EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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10 resultados
Resultados da Pesquisa
Item Effect of chord length on CHS-RHS T-joints with slender sections.(2021) Pereira, Daniel José Rocha; Guerra, Messias Júnio Lopes; Sarmanho, Arlene Maria Cunha; Silva Neto, João Batista da; Nunes, Gabriel Vieira; Alves, Vinicius NicchioThe chord length is an essential geometric property that must be defined in the analysis of isolated joints composed of hollow steel sections, as well as the boundary conditions of the test. The analysis of these parameters’ effect on the behavior of joints has been addressed by other studies, mostly with joints between circular hollow sec- tions with compact or semi-compact cross-sections. Recent research about tubular joints has addressed cases with slender sections, where the design of joints containing these sections is still in development. In this context, this study aimed to evaluate the effect of the chord length in the behavior of T-joints between circular hollow section braces and slender rectangular hollow section chords through experimental tests and a numerical study considering the application of axial compression at the braces. The joint behavior was examined through the load-strain and load-deformation curves and the von Mises stress distribution, which allowed the failure mode's determination and the joint resistance value. Chord face failure was observed in the prototypes. It was concluded that a minimum chord length of 0.6m would be the adequate value for the study of the T-joints containing the geometric properties used in this study, which would be equivalent to a chord length five times higher than the width of the cross- section (5b0).Item Experimental and numerical assessment of CHS-RHS T-joints with chords subjected to axial tensile forces.(2021) Silva Neto, João Batista da; Nunes, Gabriel Vieira; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Guerra, Messias Júnio Lopes; Alves, Vinicius NicchioHollow steel sections are widely used in the construction industry due to their mechanical properties. Joints used in these structures are the subject of research because of their singular and critical behavior. Joints containing chords with more slender cross-sections and axially loaded are still a challenge for design, especially in joints with circular hollow sections (CHS) in the braces and rectangular hollow sections (RHS) in the chords. In this context, this work aimed to study joints formed by a combination of CHS braces subjected to compression loads and RHS chords axially loaded with tension, welded as T-joints. Experimental tests, a numerical model using finite elements, and a parametric analysis were developed. A new equation for the chord stress function was proposed, including joints containing chords with semi-compact sections in tension. The joint resistance values obtained through the numerical models were compared with the equations from ISO 14346:2013 and with the proposed equation. It was observed that, for the numerical models with geometric properties inside the normative validity ranges of ISO 14346:2013, the mean rate of analytical by numerical joint resistance results was equal to 68%, using either the normative or the proposed equation. In the same way, for models outside the current validity ranges, either the proposed equation or the modified equation from ISO 14346:2013 could be used to design CHS-RHS T-joints with the geometric and material properties analyzed.Item Structural behaviour of thin-walled CHS-RHS T-joints : experimental and numerical assessment.(2021) Guerra, Messias Júnio Lopes; Pereira, Daniel José Rocha; Silva Neto, João Batista da; Nunes, Gabriel Vieira; Sarmanho, Arlene Maria Cunha; Lima, Luciano Rodrigues Ornelas deThe design of tubular joints with slender cross-sections is currently limited by the validity ranges of established international design standards. Aiming to assess the structural behaviour of tubular joints characterised by thinwalled chord cross-sections, this paper initially reports, an experimental investigation into tubular T-joints consisted of CHS braces welded to thin-walled cold-formed RHS chords, which slenderness values were outside of the current design standard limits. The experimental programme was carried out on 12 cold-formed steel slender cross-section prototypes where the braces were subjected to axial compressive loading. The geometric parameters, including chord and brace thickness and brace diameter were varied. The connected chord face failure was the failure mode observed in all tests. The results of the experimental tests were thoroughly discussed. A second step was used to calibrate a numerical model that was the basis for a parametric analysis involving the most relevant parameters affecting the joint’s behaviour. The obtained joint’s strengths were compared with those forecasted by ISO 14346 developed for compact cross-sections modifying the chord stress function concerning the elastic cross-section modulus and effective cross-section area when slender cross-section chords are concerned. However, this approach leads to scattered predictions, roughly too conservative. Finally, this paper proposes an alternative design approach for the studied joints that are more accurate in predicting their strength when compared to the presented experimental and numerical results.Item Análise numérica de ligações tipo T com perfis tubulares.