Lateral Torsional-Buckling of Class 4 Steel Plate Beams at Elevated Temperature: Experimental and Numerical Comparison

2015 ◽  
Vol 6 (3) ◽  
pp. 223-236 ◽  
Author(s):  
Martin Prachar ◽  
Michal Jandera ◽  
Frantisek Wald ◽  
Bin Zhao
Keyword(s):  
Elevated Temperature ◽  
Cross Sections ◽  
Elevated Temperatures ◽  
Numerical Comparison ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Ongoing Research ◽  
Steel Members ◽  
Set Up ◽  
Hot Rolled

This paper presents ongoing research in behaviour of laterally unrestrained beams (I or H section) of Class 4 cross-sections at elevated temperatures, which is based on the RFCS project FIDESC4 - Fire Design of Steel Members with Welded or Hot-rolled Class 4 Cross-sections. Despite the current EC3 contains a number of simple rules for design of slender Class 4 cross-sections at elevated temperature, based on recent numerical simulations they were found to be over-conservative. Therefore, new well representing design models, which simulate the actual behaviour of the structures exposed to fire, are crucial. These design rules should be based on extensive numerical simulation validated on experimental data. Within this task, several tests were carried out to study lateral torsional buckling of Class 4 beams in fire. The design of the test set-up and description of the experiment is given, as well as verification of numerical model.

scholarly journals PARAMETRIC STUDY ON THE LATERAL TORSIONAL BUCKLING OF STAINLESS STEEL I BEAMS WITH CLASS 4 CROSS-SECTIONS IN CASE OF FIRE

2016 ◽  
Author(s):  
Nuno Lopes ◽  
Pedro Gamelas ◽  
Paulo Vila Real
Keyword(s):  
Stainless Steel ◽  
Cross Sections ◽  
Elevated Temperatures ◽  
Numerical Study ◽  
Design Guidelines ◽  
Steel Grade ◽  
Steel Beams ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Steel Members

For predicting the behaviour of beams with thin-walled I sections, named Class 4 in Eurocode 3 (EC3), it is necessary to account for the occurrence of both local and lateral torsional buckling (LTB). These instability phenomena, which are intensified at elevated temperatures, should be accurately considered in design rules. The fire design guidelines for stainless steel members, given in Part 1-2 of EC3, propose the use of the same formulae developed for carbon steel (CS) elements. However, these two materials have different constitutive laws, leading to believe that the use of those formulae should be validated. This work presents a parametric numerical study on the behaviour of stainless steel beams with Class 4 I sections at elevated temperatures. The influences of several parameters such as stainless steel grade, loading type and cross section slenderness are evaluated, and comparisons between the obtained numerical results and EC3 rules are presented.

Fire behaviour and resistance of cold-formed steel beams with sigma cross-sections

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Flávio Arrais ◽  
Nuno Lopes ◽  
Paulo Vila Real
Keyword(s):  
Numerical Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Numerical Results ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Content Type ◽  
Finite Element Software

PurposeSigma cross-section profiles are often chosen for their lightness and ability to support large spans, offering a favourable bending resistance. However, they are more susceptible to local, distortional and lateral-torsional buckling, as possible failure modes when compared to common I-sections and hollow cross-sections. However, the instability phenomena associated to these members are not completely understood in fire situation. Therefore, the purpose of this study is to analyse the behaviour of beams composed of cold-formed sigma sections at elevated temperatures.Design/methodology/approachThis study presents a numerical analysis, using advanced methods by applying the finite element software SAFIR. A numerical analysis of the behaviour of simply supported cold-formed sigma beams in the case of fire is presented considering different cross-section slenderness values, elevated temperatures, steel grades and bending moment diagrams. Comparisons are made between the obtained numerically ultimate bending capacities and the design bending resistances from Eurocode 3 Part 1–2 rules and its respective French National Annex (FN Annex).FindingsThe current design expressions revealed to be over conservative when compared with the obtained numerical results. It was possible to observe that the FN Annex is less conservative than the general prescriptions, the first having a better agreement with the numerical results.Originality/valueFollowing the previous comparisons, new fire design formulae are analysed. This new methodology, which introduces minimum changes in the existing formulae, provides at the same time safety and accuracy when compared to the numerical results, considering the occurrence of local, distortional and lateral-torsional buckling phenomena in these members at elevated temperatures.

