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Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 9.3 and may not reflect current program behaviour.
The program now implements the new CSA O86-14 Engineering Design in Wood Standard. As the National Building Code referencing CSA O86-14 is not yet released, and provincial building codes have not yet mandated the use of O86-14, the program also allows you to continue using CSA O86-09.
Input
A drop list box called Design Code has been added to the Design settings in the Design procedures data group, with the choices
CSA O86-09/ NBC 2010
CSA O86-14/ NBC 2010
The Design Settings output has been changed from showing only the National Building Code edition to showing CSA O86-09 / NBC 2010 or CSA O86-14 / NBC 2010.
It shows the edition of the O86 currently being used, and the fact that it is the May 2014 printing of the CSA O86-14, in the About Sizer box accessed from the Help menu and in the Building Codes box accessed from Welcome Box. In the main body of the Welcome box, it indicates that either of these codes can be used.
The references to the CSA 086 design code clause numbers in the input forms and screen messages, and in warnings, design notes and other program output, have been updated to show the 2014 edition clause numbers when CSA O86-14/ NBC 2010 is chosen as the design setting. It continues to show 2009 edition numbers when CSA O86-09/ NBC 2010 is chosen.
The on-line Help has been updated to refer to the CSA O86-14 design code clauses. The unrevised online Help is also included in the installation to allow you to use Help that references O86-09.
The Design Office installation the on-line 2014 edition of CSA O86 in .pdf form has been made available. program now allows you to view either the CSA O86-14 or CSA O86-09 design code, and both documents are included in the Design Office installation.
The Welcome box now indicates that both design codes are available. The Help About Shearwalls box and the Building Codes box show information about the currently selected design code.
The Building Codes box and the message that appears when you enter more than 4 storeys have been updated to refer to the 5- and 6- storey provisions in the NBC 2015 rather than the BC Building code. Information about continuous hold-down systems and rotational deflection required for taller structures has been added to the Building Codes box
Information about wood shrinkage and irregularities not considered has been removed from the Building Codes box.
In all messages, notes, warnings, and output tables, the program shows design code clause numbers for either O86-14 or O86-09, according to which is selected.
The rest of the changes described in this section occur when CSA O86-14 is selected as the design code edition in the Design Settings, unless otherwise indicated.
For wood-based structural panels, the program now calculates Vrs via the expressions in O86 11.5.1
Lateral nail resistance:
φ vd JD ns Jus Js Jhd Ls
Panel buckling:
φ vpb KDKSKT Ls (panel buckling)
The worst case of these two equations is determined for each side of the sheathing, and then the two sides are summed.
Previously only the expression
φ vd KDKSF Jub Jsp Jhd Lw
was used.
The following subsections apply to wood-based panels only; the procedure for gypsum wall board has not changed.
The calculation of Vhd, which is just Vrs without the Jhd factor, for use in determining the Jhd factor, considers both the lateral nail resistance and the panel buckling equations, despite the fact that Jhd appears only in the nail resistance equation. (This was decided upon after consultation with the design standard authorities.) The procedure for combining sides is thus:
The resistance factor φ has increased from 0.7 to 0.8, the value that has always been used for nail resistance, for both panel buckling and nailing equations.
Vrs from O86 11.5.1(b) is calculated as follows:
Unit lateral Vd is now calculated via the equation Nu/s, where Nu is the factored unit lateral nail strength in N from O86 12.9.4.1 and s is the edge nail spacing, rather than tabulated values based on sheathing thickness and nail sizes.
The notes to O86 09 9.4.4 representing strength adjustments for special cases are no longer applied.
Nu varies continuously according to nail length, diameter, and penetration depth, whereas Table 9.4.4 provided only a very limited number of choices, conservatively specifying a minimum nail diameter for which the tabulated values were valid, and a required penetration depth.
This means that the choice of nail size has a much bigger impact than before; the program has added more nail sizes and types to the program as described in .
