Shear strengthening of reinforced concrete beams using epoxy-bonded FRP composites

The paper deals with the application of fiber reinforced polymer (FRP) laminates or fabrics as shear strengthening materials for reinforced concrete beams. The study aims at increasing the experimental database on shear strengthening of concrete using composites and, most importantly, developing an analytical model for the design of such members within the framework of modern code formats, based on ultimate limit states. The experimental part of the study involved testing of eleven concrete beams strengthened in shear with carbon FRP (CFRP) at various area fractions and fiber configurations, while the analytical part resulted in a model for the contribution of FRP to shear capacity in analogy with steel stirrups, with an effective FRP strain that decreases with increasing FRP axial rigidity. It is shown that the effectiveness of the technique increases almost linearly with the FRP axial rigidity and reaches a maximum, beyond which it varies very little.