Assessment and Retrofit of a Reinforced Concrete Bridge Pier for Seismic Resistance

Typical structural deficiencies in some reinforced concrete bridges designed for seismic resistance before current seismic codes were introduced are briefly outlined. Results of simulated seismic load tests conducted on the critical region of a reinforced concrete bridge pier designed in New Zealand in 1936 are presented. The tests involved the application of compressive axial loading and quasi-static cyclic lateral loading to a full-scale subassemblage representing the column-cap beam region of the as-built pier. Subsequent loading tests were conducted on the pier retrofitted mainly by the addition of steel plates welded to the ends of the plain round longitudinal bars to improve anchorage. The improved bar anchorage enabled the pier to develop its full theoretical flexural strength, but the considerable loss of stiffness due to bond degradation which occurred in the initial test on the as-built pier was not restored.