Analytical Model for Flexural Response of Reinforced Concrete Corbels Externally Strengthened with Fiber-Reinforced Polymer

In this paper, an analytical model to determine the bearing capacity and the load-deflection response of reinforced concrete (RC) corbels with main and secondary steel bars and externally strengthened with fiber-reinforced polymer (FRP) wraps or strips is proposed. The model considers a strut-and-tie mechanism in which the ultimate load was determined using multiple trusses constituted by main and secondary steel reinforcements, external FRP reinforcement, and compressed struts affected by a softening effect. A value of the maximum percentages of steel bars and FRP reinforcements was indicated to allow yielding of steel bars before premature debonding of FRP, FRP failure due to stress concentration, and crushing of the concrete strut. The expressions derived for prediction of the load-carrying capacity were compared with the ACI Code and with the most recently proposed formulas and computing procedures and proved to fit best the shear strengths measured in tests available in the literature. Compared with the other ones existing in the literature, the model presented is the only one that considers the simultaneous presence of secondary steel bars and FRP reinforcement.