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