Effects of beam—column depth ratio on joint seismic behaviour

Abstract

Full-scale reinforced concrete (RC) exterior beam–column joints, which are fabricated to simulate those in as-built RC frame buildings designed to BS 8110, are tested under reversed cyclic loading. The seismic behaviour of these non-seismically designed joints is investigated. Particular emphasis is given to the effects of the beam–column depth ratio, column longitudinal reinforcement and stirrups in joints on the seismic performance and shear strength of the joints. It is shown that beam–column depth ratio has a significant effect on the shear strength and ductility of beam–column joints, while intermediate longitudinal reinforcement may be used to enhance the shear capacity and improve the hysteretic behaviour of beam–column joints, and links placed in beam–column joint cores can effectively improve the seismic behaviour and enhance the joint shear strength. Test results are compared with those predicted by three seismic design codes (ACI-318, NZS 3101 and Eurocode 8) and two non-seismic design codes (BS 8110 and Eurocode 2). It has been shown that member sizing and reinforcement detailing have significant effects on the shear capacity and seismic behaviour of exterior beam–column joints. In general, present seismic and non-seismic design codes do not accurately predict the shear strength of the non-seismically detailed joints, while BS 8110 may provide relatively better predictions than others in these particular cases.