Joint Contribution to the Deformation of RC Beam-Column Sub-Assemblies
In this paper, the contribution of joint shear deformation to the overall storey-drift of reinforced concrete (RC) beam-column sub-assemblies is investigated experimentally. Two lightly reinforced beamcolumn sub-assemblies, one without any hoops inside the joint core and the other with hoops significantly less than that required by the incumbent seismic design codes, were tested under a constant axial compression and gradually increasing reversed cyclic displacements. Both specimens experienced severe damage in the joint due to excessive shear deformation of the joint core. Unlike in seismically designed ductile frames, joint shear deformation accounted for more than 50% of the overall storey-drift in the tested specimens. Comparison of the two test results showed that a small amount of hoops in the joint core, though not enough to satisfy seismic requirements, helps to confine the joint core and to inhibit the joint shear deformation to some extent.