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Modeling and seismic response comparison of california high-speed rail prototype bridge with and without seismic isolation

The appropriateness of seismic isolation in California High-Speed Rail (CHSR) bridge structures with overlying ballastless track system in high seismic areas is a serious concern to structural engineers. In order to explore and identify the positive and negative effects of seismic isolation on CHSR bridge systems, a three-dimensional (3D) detailed nonlinear finite element (FE) model of a prototype bridge, including soil-pile-structure interaction and rail-structure interaction, is developed in OpenSees. The seismic response of the isolated bridge (IB) is compared with that of the corresponding non-isolated bridge (NIB) in both a deterministic and probabilistic sense. At the deterministic level, nonlinear time history analysis results are compared for the IB and NIB subjected to two bi-directional horizontal ground motion records, which are selected and scaled to be hazard-consistent for both the IB and NIB. The probabilistic performance of the bridge structures is assessed within the well-established performance-based earthquake engineering (PBEE) methodology, focusing on probabilistic seismic demand hazard analysis which accounts for the uncertainty in seismic loading at the assumed site of the prototype bridge. Conclusions are drawn on the beneficial and detrimental effects of seismic isolation on the seismic performance of the CHSR prototype bridge considered. The potential adoption of seismic isolation for CHSR bridges is promising based on the results obtained in this study.

Author(s):

Yong Li    
University of California, San Diego
United States

Joel Conte    
UCSD
United States