Bond Behavior of Steel Plates Externally Bonded on Concrete Elements

The traditional use of steel plates externally glued to Reinforced Concrete (RC) elements represents still a good solution for strengthening existing structures in comparison with the use of Fiber Reinforced Plastic (FRP) sheets and laminates due to relatively low prices, ductile stress-strain properties, possibility of increasing also the stiffness if serviceability performance needs to be improved, no limits for the strength increment percentage. However, few recent studies and guidelines are available for such a strengthening technique despite new and more efficient adhesive materials are currently available on the market aimed to make the bond behavior more and more efficient. Efficiency of strengthening technique is, indeed, mainly depending on bond behavior at the plate-concrete interface, which plays an important role in the possible debonding failure of externally strengthened elements and can be reliably investigated in detail by means of Finite Element (FE) models. In this paper, an in deep literature review of bond behavior of steel plates glued to concrete elements is reported by discussing the main parameters involved. Finally, an analytical mono-dimensional approach is developed and applied to simulate some experimental bond tests available in literature.