Nu from 12.9.4.1 is given by nu KSF KD KT , with the K factors implemented as follows.
The service condition factor KSF comes from O8612.2.1.5 for connections. The same service factor is applied to all walls in the structure based on the in-service and fabrication conditions input in the Design Settings. Green fabrication or wet service conditions correspond to moisture greater than 19%.
For changes in the service factor input, terminology and calculations, refer to .
This is set to 1.15 for both wind and seismic. It does not represent a change from the previous version.
As the factor for studs is one unless they are incised there is no program input of treatment factor and KT = 1, always.
nu is calculated by the yield mode equations in 12.9.4.2. The following inputs correspond to a single shear plane plywood-to-stud connection:
This is the sheathing thickness in mm.
As input in Wall Input view.
Determined from density of stud and nail diameter.
Nail length minus the sheathing thickness. The ability to include gypsum wallboard underlay in the sheathing thickness has been added because of its effect on nail penetration – see for details.
Determined from nail diameter.
Determined from density of sheathing material (CSP, DFP, or OSB), and nail diameter.
According to 11.8.1, in order to ensure ductility, the wall should fail in modes d, e, or g from 12.9.4.2.
For each wall design or candidate design for unknown parameters, the program will record whether the lowest value of the nail failure modes for either side of the shearwall is not d, e or g.
If a completely specified wall, or for a failed wall arrived at when all unknown possibilities are exhausted, fails because of the ductility check, the symbol # appears beside the wall capacity in the shear results table and a note below the table indicates a design failure and the reason.
The program passes over candidate designs for which the ductility check fails. If the program cannot find a design, and at least one wall that had sufficient capacity was rejected because of nail ductility, the symbol @ appears by the wall capacity and a message below the table informs you what happened.
This factor is set to 1.3 at all times.
As mid-panel shearwalls are not to be included in this version, the value of ns is always 1.
The nomenclature for this factor has changed, but in terms of engineering design there have been no changes to program
This factor is implemented according to O86 11.4.1, a formula based on panel edge spacing. It is less than one for spacing less than 150 mm, and equal to one for larger spacing.
Vrs from O86 11.5.1(c) is calculated as follows:
The following parameters are used in the equation for specified panel buckling strength vpb:
The axial stiffness values Ba,90, Ba,0 from tables 9.3A ,9.3B and 9.3C for each plywood or OSB thickness, and no. of plies for plywood and panel marking for OSB, have been added to the program. The value Bv was already in the program for use in deflection analysis. .
For both Ba and Bv , if you enter a larger sheathing thickness value than is in the dropdown list, but one in table 9.3A-C , the correct value for that size from 9.3A-C is used. Previously, for Bv the program used the value from the largest thickness in the dropdown list. If you type in a larger thickness than is in the table, the input is rejected with a warning.
As the buckling resistance gets larger as the smallest dimension of the sheet used gets smaller (because of the "b" in the denominator of the vpb equation the critical panel), the critical panel within the a segment is the largest one. Therefore, full 4 x 8 sheets are used for those segments that are larger than 4 feet wide for vertical sheathing and 8 feet for horizontal orientation. For smaller segments, the size of the largest component panel is determined, for example a 6 foot segment uses 4’ x 6’ for horizontal sheathing and 4’ x 8’ for vertical. A segment 3 feet wide uses 3 x 8 for vertical and 3 x 4 for horizontal.
For wet service conditions as input in the design settings, the program uses KS from Table 9.4.2 and applies factor of 0.80. Wet fabrication conditions to not apply to plywood.
Note that wet service conditions are no longer allowed for OSB or gypsum wallboard, see .
Due to the rarity of use of treatment factors for plywood and OSB, the program does not include an input for treatment and this factor is always 1.0.
This is set to 1.15 for both wind and seismic.
In the Shear Design table, the total force on the wall or segment Fv and the corresponding capacity Vr have been removed from the table to make room, and because they are not particularly useful to the designer.
