Seismic assessment of bridge structures isolated by a shape memory alloy/rubber-basedisolation system

Abstract

This paper explores the effectiveness of shape memory alloy (SMA)/rubber-based isolationsystems for seismic protection of bridges against near-field earthquakes by performing asensitivity analysis. The isolation system considered in this study consists of a laminatedrubber bearing, which provides lateral flexibility while supplying high vertical load-carryingcapacity, and an auxiliary device made of multiple loops of SMA wires. The SMA deviceoffers additional energy dissipating and re-centering capability. A three-span continuousbridge is modeled with the SMA/rubber-based (SRB) isolation system. Numericalsimulations of the bridge are conducted for various near-field ground motions thatare spectrally matched to a target design spectrum. The normalized forwardtransformation strength, forward transformation displacement and pre-strain level ofthe SMA device, ambient temperature and the lateral stiffness of the rubberbearings are selected as parameters of the sensitivity study. The variation of theseismic response of the bridge with the considered parameters is assessed. Also,the performance of the SRB isolation system with optimal design parametersis compared with an SMA-based sliding isolation system. The results indicatethat the SRB isolation system can successfully reduce the seismic response ofhighway bridges; however, a smart isolation system that combines sliding bearingstogether with an SMA device is more efficient than the SRB isolation system.