Mestrado em Engenharia Civil
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Navegando Mestrado em Engenharia Civil por Assunto "Aço - Estruturas"
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- ItemAnálise da influência do diafragma externo na ligação entre viga de seção I e pilar tubular de seção circular(Universidade Federal do Espírito Santo, 2018-08-09) Orrico, Ana Carolina Scampini Rangel; Azevedo, Macksuel Soares de; Ferreira, Walnório Graça; Munaiar Neto, JorgeThe use of external diaphragms in connections between I-beams and circular hollow section columns aims to improve efficiency of the transmission of forces and moments between these two elements. The study of diaphragms began in Japan in the 1970s, where theoretical work and experimental analysis of its application were made. In Brazil research dates to 2005, when Carvalho (2005) performed the first numerical analyzes of a connection both with and without the diaphragm. The Brazilian standard ANBT NBR 16239:2013 does not address the design of this type of connection, which is contemplated only by Kurobane (2004) in the Comité Internacional pour Le Développement et l’Etude de La Construction Tubulaire (CIDECT). The objective of this study is to analyze the behavior of external diaphragms in the connections between I-beams and circular hollow section columns. Numerical analysis was performed exploring a range of geometries for the external diaphragm and evaluating the effectiveness of the connection when both the beam and the column are loaded. The diaphragm proved to be an effective mechanism to increase the initial stiffness and the ultimate strength of the connection providing resistance gains ranging from 30 to 173%, depending on the geometry of the parts. When the column is submitted to axial loading, the model without diaphragm the value of the ultimate bending moment resistance presents a gradual reduction between 3.2% (for the smallest diaphragm) and 17%.
- ItemAnálise dinâmica de estruturas de aço suportes de máquinas rotativas(Universidade Federal do Espírito Santo, 2014-11-07) Ferro, Rafael Marin; Ferreira, Walnório Graça; Calezani, Adenilcia Fernanda Grobério; Oliveira, Romilde Almeida deAdequate dynamic analysis is needed to check for Support Frame Structures of mechanical equipment to ensure not only the human user comfort as well as good conditions for the operation of equipment structure. Recent studies of Structural Dynamics and Dynamics of equipment see the difficulty in performing real models of Support Frame Structures of Rotating Machinery. Booth areas have in common study Analysis of Vibrations produced by Dynamic Loads is necessary a study comparing the two areas, which are considered the dynamic loads caused by rotating machinery in checking Support Frame Structures.. This thesis is based on a survey of the real operating conditions of Rotating Machines such as pumps, compressors and fans, targeting the correct application of Dynamic Loads produced by the equipment applied in Support Frame Structures. With the data of speed, acceleration, frequency and consequently vibration, the set will be generated Computational models of Support Frame Structures. Models of Structures with loads of equipment applied, carried out with the aid of software strap. Will be generated, in Dynamic Module, models of Support Frame Structures with connections rigid, pinned or semi-rigid. Varying loads of a model of Rotating Machinery, this study will use a centrifugal pump we can see which have the best Support Frame and Performance with enhanced reliability in relation structure versus vibration. For the purpose of design models, we use Support Frame Structures of rotating machines used in real Industries models.
- ItemAnálise dinâmica de pisos mistos em aço-concreto submetidos a atividades humanas rítmicas(Universidade Federal do Espírito Santo, 2007-05-23) Loose, Juliane Klug; Silva, José Guilherme Santos da; Ferreira, Walnório Graça; Sá, Pedro Augusto Cezar Oliveira de; Faísca, Renata GonçalvesThe application of dynamic analysis in structures is growing together with the new technologies of construction. Knowledge about the behavior of materials and its consequent optimized usage allow making structures more and more slender. This tendency of design are leading to structures systems with natural frequencies much and much lower and, therefore closer to the frequency of the dynamic excitation associated to the human beings activities, such as: walking, running and jumping. As a consequence, dynamic loads due to human rhythmic activities can be enough to cause frequencies near the resonance, making the system sufficiently vulnerable to the effects of vibrations, exceeding the recommended limits for human comfort, resulting in discomfort for people. This work intends to study the behavior of composite floor systems (steel-concrete), subjected to human rhythmic activities like aerobic activities and free jumps. For such, analysis in composite floor models will be done using the Finite Element Method (FEM). It was considered the usual techniques of discretization using the computer program Ansys. The beams are simulated by finite elements considering flexion and torsion effects. The concrete floors are simulated by elements with membrane capability. The dynamics loads were modeling using diferents metodologies. One of these, uses experimental parameters that considere effects produced by crowds, and other, use parameters from international recomendations. Later, the results obtained, in terms of the maximums accelerations (peaks accelerations), are confronted and compared to those supplied by the technical literature available about the subject, from the point of view of human comfort. The results obtained in this study show that composite floors analyzed are submitted to high accelerations that can be cause problems, because exceed the limits associated to the human comfort.