Where the table previously had one unit capacity Vhd/L, it now shows unit capacities for nail resistance and panel buckling separately, headed by Vhd (vd) / L and Vrs (vpb) / L, respectively. The table shows values for interior and exterior sheathing sides for each. The combined Vrs/L is still shown.
Corresponding changes have been made to the explanatory legend below.
The Jsp column and legend entry have been removed from the Framing Materials table, as it no longer applies for O86-14.
In the Sheathing Materials table, the Jub heading and legend description have changed to Jus.
Design notes appear below the Sheathing Materials table that indicate sheathing and nailing requirements, and adjustments to strength for particular configurations. The following changes have been made to these notes:
Add design code references 11.4.4 and 9.4.4 for 086-14 and O86-09, respectively. Add sentence saying unblocked panels must be staggered.
Add design code references 11.5.3.4and 9.5.3.4 for 086-14 and O86-09, respectively. Clean up character spacing issues.
Add design code references 11.5.3.2 and 9.5.3.2 for 086-14 and O86-09, respectively. Change "wide" to "thick" to make stud dimension clearer. Show metric or imperial thicknesses according to units selected. Clean up character spacing issues
This is Note 1 or Note 2 in Shearwalls, and is from the asterisk (*) under O86-09 Table 9.5.1A. This note has been removed for the O86-14. Minor formatting improvements for 09.
In Shearwalls, this is Note 3 for O86-09 and Note 1 for O86-14, and is from the symbol Ɨ under O86-09 Table 9.5.1A. Show metric or imperial thicknesses and nail spacing according to units selected. For imperial, say "minimum 3-by or double 2-by". Add 11.5.3.5 a reference for O86-14. Minor formatting improvements.
In Shearwalls, this is Note 4 for O86-09 and Note 2 for O86-14, and is from the symbol ǂ under O86-09 Table 9.5.1A. Show metric or imperial thicknesses and nail spacing according to units selected. For imperial, say "minimum 3-by or double 2-by". Add 11.5.3.5 b reference for O86-14. Minor formatting improvements.
In Shearwalls, this is Note 5 for O86-09 and Note 3 for O86-14, and is Note (3) under O86-09 Table 9.5.1A. Add 11.5.3.5 reference for O86-14. Minor formatting improvements.
In Shearwalls, this is Note 6 for O86-09, and has been eliminated for O86-14, as there is no Jn factor.
In Shearwalls, this is Note 7 for O86-09, and has been eliminated for both design codes. Refer to for more details.
In Shearwalls, this is Note 8 for O86-09 and Note 4 for O86-14. Add design code references 11.5.3.3 and Table 9.5.1A Note 6 for 086-14 and O86-09, respectively. Fixed problem with panel marking output, refer to , (Change 216).
Upon design, the program outputs a new file containing intermediate design data, called [projectname].swd. A menu item and toolbar button each called Detailed Shearwall Design access this file and show it in a reader similar to the one showing the Load Generation and Torsional Analysis log file.
The output starts with a table showing all the symbols used in the equations governing shearwall design and shown in the headers for the tables in this file. Each line shows the symbol, definition, two columns for units employed, and the reference to the O86-14 clause where the symbol is defined or used.
The first unit is for those that appear in the equations as published in the O86, and the second one is for the units that are shown in the tables below For imperial units, the first set will be metric and the second set imperial. For metric units, the columns usually show the same units, except for cases that the table shows for example kN rather than N for formatting convenience.
The symbols are followed by a section showing the equations employed, along with the design code clause reference for each one.
There are two lines of data that are the same for all shearwalls. The first line shows data that can’t be changed by the user, the second shows ones that can, or may be in future versions of the software. These lines contain the safety factor φ, diaphragm factor JD, duration factor KD, service factors KS and , treatment factors KTp and KTn , and number of shear planes ns.
For each shearwall, there is a line for data that are independent of the wall segment or sheathing side, showing wall height and total shear force Vr in each direction on the wall.
