Flexural performance of reinforced self-consolidating concrete beams containing hybrid fibers

Flexural performances of twelve reinforced self-consolidating concrete (SCC) beams containing steel fiber, macro polypropylene fiber, micro polypropylene fiber, and their combinations were studied at room temperature. The major test variables were fiber types, fiber contents and longitudinal reinforcement ratios. Cracking load, yielding load, ultimate load, mid-span deflection, longitudinal reinforcement strain and crack pattern of the reinforced SCC beams were investigated. It was found that the addition of mono steel fiber and hybrid fibers enhanced the ultimate bearing capacity but reduced the mid-span deflection of reinforced SCC beams. With the increase in fiber content, the longitudinal reinforcement strain, crack width and crack spacing decreased significantly. The hybrid use of steel fiber and micro polypropylene fiber did not have a further beneficial effect on the flexural performance of SCC beams at room temperature. Compared to micro polypropylene fiber, the macro polypropylene fiber displayed a more significant effect on the structural behavior of SCC beams. A calculation method for ultimate bearing capacity of flexural SCC beams at room temperature was proposed, which takes into consideration the effects of hybrid fibers. Comparisons were drawn between the predicted results of this proposed model and other previous models with experimental data in this study and previous literature. The results indicate that the proposed model can reasonably estimate the ultimate bearing capacity of SCC beams containing hybrid fibers subjected to flexural loading at room temperature.