An enhanced-deformability SMA damper: Experimental tests and seismic control analysis

Shape memory alloy (SMA) dampers are known for their efficacy in eliminating post-earthquake residual deformations for the protected structures. However, an excessive elongation demand would deteriorate the self-centering capability and may even lead to the rupture of SMA components. This means that severe earthquakes may cause SMA dampers to malfunction. However, the efforts paid on addressing this concern are relatively limited. As such, this paper proposes an enhanced-deformability SMA damper, which is a parallel combination of SMA bars and friction plates through geared transmissions. Firstly, the configuration, working mechanism and restoring force model of the damper are presented. And then, one reduced-scale specimen was fabricated for proof-of-concept tests. The testing results confirmed that the proposed damper had an enhanced elongation capacity, i.e., the damper could sustain a larger displacement than the SMA bars could. After that, one benchmark frame building was selected for discussing the effects of enhancing elongation on seismic responses of the protected structures. Nonlinear time history analysis was conducted to assess seismic responses . In addition, incremental dynamic analysis and fragility analysis were conducted to quantify the probability of damage. The results indicated that the enhanced-elongation mechanism reduced the failure risk of SMA dampers and increased the collapse prevention capacity of the structures. ● An Enhanced-Deformability SMA Damper (EDSD) is proposed, and proof-of-concept tests are carried out. ● The SMA bar and friction mechanism can effectively work in collaboration through the gear set. ● The EDSD is able to sustain a larger displacement compared to the SMA bars. ● The EDSD can reduce the failure risk of SMA dampers and increase the collapse prevention capacity of the structures. ● The protective effect becomes more pronounced as the deformability-amplification factor increases.