Residual displacement ratio demand of oscillators representing HSSF-EDBs subjected to near-fault earthquake ground motions

This research investigates the post-earthquake residual displacement ratio demand of high strength steel frames with energy dissipation bays (HSSF-EDBs) under near-fault earthquake ground motions. The study focuses on the ultimate stage of the structure where the HSS frame develops sufficient inelastic deformations. The nonlinear force-displacement behaviour of a HSSF-EDB is idealised by a classical trilinear kinematic model, and the idealised hysteretic behaviour is assigned to oscillators for representing the novel system. To facilitate performance-based seismic design of HSSF-EDBs, the post-earthquake residual displacement demand is related to the yield displacement characterising yielding of energy dissipation bays using the trilinear oscillator analogy, and a non-dimensional residual displacement ratio is proposed. A large number of inelastic spectral analyses of trilinear oscillators covering a reasonable spectrum of hysteretic parameters are performed to quantify the influence of the essential variables on the residual displacement ratio demand of the systems. The results show that the residual displacement ratio of trilinear oscillators representing HSSF-EDBs subjected to near-fault earthquake ground motions is affected by hysteretic parameters in various yielding stages. To offer a practical tool for estimating the residual displacement demand of HSSF-EDBs in the preliminary design phase, empirical formulas quantifying the post-earthquake residual displacement ratio demand of trilinear oscillators are proposed. Finally, the effectiveness of using trilinear oscillators for quantifying post-earthquake residual displacement demand of HSSF-EDBs is emphasised by a comparative study on seismic responses of a prototype HSSF-EDB system and equivalent oscillators under near-fault ground motion samples.