Diaphragm Discontinuity Irregularity, ASCE 7-16
Diaphragm discontinuity irregularity is defined to exist where there is a diaphragm with a cut or open area greater than 50% of the gross diaphragm area or a sudden break or variation in stiffness in effective diaphragm stiffness of more than 50%.
In buildings with diaphragm discontinuity irregularity, story slabs are modeled with two-dimensional plate (membrane) or shell finite elements to show that they are able to safely transfer earthquake forces between vertical bearing system elements in their own planes.
In buildings with diaphragm discontinuity, irregularity and/or story floors are not intended to operate as a rigid diaphragm, and in flat slabs, story floors are modeled with two-dimensional finite elements.
