Hysteretic behavior of high damping rubber bearings under multiaxial excitation

The high damping rubber bearing (HDRB) is an advanced seismic isolation component currently used in building structures with excellent energy dissipation capacity. To explore a deeper understanding of the HDRBs' per-formance and effectiveness, a series of six-degree-of-freedom (6DOF) quasi-static tests were designed and con-ducted on three HDRB specimens with different dimensions. The main purposes of the tests are to reveal the hysteresis characteristics of the bearings in the rotational degrees of freedom, and to assess the influence of axial pressure and multiaxial coupling effect on the horizontal performance of the HDRBs. During the tests, the rotational, unidirectional, and bidirectional horizontal (coupled and uncoupled) hysteretic responses were ob-tained. Additionally, several important mechanical parameters are recommended and calculated to evaluate the coupling effect of axial load and rotation on HDRB performance. The results indicate that the axial pressure has a significant impact on the horizontal performance, while the effect of coupling the rotational degrees of freedom is not obvious. In addition, the tests also observed a significant level of stiffness degradation in the horizontal directions after multiple loading cycles.