Heterogeneity Modelling of Concrete Structures by Nonlocal Damage Models

Resumo

The behavior of structural concrete is usually represented by considering the homogeneous material media and its macroscopic properties. The problem can be represented in more realistic models considering the material as a heterogeneous multiphase media. In representing heterogeneity, either a direct or indirect description of the phases can be considered. The direct approach considers the phases to be geometrically described in the discrete model. In the indirect approach, phases are represented by homogenizing their physical properties or by the random distribution of points in the domain with material parameters corresponding to each phase. In the physically nonlinear analysis using the Finite Element Method, a constitutive model capable of differentiating the response to tension and compression and computing the gradual cracking process of the concrete is necessary. Furthermore, these models must be coupled with regularization mechanisms to deal with numerically induced localization problems, such as the nonlocal approach. Given the above, this work proposes a model for representing the heterogeneity of concrete aiming at the physically nonlinear analysis of structures. Two phases will be considered to describe the heterogeneity: the cement matrix and the coarse aggregates, which will be incorporated into the discrete model using a hybrid method, which combines characteristics of direct and indirect methods. For material media degradation, a non-local damage model will be adopted with appropriate constitutive laws for each constituent material. Finally, numerical simulations will be presented to evaluate the model's characteristics.