Bond degradation at environmentally exposed FRP-strengthened steel elements: State of the art

Due to several advantages that Fiber Reinforced Polymer (FRP) composites offer in comparison with other strengthening techniques for steel structures, they have attracted considerable interest over the past three decades. However, the efficiency of FRP-strengthening for structures was found to be highly dependent on the quality and durability of the adhesive bonding between FRP and steel surface. This paper presents a state-of-the art review on the bond degradation in FRP-steel joints under different environmental conditions. Topics reviewed in this paper comprise the effect of different environmental conditions and their combination on bond durability, synergic effect of combining environmental condition with mechanical load, and the recent developments in the numerical simulation of aged bond. The paper concludes with the research gaps and uncertainties for further investigations.