Role of hoops on shear strength of reinforced concrete beam-column joints

This study investigated the effect of joint hoops on the shear strength of exterior reinforced concrete beam-column joints subjected to earthquake-type loading. Nine exterior reinforced concrete beam-column subassemblages were tested under reverse cyclic loading. All test specimens were designed to have adequate shear strength of joints, determined by the softened strut-and-tie model. The parameters considered include the amount and detail of joint hoops. Test results indicated that the major function of the joint hoop is to carry shear as a tension tie and to constrain the width of crack. A lesser amount of hoop reinforcement with a wider spacing could be used without significantly affecting the performance of joints. Test data also demonstrated that a beam-column joint with-, out hoop bars can exhibit satisfactory seismic behavior, as long as the joint is provided with adequate shear strength.