Seismic performance of full-scale self-centering reinforced concrete beam-column joints: Experimental, numerical and theoretical analysis

A reinforced concrete (RC) frame system with a self-centering joint connected with post-tensioned (PT) tendons and bolted angles was developed to overcome the limitations of precast system without reliable connection. The self-centering beam-column joints with a gap at the beam column interface are capable to resist severe earthquake with negligible residual deformation and minimal mechanical damage. However, a comprehensive understanding on effect of joint connectors including bolted angles and PT tendons on the seismic performance of self-centering joint (SCJ) is lacking. Three full-scale SCJ specimens were thus designed and tested under cyclic loading to determine the mechanical performance of SCJ and its influencing factors. The effects of bolted angles as energy dissipater and PT tendons as displacement controller were separately explored. The structural performance of SCJ was analyzed by finite element model, showing good agreement with the experimental results. A parametric study was conducted to further analyze the contribution of PT force and bolted angle to hysteretic response. Finally, the lateral load model of SCJ was established and the contribution of bolted angle and PT tendon was theoretical studied. The results indicate that the component elements (beam and column) remained undamaged after cyclic test, while the bolted angles experienced large deformation, dissipating substantial seismic energy. The gap at the beam-column interface of joint equipped with PT tendons was closed and the joint was perfectly self-centered by PT force exhibiting minor residual displacement after unloading. The PT tendons and bolted angles cooperated well, which enable the SCJ to be used as a connection in RC frame at high seismic region. Furthermore, the validated numerical model can be further used to predict the seismic performance of similar types of beam column joints. The simplified analysis model can provide a potential design reference in the application of RC self-centering systems.