|
|
|
|
|
Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 10.0 and may not reflect current behavior
The program now calculates the total diaphragm design force Fpx from equation 12.10-1 in 12.10.1.1 on each floor in each direction. This force is output to aid you in manually doing diaphragm design calculations (Shearwalls does not model or design diaphragms), and is the force used for the 25% increase in drag strut forces required by 12.3.3.4 for irregular structures.
The Site Information input that was previously called Irregular Structure, which was used for redundancy factor calculations, has now been replaced by two settings,
Horizontal irregularity or in-plane vertical discontinuity irregularity.
Other vertical irregularity
The first of these settings is used to trigger the 25% increase in drag strut forces required by 12.3.3.4. If either is selected, then the building is considered irregular for redundancy factor purposes. These inputs are echoed in the Site information output in an abbreviated form.
If the irregularity checkbox is checked, and the other conditions of 12.3.3.4 are met (Seismic Design Category D-F), then the program determines the shearline forces that are derived from the diaphragm force by multiplying the shearline design forces that were derived from Vx from 12.8-13 by the ratio between the diaphragm force Fpx from 12.10-1 and Vx . The program then uses the worst of the forces derived from 1.25 Fpx and from Vx to calculate drag strut forces along the shearline. Note that the force from 1.25 Fpx will govern only on the top level of the structure, and in some cases on the level immediately below, because it does not accumulate from level to level as Vx does.
The diaphragm force Fpx has been added to the Seismic Information table in both directions and in both levels. This is an unfactored (strength-level) force.
A note beneath the table that has been added explaining that story shear does not include user-applied seismic forces also mentions the same thing about the diaphragm force.
When the seismic design category is C-F, the legend to the Drag Strut table explains that the shearline force is derived from the greater of Fpx with 25% irregularity increase and Vx
The legend also now mentions that the shearline force is factored by the redundancy factor rho.