Shear post‐cracking behavior of high‐strength fiber‐reinforced concrete: Experimental and analytical investigation

Abstract The use of fiber‐reinforced concrete (FRC) has grown globally in recent decades in applications such as slab‐on‐grade foundations, tunnel linings, and architectural elements. In addition, FRC has been explored for replacing or supplementing transverse reinforcement in beams. This practice is governed by international standards that define limits on concrete compressive strength, fiber type and quantity, and minimum performance criteria for FRC. Various methodologies have been employed to assess the shear strength of FRC, but no standardized evaluation method exists. This study aims to evaluate the direct shear strength of high‐strength fiber‐reinforced concrete (HSFRC), considering fiber type, fiber content, and concrete compressive strength as key variables. The research investigated combinations of concrete strengths (C55, C70, and C90) and the use of steel and polymeric fibers at 0.5% and 1% volume fractions. Tests were performed to measure compressive strength, modulus of elasticity, residual tensile strength, and shear strength, using both the JSCE‐SF6 method and the push‐off test. The results reveal that fiber inclusion significantly enhances shear strength, with notable differences based on fiber type and content. Steel fibers outperformed polymeric fibers at equivalent volume fractions, and higher fiber content led to greater shear strength. Additionally, the study highlighted the variations in shear strength results depending on the testing methodology, emphasizing the need for standardization. Existing models for predicting FRC shear strength were found to require adaptation for both fiber type (steel vs. polymeric) and testing method (JSCE vs. push‐off). A new model for predicting shear strength was proposed, along with a correlation coefficient between the JSCE and push‐off tests.