- ItemAnálise e dimensionamento de vigas mistas de aço e concreto com protensão externa(Universidade Federal do Espírito Santo, 2018-06-29) Ribeiro, Karla Demoner; Luchi, Lorenzo Augusto Ruschi e; Calenzani, Adenilcia Fernanda Grobério; Azevedo, Macksuel Soares de; Silva, Ana Lydia Reis de Castro eSteel and concrete composite beam is an efficient structural system to support gravitational loads of floors and buildings because it is ease to construction and it reduces the weight of the steel beam. Searching for new materials and constructive technologies, it was observed that the external prestressed is one of the techniques adopted to improve the structural behavior of a material. In Brazil, prestressed steel and concrete structures is still not widely used, because there is very little disclosure about it and there‟s a lack of clear norms and formulations about it. There are analytical studies on prestressed composite beams, but there is a lack of works in the literature about design methodologies. This work aims to discuss methodologies which deals with the analysis and the designing of steel and concrete composite beams simply supported with "I" steel sections double symmetrical and monosymmetric using the pre tensioning technique. A computational program was developed to perform the analysis and the desing of these beams, based on the calculation methodology of ABNT NBR 8800: 2008 and in the stresses analysis, which is tested comparing with a manually solved example. Using the computer program, a parametric study was carried out to analyze the influence of the length of the span, the degree of monosymmetry of the cross section of the steel profile and the eccentricity of the prestressing force in the resistant capacity of the beams. The results of the research indicate that although the prestressing has generated a considerable improvement in the behavior of the composite beams to the flexion, reducing the acting bending moment and increasing the resistant bending moment, there was little advantage in relation the to the optimization of the steel profile because the force of pretension introduces compression stresses. The effects of the prestressing were much more beneficial for the beams of double symmetrical profile than for the ones of monosymmetrical profile. In this research it was not possible to conclude which eccentricity provides the greatest flexural resistance since there was no considerable variation in resistance when there is variation in this parameter.
- ItemAnálise numérica de pilares de aço com restrições axial e rotacional em situação de incêndio(Universidade Federal do Espírito Santo, 2016-09-05) Bubach, Caroline Rainha; Silva, Valdir Pignatta e; Azevedo, Macksuel Soares de; Ferreira, Walnório Graça; Munaiar Neto, JorgeThe performance of a steel column in fire is highly influenced by its interaction with the beams, slabs and columns of the surrounding structure, because the different thermal strains developed between the heating elements and the elements that remain relatively cold develop axial and rotational restraints in the column that modify its critical temperature and fire resistance. Studies of the influence of axial and rotational restraints on the fire resistance of steel columns are recent and most of the research carried out only considered the influence of axial restraint, without taking into account the rotational restraint. This study aims to analyze the behavior of I section steel columns in fire with axial and rotational restraint, in isolation and acting simultaneously. The influence of the slenderness of the column, the load level and axial and rotational restraint ratio were analyzed numerically using the finite element program ANSYS v17.0. The main results were that the two restraints, the axial and rotational, have opposite effects on the fire resistance of the columns and the larger the load level and slenderness, lower fire resistance. The critical times and critical temperature values numerically obtained were compared with the formulation of the ABNT NBR 14323: 2013.
