Shear strength of steel fiber self-compacting concrete beams

Abstract

The use of self-compacting concrete has increased for several reasons over recent decades but, mainly due to its high fluidity, which dispenses of the need for concrete vibrators, ease of casting, higher quality and better compacting, allowing the production of slender pieces, with a 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 collected from 113 experimental tests in the literature. Using the Root Mean Square Error (RMSE) and the Collins’ Demerit Points Classification (DPC), five code-based equations and ten experimental based equations for the prediction of the shear capacity of SFRC beams were evaluated. The results show that, unlike concrete without the addition of fibers, increase in aggregate dimensions decreases the shear strength with the use of steel fibers in SCC beams. Additionally, the increase in fiber volume corresponds to an increase in concrete shear strength with a maximum compressive strength of 50 MPa. The results also demonstrate that the Root Mean Square Error (RMSE) is better for evaluating the precision but not the safety of the shear strength prediction equations, which are better determined by Collins’ Demerit Points Classification (DPC). Code-based equations for ultimate shear strength prediction of fiber reinforced concrete beams presented results with satisfactory safety and economy.