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1
Mashiri, Fidelis Rutendo 1968. "Thin-walled tubular connections under fatigue loading." Monash University, Dept. of Civil Engineering, 2001. http://arrow.monash.edu.au/hdl/1959.1/8784.
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2
Branco, Renato Henrique Ferreira. "Automação de projetos de estruturas planas treliçadas tubulares de aço com estudo comparativo entre treliças constituidas por barras com ligações rotuladas e rigidas." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257810.
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Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho tem como objetivo apresentar análises comparativas entre estruturas metálicas treliçadas tubulares planas considerando as vinculações entre as barras como rotuladas e estruturas metálicas treliçadas tubulares planas considerando as vinculações entre as barras como rígidas. A motivação deste estudo foi determinar qual a importância da rigidez das barras no dimensionamento das mesmas estruturas quando são consideradas diferentes vinculações entre as barras. Foram encontradas diferenças nos dimensionamentos quando as barras são ¿curtas¿ e conseqüentemente, bastante rígidas. Nestes casos, onde as barras são rígidas, a consideração de rótula leva a resultados que não condizem com o comportamento real da estrutura e, conseqüentemente, a um dimensionamento inadequado da estrutura tubular. Para agilizar as análises, foi desenvolvido um software que automatiza as etapas principais de um projeto de estruturas metálicas tubulares planas, com o objetivo de enquadrar tais análises em condições que respeitem os parâmetros normativos de ângulos entre barras, limites de esbeltez, entre outros. As etapas automatizadas foram: geração automática de determinadas geometrias, cálculo dos coeficientes de pressão e forma do vento e pressão dinâmica, carregamento automático da estrutura, cálculo estrutural e dimensionamento da estrutura. O programa possui uma interface amigável, integrada e ágil que permite aos projetistas de estruturas metálicas realizarem diversas análises possibilitando de forma rápida a escolha da solução mais adequada para a estrutura
Abstract: This research has the objective to present a comparative analysis between steel plane tubular trusses that consider the member¿s end connections as released and steel tubular plane trusses that consider the member¿s end connections as non-released (rigid). This study intends to measure the member¿s stiffness importance for the design of these members when them are considered released or not. It was found differences when the members were ¿short¿ and very rigid. In this cases, when the members were rigid, the released consideration takes to results that don¿t represent the real behavior of the structure and, consequently, to an inadequate design of the tubular structure. To make the analysis faster, it was developed a software that automate the major steps of a steel tubular structure design, with the objective to fit the analysis in the standard design recommendations, like angles between members, stiffness limits, and others. The automated steps were: automatic generation of geometries, automatic wind pressure calculation, automatic structure load insertion, structural analysis and steel structure design based on Brazilian codes. The software has a friendly interface, which allows engineers realize several analyses and, thus, choose the most adequate solution for the structure
Mestrado
Estruturas
Mestre em Engenharia Civil
3
Feng, Ran. "Design of cold-formed stainless steel tubular joints." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290628.
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4
Zhou, Feng. "Web crippling of cold-formed stainless steel tubular sections." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37228316.
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5
Chao, Min, of Western Sydney Hawkesbury University, Faculty of Science and Technology, and School of Construction and Building Sciences. "The design and behaviour of concrete filled steel tubular beam-columns." THESIS_FST_CBS_Chao_M.xml, 2000. http://handle.uws.edu.au:8081/1959.7/92.
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Concrete filled steel tubular (CFST) columns are widely used in building and infrastructure projects throughout the world.Compared with other form of construction CFST columns offer superior structural performance and speed and ease of construction.Design procedures and recommendations provided in most of the design codes are often tedious and complex. There have been attempts to simplify the design procedure by providing a simplified expression to predict the capacity of a CFST under a general loading condition.In this thesis a rigorous analysis procedure was presented for the analysis of CFST beam-columns under general loading conditions.All the analytical results were verified by comparisons with the available test results and current ACI, AISC AND Eurocode 4 design codes. The comparisons demonstrated that the proposed numerical equations are accurate, and slightly conservative. Based on the numerical analysis, a simple and easy to follow calculation procedure was proposed for design of CFST columns under either uniaxial or biaxial bending moment and axial load.Doctor of Philosophy (PhD)
6
Khamisi, Ali. "Stability of Tubular Steel Structures : Buckling and Lateral Torsional Buckling." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0172.
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Ce sujet est d’actualité suite à une évolution rapide des types de conception de structures élancées utilisées dans les installations provisoires. C’est seulement depuis une vingtaine d’années que ces structures sont préfabriquées en cadres multidirectionnels (de sections tubulaires en acier ou en aluminium). Ces structures sont légères et leur stabilité réside seulement dans les raideurs internes au niveau des files de montants et au niveau horizontal par les planchers ainsi que dans les liaisons avec l’ouvrage. Ce travail concerne l’étude des instabilités (flambement-déversement) en tenant compte de différents types d’imperfections. De nouvelles courbes de flambement ainsi que les facteurs d’imperfection associés sont proposés dans cette thèse. Ces courbes sont obtenues en imposant une déformée initiale représentant les défauts géométriques et mécaniques (contraintes résiduelles). Les résultats expérimentaux confrontés avec les prévisions théoriques de l’Eurocode 3 montrent que les valeurs des imperfections figurant dans la littérature sont extrêmement exagérées. Les valeurs préconisées dans ce travail pourraient présenter un certain intérêt pour une modification éventuelle des courbes européennes de flambement pour ce type de structure. En ce qui concerne l’instabilité latérale, une méthodologie originale d’essais en vraie grandeur de poutres à treillis formés d’éléments tubulaires a été également mise au point. Le système de chargement à « roues libres » développé permet de libérer le point d’application de l’effort dès le début de l’instabilité. Cette technique conduit à des mesures plus précises du moment critique de déversementThis subject becomes topical following a rapid evolution of design procedures for slender structures used widely in the temporary installations. Only through the last twenty years that these structures are prefabricated of multidirectional frames (steel or aluminium tubular sections). These structures are lightweight and their stability lies only in the internal stiffness at rows of posts and horizontally by the planking as well as the links with the building. This work concerns the study of instabilities (buckling - lateral torsional buckling) taking into account different types of imperfections. New buckling curves and the associated imperfection factors are proposed in this thesis. These curves are obtained by imposing an initial deformed representing the geometrical and mechanical defects (residual stress). The experimental results were confronted with theoretical predictions of Eurocode 3 which show that the values of the imperfections in the literature are extremely exaggerated. The values advocated in this work could be of interest for a possible adjustment of the European buckling curves for this type of structure. Regarding the lateral instability, an original methodology in real scale tests of trusses consist of tubular elements was also developed. The developed loading system of "free wheels" allows releasing the point of application of the force from the beginning of instability. This technique leads to more accurate measurements of the critical lateral torsional buckling moment
7
Nezamian, Abolghasem 1968. "Bond strength of concrete plugs embedded in tubular steel piles." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5601.
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8
Feng, Ran, and 馮然. "Design of cold-formed stainless steel tubular joints." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41290628.
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9
Hou, Chien-ann. "Modeling and control of welding distortion in tubular frame structures /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487265143145759.
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10
Lui, Wing Man. "Design of cold-formed high strength stainless steel tubular columns and beam-columns /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20LUI.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 149-154). Also available in electronic version. Access restricted to campus users.
11
Zhou, Feng, and 周鋒. "Web crippling of cold-formed stainless steel tubular sections." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37228316.
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12
Chao, Min. "The design and behaviour of concrete filled steel tubular beam-columns." Thesis, View thesis View thesis, 2000. http://handle.uws.edu.au:8081/1959.7/92.
Full textAbstract:
Concrete filled steel tubular (CFST) columns are widely used in building and infrastructure projects throughout the world.Compared with other form of construction CFST columns offer superior structural performance and speed and ease of construction.Design procedures and recommendations provided in most of the design codes are often tedious and complex. There have been attempts to simplify the design procedure by providing a simplified expression to predict the capacity of a CFST under a general loading condition.In this thesis a rigorous analysis procedure was presented for the analysis of CFST beam-columns under general loading conditions.All the analytical results were verified by comparisons with the available test results and current ACI, AISC AND Eurocode 4 design codes. The comparisons demonstrated that the proposed numerical equations are accurate, and slightly conservative. Based on the numerical analysis, a simple and easy to follow calculation procedure was proposed for design of CFST columns under either uniaxial or biaxial bending moment and axial load.
13
DOTTORE, ALEXANDRO. "FINITE ELEMENT FATIGUE ASSESSMENT OF STEEL TUBULAR JOINTS IN OFFSHORE STRUCTURES." Doctoral thesis, Università degli studi di Pavia, 2022. http://hdl.handle.net/11571/1460427.
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Background: Fatigue analysis is a very complex process, which is still today not fully under-stood. This thesis numerically investigates the advantages and limitations of the employment of the Finite Element (FE) method in actual standard fatigue design procedure. Two studies are conducted to validate the SCF calculation and the application of Hot-Spot Stress (HSS) method to fatigue design.
Study I: The Stress Concentration Factor is a magnification factor introduced to account for geometrical or material discontinuities in structural joints. In these locations the stress may reach values several times higher than the nominal stress and may lead to the premature collapse of the structure when subjected to fatigue loading. However, current methodologies to compute the SCF cover only a limited number of joint types and configurations. The aim of this study is to investigate the SCFs in tubular joints through the application of empirical formulas and an extensive numerical analysis campaign. SCFs are assessed for several types of tubular joints and loading conditions according to current standards and literature. Obtained results are compared together to highlights the weaknesses and strengths of each approach and to investigate their implications for the design of tubular joints.
Study II: Fatigue is one of the most frequent causes of steel structures failures, particularly in offshore platforms. Thus, the fatigue life assessment is one of the most relevant procedures for the comprehensive evaluation of both the load-carrying capacity and service life of the structure. The standard fatigue procedure consists of the method of local stress, the so-called Hot-Spot Stress (HSS) applied on a global analysis model. HSS method consists in calculating the stress occurring in the cross sections of the whole elements and applying them a multiplying factor to account for the geometry of the detail. At present, the use of Finite Element makes possible looking for more accurate fatigue stress ranges calculation. This study presents fatigue assessment of representative types of tubular joints in welded offshore platform. Joint fatigue damages are calculated performing global and local FE analyses. The obtained results are com-pared together to evaluate the limits and advantages of the different approaches and model types.
14
DOTTORE, ALEXANDRO. "FINITE ELEMENT FATIGUE ASSESSMENT OF STEEL TUBULAR JOINTS IN OFFSHORE STRUCTURES." Doctoral thesis, Università degli studi di Pavia, 2022. http://hdl.handle.net/11571/1460428.
