Ricardo A M Silveira | Universidade Federal de Ouro Preto (original) (raw)
Papers by Ricardo A M Silveira
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Rem: Revista Escola de Minas, 2013
Esse trabalho apresenta um estudo referente à análise da estabilidade e vibração não linear de pó... more Esse trabalho apresenta um estudo referente à análise da estabilidade e vibração não linear de pórticos de aço planos do tipo galpão. Especial atenção é voltada à influência do pré-carregamento estático nas frequências naturais e nos modos de vibração dessas estruturas. Nesse sentido, foi utilizada uma formulação não linear de elementos finitos de viga-coluna que permite considerar as ligações entre os membros estruturais como semirrígidas. Para resolver o problema de equilíbrio estático não linear, um processo incremental e iterativo do tipo Newton acoplado ao método do comprimento de arco é adotado. Uma vez obtida convergência em cada passo de carga, emprega-se o método de Jacobi, para se determinarem as frequências naturais e os modos de vibração da estrutura pré-carregada. Todo o processo de solução não linear adotado é detalhado em um algoritmo. A influência de um parâmetro geométrico (altura da tesoura) e outro físico (rigidez dos apoios) no comportamento do pórtico tipo galpã...
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Rem: Revista Escola de Minas, 2002
Esse trabalho fornece algumas formulações de elementos finitos circulares para análise de arcos e... more Esse trabalho fornece algumas formulações de elementos finitos circulares para análise de arcos e anéis. Atenção especial é dada ao cálculo da matriz de rigidez dos elementos finitos desenvolvidos, onde os efeitos das deformações de flexão, cisalhantes e de membrana são levados em consideração. O acoplamento desses efeitos permite a análise do comportamento de arcos esbeltos e espessos. No final do artigo, através da análise de problemas estruturais encontrados na literatura, pretende-se verificar a eficiência das formulações implementadas. O objetivo é conhecer a melhor modelagem numérica para obtenção dos deslocamentos e forças resultantes de sistemas estruturais curvos.
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Latin American Journal of Solids and Structures, 2018
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Structural Engineering and Mechanics, 2001
A numerical methodology is presented in this paper for the geometrically non-linear analysis of s... more A numerical methodology is presented in this paper for the geometrically non-linear analysis of slender uni-dimensional structural elements under unilateral contact constraints. The finite element method together with an updated Lagrangian formulation is used to study the structural system. The unilateral constraints are imposed by tensionless supports or foundations. At each load step, in order to obtain the contact regions, the equilibrium equations are linearized and the contact problem is treated directly as a minimisation problem with inequality constraints, resulting in a linear complementarity problem (LCP). After the resulting LCP is solved by Lemke’s pivoting algorithm, the contact regions are identified and the Newton-Raphson method is used together with path following methods to obtain the new contact forces and equilibrium configurations. The proposed methodology is illustrated by two examples and the
results are compared with numerical and experimental results found in literature.
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Steel & Composite Structures, 2010
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Rem: Revista Escola de Minas, 2005
Esse trabalho fornece um estudo sobre o comportamento inelástico de segunda ordem de estruturas m... more Esse trabalho fornece um estudo sobre o comportamento inelástico de segunda ordem de estruturas metálicas, tendo como base o emprego do método dos elementos finitos e do método da rótula plástica. Atenção especial é dada à formulação de um elemento finito híbrido, em especial da sua matriz de rigidez, que é modificada durante o processo de carregamento da estrutura, para incorporar os efeitos inelásticos da estrutura. O conceito da seção montada é introduzido juntamente com os fundamentos da abordagem plástica-refinada empregada. Ao final desse artigo, através da análise de vários problemas encontrados na literatura, verifica-se a eficácia, tanto da formulação inelástica desenvolvida, quanto das implementações computacionais realizadas.
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Mathematical Problems in Engineering, 2008
In this work, two numerical methodologies are proposed for the solution of unilateral contact pro... more In this work, two numerical methodologies are proposed for the solution of unilateral contact problems between a structural member (beam or arch) and an elastic foundation. In the first approach, the finite element method is used to discretize the structure and elastic foundation and the contact problem is formulated as a constrained optimization problem. Only the original variables of the problem are used, subjected to inequality constraints, and the relevant equations are written as a linear complementary problem (LCP). The second approach is based on the Ritz method, where the coordinates defining the limits of the contact regions are considered as additional variables of the problem. The contact problem here is treated as an unconstrained optimum design problem. These proposed methodologies are then tested and compared using results from specific problems involving structures under unilateral contact constraints.
