Crack velocity-dependent dynamic tensile behavior of concrete

Experiments have consistently shown that the tensile strength of concrete increases with increasing strain rate. The reasons for this phenomenon are not yet well understood and several hypotheses have been proposed in the past to explain it. This study offers additional insight through the application of dynamic fracture mechanics. The relationship between crack velocity and strain rate of concrete is first investigated using a cohesive zone model and fitted to available experimental data. The obtained relationship is then implemented into two different versions of crack-speed dependent dynamic fracture models. Both models show that computed strength versus strain rate responses compare favorably to well-established test data, suggesting that strain rate sensitivity is strongly associated with the characteristics of dynamic crack growth and inertial effects at the boundaries of the crack. A constitutive modeling scheme that incorporates the obtained dynamic fracture models into a meso-mechanical model is also proposed to predict stress–strain behavior of concrete under dynamic tensile loading. Comparisons between model predictions and published experimental data are provided to show the accuracy of the proposed framework.