Numerical study of the FRP-concrete bond behavior under thermal variations

In a context where daily and seasonal temperature changes or potential fire exposure can affect the mechanical response of structures strengthened with fiber-reinforced polymer (FRP) composites during their life cycle, the present work studies the bond behavior of FRP laminates glued to concrete substrates under a thermal variation. The problem is tackled computationally by means of a contact algorithm capable of handling both the normal and tangential cohesive responses, accounting for the effect of thermal variations on the interfacial strength and softening parameters, which defines the failure surface and post cracking response of the selected specimen. A parametric investigation is performed systematically to check for the effect of thermo-mechanical adhesive and geometrical properties on the debonding load of the FRP-to-concrete structural system. The computational results are successfully validated against some theoretical predictions from literature, which could serve as potential benchmarks for developing further thermo-mechanical adhesive models, even in a coupled sense, for other reinforcement-to-substrate systems, useful for design purposes in many engineering applications.