Description
The highlights of many research projects are presented discussing the evolution of studies on Nickel-Titanium (NiTi) superelastic shape memory alloy bars that eventually led to their deployment in an actual bridge in Seattle, Washington, USA. The paper also briefly describes a new generation of SMA (shape memory alloy) bars that incorporate Cobalt (NiTiCo) and the related ongoing research to tap into its relatively high strength. The key questions that were answered through research on NiTi were if the superelasticity of NiTi is passed on to NiTi-reinforced beams. This followed by the recentering capability that these bars could provide to concrete members subjected to cyclic loads. Other important issues discussed in the paper are the connections of the bars to mild steel reinforcement, measures to avoid material waste by using the full bar diameter rather than machining the diameter to dog bone shape, and development of large diameter bars that are appropriate for use in actual bridge columns.
