scholarly journals GEM – A SOFTWARE FOR STABILITY VERIFICATION OF NON-UNIFORM MEMBERS, Adaptation of the general method procedure to fire design

2016 ◽  
Author(s):  
João Ferreira ◽  
Paulo Vila Real ◽  
Carlos Couto ◽  
Paulo Cachim
Keyword(s):  
Computer Program ◽  
Elevated Temperatures ◽  
Numerical Results ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Tapered Beam ◽  
Eurocode 3 ◽  
The Stability ◽  
Fire Design ◽  
General Method

<span lang="EN-GB">There is currently no specific rules in Part 1-2 of Eurocode 3 for the stability verification of non-uniform members under fire conditions. For normal temperature, Part 1-1 of the same code provides a General Method to check the stability against lateral and lateral-torsional buckling for these type of members, though it requires some extensive calculations. It is here demonstrated in this paper how both problems can be addressed, by exposing a procedure that accounts for the modifications of the method at elevated temperatures, and by showing its implementation within a computer program. It is also shown how the program can be used to assess the study of the method itself, by applying it to a case of a web-tapered beam-column and comparing it to numerical results.</span>

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.

scholarly journals STRAIN-STRESS EXPERIMENTAL BEHAVIOUR OF TAPERED COLUMNS IN SINGLE-SPAN FRAMES/TRAPECINIŲ KOLONŲ VIENANAVIUOSE RĖMUOSE DEFORMACIJŲ-ĮTEMPIŲ BŪVIS

2000 ◽  
Vol 6 (2) ◽  
pp. 82-86 ◽  
Author(s):  
Vaidotas Šapalas
Keyword(s):  
Local Buckling ◽  
Longitudinal Axis ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Perpendicular Plane ◽  
Strain Stress ◽  
Tapered Columns ◽  
The Stability ◽  
Experimental Behaviour ◽  
Tapered Column

Two single-span frame tests were carried out. The width of frame is 6m, column's height 4.17m. Frame supports are pinned. Connection between column and beam is rigid. Beam of the frame was loaded with two vertical and one horizontal loads. The stability of tappered columns was analysed in frame plane and in perpendicular plane, according to [1] and [2] methods. All deflections were calculated taking into account support movements. During the first frame test R1-1 the tapered column collapsed at the load 2V=400kN and H=200 kN (vertical and horizontal loads). During the second test R1-2 the tapered column collapsed at the load 2V=390 kN and H=175 kN. In both tests columns collapsed in lateral-torsional buckling way. Because the column's web is very thin at the load 2V=300 kN and H=150 kN the column's web achieved local buckling. But the column was still carrying the load. During both tests at the load 2V=300 kN and H=150 kN the column began to twist in the middle of its height about the longitudinal axis and to bend about the weak axis. In test R1-1, the vertical experimental deflection (in point 6, see Fig 1 a) is about 17.5% smaller than the theoretical one. The horizontal experimental deflection (in point, see Fig 1 a) is about 11.6% smaller than the theoretical one. In test R1-2, vertical experimental deflection (in point 6, see Fig 1 a) is about 21.1% bigger than the theoretical one. The horizontal experimental deflection (in point, see Fig 1 a) is about 29.6% smaller than the theoretical one. In test R1-1, an experimental compression stresses in section A-A (see Fig 2) are about 11.2% smaller than the theoretical one. Experimental tension stresses in section A-A are about 8.65% smaller than the theoretical one. In test R1-2, an experimental compression stresses in section A-A is about 0.43% bigger than the theoretical one. An experimental tension strain in section A-A is about 1.73% smaller than the theoretical one.

