ABSTRACT
This study presents a poromechanical approach for analysing fire-induced fractures and mass transport phenomena in reinforced concrete (RC) structures. The model integrates multiphase flow and gaseous kinetics within the multi-scale simulation platform, enabling coupled evaluation of vapour pressure, cracking, and moisture migration under extreme thermal conditions. Comparisons with the diffusion model demonstrate that the poromechanical model captures localized rapid transport along cracks and provides more realistic predictions of thermal damage. The poromechanical model is further applied to assess the post-fire performance of scaled cylindrical RC walls representing the reactor pressure vessel pedestal in a nuclear power plant. Simulation results show that rehydration during post-fire curing contributes significantly to strength recovery after 400 °C heating, while severe degradation occurs at 800 °C heating. The proposed poromechanical model offers a rational and safety-oriented tool for evaluating RC structures under high-temperature exposure.
