Poromechanical approach for prediction of fire-induced fracture and moisture transport of structural concrete

This study introduces a novel poromechanical approach to analyse fire-induced fractures and transport phenomena, such as spalling, crack propagation, and vapour pressure, by accounting for gaseous kinetics.A key feature of this framework is that, across all temperature ranges, vapour diffusion and the bulk movement of vapour and liquid water maintain thermodynamic equilibrium, while being coupled with the structural response of concrete.The increase in vapour pressure with rising temperatures, the non-orthogonal fractures of concrete (cracks and spalling) caused by vapour pressure and thermal stress, and the subsequent reduction in vapour pressure were confirmed.Notably, the proper release of vapour pressure after concrete cracking helped to prevent excessive damage.Focusing on the safety assessment of concrete structures, the study also investigated the post-fire performance of a reinforced concrete (RC) shear wall in a nuclear power plant.The proposed model effectively evaluated crack occurrence due to temperature increases, accelerated liquid water and vapour transport, the decrease in vapour pressure from crack propagation, and rapid liquid water penetration during post-fire-curing.The remaining capacity of the shear wall after 400C heating was 95%, closely matching experimental results.