Full textAbstract:
Background: Fatigue analysis is a very complex process, which is still today not fully under-stood. This thesis numerically investigates the advantages and limitations of the employment of the Finite Element (FE) method in actual standard fatigue design procedure. Two studies are conducted to validate the SCF calculation and the application of Hot-Spot Stress (HSS) method to fatigue design.
Study I: The Stress Concentration Factor is a magnification factor introduced to account for geometrical or material discontinuities in structural joints. In these locations the stress may reach values several times higher than the nominal stress and may lead to the premature collapse of the structure when subjected to fatigue loading. However, current methodologies to compute the SCF cover only a limited number of joint types and configurations. The aim of this study is to investigate the SCFs in tubular joints through the application of empirical formulas and an extensive numerical analysis campaign. SCFs are assessed for several types of tubular joints and loading conditions according to current standards and literature. Obtained results are compared together to highlights the weaknesses and strengths of each approach and to investigate their implications for the design of tubular joints.
Study II: Fatigue is one of the most frequent causes of steel structures failures, particularly in offshore platforms. Thus, the fatigue life assessment is one of the most relevant procedures for the comprehensive evaluation of both the load-carrying capacity and service life of the structure. The standard fatigue procedure consists of the method of local stress, the so-called Hot-Spot Stress (HSS) applied on a global analysis model. HSS method consists in calculating the stress occurring in the cross sections of the whole elements and applying them a multiplying factor to account for the geometry of the detail. At present, the use of Finite Element makes possible looking for more accurate fatigue stress ranges calculation. This study presents fatigue assessment of representative types of tubular joints in welded offshore platform. Joint fatigue damages are calculated performing global and local FE analyses. The obtained results are com-pared together to evaluate the limits and advantages of the different approaches and model types.
15
DOTTORE, ALEXANDRO. "FINITE ELEMENT FATIGUE ASSESSMENT OF STEEL TUBULAR JOINTS IN OFFSHORE STRUCTURES." Doctoral thesis, Università degli studi di Pavia, 2022. http://hdl.handle.net/11571/1460432.
Full textAbstract:
Background: Fatigue analysis is a very complex process, which is still today not fully under-stood. This thesis numerically investigates the advantages and limitations of the employment of the Finite Element (FE) method in actual standard fatigue design procedure. Two studies are conducted to validate the SCF calculation and the application of Hot-Spot Stress (HSS) method to fatigue design.
Study I: The Stress Concentration Factor is a magnification factor introduced to account for geometrical or material discontinuities in structural joints. In these locations the stress may reach values several times higher than the nominal stress and may lead to the premature collapse of the structure when subjected to fatigue loading. However, current methodologies to compute the SCF cover only a limited number of joint types and configurations. The aim of this study is to investigate the SCFs in tubular joints through the application of empirical formulas and an extensive numerical analysis campaign. SCFs are assessed for several types of tubular joints and loading conditions according to current standards and literature. Obtained results are compared together to highlights the weaknesses and strengths of each approach and to investigate their implications for the design of tubular joints.
Study II: Fatigue is one of the most frequent causes of steel structures failures, particularly in offshore platforms. Thus, the fatigue life assessment is one of the most relevant procedures for the comprehensive evaluation of both the load-carrying capacity and service life of the structure. The standard fatigue procedure consists of the method of local stress, the so-called Hot-Spot Stress (HSS) applied on a global analysis model. HSS method consists in calculating the stress occurring in the cross sections of the whole elements and applying them a multiplying factor to account for the geometry of the detail. At present, the use of Finite Element makes possible looking for more accurate fatigue stress ranges calculation. This study presents fatigue assessment of representative types of tubular joints in welded offshore platform. Joint fatigue damages are calculated performing global and local FE analyses. The obtained results are com-pared together to evaluate the limits and advantages of the different approaches and model types.
16
Marshall, Peter William. "Design of welded tubular connections basis and use of AWS code provisions /." Amsterdam ; New York : Elsevier, 1992. http://catalog.hathitrust.org/api/volumes/oclc/26653636.html.
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17
Samarra, Fabio Aurelio. "Estudo numerico-experimental de treliças tubulares planas para coberturas padronizadas para grandes vãos." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257807.
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Orientadores: João Alberto Venegas Requena, Newton de Oliveira Pinto JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: O desenvolvimento de sistemas de cobertura pré-fabricados para grandes vãos, que tenham como características menor tempo de projeto, fabricação e montagem, aliado ao custo competitivo e fator estético, é tema de constantes estudos. O objetivo deste trabalho é desenvolver um sistema de cobertura metálica padronizado e modular utilizando perfis tubulares laminados sem costura. Este sistema se destina principalmente para coberturas de supermercados, shoppings, centros de distribuição, grandes lojas e indústrias, que necessitam de grandes áreas livres. Foi feita, inicialmente neste trabalho, uma descrição de todas as etapas envolvidas em um projeto, destacando, em cada uma, as vantagens e desvantagens da aplicação do perfil tubular. Através de estudos sobre os diversos sistemas de cobertura existentes, tanto no Brasil como no exterior, foi desenvolvido um sistema padronizado de cobertura para atender grandes vãos com utilização de perfis tubulares de seção circular. Para se avaliar o comportamento estrutural deste sistema, foi construído, de maneira inédita no Brasil, um protótipo de 900 m², para testar o sistema construtivo idealizado e realizar ensaios com os carregamentos reais neste tipo de estrutura. Foram realizadas análises experimentais e numéricas, que permitiram comparar o modelo real com o modelo computacional. Através dos modelos numéricos gerados, levando em conta a rigidez das ligações, foi possível identificar qual modelo computacional mais se aproxima com o real. Avaliando-se então o comportamento global da estrutura, com base em todos os resultados numéricos e experimentais obtidos, confirmou-se o comportamento previsto no cálculo computacional com o protótipo ensaiado
Abstract: This strucuture is applied mainly for supermarkets, large stores and industries. Initially, all stages involved on design of steel structure were discussed, especially the advantages and disadvantages of tubular structures. Through the study of existing roof systems, a new system using tubular steel sections was developed. To evaluate the structural behavior of this system a 900m2 prototype was built, an unprecedented occurrence in Brazil, to accomplish experimental tests with usual loads on this kind of structure. Experimental and numerical analyses were done, that allowed to compare the prototype with the numerical results. Evaluating the behavior of the entire structure, with all the results obtained on experimental tests and numerical analysis, it was concluded that the prototype is in accordance with the model
Mestrado
Estruturas
Doutor em Engenharia Civil
18
Dong, Chunxiao, and 董春宵. "Uni-axial behaviour of concrete-filled-steel-tubular columns with external confinement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/195975.
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This thesis studies the uni-axial behaviour of circular double-skinned concrete-filled-steel-tubular (CFST) columns with external confinement in form of external steel rings. Particular attention is paid to the experimental behaviour of double-skinned CFST columns and theoretical model for evaluating the loadcarrying capacity of un- and ring-confined double-skinned CFST columns.
Experimental studies on circular double-skinned CFST columns with various spacing of confinement, concrete strength and hollow ratio were conducted and discussed comprehensively. The mechanical properties of double-skinned CFST columns such as elastic stiffness, elastic strength, load-carrying capacity and ductility are presented. From the result, it is found that the elastic stiffness, elastic strength, load-carrying capacity and ductility are enhanced by installing the external steel rings to the outer tube as external confinement. To verify the effectiveness of external steel rings, the Poisson’s ratios of the double-skinned CFST columns are listed and found to be similar to that of concrete so that a perfect bonding is maintained. To emphasis the excellent performance of double-skinned CFST columns with external rings under uni-axial compression, the load-carrying capacity, elastic strength and elastic stiffness are compared to those of single-skinned CFST columns and reinforced concrete columns.
To fill up the gap that no design model is provided in Eurocode 4 (EC4) for confined double-skinned CFST columns, a theoretical model based on the force equilibrium condition is proposed for evaluating the load-carrying capacity of both un- and ring-confined double-skinned CFST columns. The model takes into account the composite action between the steel tubes and core concrete. To verify the proposed model, numerous test results obtained by the author and other researchers are used for comparing the theoretical results.
According to the above theoretical model above, a parametric study is carried out to investigate the effect of various geometry and material properties on the load-carrying capacity of double-skinned CFST columns. The confining pressure is expressed in terms of geometry and material factors. A simplified design formula is proposed to facilitate the preliminary design of double-skinned CFST columns with and without external confinement.published_or_final_version
Civil Engineering
Master
Master of Philosophy
19
Islam, S. M. Zahurul. "Strengthening of aluminium and stainless steel tubular sections with fibre-reinforced polymer." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47752865.
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Strengthening of aluminium and stainless steel structural tubular sections using
adhesive bonded fibre-reinforced polymer (FRP) subjected to web crippling has been
investigated. Aluminium and stainless steel tubular sections may experience web
crippling failure due to local concentrated loads or reactions. The web crippling
strength can be enhanced by strengthening the webs of the sections in localized
regions. The current international specifications of aluminium and stainless steel
structures do not provide web crippling design rules for strengthening of tubular
sections. Therefore, there is a need to develop safe and reliable web crippling design
rules for FRP strengthened aluminium and stainless steel structures.
An extensive test program was performed on FRP strengthening of aluminium and
cold-formed stainless steel tubular sections subjected to web crippling. The test
specimens consisted of 6061-T6 heat-treated aluminium alloy, ferritic stainless steel
type EN 1.4003 and lean duplex type EN 1.4162 square and rectangular hollow
sections. A total of 254 web crippling tests was conducted in this study. The tests
were performed on eighteen different sizes of tubular sections which covered a wide
range of web slenderness (flat portion of web depth-to-thickness) ratio from 6.2 to
62.2.
The web crippling tests were conducted under the four loading conditions according
to the American Specification and Australian/New Zealand Standard for cold-formed
steel structures, namely End-Two-Flange, Interior-Two-Flange, End-One-Flange and
Interior-One-Flange loading conditions. The investigation was mainly focused on the
effects of different adhesive, FRP, surface treatment, widths of FRP plate and web
slenderness of tubular sections for strengthening against web crippling. Six different
adhesives, six different FRPs, two different surface treatments, three different widths
of FRP plate were considered. It was found that the web crippling capacity of
aluminium tubular sections are significantly increased due to FRP strengthening,
especially for those sections with large value of web slenderness. The web crippling
strength can be increased up to nearly 3 times using the appropriate adhesive and
FRP for aluminium tubular sections, whereas the web crippling strength can be
increased up to 51% and 76% for ferritic and lean duplex stainless steel tubular
sections, respectively.
