Hysteretic restoring force model of high damping rubber bearings including thermo-mechanical coupled effect

Abstract

In the application of High Damping Rubber (HDR) bearings as seismic isolation devices for bridges in cold regions, there are concerns about the low temperature effect on the hysteresis performance of HDR bearings and the resulting deterioration in bridge performance under strong ground motions. The stiffness and damping ratio of the HDR bearing significantly increase at lower ambient temperatures, and the stiffness reduces as the inner temperature of the bearing increases due to the self-heating of rubber material under repeated cyclic loading, resulting in a complicated thermo-mechanical coupled hysteresis behavior which is not expressed by the currently available restoring force models of HDR bearings. In this study, a simplified thermo-mechanical coupled hysteretic restoring force model of HDR bearings is newly developed. The model parameters are identified from the shear strain–stress curves of HDR bearings obtained in quasi-static cyclic loading tests at three different ambient temperatures. Accuracy of the improved model is verified by comparing the numerical result of seismic response analysis of a bridge model using the proposed restoring force model with the result of hybrid simulation of the same bridge model including the HDR bearing loading test under low-temperature conditions.