Cyclic nonlocal anisotropic damage modelling of concrete mesostructures with real-shaped aggregates

Abstract

Modelling and computing concrete mesostructures subjected to loads alternating between tension and compression are challenging. This paper presents a full computational model, from the random packing of real-shaped aggregates at the meso-scale to the FE computations with nonlocal anisotropic damage for alternate (cyclic) loading. Concrete is represented as a two-phase random heterogeneous material consisting of mortar and aggregates. Aggregates diversity and realism are reproduced by importing shapes from a laser-scanning database. Each elastic aggregate is described by several hundreds of facet vertices, packed using Oriented Bounding Boxes. The anisotropic nature of damage induced by loading in concrete is reproduced by assigning a nonlocal integral damage model to the mortar. A new cyclic dissymmetry (material) parameter enables the reduction in compressive strength after tensile loading to be modelled with modularity. Three-dimensional computations of the concrete mesostructures can then be performed for real-shaped aggregates without compromise, i.e., accounting for anisotropic damage of the mortar phase and key feature of the present work, dealing with alternate (cyclic) loading. The damage constitutive equations and their numerical implementation offer robustness up to high levels of damage and induced anisotropy in three-dimensional specimens. Concrete heterogeneities enhance damage evolution and induced anisotropic behaviour within the mortar matrix.