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Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 10.1 and may not reflect current program behaviour.
The following problems when using the CSA O86-09 design code is set, pertaining to the design of shearwalls using power driven nails according to Note 5 of Table 9.5.1A, which refers to the procedure in A9.5.1, were corrected.
The program was using the capacity corresponding to the standard nail in Table 9.5.1A smaller than the power-driven nail, then increasing the capacity listed in table by the square of the ratio of the power nail to the standard nail. However, A.9.5.1 says to use the standard nail size larger than the power nail size and decrease the capacity by the square of the ratio.
This created small errors in capacity for nails greater than 2.84 mm in diameter, the smallest standard nail diameter in table 9.5.1, and for known sheathing thickness, power-driven nails less than 2.84 mm diameter had zero capacity when they should have had a factored capacity.
The program was allowing nail sizes less than 80% of the smallest size listed in Table 9.5.1 (2.84 mm) and calculating nail size adjustment factors from A9.5.1 based on that, even though A9.5.1.1 limits the allowable nails to those within 80% of the sizes listed in 9.5.1. These factors were only applied for unknown sheathing thickness due to item a), above.
Note that the smallest standard nail size in Shearwalls is 2.87 mm, corresponding to the ASTM F1667 wire gauge size corresponding to 2.84 in the obsolete CSA O86 B111 nail standard. The program however limits nails to at least 80% of 2.84, or 2.272 mm.
The following changes were made to the detection of Structural Irregularity 2 - Weight (mass) in NBC Table 4.1.8.6.
The program was using the definition of a "storey", italicized in Table 4.1.8.6 to indicate that is from the definitions in Division A, 1.4.1.2, as the distance from the top of one floor to the top of the floor above it. The roof was considered a separate storey because of the line in 4.1.8.6 saying "A roof that is lighter than the floor below need not be considered. ", implying a heavier roof need be considered as a separate storey.
However, we have received advice that the same definition of building levels used for vertical seismic force distribution should be used, that is, from the middle of the wall on one level to the middle of the walls on the level above. In this model, a roof is considered part of the upper level.
The reason for this re-evaluation is that the purpose of the weight irregularity is to make sure the structure behaves as assumed in the Equivalent Static Procedure, which is based on the first (near-linear) mode of the "lumped mass" dynamic response model that is used for vertical seismic load distribution. The linear mode assumption requires a relatively uniform mass distribution amongst the storeys.
Furthermore, an identical irregularity provision in the USA ASCE 7 Table 12.3-2, Irregularity 2, uses the term "effective mass", rather than the weight of a storey.
The interpretation of a storey as per the literal NBC definition caused problems with the following situations, that are eliminated by using the vertical seismic force distribution definition:
The storey weight for the roof did not include 25% of the snow load which is used in seismic load generation, but it should have been included, as the irregularity description in Table 4.1.8.6 includes the symbol Wi, which is defined in NBC 4.1.8.2 as a portion of W, and in the definition of W, it includes 25% of the snow load.
Therefore, the snow load is now included in the weight of the uppermost level as defined in item (a) above.
The program reported a torsional irregularity for all or most structures when only seismic loads were applied to the structure, regardless of whether this torsional irregularity existed. As a result, the Design Summary indicated that due to an irregularity, seismic design was not valid, and the Irregularities table in the Design Summary showed the irregularity 7 failing in one direction, and a red note at the top saying the Equivalent Static method is not available for that reason. This has been corrected.
Wall parameters related to hold-downs were being included in the definition of standard walls, although they are not part of the material specification intended to be part of a Standard wall: As a result, the following would occur if these were changed for a wall:
The following data were not available for selection in Standard Wall mode, but were being treated as Standard Wall parameters:
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.
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:
If there is another block that a roof could join to, the Joined selection was sometimes disabled so the operation was impossible.
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.
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.
The legend entry GU - Gypsum underlay thickness is now displayed in Sheathing Materials table in the Design Results when CSA O86-14/NBC 2015 is selected. Previously it displayed only when CSA O86-09/NBC 2010 was selected.
In the line saying Linearized 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. The deflection equation is irrelevant if there is no deflection analysis, and the Include deflection analysis setting was not previously reported in the output.