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This setting affects the distribution of shear forces to each wall segment within a shear line when the setting for distributing forces to the shear lines is via deflection-based stiffness. However, it applies to both the rigid and the flexible diaphragm methods of distributing shear force to the shear lines.
If the Use shear wall deflection to calculate rigidity box is selected and the Distribute forces to wall segments based on rigidity box is checked, and the then the program will attempt through an iterative procedure to equalize deflections on the shear line by redistributing the shear force v to the segments until the deflections calculated with CSA O86 11.7.1.2 are the same for all segments. Refer to Distribution to Segments within Shear Line for more information.
If this box is not checked, the program distributes forces to the shear wall segments proportionally to the capacity of the wall.
Note that the legend to CSA O86 Figure 11.7 indicates that relative resistance of the shear wall segments is to be used to determine the distribution of forces along a shear line. However, according to CWC Wood Design Manual,
The most rigorous approach is to distribute the forces based on the relative stiffness of each segment using the shear wall deflection equations to determine the stiffness of each segment.
The deflection-based method can greatly increase design processing time due to the iterative procedures, and can result in many low-stiffness segments or sides of walls taking zero load, especially on lightly loaded shear lines.