Flexural Response of UHPFRC Beams Reinforced with Steel Rebars

This article compares the flexural responses of ultrahigh-performance fiber-reinforced concrete (UHPFRC) specimens and their normal-strength concrete (NSC) counterparts through an experimental study. Four UHPFRC specimens reinforced with 2 % steel fiber (by total volume of concrete) with a length of 13 mm and a diameter of 0.2 mm were used with longitudinal steel rebars at different reinforcement ratios to determine their flexural responses. For comparative purposes, three NSC beams were also tested. Results were compared with relevant equations in the literature. Moreover, the fracture energy of the specimens was compared to provide a better understanding of the ductility in the two types of beams. Results showed better performance of UHPFRCs in terms of peak load, fracture energy, and moment capacity as compared with their NSC counterparts. Failure in UHPFRC specimens with high reinforcement ratios was dominated by shear-flexure patterns, while flexure patterns were dominant in specimens with low reinforcement ratios. Failure of NSC specimens, on the other hand, was characterized by shear, regardless of reinforcement ratio. Additionally, available equations for moment capacity of ultrahigh-performance concretes (UHPCs) appear too conservative, especially for higher reinforcement ratios. Lastly, statistical models were proposed to predict the load-displacement curves of UHPFRC dogbone and beam specimens, which fitted well with experimental results with correlations over 0.90.