Análise experimental da influência da adição de fibras e da variação da armadura de costura em consolos curtos de concreto armado

Abstract

Reinforced concrete corbels are usually characterized by being support elements whose design can be made from the Strut-and-Tie Method (STM) which is based on fundamental assumptions that consider that the tensile stresses are absorbed by the rods (structural steel) and the compressive forces are absorbed by the struts that are formed inside the concrete section, as it is understood that these elements have regions of discontinuity (D) or disturbances in the stress distribution. This method can be applied in the case of short corbels as they also present regions (D), given that their stress flow occurs in a non-linear manner. In this way, this experimental study analyzed the influence of the addition of synthetic fibers (polyethylene and polypropylene) and steel in the composition of the concrete, as well as, to verify the influence of the variation of the seam reinforcement rate in order to validate the MTB as a solution safe and efficient for the design of elements that present discontinuities (D) or disturbances. In the tests, the breaking load, the opening of cracks and the deformations in the tie rods, seam reinforcement and in the concrete, internally and externally, were observed. The results showed that the specimens containing synthetic fibers showed the highest strengths compared to the steel fiber specimen, being on average 10.82% more resistant than the reference specimens, despite not containing the highest fiber contents. In general, the elements showed similar ductile behavior and failure mode, so the cracks occurred in a controlled manner and there was no sudden rupture. As for the deformations in steel and concrete, the results showed a similar behavior among the specimens.