Debonding in FRP strengthened beams: Stress assessment versus fracture mechanics approach

In the present paper we analyze the debonding failure of abeam strengthened by a fiber reinforced polymer. We propose an analytical approach, whose basic assumptions are that (i) sections inside the beam remain plane and (ii) the adhesive layer acts as a shear lag. A stress concentration is found at the edge of the reinforcement length. Two failure criteria are proposed to study the debonding process. The former is a stress assessment criterion, i.e. failure takes place whenever the maximum tangential stress reaches a limit value (the interfacial bond strength). The latter is an energy, fracture mechanics criterion, i.e. failure takes place as long as the strain energy release rate due to debonding reaches a…