As per SDPWS 4.3.6.1.2 Eqn. 4.3-7 , the overturning component of the tensile hold-down force and the compression force at the other end is calculated by
T = C = Vh/ beff
= vh x b/beff
where
V is the ASD-factored shear force on the wall segment,
v is the unit shear force on the wall segment.
h is the height of the wall. In the Hold-down settings, you can decide whether the height includes the height of the diaphragm floor joist as well. The SDPWS equation indicates that this distance is not included, but this creates gaps in the static analysis of multi-level structure.
Refer to the discussion in the Holddown forces topic for wall heights at gable ends.
beff is the length of the wall between the hold-down tension force location at one end and the compression force in the end studs at the other end. The tension force is located at the inner face of the end studs plus the hold-down anchor bolt center line location for the hold-down model from the hold-down database. The compression force is assumed to be located at the center of the end stud pack. However, in the Hold-down settings, you can choose to override this calculation with a fixed distance from each end for all hold-down and compression forces in the structure.
b is the total length of the wall segment, including end studs.
This calculation applies to segmented and FTAO walls. A different calculation is used for perforated walls; see Perforated Shear Wall Forces.
