EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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14 resultados
Resultados da Pesquisa
Item An efficient inelastic approach using SCM/RPHM coupling to study reinforced concrete beams, columns and frames under fire conditions.(2020) Pires, Dalilah; Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Rocha, Paulo Anderson SantanaThis work has as its main objective the study of the behavior of reinforced concrete beams, columns and structural frames in a fire situation. To do so an efficient numerical formulation was developed, implemented and evaluated. When exposed to high temperatures, the characteristics of the materials deteriorate, resulting in a considerable loss of strength and stiffness of the structure. The CS-ASA (Computational System for Advanced Structural Analysis) was used to achieve the objective. This computer system was expanded for advanced analysis of structures in fire conditions, taking advantage of the existing features and adding new ones. Two new computational modules were created: CS-ASA/FA (Fire Analysis) and CS-ASA/FSA (Structural Fire Analysis). The first one was used to determine the temperature field in the structural elements’ cross-section through thermal analysis by the Finite Element Method (FEM) in permanent and transient regimes. The second was created to perform the second-order inelastic analysis of structures under fire using the FEM formulations based on the Refined Plastic Hinge Method (RPHM) and the Strain Compatibility Method (SCM) coupling, which can be considered a unique feature of the present study. The use of SCM allows for a more realistic analysis against the design codes prescriptions. Consequently, even under high temperatures, SCM is used for evaluation of both bearing capacity and stiffness parameters. The results of the nonlinear analysis in a fire situation for eight structural elements and systems with different geometries, boundary, heating and loading conditions are in good agreement with the numerical and experimental results found in the literature.Item Thermo-structural analysis of reinforced concrete beams.(2019) Maximiano, Dalilah Pires; Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Rocha, Paulo Anderson SantanaThe objective of this study is to simulate the behavior of reinforced concrete beams in fire situation. In order to achieve this objective, advanced numerical formulations were developed, implemented and evaluated. When exposed to high temperatures, the properties of the material deteriorate, resulting in the loss of strength and stiffness. To achieve the goal, two new modules within the Computational System for Advanced Structural Analysis were created: Fire Analysis and Fire Structural Analysis. The first one aims to determine the temperature field in the cross section of structural elements through thermal analysis by using the Finite Element Method (FEM). The second was designed to perform the second-order inelastic analysis of structures under fire using FEM formulations based on the Refined Plastic Hinge Method coupled with the Strain Compatibility Method. The results obtained of the nonlinear analyses of two reinforced concrete beams under high temperature were compared with the numerical and experimental solutions available in literature and were highly satisfactory. These results also showed that the proposed numerical approach can be used to study the progressive collapse of other reinforced concrete structures in fire situation and extended to the numerical analysis of composite structures under fire condition.Item Análise e projeto de estruturas de concreto usando o modelo de bielas e tirantes via MEF : aplicação em blocos de fundação, consolos curtos, vigas-parede e sapatas rígidas.(2019) Lima, Miguel Angelo Araújo; Rocha, Paulo Anderson Santana; Silveira, Ricardo Azoubel da Mota; Silva, Kátia Inácio daNeste trabalho tem-se como objetivo realizar análises elásticolineares a partir de um programa computacional destinado à implementação numérica do Modelo de Bielas e Tirantes, utilizando-se uma formulação baseada no Método dos Elementos Finitos (MEF). Com este modelo é possível analisar o comportamento de elementos estruturais como blocos de fundação, consolos curtos e sapatas rígidas e realizar o dimensionamento das armaduras de aço, representar os valores de tensões, deformações e deslocamentos na região de uma viga representada como o Modelo de Bielas desenvolvido por Montoya et al. [1], além de modelar numericamente via MEF uma viga-parede com uma grande abertura, desenvolvida por Schlaich et al. [2]. Com o fim de validar as implementações numéricas, os resultados foram comparados com modelagens numéricas realizadas com o auxílio do software ANSYS 17 e com expressões normativas.Item Advanced inelastic analysis of steel structures at elevated temperatures by SCM/RPHM coupling.(2018) Barros, Rafael Cesário; Maximiano, Dalilah Pires; Silveira, Ricardo Azoubel da Mota; Lemes, Igor José Mendes; Rocha, Paulo Anderson SantanaWhen exposed to high temperatures, the structural members and frames have their bearing capacity compromised because the physical characteristics and material resistance used in the structures deteriorate during exposure to fire, resulting in a considerable loss of strength and stiffness. In this context, the present work carries out a whole thermomechanical analysis of steel members and frames using the Finite Element Method (FEM) inelastic formulation based on the Refined Plastic Hinge Method (RPHM) coupled with the Strain Compatibility Method (SCM). The use of SCM allows for a more realistic analysis against the design codes prescriptions. So even under high temperatures, SCM is used for both evaluation of bearing capacity and stiffness parameters. To do this, the steel behavior used in the structure numerical modeling must be described in a consistent manner through its constitutive relationship. A comparison of the results obtained here with the numerical and experimental results available in the literature suggest the effectiveness of coupling SCM/RPHM and that such a methodology can provide reliable analyses of steel members and frames subjected to high temperatures.Item Numerical analysis of RC plane structures : a concentrated nonlinear effect approach.