, and these will be distributed to the
shearwalls by the rigid diaphragm method and the flexible diaphragm
method. The user may add forces manually to adjust the automatically
distributed forces.
- Rigid Diaphragm Method
- User has the option to distribute loads
to shearwalls using Rigid Diaphragm Method. User can base the
relative rigidity on shearwall capacity, or manually enter
rigidities.
- Flexible Diaphragm Method
- User has the option of distributing
loads based on tributary width between shearlines. The assumption is
that for irregular structures, drag strut collectors are present to
allow the diaphragms to be oriented in the direction of the loads in
both orthogonal directions.
- Design Codes
- A large number of design settings have
been added to allow the user to implement the applicable design code
(UBC, NBC, SBC, or IBC). The user may override the values from the
design code to conform to local standards.
- Seismic Design
- User enters seismic loads and program
performs separate design for them and for wind loads, or performs a
design using the worst case load for wind and seismic per building
element.
- Leeward/Windward Design
- User can enter leeward wind loads,
windward loads, or loads that apply to either situation. Program
designs for both, and for the worst case per element.
- Dead loads and Uplift loads
- The user can enter dead loads and roof
uplift loads, and these will be transferred down through the
structure. The program will report their value at holddown
locations.
- Holddown and Dragstrut Forces
- Overturning, dead, uplift components of
holddown forces are shown at openings and wall ends, or the user can
choose to combine these. Dragstrut forces are shown at openings and wall
ends. Dragstrut and holddown forces are also reported in an output
table.
- C&C Design
- C&C Design will be performed for
exterior walls that are not designated as shearwalls, and for
shearwalls, the worst case of shear and C&C loads will govern
the design.
- Results Output
- Much improved reporting of design
results, with separate tables for each type of input load; wall
materials, shearlines; shear results; C&C results; wall segments,
openings, holddown and drag strut forces. User may choose which
tables from which design runs to view or print.
- Elevation View
- Elevation view selectively displays
shear flow, dragstrut forces, holddown forces, and C&C loads.
Sheathing and nailing capacities are displayed next to the design
materials.
- User interface
- Interactive graphics have been
improved, making it easier to select, resize, and move walls. It is also
easier to enter wall materials. Toolbars have been added to each window
to allow user to show or hide items on the screen or printed output,
and to quickly change settings.
d)