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Huespe, Alfredo Edmundo - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of the fracture process in reinforced concrete by means of a continuum strong discontinuity approach. Part I: formulation
    2010
    Co-Authors: Linero Segrera, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional. // Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs.Postprint (published version

  • Simulación numérica del proceso de fractura en concreto reforzado mediante la metodología de discontinuidades fuertes de continuo: Parte I: formulación
    'Universidad Nacional de Colombia', 2010
    Co-Authors: Linero, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs.En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional

  • Numerical modelling of the fracture process in reinforced concrete by means of a continuum strong discontinuity approach. Part I: formulation
    2010
    Co-Authors: Linero Segrera, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional. // Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs

Linero Segrera, Dorian Luis - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of the fracture process in reinforced concrete by means of a continuum strong discontinuity approach. Part I: formulation
    2010
    Co-Authors: Linero Segrera, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional. // Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs.Postprint (published version

  • Numerical modelling of the fracture process in reinforced concrete by means of a continuum strong discontinuity approach. Part I: formulation
    2010
    Co-Authors: Linero Segrera, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional. // Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs

  • Simulación numérica del proceso de fractura en concreto reforzado mediante la metodología de discontinuidades fuertes de continuo. Parte I: formulación Numerical modeling of the fracture process in reinforced concrete by means of the continuum strong discontinuity approach. Part I: formulation
    Universidad Nacional de Colombia, 2010
    Co-Authors: Huespe Alfredo E., Oliver Javier, Linero Segrera, Dorian Luis
    Abstract:

    En general, las estructuras de concreto reforzado como vi- gas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplica- ción de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es descri- bir el proceso de fractura en elementos de concreto reforza- do a partir de la fracción volumétrica del concreto y del ace- ro. El modelo utiliza un campo enriquecido de la deforma- ción para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodolo- gía de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una ma- triz de concreto y uno o dos paquetes de barras de acero or- togonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La ac- ción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que rela- cionan el esfuerzo y la deformación de los materiales com- ponentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los e- lementos finitos, dado que permanecen muchas característi- cas del procedimiento numérico no lineal convencional. Asi- mismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de e- lementos finitos de cada material componente y de sus efec- tos de interacción, reduciendo así el costo computacional.Reinforced concrete structures generally refers to beams, co- lumns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the for- mulation of a numerical model aimed at describing the frac- ture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are re- presented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite e- lement mesh having to be constructed for each component material and its interAction effects and reducing computa- tional costs

Mihaylov Boyan - One of the best experts on this subject based on the ideXlab platform.

  • Direct Evaluation of Shear Carrying Mechanisms in Reinforced Concrete Deep Beams
    2021
    Co-Authors: Palipana Dhanushka, Trandafir Alexandru, Mihaylov Boyan, Proestos Giorgio
    Abstract:

    Reinforced concrete deep beams, such as hammerhead piers, corbels and transfer girders, are common elements found in a variety of structures. These members are characterized by relatively small shear span-to-depth ratios and are often shear critical. The Two-Parameter Kinematic Theory (2PKT) has been shown to successfully predict the complete response of these members, including the shear strength and post-peak response. This modelling approach proposes that the shear carried in deep beams is the summation of the shear transfer by the critical loading zone, by aggregate interlock, by the transverse reinforcement and by Dowel Action. This paper uses experimental data from five recently conducted large-scale deep beam tests to directly quantify the shear transfer mechanisms of deep beams. Digital Image Correlation (DIC) equipment was used to measure the displacements and strains in the uncracked critical loading zone. A refined grid of infrared position tracking targets is used to measure the global deformations. Together these measurements are used to back-calculate the stresses in the critical loading zone, the aggregate interlock along the critical crack, the stress in the transverse reinforcement and the Dowel Action of the longitudinal reinforcement. The summation of the shear transfer along the critical shear crack is then determined and compared with the experimentally applied load. The paper discusses the detailed constitutive models used to translate local strains to stresses in the critical loading zone and along the shear crack. A comparison of the different models is conducted. The results indicate that reasonable estimates of the applied load are obtainable using several of the constitutive models studied. The paper also discusses the significance of each shear transfer mechanism in deep beams.Peer reviewe

  • Evaluating the Shear Resistance of Deep Beams Loaded or Supported by Wide Elements
    2021
    Co-Authors: Proestos Giorgio, Palipana Dhanushka, Mihaylov Boyan
    Abstract:

