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Notch design has been expanded and improved significantly, with the addition of interior notches, notches on sloped members, and other smaller improvements.
The program now allows for notches to be located at interior supports in multi-span and cantilevered members. This allows for common situations such as a birds-mouth notch in a roof rafter, especially in conjunction with improvements made in the treatment of notches for sloped members (see immediately below). .
Interior notches can be notched at the lower surface only; top notches are not allowed.
According to NDS 3.2.3.2, the stiffness of a bending member is practically unaffected by notches with depth less than or equal to 1/6 beam depth and length less than or equal to 1/3 beam depth. Accordingly, these limits have been applied to interior notches.
The input fields that were previously in their own data group have been moved to the Supports for bearing design data group, which has been renamed Supports for bearing and notch design.
The control for Left end, Right end, or Both has been eliminated. Instead, the mechanism for choosing supports for bearing design is now also used to choose the supports for notch input. That is, the control Applies to is used to specify the support(s) that the notch inputs apply to.
The program applies the unsupported length e to both sides of an interior notch, except for sloped beams, for which e is applied entirely at the upper side of the support, as is the case with a birdsmouth notch.
The program rejects input of interior top notches and resets the input fields without notifying you. It is possible to apply top notches to both ends by selecting "All" supports; the program simply omits the interior notches.
Shear design is performed using 3.4.3.2. These procedures had already been implemented for end notches.
For interior notches, the program uses the net area to calculate the section modulus S in the calculation for moment stress using 3.3.2, as required by 3.1.2.1.
Note that this had not previously been done for end notches, because moments at the end are zero. The rare case of applied moment at a notched member end has now also been handled (see Bug 2845, below).
If the input notch exceeds the notch size limitations, upon design the program:
The notch output in the Materials Specification of the Design Check report is now formatted in a similar manner to supports for bearing design, that is, the supports are numbered sequentially from the left and of the beam and the information for the notch given after the support number if there is a notch for that support.
The program now considers the slope angle of the beam when drawing notches in sloped members.
The program did not check whether the input of the unsupported length e was compatible with the input notch length dn for sloped members, and sloped member notches were not accurately drawn on the member.
The input notch depth for sloped notches is the dn value as defined by NDS 3.4.3.2, that is the distance perpendicular to the member grain.
Note that this distance must be calculated from the vertical notch depth, which is the depth likely to be specified to installers because they lay out the notch using a square with the marks on the edge of the wood corresponding to the ratio of rise/run of the sloped member.
This is the horizontal distance from the edge of the support at the upwardly sloping end of the beam to where it interests with the lower edge of the beam. If an unsupported length is entered that is not possible given the input notch depth, the depth is changed to accommodate it, and vice-versa.
As with unnotched members, the dn and e you input in Beam View is used to compute shear reduction in 3.4.3.2.
The program now draws notches on sloped so that a member supporting a sloped member fits into a notch entered for that support. Note that for reasons of economy of space on the screen and printed output, the beam angle in the drawing is not always the actual beam angle, so that notches on the drawing often do not penetrate the member as they do the actual beam.
When the bearing reaction at a notched support is zero the notch is sometimes considered in tension when it should be in compression and vice versa. Whether the notch is in tension or compression determines whether 3.4.3.2 (a) or (e) is used for notch design.
Note that it is quite rare for the mechanics of the beam to be such that the reaction of the support is precisely zero, so this bug is very unlikely to have occurred in a practical design.
When a notch was entered that exceeded the 1/3 span length limit, the program would silently change the notch to 1/3 span length in the design, but not update the notch input field or inform the user. Now it changes the input to 1/3 span length and issues a warning message.
The bending check for notched beams was using the section modulus Sx reduced for net area of an end notch when calculating the moment capacity in the interior of the span, when it should only have been used at the notched ends of the span. This occurred only if a notch was present of the left-hand side of the span, and has been corrected
The program now uses the net section for moment design when an applied moment is entered right at the end of the member that is notched at the end. Note that this condition is quite rare in practice.
