Experimental and numerical investigations on mechanical properties of high-damping rubber bearings under large strain loading

Abstract

Seismic isolation technology typically protects superstructures by incorporating isolation bearings between the superstructure and the foundation. The isolation system extends the natural period of the structure and provides additional damping, effectively dissipating earthquake-induced energy during strong earthquakes. Among the commonly used bearings, high-damping rubber bearings (HDRBs) have emerged as a preferred solution due to the inherent energy dissipation capability. However, during near-fault strong earthquakes, isolation bearings are prone to experiencing large strains. Previous studies have paid little attention to the large strain responses of HDRBs under various loading conditions, which significantly differ from their hysteresis properties under moderate shear strain loading. To address this gap, this study experimentally and numerically investigated the hysteretic responses of four full-scale HDRBs under large cyclic strains of up to 400 %. Test results indicate that the mechanical properties of HDRBs are significantly influenced by strain levels and loading protocols. The HDRBs exhibit pronounced nonlinearity in their shear force–strain relationships. Notably, as shear strain exceeds 200 %, the HDRBs demonstrate significant nonlinear hardening, strength degradation, and unloading effects. The hardening stiffness of the HDRBs is considerably higher than the post-yield stiffness. Furthermore, HDRBs show substantial variations in peak strength and degradation characteristics under different loading protocols. A numerical strategy was also developed to further explore the deformation mechanisms of the HDRBs under large strain loading conditions.