Experimental Study for the Effect of Steel Fibers Types and Volume Fraction on the Flexural Performance of RC Beams

Abstract

This research explores the structural response of reinforced concrete beams (RCBs) enhanced with steel fibers (SFs), focusing on both mechanical strength and flexural behavior. The investigation examined how variations in fiber geometry and dosage affect performance under flexural loads. A series of seven beam specimens, each 20 cm wide, 25 cm deep, and 1.5 m long, were subjected to four-point bending tests. The fibers used included straight, hooked-end, and corrugated types, incorporated at different volumetric ratios. The study also assesses the adequacy of current code predictions in comparison with experimental results. Notably, beams containing hooked-end fibers at a 1% volume fraction demonstrated the greatest performance gains. Specifically, specimens with 3 cm and 5 cm hooked-end fibers exhibited increases in ultimate load capacity of 12.05% and 13.64%, respectively, while deflection capacity increased by 137.83% and 140.73%. The findings reveal that the addition of hooked-end fibers significantly improves flexural strength and ductility. However, existing design models were found to substantially underestimate the ultimate moment capacity. The ACI code predictions were approximately 45% lower, and those of EC2 were about 50% lower than the experimental results. These outcomes indicate the necessity for revision in current design practices to more accurately represent the behavior of steel fiberreinforced concrete.