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20. Parametric Study on the Buckling of Unbraced Steel Frames under Fire Situation.

Author

Silva, Thiago, Couto, Carlos, Vila Real, Paulo, and Lopes, Nuno

Subjects
STEEL framing, MECHANICAL buckling, FINITE element method, COLUMNS, HIGH temperatures, STEEL analysis, STRUCTURAL design
Abstract

A parametric investigation of several unbraced steel frames with regular and irregular geometry subjected to elevated temperatures is carried out in this study to determine the most accurate procedure and buckling lengths to be considered during the structural design under a fire situation. In such conditions, the stiffness and strength of steel decrease considerably due to high temperatures, and uncertainty remains in the application of the fire design rules of Eurocode 3 Part 1-2 (EN 1993-1-2) for unbraced frames as no information is given regarding the treatment of the deformed geometry (the so-called second-order effects). More precisely, it is unclear in the norm whether the verification based on the buckling length concept could be used or if a second-order analysis to calculate the internal forces is sufficient to ensure the stability of the frame in case of fire. Based on the linear buckling analysis of the steel frames accounting for the temperature development during a fire, recommendations for the appropriate buckling lengths to be used are given. Finally, it is demonstrated that using the recommended buckling lengths together with the design rules of EN 1993-1-2 leads to results in favor of safety when compared to the results obtained with the finite element method. On the other hand, it is concluded that using second-order internal forces and the real length of the columns as the buckling length, as suggested for room temperature design, yielded results outside safety when compared with the finite element method, and this analysis and verification procedure should not be used for the case of fire. [ABSTRACT FROM AUTHOR]

Published
2024
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39. Load bearing capacity of stainless steel beams at elevated temperatures

Author

Alves, Matheus Henrique, Mesquita, L.M.M., Piloto, P.A.G., Lopes, Nuno, Arrais, Flávio, Vila Real, Paulo M.M., and Pinho-da-Cruz, Joaquim

Subjects
Stainless stee, Bending resistance, Elevated temperatures
Abstract

To analyse the load bearing capacity of stainless steel (SS) members at elevated temperatures, a set of three-point bending tests was conducted on RHS 150x100x5 beams with SS grade 1.4301. The numerical modelling of these tests has been performed at elevated temperatures, achieving close approximation to observed experimental results. The load bearing capacity difference between the numerical results and the experimental results is smaller than 10%. Analytical methods were also used to predict the load-deflection behaviour. info:eu-repo/semantics/publishedVersion

Published
2022

40. Stainless steel members strength at elevated temperatures

Author

Lopes, Nuno, Arrais, Flávio, Vila Real, Paulo M.M., Alves, Matheus Henrique, Mesquita, L.M.M., and Piloto, P.A.G.

Subjects
Aço inoxidável, Temperaturas elevadas, Resistência mecânica
Abstract

O presente artigo apresenta um estudo experimental sobre a caracterização mecânica do aço inoxidável austenítico 1.4301, à temperatura normal e a altas temperaturas. As leis constitutivas obtidas por ensaios à tração são comparadas com as preconizadas no Eurocódigo 3 (EC3), cujos respetivos modelos materiais foram recentemente sujeitos a propostas de alteração, necessitando ainda de completa validação. Por fim analisa-se a influência da aplicação das diferentes leis constitutivas na modelação numérica de vigas com secções retangulares ocas (RHS) e na respetiva resistência ao fogo. info:eu-repo/semantics/publishedVersion

Published
2022

41. Analysis of stress and strain in a rotating disk mounted on a rigid shaft

Author

Alexandrova Nelli N., Alexandrov Sergei, and Vila Real Paulo M.M.

Subjects
Rotating shaft-disk assembly, plane stress, strain distribution, Mises yield criterion, semi-analytical solution, Mechanics of engineering. Applied mechanics, TA349-359
Abstract

The plane state of stress in an elastic-perfectly plastic isotropic rotating annular disk mounted on a rigid shaft is studied. The analysis of stresses, strains and displacements within the disk of constant thickness and density is based on the Mises yield criterion and its associated flow rule. It is observed that the plastic deformation is localized in the vicinity of the inner radius of the disk, and the disk of a sufficiently large outer radius never becomes fully plastic. The semi-analytical method of stress-strain analysis developed is illustrated by some numerical examples. .

Published
2006
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45. Bending resistance of stainless steel beams at elevated temperatures

Author

Alves, Matheus Henrique, Mesquita, L.M.R., Piloto, P.A.G., Lopes, Nuno, Arrais, Flávio, and Vila Real, Paulo M.M.

Subjects
Bending resistance, Experimental tests, Stainless steel, Elevated temperatures
Abstract

Structural stainless steel elements at elevated temperatures behave differently than structural carbon steels. To analyse this behaviour, a set of three-point bending tests on 150x100 RHS, Class 1 cross-section, stainless steel grade 1.4301 beams at elevated temperatures were conducted. Numerical modelling of these tests has been afterwards performed at the measured temperatures, achieving close approximation to observed experimental results. info:eu-repo/semantics/publishedVersion

Published
2021

46. Resistência mecânica de elementos em aço inoxidável a temperaturas elevadas

Author

Lopes, Nuno, Arrais, Flávio, Vila Real, Paulo M.M., Alves, Matheus Henrique, Mesquita, L.M.R., and Piloto, P.A.G.

Subjects
Aço inoxidável, Temperaturas elevadas, Resistência mecânica
Abstract

O presente artigo apresenta um estudo experimental sobre a caracterização mecânica do aço inoxidável austenítico 1.4301, à temperatura normal e a altas temperaturas. As leis constitutivas obtidas por ensaios à tração são comparadas com as preconizadas no Eurocódigo 3 (EC3), cujos respetivos modelos materiais foram recentemente sujeitos a propostas de alteração, necessitando ainda de completa validação. Por fim analisa-se a influência da aplicação das diferentes leis constitutivas na modelação numérica de vigas com secções retangulares ocas (RHS) e na respetiva resistência ao fogo. info:eu-repo/semantics/publishedVersion

Published
2021

47. Caracterização experimental da resistência ao fogo de vigas RHS em aço inoxidável

Author

Lopes, Nuno, Arrais, Flávio, Vila Real, Paulo M.M., Alves, Matheus Henrique, Mesquita, L.M.R., Piloto, P.A.G., and Pinho-da-Cruz, Joaquim

Subjects
Comportamento mecânico, Temperaturas elevadas, Elementos estruturais em aço inoxidável
Abstract

Com o objetivo de analisar experimentalmente o comportamento mecânico de elementos estruturais em aço inoxidável a temperaturas elevadas, foi realizado um conjunto de ensaios de resistência ao fogo, à flexão em três pontos, a perfis com secção transversal RHS150x100x5, em aço inoxidável 1.4301, aplicando a curva de aquecimento padrão ISO 834. Os resultados são analisados e comparados com os obtidos por modelação numérica, realizada com o programa de elementos finitos SAFIR, validando o modelo numérico construído e a aplicação da lei constitutiva para o aço inoxidável a temperaturas elevadas proposta na nova geração da Parte 1-2 do EC3. info:eu-repo/semantics/publishedVersion

Published
2021

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