Seismic Performance of a New Assembled Bolt-Connected Concrete Beam-Column Joint: Experimental Test and Finite Element Modeling

A new assembled bolt-connected concrete beam-column joint is proposed, aimed at completing the repair of a post-earthquake node by replacing the bolts and precast beams. Low-cycle loading tests were performed on two new full-scale connections to investigate the effect of bolt strength on the seismic performance of the new connections. A finite element model was established based on the experimental node specimens and compared with the experimental results to verify the accuracy of the finite element simulation results. The seismic performance of the new joints under different axial ratios was studied using finite element software to determine the effect of the axial pressure ratio on the seismic performance of the new joints. Based on the research carried out, a new improved joint was designed, numerical models of the improved joint were established using finite element software, and the seismic performance of the improved joint was compared with the results of the experimental simulation to analyze the seismic performance of the improved joints. The results of the study showed that the bolts and precast concrete beams are the main load-bearing members in the period of service. The joint can be repaired by replacing the bolts and precast concrete beams under seismic action, which meets the new joint design concepts. The finite element simulation results are in good agreement with the experimental results. The larger the axial compression ratio, the earlier the failure stage of the concrete, and the faster the bearing capacity and ductility decrease. The larger the axial compression ratio, the higher the initial stiffness of the joints and the greater the rate of stiffness reduction. The bolt stress distribution of the modified and optimized joints is more satisfactory. This change in node form can improve the recovery efficiency of the joint to a certain extent.