A re-centering deformation-amplified shape memory alloy damper for mitigating seismic response of building structures

This paper presents an innovative re-centering deformation-amplified shape memory alloy damper (RDASD) to reduce the responses of civil structures under earthquake motions. The damper can amplify the displacement deformation according to actual needs and fully exploit the energy dissipation capacity of superelastic shape memory alloy materials. Cyclic tensile-compressive tests of the fabricated RDASD are conducted to study the influence of the displacement amplitude and loading rate on the damper's mechanical properties. Additionally, a theoretical model of the RDASD that can precisely simulate the hysteretic characteristics of the damper is proposed. Finally, a nonlinear time history analysis is performed on a six-story steel frame for three cases: no dampers, dampers without deformation amplification, and dampers with deformation amplified by a factor of 2.5. The results show that the proposed RDASD can not only effectively mitigate the displacement, acceleration, and interstory drift responses due to its efficient energy dissipation capacity but also provide superior re-centering by amplifying the relative deflection for building structures. In practical applications, the recommended range for the deformation amplification coefficient of the damper is 2.0-3.0.