Fiber Reinforced Plastic (FRP) sheets are being used for strengthening existing reinforced and prestressed concrete structures. The effectiveness of the strengthening relies on the load-transfer between the concrete and the FRP. It has been shown that strengthened beams often fail…
Fiber Reinforced Plastic (FRP) sheets are being used for strengthening existing reinforced and prestressed concrete structures. The effectiveness of the strengthening relies on the load-transfer between the concrete and the FRP. It has been shown that strengthened beams often fail due to shear debonding at the FRP-concrete interface, which results in the delamination of the FRP from the concrete substrate. The failure is caused by a crack, which forms and propagates in a thin layer of concrete beneath the FRP. Results from shear tests performed on concrete blocks strengthened with FRP sheets are presented in this paper. The strain distributions in concrete and FRP were determined using an optical technique known as digital image correlation. The results show that the debonding process can be described in terms of crack propagation through the interface between concrete and FRP. The data provides information to determine the stress versus relative displacement (cohesive fracture behavior) and the fracture parameter GF (fracture energy).