Cracking localization and reduced ductility in fiber-reinforced concrete beams with low reinforcement ratios

• Effects of steel fibers on the flexural behavior of RC beams was studied.
• Cracking localization was observed in fibrous RC beams with low reinforcement ratios.
• Localization corresponded to measured curvature distributions along the beams.
• This cracking localization was accompanied with reduced structural ductility.
• Load capacities were higher with fibers only in beams with low reinforcement ratios.

The effect of adding steel fibers to concrete mixes on the flexural behavior of reinforced concrete (RC) beams was studied experimentally. Tests were conducted on conventionally reinforced beams with different reinforcement ratios, with and without fibers. Results show that the application of steel fibers leads to a pronounced reduction in flexural ductility of beams with low conventional reinforcement ratios (ρ < ∼0.5%). Ductility ratios of fibrous RC beam specimens were reduced by 50–80% compared with corresponding ratios measured on control specimens with the same reinforcement ratios but without fibers. The effects of added fibers on the flexural behavior of RC beams were examined and three aspects were reported: ductility ratio (based on deflection), distribution of curvature, and load-carrying capacity.