Estudo experimental e numérico de vigas curtas reforçadas com PRFC à força cortante

Abstract

Reinforcement systems with carbon fiber composites may be employed for restoring the strength of a structural member, or to strengthen a structure to resist increased loading due to changes in structure utilization. In Brazil, there are still no technical standards that directly address the procedures for implementing reinforcements with carbon fibers, opening a wide field of study. The main models employed in the design of shear reinforcements with carbon fiber reinforced polymers are to use the analogy with steel reinforcement, considering that the reinforcement adds a portion to the resistive force to this effort. However, when deep beams are analyzed, they belong to regions of discontinuity, where the hypothesis of flat sections is no longer valid and other factors intervene in the behavior of the structure, being able to use the method of strut-and-tie to analyze structural elements. The main objective of this work is to study the mechanical behavior of reinforced concrete deep beams with carbon fiber composite subjected to concentrated loads, aiming to collaborate with the consolidation of theoretical models for the dimensioning of these structures. The methodology includes an initial stage to carry out a bibliographic review, followed by an experimental phase with the test of 36 beams and, following the accomplishment of numerical analyzes using the Finite Element Method. The experimental study was composed of three series of beams, varying the a / d ratio with values of 0.92, 1.7 and 2.4. Each series was composed of four different configurations of three identical specimens: beam without stirrups, beam with steel stirrups, beam with shear reinforcement in reinforced composite with carbon fibers and beam with steel stirrups and reinforcement to the shear force in reinforced composite with carbon fibers. The results showed the importance in considering the a / d ratio in the verification of the shear strength and confirmed the reinforcement efficiency. In addition, the confinement action of the reinforcement involving the whole beam contributed to the resistance of both the concrete and the complementary mechanisms to the trellis, being quantified as a function of the plot Vc and the ratio a / d. Finally, it is proposed to apply the strut-in-tie method using standard parameters, highlighting the need to consider the contribution of concrete tensile strength, interlocking of aggregates and the pin effect in the shear force resistant.