Experimental investigation of a novel SMA-friction self-centering brace with adjustable mechanical characteristics

To achieve an optimal balance between self-centering capability and energy dissipation performance, this study proposes and experimentally evaluates an adjustable SMA-Friction Self-Centering Brace (SFSCB), comprising NiTi shape memory alloy (SMA) cables arranged in parallel with frictional components. The working mechanism of the SFSCB is introduced, and its adjustable advantages over conventional SMA cable bracing are discussed. A series of cyclic loading tests were conducted under various conditions to investigate the effects of adjustable pre-pressure in frictional components, initial pre-tension in SMA cables, as well as loading frequency and loading displacement on the SFSCB behavior. The SFSCB exhibited flag-shaped hysteresis loops, excellent self-centering ability, stable energy dissipation, and minimal residual deformation. Increasing frictional force significantly enhanced the energy dissipation capacity with minimal impact on the self-centering behavior. The pre-tension in SMA cables contributed to reduced residual deformation and improved transition stiffness, while its influence on peak strength was limited. The SFSCB was found to be insensitive to frequency effects, achieving a maximum strain of 12.4% and a peak strength of 172.4 kN. Fatigue tests showed that, despite progressive SMA degradation, stable frictional dissipation enables the SFSCB to retain 67.5% of its energy dissipation capacity even after a 61.4% strength loss over 500 cycles. The findings highlight the SFSCB’s suitability for seismic-resilient structures by showing that its hybrid mechanism enables precisely controllable energy dissipation and a recentering capacity that can be tuned from partial to full self-centering.