Development of a novel deformation-amplified shape memory alloy-friction damper for mitigating seismic responses of RC frame buildings

Abstract

Super-elastic shape memory alloys (SMAs) are widely used to mitigate seismic responses of engineering structures because of their self-centring and energy dissipation characteristics. However, the energy dissipation capacity of SMAs is limited when compared to other displacement-dependent dampers. In this paper, a novel deformation-amplified SMA-friction damper (DASMAFD) is proposed to control the seismic responses of reinforced concrete (RC) frame buildings. In this damper, a lever system is employed to amplify the deformation that is transferred from the structure to the SMA wires, and a friction adjusting system is adopted to adjust the friction force in the damper. Hence, the proposed novel system is advantageous due to the excellent self-centring capacity of SMAs and the high damping capacity of the friction adjusting system. To demonstrate the effectiveness of the proposed system, the design and mechanism of the device are presented in detail, the self-centring and damping capacity of the damper are investigated through experimental studies, and the influences of deformation amplification ratio (DAR) and friction ratio (FR) on the self-centring and hysteresis characteristics of the damper are systematically examined. The damper is then applied to control the seismic responses of a 10-storey RC frame building, and numerical simulations are performed to examine the control effectiveness of the proposed system. The calculated responses of the building controlled by a conventional SMA damper are compared with those of a SMA-friction damper. Furthermore, parametric studies are performed to examine the effects of key parameters of the damper, namely DAR and FR, on the seismic responses of the building. Numerical results indicate that DASMAFD exhibits the most evident control effectiveness when compared to other dampers.