Single and combined use of friction-damped and base-isolated systems in ordinary buildings

Abstract

This study addresses the nonlinear seismic responses of ordinary moment frame building upgraded with a series of passive protective systems. To this, friction damper (FD) as an energy dissipation device and lead rubber bearing (LRB), friction pendulum bearing (FPB), and high damping rubber bearing (HDRB) as base isolators were considered. The effectiveness of the isolation systems together with the dampers was investigated comparatively. For this purpose, eight different cases were taken into account. The first case contains a five storey steel ordinary moment frame considered as fixed-base (FB), the other four cases are the single use of FD, LRB, FPB, and HDRB in such frame, and the last three cases include the upgrading of the frame with the combination of FD with each of the base isolation systems. They are modelled using a finite element program, and evaluated by the nonlinear time history analyses in which seven ground motion records were adopted. The seismic performance of the passive protective systems was evaluated by the engineering demand parameters such as storey displacement, bearing displacement, relative displacement, roof drift ratio, interstorey-drift ratio, absolute acceleration, base shear, base moment, hysteretic curve, and energy dissipation. One of the main outcomes of this study was that single protective system could not always satisfy fully operational performance level, while the combined systems of the base isolation with friction damper effectively achieved for the case study frame. Furthermore, the results showed that the combined systems were capable of limiting the inter-storey drift without increasing the absolute accelerations.