Seismic retrofit of a typical reinforced concrete bridge bent in Iran

This paper presents the results of an experimental study which was carried out to identify the vulnerabilities of existing multicolumn bridge bents constructed in Iran and to develop an appropriate retrot measure to alleviate such vulnerabilities. In this study a three column reinforced concrete bridge bent, which was designed for gravity load with inadequate seismic detailing, is considered. Two identical specimens scaled to 30% of prototype dimensions were tested under in-plane cyclic loading condition. One of the specimens simulated the as-built condition while the other specimen was retrotted by external prestressing along the cap beam as well as transverse prestressing of an exterior joint. The test results on the as-built specimen indicate that joint shear distress and bond failure of longitudinal column reinforcement within the joints are the predominant failure modes. Such failure modes adversely aected the behavior and energy absorbing capacity of the as-built specimen. Seismic behavior and energy absorbing capacity of the retrotted specimen improved signicantly. The improved behavior of the retrotted specimen was mainly due to better performance of the joints.