Effects of steel fiber and strain rate on the dynamic compressive stress-strain relationship in reactive powder concrete

Three types of steel fiber-reinforced reactive powder concrete (SFRPC) with steel fiber contents of 0%, 2%, and 5% by volume are tested under dynamic compression by using a 40-mm-diameter split Hopkinson pressure bar (SHPB) apparatus. Data from SHPB experiments are employed to analyze the influence of critical parameters on the dynamic compressive stress-strain relationship of SFRPC at high strain rates. Test results show that steel fiber has a significant effect on the stress-strain relationship and energy absorption of RPC. Peak strain and peak stress increase with the increasing steel fiber content at the identical strain rates. A dynamic compressive damage-softening model for SFRPC at high strain rates is put forward on the basis of the Weibull distribution of SFRPC strength. A theoretical formula for E_d was established in order to ascertain E_d for the proposed constitutive model. The ratio of E_d to static elastic modulus E_s increases with increasing strain rate and decreasing steel fiber content. The proposed constitutive model captures the dynamic compressive stress-strain relationship of SFRPC, and theoretical results are in agreement with measured data.