Stress-strain relationship of airfoiled-shaped milled-cut steel fiber-reinforced concrete under uniaxial compression: Experiments and analytical model

The long-term service of concrete structures to severe environments has driven up performance requirements in terms of durability, crack resistance and toughness. Milled-cut steel fiber (MSF) holds great potential for corrosion resistance and reinforcement of concrete, benefiting from its optimized geometric and surface properties. The stress-strain relationship and damage characteristics of milled-cut steel fiber-reinforced concrete (MSFRC) under compression can serve as experimental and theoretical foundations for structural design. Thus, this study conducted compression tests on MSFRC at three different contents ( V f =0.6 %, 1 %, 1.4 %) and investigated the experimental analysis results of the full-range compressive response. Crimped steel fiber (CSF) and hooked-end steel fiber (HSF) were selected as comparison groups to confirm the effect of fiber geometry. Failure mode, toughness, and parameters characterizing the uniaxial compressive behavior of various steel fiber-reinforced concrete were experimentally assessed. The results indicate that the addition of MSF fibers increases the toughness of concrete by over 25 % compared to other types of fibers. MSF prevents the propagation of axial primary cracks and controls the maximum crack width to less than 1 mm. The negative effect of high fiber dosage on compressive strength is mitigated in MSFRC, and the optimal strength and toughness can be achieved when containing 1 % volume fraction fibers. Empirical formulas are developed to accurately predict the compressive strength and elastic modulus of MSFRC by incorporating a fiber reinforcing index (RI), with R 2 value of 0.93. Furthermore, a constitutive model describing the complete stress-strain behavior under uniaxial compression has been developed for MSFRC.