Quantifying the seismic response of structures with flexible diaphragms

SUMMARY Floor diaphragm in‐plane stiffness affects building response to horizontal ground accelerations. This paper describes a series of elastic and inelastic time history analyses of symmetric structures with different deformation types, configurations and heights to quantify these effects. It is shown that displacements of single storey elastically responding structures tend to be most significantly affected by diaphragm flexibility. Analyses of these structures were cross‐verified by a closed‐form mechanics‐based formulation developed to describe the response. Simple relationships were proposed to allow designers to conservatively estimate the increase in peak in‐plane displacement resulting from diaphragm flexibility.