Research developments of a novel self-prestressing system for flexural strengthening reinforced concrete structures

The state of infrastructure in Canada is concerning, with many structures requiring rehabilitation or replacement in the near future. Researchers are investigating Fe-SMAs as a novel prestress strengthening system to address this need. The novel system provides a faster and more adaptable alternative to traditional methods. The straightforward and quicker installation system makes Fe-SMA feasible at any point in a structure's lifespan. The key to this system is its ability to self-prestress through the shape memory effect, developing recovery stress when restrained. This paper systematically reviews studies on the flexural strengthening of reinforced concrete (RC) beams using Fe-SMA, discussing the system’s performance, installation techniques (EB/EUB, NSM, CR), and long-term durability. It compares conventional prestress strengthening techniques and outlines key challenges and research directions. Findings suggest that Fe-SMA can effectively extend the service life of infrastructure by delaying deterioration while addressing the limitations of current methods. Fe-SMA offers advantages over traditional materials, such as steel and CFRP, including improved ductility, enhanced corrosion resistance, and cost-effectiveness. Its effectiveness has been demonstrated in real-life applications, such as the strengthening of a 113-year-old bridge, which showcases its potential for large-scale rehabilitation. Additionally, Fe-SMA offers environmental benefits, including ease of reintegration and the ability to be processed into new materials. The paper identifies challenges such as stress relaxation, non-uniform stress distribution during sequential activation, and the need for advanced anchorage systems. A notable feature is Fe-SMA's ability to recover stress losses through multiple activations, which requires standardized reactivation protocols. Future research should focus on quantitative cost and life-cycle analyses, as well as environmental impact assessments, to further validate the advantages of Fe-SMA.