Shear Capacity of Precast Prestressed Concrete Beam-Column Joint Assembled by Unbonded Tendon

Very recently in Japan, a new guideline for seismic performance evaluation in prestressed concrete buildings was established by the Architectural Institute of Japan (AIJ), and it proposes that the shear strength of precast prestressed concrete (PCaPC) beamcolumn joints assembled by post-tensioning unbonded tendons- called "unbonded PCaPC" frames-can be evaluated from the provision for reinforced concrete (RC) structures. However, due to the volume loss of core concrete in a beam-column joint and no bonding action resulting from no-grout injection into the sheaths, the joint panels of unbonded PCaPC frames are more vulnerable to shear input than those of RC structures. Therefore, reversed cyclic loading tests using subassemblage specimens for beam-column joints in unbonded PCaPC frames, where the joint shear failure preceded, were performed to evaluate their shear capacity. In this paper, the shear strength and behavior of beam-column joints in unbonded PCaPC frames were investigated based on the test results, and the joint shear input was compared with the nominal shear strength of RC joint panels, as proposed in the AIJ provision. Additionally, the nominal shear strength of RC beam-column joints from the American Concrete Institute, New Zealand Standards and Eurocode 8 was introduced, and their applicability to the joints of unbonded PCaPC frames was discussed.