Abordagem multiescala do comportamento mecânico da microestrutura do concreto utilizando o método dos elementos de contorno

Abstract

This paper deals with the study of the mechanical behavior of concrete using a two- dimensional numerical modeling proposal on a microscopic scale. The material is considered to be composed of three phases being matrix, inclusions and interface zone, where each constituent is modeled appropriately. A Boundary Element Method (BEM) formulation for the multi-scale analysis of sheets is also presented, where Representative Volume Elements (RVEs) represent the structure of the material, modeled as a plate with sub-regions. The approach models the interfacial transition zone by means of cohesive contact finite elements, where a fracture and contact model is incorporated into the element, the inclusion is modeled as being a linear elastic material, while the matrix is considered as an elastoplastic material obeying the Mohr-Coulomb model. The main objective of the work is to show how a formulation based on computational homogenization is an advantageous alternative when compared to complex macroscopic constitutive models for the mechanical behavior of brittle materials. A series of examples involving the parameterization of concrete properties, the analysis of the influence of the size and amount of aggregates, the analysis of the influence of the amount of fracture and contact elements, and the analysis of the insertion of voids to represent concrete porosity, are presented in order to illustrate the performance of the proposed modeling. The results found show that the proposed modeling presents promising results for employment in a multiscale modeling. It also shows the importance of using fracture as well as pores to more faithfully represent heterogeneous materials.