Seismic performance upgrading of bridges using superelastic pendulum isolators with variable stiffness considering temperature effects

Abstract

To enhance the seismic resilience of bridges, this study proposes a novel superelastic pendulum isolator with variable stiffness (SPIVS) equipped with copper-based shape memory alloy (CuSMA) against near-fault earthquakes. The sensitivity of the novel SPIVS to outside temperature effects is considered. A three-span bridge equipped with the proposed SPIVSs incorporating the CuSMA devices is modeled in OpenSees software. A fractional factor based design method is proposed to optimize the parameters of the SPIVS system. The seismic performance of the novel SPIVSs for bridges is assessed considering outside temperature effects by conducting case studies. Results show that the optimum parameters of the novel SPIVS system for various cases are obtained by the proposed method. The novel SPIVS using CuSMA devices can dually control the girder peak displacement and isolator residual deformation for various ambient temperatures. The base force increment of piers is also controlled within 10% to limit the seismic demand. The feasibility and effectiveness of the novel SPIVS system using CuSMA devices, in terms of re-centering and damping capacities for bridge response control at different outside temperatures, are discussed and demonstrated by various cases.