Shape memory alloys for prestressed strengthening of steel structures: A review

Shape memory alloys (SMAs) have emerged as innovative materials for strengthening of steel structures. They possess the unique ability to generate prestress through the shape memory effect (SME), eliminating the need for supplementary tensioning equipment. This study presents a state-of-the-art review on SMAs for prestressed strengthening of steel structures. The material properties of SMAs are comprehensively summarized and analyzed. The connection methods of SMAs in strengthening strategies are systematically discussed. Subsequently, from the perspectives of strengthening effectiveness and material cost, the study conducts an in-depth comparative evaluation on various strengthening methods, including the use of iron-based SMAs (Fe-SMAs), nickel-titanium-based SMAs (NiTi-SMAs), and their composite patches that composed of SMAs and carbon fiber-reinforced polymer (CFRP) materials. Finally, based on a comprehensive review of existing studies, critical challenges and research gaps are identified, as well as recommendations for future investigations are proposed. This study extends the understanding of SMA materials for prestressed strengthening of steel structures and provides some useful suggestions for the repair scheme.