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International Journal of Mechanical Sciences, 2010
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Revista IBRACON de Estruturas e Materiais, 2014
This work investigates the response of two reinforced concrete (RC) plane frames after the loss o... more This work investigates the response of two reinforced concrete (RC) plane frames after the loss of a column and their potential resistance for progressive collapse. Nonlinear dynamic analysis is performed using a multilayered Euler/Bernoulli beam element, including elasto-viscoplastic effects. The material nonlinearity is represented using one-dimensional constitutive laws in the material layers, while geometrical nonlinearities are incorporated within a corotational beam formulation. The frames were designed in accordance with the minimum requirements proposed by the reinforced concrete design/building codes of Europe (fib [1-2], Eurocode 2 [3]) and Brazil (NBR 6118 [4]). The load combinations considered for PC analysis follow the prescriptions of DoD [5]. The work verifies if the minimum requirements of the considered codes are sufficient for enforcing structural safety and robustness, and also points out the major differences in terms of progressive collapse potential of the corr...
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Latin American Journal of Solids and Structures, 2022
The present paper aims to test recent (Truly self-starting two sub-step method and three-paramete... more The present paper aims to test recent (Truly self-starting two sub-step method and three-parameter singlestep implicit method) and classical (Generalized-α, HHT-α, and WBZ-α methods) time integration methods using the geometrically nonlinear Positional Finite Element Method (PFEM). The numerical formulation is based on the total Lagrangian approach and uses the Hessian matrix to obtain the response. The mixed hardening inelastic model applied to PFEM is also presented. Two examples validate the time integration algorithms and the inelastic model. In the first example, the mixed hardening inelastic model is compared with the the bilinear stress-strain model and the elastic-perfectly plastic hinge model, and aspects such as amplitude decay and period elongation are discussed. In the second example, the implemented algorithms are verified in a severe geometrically nonlinear example, considering the influence of numerical dissipation, time interval, and the number of elements in the response. Results show the relevance of numerical damping for numerical stabilization and the good performance of the Generalized-α algorithm.
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Computer Methods in Applied Mechanics and Engineering, 1993
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Revista de Estrutura do Aço, Apr 1, 2019
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Estudos Transdisciplinares nas Engenharias
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Nonlinear Dynamics
Pyramidal space trusses are currently used in many present-day engineering applications, either a... more Pyramidal space trusses are currently used in many present-day engineering applications, either as main parts or as a constitutive element. The present work studies, using a corotational finite element formulation considering large displacements and rotations and an elastoplastic material behavior with isotropic strain hardening, the nonlinear dynamic behavior of a pyramidal space truss. A bilinear hysteretic model with kinematic hardening is used to represent thematerial nonlinearity. An appropriate strain measure in such processes is the logarithmic strain. However, the engineering strain and the quadratic strain measures have been usually used to perform the elastic stability analysis of such structures. Thus, in the present work results using both the quadratic and the logarithmic strainmeasures are compared. First, the static nonlinear behavior is investigated in order to understand the influence of nonlinearities and static preload on the potential energy landscape, which controls the dynamics of the truss. These structures exhibit a two-well potential function that leads to coexisting in-well and cross-well solution branches, resulting in several coexisting periodic, quasi-periodic and chaotic attractors. The influence of the constitutive law, strain measure, truss geometry and support flexibility on the static stability is then investigated. Based on these results, a detailed parametric analysis of the nonlinear truss response under vertical load is conducted using bifurcations diagrams of the Poincaré map to investigate the effect of the constitutive law, strain measure, truss geometry and load control parameters on the bifurcation scenario, coexisting attractors and dynamic buckling loads. The effect of the strain hardening parameter is particularly emphasized, allowing a more comprehensive picture of the dynamical behavior exhibited by the bistable system. Properties of the response are further illustrated by samples of time and phase plane responses and the related Poincaré section plots. In addition to known behaviors, a rich class of solutions and bifurcations, including jump phenomena, symmetry-breaking, period-doubling cascades, fold and chaos is detected.
