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

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.

Download Full-text

Lateral Torsional Buckling Strengths of Stepped Beams at Midspan Exposed to Elevated Temperature

International Journal of Steel Structures ◽

10.1007/s13296-020-00427-0 ◽

2020 ◽

Vol 20 (6) ◽

pp. 2028-2037

Author(s):

Shane Alolod ◽

Jongsup Park ◽

Deokhee Won

Keyword(s):

Elevated Temperature ◽

Lateral Torsional Buckling ◽

Torsional Buckling

Download Full-text

The effects of residual stresses and strains on lateral-torsional buckling behavior of cold-formed steel channel and built-up I-sections beams

International Journal of Structural Integrity ◽

10.1108/ijsi-07-2018-0044 ◽

2019 ◽

Vol 10 (2) ◽

pp. 230-243

Author(s):

Mohammad Zaman Kabir ◽

Mehdi Parvizi

Keyword(s):

Residual Stresses ◽

Major Effect ◽

Buckling Analysis ◽

Roll Forming ◽

Lateral Torsional Buckling ◽

Forming Process ◽

Torsional Buckling ◽

Content Type ◽

Cold Formed Steel ◽

Residual Stresses And Strains

Purpose The purpose of this paper is to focus on the influences of residual stresses which were induced during roll-forming sections on lateral-torsional buckling of thin-walled cold-formed steel channel and built-up I-sections beams. Built-up I section is made up of two back-to-back cold-formed channel beams. In this direction, at the primary stage, the roll-forming process of a channel section was simulated in ABAQUS environment and the accuracy of the result was verified with those existing experiments. Residual stresses and strains in both longitudinal and circumferential transverse directions were extracted and considered in the lateral-torsional buckling analysis under uniform end moments. The contribution of the current research is devoted to the numerical simulation of the rolling process in ABAQUS software enabling to restore the remaining stresses and strains for the buckling analysis in the identical software. The results showed that the residual stresses decrease considerably the lateral-torsional buckling strength as they have a major impact on short-span beams for channel sections and larger span for built-up I sections. The obtained moment capacity from the buckling analysis was compared to the predictions by American Iron and Steel Institute design code and it is found to be conservative. Design/methodology/approach This paper has explained a numerical study on the roll-forming process of a channel section and member moment capacities related to the lateral-torsional buckling of the rolled form channel and built-up I-sections beams under uniform bending about its major axis. It has also investigated the effects of residual stresses and strains on the behaviour of this buckling mode. Findings The residuals decrease the moment capacities of the channel beams and have major effect on shorter spans and also increase the local buckling strength of compression flange. But the residuals have major effect on larger spans for built-up I sections. It could be seen that the ratio of moment (with residuals and without residuals) for singly symmetric sections is more pronounced than doubly symmetric sections. So it is recommended to use doubly symmetric section of cold-formed section beams. Originality/value The incorporation of residual stresses and strains in the process of numerical simulation of rolled forming of cold-formed steel sections under end moments is the main contribution of the current work. The effect of residual stresses and strains on the lateral-torsional buckling is, for the first time, addressed in the paper.

Download Full-text