For each shearwall, there is a table showing the data needed for panel buckling Vrs calculations from O86 11.5.1(c). There is a separate line for each shearwall segment between openings and for the interior and exterior sheathing sides. The data shown are segment length, sheathing thickness, shear force per unit length, unit panel buckling strength vpb, panel buckling factor Kpb, critical panel dimensions a and b, panel axial strengths Ba0 and Ba90 , shear through thickness rigidity Bv, and parameters η (eta) and α (alpha).
For each shearwall, there is a table showing the data needed for nailing Vrs calculations from 11.5.1(b). There is a separate line for interior and exterior surface. The data shown are nail diameter, panel thickness, nail penetration length, shear strength Vhd per unit length, unit shear strength vd , fastener spacing factor JS, unblocked factor JUs, nail spacing, factored nail strength Nu, yield modes a,b, d, e, f and g for unfactored nail strength nu. marking the critical mode with an asterisk (*) and indicating whether it is ductile or non-ductile.
As the calculation of shear strength Vrs now depends on the exact nail diameter and nail penetration length, and given the prevalence of power driven nails, the program has greatly expanded the selection of nails available in Shearwalls. Unless otherwise indicated, these changes apply regardless of whether O86-09 or O86-14 is selected as the design code.
Previously the nail types available for structural sheathing were Common wire nails and Non-standard nails. The program now allows the following choices
Common wire nails
Spiral nails
Ring nails
Power-driven nails
Power-driven nails correspond to the previous Non-standard nails, with changes to functionality described below.
The following table shows the correspondence between diameter and length for each fastener type now available in Shearwalls:
Length (in) |
Length (mm) |
Common wire nails |
Spiral nails |
Ring nails |
|||
|
|
in |
mm |
in |
mm |
Nom in |
Nom mm |
1-3/4 |
44 |
- |
|
- |
|
0.109 |
2.769 |
2 |
51 |
0.113 |
2.87 |
0.120 |
3.048 |
0.120 |
3.048 |
2 |
51 |
- |
- |
- |
- |
0.134 |
3.404 |
2-1/4 |
57 |
0.113 |
2.87 |
- |
- |
- |
- |
2-1/2 |
64 |
0.131 |
3.33 |
0.120 |
3.061 |
0.134 |
3.404 |
3 |
76 |
0,148 |
3.76 |
0.135 |
3.429 |
0.148 |
3.76 |
3-1/4 |
83 |
0,148 |
3.76 |
0.135 |
3.429 |
- |
|
For CSA O86-14 design, the program no longer limits the fasteners used based on sheathing size. All nail sizes are allowed for all sheathing thicknesses. For CSA O86-14, only nails that meet the min. penetration in Table 9.5.1A are allowed.
For ring nails, the value shown for diameter is the size of the wire the nails are made from. The nominal values are shown in the user interface, but for design, the program subtracts 2 mm = .0075" to arrive at the root diameter to be used for the design equations.
In previous versions of the program there is a one-to-one correspondence between nail length and diameter. Now there are now two diameters for 2" ring nails. In this case, if you select ring nails, the program selects by default the first of the diameters, 3.048mm, which you can then change. This diameter is be used for design for unknown nail length when the cycle reaches 2".
The following table shows the correspondence between diameter and length for power-driven nails available in Shearwalls:
Length |
Diameter |
||
in |
mm |
in |
mm |
1-7/8 |
44 |
0.131 |
3.33 |
2 |
51 |
0.113 |
2.87 |
2 |
51 |
0.131 |
3.33 |
2 |
51 |
0.120 |
3.048 |
2-1/8 |
54 |
0.48 |
3.76 |
2-1/4 |
57 |
0.92 |
2.33 |
2-1/4 |
57 |
0.99 |
2.50 |
2-1/4 |
57 |
0.105 |
2.68 |
2-1/4 |
57 |
0.113 |
2.87 |
2-3/8 |
60 |
0.113 |
2.87 |
2-1/2 |
64 |
0.120 |
3.048 |
2-1/2 |
64 |
0.131 |
3.33 |
2-5/8 |
67 |
0.148 |
3.76 |
2-3/4 |
70 |
0.148 |
3.76 |
3 |
76 |
0.120 |
3.048 |
3 |
76 |
0.131 |
3.33 |
3 |
76 |
0,148 |
3.76 |
3-1/4 |
83 |
0.148 |
3.76 |
Previously the lengths and diameters available for non-standard nails were the same as those for common wire nails, the difference being that you could enter your own value for non-standard nails.
