NUMERICAL MODELING OF COUPLED THERMO-HYGRO-MECHANICAL PROCESSES IN CONCRETE AT HIGH TEMPERATURE

A hierarchical mathematical model for analysis of coupled thermo-hygro-mechanical processes in concrete at high temperature is presented. The concrete is modeled as deforming porous media filled with two immiscible pore fluids: gas mixture and liquid mixture, at immiscible-miscible levels. The mathematical model consists of a set of coupled, partial differential equations governing the mass balance of the dry air, the mass balance of the water species, the mass balance of the matrix components dissolved in the liquid phases, the enthalpy(energy)balance and momentum balance of the whole medium mixture. The governing equations, the state equations for the model and the constitutive laws used in the model are given. The finite element procedures are developed for corresponding non-linear coupled problems to numerically simulate thermo-hygro-mechanical behavior causing material failures in concrete subjected to fire and thermal radiation. Numerical results demonstrate the performance and the effectiveress of the proposed model and its numerical procedures in reproducing coupled thermo-hygro-mechanical behavior in concrete.