Seismic Analysis of Non-Isolated and Isolated Bridges

Abstract

Bridge modal of 3span of length 32m and width of 9.5mis considered for the present study. 3 models are used in this study one is non-isolated bridge modal and two models of base isolated bridges with different lead rubber bearings. Isolators are designed by considering suitable soil type and site conditions. And the properties of isolators are introduced between super structure and sub structure. Influence of the base isolator is studied. All three models are analyzed for seismic response spectrum method in both X and Y directions. The influence of the lead rubber bearing in the dynamic behavior of the bridge shows an extended time period, reduction in deck displacement and decreased deck acceleration in both isolated bridge models. Considerable difference is not observed in both isolated bridge models. Results of the analysis shows that certain amount of seismic energy is decimated by lead rubber bearing between sub structure and super structure.