Debonding mechanism of FRP strengthened flat surfaces: Analytical approach and closed form solution

Fiber Reinforced Polymer (FRP) composites represent an effective retrofitting strategy for the rehabilitation of masonry and concrete structures. The importance of adhesion between support and strengthening material is crucial and great research effort has been aimed at understanding this phenomenon from an analytical perspective. According to interfacial stress analysis, the debonding mechanism may be idealized and studied as an FRP–interface-support system with elastic FRP bonded to a brittle inelastic interface. In the present work, a fully analytical approach is developed to analyse the debonding mechanism of FRP strips applied to flat masonries providing a closed form solution characterized by few parameters governing the mathematical problem. Compared with other analytical methods, the present approach is advantageous in its closed form formulation, which allows the problem to be solved with a limited computational effort in a standard Matlab environment. The approach is benchmarked with two different sets of experimental results taken from the technical literature and from an ongoing investigation carried out by the authors. The results demonstrate the reliability of the method in analysing the debonding of FRP applied on flat masonry prisms.