Seismic Strengthening of Reinforced-Concrete Multicolumn Bridge Piers

The analysis, seismic rehabilitation measures, and in-situ performance of a reinforced-concrete (RC) bridge pier subjected to quasi-static loads are presented. The bridge was built in 1963 and was designed for gravity and wind but not seismic loads. The reinforcement details are compared with AASHTO requirements for seismic zones 3 and 4. The bridge pier was rehabilitated with steel dowels connecting the piles to the pile caps and RC grade beam connecting the three pile caps; carbon Fiber-Reinforced-Polymer (FRP) composite jackets were used to rehabilitate the columns, cap beam, and T-joints. An analytical model is presented that includes the effects of soil-pile-structure interaction and the seismic rehabilitation measures. Critical events in the experimental performance of the bridge pier are identified. Comparisons are made between the pier's performance and that of other piers tested in situ at the same site that were rehabilitated with incremental measures.