Experimental and analytical investigations of shape memory alloy as passive energy dissipation device for seismic response reduction of building

An innovative shape memory alloy (SMA) -based damper, using the pseudoelasticity of SMA wires, has been developed in this study. The SMA wire in the damper is always elongated when it is installed between the stories of a structure and subjected to earthquake excitations, and thus the buckling of the SMA wire can then be avoided. The tests were conducted to investigate the pseudoelastic property of a NiTi wire with a diameter of 1.2mm. The test results indicated that the pseudoelastic hysteresis loop of the NiTi wire is dependent on the loading frequency (< 2Hz) and cyclic loading number (<15), however, independent of the loading frequency (<2Hz) and cyclic loading number(> 15). Shaking table tests of a scaled 5-story steel moment-resistant frame incorporated with the SMA dampers at the first story were carried out. The test results indicated that the SMA damper can suppress structural seismic response effectively. Finally, the ARX models are employed to model the frame-damper system and the model parameters are further identified using the Least Square and Kalman Filter algorithms respectively. Furthermore, the frequency and modal damping ratio are also obtained from the ARX models of the frame with and without dampers.