Evaluation of dynamic increase factor models for steel fibre reinforced concrete

The use of steel fibre reinforced concrete (SFRC) in protective structures against extreme loading conditions (e.g. high-velocity impact and blast) has gained worldwide interest in recent years, which is attributed to its advantages of higher tensile strength and better energy absorption capability compared to normal concrete. This paper presents a comprehensive review of the dynamic increase factors (DIF) for both compressive strength and tensile strength of SFRC reported in the literature. In particular, the influences of matrix strength, fibre shape and fibre volume fraction on the rate sensitivity of SFRC are investigated. A versatile DIF formula is then proposed based on the reported data for describing the dynamic material strength of SFRC, which considers the effects of various parameters in one unified formulation for the first time. To demonstrate the effectiveness and feasibility of the proposed DIF formula, a 3D finite element model is established, and the proposed DIF formula is employed to simulate the dynamic responses of SFRC plates under impact. The developed finite element model is validated by comparing the predicted results with experimental data.