Can additional seismic load cases with 5% eccentricity be avoided as required by IBC code for rigid diaphragm if we use semi-rigid diaphragm in ETABS?
IBC 2006 and ASCE 7-05 have an explicit definition of semi rigid or flexible diaphragm. The concrete slab without any rigid diaphragm option does not fall into category of flexible diaphragm. Therefore accidental eccentricity still needs to be considered for design.
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