This diploma thesis deals with the design and assessment of the steel structure of the administrative building. The building is situated in Svitavy. The construction has several floors, the ground plan is L-shaped. Other floors have a rectangular ground plan. The external ground plan dimensions of the building are 55.2 m × 72 m. The building has terraces and three height levels occupied. At the first height level the building reaches 5 floors, the other 7 floors and the top 9 floors. the main material will be S235 steel on the construction.

Master thesis describes the design and assessment of main parts monolithic reinforced concrete construction of office building. Solved elements are locally supported slab, stiffening perimeter beam, column, wall and fundamention strip. Components of master thesis are also drawings of shape and reinforcement. Calculation of internal forces was performed by computer program SCIA Engineer. It was control by simplified method of replacement frames and results were compared.

Cette thèse s’inscrit dans une démarche d’amélioration des connaissances des instabilités des éléments comprimés et fléchis sensibles aux effets du second ordre. Il s’agit de traiter la prise en compte des imperfections initiales dans l’analyse de la structure et d’adapter les critères actuels de vérification pour les structures tubulaires de type échafaudage. Les formulations existantes, proposées dans la littérature et les codes de calculs, sont souvent issues d’hypothèses, et conduisent à des incohérences entre les critères de vérification en section, et les critères de vérification en instabilité. L’approche développée traite l’interaction entre la résistance en section et les phénomènes d’instabilités, et inclut l’influence des imperfections initiales. Ces effets seront, dans la mesure du possible, découplés. À ce titre, une méthode a été conçue pour permettre la définition des imperfections initiales d’une structure, de manière à être la plus précise possible. Cette méthode, basée sur la définition d’une imperfection unique, d’allure identique à la déformée critique du mode de flambement prépondérant, est une méthode précise, entièrement définie permettant de tenir compte des caractéristiques géométriques, des caractéristiques mécaniques intrinsèques, des conditions aux limites et de la forme du chargement, dans la définition de l’imperfection initiale unique d’une structure. Une campagne d’essai a été réalisée en collaboration avec le SFECE, visant à analyser le comportement expérimental au flambement de sections tubulaires formées à froid. Des essais de flambement sur des échelles d’échafaudage, provenant de divers fournisseurs européens, ont été effectués. Une étude statistique des résultats expérimentaux a permis de mettre en évidence que le facteur d’imperfection actuellement défini pour les sections tubulaires formées à froid est bien trop pénalisant à l’égard des sections usitées dans le domaine des échafaudages. Afin de répondre à la problématique, de nouveaux critères de vérification en instabilité ont également été établis en utilisant une approche similaire à celle d’Ayrton-Perry. Ces nouveaux critères permettent de s’affranchir de la modélisation des imperfections initiales tout en offrant une estimation sûre et précise du facteur de sollicitation d’une structure. Des études comparatives ont été menées de manière à s’assurer de la sécurité des formulations proposées par rapport aux critères de vérification en section de la norme actuelle. / This thesis is part of an effort to improve knowledge of the instabilities of beam-columns sensitive to second-order effects. The works deal with the means to take into account the initial imperfections in the structural analysis and to adapt the current verification criteria for tubular section structures, such as scaffold structures. The existing formulations, proposed in the literature and calculation codes, are often based on hypotheses, and thus lead to inconsistencies between, on the one hand, the verification criteria in section, and on the other hand, the verification criteria in instability. The developed approach takes into account the interaction between section resistance and instability phenomena, and includes the influence of initial imperfections (initial defect of aplomb, lack of straightness, residual stresses). As far as possible, these effects will be decoupled. As such, a method has been developed to allow the definition of initial imperfections of a structure, to be as accurate as possible. This method, based on the definition of a single imperfection, identical in appearance to the shape of the predominant critical buckling mode, is a precise, fully defined method to take into account the geometric characteristics, intrinsic mechanical characteristics, limits and the form of loading, in the definition of the initial imperfections of a structure. A test campaign was carried out in collaboration with the French Syndicate of Scaffolding, Formwork and Shoring (SFECE), aiming to analyze the experimental behavior of buckling of cold-formed tubular sections. Nine buckling tests on scaffold ladders, from various European suppliers, have been carried out. A statistical study of the experimental results has made it possible to highlight that the imperfection factor currently defined for the cold-formed tubular sections is far too penalizing for the sections used in the field of scaffolds. In order to respond to the problem, new instability criteria have also been established using a similar approach to that of Ayrton-Perry. These new criteria make it possible to free ourselves from the modeling of initial imperfections while offering a safe and accurate estimate of the stress factor of a structure. A comparative study was conducted in order to ensure the safety of the proposed formulations as regards the section verification criteria of the NF EN 1993-1-1 current standard.

