Forces Based On...

Here you choose between using the capacity of the shear wall or the design shear force when determining the forces used for hold-downs and drag strut design.

Note that the forces used to calculate hold-down deflections are always based on applied force rather than shear wall capacity, regardless of this setting.

CSA O86 11.4.4.1 says that hold-downs shall be designed to resist applied force, but according to Structural Commentary 208 associated with A-4.1.8.15.(5), if there is seismic irregularity 4 - In-Plane Discontinuity - Offset from NBC Table 4.1.8.6, then 4.1.8.15.(5) calls for the use of shear wall capacity rather than applied force in the overturning force calculation and for drag strut design. In Shearwalls, such situations occur primarily where vertically discontinuous shear resisting segments have hold-down forces over openings on the level below, but some designers as a general practice used shear wall capacity rather than applied force.

Note that even if shear wall capacity is chosen as the method for shear line forces, in the calculation of the J_hd factor, the hold down forces P_ij’ sed to calculate the R_ij, forces are calculated using the applied force, not the shear wall capacity.