Experimental investigation on seismic performance of two types of member-panel zone unified joints for precast concrete moment-resisting frame

Recently, precast concrete (PC) moment-resisting frame (MRF) is widely used for lateral load-resisting systems in buildings such as semiconductor factories requiring a short construction period and high quality of materials, but its application is limited to high-seismicity regions due to complex in-situ assembly between PC members and low seismic performance of joints. This paper presents the evaluation on cyclic behavior of two types of member-panel zone unified PC joints, in which the panel zone is unified with a PC beam or column, designed for use in high-seismicity regions. Two specimens of the member-panel zone unified joints and a benchmark specimen of cast-in-place joint (CIP) were tested under cyclic loading and were analyzed about crack patterns, failure mode, hysteretic behavior, shear distortion, and reaction moment of beams to compare the cyclic behaviors of PC joints with the CIP joint. The seismic performance of each specimen was evaluated in terms of allowable drift ratio, strength & stiffness degradation and energy dissipation capacity suggested in the current code. The maximum strength of the beam-panel zone unified PC joint was comparable to that of the CIP joint, and the crack pattern and failure mode were found to be similar to that of the CIP joint with shear failure of the panel zone. The seismic performance of the beam-panel zone unified PC joint satisfied the criteria applicable to special MRF. On the other hand, the column-panel zone unified PC joint exhibited the flexural failure of the PC beam due to a biased distribution with a high bending moment on either beam, which significantly contributed to a low maximum strength than that of the CIP joint. In spite of relatively low strength, the seismic performance of the column-panel zone unified PC joint satisfied the criteria except for the allowable drift ratio. It was shown that the member-panel zone unified PC joint can be applied as the special MRF by improving the workability and securing high seismic performance. •Cyclic tests on two types of member-panel zone unified PC joints were conducted to investigate seismic performance compared to cast-in-place joint.•Two distinct failure modes were observed depending on PC members unified with panel zone.•Gap-opening between PC beam and panel zone significantly reduced strength of joint contrary to gap-opening between PC column and panel zone.•Column-panel zone unified joint showed low strength due to biased bending moment to one side