The concept of semi-rigid composite connection has been widely researched in the past; however, most of the researches are limited to composite joints with metal deck ¿ooring and solid concrete slabs. Composite construction incorporating precast concrete hollowcore slabs (HCU) is a recently developed composite ¿oor system for buildings. The research on the structural behaviour of the semi-rigid composite joints with HCU is new and without any previous experimental database. In this paper, eight full-scale tests of beam-to-column semi-rigid composite joints with steel beams and precast hollowcore slabs are reported. The variables are stud spacing, degree of the shear connections, area of the longitudinal reinforcement and slab thickness. The test set-up and instrumentation is described in detail. The experimental behaviour is analysed and based on the test data the structural behaviour of these semi-rigid composite joints is discussed. Based on the experimental data, a simpli¿ed method to predict rotation and moment capacity for this type of composite connection is proposed.

Este trabalho aborda o estudo de pilares preenchidos flexo-comprimidos e algumas ligações viga-pilar preenchido. Para ambos, são realizadas experimentações com modelos físicos e numéricos, sendo que para os pilares preenchidos um amplo estudo paramétrico foi desenvolvido. Ao todo, foram ensaiados 13 pilares preenchidos flexo-comprimidos, cujos valores de força última são comparados com aqueles provenientes da simulação numérica via programa CFT e, os demais resultados, comentados e discutidos. Aferido, o programa CFT foi utilizado no estudo paramétrico com o intuito de avaliar a influência de parâmetros como resistência dos materiais, excentricidade da força axial, eixo de flexão e relação lado/espessura na capacidade resistente do pilar preenchido. Quanto às ligações viga-pilar, foram ensaiadas 4 tipologias de ligação, sendo duas compostas por chapas de extremidade e parafusos passantes e duas soldadas, sendo uma delas enrijecida por cantoneiras soldadas no interior do perfil tubular. Discutem-se os resultados, sobretudo quanto ao comportamento momento-rotação das tipologias investigadas. As ligações também foram investigadas via simulação numérica e os resultados obtidos permitiram elaborar diretrizes para o aprimoramento de tais simulações. Por fim, são apresentadas as conclusões pertinentes a este trabalho e recomendações para novas pesquisas / This research thesis presents a study of concrete filled steel columns subjected to combined bending and compression and beam-column connections. In both cases, tests were conducted on physical and numerical models, resulting in the development of a wide range of parametric studies for the case of the concrete filled steel columns. 13 concrete filled steel columns were tested under combined bending and compression loads whose ultimate values were compared to ultimate forces obtained from numerical simulations using the CFT computer program. After calibration, the computer program was used in the parametric study with the aim of verifying the influence of parameters, such as the material strength, eccentricity of the axial force, bending axis and breadth/thickness relation, on the ultimate load carrying capacity of the concrete filled steel columns. With respect to the beam-column connections, four types of connections were tested, two of them composed of endplate and bolts, while the other two were welded, with one of them stiffened by an angle steel placed inside the steel tube. The obtained results are discussed, giving more emphasis to the bending moment-rotation behaviour of the tested specimens. The beam-column connections were also investigated numerically. The obtained results permit the laying out of important directives for the improvement of such numerical simulation tools as the one employed in the present thesis. Lastly, pertinent conclusions relative to this thesis and recommendations for future research are presented

