Effect of Pier and Deck Flexibility on the Behavior of Isolated Integral Bridge Under Far and Near-Fault Earthquake

The effect of the flexibility of the bridge on the seismic response of the base isolation of the integral bridge is studied. For the study, flexibility of deck and pier were considered separately. The pier height and length of the middle span were varied to consider flexibility of pier and deck, respectively. For the seismic analysis, suit of both far and near-fault earthquakes was used. Nonlinear dynamic analysis was conducted using one-component and two-component time histories of both far-fault and near-fault earthquakes. For the earthquake loading on the bridges, the direction of major component of the time history was aligned along the length of the bridge. Various response parameters were considered which include the bending moment (BM) in the longitudinal girder about major axis, BM of in the pier about major and minor axis, and displacement of the deck in longitudinal direction. As the study is intended to investigate the effect of flexibility on the isolation of the integral bridge, the responses of isolated bridges were normalized with the corresponding fixed base bridges. From the results, it was noted that pier flexibility affects greatly the isolation effect.