    It is common in concrete structures to encounter deep beams that are loaded or supported by wide elements such as shear walls in buildings and large piers in bridges. This type of boundary condition results in stress concentrations at the edges of the loading/supporting elements, and this in turn results in steep diagonal cracks and concentrated diagonal struts. In this study the shear strength of deep beams affected by stress concentrations is studied in detail with two methods: a two-parameter kinematic theory (2PKT) and nonlinear finite element models (FEM). It is shown that, with appropriate simple modifications to account for the loading/support conditions and the Dowel Action of the longitudinal web reinforcement, the 2PKT captures well the shear strength of 10 tests specimens from the literature. In addition to similarly adequate shear strength predictions, the more complex FEM also captures the strain concentrations measured in the tests. It is recognized that FEM analyses and detailed experimental measurements need to be used to ultimately develop a rational approach for evaluating the stress concentrations for the needs of both kinematic and strut-and-tie modelling.Peer reviewe

  • Evaluating the Shear Resistance of Deep Beams Loaded or Supported by Wide Elements
    'Elsevier BV', 2020
    Co-Authors: Proestos Giorgio, Palipana Dhanushka, Mihaylov Boyan
    Abstract:

    peer reviewedaudience: researcher, professional, studentIt is common in concrete structures to encounter deep beams that are loaded or supported by wide elements such as shear walls in buildings and large piers in bridges. This type of boundary condition results in stress concentrations at the edges of the loading/supporting elements, and this in turn results in steep diagonal cracks and concentrated diagonal struts. In this study the shear strength of deep beams affected by stress concentrations is studied in detail with two methods: a two-parameter kinematic theory (2PKT) and nonlinear finite element models (FEM). It is shown that, with appropriate simple modifications to account for the loading/support conditions and the Dowel Action of the longitudinal web reinforcement, the 2PKT captures well the shear strength of 10 tests specimens from the literature. In addition to similarly adequate shear strength predictions, the more complex FEM also captures the strain concentrations measured in the tests. It is recognized that FEM analyses and detailed experimental measurements need to be used to ultimately develop a rational approach for evaluating the stress concentrations for the needs of both kinematic and strut-and-tie modelling

  • A Kinematic Approach for the Shear Strength of Short FRC Coupling Beams
    'Elsevier BV', 2019
    Co-Authors: Mihaylov Boyan
    Abstract:

    peer reviewedaudience: researcher, professional, studentShort coupling beams are susceptible to brittle shear failures that are typically suppressed with dense transverse and/or diagonal reinforcement. To reduce the amount of shear reinforcement and improve the service behavior of the beam, researchers have proposed a solution with steel fiber-reinforced concrete (FRC). However, while this solution is promising, there are no sufficiently simple mechanical models capable of capturing the shear strength and displacement capacity of short FRC coupling beams without diagonal reinforcement. This paper proposes such a model based on first principles: kinematics, equilibrium, and constitutive relationships for the mechanisms of shear resistance. The model accounts in an explicit manner for five shear mechanisms across the critical shear cracks: diagonal compression in the critical loading zones, aggregate interlock, tension in the stirrups and in the steel fibres, and Dowel Action of the longitudinal reinforcement. These mechanisms are predicted and the results are compared to 20 tests from the literature as well as to FEM predictions. It is shown that the proposed approach models well the effect of beam aspect ratio, concrete strength, stirrup ratio, and amount of steel fibres. Furthermore, the model is used to develop relationships outlining the effectiveness of steel fibres to reduce conventional stirrup reinforcement in coupling beams with various properties

  • A Kinematic Approach for the Shear Strength of Short FRC Coupling Beams
    2019
    Co-Authors: Mihaylov Boyan
    Abstract:

    Short coupling beams are susceptible to brittle shear failures that are typically suppressed with dense transverse and/or diagonal reinforcement. To reduce the amount of shear reinforcement and improve the service behavior of the beam, researchers have proposed a solution with steel fiber-reinforced concrete (FRC). However, while this solution is promising, there are no sufficiently simple mechanical models capable of capturing the shear strength and displacement capacity of short FRC coupling beams without diagonal reinforcement. This paper proposes such a model based on first principles: kinematics, equilibrium, and constitutive relationships for the mechanisms of shear resistance. The model accounts in an explicit manner for five shear mechanisms across the critical shear cracks: diagonal compression in the critical loading zones, aggregate interlock, tension in the stirrups and in the steel fibres, and Dowel Action of the longitudinal reinforcement. These mechanisms are predicted and the results are compared to 20 tests from the literature as well as to FEM predictions. It is shown that the proposed approach models well the effect of beam aspect ratio, concrete strength, stirrup ratio, and amount of steel fibres. Furthermore, the model is used to develop relationships outlining the effectiveness of steel fibres to reduce conventional stirrup reinforcement in coupling beams with various properties.Peer reviewe

