Effects of beam-column depth ratio on seismic behaviour of non-seismic detailed reinforced concrete beam-column joints

Four reinforced concrete exterior beam-column joints with open anchorage beam reinforcement, which are manufactured to simulate those in existing reinforced concrete framed buildings, are tested under reversed cyclic loads simulating earthquake excitation. The particular emphasis of this project is given to the effects of the beam-column depth ratio and the stirrup ratio in joints on the shear strength and seismic behaviour of the exterior joints without seismically designed details. The experimental results indicate that the stirrup placed in the beam-column joint cores can effectively improve the shear strength of the joint and enhance the seismic performance, and the shear strength of the joints decreases when the beam-column depth ratio increases. The experimental results are also compared with the results predicted by two non-seismic design codes (Eurocode 2 and HK code 2013) and three codes for seismic design (Eurocode 8, ACI 318-14 and NZS 3101). In general, the current non-seismic design codes and seismic design codes of practice cannot accurately predict the shear strength of the exterior joints with non-seismically designed details. It is shown that neglecting the seismic design of beam-column joints may lead to potential damage of reinforced concrete framed buildings in unexpected moderate or low seismic areas