Interfacial constitutive model of Fe-SMA-and-steel single-lap-shear bonded joints

Abstract

Strengthening in-service steel structures can improve operational performance and extend service life. Employing Fe-based shape memory alloys (Fe-SMA) for proactive reinforcement stands out as a highly satisfactory and safe repair solution. For Fe-SMA-and-steel bonded joints, the load-bearing capacity can reach twice the recovery stresses obtained from activating Fe-SMA. Grounded in the experimental results, the failure process, stress/strain evolution, and force transmission mechanism of bonded joints are analyzed. The loading process of bonded joints before thorough failure undergoes two stages: loading growth and debonding development. In the debonding failure process, the effective bonding length of Fe-SMA-and-steel bonded interfaces, that resists external loads, remains essentially unchanged. Based on 3 types of structural adhesives and 4 types of adhesive thicknesses, the bond-slip constitutive models of bonded interfaces are derived from the experimental bond-slip curves, and the bilinear bond-slip constitutive models, i.e., the triangular cohesive zone models, are established through simplification to facilitate engineering applications. Moreover, the theoretical calculation methods are proposed for the interfacial constitutive parameters. This research provides experimental and interfacial constitutive foundations for the numerical simulation and theoretical calculation of bonded joints, and furthermore offers guidance for practical applications of repairing steel structures by bonding Fe-SMA.