Document Type : Structural Earthquake Engineering
Kansas State University
This paper presents the results of an experimental study conducted to assess the seismic response of the commonly used multicolumn bridge bents constructed in Iran. Observing the real performance of the bent, capturing undesirable failure modes, and verifying current code requirements are the main goals of this study. A 30% scaled specimen was designed, constructed and tested under simulated earthquake loads. The results indicate that the joint failure and slippage of longitudinal column reinforcement within the joints are the predominant failure modes under lateral cyclic loading. Such failure modes adversely affect the energy-absorbing capacity by a significantly pinched hysteresis response. Slippage of the column's longitudinal bar is the main contributing factor for the pinched hysteresis response. Based on the test results, AASHTO requirements for development length of the column's longitudinal bars inside the cap-beam is unnecessarily long, and it can be reduced considering the confinement effects of transverse reinforcement. Test results also indicate that the displacement capacity of bridge bents calculated by the AASHTO approximate equation may be unconservative.