The finite element models for FRP strengthened aluminium and stainless steel
tubular structural members subjected to web crippling were developed and calibrated
against the experimental results. The debonding between FRP plate and aluminium
or stainless steel tubes was carefully modelled using cohesive element. It is shown
that the calibrated model closely predicted the web crippling strengths and failure
modes of the tested specimens. An extensive parametric study included 212 web
crippling specimens was carried out using the verified finite element models to
examine the behaviour of strengthened aluminium and stainless steel tubular sections
subjected to web crippling.
Design equations are proposed to predict the web crippling strengths of FRP
strengthened aluminium and stainless steel tubular sections based on the
experimental and numerical results. The web crippling strengths obtained from the
tests and numerical analysis were compared with the design strengths calculated
using the proposed equations. The reliability of the proposed design rules was
evaluated using reliability analysis.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
20
Vieira, Rodrigo Cuberos 1983. "Estudo comparativo entre terças de aço, convencionais em vigas, em treliças planas e em treliças multiplanares." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257811.
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Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: As coberturas metálicas são muito utilizadas em edificações que necessitam de grandes espaços internos livres e possuem um prazo de execução pequeno, como por exemplo, galpões comerciais, industriais e centros de armazenamento e distribuição. Dentre as suas partes constituintes, as terças são responsáveis por uma parcela considerável do peso total da cobertura. Neste trabalho foi desenvolvido um amplo estudo sobre os diversos tipos de terças metálicas utilizadas em estruturas metálicas de médio e grande porte, com vãos de até 40 metros, abordando as terças em perfil laminado e formado a frio, e as terças treliçadas em perfis abertos e tubulares. Foram realizados estudos aprofundados sobre o dimensionamento de terças em perfil laminado e formado a frio, com o desenvolvimento de um programa de verificação e dimensionamento para esses tipos de terças. Também foram realizados estudos sobre o dimensionamento de terças treliçadas planas, também conhecidas como joists, que já têm a sua utilização bastante difundida, e de terças treliçadas tubulares multiplanares, cuja utilização ainda é pequena se comparada com os demais tipos de terças. Com esses estudos, foram feitas análises comparativas para diversos vãos, com as ações comumente utilizadas em estruturas que possuem coberturas metálicas, possibilitando identificar qual o tipo de terça mais adequado para cada situação estudada. Uma análise dos custos das terças também foi realizada, permitindo verificar a viabilidade da utilização das terças treliçadas tubulares em coberturas metálicas, principalmente das terças treliçadas tubulares multiplanares, cuja aplicação ainda é pequena.
Abstract: Steel roof systems are widely used in buildings that require large free internal spaces and small execution times, such as commercial and industrial warehouses and storage and distribution centers. The purlins have a considerable contribution in the roof system total weight composition. In this work was developed a study on the different types of purlins for medium and large spans, up to 40 meters, analyzing the hot-rolled sections, cold-formed sections and trusses with open or hollow sections. Purlin design studies were conducted for hot-rolled and cold-formed sections, with a computational software development for these purlin types. The use of planar trusses as purlins, also called steel joists, is already well known, and its design was studied too, as well as the multi-planar tubular trusses, whose use is still small when compared with the other purlin types. With these studies, a comparative analysis was made for various spans, applying the loads commonly used in steel roof systems, allowing the investigation of the best purlin type for each proposed situation. An analysis of the purlin costs was also performed, allowing to study the feasibility of the tubular trusses use in steel roof systems, especially the multi-planar tubular trusses, whose application is still small.
Mestrado
Estruturas
Mestre em Engenharia Civil
21
Ali, Muhammad. "Experimental and Numerical Study of Ductile Metal Auxetic Tubular Structures." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99143.
Full textAbstract:
Methods to mitigate the risk posed by seismic and blast loads to structures are of high interest to researchers. Auxetic structures are a new class of metamaterials that exhibit counterintuitive negative Poisson's ratio (NPR) behavior based on their geometric configuration. Cellular auxetics are light-weight and cost-effective materials that have the potential to demonstrate high strength and resilience under axial forces. Existing research on metallic auxetics is scarce and based mostly on analytical studies. Apparent NPR behavior of auxetics has also been linked to enhanced energy absorbing potential. A pilot study was undertaken to investigate and understand auxetic behavior in tubes constructed using ductile metals commonly found in structural applications i.e. steel and aluminum. The main objective was to establish whether performance enhancements could be obtained through auxetic behavior in ductile metal tubes. In addition, any potential benefits to auxetic performance due to base material plasticity were studied. These objectives were fulfilled by conducting an experimental and analytical investigation, the results of which are presented in this thesis.
The experimental program consisted of establishing a design methodology, manufacturing, and laboratory testing for tubular metallic specimens. A total of eight specimens were designed and manufactured comprising five steel and three aluminum. For each base metal, three different geometric configurations of cells were designed: one with a rectangular array of circular voids and two with void geometries based on the collapsed shape of circular cells in a design tube under uniaxial compressive stress. A parameter called the Deformation Ratio (DR) was introduced to quantify cell geometry. Designed tubes were manufactured via a six-axis laser cutting process. A custom-made test assembly was constructed and specimens were tested under reverse-cyclic uniaxial loading, with one exception. Digital Image Correlation (DIC) was used to acquire experimental strain data. The performance of the auxetic and non-auxetic tubular structures was evaluated based on the axial load-deformation characteristics, global deformations, and the specific energy absorption of the test specimens.
The experimental test results confirmed that ductile metal tubes with special collapsed cell geometries were capable of demonstrating auxetic behavior under the applied elastic and inelastic uniaxial strains; both tensile and compressive. Base material plasticity was observed to have an insignificant effect on the auxetic response. Experimental results suggested that the unique deformation mechanism precipitated by the auxetic cell geometries resulted in more stable deformed shapes. Stability in global deformed shapes was observed to increase with an increase in DR value. In addition, the unique auxetic mechanism demonstrated an ability to distribute radial plastic strains uniformly over the height of the auxetic pattern. As a result, plastic strains were experienced by a greater fraction of auxetic tubes; this enhanced the energy-dissipating properties of auxetic specimens in comparison to the tested non-auxetic tubes. Tubes with cell geometries associated with higher DR values exhibited greater energy absorption relative to the non-auxetic specimen. For the same base metal, auxetic specimens exhibited greater axial strength and effective strain range, when compared to their non-auxetic counterparts. The increased strength was partially attributed to the increased cell wall thickness of the auxetic specimens. However, the increased strain range was attributed to the rotation in unit cells induced by the unique auxetic geometry.
Experimental test data was used to validate the finite element (FE) and simplified macromechanical modeling approaches. These methods were adopted to develop design tools capable of replicating material performance and behavior as well as accurately predicting failure loads. Load-deformation response and effective Poisson's ratio behavior was established using FE models of as-built specimens, while simplified macromechanical equations were derived based on the equilibrium of forces to compute failure loads in tension. These equations relied on pattern geometry and measured experimental unit cell deformations. It was established that the manufacturing process had a detrimental effect on the properties of the aluminum specimens. Accordingly, empirical modifications were applied to the aluminum material model to capture this effect. FE models accurately replicated load-deformation behavior for both non-auxetic and auxetic specimens. Hence, the FE modeling approach was shown to be an effective tool for predicting material properties and response in ductile metal tubes without the need for experimental testing. The simplified strength equations also described material failure with reasonable accuracy, supporting their implementation as effective design tools to gauge tube strength. It is recommended that FE models be refined further through the addition of failure criteria and damage accumulation in material models.
The result of this study established that auxetic behavior could be induced in ductile metal tubes through the introduction of unique cell geometry, thereby making them highly tunable and capable of exhibiting variable mechanical properties. Owing to their deformation mechanism and NPR behavior, auxetic tubes demonstrated geometric stability at greater deformations, which highlighted their potential for use as structural elements in systems designed to deform while bearing extreme loads e.g earthquakes and blast events. Additionally, the capability of auxetic geometries to distribute strains uniformly along their length was linked to the potential development of energy-dissipating structural components. It was suggested that new knowledge acquired in this study about auxetic behavior in ductile metals could support the development of new structural systems or methods of structural control based on NPR behavior. Finally, recommendations for future research were presented, based on the expansion of research to study the effects of multiple loading regimes and parametric changes on auxeticity as well as additional mechanical characteristics e.g shear resistance.Master of Science
Special structures known as Auxetics have been studied that exhibit counterintuitive behavior based on their geometric configuration. The novel shapes and architecture of these structures allow them to deform such that they expand laterally in tension and contract laterally in compression; a property known as negative Poisson's ratio (NPR) which is rarely observed in naturally-occurring materials. Auxetic materials demonstrate mechanical properties such as high resilience, indentation resistance, and energy-absorption. An experimental and analytical study was undertaken to explore the beneficial properties of auxetic behavior, along with the effect of inelastic deformations in ductile metal auxetics. To this end, tubular test specimens, made with steel and aluminum, were designed and manufactured. To achieve auxetic behavior, a unique array of collapsed cells was cut out from metal tubes using a laser cutting process. Subsequently, specimens were tested in the laboratory under cyclic and monotonic loads. Experimental results indicate that tubes with auxetic geometries exhibited NPR behavior and a unique deformation mechanism based on the rotation of the unit cells. Owing to this mechanism, auxetic specimens possessed greater geometric stability under applied axial deformations, when compared to the tested non-auxetic specimens. The deformation mechanism was also responsible for a uniform distribution of strains along the length of the auxetic geometry which was linked to relatively better energy absorbing capacity than the non-auxetic tubes. Developed finite element (FE) models captured the response and behavior of all specimens with good accuracy. Derived simplified strength equations were also able to calculate the ultimate tensile failure loads for all specimens accurately. Both numerical methods demonstrated the potential to be utilized as design and evaluation tools for predicting material properties. Finally, recommendations to expand research, based on metal auxetic structures, were presented to further our understanding of auxetic behavior in ductile metals and to explore its benefits under varying loading regimes. Results from this research can be used to support the design of new structural systems or methods to control existing structures by exploiting NPR properties of ductile metal auxetics. Furthermore, energy-dissipating properties of metal auxetic materials may prove to be beneficial for structural applications under extreme loading conditions such as earthquakes and blasts.
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Luo, Lie, and 罗冽. "Uni-axial behavior of normal-strength concrete filled steel tubular columns with external confinement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49618210.
Full textAbstract:
This thesis proposes two forms of external confinement for concrete filled steel tubular (CFST) columns. The confinement efficiency is studied by examining the axial strength enhancement and ductility improvement of the CFST columns with external confinement.
Due to the heavy demand of confining steel to restore the column ductility in seismic regions, it is more efficient to confine these columns by hollow steel tube to form CFST column. Compared with transverse reinforcing steel, steel tube provides a stronger and more uniform confining pressure to the concrete core, and reduces the steel congestion problem for better concrete placing quality. The CFST columns are therefore characterised by higher strength, ductility and large energy absorption before failure.
