Numerical investigation on cyclic behaviour of superelastic shape memory alloy (SMA) dampers

In recent decades, researchers have developed many technologies like energy dissipating dampers to improve the response of structures in seismic events but still limitations persist in earthquake-resistant design. Residual drift is still a significant problem encountered while using dampers which results in a reduction in their performance. Many types of dampers have been introduced to localize the damages in a defined section of a structure to prevent structural failure and decrease the repairing cost. However, in general, rehabilitation of a structure using a damper is not an economical option because residual deformation occurs due to limitations of constituent materials of the damper. Therefore, in this paper, a shape memory alloys (SMAs) damper is proposed to mitigate the performance degradation problem caused by residual deformation of a structure and to reduce maintenance and repairing costs. The shape memory alloys can reduce residual deformation at room temperature due to the superelastic effect. In addition, a pretension force was applied to prevent damage by reducing the fastening force of the shape memory alloy bar and to improve the load performance. Finite element analysis was performed to verify the performance of the damper to which the pretension was applied. Furthermore, recentering performance and energy dissipation capacity of the damper were analyzed. The analysis results show that the proposed damper can reduce the residual strain by recentering, as well as improve energy dissipation and ultimate capacity.