We will create a class of generalized ellipses and explore their ability to define a distance on a space and generate continuous, periodic functions. Connections between these continuous, periodic functions and the generalizations of trigonometric functions known in the literature shall be established along with connections between these generalized ellipses and some spectrahedral projections onto the plane, more specifically the well-known multifocal ellipses. The superellipse, or Lam\'{e} curve, will be a special case of the generalized ellipse. Applications of these generalized ellipses shall be explored with regards to some one-dimensional systems of classical mechanics. We will adopt the Ramberg-Osgood relation for stress and strain ubiquitous in engineering mechanics and define a general internal bending moment for which this expression, and several others, are special cases. We will then apply this general bending moment to some one-dimensional Euler beam-columns along with the continuous, periodic functions we developed with regard to the generalized ellipse. This will allow us to construct new solutions for critical buckling loads of Euler columns and deflections of beam-columns under very general engineering material requirements without some of the usual assumptions associated with the Ramberg-Osgood relation.

This research investigated the behavior of nonseismically detailed reinforced concrete exterior beam-column joints subjected to bidirectional lateral cyclic loading using nonlinear finite element analysis (NLFEA). Beam-column joints constitute a critical component in the load path of reinforced concrete buildings due to their fundamental role in integrating the overall structural system. Earthquake reconnaissance reports reveal that failure of joints has contributed to partial or complete collapse of reinforced concrete buildings designed without consideration for large lateral loads, resulting in significant economic impact and loss of life. Such infrastructure exists throughout seismically active regions worldwide, and the large-scale risk associated with such deficiencies is not fully known. Computational strategies provide a useful complement to the existing experimental literature on joint behavior and are needed to more fully characterize the failure processes in seismically deficient beam-column joints subjected to realistic failure conditions. Prior to this study, vulnerable reinforced concrete corner beam-column joints including the slab had not been analyzed using nonlinear finite element analysis and compared with experimental results. The first part of this research focused on identification and validation of a constitutive modeling strategy capable of simulating the behaviors known to dominate failure of beam-column joints under cyclic lateral load using NLFEA. This prototype model was formulated by combining a rotating smeared crack concrete constitutive model with a reinforcing bar plasticity model and nonlinear bond-slip formulation. This model was systematically validated against experimental data, and parametric studies were conducted to determine the sensitivity of the response to various material properties. The prototype model was then used to simulate the cyclic response of four seismically deficient beam-column joints which had been previously evaluated experimentally. The simulated joints included: a one-way exterior joint, a two-way beam-column exterior corner joint, and a series of two-way beam-column-slab exterior corner joints with varying degrees of seismic vulnerability. The two-way corner joint specimens were evaluated under simultaneous cyclic bidirectional lateral and cyclic column axial loading. For each specimen, the ability of the prototype model to capture the strength, stiffness degradation, energy dissipation, joint shear strength, and progressive failure mechanisms (e.g. cracking) was demonstrated.

