AbstractThis work presents a numerical model to simulate the failure behavior of slender reinforced concrete columns subjected to eccentric compression loads. Due to the significant influence of the lateral displacements on the loading state provided by an eccentric load, geometric nonlinearity is considered. The responses of the concrete in tension and compression are described by two scalar damage variables that reduce, respectively, the positive and negative effective stress tensors, which lead to two different damage surfaces that control the dimension of the elastic domain. To describe the behavior of the reinforcements, truss finite elements with elastoplastic material model are employed. Interaction between the steel bars and concrete is modeled through the use of interface finite elements with high aspect ratio and a damage model designed to describe the bond-slip behavior. The results showed that the numerical model is able to represent the nonlinear behavior of slender concrete columns with good accuracy, taking into account: formation of cracks steel yielding crushing of the concrete in the compressive region and interaction between rebars and concrete.

O objetivo principal do trabalho é apresentar uma comparação entre distintas estratégias de simulação computacional de estruturas de concreto armado utilizando modelos de fissuração distribuída. Em uma primeira abordagem, foi adotado o modelo multidirecional de fissuração distribuída do programa DIANA empregando-se diferentes regras de amolecimento para o material fissurado (frágil, linear e não-lineares de Moelands-Reinhardt e de Hordijk). Posteriormente, foi utilizada a formulação DSFM - Disturbed Stress Field Model, modelando o concreto fissurado como um material ortotrópico com fissuras distribuídas do tipo rotacionais. Os programas DIANA e VecTor2 foram utilizados como ferramentas para avaliar a eficácia dos diferentes modelos no estudo de vigas de concreto armado submetidas a esforços de flexão.

The main goal of the present work is to present a comparison between two different strategies for the computational simulation of reinforced concrete structures, both using smeared crack models to represent the behavior of the materials. As a first approach, a multidirectional smeared crack model available in DIANA has been adopted along with different softening rules for the cracked materials (brittle, linear, nonlinear of Moelands-Reinhardt and Hordijk). Additionally, the Disturbed Stress Field Model - DSFM has also been adopted to model cracked concrete as an orthotropic material with smeared rotating cracks. The finite element codes DIANA and VecTor2 have been used to evaluate the performance of the different smeared crack models to predict the behavior of reinforced concrete beams subjected primarily to flexure.