Seismic response of building structures with flexible inelastic diaphragm

The inelastic response of one-storey buildings subjected to lateral loads is analysed, making allowance for the real in-plane rigidity and strength of the floors. The structural model consists of a floor diaphragm supported by seven vertical resisting elements with degrading stiffness properties. The elastic design analysis is carried out by modelling the floor diaphragm as a rigid or, alternatively, as a flexible beam. The actual nonlinear response of 240 structures is studied via numerical simulations. Different stiffness and strength distributions in the lateral resisting systems and in the diaphragm are considered. The results of the investigation emphasize the need for an adequate design of the floor diaphragm as a structural element. Also, the results show that the deformability of the diaphragms plays an important role only if the lateral-force resisting system has a markedly non-uniform stiffness distribution; even in such cases, however, adopting the rigid diaphragm hypothesis leads to a more conservative design