Qian et al. 2008
The authors discuss the effectiveness of an innovative energy dissipation device: the HSMAFD. Shake table tests were conducted with and without this passive energy-dissipating device that also exhibits re-centering capabilities. SMAs dissipate energy through the martensitic phase transformation in the metal instead of yielding, sliding friction, or deformation of viscoelastic solids or fluids. Moreover, SMAs have unique properties such as the superelasticity effect, extraordinary fatigue resistance, corrosion resistance, high damping characteristics and a temperature dependent Young’s modulus. These properties make them particularly suited for seismic.
System Concept
HSMAFDs are composed of pre-tensioned superelastic SMA wires and friction devices. The superelastic wires mainly performed a function of re-centering due to the large restoring force that returns them to their original shape. They also dissipate energy through their hysteretic response. The friction devices serve as the main energy dissipaters of seismic energy by relative sliding between friction plates.
The hysteretic behavior of the HSMAFD includes re-centering and energy-dissipating features. With the increase of the displacement amplitude, the energy dissipation per cycle increases almost linearly, while the secant stiffness and the equivalent damping decrease.
Experimental Study, Results and Discussion
A scaled 3-story steel frame with HSMAFDs was subjected to cyclic loading. Three earthquake historical records were used. The results showed that HSMAFDs were effective in suppressing the dynamic response of building structures subjected to strong earthquakes by dissipating a large portion of energy through their hysteretic deformation response. From the test results, the fundamental frequency of the structure increased more than 50% after HSMAFD were installed. The energy-dissipating system thus provided supplemental stiffness to the original structure.
Reference
Qian, H., Li H. N., Song G. and Sun L. (2008). “Shaking Table Tests on Steel Frame Building with Innovative Hybrid SMA Friction Devices,” Proceedings of the 14th World Conference on Earthquake Engineering 2008, Beijing, China, October 12-17.