Response of Bridges Isolated by Shape Memory–Alloy Rubber Bearing

Abstract

The present paper deals with optimum performance of the shape memory–alloy-based rubber bearing (SMARB) compared with the conventionally adopted lead rubber bearing (LRB) for isolating the bridge deck against a random earthquake. Specifically, a systematic study on the optimum performance of SMARB is conducted and compared with the LRB to minimize the acceleration of the isolated deck subjected to a stochastic earthquake by addressing the limitation on the excessive isolator displacements. The optimal characteristic strength of the bearing and respective responses are obtained by solving a bi-objective optimization problem. The responses required for this are obtained by nonlinear random vibration analysis via stochastic linearization of the cyclic nonlinear force-deformation behavior of the shape memory?alloy restrainers. The robustness of the improved performances of the SMARB was studied through extensive parametric studies with respect to the variation of the system parameters and the scenario of earthquake loading. The results clearly indicate facilitation of the trade-off among the isolation efficiency and the bearing displacement in the SMARB over the conventional LRB. The approximate closed-form expressions for obtaining the proposed optimal parameters and system responses might be helpful in establishing an initial design.