(2019) Guerra, Messias Júnio Lopes; Nunes, Gabriel Vieira; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Neiva, Luiz Henrique de AlmeidaNeste trabalho é apresentada uma análise paramétrica de ligações soldadas do tipo T formadas por perfis estruturais de aço sem costura, com seção transversal retangular no banzo e circular no montante. Um modelo numérico foi calibrado com resultados experimentais e após a calibração foi feito um estudo paramétrico variando os parâmetros (relação entre o diâmetro do montante e largura da face banzo conectado) e 2 (relação entre a largura e a espessura da face do banzo). Os resultados dos modelos numéricos, obtidos pelo critério de deformação limite, foram comparados com as prescrições mais recentes da ABNT NBR 16239 (2013) e da ISO 14346 (2013).Item Effect of fillet welds on T-joints with thin-walled chords.(2018) Pereira, Daniel José Rocha; Sarmanho, Arlene Maria Cunha; Nunes, Gabriel Vieira; Guerra, Messias Júnio Lopes; Alves, Vinicius NicchioTubular joints with thin-walled sections could have a wide range of applications in the construction industry, possibly providing light structures with high structural efficiency. However, current design prescriptions do not recommend their use and more studies are needed to attest their viability. In this context, the effect of the size of fillet welds on cold-formed T-joints consisting of thin-walled rectangular hollow section chords and circular hollow section braces under axial compression loading was analysed. Experimental and numerical analyses were conducted and the results were compared with current design prescriptions. Three experiments were performed, with different weld sizes, in a machine that provided displacement-controlled testing with data acquisition from strain gauges and displacement transducers. Finite-element models were developed to replicate the general experimental setup and the results showed good correlation with the experimental data, indicating that the size of the weld influences joint resistance.Item Cold formed steel semi rigid joints.(2018) Silva, Adriano Toledo da; Sarmanho, Arlene Maria Cunha; Nunes, Gabriel Vieira; Pereira, Daniel José Rocha; Neiva, Luiz Henrique de AlmeidaThis article presents a theoretical and numerical study of an innovative joint using cold-formed steel sections. The motivation for the study of this connection is the ease of manufacturing and assembly that it provides. The profiles are made of coldformed lipped channel sections, which are welded to form closed built-up sections on the columns and open built-up lipped sections to the beams. The beams use endplates connected by bolts (threaded bars) to the columns. The study evaluates the connection’s initial stiffness of 19 models, where the following parameters were varied: the thickness of the profiles and endplates, the height of the column sections and the diameter of the bolts. A theoretical and a numerical study were developed: the numerical study was performed using finite elements through the commercial software ANSYS, whereas the theoretical study was made based on the component method, prescribed by Eurocode 3, that does not include the design of the connection analyzed herein. Thus, aiming to enable the design of joints composed of cold-formed lipped channel sections, the analysis results were compared and an adjustment coefficient, proportional to the slenderness of the column’s plates, was proposed. The coefficient was introduced to the stiffness component that represents the column web in compression in the mechanical model. The ratio between the coefficients’ numerical and theoretical values presented a maximum variation of 11%, which was considered satisfactory.Item 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 deCircular 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.Item Análise teórica-experimental de ligações com perfis metálicos tubulares (retangulares e circulares) considerando o efeito do carregamento do banzo.