A crescente utilização do aço inoxidável como elemento estrutural despertou o interesse de clientes, arquitetos e engenheiros nos últimos anos. Apesar do custo ainda elevado, a sua aplicação na construção civil vem substituindo outros elementos estruturais. Seja por sua alta resistência à corrosão, aumentando a relação custo benefício; sua estética, proporcionando formas cada vez mais ousadas ou; seu apelo ambiental, gerando menos resíduos no meio ambiente. As subestações representam um papel importante no fornecimento de energia. Como possuem grande complexidade para manutenção, foi escolhida a estrutura suporte de seu barramento, para o dimensionamento em aço inoxidável. Desta forma, minimizando as paradas para realização de manutenções das estruturas, possibilitando maior qualidade no fornecimento de energia elétrica. Para fins comparativos foi escolhido o projeto de uma SE existente, cuja estrutura de suporte do barramento, foi construída por treliças formadas por cantoneiras de aço carbono galvanizado. Inicialmente, o dimensionamento foi desenvolvido utilizando perfis H e I funcionando como viga-coluna para os dois tipos de aço. Num segundo momento, a estrutura foi dimensionada como treliças planas. Todos os dimensionamentos foram realizados de acordo com as prescrições normativas do EUROCODE 3. Após realização dos dimensionamentos, foram apresentadas as análises comparativas dos custos envolvidos para os tipos de aço. Abordando o investimento inicial, os gastos com manutenção ao longo da vida e os custos elétricos agregados à redução das paradas para manutenção. / The increasing use of stainless steel as a structural element motivated, in recent years, the continuous interest of customers, architects and engineers. Despite its high cost, its application in construction have been replacing other structural elements. This is mainly due to its high corrosion resistance that increases its cost-effective ratio, its aesthetic that enables the construction of increasingly bold forms and its environmental appeal that generates less environmental waste. The electric power substations represent an important role in the global energy supply. Since its maintenance is a complex and costly process, one of its bus support structure was chosen to be designed in stainless steel. This strategy minimizes the number of stoppages for structural maintenance, enabling a higher quality power supply. For comparative purposes an existing power substation has been chosen where the bus supporting structure was made of galvanized carbon steel angle bar trusses. Initially, the design adopted I and H profiles functioning as beam-column for the two types of steel analyzed. In a second stage, the structure was designed as a plane truss. All designs were performed in accordance to the requirements of EUROCODE 3 standard. This was followed by comparative analyses of the costs involved for the studied steel types. These analyses involved the initial investment assessment properly contextualized with the posterior spending on maintenance and electrical costs of the stoppages and were set against the gains in reducing the downtime for maintenance of the stainless steel solution.

Made available in DSpace on 2016-06-02T20:09:05Z (GMT). No. of bitstreams: 1 DissBC.pdf: 11069989 bytes, checksum: b3c92f78ccad794ee5c2bb5f907f4814 (MD5) Previous issue date: 2007-02-28 / Universidade Federal de Minas Gerais / The behaviour of prestressed precast beams is directly affected by the rotational stiffness of the end connections. Although the prestressed beam presents a linear behaviour in service, the effective behaviour of the precast beam depends on the interaction of the beam with the behaviour of its connections. The majority of the experimental investigations on semi-rigid connections in precast concrete structures are focused on the testing of isolated models of connections aiming to the characterization of their moment-rotation relationships. However, the effective behaviour of precast beams with semi-rigid connections can only be determined through tests of precast subframes, wherein the interaction of the beam with its connections can be evaluated. The present research presents a development of an experimental procedure for testing of precast subframes with semi-rigid connections, which integrates analytical equations, allowing estimate the partial restrained moment at the beam-column connections. Using this approach, this research presents the results of an experimental investigation. With the experimental inquiry of the prestressed beam behavior together with the beam-column connections of extremity, through physical tests, was possible esteem the partial restrained in the beam-column connections, despite in exploratory character. Were testing two models, being one compose for a prestressed beam with semi-rigid connections, and the other compose for a simply supported prestressed beam With the analyses of the experimental results for the studied models, the effective restrained of the connections, in other words, the capacity of restriction to the rotation of beam-column connections of extremity in the U.L.S, was esteem as being a value between 60% and 70%, presenting, thus, a good performance. Although these results are restricted to the negative moments, it gives credit that these connections possess one high potential for application in porches, because the detail used in the interface between the beam and the column made possible a bigger capacity of restriction to the rotation of the connection / O comportamento das vigas pré-moldadas de concreto protendido é diretamente afetado pela relação momento-rotação do apoio. Dessa forma, embora a viga protendida apresente um comportamento linear, o comportamento conjunto viga e ligações, é determinado pela não linearidade das ligações. Os estudos experimentais existentes sobre o comportamento das ligações semi-rígidas em estruturas pré-moldadas têm se restringido a caracterização da rigidez à flexão de maneira isolada, devido principalmente à falta de uma metodologia experimental que integre parâmetros teóricos de controle, como o fator de restrição à rotação αR e o procedimento Beam-line. Na presente pesquisa, desenvolveu-se um procedimento experimental, através do qual foi possível integrar diversos equacionamentos teóricos, que levam em consideração diferentes parâmetros para a análise dos resultados. Com a investigação experimental do comportamento conjunto de uma viga pré-moldada de concreto protendido e de suas ligações viga-pilar de extremidade, a partir de ensaios físicos de dois modelos, foi possível estimar o engastamento parcial nas ligações viga-pilar. Foram ensaiados dois modelos, sendo um composto por uma viga protendida com ligações semirígidas, e o outro composto por uma viga protendida bi-apoiada, ainda que em caráter exploratório Com base nas análises dos resultados experimentais obtidos para os modelos estudados, o engastamento parcial efetivo da ligação, ou seja, a capacidade de restrição à rotação da ligação viga-pilar de extremidade, no Estado Limite Último, foi estimada como sendo um valor entre 60% e 70%, apresentando, assim, um bom desempenho. Embora tais resultados sejam restritos aos momentos negativos, acredita-se que essa ligação possui um elevado potencial para aplicação em pórticos, na medida em que o detalhe utilizado na interface entre a viga e o pilar possibilitou uma maior capacidade de restrição ao giro da ligação

