Efficient analysis models for multistory building structures with In-plane floor slab flexibility

Abstract

The rigid floor diaphragm assumption is widely used for the analysis of multistory building structures because of the simplicity in the analysis procedure. But application of such assumption to the seismic analysis of building structures may be not valid in many cases. To investigate the effect of in-plane floor slab flexibility efficiently, in this study, analytical models for multistory building structures such as those with rectangular plans, setback or wings are proposed. Since a building structure with wings is regarded as a combination of wing structures and their junction, the proposed analytical model is easily applicable to building structures with plans in the shape of letters Y, U, H, etc. The accuracy and computational efficiency of the proposed analytical models at examined by comparison of analysis results obtained from the proposed models and three-dimensional finite element models. The effect of in-plane floor slab flexibility on the seismic behavior of building structures according to the variation of the number of bays and stories and the difference in stiffness among lateral-load-resisting elements is investigated. The in-plane floor slab flexibility may bring about longer vibration periods that result in the reduced seismic base shear. However, some part of the structure may be subjected to increased stress due to shear force redistribution caused by the large in-plane deformation of floor slabs. This phenomenon is more significant when the aspect ratio of a floor slab system is high or the number of stories is not great. It is desirable to include the in-plane deformation of floor slabs in the seismic analysis of building structures for economical and safe design when the in-plane deformation of floor slabs is expected to be large.