International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran
This paper presents the results of an experimental study which was carried outto identify the vulnerabilities of existing multicolumn bridge bents constructed in Iran and to develop an appropriate retrofit 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 specimensscaled to 30% of prototype dimensions were tested under in-plane cyclic loading condition. One of the specimens simulated as-built condition while the other specimen was retrofitted 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 affected the behavior and energy absorbing capacity of the as-built specimen. Seismic behavior and energy absorbing capacity of the retrofitted specimen improved significantly. The improved behavior of the retrofitted specimen was mainly due to better performance of the joints.