Numerical and analytical investigations on tensile behavior of thick rubber bearings

Abstract

Thick rubber bearings (TRBs) are used for the mitigation of subway-induced vibrations in over-track buildings. TRBs might be loaded in tension in tall buildings, thus their tensile behavior needs to be explored. This paper performs numerical and analytical investigations on the tensile properties of TRBs. First, constitutive laws describing the rubber material under tension beyond cavitation were developed via a two-phase softening model, using the UHYPER user subroutine in ABAQUS. Then, parametric FE analyses were carried out to explore the effects of the shape factors, the thickness of the steel shims and the offset displacement on the tensile properties of TRBs. The numerical results showed that decreasing the first and second shape factors reduced the tensile stiffness of bearings, although the influence of the first shape factor seems marginal, when it is larger than 10. The code specified steel shim thickness (2 mm) seemed adequate, while reducing it to 0.5 mm or 0.2 mm could lead to local buckling of the shims, especially for bearings of lower first shape factors. The reduction of the tensile stiffness and yield force due to shear displacement was quantified. Finally, an analytical model that captures the tensile behavior of the bearings under cyclic loading was proposed and validated on published experimental tests.