Seismic performance of the SMA-disc spring damper and its application in shear walls

Based on the material properties of disc springs and superelastic shape memory alloy (SMA) bolts, this study proposes an SMA-disc spring damper (SMA-DSD). This design successfully overcomes two major limitations of conventional disc spring dampers: inadequate tensile resistance and insufficient energy dissipation capacity. This study presents the fundamental configuration and working mechanism of the SMA-DSD. Through finite element analysis, we theoretically investigate the seismic performance of the damper, establishing and validating a reliable restoring force model. The seismic performance of the damper is evaluated under different displacement amplitudes, followed by comprehensive parametric studies on key design parameters: SMA diameter, SMA bolt preloading force, and precompression of disc springs. Results demonstrate that the SMA-DSD exhibits full, distinctive “double-flag“ shaped hysteretic curves across all displacement levels, indicating superior energy dissipation and self-centering capabilities. Furthermore, the design effectively overcomes the tensile resistance limitation of conventional disc spring dampers. Parametric analysis reveals that increasing SMA diameter enhances both the energy dissipation capacity and secant stiffness, while higher preloading force improves initial stiffness, but excessive preloading should be avoided. Similarly, increasing the precompression of disc springs increases stiffness but reduces both energy dissipation capacity and maximum deformation capability. Implementation of SMA-DSDs in replaceable corner-shear walls creates a self-centering concrete shear wall with an SMA-disc spring damper (SCSW-SMA-DSD). Comparative simulations demonstrate that the SCSW-SMA-DSDs exhibit superior seismic performance, characterized by stable, full hysteretic loops, non-degrading bearing capacity, secondary stiffening behavior, and significantly reduced residual deformation. These findings fully confirm that the synergistic interaction between the superelasticity of SMA and the restoring capability of disc springs, in SMA-DSD effectively mitigates residual deformation and enhances the seismic performance of shear walls.