Strain Rate Effect in the Mesoscopic Modeling of High-Strength Steel Fiber-Reinforced Concrete

The research presented in this paper aims to investigate the behavior of a high-strength steel fiber-reinforced concrete (HSSFRC) mesoscopic finite element model, at compressive high strain rates. In order to produce a three-dimensional meso-scale finite element model, a computer code is developed to randomly produce mesoscopic models of SFRC specimen. The specimen is assumed to be reinforced by 0.6 percent volume fraction of hooked steel fibers (Dramix RC-65/35-BN) with random positions and orientations. Aggregates of the compound are assumed to have spherical shape and are produced according to Fuller grading curve. Based on the initial mesoscopic model, a finite element model is produced and used in the explicit dynamic simulation. The contribution of inertial confinement in the dynamic strength enhancement of concrete at high strain rates was investigated and its effective role was observed. Accordingly defining a Dynamic Increase Factor (DIF) for mortar matrix led to overestimation; nevertheless, the inertial confinement by itself could not justify the increment of specimen strength under the dynamic loading. Obtained results also show that steel fibers have a negligible influence on the strength, strength enhancement ratio (DIF) and post peak behavior of the model at high strain rates.