Evaluation of Retrofit of Beam-Column T-Joints in Older Reinforced Concrete Bridge Structures

Experimental tests and analyses investigated the seismic behavior of reinforced concrete beam-column T-joints. The test specimens were representative of interior beam-column joints in multicolumn bridge frames constructed in California in the 1950s and 1960s. Three one-third scale models were tested, one representing the as-built joint and two representing retrofit joints. The as-built specimen had relatively little ductility capacity, whereas the retrofitted specimens exhibited improved performance. The nominal joint stress state, joint force-transfer mechanisms, and bond stress characteristics were investigated as a means of assessing joint behavior. This study clarifies the seismic behavior of lightly reinforced bridge T-joints and verifies a design procedure for retrofitting these joints.