EM - Escola de Minas

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6

Notícias

A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.

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2011 - 201952020 - 20235

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Autor: search.filters.author.Amparo, Lucas RoqueteTem arquivos: Sim

Resultados da Pesquisa

Agora exibindo 1 - 10 de 10
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    Numerical and theoretical investigation of bolted sleeve connections with rectangular hollow sections.
    (2023) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Tanus, Lucas da Silva; Monteiro, Isabella Estevão; Alves, Vinicius Nicchio; Sarmanho, Arlene Maria Cunha
    This article presents a theoretical and numerical study of bolted sleeve connections with rectangular hollow sections (RHS) under axial tension and compression. The geometric form of a hollow section provides resistance for high axial loads, torsion and combines effects, spreading its utilization in truss systems. In this context, the sleeve connections proposed explore these characteristics of RHS and offer an attractive aesthetic appearance for the continuity of elements. The bolted sleeve connection with RHS is formed by two outer tubes connected by an inner tube and staggered bolts. Herein, a parametric study was developed for identification of the failure modes in the connection. Finite element models with different geometric parameters and number of bolts were created in commercial software. The width, depth and thickness of RHS tubes and diameter of bolts were variated. In the theoretical/numerical/ parametric results, the yielding gross section failure, the fracture through the effective net area failure and the bearing failure were observed. These failure modes occurred in both outer and inner tubes. The load results were compared to determine the resistance capacity of sleeve connections. The theoretical formulations were evaluated for representation of the ultimate load of the failure modes.
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    Design of sleeve connections with cross-bolted on circular hollow sections under axial tension.
    (2022) Amparo, Lucas Roquete; Oliveira, Matheus Miranda de; Sarmanho, Arlene Maria Cunha; Xavier, Ellen Martins; Alves, Vinicius Nicchio
    This present paper evaluates the behavior and resistance capacity of cross-bolted sleeve connections with circular hollow sections (CHS) under axial tension. This connection allows harmony in the continuity of the tubes. The cross-bolted sleeve connection with CHS comprises outer tubes connected by an inner tube and cross bolts at 90◦. Therefore, an experimental, numerical, and parametric study was conducted to identify the connection’s possible failure modes. The experimental tests were developed with cross bolts at 90◦, which enable the identification of fracture through the effective net area, bearing failure, and bolt bending. Finite element (FE) numerical models were developed and validated by Ansys software to provide a parametric study. Thus, such a parametric study was carried out using the verified FE models. The failure modes were evaluated considering the effects of geometric properties concerning their type and location; a relative slenderness limit for the design of connections was proposed, directing the occurrence of a failure in the outer tube. Normative prescriptions do not foresee the design of the sleeve. Therefore, new formulation methods for estimating the strength were proposed, allowing the design of these connections.
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    Bearing failure in bolted sleeve connections with circular hollow sections under compression.
    (2020) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Alves, Vinicius Nicchio
    This article analyzes sleeve connections between circular hollow sections. This type of connection is composed of two tubes connected by bolts to an inner tube with a smaller diameter, and explores the efficiency, aesthetics and resistance of hollow sections subjected to tension and compression. In previous researches, sleeve connec- tions with aligned and crossed bolt dispositions and under axial tension were studied. Herein, the behavior of sleeve connections with aligned bolts and under compression was analyzed. A model to represent the connection using the finite element method was developed, which allowed a numerical analysis with geometric property varia- tions. In the numerical/parametric results, bearing failure was observed in all cases, either in the outer or inner tube. Limiting the number of bolts to 6 and considering that connections have a lower outer thickness than the inner tube, a formulation was proposed to determine the ultimate bearing capacity of sleeve connections under com- pression and with bearing failure.
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    Behavior and design formulation of steel CHS with sleeve connections.
    (2021) Amparo, Lucas Roquete; Oliveira, Matheus Miranda de; Sarmanho, Arlene Maria Cunha; Xavier, Ellen Martins; Alves, Vinicius Nicchio
