Análise de modelos computacionais para avaliação do comportamento mecânico do concreto fissurado

Abstract

The use of numerical methods, such as the finite element method, allows the development of models capable of simulating the mechanical behavior of concrete taking into account its physically non-linear behavior, allowing for more realistic analyzes of the material. One of the main phenomena responsible for the physical nonlinearity of concrete is cracking, which occurs even at low loading levels, due to its low tensile strength when compared to the compressive one. In this context, the present work aims to to present and evaluate two computational models to simulate the static behavior of concrete structures during the cracking process and to make a comparison between them. The first model analyzed considers smeared cracking and it is based on monitoring the deterioration of the material’s physical properties. The cracking process is described by the decay of stresses with increased strains, through different stress-strain relationships extracted from the literature that represents the overall behavior of concrete in tension or compression. The model formulation is based on the inversion of flexibility with the use of a local secant constitutive matrix, which takes into account the damaged and the undamaged secant Young’s modulus of the material. The second model evaluated considers the crack described discretely and it is based on the use of interface elements inserted in the mesh when the stress level in the continuous elements reaches a pre-established limit. Both models analyzed were implemented using an isoparametric element for plane elasticity and an incremental-iterative subroutine with load and displacement control methods. The implemented cracking models were validated by comparing the calculated results with the ones obtained by other models from literature, showing good agreement.