Failure Behavior of Precracked Concrete Beams Retrofitted with FRP

Abstract

The addition of fiber-reinforced plastic (FRP) laminates bonded to the tension face of concrete girders is becoming an attractive solution to the rehabilitation and retrofit of damaged structural systems. Flexural strength is enhanced with this method but the failure behavior of the system can become more brittle, often involving delamination of the composite and shear failure of the girder. This study first reviews failure modes including delamination with the use of FRP to rehabilitate various concrete structures and discusses methodologies used to characterize the failure processes of the system. Then, failure modes observed in an experimental program involving FRP-laminated laboratory models are reported. Physical models of reinforced concrete beams with variations in shear strengths, bonded laminate lengths, and epoxy types are precracked, then retrofitted with glass and carbon fiber-reinforced plastics and tested in an experimental program. Strengths are shown to increase with the addition of FRPs, but the specimens are observed to fail through a variety of mechanisms. Parameters affecting these failure modes are discussed, and techniques used in the analysis of these modes are reviewed. Results of this review are used to make recommendations for future work in the understanding of FRP retrofitted concrete behavior.