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MATEC Web of Conferences
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Rem: Revista Escola de Minas, 2013
Esse trabalho apresenta um estudo referente à análise da estabilidade e vibração não linear de pó... more Esse trabalho apresenta um estudo referente à análise da estabilidade e vibração não linear de pórticos de aço planos do tipo galpão. Especial atenção é voltada à influência do pré-carregamento estático nas frequências naturais e nos modos de vibração dessas estruturas. Nesse sentido, foi utilizada uma formulação não linear de elementos finitos de viga-coluna que permite considerar as ligações entre os membros estruturais como semirrígidas. Para resolver o problema de equilíbrio estático não linear, um processo incremental e iterativo do tipo Newton acoplado ao método do comprimento de arco é adotado. Uma vez obtida convergência em cada passo de carga, emprega-se o método de Jacobi, para se determinarem as frequências naturais e os modos de vibração da estrutura pré-carregada. Todo o processo de solução não linear adotado é detalhado em um algoritmo. A influência de um parâmetro geométrico (altura da tesoura) e outro físico (rigidez dos apoios) no comportamento do pórtico tipo galpã...
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Rem: Revista Escola de Minas, 2002
Esse trabalho fornece algumas formulações de elementos finitos circulares para análise de arcos e... more Esse trabalho fornece algumas formulações de elementos finitos circulares para análise de arcos e anéis. Atenção especial é dada ao cálculo da matriz de rigidez dos elementos finitos desenvolvidos, onde os efeitos das deformações de flexão, cisalhantes e de membrana são levados em consideração. O acoplamento desses efeitos permite a análise do comportamento de arcos esbeltos e espessos. No final do artigo, através da análise de problemas estruturais encontrados na literatura, pretende-se verificar a eficiência das formulações implementadas. O objetivo é conhecer a melhor modelagem numérica para obtenção dos deslocamentos e forças resultantes de sistemas estruturais curvos.
Bookmarks Related papers MentionsView impact
Latin American Journal of Solids and Structures, 2018
Bookmarks Related papers MentionsView impact
Structural Engineering and Mechanics, 2001
A numerical methodology is presented in this paper for the geometrically non-linear analysis of s... more A numerical methodology is presented in this paper for the geometrically non-linear analysis of slender uni-dimensional structural elements under unilateral contact constraints. The finite element method together with an updated Lagrangian formulation is used to study the structural system. The unilateral constraints are imposed by tensionless supports or foundations. At each load step, in order to obtain the contact regions, the equilibrium equations are linearized and the contact problem is treated directly as a minimisation problem with inequality constraints, resulting in a linear complementarity problem (LCP). After the resulting LCP is solved by Lemke’s pivoting algorithm, the contact regions are identified and the Newton-Raphson method is used together with path following methods to obtain the new contact forces and equilibrium configurations. The proposed methodology is illustrated by two examples and the
results are compared with numerical and experimental results found in literature.
Bookmarks Related papers MentionsView impact
Steel & Composite Structures, 2010
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Rem: Revista Escola de Minas, 2005
Esse trabalho fornece um estudo sobre o comportamento inelástico de segunda ordem de estruturas m... more Esse trabalho fornece um estudo sobre o comportamento inelástico de segunda ordem de estruturas metálicas, tendo como base o emprego do método dos elementos finitos e do método da rótula plástica. Atenção especial é dada à formulação de um elemento finito híbrido, em especial da sua matriz de rigidez, que é modificada durante o processo de carregamento da estrutura, para incorporar os efeitos inelásticos da estrutura. O conceito da seção montada é introduzido juntamente com os fundamentos da abordagem plástica-refinada empregada. Ao final desse artigo, através da análise de vários problemas encontrados na literatura, verifica-se a eficácia, tanto da formulação inelástica desenvolvida, quanto das implementações computacionais realizadas.
Bookmarks Related papers MentionsView impact
Mathematical Problems in Engineering, 2008
In this work, two numerical methodologies are proposed for the solution of unilateral contact pro... more In this work, two numerical methodologies are proposed for the solution of unilateral contact problems between a structural member (beam or arch) and an elastic foundation. In the first approach, the finite element method is used to discretize the structure and elastic foundation and the contact problem is formulated as a constrained optimization problem. Only the original variables of the problem are used, subjected to inequality constraints, and the relevant equations are written as a linear complementary problem (LCP). The second approach is based on the Ritz method, where the coordinates defining the limits of the contact regions are considered as additional variables of the problem. The contact problem here is treated as an unconstrained optimum design problem. These proposed methodologies are then tested and compared using results from specific problems involving structures under unilateral contact constraints.
