Simulation of spatially non-uniform frost damage in RC beams under various exposure and confining conditions

Abstract

This paper aims to investigate the spatially non-uniform frost damage process in RC beams during large numbers of freeze/thaw cycles (FTC). The material-based thermodynamic and poromechanical frost damage models have been up-scaled to the structural level considering the anisotropic stress-strain conditions and the condensed water movement in the crack system. The ice-induced pore pressures are also integrated in the smeared RC element in consideration of the path-dependent nonlinear constitutive laws. The frost damage accumulation processes (referred as the expansive strain) are simulated with different depths of heat and moisture exposure, as well as various arrangements of reinforcing bars. Based on the proposed empirical model which links the expansive strain with the reduction in ultrasonic velocity, the 3D frost damage profiles are compared with 2D ultrasonic velocity data, which show a satisfactory agreement. Finally, the effects of different steel and structural confinements on the frost damage profile are numerically investigated and discussed in detail.