Effect of inertia and test approach on the high-strain-rate tensile behavior of steel fiber reinforced concrete

High strain rate loadings lead to fundamental modifications in the tensile stress-strain response of steel fiber-reinforced concrete (SFRC). These modifications include higher tensile strength and corresponding strain and fracture energy. This paper investigates the effect of strain rate on the tensile behavior of SFRC, covering ranges from quasi-static (10⁻⁶ to 10⁻¹ s⁻¹) to impact (10–50 s⁻¹). For this purpose, an instrumented drop-weight test setup was developed. The instrumentation includes a high-speed response data acquisition, a high-speed video camera, two fast response load cells, one clip gauge, and two strain gauges. Axial and transversal inertia effects were considered during the impact process to reach the real tensile behavior of SFRC. The effects of strain rate on the stress–strain and stress versus cracking opening displacement relations, tensile strength, and fracture energy of SFRC are obtained and discussed in both quasi-static and impact ranges. Novel models are proposed for predicting the strain rate effect on the tensile strength and fracture energy of SFRC, considering the type of tensile load applied. The models proposed in the current study are compared with the experimental results obtained within this research and those available in other studies. The findings demonstrate that incorporating the influence of inertia and employing the proposed models for the testing approach markedly enhances the accuracy in predicting the dynamic tensile behavior of SFRC.