Notch length and notch depth input fields did allow imperial fractional input, because they updated, imposed limits, and changed related fields every time a character is entered, for example when trying to enter a 13/16 notch it disallowed it when "13" was typed. This has been corrected and fractional input is now supported.
If you entered a top-edge notch that is shorter than the distance from the outer edge of the support to the support point based on required bearing, the program could misidentify a compression notch as tension and vice-versa, as it does not have the loads analysis information outside the design span. This problem is restricted to the rare case that a notch on the upper face is loaded in tension, unless zero is entered as the unsupported length for compression notches.
A simple workaround to the most common instance of this problem is to simply not enter a short notch on the compression face, as there are no design implications of such a notch. The problem has been corrected nonetheless.
The following changes pertain to the Beam Stability Factor CL in NDS 3.3.3 and the treatment of lateral beam support.
Even though the NDS 3.3.3.4 says that beams must be laterally supported at points of bearing, several users have indicated that they would like to design beams that are either not laterally braced at interior points of bearing or that are insufficiently laterally supported in their engineering judgement, and therefore consider the full beam length as the unsupported length Lu for the calculation of the CL factor.
Noting that mechanics of the buckling equations used to derive the CL factor require only that the beam be fixed against rotation at two points, and that the American Wood Council Technical Report 14 includes a multi-span beam example with unsupported length as the entire length of the beam, Sizer has been modified to allow the choice of whether a beam is or is not laterally supported at interior supports.
A checkbox Laterally supported at support has been be added to the Supports for bearing and notch design box. It behaves similarly to the Bearing at support end checkbox in terms of being checked, unchecked, disabled and enabled when multiple supports are selected at once in the Applies to box.
The program ensures that end supports and cantilever supports are always checked, to maintain two points at the end of each beam that are fixed against rotation.
The existing output under the materials specification in the Design Check summary which says "at supports", has been modified to say "at all supports", "at end supports", or e.g. "at supports 1,2, 4"
If the checkbox is not checked, the program does not consider the interior support when determining the unsupported length Lu. If At supports is chosen as the lateral support option, all interior supports are unchecked, the program uses the full beam length as the unsupported length. If a lateral support spacing greater than a span length adjacent to such as support, the lateral support length is used instead of the span length.
If the option Use zero moment points is selected as well is unchecking lateral support as a support, the distance between zero moment points to the left and right of the support is used if it is greater than any span length.
In the beam drawing, for interior bearing supports that are not laterally supported, there is no longer a lateral support symbol at the bearing support.
The program now offers a choice of whether using the full member width or the width of a single ply for the lateral stability calculations for built-up beams. .
Research has recently shown that nailed and bolted beams have at most 30% composite action effect in terms of resisting torsional buckling, and for this reason it is extremely non-conservative to use the full member width as b in the expression for the slenderness ratio RB which is used to calculate the stability factor CL in NDS 3.3.3.6.
In the Design Settings, a data group called Lateral Stability factor CL has been added, a set of selection buttons has been added to allow you to choose whether the full member width or single ply width is used for the CL factor.
The default value for this setting is single ply for new project files and full member width for files from previous versions which did not have the setting. In that case, the program issues a warning when the file is loaded.
When single ply is chosen, the value b used in the slenderness ratio RB in 3.3.3.6 is the width of a single ply, that is, assuming no composite action effect. This affects both the limit of 50 for the slenderness ratio itself, and the use of value RB in calculating the lateral stability factor CL via FbE.
For built-up beams, the program appends the choice of single ply or full beam width to the existing line in the CALCULATIONS section of the Additional Data giving the parameters for the lateral stability calculations (Feature 172, below).
In the CALCULATIONS section of the Additional Data in the Design Check output, the program now shows the unsupported length Lu, the effective length Le, and the slenderness ratio RB for the calculations of lateral stability factor CL in NDS 3.3.3, and if applicable, the built-up member width option (Feature 209, above) and/or the zero moment point option (Bug 2695 from version 10.2, below).
In the CALCULATIONS section of the Additional Data output, the program was showing identical lateral stability detail lines for positive and negative moment for columns if such moments existed. As we assume both edges of a column are supported the same way, this was unnecessary, and one of the lines has been removed. In the case that there is only a positive moment, the "(+)" symbol has been removed.