    Structures with tubular profiles gain space in civil construction due to their excellent response under tension, compression, and torsion. They are widely used in structural trusses, especially in large lengths. The profiles have a limited size due to the manufacturing and transport process. Therefore, there is a need to use some mechanism to perform the joint of profiles and obtain the desired length. This work aims to develop a new type of bar splice in circular hollow section (CHS) connection called sleeve connection, composed of two tubes connected with another smaller diameter tube with bolts arranged in a line (staggered bolts). This research presents an experimental, numerical, and parametric study of sleeve connection in CHS under centric axial tension. A numerical model was developed using the finite element method (FEM) considering sleeve connection with staggered bolts. From the numerical results, it was possible to analyze the connection behavior and failure modes: yielding gross cross-section, fracture through the effective net area, bolt shear failure, bearing failure of the plate, and bolt bending failure. This way, formulations were proposed to predict the sleeve connections' behavior with staggered bolts as a function of the failure modes.
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    Bearing failure in bolted sleeve connections with circular hollow sections under compression.
    (2020) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Alves, Vinicius Nicchio
    This article analyzes sleeve connections between circular hollow sections. This type of connection is composed of two tubes connected by bolts to an inner tube with a smaller diameter, and explores the efficiency, aesthetics and resistance of hollow sections subjected to tension and compression. In previous researches, sleeve connections with aligned and crossed bolt dispositions and under axial tension were studied. Herein, the behavior of sleeve connections with aligned bolts and under compression was analyzed. A model to represent the connection using the finite element method was developed, which allowed a numerical analysis with geometric property variations. In the numerical/parametric results, bearing failure was observed in all cases, either in the outer or inner tube. Limiting the number of bolts to 6 and considering that connections have a lower outer thickness than the inner tube, a formulation was proposed to determine the ultimate bearing capacity of sleeve connections under compression and with bearing failure.
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    Estudo de ligações tipo luva em perfis tubulares.
    (2018) Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha; Sarmanho, Arlene Maria Cunha; Carvalho, Hermes; Carvalho, Eliane Maria Lopes; Mazon, Ana Amélia Oliveira; Alves, Vinicius Nicchio
    O uso de estruturas com perfis tubulares tem ganhado espaço na construção civil principalmente devido ao desempenho estrutural associado a resistência as forças axiais e alta rigidez torcional. O processo de fabricação e transporte de estruturas metálicas condiciona o comprimento dos perfis a valores máximos que em muitos casos não correspondem ao vão da edificação. Assim, tem-se a necessidade de utilização de algum mecanismo que possibilite a emenda dos perfis/elementos, e então obter o comprimento desejado. Nesta pesquisa apresenta-se um estudo teórico, numérico e experimental de uma nova tipologia de ligação de emenda de perfis tubulares, denominda por ligação luva. Sua composição é formada por perfis tubulares estruturais de aço, com seção transversal circular. A ligação dos tubos é feita utilizando-se um tubo adicional de menor diâmetro posicionado internamente aos tubos, e conectados por meio de parafusos passantes. Os parafusos podem estar posicionados de forma alinhada (em eixo) ou cruzada (em eixo cruzados). No programa experimental foram avaliados 43 protótipos da ligação luva com parafusos alinhados e com parafusos cruzados. A avaliação dos resultados experimentais contribuiu para o entendimento do comportamento da ligação luva e permitiu o desenvolvimento e calibração dos modelos numéricos. Com uso de um programa computacional, em elementos finitos, Ansys, foi desenvolvido um modelo numérico calibrado com os resultados experimentais, sendo esse a base para o estudo paramétrico. Na análise numérica paramétrica foram simulados e analisados um total de 374 modelos numéricos, considerando a ligação luva com parafusos alinhados e com parafusos cruzados. Dessa forma, a partir dos resultados numéricos, foi possível identificar e analisar adequadamente os possíveis modos de falhas da ligação: escoamento da seção bruta, ruptura da seção líquida, cisalhamento dos parafusos, ovalização dos furos e flexão dos parafusos, bem como limites geométricos de utilização da luva. Em seguida foram propostas formulações para os modos de falha da ligação com parafusos alinhados e cruzados e os bons resultados, demonstram a viabilidade da utilização dessa nova tipologia de ligação.
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    Experimental analysis of bolts employed as shear connectors in circular concrete-filled tube columns.
    (2019) Xavier, Ellen Martins; Ribeiro Neto, Juliano Geraldo; Sarmanho, Arlene Maria Cunha; Amparo, Lucas Roquete; Paula, Letícia Gualberto Caldeira de
    This paper presents experimental and theoretical analysis of bolts employed as shear connectors in circular concrete-filled steel tube columns (CFTs). The theoretical results, obtained from ABNT NBR 16239:2013 formulations, were compared with the experimental results. A series of push-out tests were carried out, where the diameter and length of the bolts, the number of connectors and the concrete strength were varied. From the experimental results, it was observed that the equations from ABNT NBR 16239:2013 are conservative. Therefore, it is proposed an adjustment to the formulations in order to consider the concrete confinement. It was also verified that increments in the diameter and the length of the bolt increase the load capacity of the connector. However, the variation of the quantity of bolts and the concrete strength did not interfere in the load capacity.
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    Numerical analysis of truss systems with stiffened flattened end-bars.