Oliver Olivella Xavier - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of the fracture process in reinforced concrete by means of a continuum strong discontinuity approach. Part I: formulation
    2010
    Co-Authors: Linero Segrera, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional. // Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs.Postprint (published version

  • Simulación numérica del proceso de fractura en concreto reforzado mediante la metodología de discontinuidades fuertes de continuo: Parte I: formulación
    'Universidad Nacional de Colombia', 2010
    Co-Authors: Linero, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs.En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional

  • Numerical modelling of the fracture process in reinforced concrete by means of a continuum strong discontinuity approach. Part I: formulation
    2010
    Co-Authors: Linero Segrera, Dorian Luis, Oliver Olivella Xavier, Huespe, Alfredo Edmundo
    Abstract:

    En general, las estructuras de concreto reforzado como vigas, columnas y muros están conformadas por entramados complejos de barras de acero embebidas en una matriz de concreto, las cuales exhiben múltiples fisuras ante la aplicación de cargas externas elevadas. Este artículo presenta la formulación de un modelo numérico cuyo objetivo es describir el proceso de fractura en elementos de concreto reforzado a partir de la fracción volumétrica del concreto y del acero. El modelo utiliza un campo enriquecido de la deformación para describir la formación y propagación de fisuras en un material compuesto, tal como lo establecen la metodología de discontinuidades fuertes de continuo y la teoría de mezclas. El material compuesto está constituido por una matriz de concreto y uno o dos paquetes de barras de acero ortogonales entre sí. El acero y el concreto se representan con modelos de plasticidad unidimensional y de daño escalar con tracción y compresión diferenciada, respectivamente. La acción pasador y los efectos del deslizamiento entre las barras y la matriz, se describen con modelos adicionales que relacionan el esfuerzo y la deformación de los materiales componentes. Finalmente, se concluye que el modelo propuesto se puede implementar con facilidad en el método de los elementos finitos, dado que permanecen muchas características del procedimiento numérico no lineal convencional. Asimismo, el modelo permite analizar el problema en la escala macroscópica, lo cual elude la construcción de mallas de elementos finitos de cada material componente y de sus efectos de interacción, reduciendo así el costo computacional. // Reinforced concrete structures generally refers to beams, columns and walls which are constituted by complex lattices of steel bars embedded in a concrete matrix, exhibiting multiple cracks due to high external loads. This paper presents the formulation of a numerical model aimed at describing the fracture process in reinforced concrete, from the volumetric ratio of concrete and steel. Crack formation and propagation in a composite material is described in the model by an enhanced strain field, such as that established in the continuum strong discontinuity approach and mixture theory. The composite material is constituted by a concrete matrix and one or two steel bar orthogonal packages. The steel and concrete are represented by a one-dimensional plasticity model and a scalar damage model having different tension and compression strength, respectively. The Dowel Action and the bond-slip effects between the bars and the matrix are described with additional models relating component material stress and strain. It is concluded that the proposed model can easily be implemented in the finite element method, due to several conventional nonlinear numerical process characteristics which remain. The model would also allow the problem to be analysed at macroscopic scale, thereby avoiding a finite element mesh having to be constructed for each component material and its interAction effects and reducing computational costs

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  • Shear-stress transfer across a crack in steel fibre-reinforced concrete
    Cement and Concrete Composites, 2017
    Co-Authors: Tim Soetens, Stijn Matthys
    Abstract:

    Abstract The ability of cracked reinforced concrete to transfer shear stresses is of major importance for concrete members designed to sustain high shear forces. Thereby, the maximum shear capacity is mainly affected by the aggregate interlock mechanism, the Dowel Action of longitudinal reinforcement, the restraining Action of stressed reinforcement crossing the crack interface and the possible presence of stirrups. In case of steel fibre reinforced concrete (SFRC), where fibres are used to replace either completely or partially traditional stirrups, research has proven that the direct shear transfer capacity of cracked concrete is increased significantly by using fibres. By means of 69 direct shear tests, the shear-friction behaviour of SFRC with or without confining pressure has been studied further and existing empirical formulations have been checked. Since these models only provide a maximum shear strength, a more fundamental approach to model the direct shear behaviour of cracked SFRC is proposed in this paper. This model deals with the fibre-matrix interAction by means of fibre pull-out and aggregate interlock, as a function of the shear crack opening behaviour (i.e. combined opening and slipping).