Influence of slab spatial composite effect on dynamic behaviour of composite frame structures under earthquake excitation

The slab spatial composite effect plays a significant role in the seismic behaviour of composite frame structures. In this work, the influence of the slab spatial composite effect on the dynamic behaviour of composite frame structures was numerically studied. The self-developed fibre beam–column element program COMPONA-MARC was used to establish models considering and neglecting the slab spatial composite effect for nonlinear static analysis and elastic–plastic time history analysis under various seismic inputs. The maximum roof displacement, inter-storey drift ratio, normalised displacement indices, deformation mechanism, and failure mode were considered to investigate the structural performance. Comparisons indicated that, despite the contributions of the slab spatial composite effect to the structural lateral strength and stiffness, considering this effect may produce more unsafe results. On one hand, it reduces the fundamental natural vibration period and amplifies the effect of seismic excitation; on the other hand, it changes the structural deformation mechanism and failure mode. The influence of slab spatial composite effect on strong column–weak beam mechanism in different storey drift direction angles is also investigated in the paper.