The program now allows you to specify unknown length for power-driven nails, and the program cycles through the possible lengths to achieve design.
If a known nail length is selected, the program lists the diameters for that known nail length only and select the first by default, as the program does not cycle through nail diameters. .
If unknown is entered as the nail length, then all possible nail diameters are listed. If you select one of these nail diameters the program will continue to show unknown for nail length, and when the design loop runs, it will only design for nails that have that diameter.
If the diameter is unknown and you in a nail length, the program selects the diameter corresponding to the closest nail in the list to the nail length that was typed in.
As per NBC Table 9.23.3.5.A, you cannot enter a nail length less than 1.75" – the program will revert to the previous value and issue an explanatory message. Previously there was no lower limit on nail length in Shearwalls.
As per the intent of O86 14 (see ), you cannot enter a nail diameter greater than 3.76 mm – the program reverts to the previous value and issues an explanatory message. Although previous to O86-14 there was no upper limit, this limit is imposed regardless of whether O86-09 or CSA O86-14 is selected in the Design Settings.
When the length and diameter are left as "Unknown", if when cycling through lengths the program arrives at one that has more than one diameter, it chooses the one corresponding to the common wire nail of that length.
Previously, in the Sheathing Materials table, the size of a non-standard nail was rounded off and converted to the closest fractional size, one which is often the same as a standard nail. Now, power driven nails are output in decimal format to distinguish them from standard nails that are in fractional format.
The program is was using nail diameters listed in the CSA O86, from the CSA B111 standard, however it has been determined that these diameters do not correspond to the wire gauges currently used to manufacture nails, which are from the ASTM F1667 standard. Several limitations are based on the nail diameters, such as O86-14 11.4.5.5 that limits nail diameters when anchorages are used to 3.25 mm, and 11.3.1.1, which says that shearwalls must use nails 3.66 mm or less.
We have changed those limitations 3.33 mm and 3.76 mm, respectively, to correspond to the nail diameters we use in the program for nails of the corresponding lengths.
The messages that appear when these limitations are imposed have been modified to explain this decision. In addition, if a nail between 3.66 and 3.76 is used in design, or a nail between 3.25 and 3.33 when Jhd < 1, a new note appears below the sheathing materials table saying that the nail conforms to the intent of 11.3.1.1 or 11.4.5.5.
The program now includes the ability to gypsum underlay because it affects nail penetration and therefore shear strength for O86-14. This feature is also available if O86-09 is selected, and in this case affects whether a nail length achieves minimum penetration for shear resistances in Table 9.5.1
Choices of no gypsum underlay, ½", and 5/8" underlay have been included in the Sheathing data group of the Wall Input form. The default is None.
For O86-14, the penetration depth used to determine the nail strength described in is reduced by the thickness of the underlay.
For O86-09 the set of nail lengths listed in the input control and used to cycle through for unknown design does not include nails that do not meet min. penetration depths in table 9.5.1A.
A column "GU" has been added to the Sheathing Materials by Wall Group table showing the gypsum underlay thickness, with an explanatory legend entry.
The following changes apply to the calculation of nail slip deflection en, which is one of the components of shearwall deflection:
For CSA O86-14, instead of the table from O86-09 A.9.7 the program implements the equation from O86 09 A11.7., which depends on the same inputs – spacing s, diameter d, and shear force v.
For green fabrication conditions, the program multiplies the values from the equation by 2.0.
