CHEMO-THERMO-MECHANICAL MODEL FOR MASSIVE CONCRETE AT EARLY-AGE BASED ON CREEP DAMAGE THEORY

Influenced by hydration of concrete, the early-age behavior of a massive concrete structure is a multi-physical field coupling process and it is prone to damage, to crack and to cause other harmful behaviors, which imposes a detrimental impact on the structural durability and safety in a long-term service period. To solve this problem, within the framework of classical damage mechanics, this paper develops a multi-field coupling model which comprehensively reflects the early-age behaviors of massive concrete, including cracking, creep, thermal deformation, autogenous shrinkage deformation and aging effect. A chemo-thermal model is established by combining the equation of hydration reaction and the heat transfer equation. The stress-strain relationship is based on the framework of elastoplastic damage theory. The damage-dependent microprestress-solidification theory is introduced to account for both linear creep and nonlinear creep. The thermal deformation and autogenous shrinkage deformation are described by the change of the temperature and the degree of hydration, respectively. The aging effects of concrete mechanical properties are also considered. Through the proposed model and the corresponding explicit numerical algorithm, the numerical simulation of the Maridal culvert is carried out, where the influence of concrete creep is investigated. Numerical results suggest that the model can predict the early-age cracking behavior of massive concrete structures and provides a meaningful reference for the analysis of mechanical behaviors of early-age concrete.