Cracking resistance of ultra-high performance fiber reinforced beams
Abstract
Cracking resistance of ultra-high performance fiber reinforced beams
Incoming article date: 03.07.2025The paper investigates the formation and propagation of flexural cracks in beams made of ultra-high performance steel fiber reinforced concrete (UHPFRC). A comprehensive series of laboratory tests was carried out on seventeen beams of rectangular and T-shaped cross-sections, varying in longitudinal reinforcement ratios, fiber volume contents, and fiber types (straight and wave-shaped). The results demonstrate that the inclusion of steel fibers significantly enhances the crack resistance of the beams, promotes a more uniform crack distribution, and improves their load-bearing capacity. In under-reinforced UHPFRC beams, failure typically occurs due to fiber pull-out localized within one or more dominant cracks. Prior to the onset of deformation localization in the tensile zone – which coincides with the yielding of the longitudinal reinforcement – the crack widths in fiber-reinforced specimens remain below 0.25 mm. This behavior ensures that even under service-level loads (65–70% of ultimate), the crack openings stay within the allowable design limits (0.3–0.4 mm). The experimental findings contribute to a better understanding of the cracking mechanisms in UHPFRC beams and provide a valuable foundation for refining numerical models and optimizing design approaches for flexural members made of advanced high-performance cementitious composites.
Keywords: ultra-high performance concrete, beams, bending moment, steel fibers, flexural cracks