On the use of Shape Memory Alloys dampers to reduce the vibration amplitudes of civil engineering cables

Abstract

Cables used in civil engineering bridge has very low intrinsic damping rate which makes them particularly susceptible to vibration related to weather (wind, rain) and traffic. The associated displacement amplitudes are relatively small near the anchor (about 5 mm), as well as vibration frequencies (1-10 Hz). This may cause damage and affect the sustainability of structures and the safety of people. To avoid these phenomena, several stay cable bridges are equipped with dampers to reduce the amplitude of displacement. Deep studies on SMA for damping applications (i.e., fatigue / fracture analysis, SMA creep effects, aging actions) was the basis for the SMA application to morphing. In fact, from damping to morphing the requirements for SMA are more demanding and particular studies are necessary. This paper focuses on the assessment of the effectiveness of the use of shape memory alloys (SMA) dampers to reduce the vibration amplitudes of civil engineering cables. Mechanical behavior under cyclic loading of SMA wires is studied and super-elastic polycrystalline SMA model parameters are identified. Experimental tests were performed in a LCPC laboratory on a 50 meters long cable equipped or not with a two NiTi wires dampers (diameter: 2.46 mm). The experimental results shown, evidence of a dramatic decrease in the amplitude of displacement which reached about four times the experimental value determined for cable without SMA dampers.