Performance of self-centering devices containing superelastic SMA bars and their application via finite element analysis

This paper aimed to use finite-element analysis to evaluate the seismic performance of self-centering devices, containing superelastic shape memory alloy (SMA) bars and their application. It should be noted that the devices could perform bending behaviors combining with tensions or compression. Cyclic performance of the devices under pulling and pushing actions have been modelled and verified by previous experimental results. Then, parametric studies were conducted to investigate the effect of design parameters on the stiffness of the selfcentering devices containing SMA bars. An application of the device to a steel frame was proposed and modelled. Results shown that the increasement of diameters and number of SMA bars have positive effects while the increase of bars length and moment arms have negative effects on the effective stiffness of the devices. Besides, with the same area, the use of SMA bars in the rectangular shape gives higher effective stiffness than the use of those in the circular shape. However, with the same moment of inertia, the former gives lower effective stiffness than the latter. The hysteretic responses of a steel frame equipped with SMA devices showed perfect selfcentering capacity with symmetric behavior. The devices are effective to enhance the seismic performance of steel frames.