Mixed DEM/FEM Modeling of Advanced Damage in Reinforced Concrete Structures

Abstract

This paper aims to present a mixed, or combined, numerical approach to modeling advanced degradation and predicting failure in reinforced concrete (RC) structures. The discrete-element method (DEM) is used to model the cohesive behavior and fracturing of concrete, whereas the standard finite-element method (FEM) is applied to represent steel reinforcement through an elastic-plastic beam model. Because of specificity in the geometric support, which does not allow for hierarchical mesh refinement, convergence of the spherical DEM has never been proved, making it difficult to master DE simulations. In this paper the authors present results of a computational study conducted by means of deforming a DEM sample and varying several parameters, which allowed determining the minimum discretization required for a DEM sample to correctly reproduce the macroscopic behavior of concrete, and thus evaluating consistency of the spherical DEM used herein. An original steel-concrete bond model, developed to simulate the interaction between the steel and concrete models, is also presented. This model was devised to decouple normal and tangential responses, which allows fitting them separately in accordance with experimental data. The numerical simulations of tests performed on unreinforced and reinforced concrete samples and the modeling of the hard-type impact on a RC beam indicate the relevance of the proposed approach for simulating advanced damage in civil engineering structures under both static and dynamic loads.