Long term exposure to high temperature strongly affects the durability and safety of con- crete structures due to the severe degradation process that takes place in this composite material. In effect, most of the relevant macroscopic mechanical features of porous…
Long term exposure to high temperature strongly affects the durability and safety of con- crete structures due to the severe degradation process that takes place in this composite material. In effect, most of the relevant macroscopic mechanical features of porous materials like concrete such as cohesion, friction, strength, stiffness and ductility, strongly depend on the temperature, temperature gradient and humidity, as well as on the governing stress state. At the macroscopic level of observa- tion, high temperature exposures cause significant modifications in the chemical features of cement paste. From the predictive analysis stand point, robust and reliable constitutive theories are required to accurately simulate the complex failure processes of concrete material subjected to high tempera- ture exposure. In this work, a thermodynamically consistent gradient poroplastic theory for concrete under high temperature is proposed. Herein concrete is considered as a closed porous medium while the relevant thermo-chemo-mechanical couplings that take place in the material subjected to temper- ature effects are taken into account. Thereby, the dehydration of cement paste when is subjected to high temperature exposure is the main responsible for the degradation processes of fundamental me- chanical properties. Regarding the gradient formulation a restricted form is considered whereby the state variables are the only ones of non-local character. A Temperature-Dependent Leon-Drucker- Prager (TD-LDP) strength criterion is proposed for porous material under high temperature fields and a numerical analysis by means of finite element simulations is presented to show the predictive capabilities of the proposed approach.