huangyhg

diaphragm question
i have a building with precast concrete walls with metal deck (untopped) roof diaphragm. i have calculated to be flexible.
my questions is that the discussion in the code of rigid/flexible and whether to include torsional effects only appears in the seismic parts of the code. for wind design, can you always consider the diaphragm flexible, and only perform a tributary beam loading analysis to find loads to the shearwalls? and if so, can this be done for the wind loads, even if it would be considered rigid for seismic?
i don't think so. i'm sure others can comment further, but if you have a rigid diaphragm and a center of rigidity that favors one side because of a much longer wall, there will be torsional effects on the building. i don't see how you can just ignore it.
additionally, asce 7 requires the torsional wind load checks (i believe this comes from quartering winds).
what building code are you using? the code should tell you how to apply torsional wind loads. for asce 7-05, see section 6.5.12.3. buildings two stories or less with flexible diaphragms need not consider torsional wind load.

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