Shear and bonding performances between Fe-SMA and steel for strengthening of steel structures

Abstract

Iron-based shape memory alloy (Fe-SMA) has been employed in China and the Czech Republic to reinforce steel bridges due to its outstanding self-prestressing characteristics. Nevertheless, the lack of theoretical guidelines necessitates this study to align with the practical Fe-SMA-reinforced applications in civil engineering. This study experimentally investigates the shear performance and load-transfer mechanism of 45 Fe-SMA/steel adhesive joints. Specifically, the shear characteristics of the adhesive joints affected by the various parameters of bonding layer thickness, steel plate thickness, bonding length and adhesive type are explored, the failure mode and load-displacement relationship are assessed, and some suggestions for optimization design are proposed. The experimental results demonstrate that the Fe-SMA/steel adhesive joints experiencing interface failure exhibit a linear load-displacement relationship. Contrarily, the load-displacement relationship of the adhesive joints under cohesive failure modes contains a yield segment. Longer bonding length results in more considerable failure evolution distances for Sika S02 and LPdur 03 specimens with cohesive failure, indicating better ductility of these specimens. Additionally, the epoxy adhesives of Sika S02 and LPdur 03 are preferred while employing Fe-SMA plates for bonding reinforcement of steel structures, which can maximize the characteristics of Fe-SMA to obtain stable and superior reinforcement performance. The experimental achievements have remarkable potentials for improving the in-service performance of old and damaged steel structures and other infrastructures.