    (2018) Mazon, Ana Amélia Oliveira; Sarmanho, Arlene Maria Cunha; Nunes, Gabriel Vieira; Amparo, Lucas Roquete; Neiva, Luiz Henrique de Almeida; Souza, Flávio Teixeira de
    Circular hollow sections are usually used in long-span roof truss systems. One of the typology for connecting elements in such structures involves the flattening of bar ends. This article presents the numerical analysis of a plane truss composed of circular hollow sections, in which diagonal bars have flattened ends. In this sense, a new flattening typology called stiffened flattening is proposed, characterized by a non-flat geometry, with the creation of stiffeners in the lateral edges of the diagonal flattened ends. The diagonal connecting system with the chord members uses connecting plates. The plates are welded to the chords and the diagonals are connected to latter through a single bolt. The numerical analysis using finite elements method was developed in two stages through ANSYS software with the Parametric Design Language (APDL), in which parameters such as geometry, materials, element types, boundary conditions and loads are specified. A non-linear analysis was performed using shell elements on the chords, diagonals, plates and welds, and contact elements between the diagonals with stiffened flattened ends and the connecting plates. Initially, a numerical study of the connecting node and the stiffened flattened end was performed, and the results directed the modeling of the plane truss. The numerical results were calibrated with the experimental truss results in full scale. The numerical result of the plane truss was also compared to a theoretical study, considering the axial load eccentricity applied in the diagonal with stiffened flattened ends. The study was based on the consideration of combined effects of axial force and bending moment provided by the Brazilian standard ABNT NBR 8800:2008. The final results indicate that the numerical model proposed is efficient and has good correlation with the experimental and theoretical results.
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    Influência da inércia térmica do solo e da ventilação natural no desempenho térmico : um estudo de caso de um projeto residencial em light steel framing.
    (2011) Souza, Henor Artur de; Amparo, Lucas Roquete; Gomes, Adriano Pinto
    The light steel framing technology requires some design adaptations in order to have an adequte thermal performance in Brazil, since it was imported from the USA, In this study, the thermal performance of a light steel frame single-family house, in Belo Horizonte, state of Minas Gerais, was evaluated considering some natural ventilation strategies and the influence of soil inertia. To determine the model’s thermal behaviour, the EnergyPlus simulation program was used. The following stages were carried out: characterization of the structure, its typical exposure to the weather; occupants’ profile and their demands; configuration of closing system; and the evaluation of the building’s thermal comfort conditions and to what extent they meet existing standards. The conclusion was made that a suitably ventilation system could significantly improve the building’s thermal performance, if the local climatic conditions are duly taken into account. Likewise, depending on the land plot topography and the design characteristics, the influence of the soil thermal inertia, when associated to suitable ventilation and shading strategies, could be helpful to improve the design thermal performance.
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    Análise teórico-experimental de ligações tipo luva compostas por perfis tubulares com parafusos em linha e cruzados.
    (2014) Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha
    Os perfis tubulares de aço possuem ótimo desempenho estrutural aos esforços de tração, compressão e torção, bem como à combinação dos mesmos. Assim, novas pesquisas tem se intensificado para avaliar o comportamento e a resistência dos elementos desses perfis. Dentre as diversas utilizações de perfis tubulares pode-se citar os sistemas treliçados de coberturas. Nesses sistemas um fator importante é o processo de padronização associado a rapidez de montagem. Este trabalho apresenta um estudo teórico e experimental de uma nova tipologia de ligação denominada luva, desenvolvida para atender aos princípios de facilidade de montagem. A ligação é composta por dois tubos ligados internamente por meio de um terceiro tubo de diâmetro menor com parafusos passantes dispostos em linha e cruzados. Essa ligação facilita a montagem da estrutura como um todo sendo esteticamente mais vantajosa quando comparada com a ligação flangeada, mais usual em perfis tubulares. Foi realizado um programa experimental de ligação luva com parafusos dispostos em linha (longitudinal ao tubo) e cruzados a 90°. Foram realizados 3 ensaios com protótipos com parafusos em linha complementares a resultados obtidos em pesquisa anterior e 12 ensaios para ligação com parafusos cruzados. Os parâmetros considerados para investigação foram: diâmetro e espessura dos tubos e o número de parafusos. Com os resultados experimentais identificou-se o mecanismo de colapso e capacidade resistente da ligação. Pela análise dos dados experimentais e teóricos observou-se que o modo de falha dominante foi o de flexão do parafuso e ainda que há necessidade de determinação de um coeficiente de redução da resistência final da ligação. Com as análises foi proposta uma expressão para a determinação da falha por flexão dos parafusos apresentando-se um novo procedimento para a determinação da capacidade resistente da ligação tipo luva. Os bons resultados obtidos demonstraram a viabilidade da utilização dessa nova tipologia de ligação, desde que observados os mecanismos de falha possíveis.