Shape memory alloy-spring damper for seismic control and its application to bridge with laminated rubber bearings

Abstract

This study introduces a shape memory alloy (SMA)-spring damper which is composed of SMA bars and elastic springs arranged in perpendicular. The damper depicts a curved flag-shape hysteretic behavior that is endowed with self-centering capacities and large deformation capabilities but uses reduced amount of SMA material. A design procedure is proposed to apply the SMA-spring damper to the bridge with laminated rubber bearings which would slide under seismic excitations. Analytical results validate the effectiveness of SMA-spring dampers in seismic control of the bridge: (1) The damper provides trivial stiffness to the bridge at small displacement, and the isolation efficiency of the bridge is maintained; (2) large horizontal force is provided for the structures at large deformation of the bearings, which alleviates the excessive displacement of bearings and prevents span collapse; and (3) the damper helps recenter the bearings and reduce the residual displacement of the bridge.