Bookmarks Related papers MentionsView impact
International Journal of Mechanical Sciences, 2010
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Revista IBRACON de Estruturas e Materiais, 2014
This work investigates the response of two reinforced concrete (RC) plane frames after the loss o... more This work investigates the response of two reinforced concrete (RC) plane frames after the loss of a column and their potential resistance for progressive collapse. Nonlinear dynamic analysis is performed using a multilayered Euler/Bernoulli beam element, including elasto-viscoplastic effects. The material nonlinearity is represented using one-dimensional constitutive laws in the material layers, while geometrical nonlinearities are incorporated within a corotational beam formulation. The frames were designed in accordance with the minimum requirements proposed by the reinforced concrete design/building codes of Europe (fib [1-2], Eurocode 2 [3]) and Brazil (NBR 6118 [4]). The load combinations considered for PC analysis follow the prescriptions of DoD [5]. The work verifies if the minimum requirements of the considered codes are sufficient for enforcing structural safety and robustness, and also points out the major differences in terms of progressive collapse potential of the corr...
Bookmarks Related papers MentionsView impact
Latin American Journal of Solids and Structures, 2022
The present paper aims to test recent (Truly self-starting two sub-step method and three-paramete... more The present paper aims to test recent (Truly self-starting two sub-step method and three-parameter singlestep implicit method) and classical (Generalized-α, HHT-α, and WBZ-α methods) time integration methods using the geometrically nonlinear Positional Finite Element Method (PFEM). The numerical formulation is based on the total Lagrangian approach and uses the Hessian matrix to obtain the response. The mixed hardening inelastic model applied to PFEM is also presented. Two examples validate the time integration algorithms and the inelastic model. In the first example, the mixed hardening inelastic model is compared with the the bilinear stress-strain model and the elastic-perfectly plastic hinge model, and aspects such as amplitude decay and period elongation are discussed. In the second example, the implemented algorithms are verified in a severe geometrically nonlinear example, considering the influence of numerical dissipation, time interval, and the number of elements in the response. Results show the relevance of numerical damping for numerical stabilization and the good performance of the Generalized-α algorithm.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Computer Methods in Applied Mechanics and Engineering, 1993
Bookmarks Related papers MentionsView impact
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Revista de Estrutura do Aço, Apr 1, 2019
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Estudos Transdisciplinares nas Engenharias
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Nonlinear Dynamics
Pyramidal space trusses are currently used in many present-day engineering applications, either a... more Pyramidal space trusses are currently used in many present-day engineering applications, either as main parts or as a constitutive element. The present work studies, using a corotational finite element formulation considering large displacements and rotations and an elastoplastic material behavior with isotropic strain hardening, the nonlinear dynamic behavior of a pyramidal space truss. A bilinear hysteretic model with kinematic hardening is used to represent thematerial nonlinearity. An appropriate strain measure in such processes is the logarithmic strain. However, the engineering strain and the quadratic strain measures have been usually used to perform the elastic stability analysis of such structures. Thus, in the present work results using both the quadratic and the logarithmic strainmeasures are compared. First, the static nonlinear behavior is investigated in order to understand the influence of nonlinearities and static preload on the potential energy landscape, which controls the dynamics of the truss. These structures exhibit a two-well potential function that leads to coexisting in-well and cross-well solution branches, resulting in several coexisting periodic, quasi-periodic and chaotic attractors. The influence of the constitutive law, strain measure, truss geometry and support flexibility on the static stability is then investigated. Based on these results, a detailed parametric analysis of the nonlinear truss response under vertical load is conducted using bifurcations diagrams of the Poincaré map to investigate the effect of the constitutive law, strain measure, truss geometry and load control parameters on the bifurcation scenario, coexisting attractors and dynamic buckling loads. The effect of the strain hardening parameter is particularly emphasized, allowing a more comprehensive picture of the dynamical behavior exhibited by the bistable system. Properties of the response are further illustrated by samples of time and phase plane responses and the related Poincaré section plots. In addition to known behaviors, a rich class of solutions and bifurcations, including jump phenomena, symmetry-breaking, period-doubling cascades, fold and chaos is detected.
Bookmarks Related papers MentionsView impact
MATEC Web of Conferences
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