NUMERICAL SIMULATION ON SELF-CENTERING BEAM-COLUMN JOINTS REINFORCED WITH SUPERELASTIC SMA BARS

In order to improve the energy dissipation capacity and self-centering capacity of the frame structure, an earthquake resilient beam-column joint based on super-elastic SMA bar was proposed. The numerical model of self-centering SMA reinforced concrete beam-column joints was established based on OpenSees finite element software platform, by using SMA material self-centering double-flag constitutive model, and nonlinear simulation under low-cycle reciprocating load was carried out to obtain the hysteretic curves and skeleton curves of the joints. The validity of the numerical model was verified by comparing the analysis data with the experimental results. The parameter analysis was carried out, considering the amount, length and yielding strength of SMA material, while the influences of SMA material parameters on the hysteretic performance and self-centering ability of the joints were analyzed. The results show that the concrete beam-column joints reinforced with super-elastic SMA bars have high energy dissipation and self-centering capacity. The numerical analysis model can well simulate the hysteretic behavior of self-centering SMA joints under low cyclic reciprocating loads. The mechanical parameters of SMA bars have a great influence on the seismic performance of joints. Under the condition of proper reinforcement, a larger SMA bars area leads to smaller residual displacement and stronger the self-centering capacity. Under the same condition, when the SMA bar exceeds the plastic hinge length, the length has little influence on the joint performance. Under the condition of proper reinforcement, increasing the yield strength of SMA can improve the bearing and self-centering capacity of the joint.