Lateral-Torsional Buckling Analysis for Doubly Symmetric Tubular Flange Composite Beams with Lateral Bracing under Concentrated Load

Tubular flange composite beams are increasingly applied in modern bridge structures. In order to investigate the overall stability behavior of doubly symmetric tubular flange composite beams with lateral bracing under concentrated load, the analysis of elastic lateral-torsional buckling is conducted by the energy variation method. The analytical solution of critical moment of doubly symmetric tubular flange composite beams with lateral bracing is obtained. Meanwhile, the simplified calculation formula of critical moment is fitted by 1stOpt software based on 26,000 groups of data, and the accuracy is verified by the finite element method. It is found that, the critical moment rises obviously with increasing lateral bracing stiffness, and adding lateral bracing to doubly symmetric tubular flange composite beams is beneficial to improve the overall stability in engineering practice. Finally, the influence of several parameters including concrete strength, span, steel ratio of flange and height-thickness ratio of web are studied. The results show that the concrete strength and the web height-thickness ratio have a weak influence on critical moment of elastic lateral-torsional buckling, while the influence of span-depth ratio and flange steel ratio is very significant.

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Elastic Critical Moment of Lateral-Distortional Buckling of Steel-Concrete Composite Beams under Uniform Hogging Moment

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455419500792 ◽

2019 ◽

Vol 19 (07) ◽

pp. 1950079 ◽

Cited By ~ 6

Author(s):

João Victor Fragoso Dias ◽

Janaina Pena Soares Oliveira ◽

Adenilcia Fernanda Grobério Calenzani ◽

Ricardo Hallal Fakury

Keyword(s):

Numerical Models ◽

Concrete Slab ◽

Horizontal Displacement ◽

Composite Beams ◽

Bottom Flange ◽

Distortional Buckling ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Average Deviation ◽

Critical Moment

Great attention has been given in the last few years to steel–concrete composite beams due to the gains in strength that can be obtained with the small cost of installing a shear connection between the steel profile and the concrete slab. In continuous and semicontinuous composite beams close to the internal supports, hogging bending moments are developed and the compressed bottom flange may buckle laterally in an unstable way known as the lateral-distortional buckling, characterized by a horizontal displacement and twist of the bottom flange with an out-of-plane distortion of the web. In the literature, several formulations were proposed to determine the critical moment for this type of buckling. Among them, some of the most relevant are presented by [K. Roik, G. Hanswille and J. Kina, Solution for the lateral torsional buckling problem of composite beams (in German), Stahlbau 59 (1990)] and [G. Hanswille, J. Lindner and D. Munich, Lateral torsional buckling of composite beams (in German), Stahlbau 67 (1998)]. In the present work, a new procedure is developed to determine the elastic critical moment of lateral–distortional buckling of composite beams under uniform hogging moment. To assess and calibrate this procedure, 7[Formula: see text]772 numerical models were analyzed by the finite element code ANSYS and the results were compared with the ones obtained from the new proposed formulas. The procedure presented excellent agreement with the numerical results, with an average deviation of 2.33% from the computational simulations. The formulations of [K. Roik, G. Hanswille and J. Kina, Solution for the lateral torsional buckling problem of composite beams (in German), Stahlbau 59 (1990)] and [G. Hanswille, J. Lindner and D. Munich, Lateral torsional buckling of composite beams (in German), Stahlbau 67 (1998)] did not lead to such satisfactory results, presenting an average deviation of 12.41% and 16.51%, respectively.

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Elastic critical moment of continuous composite beams with a sinusoidal-web steel profile for lateral-torsional buckling

Engineering Structures ◽

10.1016/j.engstruct.2016.01.021 ◽

2016 ◽

Vol 113 ◽

pp. 121-132 ◽

Cited By ~ 9

Author(s):

Janaina Pena Soares de Oliveira ◽

Adenilcia Fernanda Grobério Calenzani ◽

Ricardo Hallal Fakury ◽

Walnório Graça Ferreira

Keyword(s):

Composite Beams ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Critical Moment

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A comparative study of beam design curves against lateral torsional buckling using AISC, EC and SP

Structural Mechanics of Engineering Constructions and Buildings ◽

10.22363/1815-5235-2019-15-1-25-32 ◽

2019 ◽

Vol 15 (1) ◽

pp. 25-32 ◽

Cited By ~ 2

Author(s):

Vera V Galishnikova ◽

Tesfaldet H Gebre

Keyword(s):

Steel Structures ◽

Reduction Factor ◽

Steel Beams ◽

Steel Beam ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Vertical Loading ◽

Beam Design ◽

Overall Stability

Introduction. Structural stability is an essential part of design process for steel structures and checking the overall stability is very important for the determination of the optimum steel beams section. Lateral torsional buckling (LTB) normally associated with beams subject to vertical loading, buckling out of the plane of the applied loads and it is a primary consideration in the design of steel structures, consequently it may reduce the load currying capacity. Methods. There are several national codes to verify the steel beam against LTB. All specifications have different approach for the treatment of LTB and this paper is concentrated on three different methods: America Institute of Steel Construction (AISC), Eurocode (EC) and Russian Code (SP). The attention is focused to the methods of developing LTB curves and their characteristics. Results. AISC specification identifies three regimes of buckling depending on the unbraced length of the member ( Lb ). However, EC and SP utilize a reduction factor (χ LT ) to treat lateral torsional buckling problem. In general, flexural capacities according to AISC are higher than those of EC and SP for non-compact sections.

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