SEISMIC DESIGN AND PERFORMANCE OF CONCRETE MULTI-COLUMN BENTS FOR BRIDGES

This report describes the seismic design and performance of two concrete multi-column bents. The first unit contained a precast fully prestressed cap beam while the second unit was designed with a reinforcement concrete cap beam. A mix of conventional and headed reinforcement and mechanical couplers were used in detailing the cap beam of the second unit. Tests were performed with the objective of examining the most efficient cap beam/column details, which were established in previous joint tests, under the maximum feasible shear demand. Tests results showed that both units produced a satisfactory response when subjected to simulated seismic loading. It was shown that the cap beam prestressing enhanced the performance of the first unit in comparison to the second unit by reducing the deformation and damage of the joints and cap beam flexibility. It was also indicated that the precast construction adopted in the first unit is a viable alternative to the cast-in-place construction for building concrete multi-column bents.