The following problems regarding the drawing of lateral support symbols have been corrected:
Sloped multi-span beams with a specified lateral support spacing is drawing the lateral supports with a large gap between the lateral supports and the beam.
The starting point for interior spans is now be the middle of the support, not the right edge.
A lateral support symbol is now placed at the end of the beam.
In order to facilitate approximate cost comparisons of different sizing options, the program now outputs the wood volume of the member.
A column has been added to the design summary output of suggested sections giving the wood volume of the member in cu. ft or m3. To make space this column, we have removed columns that do not apply to the type of member, such as the axial tension column for beams. Because bearing lengths are not necessarily known when these sections are examined, the length used by the program is the one input in beam view and could therefore be the length of the design span, clear span, or full span. Only if full span will be chosen will the result be the precise volume of wood in the member, however, in the other cases, the results are adequate to serve as a comparison of the different sections.
The volume of wood in cu. ft or m3 is given after the total beam length in the materials specification of the Design Check output. In this case, the full length of the beam is used to compute the volume regardless of the chosen span type.
The following problems with bearing and supporting members have been corrected.
If you typed in a length like 1.113 in the bearing length input, the program rounded to the nearest 1/8th of an inch when exiting the view then entering it again, or when it was updated for other reasons. This created problems in conjunction with the notch length field, which updates based on the bearing length, but doesn’t' round the same way. The bearing length input field now operates like other inputs.
The program was showing the width of a single ply as the bearing width for multi-ply members. Now in this case it does not show a bearing width, as it is assumed to be the main member width if not showing.
For SCL materials oriented as planks, the program did not use the weak axis Fcpy value for design, nor output it in the Modification Factors table of the Additional data. Because SCL has not been tested for oblique angles, for any angle between 0 and 90 the weak axis value now applies.
Furthermore, supporting members designated as sill plates now use weak axis Fcpy
The dimension line for clear span for cantilevered beams wasn’t showing the gap at the support.
The load combinations for bearing design are now spelled out in full in the Additional Data section, similar to other load combinations for other design criteria.
When the selection for support is Non-wood the program n longer shows the Bearing length = column width phrase in the materials specification of the design check report, because in that case there is no bearing design.
In Reactions and Bearing table, under Resistance, Supports has been changed to Support for consistency with other output.
When the member supported is a column, the program showed the incorrect wet service factor CM for the supporting member in the Factors table of the Additional Data section of the Design Check Calculation Sheet. The value shown was the factor for parallel-to-grain compression fc , instead of the one for perpendicular-to-grain compression fc┴ . These factors are found in the NDS Supplement, Tables 4A-D and 5A-D.
This is just a reporting issue that did not affect design, and has been corrected.
In the Critical Load Combinations section of the Additional Data, the program was showing a bearing load combination at the free end of a cantilever. This has been removed.
A Preference Setting has been added to allow you to show the design ratio in the Force vs. Resistance output as a percentage, e.g. 87.1 %, rather than a ratio, e.g. 0.87.
The default value for the setting is to continue showing the ratios as a decimal value as in previous versions of the program.
Note that there is 10 times greater precision in reporting the design ratio, so that when it is for example 1.002, the report will show a failed design of 100.2% when percentage is chosen, but a passing design of 1.00 when ratio is chosen.
Instead of listing the various physical units, like lbs, kN and plf, in the heading to the table of the Design Check output, the program now lists the unit used for each design criterion in a new column in the table, thus associating the unit used with the design criterion.
In the Concept mode Results by Member design summary, the program now outputs the length of each member, by appending it to the section size, e.g. 6x6x12’.
The program now indicates in the third line of the materials specification in the Design check output whether the member is defined as a Beam and Stringer or as a Post and Timber in NDS 4.1.3.3 and 4.1.3.4 respectively. These definitions determine which strength properties NDS Supplement Table 4D are used.
If a custom section is two thin to be in either category, then no category is output and a warning appears in the output. Refer to Bug 2797 to changes made to the warning messages that can appear.
