Coupled thermo-hydro-mechanical-phase field modeling for fire-induced spalling in concrete

This paper aims at developing an efficient numerical model to numerically reproduce the fire-induced spalling process taking place in concrete and to investigate the underlying mechanism of thermal spalling. To deal with complex crack patterns and with ease of extending to multi-physics problem, phase field method is employed for crack modeling. The primary objective of this manuscript is to develop a coupled thermo-hydro-mechanical-phase field model and the numerical solution framework. The effects of length scale parameter, staggered solution methods, and related factors on mechanical fields, as well as the impact of fracture on mass transfer and heat conduction are investigated. It is concluded that spalling is a result of combined thermal expansion and vapor pressure, among which thermal effect plays a major role and vapor pressure accelerates the occurrence of spalling.