A Multi-Mechanism Damage Model for Concrete Structures Based on Microstructural Stress Analysis
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A damage model is proposed to describe the progressive deterioration of concrete caused by multiple interacting phenomena. The model is built on a micromechanical framework that captures cracking within various regions of the concrete microstructure through a plastic strain described. In this approach, concrete is treated as a composite material consisting of mortar and aggregates, which may be affected by Alkali-Silica Reaction (ASR). A mean-field homogenization technique is used to estimate the stress distribution within the aggregates, the mortar, and at their interface. These stress concentrations are then linked to damage variables defined for each phase and along the principal directions of the macroscopic stress tensor. This enables the representation of anisotropic degradation mechanisms such as aggregate cracking, interface debonding, and mortar damage. The evolution of these damage variables is thus driven in a coupled manner by different deterioration processes, including differential thermal expansion between mortar and aggregates, swelling pathologies, and external mechanical loading. The model proposed here can easily account for anisotropic damage that can occur, for instance, in the case of ASR swelling under confined condition. Moreover, in addition to variables representing distributed damage, the model introduces additional variables to account for localized damage and scale effects. This ensures the applicability to the practical modeling of civil engineering structures using the finite element method.
