EARTHQUAKE VIBRATION CONTROL DEVICES BASED ON SHAPE MEMORY ALLOYS: A REVIEW

Shape memory alloy (SMA) is a novel functional material in different shapes (wires and bars), physical characteristics (alloy composition, thermomechanical treatment and material phase) and stress modes (tension, torsion, bending and shear), which have the ability to return to former shape when subjected to an appropriate thermomechanical procedure. The shape memory effect (SME) and pseudoelasticity, two major properties of SMA associated with the thermal-induced or stressinduced reversible hysteretic phase transformation between austenite and martensite phase. Recently, research efforts have been extended to using SMA for control of civil structures. Some shape memory alloys like NiTi show noticeable high damping property in pseudoelastic range. Due to its unique characteristics, the NiTi alloy is commonly used for passive damping applications in which the energy may be dissipated by the conversion from mechanical to thermal energy. This paper presented a review of operation mechanism, design and experimental results of these SMAbased devices. The aim of the all reviewed experimental program was to examine the performances of the SMA elements under the working conditions they should be subjected to in a feasible seismic device, under repeated earthquake-like excitations. This paper also exhibited that SMA bars subjected to torsion, especially the martensitic ones, have great potential for their use in seismic devices due to their considerable energy dissipation capacity and outstanding fatigue resistance.

کلیدواژه ها:

shape memory alloys ، pseudoelasticity ، passive energy damper ، fatigue resistance ، seismic devices