Seismic Performance of a Highway Bridge with Different Modeling Techniques for Laminated Rubber Bearings at a Low Temperature

The current study is devoted towards evaluating the effectiveness of modeling of natural rubber bearings (RBs) and lead rubber bearings (LRBs) on seismic responses of a highway bridge by conducting nonlinear dynamic analysis for six distinct ground motions of level-2 earthquake applied in the longitudinal direction. Three analytical models of isolation bearings are considered for comparison: the conventional design models including the equivalent linear model and the bilinear model, a rate-dependent rheology model, and a proposed simplified model. The novelty of the proposed simplified model is to reproduce the nonlinear elasto-plastic behavior along with strain hardening at high strain levels. Model parameters for the isolation bearings are evaluated from experimental results at low temperature (-20°C). A numerical algorithm for solving the first order governing differential equation of the rheology model has been developed to implement into nonlinear dynamic analysis software. The dynamic responses of the isolation bearings and the rotation responses of the plastic hinge in concrete piers are compared for different modeling. The effect of modeling the isolation bearings at low temperature is significantly observed in the responses indicating that a careful selection of isolation bearing's model is imperative for seismic design of an isolated bridge system.