Hysteretic Restoring Force Characteristics of High Damping Rubber Bearings Under High Compressive Stress

Hysteretic restoring force characteristics — shear stiffness, equivalent damping ratio, and ultimate properties — of seismic isolation bearings are significantly affected by compressive stress. In this study, dependence of shear properties of high-damping rubber bearings (HDR) on the compressive stress σ and secondary shape factor S₂ was studied by dynamic loading test with scaled-model and static loading test with full-scale isolators. The results highlighted the high compressive stress dependency on restoring force characteristics of HDR with the isolator of relatively small S₂. It is concluded that large S₂ is desired when isolators are designed for high compressive stress. The applicability of HDR under high compressive stress was experimentally verified.