Hysteretic behaviour of lightly reinforced concrete exterior beam-to-column joint sub-assemblages

Reinforced concrete frames are designed to withstand severe earthquakes by developing flexural plastic hinges in beams, away from the beam-to-column joint. To preclude shear and bond failures, additional shear reinforcement and anchorage lengths are advocated leading to congestion in the joint region. To clarify the effect of joint detailing on the seismic performance of lightly reinforced concrete frames, an experimental study was undertaken. The parameters studied were the effect of joint rotation, column axial load, cross-reinforcement in the joint and percentage of longitudinal reinforcement in the beam. The test results and qualitative evaluations are reported. It was found that joint rotation and axial load in the column are beneficial. The cross-reinforcement in the joint reduced the damage in the joint region but had an adverse effect on the cyclic performance.