Seismic performance of SMA-prestressed self-centering beam-column joints: Experimental and numerical study

This paper introduces a novel self-centering beam-column joint with dual restoring elements, utilizing shape memory alloy (SMA) and steel strands as the joint's restoring components. The primary advantage of this joint lies in the initial stiffness provided by the steel strands, which allows the performance of the SMA bars to be more fully realized. The SMA bars provide a more reliable load transfer path under large deformations, enhancing the joint's energy dissipation capacity, while their superelasticity prevents residual deformation. Through an analysis of the force mechanism, the key parameters influencing the joint's mechanical performance were identified. Two full-scale joints were subjected to low-cycle reversed loading tests to validate the rationality of the design approach. The results indicate that the joints exhibited minimal residual deformation, demonstrating excellent self-centering capability. The force-displacement hysteresis curves presented a dual-flag shape, emphasizing the structure's unique self-centering characteristics. The displacement ductility coefficients and equivalent viscous damping coefficients confirmed that the joints possess favorable deformation and energy dissipation capabilities. A refined ABAQUS finite element model was developed and validated against the experimental results, providing further analysis of key parameters related to the seismic performance of the structure.