Analysis of coupled transport phenomena in concrete at elevated temperatures

TL;DR

This paper develops and analyzes a numerical scheme for modeling hygro-thermal behavior of concrete at high temperatures, capturing pore pressure increases relevant to structural safety.

Contribution

It introduces a non-linear implicit scheme for the Bažant-Thonguthai model, proving existence and uniqueness, and demonstrates its effectiveness through numerical simulations.

Findings

Numerical scheme accurately reproduces pore pressure rise in heated concrete.

Model provides insights into thermally-induced spalling risk.

Finite element discretization ensures reliable simulation results.

Abstract

In this paper, we study a non-linear numerical scheme arising from the implicit time discretization of the Ba\v{z}ant-Thonguthai model for hygro-thermal behavior of concrete at high temperatures. Existence and uniqueness of the time-discrete solution in two dimensions is established using the theory of pseudomonotone operators in Banach spaces. Next, the spatial discretization is accomplished by the conforming finite element method. An illustrative numerical example shows that the numerical model reproduces well the rapid increase of pore pressure in wet concrete due to extreme heating. Such phenomenon is of particular interest for the safety assessment of concrete structures prone to thermally-induced spalling.