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Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 10.0 and may not reflect current behavior
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:
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.
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.
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.
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.