Meso-scale approach to modeling concrete subjected to thermo-mechanical loading

Concrete subjected to combined compressive stresses and temperature loading exhibits compressive strains, which are considerably greater than for concrete subjected to compressive stresses alone. This phenomenon is called transient thermal creep or load induced thermal strain and is usually modeled by macroscopic phenomenological constitutive laws which have only limited predictive capabilities. In the present study a meso-scale modeling approach is proposed in which the macroscopically observed transient thermal creep results from the mismatch of thermal expansions of the meso-scale constituents. The meso-structure of concrete is idealized as a two-dimensional three phase material consisting of aggregates, matrix and interfacial transition zones (ITZ). The nonlinear material response of the phases are described by a damage-plasticity interface model. The meso-scale approach was applied to analyze compressed concrete specimens subjected to uniform temperature histories and the analysis results were compared to experimental results reported in the literature.