However, a major shortcoming of CFST columns is the imperfect steelconcrete interface bonding occurred at the elastic stage as steel dilates more than concrete in compression. This adversely affects the confining effect and decreases the elastic modulus. To resolve the problem, it is proposed in this thesis to use external steel confinement in the forms of rings and ties to restrict the dilation of steel tube. For verification, a series of uni-axial compression test was performed on some CFST columns with external steel rings and ties. From the results, it was found that the external steel rings could improve both the axial strength and stiffness of the CFST columns significantly. However, the steel ties could not improve either the axial strength or elastic stiffness significantly. The confining efficiency was then investigated by comparing the strength of these confined-CFST columns with the reinforced concrete (RC) columns counterparts with the same concrete and steel volume. It is evident that the axial strength of CFST columns is much higher than the RC columns, which suggests that the application of CFST columns can utilise less construction materials and reduce the demolition waste.
A theoretical model is also proposed for predicting the axial strength of ring-confined CFST columns. Comparison between the predicted results and the test results obtained by the author and other researchers shows that the proposed model gives good estimation for both unconfined and confined CFST columns.published_or_final_version
Civil Engineering
Master
Master of Philosophy
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Chao, Min. "The design and behaviour of concrete filled steel tubular beam-columns /." View thesis View thesis, 2000. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030429.154344/index.html.
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Kabir, MD H. "Environmental durability study of CFRP strengthened steel tubular structures under four-point bending." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/91853/1/MD_Kabir_Thesis.pdf.
Full textAbstract:
This research has studied the environmental durability of CFRP strengthened steel circular hollow section (CHS) member under cold weather and a marine environment at different temperatures experimentally and numerically under bending. A significant reduction of tensile strength was found for adhesives material in both environments. The cold weather and a marine environment adversely affected the durability by reducing strength and stiffness of CFRP strengthened CHS members. An embedded GFRP layer together with CFRP layers enhanced durability in marine environment. A suitable durability design factor has been proposed under both environments.
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Moor, Constantin. "Three dimensional analysis of steel portal frame buildings." Thesis, Queensland University of Technology, 1997. https://eprints.qut.edu.au/36010/1/36010_Moor_1997.pdf.
Full textAbstract:
The true strength and deflection behaviour of industrial and commercial
steel portal frame buildings is understood better if the effects of stiffness of
end frames and profiled steel claddings are included. The conventional
designs ignore these effects and are very much based on an idealised twodimensional
frame behaviour. This thesis describes an investigation into the
three-dimensional behaviour of steel portal frame buildings using computer
modelling and full scale tests.
The full scale tests of a 12 m x 12 m clad and unclad steel portal frame
building with true pinned and standard (normal) bases were conducted
under a range of design load cases which indicated that the observed
deflections and bending moments in the portal frames were considerably
different to those obtained from a two-dimensional analysis of frames
ignoring the effects of cladding and end frame rigidity. Three dimensional
analyses of the same building including these effects using the "equivalent
truss member'' theory were carried out and the results agreed well with full
scale test results. The cladding flexibility coefficient required for this
computer analysis was obtained from shear tests of 6 m x 6 m crest-fixed
trapezoidal steel claddings.
In both full scale tests and computer modelling, the stiffness of cladding and
end frames had a significant influence on moments and deflections of the
portal frames when Cross Wind load was considered. For the tested frame
these effects were equivalent to stiffening the column bases from pinned to
fixed conditions. However, for Longitudinal Wind and Live Loads, the results
showed that buildings with a flat roof slope (in this case 5° ) will not gain
from the presence of claddings and the differences in maximum moment and
deflections are insignificant when cladding action and rigidity of end frame
are considered. In the design of the common industrial and commercial buildings, Cross
Wind load is the governing load case. Therefore it is important that the
significant effects observed due to the presence of cladding and end frame
rigidity be taken into account in the analysis and design of these buildings.
There was a noticeable load transfer from the central frame to the gable
frame when claddings and end frame bracing were added to the building
considered in the full scale tests and three-dimensional computer analysis.
This increased the moments on the end gable frame, but decreased the
higher moments on the central frame, leading to a more balanced moment
and deflection distribution among these frames. It is expected that such a
three dimensional analysis and design method will lead to lighter steel
frames as the maximum moments are reduced. Therefore this method which
is based on the true building behaviour is recommended for Cross Wind
loads.
This design method as well as recent advances in the use of higher strength
materials, can lead to buildings with more slender members, larger spans
and thus larger deflections. As a result, unlike in the past, deflection criteria
may become more critical than strength and increasing the member sizes is
not always the best solution for limiting such problems. For this purpose the
use of appropriate deflection limits and a better understanding of the true
deflection behaviour of the buildings are important. This investigation has
shown that choosing the location of the points where the deflection is to be
limited is more important than limiting maximum deflections for the whole
building. Serviceability problems usually do not appear in members such as
columns or rafters, instead they appear in panels such as walls, partitions,
ceilings and claddings. In order to eliminate serviceability problems in the
buildings it is then necessary to consider the "Characteristic panel" concept
developed by the author of this thesis. As a result, it is important from a
serviceability point of view not to limit the maximum horizontal and vertical
deflections in portal frames buildings, but to consider appropriate
characteristic panels in the buildings and analysing their relative deflections
to limit their specific deformations.
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Machado, Rafael Ignacio. "Experimental investigation of steel tubed reinforced concrete columns." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19457.
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Farley, Gary L. "Energy-absorption capability of composite tubes and beams." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54523.
Full textAbstract:
In this study, the objective was to develop a method of predicting the energy-absorption capability of composite subfloor beam structures. Before it is possible to develop such an analysis capability, an in-depth understanding of the crushing process of composite materials must be achieved. Many variables affect the crushing process of composite structures, such as the constituent materials’ mechanical properties, specimen geometry, and crushing speed. A comprehensive experimental evaluation of tube specimens was conducted to develop insight into how composite structural elements crush and what are the controlling mechanisms
In this study, the four characteristic crushing modes, transverse shearing, brittle fracturing, lamina bending, and local buckling were identified and the mechanisms that control the crushing process defined. An in-depth understanding was developed of how material properties, affect energy-absorption capability. For example, an increase in fiber and matrix stiffness and failure strain can, depending upon the configuration of the tube, increase energy-absorption capability. An analysis to predict the energy-absorption capability of composite tube specimens was developed and verified. Good agreement between experiment and prediction was obtained.
Sine-wave and integrally stiffened composite beams were evaluated. Composite energy-absorbing beams crush in modes similar to tubular specimens that are made from the same material and have similar geometry. Energy-absorption trends of the composite beams are similar to energy-absorption trends from composite tube specimens. Composite beams are equal or superior energy absorbers to comparable geometry metallic beams. Finally, a simple and accurate method of predicting the energy-absorption capability of composite beams was developed. This analysis is based upon the energy-absorption capability of the beams’ constituent elements.Ph. D.
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Wheeler, A. T. "The behaviour of bolted moment end plate connections in rectangular hollow sections subjected to flexure." Phd thesis, Department of Civil Engineering, 1998. http://hdl.handle.net/2123/8669.
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Vieira, Rodrigo Cuberos 1983. "Análise numérica e experimental de ligações tubulares de aço do tipo luva parafusada." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258129.
Full textAbstract:
Orientador: João Alberto Venegas RequenaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho apresenta o estudo de um modelo de ligação inovador para emendas de perfis tubulares circulares, visando facilitar e baratear a montagem e fabricação das estruturas metálicas tubulares, além de proporcionar economia de tempo. A ligação estudada é composta por dois tubos externos submetidos à tração, conectados à um tubo interno, de diâmetro inferior aos tubos externos, por meio de parafusos alinhados que atravessam ambos os tubos externo e interno. Esta ligação pode ser utilizada como alternativa às ligações em flange, por ser mais simples e discreta. Foi realizada uma pesquisa bibliográfica sobre as prescrições de cálculo e publicações nacionais e internacionais referentes às ligações de perfis tubulares, não sendo encontrado nenhum processo de cálculo para as ligações tubulares em luva parafusada. Um modelo numérico da ligação foi desenvolvido com o programa de elementos finitos ANSYS v13.0, levando-se em consideração o contato entre os parafusos e os tubos. Esse modelo foi validado através da análise de resultados experimentais em escala real da ligação estudada. Os resultados numéricos e experimentais possibilitaram analisar o comportamento da ligação e seus modos de falha com as respectivas resistências. Com o modelo numérico validado, foi realizado um estudo paramétrico, permitindo compreender em detalhes quais os principais modos de falha da ligação, e quais os fatores que mais influenciam na sua resistência. Através desse estudo foi possível observar a necessidade de se levar em consideração no cálculo da resistência à ruptura da seção líquida, o coeficiente de redução da área líquida, Ct, para essa ligação, sendo proposto um processo para obtenção do mesmo, assim como da resistência da ligação à tração. Os resultados obtidos demonstraram o bom comportamento da ligação tubular em luva parafusada e a viabilidade de sua utilização submetida à tração, com parafusos alinhados
Abstract: This paper presents a study of an innovative connection model to splice circular hollow sections, which can be used for an easier and cheaper assembly and manufacture of tubular steel structures, besides providing time-saving. The proposed connection consists of two external tubes under tension, connected to an internal tube with smaller diameter than the external ones, and bolts passing by both tubes. This connection can be used as an alternative to flange connections, because it is simple and discreet. A bibliographic research on national and international codes and papers of tubular connections was carried out, and no design process for tubular bolted sleeve connections was found. A numerical model of the connection was developed with the finite element program ANSYS v13.0, considering the tubes and bolts contact. The numerical model was evaluated against experimental analyses results of the connection. The numerical and experimental results allowed the behavior analysis of this connection and its possible failure modes with their respective resistances. With the evaluated numerical model, a parametric study was carried out, allowing to understand the connection main failure modes, and what factors most influence their strength. With this study it was clear the need of the reduction coefficient, Ct, calculation for this connection, being proposed a process to determine the reduction coefficient and the tension strength for this connection. The results demonstrated the good behavior and feasibility of the tubular sleeve connection under tension, with bolts in line
Doutorado
Estruturas
Doutor em Engenharia Civil
30
Nagui, Alexander. "A comparative analysis of the resistance of tubular joints." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
The resistance of tubular joints is conventionally determined by the failure mode approach where strength formulae are often determined in a semi-empirical way. The European standard EN 1993-1-8 is under the revision with the goal to have a new version in 2020. The design equations for hollow section joints in Chapter 7 of EN 1993-1-8, which have been calibrated against available experimental results in the 80’s, are compared with the design formulae in the international standard ISO 14346. In ISO 14346, the design equations have been re-analysed, adopting the results of extensive numerical investigations initiated in the 90’s.