(2017) Nunes, Gabriel Vieira; Sarmanho, Arlene Maria Cunha; Sarmanho, Arlene Maria Cunha; Gesualdo, Francisco Antônio Romero; Lima, Luciano Rodrigues Ornelas de; Mazon, Ana Amélia; Martins, Joel DonizeteEste trabalho apresenta um estudo experimental, teórico e numérico de ligações tubulares de sistemas treliçados do tipo “T” compostas por perfis tubulares retangulares no banzo e perfis tubulares circulares no montante. As análises foram realizadas considerando carregamento axial de compressão no montante e de tração ou compressão no banzo. Com o carregamento no banzo foi possível avaliar sua influência na capacidade resistente da ligação. Foram realizados 23 ensaios sendo divididos em três séries distintas segundo os parâmetros geométricos e 2. As séries contemplam ensaios com sete níveis diferentes de carregamento, sendo três níveis de carregamento de compressão, três de tração e sem carregamento no banzo. Os resultados experimentais indicaram a eficiência do aparato de ensaio desenvolvido e o modo de falha de plastificação no banzo (Modo A). O deslocamento relativo da face do banzo foi medido experimentalmente e seus valores utilizados para determinação da força resistente da ligação segundo o critério de deformação limite. Foi desenvolvido modelo numérico em elementos finitos utilizando o programa Ansys. O elemento utilizado foi de casca e os resultados foram comparados com os resultados experimentais. O modelo numérico foi calibrado com os testes experimentais para cada protótipo e diferentes condições de carregamento. Os resultados indicam uma boa correlação que permite o seu uso para determinar a resistência das ligações. Os resultados numéricos e experimentais foram comparados às prescrições da NBR 16239: 2013 e ISO 14346: 2013. Os resultados indicaram boa correlação quando não há carregamento no banzo. Por outro lado, com força de compressão ou tração, não houve boa correlação. Observou-se uma redução na resistência das ligações associada à compressão axial no banzo. No entanto, um aumento na resistência das ligações foi verificado para os testes em que carregamento de tração foi aplicado no banzo. Foram propostas novas equações para compressão e tração no banzo. Os resultados obtidos mostraram boa correlação das equações propostas quando comparadas com resultados experimentais e numéricos.Item Análise numérica de ligações tipo “T” com perfis tubulares de paredes esbeltas.(2017) Guerra, Messias Júnio Lopes; Sarmanho, Arlene Maria Cunha; Nunes, Gabriel Vieira; Pereira, Daniel José Rocha; Silva Neto, João Batista daNeste trabalho é apresentada uma análise teórica e numérica de ligações soldadas do tipo “T” formadas por perfis tubulares de aço de seções esbeltas, com seção transversal retangular no banzo e circular no montante. Os estudos avaliam o comportamento, os modos de falha e a carga última da ligação. Foi analisada a influência dos parâmetros 2 (razão entre a largura e a espessura do banzo) e (razão entre o diâmetro do montante e a largura banzo). Os modelos numéricos em elementos finitos e os resultados foram comparados com as prescrições normativas recentes, utilizando o critério de deformação limite para determinação da carga última para o modo de falha de plastificação da parede superior do banzo.Item Análise numérica paramétrica de ligações tipo “T”, “K” e “KT” compostas por perfis tubulares de seção retangular e circular.(Programa de Pós Graduação em Engenharia Civil. Departamento de Engenharia Civil, Escola de Minas, Universidade Federal de Ouro Preto., 2012) Nunes, Gabriel Vieira; Sarmanho, Arlene Maria CunhaNeste trabalho é apresentado um estudo numérico de ligações soldadas do tipo “T”, “K” com afastamento e “KT” com afastamento, formadas por perfis tubulares estruturais de aço sem costura, com seção transversal retangular no banzo e circular no montante e nas diagonais. Foram desenvolvidos modelos numéricos sendo realizado um estudo de refinamento de malha e de condições de contorno visando a definição do modelo mais eficiente para as análises. Os modelos numéricos foram calibrados com resultados experimentais obtidos em estudos anteriores realizados no Laboratório de Estruturas “Prof. Altamiro Tibiriçá Dias” do Departamento de Engenharia Civil da Escola de Minas da Universidade Federal de Ouro Preto. Após a calibração foi feito um estudo paramétrico variando os parâmetros (relação entre o diâmetro do montante/diagonal e largura da face banzo conectado), 2 (relação entre a largura e a espessura da face do banzo). Também foi realizado um estudo da influência de carregamento no banzo. Os resultados dos modelos numéricos, obtidos pelo método da deformação limite, foram comparados com as prescrições mais recentes do CIDECT (Comité international pour le développement et l'etude de la construction tubulaire) e com o projeto da norma brasileira de tubos (PN:2011). No estudo numérico foi feito uma avaliação de refinamento de malha que possibilitou gerar modelos com número adequado de elementos e baixo custo computacional, e também foi avaliada a influência das condições de contorno nos resultados do modelo. Na calibração, os modelos numéricos tiveram uma ótima correlação quando comparados com os modelos experimentais, validando o estudo paramétrico das ligações. O modo de falha dominante para todos os modelos foi a plastificação da face superior do banzo. No geral houve boa correlação e mesmo comportamento dos modelos numéricos e as prescrições das normas estudadas tanto no estudo sem carga no banzo quanto no estudo com carga no banzo.