- ItemDimensionamento otimizado de vigas alveolares de aço(Universidade Federal do Espírito Santo, 2017-02-22) Lubke, Gabriela Pereira; Azevedo, Macksuel Soares de; Alves, Élcio Cassimiro; Camargo, Rodrigo Silveira; Parente Junior, EvandroOpen web-expanded steel beams are structural elements achieved by cutting the web of the root beam in a certain pattern and then welding two parts each other. As a result of these processes the overall beam depth increases which in return causes increase in the capacity of the original section. The openings, together with the addition of useful profile height, make this type of beam susceptible to new ways of collapse, and increases existing failure modes. This paper proposes a formulation for the design of cellular beams steel optimally using the formulations developed by Cimadevilla (2000), Abreu (2011), Silveira (2011) and Veríssimo et al. (2012), takinginto account the geometry of restrictions set by Oliveira (2012). The validation of the computer program developed for the accomplishment of results with results obtained through manually solved examples as the basis of a descriptive formulation by Veríssimo et al. (2012), as the Brazilian standard does not define the design parameters for this type of profile. The program was developed in the Matlab platform, and for a solution of the optimization problems were used in internal Matlab algorithms, such as interior points, quadratic programming and genetic algorithms. Initial examples point out that the sizing can be improved and no case of profiling a new cut line can be defined.
- ItemEstudo da área líquida efetiva de chapas e cantoneiras de aço tracionadas e ligadas por parafusos(Universidade Federal do Espírito Santo, 2005-06-07) Veronez, Jane Suave; Sá, Pedro Augusto Cezar Oliveira de; Ferreira, Walnório Graça,; Coelho, Luiz Herkenhoff; Ribeiro, Luiz Fernando LoureiroThis work presents a study of the net section rupture of bolted flat plates and single angles of steel tension members capacities. The modes of failure of the tension members subjected to static loads and connected with bolts are exposed at first. After that, the mode of failure of rupture of net section is established as the center of interest. A brief report above researches about the subject is presented and the sources of design calculations used by some current specifications are indicated. Afterwards, design calculations for service ability criterion, used by current specifications for laminated, welded and cold formed steel members, are presented and the divergences between those criterions are pointed out. A comparative analysis with numeric examples with laminated and welded members is accomplished, in order to exemplify the specification prescriptions. A numeric simulation of plates with concentric connections and single angles with eccentric connections are realized by the finite element analysis (FEA), in the program Ansys 5.5. After the presentation of the results, procedures to calculate the resistance of the studied models are proposed, and a comparative analysis between the results obtained on the numeric simulation and on the design calculations for service ability criterion is realized, showing the differences between them and indicating the ones that have more approximation with numeric results.
- ItemOtimização de estruturas treliçadas geometricamente não lineares submetidas a carregamento dinâmico(Universidade Federal do Espírito Santo, 2019-03-29) Martinelli, Larissa Bastos; Alves, Élcio Cassimiro; Ferreira, Walnório Graça; Parente Junior, Evandro; Silveira, Ricardo Azoubel da MotaThis study addresses the optimization of lattice structures with geometrically nonlinear behavior under dynamic loading. The formulated optimization problem aims to determine the cross-sectional area of the bars which minimizes the total mass of the structure, imposing constraints on nodal displacements and stresses. In order to solve this optimization problem, it was developed a computational program on MATLAB®, using the Interior Point method and the Sequential Quadratic Programming method, the algorithms of which are available on Optimization Toolbox™. It was included routines for grouping the bars and to convert the optimal solution obtained using continuous design variables in commercial values of structural hollow-sections. The space truss nonlinear finite element is described by an updated Lagrangian formulation. The implemented geometric nonlinear dynamic analysis procedure combines Newmark’s method with Newton-Raphson type iterations, being validated by comparison with solutions available in the literature and with solutions obtained using ANSYS® software. Examples of plane and space trusses under different dynamic loading are solved using the developed computational program. The results show that: the Sequential Quadratic Programming method is the most efficient to solve the studied optimization problem, consideration of structural damping can lead to a significant reduction in the total mass, the use of the conversion procedure for commercial sections provides solutions in favor of security and the grouping of bars generates a satisfactory duration for the optimization process.