Considering that a new version of EN 1993-1-8 is being drafted, which aims at adaptation of the newest generation of design equation for tubular joints, a comparative study between the codes have been performed. The results showed that a significant inconsistency exists between current EN 1993-1-8 and ISO 14346. The difference in strength prediction by the standards in some design situations reaches around 400%, e.g. for RHS T, Y and X joints with small β ratios and high compressive chord stress. A selection of available experimental and numerical results, in general, showed a better agreement with ISO 14346. The recently proposed amendments and corrigenda on EN 1993-1-8 Chapter 7, by a group headed by Prof. Wardenier and Prof. Puthli, minimize the identified differences with ISO 14346 yet they adapt most recent research outcomes for hollow section joints. Another proposed method, based on the component approach, is proved to be applicable to determination of the resistance of tubular joints.
FE analyses preformed in this study confirmed the reduction of axial resistance of RHS X joints due to tensile axial chord stresses. Recommendations are given based on the numerical study on RHS full width T joints under in-plane bending moment with chords made of HSS.
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Minchillo, Daniela Grintaci Vasconcellos. "Estudo de ligações pinadas com chapa de topo para aplicações em estruturas metálicas treliçadas tubulares planas." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257814.
Full textAbstract:
Orientador: João Alberto Venegas RequenaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho apresenta o desenvolvimento de uma concepção estrutural para ligações de treliças metálicas tubulares de seção circular com chapa de topo através de um estudo teórico-experimental. Nesta concepção as extremidades das diagonais são superpostas e unidas por um único parafuso fazendo com que a ligação seja pinada. A colocação da chapa faz com que apareça uma excentricidade na ligação originando esforços adicionais na estrutura que são aqui avaliados. Como vantagem desta ligação, destaca-se o baixo custo de fabricação, a rapidez de montagem das treliças, facilidade de transporte e versatilidade no detalhamento das ponteiras das diagonais. Pode ser utilizada em ligações de treliças planas ou multiplanares. Foi realizado um levantamento bibliográfico nas prescrições de cálculo e demais publicações, nacionais e internacionais, para ligações de estruturas tubulares, e um programa experimental foi desenvolvido com objetivo de certificar a ligação e obter um procedimento adequado para o cálculo da sua resistência. A análise experimental possibilitou a avaliação dos efeitos localizados na ligação, a interação entre a chapa e o perfil tubular e a identificação dos mecanismos de colapso. Os resultados experimentais são comparados com os resultados numéricos, que consideram como parâmetros, a influência do comprimento e da espessura da chapa de topo na resistência, no modo de colapso e na distribuição de tensões na ligação. Um modelo numérico, calibrado pelos resultados da análise experimental, foi utilizado para uma análise paramétrica. Com os resultados desta análise foi proposta uma formulação para obtenção da resistência da ligação
Abstract: This work presents a theoretical and experimental study of a gusset plate connection for application in trusses with circular hollow sections. In this connection the diagonals edges are superimposed and joined together at the plate by a single bolt causing the connection to be pinned. The placement of the plate leads to an eccentricity, resulting in additional efforts in the connection that are evaluated. Some of the advantages of this connection are the low manufacturing costs, the quickly assembly of trusses, versatility in the detailing of the braces ends and can be used properly on uniplanar or multiplanar trusses. A literature review is performed on codes, prescriptions and other publications, national and international for tubular connections, and an experimental program is developed in order to certify and obtain an appropriate procedure to determine the connection resistance. The experimental analysis allowed the evaluation of the local effects, the interaction between the gusset plate and tubular section and the identification of the failure modes. The experimental results are compared with numerical results considering parameters such as the influence of the length and thickness of the gusset plate in the connection resistance, failure mode and stress distribution. A numerical model, validated by the results of experimental analysis, was used for parametric analysis. With the parametric results, an analytical expression is proposed to predict the connection resistance
Doutorado
Estruturas
Doutor em Engenharia Civil
32
Coelho, da Silva Catherine Souto Costa 1986. "Estudo de ligações pinadas com chapa de topo para aplicações em estruturas metálicas treliçadas tubulares multiplanares." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258128.
Full textAbstract:
Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: O objetivo deste trabalho é apresentar um tipo de ligação em treliças metálicas tubulares multiplanares de seção circular com chapa de topo. Nestas ligações as extremidades das diagonais são superpostas e unidas por um único parafuso fazendo com que a ligação seja pinada. A colocação da chapa de topo implica no aparecimento de uma excentricidade na ligação originando esforços adicionais na estrutura. Esse tipo de ligação tem como vantagem o baixo custo de fabricação, a rapidez de montagem das treliças, a facilidade de transporte e a versatilidade no detalhamento das ponteiras das diagonais. Foi realizado um levantamento bibliográfico nas prescrições de cálculo e demais publicações, nacionais e internacionais, para ligações de estruturas tubulares e encontrou-se um estudo para esse tipo de ligação, mas apenas analisando treliças planas. Para verificar o comportamento da ligação, serão analisados modelos numéricos desenvolvidos com o programa de elementos finitos ANSYS 14.0. Os resultados encontrados com esses modelos serão analisados e comparados com os resultados numéricos encontrados na pesquisa de ligação pinada com chapa em treliças tubulares planares para elaboração de um fator de correção entre os dois tipos de ligação
Abstract: This paper objective is to propose a connection type for tubular steel trusses with circular section, multiplanar and with gusset plate. In these connections the ends of the diagonals are overlapped and joined by a single pin resulting a pinned connection. The position of the gusset plate in the connections implies an eccentricity which results in additional efforts in the structure. The advantage of this connection type is the low manufacturing cost, the fast erection of trusses, the easier transportation and the versatility in the detailing constructive of the diagonals end. Survey in technical books, standards, manuals and scientific articles was made for tubular steel structures connection. In this survey was found a research for a similar type of connection, but in this there were only analysis of planar trusses. Numerical models using the commercial finite element software ANSYS 14.0 will be analyzed to check the connection. The results from these models will be analyzed and compared with numerical results in the bibliographic review about planar truss for preparation of a correction factor between the two types of connection. OBSERVAÇÃOA palavra gusset nas palavras chaves, título em inglês e no abstract devem ser grifadas em itálico
Mestrado
Estruturas e Geotécnica
Mestra em Engenharia Civil
33
Souza, Mauricio Guilherme Quilez. "Automação e integração CAD/CAE no projeto de estruturas metalicas, utilizando perfis tubulares." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257809.
Full textAbstract:
Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho tem como objetivo o desenvolvimento de códigos de computador que têm a finalidade de automatizar as etapas principais de um projeto de estruturas metálicas através das linguagens AutoLISP e Delphi5. Os projetos de estruturas metálicas em estudo são os de coberturas com treliças planas constituídas de barras com perfis tubulares laminados sem costuras e seus contraventamentos. Estes perfis tubulares, ainda pouco utilizados em estruturas planas no Brasil, vêm sendo disseminados através do uso de programas que ajudam os engenheiros a utilizá-los adequadamente em seus projetos tendo em vista que resultam em estruturas mais leves e de fácil fabricação. Desta forma, houve a necessidade de desenvolver um sistema CAD/CAE, para automatizar a geração das geometrias das estruturas planas, além das representações gráficas do sistema geral tridimensional de contraventamentos da estrutura - CAD; exportar os dados para um programa integrado que realiza um processo otimizado de toda a análise estrutural e dimensionamento - CAE e, finalmente, retornar os dados processados para o ambiente CAD, para realizar o detalhamento automático das ligações da estrutura treliçada analisada. Todos os procedimentos adotados para automação dos projetos seguem recomendações de normas técnicas brasileiras principalmente a NBR8800/1986
Abstract: This work has as objective to show a software that have the goal to automate the main stages of a steel structural design, using AutoLISP and Delphi5 languages. The steel structural designs in case are the roofs formed by plane trusses made by hollow sections frames. These hollow steel sections, which are not highly used in plane structures in Brazil, are being disseminated by the use of softwares that help civil engineers to use them correctly in their designs, in view of that they result in less weighted and easy manufactured structures. So, there is the necessity to develop a CAD/CAE system, that will automate the generation of the geometries from plane structures and the graphical designs from the three-dimentional general system - CAD; also, we have the necessity to export the data to an integrated computer program that executes an optimized process from the entire structural analysis and design - CAE; and, finaly, to return the proceeded data back to CAD environment, to draw the automatic details from the connections of the analyzed structure. All the procedures and methods used to automate the design follows the specifications of Brazilian Design Codes, mainly the NBR-8800/1986
Mestrado
Estruturas
Mestre em Engenharia Civil
34
Souza, Alex Sander Clemente de. "Contribuição ao estudo das estruturas metálicas espaciais." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-26022018-134729/.
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Este trabalho apresenta um estudo sobre as estruturas metálicas espaciais abordando os seguintes aspectos: histórico e desenvolvimento, tipos, vantagens do sistema tridimensional e comportamento estrutural. Atenção especial é dispensada às tipologias de treliças espaciais mais comuns no Brasil, formadas por tubos circulares com variações de inércia nas extremidades. A influência da variação de inércia nas extremidades das barras no comportamento destes elementos isoladamente (resistência à compressão) e comportamento global da estrutura, foi estudada via elementos finitos. Descrevem-se vários sistemas de ligações patenteados utilizados em outros países e os comumente usados no Brasil. Apresentam-se resultados experimentais e teóricos de uma treliça espacial com dimensões em planta de 7,5 x 7,5 m. Na análise teórica foram considerados a variação de inércia nas barras e os efeitos da não linearidade geométrica. Analisou-se também, com as mesmas considerações anteriores, modelos de treliças espaciais de dimensões maiores que o modelo ensaiado.This work presents a study of space steel structures including the following aspects: history and development, types, advantages of three-dimensional system and structural behaviour. It is given special attention to the most common types of space trusses in Brazil, composed of tubular sections bars with flattened ends. The influence of the variable stiffness on each element\'s behaviour (compressive strength) and on the global structural behaviour has been studied with the use of finite elements. Various patent connection systems used in other countries and those commonly used in Brazil are described. Experimental and theoretical results of a 7,5 m-long by 7,5 m-wide space truss are presented. In the theoretical analysis, variable stiffness and effects of geometrical non-linearity have been considered. Still applying the above considerations, larger space truss models have been also analysed.
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Plodpradista, Wisuwat. "Study of tubular linear induction motor for pneumatic capsule pipeline system /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3052209.
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Simões, Renato. "Efeito do confinamento em pilares mistos curtos de aço e concreto." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257860.
