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Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 10.2 and may not reflect current behavior.
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.
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.
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.
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.
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.
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)
The following related to the shearwall design strengths when drywall screws are used have been corrected.
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.
For 5/8“ thickness drywall, the values for cooler nails were used instead of drywall screws.
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 correcte d
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.
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.
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.
The program sometimes crashed during seismic load generation when walls are positioned such that they could belong to more than one shearline.