AbstractThe constitutive compressive stress–strain response of hybrid high-performance, fiber-reinforced concrete (HyHP-FRC) containing steel and polyvinyl alcohol (PVA) fibers is scarcely reported. In this study, the compressive stress–strain behavior of plain high-performance concrete and 18 HyHP-FRC mixtures containing steel-PVA fiber systems were experimentally measured and analyzed. The incorporation of steel-PVA fibers significantly enhanced the postcracking stress–strain response of HyHP-FRC, including its compressive strength. Additionally, physical measurements revealed that the dosage and geometry of the steel fibers significantly affected the postcracking toughness of the concrete. Using the least-squares fitting approach and additional independent data, the volumetric reinforcing index of the fibers (RIv) and the predictive equations for the properties of the HyHP-FRC under uniaxial compression were established in terms of RIv. These equations indicated that the compressive strength of HyHP-FRC was linearly proportional to RIv; however, nonlinear correlations were observed for the elastic modulus and strain at the peak stress of HyHP-FRC. Finally, straightforward and more refined models for the full-scale constitutive compressive stress–strain curve of HyHP-FRC were developed and validated against the test and other data. The proposed models can be used to accurately predict the entire stress–strain response of cement-based composites containing hybrid combinations of metallic and synthetic fibers.