Mechanics of debonding in FRP-plated RC beams

Both the flexural and shear strengths of reinforced concrete (RC) beams can be substantially increased using externally bonded fibre-reinforced polymer (FRP) reinforcement in the forms of sheets/strips/plates (all referred to as plates for brevity). Failures of such FRP-plated RC beams often occur by debonding of the FRP plate from the RC beam in a number of distinct modes. This paper provides a summary of the current understanding of the mechanics of debonding failures in FRP-plated RC beams largely based on the research of the authors and their co-workers. A systematic classification of possible debonding failure modes is presented following a brief outline of the common strengthening methods. The interfacial stresses and bond behaviour between FRP and concrete are then discussed before the mechanisms and processes of debonding failures are examined. Furthermore, advanced strength models for the key debonding failure modes are presented. The paper concludes with a brief discussion of future research needs.