Effect of elevated temperature on dynamic flexural-tensile failure of geometrical-similar concrete beam: A meso-scale study

Abstract

The investigations on the influence of geometric dimension on concrete failure at normal temperature have made a fruitful progress, while the investigations on the size effect of concrete at elevated temperature approach blank. For investigating the influence of elevated temperature and dimension on static and dynamic failures of concrete, a 3D thermo-mechanical coupling method considering the meso-structural characteristics of concrete and the strain rate effect of material was established. Flexural-tensile failure analyses of concrete beams with different geometric dimensions were conducted after heat conduction analysis. The results reveal that the speed of the heat transfer is relatively fast in small-sized concrete and the heat conduction behavior quickly approaches an equilibrium state. There is a significant degradation behavior on dynamic flexural-tensile strength for concrete exposed to fire. The elevated temperature can weaken the strain rate hardening-effect of concrete. At normal temperature, the influence of geometric dimension on dynamic flexural-tensile strength can be weakened at low strain rates while there is a reverse size effect at high strain rates. At elevated temperature, with the increasing geometric dimension, the flexural-tensile strength first decreases and then increases at low strain rates while the strength increases steadily as subjected to high strain rates.