Shape Memory Alloys (SMAs)

SMA is a type of high-performance metallic material, which is able to recover itself after undergoing large strain through unloading or heating. The charming feature of the SMA-based SC structural systems is the flag-shaped hysteresis behavior induced by SMAs under the loading and unloading process. This behavior is achieved from phase transformation between Austenite and Martensite. Residual deformation can be minimized by applying such innovative materials. In the meantime, in comparison with the PT tendons (which were also used in self-centering structural systems), SMAs can be fabricated into different shapes, which can cater to various structural systems. Moreover, SMAs show excellent corrosion resistance and good fatigue property. Typical applications of SMA-based SC structural systems include beam-column connections equipped with SMA bolts, SMA reinforcement in RC structures, SMA braces, and SMA SC dampers.

Superelastic SMA behavior

SMA U-shaped damper

(Wang and Zhu, 2018)

SMA bolts (with strain gauges mounted)

Some abbreviations:

SMA = Shape memory alloy

PT = post-tensioned

SC = self-centering