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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10 resultados
Resultados da Pesquisa
Item Advanced numerical study of composite steel-concrete structures at high temperature.(2021) Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Maximiano, Dalilah Pires; Lemes, Igor José MendesThe composite steel-concrete structures use has several advantages, such as the reduction of cross-sectional dimensions and weight of the structure, which is one of the main reasons for it is use today. However, under fire situation, the material and mechanical properties changes, causing significant strength and stiffness loss as a result of temperature rise. In this work, the temperature influence on the behavior of composite steel-concrete structures is studied through an inelastic second order (ISO) numerical investigation. For this, two computational modules, CS-ASA/FA and CS-ASA/FSA are developed and adapted for the study of composite structures in fire. The first module calculates the temperature field in any cross-section. The second module performs the ISO analysis through the coupling between the Refined Plastic Hinge Method (RPHM) and the Strain Compatibility Method (MCD). In this way, the evolution of the temperature in cross-sec- tions, the interaction diagrams between axial force and bending moment and the structures equi- librium path as a function of the time in fire are presented for composite steel-concrete beams, columns and frames. The proposed numerical methodology success is proved by comparison with experimental and numerical responses available in the literature.Item Concentrated approaches for nonlinear analysis of composite beams with partial interaction.(2021) Carvalho, Tawany Aparecida de; Lemes, Igor José Mendes; Silveira, Ricardo Azoubel da Mota; Dias, Luís Eduardo Silveira; Barros, Rafael CesárioTwo plane displacement-based formulations with concentrated nonlinear effects for numerical analysis of composite beams are presented here. The effects of geometric nonlinearity, plasticity and partial shear connection are considered. In these two approaches, the co-rotational system is defined to allow large displacements and rotations in the numerical model. The first formulation is based to Strain Compatibility Method, where the sections strains are explicitly evaluated as well as the slipping at the steel-concrete interface. Thus, the axial and flexural stiffness of the cross section is determined in each step of the incremental-iterative process. The second methodology considers rotational pseudo-springs at the finite elements ends to simulate of plasticity. Further- more, the effects of partial interaction can not be simulated by the inherently rotational behavior of the pseudo-springs. Thus, the cracking and partial interaction effects are approached through effective moment of inertia defined by normative criteria. Four composite beams are simulated with these two formulations and compared by the load-displacements paths. In all numerical re- sult findings these formulations are closed and accurate to the experimental data presented in lit- erature.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 Avaliação numérica do comportamento não linear e resistência de estruturas mistas de aço e concreto em situação de incêndio.(2021) Barros, Rafael Cesário; Silveira, Ricardo Azoubel da Mota; Silveira, Ricardo Azoubel da Mota; Chiorean, Cosmin-Gruia; Landesmann, Alexandre; Carvalho, Hermes; Maximiano, Dalilah PiresA presente pesquisa tem como objetivo principal a avaliação numérica do desempenho de estruturas mistas de aço-concreto em situação de incêndio. A capacidade resistente dos materiais que compõem as vigas, colunas e pórticos mistos, no caso o aço e o concreto, fica comprometida quando expostos a condição de elevadas temperaturas, uma vez que suas características físicas e de resistência se deterioram em função da elevação da temperatura. Desse modo, os dois módulos computacionais, CS-ASA/FA (Computational System for Advanced Structural Analysis/Fire Analysis) e CS-ASA/FSA (Computational System for Advanced Structural Analysis/Fire Structural Analysis) são desenvolvidos e adaptados para a análise não linear de estruturas mistas sob temperaturas elevadas. O primeiro módulo calcula o campo de temperatura em seções transversais quaisquer de aço, concreto armado e mistas, de onde se pode obter também a degradação das propriedades desses materiais expostos ao fogo. O segundo é desenvolvido para realizar análises inelástica de segunda ordem (AISO) de estruturas em situação de incêndio. No contexto da AISO via método dos elementos finitos (MEF), é empregado uma formulação corrotacional para acompanhar os grandes deslocamentos e rotações do sistema estrutural. Já o comportamento elasto-plástico do material é simulado através do acoplamento do Método da Rótula Plástica Refinado (MRPR) com o Método da Compatibilidade de Deformações (MCD). A metodologia numérica proposta é avaliada e testada com sucesso na análise de vigas, pilares e pórticos planos de aço-concreto em situação de incêndio utilizando os resultados experimentais e numéricos disponíveis na literatura. Finalmente, o estudo numérico é complementado com a AISO de arcos de aço e estruturas de concreto armado em situação de incêndio.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 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 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 Avaliação numérica avançada do desempenho de estruturas de aço sob temperaturas elevadas.(2016) Barros, Rafael CesárioEsta dissertação tem como objetivo a avaliação numérica do desempenho de estruturas de aço quando submetidas à situação de incêndio. Quando expostos à temperaturas elevadas, os elementos estruturais tem sua capacidade resistente comprometida, pois as características físicas e de resistência dos materiais empregados nas estruturas se deterioram com o aumento de temperatura, acarretando numa perda considerável da sua capacidade resistente e da sua rigidez. Neste cenário, foram desenvolvidos dois módulos adicionais ao programa CS-ASA: o primeiro destinado à obtenção do campo de temperaturas a nível de seção transversal de elementos em aço; já o segundo é responsável pela análise numérica de segunda ordem inelástica de estruturas de aço sujeitas à temperaturas elevadas. Um elemento finito geometricamente não linear é utilizado na discretização do sistema termoestrutural e o modelo de fibras é usado na discretização da seção transversal do perfil metálico. O estudo do comportamento inelástico dos elementos estruturais seguem os fundamentos básicos propostos pelo Método da Rótula Plástica Refinado (MRPR) acoplado ao Método da Compatibilidade de Deformações (MCD). Por fim, os exemplos são apresentados em três grupos: análise térmica; curvas de interação normal-momento; e análise termomecânica de vigas, pilares e pórticos. Os resultados obtidos são comparados com os resultados da literatura, apresentando boa concordância para todos os casos.