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Highly Variable Force Distribution
Because deflection is highly dependent on the aspect ratio of the wall segment and on the hold-down forces and hold-down devices employed at each segment, deflection can be highly variable along a line, and segments that are quite similar in size and construction can draw markedly different forces, and some segments can draw no force at all. This is particularly true for lightly loaded shear lines for which constant components in the deflection equation are dominant when compared to the components which depend on the shear force v. In this case the procedure places most or all of the shear force v on segments that may be only slightly different than others to make up the difference in the effect of segment aspect ratio and the constant components.
Zero Force
If a wall segment draws a load of less than 0.1 lb, the program assigns zero load to that segment and equalizes the deflection on the remaining segments. The segment that gets zero force is treated as an opening or a non-shearwall for the purpose of shear wall design and hold-down and drag strut calculations. This is shown graphically in the image below, the blue curves represent force-displacement profiles for wall segments, and the red line represents a solution that equalizes deflection. (The curves are extended into the negative quadrant to ensure a solution).
The solution arrives at negative deflection for one of the segments, so we remove that segment and try again:
