Bond of fiber-reinforced polymer laminates to concrete

Fiber-reinforced polymer (FRP) laminates are being successfully used worldwide for strengthening existing reinforced concrete structures. The bond of FRP reinforcement to the concrete substrate is of critical importance for the effectiveness of the technique. In this project, flexural test specimens were prepared to address some of the factors expected to affect bond, namely, bonded length, concrete strength, number of plies (stiffness), ply width, and to a limited extent surface preparation. Experimental results are presented and discussed herein. A linear bond stress-slip relationship, along with a simple shear model for the evaluation of the slip modulus, is used to predict the strain distribution at moderate load levels. Finally, expressions of the peeling load and rite effective bond length are presented. A design equation is proposed for calculating she effective FRP ultimate strain to be used in design to account for bond-controlled failure.