Seismic displacement response of SDOF systems with SMA slip friction dampers

Owing to superelastic behavior, shape memory alloy (SMA) has been widely utilized to develop self-centering damping devices. Recently, the authors developed a novel SMA damper, i.e. the SMA slip friction (SMASF) damper. The cyclic behavior of the SMASF damper not only depends on the hysteresis shape factors of SMA bars, but also on the coefficient of kinetic friction and the slope of the friction plates. Hence, the basic working mechanism of the SMASF damper is different from that of conventional SMA dampers. In the early work, the features of the SMASF damper have been revealed by static cyclic loading tests. However, the seismic displacement responses of this novel damper remain unknown. To this end, this paper initiates with a brief introduction of the damper, including the configuration, working mechanism, and testing results. And then, extensive seismic analyses based on single-degree-of-freedom systems were conducted. Based on the constant-strength ductility demand spectra, the displacement responses of the SMASF damper were understood through the comparisons with conventional SMA damper and friction damper. A wide range of fundamental periods, strength capacities and seismic intensity levels were considered. Further, parametric analysis was conducted to assess the effect of the hysteresis shape factors of SMA bars and the coefficient of kinetic friction and the slope of the friction plates. This study also sheds light on the force-based seismic design method for this damper.