A warning did not appear if you entered a custom size for a lumber database that is in fact a timber size according to the definitions in NDS 4.1.3. However, a warning does appear when the reverse is true.
For some cases, such as bending, the lumber sizes are stronger, and for some such as shear the timber sizes are stronger, so there is always a non-conservative error if the wrong grade properties are used. A warning is now shown in both cases.
Also for MSR if a section that is too thick for MSR is entered, the warning saying that the member is too thin for the timber database was shown instead of the MSR message. This has been corrected.
For columns, lines appeared in the Materials specification of the Design Check output saying full support at "top" and "bottom", regardless of the actual support conditions and the fact that top and bottom do not apply to columns. 'They have been removed
The columns for Axial and Combined design criteria, which apply only to columns, have been removed from the Design Summary list of suggested sections for beams
When either of the checkboxes All live loads are construction loads or All roof live loads are construction loads is checked, the program applies a limit of 75 rather than 50 on the slenderness ratio when computing the column stability factor CP, as per NDS 3.7.1.4.
We now include the absolute deflection limit in the Default settings so that it can be saved as default for new files. If a value of 0 is entered, then there is no absolute deflection check. It is possible to enter an imperial value as a decimal or a fraction.
The fire resistance procedures for beams and columns from 722.6.3 have been removed from the IBC. We have decided to keep these procedures in the Sizer program for the time being and add "2012" to "IBC" in the description of the option in Beam View.
Starting with version 9 of the program, after typing in a value like 10.001 to indicate you want a real member width or depth, the program designed for the nominal depth corresponding to the rounded off number, in this case 9.25 instead of 10. It also failed to update the unit label for the input value to show "in." rather then "nom. In." These problems have been corrected.
For shear design, the program checked biaxial design for oblique members by adding the design ratios for the x and y axis, but this has no physical justification and has been removed from the program.
Instead, the program checks the shear stress against capacity in the x- and y- axis directions only. The actual critical shear stress occurs in another plane, and not necessarily parallel to the load.
Due to the complexity of the calculations and the unlikeliness of shear design governing for oblique members, which are rarely notched the program does not attempt to determine the critical shear plane, instead issuing a design note cautioning you that the maximum shear is not one of the shear components shown.
In the Calculation section of the Additional Data report, the value V is now called Vmax, to indicate how it relates to Vdesign.
According to the IBC equations, a negative value can appear for the fire endurance time for beams whose width is greater than depth. If this occurs, then the program now sets the time to zero, and adds any fire protection time to zero rather than the negative value.
When a member which is supported by multiple ply members was exported from Concept mode to Beam or Column mode, the program assumed the supporting member has only one ply when assigning a bearing width. Now, it assigns an unknown bearing width, as plies are not input into concept mode groups and the program assumes plies are unknown.
Note that the program does not export the widths or depths of supporting members as they were designed by Concept Mode - if they were unknown in concept groups, then they are unknown in the exported member.
In Column Mode Design Check output the Ke x ld value for lateral stability showed inches as the unit, although the value was in feet. This has been corrected.
The note under the Load Table indicating that the maximum reaction shown is from a different load combination than the critical one referred to the Canadian load duration factor, KD. It now says CD.
The following problems with the Design Note for oblique angles have been corrected:
It mentioned the Canadian size factor kzcp. This reference has been removed.
It was not updated when it became possible to enter a bearing length and width. It says the bearing width used is b, and suggests you modify output bearing length to compensate for the actual bearing width. These comments have been removed.
The Analysis vs Design table showed kips for the x-direction shear design when it should be psi, and for kip-ft for both moment outputs when it should be psi. This has been corrected.
In the Calculations section of the Additional Data output, the term EIcomp has been changed to EIeff. This confused some users, because although the I-joist composite action is just a 10% approximation, the true calculations using the McCutcheon method use EIeff for the resultant stiffness, and EIcomp is an intermediate calculation.
In a few places, items in the Analysis vs. Design table which were not indented consistently were adjusted.
The term Anal/Des in the Bearing and Reactions table has been replaced with Des. Ratio