Seismic Investigation of Steel Pile Bents: II. Retrofit and Vulnerability Analysis

This paper is the second of a two-part study on the seismic vulnerability of deck bridges supported on steel pile bents. A conceptual elastic cap/elasto-plastic steel pile retrofit strategy is proposed in this part with the aim of strengthening the connection and ensuring plastification takes place only in the steel pile. An experimental program was carried out to assess the retrofit strategy. On the basis of the experimental results for existing as well as retrofitted connections, a seismic vulnerability analysis for bridges supported by steel pile bents was performed. Fragility curves for such structures were developed using a simplified fundamental mechanics-based approach. The study showed that the retrofitted connections exhibited superior energy absorptions with respect to the existing connections. Fragility curves also demonstrated the effectiveness of the retrofit strategy proposed.