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Orientadores: Ana Elisabete Paganelli Guimarães de Avila Jacintho, João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: O emprego das estruturas mistas está cada vez mais comum, pois as mesmas apresentam vantagens construtivas em relação às estruturas convencionais de aço ou concreto. Este sistema construtivo, ainda é novidade em muitos países, porém Japão e Estados Unidos da América que já fazem uso, atualmente estão desenvolvendo novas pesquisas para o aperfeiçoamento das técnicas de projeto e construção de tal sistema. Esta pesquisa visa estudar o efeito do confinamento presente nos pilares mistos tubulares circulares preenchidos com concreto verificando, assim, como e quanto há de interação entre o tubo metálico e o concreto de preenchimento sob o efeito de força axial de compressão comparando-os assim com os métodos de dimensionamento propostos pelas normas. O projeto de revisão da NBR 8800:2003 e o Eurocode 4:1994, na consideração do efeito do confinamento apresentam um dimensionamento inseguro, entretanto a especificação americana AISC ASD:1999, que não considera o confinamento apresenta resultados mais próximos daqueles encontrados nesta pesquisa. Nas comparações dos resultados experimentais com os resultados propostos pelas normas é notável a grande importância de uma consideração mais detalhada no dimensionamento da relação diâmetro / espessura das seções mistas. Nesta pesquisa o comportamento das seções mistas foi diferente para cada relação diâmetro / espessura proposta
Abstract: Not informed.
Mestrado
Estruturas
Mestre em Engenharia Civil
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Kreisel, Martin. "Ocelová konstrukce sportovní haly." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226068.
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Steel structure of the sports hall in the city of Olomouc. Specific design is chosen from three options. Plan dimensions of 45 x 60 m. Height 12.5 m. Structure is composed of rolled profiles and tubular steel. Two trusses girders are fixed by knuckle joints on pillars. Static check is performed using the program SCIA ENGINEER 2009 and the manual review.
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Jiao, Hui 1963. "The behaviour of very high strength (VHS) members and welded connections." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9417.
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Forti, Nadia Cazarim da Silva. "Estudo parametrico de estruturas tubulares com ligações multiplanares." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257812.
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Orientador: João Alberto Venegas RequenaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho apresenta um estudo paramétrico comparativo de ligações do tipo K e KK utilizando perfis tubulares circulares com afastamento entre diagonais e carregadas simetricamente. Para se comparar as ligações, foi desenvolvido um modelo numérico através do programa comercial de elementos finitos Ansys. Também foram desenvolvidos dois programas auxiliares para facilitar o estudo paramétrico. Foram analisadas 55 ligações do tipo KK e suas correspondentes K, comparando-se suas resistências. O objetivo deste trabalho é propor um critério objetivo para definir os modos de falha (1 e 2) da ligação tipo KK baseado na deformação diametral do banzo. O modo de falha 1 ocorre quando um par de diagonais vizinhas, carregadas no mesmo sentido, empurra ou puxa, a parede do banzo e no segundo, chamado modo 2 acontece uma deformação diametral da parede do banzo na região entre as diagonais vizinhas, criando quinas e dobras entre essas diagonais. Outro objetivo é estabelece uma demarcação do limite entre os dois modos de falha como uma função do afastamento transversal entre as diagonais. Os resultados permitiram o desenvolvimento de equações que preveem as resistências das ligações tipo KK, para os modos de falha 1 e 2 (plastificação da parede do banzo), a partir da resistência da ligação tipo K correspondente
Abstract: This work presents a parametric study of K and KK tubular steel connection. Gap connections with symmetric loading are analyzed. A numerical model using the commercial finite element software Ansys is proposed to compare K and KK connection resistances. Two auxiliary softwares are developed for setting the numerical model and to post-process results. A set of 55 KK connections and their correspondent K connections are analyzed and their resistances are compared. The objective of this work is purpose define the failure mode (1 or 2) of KK connections. This criteria is based on the chord diametric deformation. The results allowed the definition of limit values in function of the transversal gap for determining the connection failure mode. The connection resistance obtained in the parametric study allowed the development of an analytical expression which predict the KK connections resistance from the resistance of its correspondent K connection
Doutorado
Estruturas
Doutor em Engenharia Civil
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Vendrame, Adriano Márcio. "Contribuição ao estudo das cúpulas treliçadas utilizando elementos tubulares em aço." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-14122017-154316/.
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Este trabalho apresenta um estudo sobre as estruturas espaciais em forma de cúpulas abordando os seguintes aspectos: histórico, desenvolvimento, descrição dos tipos mais utilizados, comportamento, análise e alguns aspectos de projeto e execução. Enfatizam-se as cúpulas constituídas por elementos tubulares com seção transversal circular e, em particular, as que necessitam da estampagem da extremidade de seus elementos para confecção do sistema de ligação. Descrevem-se vários sistemas de ligação utilizados em vários países e os utilizados no Brasil. A influência da variação de inércia causada pela estampagem das barras foi estudada via método dos elementos finitos com a devida modelagem da região afetada. A região modelada foi inserida em uma treliça espacial plana e seus resultados comparados com resultados experimentais desta estrutura. Apresentam-se também, os procedimentos básicos para elaboração do projeto de uma cúpula considerando as hipóteses utilizadas nos escritório de projeto, ou seja, comportamento elástico linear e nós rotulados. Para a mesma estrutura, um breve estudo sobre ruína progressiva, é apresentado.This research presents a study about dome space structures about the following aspects: history, development, description of the more utilized types, behavior, analysis and some project and design aspects. It\'s emphasized the tubular element domes with circular section, particularly, those which need stamping at the end to wake the joint system. It\'s described many joint systems which are utilized in several countries and also in Brazil. The variable stiffness influence caused by the stamping on the bar ends was studied using the Finite Element Method by a suitable model of the affected region. The modeled region was inserted into a plane space truss and the analysis results were compared to the experimental values. It\'s also presented the basic procedures to dome project development, considering linear-static behavior. For the same model, a short study about failure downfall is presented.
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Pereira, Daniel Henrique Fidelis. "Análise do comportamento estrutural de ligações em aço entre viga de seção I e pilar de seção tubular circular." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-11122013-101943/.
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Esta pesquisa consiste de uma investigação acerca do comportamento estrutural de ligações entre viga de seção I e pilar de seção tubular circular em situações de pilar de canto e de pilar solicitado por quatro vigas simultaneamente (pilar central). A associação entre a viga de seção I e o pilar de seção tubular circular remete à análise de ligações com comportamento complexo. A partir da análise numérica, via Método dos Elementos Finitos com os softwares ANSYS® e TrueGrid® foi avaliado o comportamento momento-rotação e parâmetros como resistência, rigidez inicial e ductilidade das ligações. Foram analisadas as tipologias de ligação soldada e ligação com a presença do diafragma externo como mecanismo de enrijecimento. Avaliou-se a influência de 6 variáveis, sendo o comprimento da viga, a espessura do pilar, a força aplicada nas vigas dispostas ortogonalmente, a compressão axial do pilar, a espessura do diafragma e o diâmetro dos parafusos do diafragma totalizando 20 modelos numéricos. O aumento da espessura da seção do pilar e a força aplicada simultaneamente nas 4 vigas representou uma melhoria na resistência e rigidez inicial das ligações soldadas. A redução do diâmetro dos parafusos do diafragma foi a principal variável capaz de influenciar negativamente as propriedades de rigidez inicial e resistência das ligações com o diafragma. Todos os modelos analisados apresentaram comportamento semi-rígido segundo o Eurocode 3 (2005). O dimensionamento analítico pelo Eurocode 3 (2005) e por Winkel (1998) apresentou boa aproximação com os resultados da análise numérica. A obtenção da resistência das ligações com diafragma pelo método das componentes apresentou resultados, em média, 20% inferiores ao verificado na modelagem numérica. A utilização do diafragma como mecanismo de enrijecimento das ligações mostrou-se eficiente. As ligações soldadas apresentaram maior ductilidade comparada às com diafragma. O aumento da espessura do pilar nas ligações soldadas demonstrou-se uma alternativa eficaz no enrijecimento das ligações.This research consists of an investigation above the structural behavior of connections between I-beam and circular hollow section (CHS) columns in situation of corner columns and column loaded by 4 beams simultaneously (inside columns). The association between the I-beam and the CHS column presupposes the analysis of connections with a complex structural behavior. Based on a numerical analysis, using the Finite Element Method with ANSYS® and TrueGrid® softwares, the connection parameters like strength, stiffness and ductility was evaluated. The typologies of welded connections and connections with an external diaphragm was analyzed. An amount of 6 variables (beam length, column thickness, force applied on the beams, compression of the column, diaphragm thickness and bolt diameter) was analyzed in a total of 20 numerical specimens. The increase of the column thickness and the force applied simultaneously on the 4 beam ends culminated on a substantial improvement on strength and stiffness of the welded connections. The reduction of the diaphragm bolts diameter was the main reason for the negatively influence on strength and stiffness properties of the diaphragm connections. All specimens presented a semirigid behavior according to the Eurocode 3 (2005). The analytical design, based on the Eurocode 3 (2005) and Winkel (1998), obtained good results in terms of connections strength compared with the numerical analysis. The obtainment of the connections strength with the component method demonstrated results 20% less than numerical analysis. The external diaphragm as a stiffening mechanism showed effective. The welded connections presented more ductility than the diaphragm ones. The increase on the column thickness demonstrated an effective alternative for the connection stiffening.
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Afshan, Sheida. "Structural behaviour of cold-formed stainless steel tubular members." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23660.
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This thesis examines the behaviour of cold-formed stainless steel tubular structural members, with an emphasis on ferritic stainless steels. Owing to the high comparative expense of stainless steel relative to traditional carbon steel, this study aims to identify and develop means of utilising the material more efficiently. A comprehensive material test programme was carried out as part of an extensive study into the prediction of strength enhancements in cold-formed structural sections that arise during production. Material tests on a total of 51 flat coupons and 28 corner coupons, extracted from a total of 18 cross-sections formed from a wide range of materials, were performed. A new, simple and universal predictive model for harnessing the cold-formed induced strength enhancements was developed which offers, on average, 19% and 36% strength enhancements for the cross-section flat faces and corner regions, respectively, relative to the strength of the unformed material. Ferritic stainless steels, having no or very low nickel content, offer a more viable alternative for structural applications to the more commonly used austenitic stainless steels, reducing both the level and variability of the initial material cost. There is currently limited information available on the structural performance of this type of stainless steel. Therefore, to overcome this limitation, a series of material, cross-section and member tests have been performed on two ferritic grades - EN 1.4003 and EN 1.4509. The experimental results were used to assess the applicability of the current codified design provisions to ferritic stainless steel structural components. Moreover, the elevated temperature performance of ferritic stainless steels, covering the material response and the flexural buckling behaviour, was investigated through analysis of experimental and numerical results, leading to proposals for suitable design recommendations. Finally, simplifications and refinements to the recently developed continuous strength method (CSM) were made. Comparison of the predicted capacities with over 140 collected test results on stainless steel stub columns and cross-sections in bending shows that the CSM offers improved accuracy and reduced scatter relative to the current design methods. The reliability of the approach has been demonstrated by statistical analyses, enabling its use in structural design standards.
