Visco-elastically connected shear-flexural structure: Elastoplastic seismic response property and a simplified analysis procedure

In a conventional shear-flexural structure, e.g., frame-shear wall building structure, etc., the base shear is mainly resisted by the flexural-type subsystem (shear wall, braced frame, etc.). Post-earthquake observations had proved that the excessive seismic force demand of shear wall or brace could generate irreparable damages. To deal with this issue, a visco-elastically connected shear-flexural (VeSF) structure was developed. The VeSF structure incorporates viscoelastic connectors (VECs) to decouple the flexural-type subsystem and the shear-type subsystem (moment-resisting frame, etc.), which not only mitigates the force demand of the former but also reduces the acceleration response of the latter. The study reported here focuses on the seismic performance of the VeSF structure in the inelastic stage. The most notable features of an inelastic VeSF structure revealed in this study include: 1) the flexural-type subsystem is no longer the primary lateral strength provider, the shear-type subsystem can sustain larger base shear and yield firstly. This could render an enhanced global deformability of the structure, a reduced force demand, and a smaller acceleration response; 2) a more flexible VEC, a larger attributed mass on the shear-type subsystem, and a stiffer flexible-type subsystem would lead to a better seismic performance of the system. As a by-product, a simplified nonlinear equivalent static analysis method is provided to efficiently estimate the inelastic seismic demand of the VeSF structure. The proposal is tailored for non-classically damped structures, for example, those with viscoelastic damper and responding in the elastoplastic range, i.e., the VeSF structure discussed in this paper. By formulating a displacement-conforming, modal-consistent load pattern that explicitly incorporates the non-classic nature of the structural damping, the proposal is proved accurate while being conceptually straightforward and easy-to-implement.