Numerical analysis of the thermal active restrained shrinkage ring test to study the early age behavior of massive concrete structures

Several tests, devoted to the study of cracking due to autogenous and drying shrinkage, exist in the literature. They are generally not relevant for the study of massive structures for which thermal strains plays a key role. Therefore, an active ring test has been developed to study cracking due to restrained thermal shrinkage. This test is an evolution of the restrained shrinkage ring test which allows us to take into account both autogenous and thermal shrinkage. With this test, the early age cracking due to thermal restrained shrinkage (effect of the temperature rate), the influence of reinforcement and construction joints have been studied (Briffaut et al. (2011) [1]). Nevertheless, in this test, several phenomena occur simultaneously (hydration, shrinkage, creep…) and their effect cannot be easily decoupled. So, complementary tests have been performed to study each phenomenon separately and the ring test has been numerically simulated in order to identify coupling between creep and damage and to quantify the strength decrease due to construction joints. A good agreement between experimental and numerical results has been obtained for ring with reinforcement and construction joints. With the proposed model and the identified materials parameters validated on the active restrained ring test, numerical simulations of the construction of a real massive structure have been performed, and a parametric study has been achieved to highlight the creep effect.