Material and Geometric Heterogeneity Consideration for Cracking Risk Prediction of Young Age Behavior of Experimental Massive Reinforced Concrete Structure

Abstract

This article presents the application of a thermo-hydro-chemo-mechanical (THCM) model to a real complex structure of reactor confinement (mock-up VERCORS from EDF) by taking into account the specificities of the construction (construction consequences), the distributed reinforcements and the material heterogeneity of massive structure. The experimental campaigns were conducted during and after the construction of VERCORS. The early-age behavior of concrete is first modelled based on a multiphasic hydration model to ensure the thermal evolution. Then a 3D mechanical model is used to predict the consequences of hydration, temperature and water variations on mechanical behavior. An alternative approach to consider the structural effect of distributed reinforcement without explicit meshing of reinforcements is implemented and is able to reproduce the influence of reinforcement on the crack patterns. Moreover, the “Weakest link localization” method is also adapted to deal with a probabilistic scale effect due to the material heterogeneity of massive structure. It permits to assess directly the most likely tensile strength which can treat the first crack in softening part of the loaded volume of structures.

Numerical prediction of cracking risk of reinforced concrete structures at early age

“…This technique has been applied to predict the early behaviour of the inner vessel of the Vercors model (a 1/3 scale model of a containment vessel), where it was applied within the framework of our participation in the international benchmark study organized by EDF on this subject [56]. More specifically, the aim was to assess the strains and cracking pattern of the lower part of the vessel (gusset + lower part of the wall) during the first few weeks after casting.…”

Uncertainty propagation through Thermo-Hydro-Mechanical modelling of concrete cracking and leakage – Application to containment buildings

“…So, the water loss by drying is decoupled from water consumption due to hydration. (2) where are the water and cement content in the design mix respectively (kg/m 3 ), fitting parameters and a thermo-activation function.…”

“…Given the large number of inputs and the computational time of each THM-L calculation, our interest is geared towards Local Sensitivity Analyses (LSA) which are less costly compared to the Global ones (GSA) 2 . Indeed, our goal is to define the most influential parameters even qualitatively; though the approximation of the statistical 2 The main drawback of local approaches is that their associated derivatives provide information only at the base point where they are computed; whereas the global ones take into account the rest of the variation range of the model's parameters. moments might be less precise.…”

“…In particular, the simulation of concrete cracking in large structures is still mainly performed in a deterministic way [1][2] though it strongly depends on the way concrete's mechanical properties are scattered (especially the tensile strength [3] and the Young's modulus [4]). On one hand, and to address such limitation, several authors have chosen to explicitly model concrete's spatial heterogeneities using discretized and FE-projected Random Fields [5][6].…”