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Lima, JoÃo Baptista Cardoso Athayde. "ContribuiÃÃes para otimizaÃÃo estrutural de torres tubulares de aÃo para turbinas eÃlicas." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8131.
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nÃo hÃAs grandes questÃes do mundo globalizado tÃm passado, necessariamente, pelos temas ligados à sustentabilidade, energia limpa, exploraÃÃo do meio ambiente de forma ecologicamente correta e inovaÃÃo tecnolÃgica para manter o planeta saudÃvel. Nesse contexto, a energia eÃlica vem se destacando, principalmente na regiÃo Nordeste do Brasil, pelo grande potencial dos ventos e as caracterÃsticas de renovabilidade e complementaridade com a energia das hidrelÃtricas. As torres, que representam parcela significativa do custo do sistema, tendem a crescer buscando ventos com maiores velocidade e permitindo a utilizaÃÃo de turbinas eÃlicas de maior capacidade de geraÃÃo, acentuando-se a sua importÃncia como elemento estrutural do sistema. O objetivo geral deste trabalho à formular um modelo de otimizaÃÃo de torres tubulares de aÃo, composta de segmentos em tronco de cone. Busca-se a soluÃÃo de peso mÃnimo, tendo como variÃveis de projeto os diÃmetros externos e as espessuras de chapa caracterÃsticas de cada segmento. RestriÃÃes relativas à resistÃncia, à estabilidade e rigidez sÃo impostas com base em normas brasileiras. RestriÃÃes relativas à frequÃncia natural, a limitaÃÃes de transporte e geomÃtricas sÃo tambÃm requeridas. O conjunto nacele/rotor à modelado como uma massa rÃgida fixada no topo da torre, sem rotaÃÃo, e o carregamento atuante na estrutura inclui os pesos da torre e do conjunto rotor/nacele, o efeito estÃtico da aÃÃo do vento sobre a torre e as pÃs do rotor. A concepÃÃo de anÃlise adota modelo de viga engastada na base e livre no topo e emprega uma formulaÃÃo nÃo linear geomÃtrica pelo MÃtodo de Elementos finitos usando um programa em C++. O modelo de otimizaÃÃo foi implementado no MATLAB e, devido à natureza discreta das variÃveis de projeto e Ãs descontinuidades de funÃÃes de restriÃÃo e de suas derivadas, utilizam-se algoritmos genÃticos na soluÃÃo. Buscas na vizinhanÃa das soluÃÃes discretas sÃo realizadas usando um algoritmo baseado em informaÃÃo de gradiente (fmincon do MATLAB). AplicaÃÃes para vÃrias alturas de torre sÃo feitas, incluindo comparaÃÃes com uma torre cilÃndrica para validaÃÃo do modelo. Os resultados sÃo analisados frente aos de outros modelos da literatura. Os conceitos de projeto de torre rÃgida e flexÃvel sÃo discutidos relaxando-se as restriÃÃes de rigidez e de frequÃncia. SoluÃÃes obtidas sÃo analisadas usando elementos de casca do programa de anÃlise ABAQUS para verificaÃÃo de tensÃes e deslocamentos
The main subjects of the globalized world have passed necessarily by issues related to sustainability, clean energy, environment exploration in an ecologically correct way, and technology innovation to maintain a healthy planet. In this context, the wind has been highlighting, especially in the Northeast of Brazil, because of the large wind potential and the characteristics of renewability and complementarily with hydropower energy. The towers represent significant portion of the cost of the system, tends to grow seeking greatest wind speeds and allowing the use of wind turbines with bigger production capacity, emphasizing its importance as a structural element of the system. The main objective of this work is to formulate an optimization model of tubular steel towers, composed of segments in truncated cone. The aim is a minimum weight solution, having outer diameters and plate thicknesses characteristics of each segment as design variables. Constraints related to strength, stability and stiffness are imposed based on Brazilian codes. Constraints related to natural frequency, the limitations of transport and geometry are also required. The nacelle/rotor conjunct is modeled as a rigid mass attached to the top of the tower, without rotation, and the loading acting on the structure includes the weights of the tower and the nacelle/rotor conjunct, the static wind effect on the tower and on rotor blades. The analysis model adopts cantilever beam and employs a formulation for geometric nonlinear finite element method using a C++ program. The optimization model was implemented in MATLAB and due to the discrete nature of the design variables and the discontinuities of the constraint functions and their gradients we use genetic algorithms in the solution. Searches in the neighborhood of the discrete solutions are performed using a gradient based algorithm (fmincon in MATLAB). Applications to several tower heights are made, including comparisons with a cylindrical tower to validate the model. The results are analyzed against others models in the literature. The concepts of rigid and flexible tower project are discussed relaxing their stiffness and frequency constraints. Solutions obtained are analyzed using shell elements of ABAQUS analysis program to check tensions and displacements
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Folster, Kaylee. "Influence of geometry on the dynamic behaviour of steel tubular towers for onshore wind turbines." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25282.
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South Africa has recently experienced challenges regarding electricity consumption and availability. As part of the country's Integrated Resource Plan, these challenges are to be addressed. This involves a 20 year plan which aims to increase electricity supply capacity as well as reduce the reliance on coal power as part of the global trend to become more environmentally friendly. Wind power, specifically, is to account for a large portion of the renewable energy that is expected to become available by 2030. This results in the need for the understanding of wind turbine design by South African engineers. The dynamic analysis of wind turbine structures, is of particular interest to Civil Engineers. Wind turbine towers are recently of the monopole or tubular type tower, predominantly constructed of either concrete or steel or a combination of both. Steel tubular towers above a height of 80m are generally not recommended for wind turbines owing to cost concerns as well as difficulties in meeting dynamic behaviour requirements. Concrete towers and steel-concrete hybrid towers are recommended for this height regime. The aim of this study was to assess the prospective use of steel tubular towers of varying geometric shape for wind turbines with tower heights of 80m or greater. The study focussed on the analysis of natural frequency and assessing the applicability of steel tubular towers of geometric shapes that have not been previously explored or reported. The turbine of choice for this study was the Vestas V112 3MW type as this is one of the most commonly used and more efficient turbines for towers of this height regime. The results of this study showed that steel monopole towers of heights of 80m and more are still viable options for wind turbine towers. Various geometric tower cases of heights varying from 80m to 120m, produced acceptable fundamental natural frequencies within the allowable frequency range for a Vestas V112 3MW turbine.
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Fidalgo, Augusto Madrigali 1989. "Estudo teórico e numérico do comportamento de ligações tipo flange circular para estruturas tubulares de aço." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258130.
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Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho consiste no estudo teórico e numérico de uma ligação flange, solicitada inicialmente por força axial de tração e, em um segundo momento, por uma força excêntrica de tração. Essa ligação é usada em estruturas metálicas tubulares para emenda de barras e, especificamente nesse projeto, em perfis tubulares circulares. É uma ligação parafusada e soldada, com flanges circulares nas duas extremidades das barras, soldados de forma continua e sem furo no meio da placa, também chamada de "Blank Flange", conectando as barras. A grande parte das bibliografias e normas atuais preveem para esse tipo de ligação o dimensionamento apenas para solicitação de força axial de tração, dentre as estudadas, apenas uma prevê o dimensionamento com solicitação excêntrica. Assim, nesse trabalho foi feita uma modelagem numérica, usando o software Ansys, para estudar o comportamento dessa ligação frente à solicitação axial de tração, verificando o mecanismo do efeito "Prying", ou efeito alavanca, e sua influência na resistência da peça. Usando esse modelo, foi verificada a validade das formulações para a tração, o mecanismo de funcionamento da ligação e a possibilidade de otimização do cálculo, que hoje é feito com fórmulas empíricas, das quais não se conhece os dados de ensaios. Por fim, uma vez calibrado o modelo numérico para tração e verificado o cálculo proposto, ele foi ajustado para simular o flange submetido à flexo-tração, e com isso seu comportamento foi estudado e proposta uma formulação para esse dimensionamento
Abstract: The research is about a theoretical and numerical analysis of flange connection, initially subject to axial tensile load, and then to an eccentric tensile load. This kind of joint is used in hollow steel structures, and specifically in this work, using circular hollow section. Flange is a bolted and welded connection, which both tubes are welded on continuous circular plates, without holes, called Blank Flange, and this plates are bolted together. Most bibliography and codes, used in this research, have only the axial tensile design for flange, just one of them have the flexure tensile one. Because of that, this research proposed a numerical model in Ansys, to study how this joint behave subject to axial tensile load, checking prying effect, or cantilever effect, and its influence in joint resistance. Using this model, the axial tensile design was validated numerically, joints behavior was analyzed and the possibility to optimized the actual design, which is based on empirical equations. Therefore, once the numerical model for axial tensile load and it¿s design was calibrated, this was changed to simulate eccentric tensile load, to study its behavior and propose a design
Mestrado
Estruturas
Mestre em Engenharia Civil
46
Hu, Yu. "Improvement of the structural response of steel tubular wind turbine towers by means of stiffeners." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6227/.
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In the thesis the structural response of steel tubular wind turbine towers with various design configurations is analysed using FEM modelling. First, a structural response simulation model was validated by comparison with the existing experimental data. This was then followed with a mesh density sensitivity analysis to obtain the optimum element size. Based on this outcome, towers of various heights between 50-250m are considered and investigated with three different design options as follows: (i) thick walled tower with internal horizontal stiffening rings, (ii) thick walled tower without stiffening rings and (iii) thin walled tower with stiffening rings. Based on this analysis, weight reduction ratios are examined in relation to the horizontal sway and von Mises stress increase ratios in order to identify a more efficient design approach between reducing the wall thickness and adopting internal stiffeners. All studied design solutions satisfy the strength and serviceability requirements as specified by the design codes of practice.
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Sepúlveda, Bárbara Daniela Giorgini 1986. "Influência das ligações no dimensionamento das estruturas tubulares circulares de aço treliçadas." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258631.
