Seismic Performance Evaluation of Lead High-Damping Rubber Bearings Tested by Real-Time Hybrid Simulations at Low Temperatures

Lead high-damping rubber (LHDR) bearings, composed of high-damping rubber and lead core, are effective isolation devices that address increased seismic demands. The temperature effect on the behavior of LHDR bearings is significant, leading to increased initial stiffness at low temperatures. This poses challenges to the seismic performance of isolated bridges using these bearings. However, most research on the temperature effect of bearings has been confined to low-rate cyclic or seismic loading, making it difficult to reflect the response of isolated bridges under realistic ground motions. In this paper, the real-time hybrid simulation (HS) was conducted to investigate the seismic performance of LHDR bearings, accounting for the temperature effect. Cyclic loading (CL), with and without cooling intervals, was applied at -20 degrees C, 0 degrees C, and 23 degrees C to evaluate the hysteretic behavior of the bearings. Real-time and pseudo-dynamic HSs were then conducted using 1/6 scaled specimens, representing the large-scale models in the numerical simulation, to investigate the seismic performance of the bearings. The scragging effect and rate dependence were considered and discussed in the CL and HS. Finally, a modified thermo-coupled restoring force model for LHDR bearings was proposed, effectively capturing their hysteretic behavior and temperature history.