Post-Earthquake Traffic Capacity of Modern Bridges in California

摘要

Evaluation of the capacity of a bridge to carry self-weight and traffic loads after an earthquake is essential for a safe and timely re-opening of the bridge. In California, modern highway bridges designed using the Caltrans Seismic Design Criteria are expected to maintain at minimum a gravity load carrying capacity during both frequent and extreme seismic events. However, no validated, quantitative guidelines for estimating the remaining load carrying capacity of such bridges after an earthquake event exist today. In this study, experimental and analytical methods were combined to evaluate the post earthquake traffic load carrying capacity of a modern California highway overpass bridge. An experimental study on models of circular reinforced concrete bridge columns was performed to investigate the relationship between earthquake-induced damage in bridge columns and the capacity of the columns to carry axial load in a damaged condition. The test results were then used to calibrate a finite element model of a bridge column. This bridge column model was incorporated into a hybrid model of a typical California overpass bridge and tested using the hybrid simulation technique. The finite element model of the typical California overpass bridge was validated using the data from hybrid simulations. The validated model of the typical bridge was used to evaluate its post-earthquake truck load capacity in an extensive parametric study that examined the effects of different ground motions and bridge modeling parameters such as the boundary conditions imposed by the bridge abutments, the location of the truck on the bridge, and the amount of bridge column residual drift.