Iron-based shape memory alloy strips for strengthening RC members: Material behavior and characterization. (10th June 2018)

• Record Type: Journal Article
• Authors: Shahverdi, Moslem; Michels, Julien; Czaderski, Christoph; Motavalli, Masoud
• Is Part Of: Construction & building materials. Volume 173(2018)
• Page Start: 586
• Page End: 599
• Publication Date: 2018-06-10
• Subjects: Shape memory alloy (SMA) -- Iron-based SMA (Fe-SMA) -- Recovery stress -- Shape memory effect (SME) -- Prestress -- Material characterization; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.04.057
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Production of iron-based shape memory alloy (Fe-SMA) strips at industrial level for civil engineering applications. Fe-SMA strips were characterized for application as externally fixed reinforcements for RC members. The relaxation behavior of Fe-SMA strips for durations of more than 1000 h was studied. The effects of different parameters on the recovery stress of Fe-SMA strips are investigated. Long Fe-SMA strips are activated in air by resistive heating. Abstract: Shape memory alloys (SMAs), in the form of bars and strips, can be used as prestressing elements in new reinforced concrete (RC) members or for strengthening existing RC structures, owing to their special characteristic known as the shape memory effect (SME). When the SME comes into play, the material returns to its initial shape upon heating after having been deformed at ambient temperatures. If a return to the initial shape is prevented by mechanical fixation, stress develops in the SMA. A cost-effective iron-based SMA (Fe-SMA) has been developed for application in civil engineering structures. The composition of the developed alloy is Fe–17Mn–5Si–10Cr–4Ni–1(V, C) (mass%). This Fe-SMA exhibits high tensile strength, excellent shape recovery stress (prestress force), and high elastic stiffness. Moreover, its material cost is low and it is easier to manufacture than nickel-titanium (NiTi) alloys. Recently, Fe-SMA strip production has been started at an industrial scale. In this study, the experimentally determined properties of such industrially produced Fe-SMA strips are presented, and their recovery stress and recovery strain have been measured. The effects of prestraining and maximum heating temperature on the obtained recovery stress have been studied. These Fe-SMA strips can be used as external end-fixed reinforcements to strengthen RC structures.