Hello,
I am designing a one story building using a pseudo-flexible diaphragm. The lateral force resisting system consists of knee braces at all beam-column connections (which is considered an ordinary moment frame per AISC 341 commentary). I have distributed the forces to the frames based on tributary areas and assigned their percentages in the pseudo-flexible diaphragm properties dialog. My total seismic story shear for this load case is 84.3 kips. When I view the frame story shears and the building story shears, there are multiple shears acting in the +x direction and in the -x direction, the net of which adds up to this total story shear. For instance, the building story shears are shown as +136.02k and -220.31k, which nets to 84.3k. The frame story shears are shown as +19.75k(2)+27.06k(6)-13.74k(2)-90.07k=84.3k. I don't understand why there are story shears acting in the -x direction. I feel like the frame story shears should be 6k(2)+12k(6)=84k (7.1% of the shear to the end frames and 14.2% to the interior frames, as I have the pseudo-flexible diaphragm participation percentages set). Please let me know if there is an obvious cause for the loads to be distributed this way. Thanks!
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