Smart prestressing with thermo-induced Shape-memory alloy

Thermo-induced Shape-memory alloy (for short as SMA) is a composite functional material with shape-memory effect (for short as SME) and super-elasticity (for short as SE) in large deformation situation. Applying this property, SMA wires were elongated beyond their plastic limit under room temperature and subsequently were embedded in concrete beams under low temperature, thus a smart prestressing is obtained. In this. paper, basic principles and mechanical properties of smart prestressing are discussed, based on the relevant research and tests,the feasibility of inducing additional prestressing stress by SMA wires is also analyzed,and use this additional prestressing stress can control,adjust and make up the losses made by time history or other reasons. In another words, we can heat the SMA wires so as to induce phase changes,and great stress is got when the SMA wires is not free to deform,when we adjust the current or voltage the stress is changing accordingly on an as-needed basis,in this way can we get a smart prestressing.