Comparison of Continuum Models in the Numerical Simulation of the Nonlinear Behavior of Concrete

Resumo

Concrete is a widely used material in civil engineering, characterized by its high heterogeneity, as it is composed of a cement paste and aggregates of varying shapes, sizes, and properties. This complex composition makes it difficult to accurately represent its behavior using classical solid mechanics models. Traditionally, structural analysis considers behavior based on the classical continuum model, also known as the Cauchy continuum, which simplifies the material as being composed of infinitesimal points. However, this approach may not be sufficient to faithfully represent materials with complex microstructures, such as concrete. In this context, generalized continuum models have emerged, such as the micropolar continuum, also known as Cosserat, and the micromorphic continuum. These models take into account the existence of microstructures with non-negligible dimensions, allowing each point in the material to have additional degrees of freedom, such as independent rotations and internal deformations. This formulation enables a more accurate representation of scale effects and local discontinuities. The present work aims to numerically simulate the nonlinear behavior of the same structure using the formulations of the three aforementioned continuum types, in order to compare the analysis efficiency, computational cost involved, and the accuracy of the results obtained. It is expected that the micropolar and micromorphic models will require greater computational effort but will provide results that are more consistent with reality, especially when considering the heterogeneity of concrete, which is not adequately represented by the simplifications of the classical continuum.