Experimental and Numerical Studies on Thick Rubber Bearings under Uniaxial and Offset Tensile Loading

Thick rubber bearings (TRBs) have been proven to be effective in mitigating horizontal shaking induced by earthquakes as well as railway-induced vertical vibration. During earthquake excitations, TRBs might be subjected to tension, which should be carefully assessed during design. This paper presents experimental and numerical studies on the behavior of TRBs under tensile loading. Four full-scale thick natural rubber bearing (TNRB) and lead thick rubber bearing (LTRB) specimens were designed and tested under tension, with and without lateral offset. The test results showed that increasing the applied lateral offset decreased the tensile stress and stiffness of the TNRBs, while the LTRBs did not exhibit any reduction. In addition, the test results were compared with design specifications in current codes for conventional rubber bearings. Finally, finite element (FE) models of TRBs were built and validated against the results of uniaxial and offset tensile experiments, and the cavitation of rubber was modeled via a two-phase model. To further estimate the damage due to previous tensile loading, damage variables under cyclic tensile loading were also taken into account. The experimental and numerical results showed that the lead core only slightly increased the initial tensile stiffness of the bearing under uniaxial testing, while it had a significant influence on the tensile properties of the LTRBs under offset displacement.