(2018) Lemes, Igor José Mendes; Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Silva, Andréa Regina Dias da; Rocha, Paulo Anderson SantanaThe present work aims to study the nonlinear behavior of reinforced concrete structures via Refined Plastic Hinge Method (RPHM). Pseudo-springs are used at the finite element ends, where the gradual loss of stiffness is determined by the combination of the normal force and bending moment (NM) in the cross section. The limiting of the uncracked, elastic and plastic regimes is done in the NM diagram. The concrete cracking is explicitly simulated with two approaches to calculate the effective moment of inertia of the cross section. The displacement-based formulation is referenced to the co-rotational system and coupled with continuation strategies to allow to overcome the possible critical points in the equilibrium paths. For validation of the numerical simulations, the results found with the proposed formulation are confronted with experimental and numerical data present in literature.Item Thermal analysis of steel-concrete composite cross sections via CS-ASA/FA.(2018) Maximiano, Dalilah Pires; Barros, Rafael Cesário; Rocha, Paulo Anderson Santana; Silveira, Ricardo Azoubel da MotaWhen exposed to high temperatures, such as in a fire situation, the physical and resistance characteristics of the materials employed in the structure deteriorate as the temperature increases. This fact promotes a considerable loss in the bearing capacity and stiffness of the structural system. The verification of a structure exposed to fire depends primarily and principally on the thermal analysis of the cross section of the structural element. This analysis permits determination of the temperature variation or temperature range in the element from the boundary conditions provided by the fire model adopted. As such, this study had the objective of performing a thermal analysis in a transient regime by means of a finite element method on steel-concrete composite cross sections that are employed in civil construction through use of the Computational System for Advanced Structural Analysis/Fire Analysis (CS-ASA/FA). Two cross sections are analyzed and the results obtained were satisfactory. In addition, different iterative solution processes were adopted in the analysis. Parametric studies were also performed related to the mesh variation of the finite elements and time increase. From the results, it was possible to conclude that CS-ASA/FA can supply the necessary information when a thermo-structural analysis is performed for the evaluation of strength and stiffness losses of the structural material when exposed to fire.Item Estudo do desempenho de vigas em situação de incêndio a partir do modelo de fibras.(2017) Rocha, Paulo Anderson Santana; Silva, Kátia Inácio daNeste trabalho apresenta-se a análise numérica de vigas de concreto armado de seção retangular e T e de vigas mistas de aço e concreto submetidas a altas temperaturas. Para a obtenção dos resultados numéricos, os quais se referem às relações momento x curvatura para diferentes temperaturas, bem como os valores máximos atingidos para os momentos fletores, utilizou-se o método ou modelo de fibras, sendo as relações constitutivas dos materiais (concreto e aço) definidas a partir das considerações do EUROCODE 2 parte 1.2 e da ABNT NBR 15200. A partir dos resultados obtidos, os quais são comparados com as respostas de expressões analíticas definidas pela ABNT NBR 6118 e pela ABNT NBR 8800, é possível se identificar a resistência residual da estrutura à medida que o tempo de exposição ao fogo aumenta e também demonstrar a redução efetiva de sua rigidez.Item Estudo numérico comparativo de metodologias para a degradação da rigidez à flexão no contexto do método da rótula plástica refinado.(2016) Lemes, Igor José Mendes; Silva, Andréa Regina Dias da; Silveira, Ricardo Azoubel da Mota; Rocha, Paulo Anderson SantanaItem Análise termomecânica de estruturas de aço via acoplamento MCD/MRPR.(2016) Barros, Rafael Cesário; Pires, Dalilah; Lemes, Igor José Mendes; Rocha, Paulo Anderson Santana; Silveira, Ricardo Azoubel da MotaQuando expostos à temperatura elevada, os elementos estruturais têm sua capacidade resistente comprometida, pois as características físicas e de resistência dos materiais empregados nas estruturas se deterioram com o aumento de temperatura. Nesse contexto, o presente trabalho tem como objetivo apresentar um novo módulo computacional, denominado aqui CS-ASA/FSA, capaz de realizar a análise numérica de estruturas de aço sujeitas à temperaturas elevadas. Esse módulo utiliza o Método dos Elementos Finitos (MEF) e a análise inelástica é baseada no Método da Rótula Plástica Refinado (MRPR) acoplado ao Método da Compatibilidade de Deformações (MCD). Esse último método foi adotado para avaliar tanto a capacidade resistente da seção transversal, quanto as rigidezes axial e à flexão de estruturas de aço sob elevadas temperaturas. A construção da relação momentocurvatura se torna essencial para tal avaliação. Por fim, os resultados obtidos são comparados aos numéricos e experimentais encontrados na literatura.Item Determinação da capacidade resistente de elementos estruturaismistos através do método da rótula plástica refinado.(2017) Lemes, Igor José Mendes; Silva, Andréa Regina Dias da; Silveira, Ricardo Azoubel da Mota; Rocha, Paulo Anderson Santana; https://doi.org/10.1016/j.rimni.2015.10.003