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Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-23T22:44:13Z (GMT). No. of bitstreams: 1 Sepulveda_BarbaraDanielaGiorgini_M.pdf: 5435418 bytes, checksum: 5d55af89b27e919b7c819e297b4cf056 (MD5) Previous issue date: 2013
Resumo: Este artigo apresenta o estudo da influência das ligações no comportamento das estruturas treliçadas compostas por perfis tubulares de aço. As ligações em treliças de aço são normalmente projetadas para união de barras por meio de chapas que garantam a transmissão e equilíbrio das forças. No caso em particular de treliças que utilizam perfis tubulares de aço as ligações são projetadas sem chapas. As barras são unidas diretamente por meio de soldas nos contatos dos perfis que são cortados geometricamente exatos para o ajuste da ligação. Este procedimento aumenta a produtividade de fabricação além de dar um aspecto visual melhor para a estrutura. Dependendo da geometria da ligação podem ocorrer excentricidades dos eixos provocando a introdução de momentos fletores, que quando não puderem ser evitados, devem ser levados em consideração não só no cálculo da ligação como também na determinação dos esforços da treliça. Outro aspecto importante é a análise do colapso da ligação que pode ocorrer quando uma barra é associada à outra de forma inadequada na ligação direta, sendo variados os tipos de falhas. Portanto, será analisada a influência das ligações no comportamento da estrutura a partir de gráficos baseado no estudo das equações de força resistente das ligações tubulares circulares. Este estudo gráfico permitiu a criação do processo de cálculo, denominado Processo Simplificado, que orientam para as combinações de perfis que atendam as exigências geométricas e de força resistente das ligações durante o dimensionamento de barras. O processo é baseado em de tabelas de cálculo desenvolvidas para a orientação de um bom projeto de estrutura treliçada considerando ou evitando estas influências sem onerar o projeto final
Abstract: This paper presents the study of connections influence in the behavior of hollow sections truss structures. Joints in steel trusses are usually designed considering sheets that will ensure the transmission and balance of forces. In particular case of trusses using hollow sections steel connections are designed without plates. The beams are directly welded to steel sections which are geometrically cut to fit the joint. This increases manufacturing productivity in addition to give the structure a better visual appearance. Axes eccentricities can occur depending on connection geometry resulting in introduction of bending moments. When this eccentricity cannot be avoided, it has to be taken into account in joint design and also in determining truss efforts. Another important aspect is analysis joint collapse which can occur when a beam is improperly associated to another beam, which can produce many kinds of fails. Therefore, graphics analyses were studied based on circular hollow sections joint strength equations that show the influence of joints on structures. The Simplified Process, created after graphics studies, shows the valid combinations of circular hollow sections geometry and strength during beam structure design verification. This process is based on tables developed to orient a good truss project considering or avoiding this influences without raising budget on final design
Mestrado
Estruturas e Geotécnica
Mestra em Engenharia Civil
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Tao, Yunxiang. "Advanced numerical analysis and fire testing of cold-formed steel hollow section stud walls." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/226716/1/Yunxiang_Tao_Thesis.pdf.
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This research investigated the behaviour of light gauge steel frame walls made of cold-formed steel hollow section studs under both ambient and fire conditions using full scale experimental and advanced numerical studies. It developed and improved new structural and fire design rules for hollow section stud walls that can be included in the Australian steel structures standard. Importantly, it showed that such wall systems have superior fire resistance than conventional wall systems used currently. Overall, this research has sufficiently improved the knowledge of light steel walls made of hollow section studs in fire, enabling structurally efficient and safer designs.
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Vieira, Rosilene de Fátima 1968. "Um estudo sobre ligações do tipo YT de barras afastadas de seções tubulares circulares laminadas de aço." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257808.
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Orientadores: João Alberto Venegas Requena, Arlene Maria Sarmanho FreitasTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este trabalho apresenta os resultados de uma análise teórica, experimental e numérica, de uma ligação YT utilizada em estruturas metálicas planas, tendo como ponto de partida a verificação do comportamento global da ligação. Será avaliada uma ligação de treliça do tipo YT com diferentes afastamentos entre as barras "gap". As barras que compõem a ligação, aqui apresentada, possuem seções transversais tubulares circulares, vazadas de parede fina, soldadas entre si. O modo de colapso da ligação foi devido à plastificação da parede do banzo (uma diagonal tracionando a parede do banzo e o montante comprimindo). Um efeito de abaulamento da seção transversal do banzo na região do afastamento foi observado. O dimensionamento da ligação segue o Método dos Estados Limites, no qual as resistências de cálculo são verificadas. As barras envolvidas nesta ligação também sofrem a influência de momentos fletores. O estudo foi realizado através de uma análise comparativa entre uma solução analítica fornecida por normas técnicas internacionais, uma análise experimental e uma modelagem numérica utilizando-se o programa Ansys. A modelagem numérica, tendo como referência a análise experimental, foi realizada utilizando os elementos SHELL 181 e SHELL63, com 4 nós por elemento. Foram realizadas análises paramétricas com variação do afastamento, "gap"J entre os eixos do montante e da diagonal, observando-se que a resistência da ligação cresce com a redução do "gap". A finalidade deste estudo foi o entendimento do comportamento desta ligação, possibilitando assim, a disseminação desta concepção estrutural ainda pouco explorada_no Brasil para viabilizar a execução de projetos otimizados
Abstract: This work presents the theoretical, experimental and numerical analyses using of a YT joint used in plane trusses steel, having as the beginning point the verification of the global behavior of the connection. A connection of truss of YT type with gap members was evaluated. The members that compose the connection, presented here, have circular tubular cross sections welded among themselves. The failure mode of the connection was due to the plastic failure of the chord face (one web member pushing its face whereas the brace is pulling it out). An cambered effect of the chord cross section on the gap region was noted. The connection design follows the Limit State Design, in which the calculated resistance is verified. The involved members in this connection are also subjected the influence from add bendings. The study was developed by through a comparative analysis considering an analytical. solution supplied by intemational technical codes, an experimental analysis and a numerical modeling using with Ansys software. In the numerical study, the 4-node SHELL 181 and SHELL63 element was used to model the connection. The purpose of this study is to understand this connection mechanical behavior, thus contributing to possible the dissemination of this structural. conception still not explored so much in Brazil yet and to to be feasible the execution of optimized projects
Doutorado
Estruturas
Doutor em Engenharia Civil
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ARAÚJO, Marcia Suzanna Dutra Abreu de. "Análise numérica sobre o comportamento ao fogo de pilares tubulares em aço." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18591.
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Dissertação - Márcia Suzanna.pdf: 3055575 bytes, checksum: 6bc6b37e92f9ee9ac23e94abb75174c3 (MD5)Made available in DSpace on 2017-04-19T15:38:12Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Márcia Suzanna.pdf: 3055575 bytes, checksum: 6bc6b37e92f9ee9ac23e94abb75174c3 (MD5) Previous issue date: 2016-09-23
Atualmente, especialmente no Brasil, tem crescido a preocupação com o desempenho de estruturas sujeitas à ação de incêndios, devido aos riscos inerentes dessa situação. Por exemplo, somente em Pernambuco, no triênio 2011-2013, o Corpo de Bombeiros registrou a ocorrência média de 1600 incêndios/ano em edificações (residenciais, comerciais ou industriais). Catástrofes associadas a incêndios como esses podem resultar em elevados prejuízos financeiros, perda de patrimônio histórico/cultural, danos ao meio ambiente, além das irreparáveis perdas de vidas humanas, como as registradas na boate Kiss em Santa Maria – RS em 2013. Este trabalho visou analisar o desempenho ao fogo de pilares em aço, devido à grande relevância desse elemento para o projeto estrutural e, consequentemente, para segurança da edificação. Diversos fatores influenciam o comportamento de pilares em situação de incêndio, por exemplo: o esforço solicitante do serviço ao qual o pilar está submetido, a forma e dimensões da seção transversal, o índice de esbeltez do pilar e o comportamento das propriedades mecânicas e características dos materiais sob temperaturas elevadas. Devido à complexidade da influência dos parâmetros envolvidos na análise de estruturas em situação de incêndio, a resistência ao fogo dos elementos estruturais, como pilares, é determinada experimentalmente. No entanto, em geral, esses ensaios são caros e difíceis de serem realizados. Isso, por muitas vezes, inviabiliza o estudo de um número maior de amostras, não permitindo um melhor entendimento do problema. Nesse sentido, os modelos numéricos são de extrema importância para o estudo de estruturas em situação de incêndio, uma vez que tem sido possível reproduzi-los em razão dos avanços das técnicas de solução e modelagem numérica. Sendo assim, o objetivo desta pesquisa foi desenvolver modelos numéricos tridimensionais em elementos finitos para simular o comportamento de pilares em aço em situação de incêndio, permitindo a utilização desses modelos em análises paramétricas futuras para a determinação da resistência ao fogo de pilares. Testaram-se dois programas largamente utilizados na análise numérica de estruturas: o ANSYS e o ABAQUS. Validaram-se por comparação os resultados numéricos com experimentos publicados na literatura internacional e nacional. Consideraramse relevantes para a determinação da resistência ao fogo os seguintes parâmetros: nível de carga, rigidez da estrutura circundante, formas e dimensões da seção transversal. Os resultados apontaram que os modelos e estratégicas numéricas utilizadas mostraram-se adequados para fins de análises térmicas e termoestruturais, sendo capazes de prever o comportamento térmico e mecânico dos pilares tubulares de aço em situação de incêndio, com boa correlação com os resultados experimentais. As colunas apresentaram tempos críticos inferiores aos divulgados na literatura. O aumento da rigidez axial não influenciou de maneira significativa nos tempos críticos das análises. As forças de restrições relativas foram maiores para os menores níveis de cargas.
Currently, especially in Brazil, the performance of structures subjected to fire action has been a great concert, due to the risks inherent in this situation. For example, only in Pernambuco, in the triennium 2011-2013, the Fire Department reported the increase of 1600 fires per year in buildings (residential, commercial or industrial). Disasters associated with fire as these can result in significant financial loss; historical, cultural, environmental damage, in addition to irreparable losses of human life as occurred in the Kiss nightclub in Santa Maria - RS (2013). This work aims to analyze the performance of steel columns on fire due to the great importance of this element for the structural design and the consequent safety of the building. Several factors influence the behavior of columns in fire situation, quotes, for example, the load level at which the post is submitted, the form and dimensions of the cross section, the slenderness ratio of the column and the behavior of the mechanical properties and characteristics of materials under elevated temperatures. Because of the complexity of the parameters involved in the analysis of structures in case of fire, the fire resistance of structural elements like pillars is determined experimentally. However, in general, these tests are expensive and difficult to perform. This often negatively affects the study of a large number of samples, not allowing a better understanding of the problem. In this sense the numerical models are extremely important for the study of structures in fire, as it has been possible to play them because of advances in solving techniques and numerical modeling. Thus, the objective of this research is to develop three-dimensional numerical models in finite elements to simulate the behavior of steel columns in fire situation, allowing the use of models in future parametric analysis to determine the fire resistance of columns. Two programs widely used in numerical analysis of structures were tested: ANSYS and ABAQUS. The numerical results were validated by comparison with experiments published in the international and national literature. Relevant parameters to the determination of the fire resistance were considered: load level, stiffness of the surrounding structure, shape and dimensions of the transverse section were considered.