Fundamentals of Shape Memory Alloy–Rubber Bearing Seismic Design and Assessment

In this study, a shape memory alloy (SMA) and general rubber bearing are used to develop a novel SMA–rubber bearing combination. This bearing is then used to develop a smart isolation system that can achieve vibration control in a bridge structure during earthquakes. The system design is based on a martensitic NiTi SMA (atom fraction of Ni=51%) with a production diameter of 1.0 mm. The damping provided by the NiTi alloy is frequency dependent and increases with prestrain and amplitude. To investigate the basic mechanical behavior of the designed SMA-rubber bearing, three-dimensional finite-element models were constructed and the optimized parameters of the bearing were analyzed to investigate their effects on mechanical behavior. To assess the isolation effectiveness of the bearing, a simply supported beam bridge with different bearings was investigated under various earthquake excitations to compare the effects of vibration isolation. Through optimization analysis, design parameters for prestrain (3.0–4.0%), α value (18–25°), and Shore hardness were obtained. An application analysis showed that the proposed bearings limit the relative displacement of a bridge deck effectively under strong ground motions and that they almost completely recover their original shape.