Numerical Investigation of Stainless Steel Welded I-Sections Subjected to Lateral-Torsional Buckling

2016 ◽  
Vol 853 ◽  
pp. 317-321
Author(s):  
Mohammad Anwar-Us-Saadat ◽  
Mahmud Ashraf ◽  
Shameem Ahmed
Keyword(s):  
Stainless Steel ◽  
Rational Design ◽  
Slenderness Ratio ◽  
Numerical Results ◽  
Maintenance Cost ◽  
Test Results ◽  
Structural Members ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional

Stainless steel is now widely used in construction as structural members in recognition to its unique beneficial properties such as corrosion resistance, higher strength and ductility, andnegligible maintenance cost. Recent research on stainless steel has seen development of rational design rules to predict cross-sectional resistances but still lacks in appropriate knowledge at the member level. The current paper investigates the lateral-torsional buckling (LTB) behaviour of welded stainless steel I sections. Available test results were used to develop and validate nonlinear finite element (FE) models. Limited experimental evidences were supplemented by a large number of reliable numerical results covering wider range of member slenderness ratio. All test and numerical results were used to investigate the performance of Eurocode EN-1993-1-4 and Australian code AS/NZS 4673 in predicting member resistances against lateral-torsional buckling.

SIMPLE FIRE DESIGN OF COLD-FORMED STEEL C-SECTION BEAMS WITH LATERAL-TORSIONAL BUCKLING

ce/papers ◽  
2017 ◽  
Vol 1 (4) ◽  
pp. 573-590
Author(s):  
Luís Laím ◽  
João Paulo C. Rodrigues
Keyword(s):  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cold Formed Steel ◽  
Fire Design

Lateral-Torsional Buckling of Nonuniformly Loaded Beam Using Differential Transformation Method

2016 ◽  
Vol 16 (07) ◽  
pp. 1550034 ◽  
Author(s):  
Ryszard Hołubowski ◽  
Kamila Jarczewska
Keyword(s):  
Critical Loads ◽  
Transformation Method ◽  
Variable Coefficients ◽  
Differential Transformation Method ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Differential Transformation ◽  
Distributed Load ◽  
The Difference ◽  
The Stability

The paper presents the application of the differential transformation method (DTM) to the stability analysis of nonuniformly loaded beams under bending. The main advantage of the method is the possibility to obtain the semi-analytical solution for the critical loads of the beam undergoing lateral-torsional buckling. To determine the critical load, the system of two coupled ordinary differential equations with variable coefficients and parameters have to be solved. Numerical analyses were carried out for three different types of load functions: (i) Uniformly distributed load, (ii) linearly varying load and (iii) sinusoidally distributed load. The results were compared with the solutions computed by the finite element method (FEM) and those obtained by the authors using the variational iterative method (VIM). In each case, it was found that the difference with reference to the existing one does not exceed 3%, which testifies the effectiveness of the DTM used. Nevertheless, it should be emphasized that the number of terms of the approximation series used is fairly large and therefore the calculation of higher critical loads can be very time-consuming.

scholarly journals STUDI EKSPERIMENTAL KUAT LENTUR BAJA PROFIL I KOMPAK SIMETRIS GANDA BERDASARKAN RSNI 03-1729-201X

1970 ◽  
Vol 6 (2) ◽  
pp. 99-105
Author(s):  
Redaksi Tim Jurnal
Keyword(s):  
Flexural Strength ◽  
Cross Section ◽  
Experimental Testing ◽  
Point Load ◽  
National Standard ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Element Analysis ◽  
Long Span ◽  
The Stability

The danger of buckling and instability structures easily occurs on the steel beam structure, it will make the structure fails before it reaches the cross section ultimate capacity.In that case the strength of a beam is not only determined by cross-section ultimate capacity. The instability of the structure causes lateral torsional buckling eventhough there is no torque on the beam. There is one way to support the stability of the beam; by installing lateral support on its side. This research is intended to obtain information about flexural strength by comparing the theoretical results based on SNI 03-1729-2002 and (Indonesian National Standard Draft) RSNI 03-1729.1- 201x with the results of experimental testing and finite element analysis results (using the ABAQUS program). The flexural specimens which are studied are in the long-span with a length of 3.3 meters span test. The loading uses three-point load system. The results of the test show information that flexural strength for the long-span specimen from experimental test results has the smallest difference of 33.18% of the theoretical result. As for analysis with FEM also hasthe same difference of 33.18% with the experimental results. Failure that occurs for long-span specimen is due to lateral torsional buckling failures.

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