Estudo do comportamento mecânico de pavimentos de concreto com agregado reciclado reforçado com fibras de aço pelo Método dos Elementos Finitos
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Data
2023-04-19
Autores
Siqueira, Alana Helena Cara
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O ramo da construção civil está em constante evolução e por trás dos efeitos positivos que isso proporciona, se encontra uma consequência não muito agradável, representada pelo aumento da quantidade de resíduos de construção e demolição (RCD). Na maioria das vezes, a solução encontrada para o depósito destes resíduos consiste no seu despejo em aterros ou lixões e até mesmo em terrenos baldios e regiões próximas a rios e estradas. Este fato contribui com a geração de danos ambientais e por isso a utilização dos RCD como agregado reciclado tornase uma saída sustentável para o problema em questão. Neste contexto, esta pesquisa visa determinar se a técnica de modelagem numérica baseada no Método dos Elementos Finitos (MEF) consegue prever adequadamente o comportamento mecânico do concreto com agregado reciclado (CAR) reforçado com fibras de aço aplicado em lajes de pavimentos rígidos e lajes lisas armadas, contribuindo assim com o estudo da reutilização dos RCD. A modelagem tridimensional das lajes utiliza elementos finitos unidimensionais de barra para discretizar as barras e fibras de aço, que são acoplados por meio dos elementos finitos de acoplamento (EFAs) na malha de elementos tetraédricos da matriz de concreto, levando-se em consideração a perda de aderência existente entre o concreto e as fibras, assim como o modelo de dano à tração do concreto e os modelos constitutivos de seus reforços, ressaltando que o concreto é modelado como um material homogêneo (escala macroscópica). A metodologia aplicada se mostrou adequada, visto que os resultados numéricos foram semelhantes aos experimentais, apontando que o aumento da porcentagem de substituição dos agregados naturais por reciclados diminuiu a capacidade de resistência mecânica, ductilidade e dissipação de energia das lajes de concreto, sendo estes efeitos revertidos com a adição de fibras de aço na estrutura. Diferentes valores de resistência à compressão do concreto, cuja britagem origina os agregados reciclados, também influenciaram o comportamento mecânico das lajes de pavimentos rígidos.
The civil construction area is in constant evolution and even though it provides very positive effects, there is a not very pleasant consequence, represented by the increase in the amount of construction and demolition waste (CDW). Usually, the solution found for the disposal of these residues consists of dumping them in landfills or dumps and even in vacant lots and regions close to rivers and roads. This fact contributes to the generation of environmental damage, which is why the use of CDW as recycled aggregate becomes a sustainable solution to this problem. In this context, this research aims to determine if the numerical modeling technique based on the Finite Element Method (FEM) can adequately predict the mechanical behavior of recycled aggregate concrete (RAC) reinforced with steel fibers applied to rigid pavement slabs and reinforced flat slabs, thus contributing to the study of the reuse of CDW. The threedimensional modeling of the slabs uses unidimensional finite elements to discretize the bars and steel fibers, which are coupled through the coupling finite elements (CFEs) in the tetrahedral elements mesh of the concrete matrix, considering the loss of adhesion between the concrete and the fibers, as well as the concrete tensile damage model and the constitutive models of its reinforcements, emphasizing that concrete is modeled as a homogeneous material (macroscopic scale). The applied methodology proved to be adequate, as the numerical results were similar to the experimental ones, indicating that the increase in the percentage of replacement of natural aggregates by recycled ones decreased the mechanical resistance capacity, ductility and energy dissipation of the concrete slabs, but these effects were reversed with the addition of steel fibers in the structure. Different values of compressive strength of concrete, whose crushing originates the recycled aggregates, also influenced the mechanical behavior of the rigid pavement slabs.
The civil construction area is in constant evolution and even though it provides very positive effects, there is a not very pleasant consequence, represented by the increase in the amount of construction and demolition waste (CDW). Usually, the solution found for the disposal of these residues consists of dumping them in landfills or dumps and even in vacant lots and regions close to rivers and roads. This fact contributes to the generation of environmental damage, which is why the use of CDW as recycled aggregate becomes a sustainable solution to this problem. In this context, this research aims to determine if the numerical modeling technique based on the Finite Element Method (FEM) can adequately predict the mechanical behavior of recycled aggregate concrete (RAC) reinforced with steel fibers applied to rigid pavement slabs and reinforced flat slabs, thus contributing to the study of the reuse of CDW. The threedimensional modeling of the slabs uses unidimensional finite elements to discretize the bars and steel fibers, which are coupled through the coupling finite elements (CFEs) in the tetrahedral elements mesh of the concrete matrix, considering the loss of adhesion between the concrete and the fibers, as well as the concrete tensile damage model and the constitutive models of its reinforcements, emphasizing that concrete is modeled as a homogeneous material (macroscopic scale). The applied methodology proved to be adequate, as the numerical results were similar to the experimental ones, indicating that the increase in the percentage of replacement of natural aggregates by recycled ones decreased the mechanical resistance capacity, ductility and energy dissipation of the concrete slabs, but these effects were reversed with the addition of steel fibers in the structure. Different values of compressive strength of concrete, whose crushing originates the recycled aggregates, also influenced the mechanical behavior of the rigid pavement slabs.
Descrição
Palavras-chave
Comportamento mecânico, Lajes de pavimento rígido, Agregado reciclado, Fibras de aço, Elementos Finitos, Mechanical behavior, Rigid pavement slabs, Recycled aggregate, Steel fibers, Finite Elements