Seismic design and experimental verification of concrete multiple column bridge bents

Following widespread bridge damage in recent California earthquakes, a sign ificant amount of research has been carried out to improve seismic performa nce of bridge structures. Compiling recent advances, two large-scale concre te multiple-column bridge bents were designed and subjected to simulated ea rthquake loading at the University of California, San Diego (UCSD). In addi tion to serving as proof-test specimens, these bridge bents facilitated inv estigation of improved cap beam-to-column joint reinforcement details to mi nimize construction difficulties. The design of the joints in the first tes t unit was simplified by using prestressing in the bent cap and examining t he force transfer across the joint, which also enabled introduction of prec ast construction for concrete multiple column bents. In the second test uni t, joint reinforcement was minimized by utilizing efficient joint force tra nsfer models and special reinforcement products. Design details, seismic pe rformance, and some test results of the multiple column bents are presented in this paper.