Resistência ao cisalhamento de vigas de concreto autoadensável com adição de fibras de aço

Abstract

The use of self-compacting concrete has increased in recent decades due to several reasons, the main ones being its high fluidity, which dispenses with the use of concrete vibrators, ease of concreting and higher quality of the concrete due to better compacting, allowing the making of slender pieces and with higher reinforcement ratio. However, even self-compacting concrete exhibits brittle failure behavior and low tensile and shear strength, issues that can be mitigated with the use of steel fibers. Aiming to investigate the shear strength in self-compacting concrete beams with steel fibers, this study presents a database composed of 113 experimental tests reported in the literature. The data collected were analyzed to determine trends in the shear strength's behavior due to the addition of steel fibers in the SCC beams. Also, using the Root Mean Square Error (RMSE) and the Demerit Points Classification (DPC), empirical equations and code provisions for the prediction of the shear capacity of SFRC beams were evaluated. The results show that, unlike the concrete without the addition of fibers, the increase in the aggregate diameter decreases the shear strength with the use of steel fibers in SCC beams. Additionally, the increase in fiber volume corresponds to an increase in shear strength in concrete with a maximum compressive strength of 50 MPa. The results also demonstrated that the Root Mean Square Error (RMSE) is better for evaluating the precision but not the safety of the shear strength prediction equations, which is the best assessed by Demerit Points Classification (DPC). As for the shear strength prediction equations, the code predictions showed more safe and less conservative results than the empirical equations, being more suitable for design.