Experimental Research and Numerical Simulation on the Hysteresis Performance of Strengthened Beam–Column Joints

Beam–column joints in reinforced concrete frames are subjected to complex forces and are prone to damage under seismic actions. This paper proposes a method to strengthen beam–column joints using angle steel and split bolts. The hysteretic performance of the strengthened components is investigated through test and finite element numerical simulation. The influencing parameters, including concrete strength grade, axial compression ratio, stirrup characteristic value, angle steel leg length, and angle steel leg thickness, are analyzed. The results show that angle steel can simultaneously enhance the strength and stiffness of the strengthened joints. With an increase in concrete strength grade, the load-carrying capacity of the strengthened components continuously increases. However, when the axial compression ratio exceeds 0.6, the load-carrying capacity of the strengthened components significantly decreases. The size of the stirrup characteristic value has little influence on the shear resistance of the strengthened joints. The leg length and leg thickness of the angle steel have certain effects on the strengthening effectiveness. The method of outward movement of plastic hinges can effectively improve the seismic performance of bi-directionally loaded spatial joints.