Note that there is no longer an upper limit on the load for which en values are tabulated, so that the program no longer issues warnings in the Design Results that the load per fastener is too high, and has removed this from the list of things that the Design Summary page does not handle.
Previously, the program uses a constant deflection of 0.03 inches = .0762 mm. The O86- 14 design code says to use 0.76 mm. This slight adjustment has been made.
Refer to for changes to restrict the use of GWB to dry service and fabrication conditions.
The Design Setting Materials Restrictions for Anchorages has been removed from the program, and user interface no longer contains a restricted set of sheathing thicknesses, nail sizes, or nail spacings based on these settings. Given the new shearwall design equations based on nail size and penetration, it is no longer practical to predict ahead of time what materials cannot be included due to the restrictions in 11.4.5.5 regarding the applicability of Jhd < 1.
The program now behaves as if the setting Over-ride hold down selection to achieve design is always selected. In other words, unless you have specified in the Wall Input view that hold-downs are to be used, the program applies hold-downs only where needed to achieve design, otherwise anchorages are used.
Upon reading project files from previous versions, the program will reset the materials restrictions setting to Over-ride hold down selection to achieve design, so that the behaviour of these projects will change.
The following changes apply to when gypsum wallboard is used as a shear-resisting material.
O86-09 Table 9.5.4 for Maximum Percentage Gypsum Wallboard, which previously applied to both wind and seismic design, has been moved to O86-14 11.8.8, a section that is for seismic design only. Accordingly, for wind design the program no longer calculates the gypsum wallboard percentages, the Maximum Percentage Gypsum table is no longer output, and design failure warning messages no longer shown on the screen or in the results output.
This change has been implemented regardless of whether O86-09 or O86-14 is chosen as the design code, as WoodWorks has been informed that it was always the intention that these restrictions applied to seismic loading.
A sentence has been added to O86 11.8.8 saying that the Rd and Ro values can each be reduced to 1.0 if the GWB percentages are exceeded. Previously it was an absolute requirement that the GWB percentages not be exceeded. The program therefore no longer displays a Maximum Percentage Gypsum Wallboard table for seismic design if Rd and Ro are both less than or equal to 1.0, outputting an explanatory note instead.
The operation of various screen warning messages and output warning notes that appear when gypsum wallboard limitations have been modified to take the possibility that Rd and Ro both equal 1.0 into account.
A sentence has been added to O86 11.8.8 saying that gypsum wallboard does not contribute to seismic resistance if the interstorey drift ratio is greater than 1.0%, that is, if the drift of one storey relative to another is greater than 1% of storey height, as opposed to the 1%, 2% or 2.5% allowed now by NBC 4.1.8.13.(3) according to building type.
To implement this, the program now records the largest drift of any shearline with GWB that is active for design on each storey and force direction. In the storey drift table, if some shearlines on the level/direction indicated have GWB and some do not, for that level/direction the worst case GWB deflection and shearline with the maximum deflection are both output, unless they are the same shearline.
If a shearline fails because it has active GWB and its storey drift is between 1% allowed for gypsum and the percentage allowed for the building type as per NBC 4.1.8.13 (3), then double asterisks (**) appear at the design ratio and a modified failure warning appears.
For gypsum wallboard, the shear-through-thickness value Bv has changed from 7005 N/mm to 7000 N/mm, as per CSA O86 11.7.1.2. Previously O86 did not provide guidance for this value, and Shearwalls was using 40,000 lbs/in converted to N/mm. The program still displays 40,000 lbs when imperial units are chosen.
This change is in effect regardless of whether O86-09 or O86-14 is chosen as the design code.
The fabrication moisture content for which any value greater is considered to be green in O86-14 Table 12.2.1.5 and a non-unity factor is applied, has changed from 15% to 19%. This change has been implemented to the service condition factor applied to nail withdrawal and shear strength calculations. In addition the default for new files has changed from 15% to 19%.
Refer also to Moisture Conditions Description in Design Settings Input and Output.