  A mathematical model allowing coupled hygro-thermo-mechanical analysis of
spalling in concrete walls at high temperatures by means of the moving boundary
problem is presented. A simplified mechanical approach to account for effects
of thermal stresses and pore pressure build-up on spalling is incorporated into
the model. The numerical algorithm based on finite element discretization in
space and the semi-implicit method for discretization in time is presented. The
validity of the developed model is carefully examined by a comparison between
experimental tests performed by Kalifa et al. (2000) and Mindeguia (2009) on
concrete prismatic specimens under unidirectional heating of temperature of 600
${\deg}$C and ISO 834 fire curve and the results obtained from the numerical
model.