Fire buckling curves for torsionally sensitive steel members subjected to axial compression

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Luca Possidente ◽  
Nicola Tondini ◽  
Jean-Marc Battini
Keyword(s):  
Elevated Temperature ◽  
Practical Interest ◽  
Statistical Investigation ◽  
Truss Structures ◽  
Design Standards ◽  
Torsional Buckling ◽  
Content Type ◽  
Steel Members ◽  
Class 1 ◽  
Flexural Torsional Buckling

PurposeBuckling should be carefully considered in steel assemblies with members subjected to compressive stresses, such as bracing systems and truss structures, in which angles and built-up steel sections are widely employed. These type of steel members are affected by torsional and flexural-torsional buckling, but the European (EN 1993-1-2) and the American (AISC 360-16) design norms do not explicitly treat these phenomena in fire situation. In this work, improved buckling curves based on the EN 1993-1-2 were extended by exploiting a previous work of the authors. Moreover, new buckling curves of AISC 360-16 were proposed.Design/methodology/approachThe buckling curves provided in the norms and the proposed ones were compared with the results of numerical investigation. Compressed angles, tee and cruciform steel members at elevated temperature were studied. More than 41,000 GMNIA analyses were performed on profiles with different lengths with sections of class 1 to 3, and they were subjected to five uniform temperature distributions (400–800 C) and with three steel grades (S235, S275, S355).FindingsIt was observed that the actual buckling curves provide unconservative or overconservative predictions for various range of slenderness of practical interest. The proposed curves allow for safer and more accurate predictions, as confirmed by statistical investigation.Originality/valueThis paper provides new design buckling curves for torsional and flexural-torsional buckling at elevated temperature since there is a lack of studies in the field and the design standards do not appropriately consider these phenomena.

scholarly journals The effect of residual stresses in the lateral-torsional buckling of steel I-beams at elevated temperature

2004 ◽  
Vol 60 (3-5) ◽  
pp. 783-793 ◽  
Author(s):  
P.M.M. Vila Real ◽  
R. Cazeli ◽  
L. Simões da Silva ◽  
A. Santiago ◽  
P. Piloto
Keyword(s):  
Elevated Temperature ◽  
Residual Stresses ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling

Lateral Torsional Buckling of Split Aluminium Mullion

2016 ◽  
Vol 710 ◽  
pp. 445-450 ◽  
Author(s):  
Davor Skejić ◽  
Mladen Lukić ◽  
Nebojša Buljan ◽  
Hrvoje Vido
Keyword(s):  
Structural Material ◽  
Cross Sections ◽  
Analytical Methods ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Curtain Wall ◽  
Conservative Method ◽  
Critical Moment ◽  
Fem Modelling ◽  
Complex Process

Curtain wall industry is the major user of aluminium as a structural material in buildings, with two basic curtain wall systems: stick and unitised. The latter is preassembled in shops, with the main feature that frame profiles are split in two interlocking halves. Such cross sections are complex, open and prone to lateral torsional buckling. General formulas for the calculation of elastic critical moment for lateral-torsional buckling are provided in the EN 1999-1-1, with a long and complicated procedure for non-symmetrical sections which makes it pretty impractical for everyday use. The problem of such sections can also be assessed by FEM modelling, which is a time consuming and complex process. Curtain wall industry is in a need of a swift, if approximate and conservative, method for checking the risk of lateral torsional buckling of profiles with non-symmetrical cross sections. Some available analytical methods are applied on a practical example and their results compared to those obtained using FEM modelling.

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