Made available in DSpace on 2016-06-02T20:09:20Z (GMT). No. of bitstreams: 1 5921.pdf: 11584429 bytes, checksum: 4d7bb957789e3b6f82534465e38a31d4 (MD5) Previous issue date: 2014-04-14 / Among all of the existing structural systems, the steel-concrete composite elements outstands because it takes advantage of the properties of both materials in the same element. Unlike the system in reinforced concrete cast in situ, the steel-concrete composite system is not monolithic, and therefore the global behavior of the structure is mainly linked to the behavior of the connections. Currently, the beam-column connections have been the subject of theoretical and experimental studies to better understand their structural behavior. This concern has become even bigger with the introduction of requirements on steel-concrete composite connections in the Brazilian standard ABNT NBR 8800:2008. In order to contribute to this subject, in this work is studied by numerical modeling, a detail of a composite beam-column connection with shear plate using numerical models. The numerical analysis performed in the computer package ANSYS® was divided in two phases: validation of the numerical model from experimental results and subsequent parametric analysis. Despite of the simplifications adopted in the numerical simulation, the results were satisfactory and representative of the experimental behavior, especially for Force vs. Displacement at the end of the beam. Once validated the numerical model, a parametric study was conducted in order to evaluate the influence of some parameters on the bearing capacity of connections, such as the concrete slab reinforcement ratio, the slab thickness and the steel beam depth. The results of the parametric analysis showed that the variation of the slab thickness was the parameter with more influence on the bearing capacity of the composite connection with shear plate. / Dentre os sistemas estruturais existentes destaca-se aquele formado por elementos mistos de aço e concreto. Este sistema utiliza as vantagens dos materiais estruturais mais utilizados na construção civil, o aço e o concreto, agrupando-os em um único elemento estrutural. Diferentemente do sistema em concreto armado moldado in loco, o sistema misto de aço e concreto não é monolítico e, portanto, o comportamento global da estrutura está principalmente atrelado ao comportamento das ligações. Atualmente as ligações viga-pilar têm sido alvo de estudos teórico-experimentais visando melhor compreender seu comportamento estrutural. No Brasil esta preocupação tornou-se ainda maior com a introdução de prescrições sobre ligações mistas de aço e concreto na norma brasileira ABNT NBR 8800:2008. Visando contribuir neste sentido, no presente trabalho é estudado, via modelagem numérica, um detalhe de ligação mista viga-pilar com chapa passante. A análise numérica realizada no pacote computacional ANSYS® foi dividida em duas etapas: validação do modelo numérico a partir de resultados experimentais com posterior análises paramétricas. Apesar das simplificações adotadas na simulação numérica, os resultados foram considerados satisfatórios e representativos do comportamento experimental, sobretudo da curva Força vs. Deslocamento na extremidade da viga. Uma vez validado o modelo numérico, o estudo paramétrico foi realizado com vistas a avaliar a influência de alguns parâmetros na capacidade resistente da ligação. Os parâmetros avaliados foram: taxa de armadura da laje de concreto, altura da laje e altura do perfil de aço da viga mista. Os resultados da análise paramétrica mostraram que a variação da altura da laje foi o parâmetro que mais influenciou na capacidade resistente da ligação mista com chapa passante.