Nonlinear Viscosity Law in Finite-Element Analysis of High Damping Rubber Bearings and Expansion Joints

A simple computational strategy for finite-element implementation of a finite-strain viscohyperelasticity model for rubber-like materials was developed. The constitutive model has had a strong physical significance because of the explicit consideration of the nonlinear dependence of viscosity through internal variables (e.g., past maximum overstress and current deformation). To simulate the stress-strain response for particular one-dimensional boundary value problems, a scheme for solving the first-order differential equation representing the viscosity-induced strain-rate effect of rubber was proposed. The scheme was successful in reproducing experimental results obtained from high-damping rubber specimens. In addition, the wider applicability of the proposed strategy in simulation was tested by verifying the numerical results with independent experiments on full-scale high-damping rubber bearings with different geometries and loading rates. The effect of shape factor on bearing responses was examined through numerical examples obtained from different finite-element models subjected to the same load and loading rate. Finally, the proposed computational strategy was applied to locate the regions of stress concentrations in steel plate laminated rubber expansion joints used widely to transfer reactions at central-hinge locations on balanced cantilever highway bridges. (C) 2014 American Society of Civil Engineers.