EERI Annual Student Paper Award Confinement of Rectangular Bridge Columns in Moderate Seismic Areas

The work presented in this paper examines the ductility and behavior of rectangular reinforced concrete bridge columns with moderate confinement. Four half-scaled rectangular columns were built and tested. The transverse reinforcement ratios provided in the strong direction of the column specimens corresponded to 46 percent and 60 percent of the minimum lateral reinforcement required by AASHTO for seismic detailing. Each specimen was tested under constant axial load while subjected to quasi-static cyclic lateral loading in the column strong direction. The axial load indexes were 10 percent and 25 percent. The specimens exhibited displacement ductilities ranging between 5 and 7. Based on analytical and experimental results, a simple design equation relating the amount of confinement steel to attainable displacement ductility was developed.