Simplified estimation method of inelastic seismic demands of buildings with seesaw system using fluid viscous dampers

Abstract

In this paper, the simplified estimation method, which is useful for structural reliability assessment and design, is proposed to estimate the inelastic seismic demands of buildings with a seesaw energy dissipation system (SEDS) using fluid viscous dampers (FVDs). The proposed method considers the inelastic spectral displacement and the inelastic first mode vector. In this method, the inelastic spectral displacement is estimated using a single-degree-of-freedom (SDOF) system equivalent to a multi-story frame with an SEDS using FVDs, and the inelastic first mode vector is estimated using a pattern of floor displacements obtained from nonlinear static pushover analysis (NSPA) of a multi-story frame, which considers the behavior of velocity-dependent dampers. Nonlinear time history analysis (NTHA) was performed on series of three- and six-story steel moment-resisting frames with an SEDS using FVDs and a corresponding equivalent SDOF system model. Also, NSPA was performed on an inelastic multi-story frame with an additional spring, which considers the viscous behavior of velocity-dependent dampers. Comparing the results of the peak inter-story drift ratio estimated by the proposed method with those computed via NTHA, the proposed method has sufficient accuracy for the evaluation of seismic demands.