Numerical Analysis of Behavior of Corbels Strengthened with Carbon Fiber-Reinforced Polymer

Reinforced concrete corbels in precast structures are the most popular type of connection between beams and columns. Nonetheless, corbels collapse in most cases in a catastrophic and sudden way due to a variety of factors. Despite the fact that numerous studies have been conducted to strengthen the damaged concrete elements with external reinforcement techniques, there are only a few studies have been conducted specifically to investigate the effects of external reinforcement by fiber-reinforced polymer on the shear response. The present paper aims to simulate the nonlinear structural behavior of reinforced concrete corbels externally strengthened with carbon fiber-reinforced polymer strips. Therefore, a case study of corbel was chosen in order to elaborate a several three-dimensional finite element models by varying in amount, direction, and thickness of the carbon strips. The reliability of the numerical models was validated by comparing the numerical results to the data of experimental campaign of previous published studies. The validated model was then used in a parametric study to investigate the major parameters that significantly influence corbel behavior, such as the influence of the compressive strength of concrete and the effect of the secondary reinforcements. The results showed that the diagonal reinforcement limited shear crack propagation and widening, resulting in a gain in load capacity of up to 66%. In addition, the increase of the ratio of shear span-to-effective depth a/d from 0.5 to 1.0 decreased load capacity by up to 40%, which confirmed that the corbel strength is much affected by increasing span–depth ratio. Moreover, the thickness of the carbon strips has more effect on the ultimate load, ductility, and toughness of the corbels, especially in inclined configuration resulting in an increase in shear capacity up to 123%. The increase in the compressive strength of concrete leads to improve the shear capacity by up to 57%. Furthermore, the incorporation of horizontal secondary reinforcement contributed along the depth of the corbels to an additional strength gain of up to 16%. The numerical behavior results are rather well-matched to those found experimentally in the term of load–deflection curves.