Design and behaviour of steel braced frame reinforced with NiTi SMA wires

Shape memory alloys offer unique characteristics that can be utilized in enhancing the seismic performance of various types of structures. An innovative steel frame braced with tension-only pseudoelastic nickel-titanium (NiTi) shape memory alloy (SMA) wires was developed in this research for seismic retrofit applications. The structural performance of the developed system was experimentally compared with standard steel frame braced with tension-only plates. Three main parameters were investigated, namely, the ability of the system to achieve a self-centering response, the amount of energy dissipated and the ability to reach a target drift of 4%. Test results showed that the SMA braced frame had significant re-centering capabilities (i.e. recovered large portions of the post-elastic drifts), and a potential for moderate energy dissipation. Failure involved SMA wires slipping out of their anchorage which did not allow for their full utilization. This paper focuses on the design and experimental test of a control braced frame and an SMA braced frame.