Interfacial stresses in plated beams

Fibre-reinforced plastic (FRP) or steel plates can be bonded to the soffit of a beam as a means of retrofitting the beam. In such plated beams, tensile forces develop in the bonded plate and these have to be transferred to the original beam via interfacial shear and normal stresses. Consequently, debonding failure may occur at the plate ends due to a combination of high shear and normal interfacial stresses. This paper starts with a review of approximate closed-form solutions for interfacial stresses, identifying their assumptions and limitations, thereby clarifying the differences between these solutions. This review also establishes the need for a similar but more accurate solution, and such a solution is presented next in the paper. This new solution is intended for application to beams made of all kinds of materials bonded with a thin plate, while all existing solutions have been developed focusing on the strengthening of reinforced concrete (RC) beams, which allowed the omission of certain terms. Finally, numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters.