Comparative Analysis of Coupled Thermo-Hydro-Mechanical Models for Concrete Exposed to Moderate Temperatures

This article compares and analyzes the performance of two thermo-hydro-mechanical (THM) models addressing the behavior of concrete structures subjected to thermomechanical loadings inducing moisture transfers. These models mainly differ by the fact that one relies on a unique mass conservation equation involving both water and vapor phases, while the other takes explicitly into account dry air and vapor in the gaseous phase. The comparison of the models is based on their ability to reproduce experimental observations performed on a concrete cylinder submitted to heating up to 200 C. Globally, both models provide a relatively good description of the specimen behavior. Whereas some differences may be noticed between the two models in particular regarding the gas pressure evolutions, the numerical results appear unexpectedly quite close. Finally, a numerical analysis on the respective importance of the fluxes due to Darcean and Fickean processes in both liquid and gaseous phase is performed. (authors)