A system of coupled transient differential equations governing heat, mass transfer, and pore pressure built up in porous media ( concrete) , subjected to intensive heating, is derived. Water vapor and liquid water are considered separately in the mass transfer formulation. The primary unknowns are temperature, water vapor content, and pore pressure of the gaseous mixture. A nite element formulation and corresponding owchart of computat ions of all required data are presented. The numerical example solved represent s a cross section of a concrete column exposed to re. The domain and time distributions of temperature, pore pressure, water vapor, and liquid water content are presented. Computed pore pressure is higher than those usually reported by ot her analytical studies. The in uence of some initial parameters ( permeability, initial water content, and porosity) on maximum pore pressure is investigated.
This paper presents a comprehensive model for simulating coupled heat and mass transfer in concrete when it is subjected to a fire. The model considers not only the transport of dry air, water vapour and liquid water but also the evaporation of liquid water and the dehydration of bound water. It can be applied to multidimensional problems. The governing equations describing this coupled heat and mass transfer phenomenon are solved using finite element methods with a standard Galerkin approximation. Results related to temperature, pore pressure, moisture content, the level of evaporation and dehydration of water within concrete for a standard fire curve are given. The influence of the liquid water transport on the spatial distributions of temperature and pore pressure is investigated through the use of parametric studies. The present results can be used to predict the potential of concrete spalling.
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