Lateral-Torsional Buckling Modification Factors in Steel I-Shaped Members: Recommendations Using Energy-Based Formulations

Research output: Contribution to journalArticleTransferpeer review

Authors

Research Organisations

External Research Organisations

  • Indian Institute of Technology Madras (IITM)
View graph of relations

Details

Original languageEnglish
Pages (from-to)141-158
Number of pages18
JournalEngineering journal
Volume61
Issue number3
Publication statusPublished - 1 Jul 2024

Abstract

Lateral torsional buckling (LTB) is of concern in long-span flexural members, particularly in the negative flexure regions of continuous-span, steel I-shaped members and during construction. While the elastic critical LTB capacity of a simply supported I-shaped member subjected to uniform moment has a closed-form solution, most LTB modification factors for beams subjected to moment gradients in the literature are empirical and work well only for specific loading and boundary conditions. This paper investigates the suitability of the different LTB modification factors in literature and design specifications for various loading and boundary conditions, accomplished via comparisons with analytical solutions using the Rayleigh-Ritz method and numerical solutions from finite element analyses. The analytical LTB modification factors are derived for doubly symmetric I-shaped members with different combinations of ideal flexural and torsional boundary conditions (simply supported and fixed) and subjected to different loading scenarios. The validity of the LTB modification factors determined using the Rayleigh-Ritz method and other formulae in the literature are also assessed for realistic intermediate restraint conditions, which are neither fully pinned nor fixed, by examining laterally continuous beams. Demonstrating that current design specifications for elastic critical LTB modifications are overly conservative for beams with complete or partial warping fixity, the authors recommend practical and simple alternatives to design such beams.

Keywords

    continuous beams, lateral torsional buckling, LTB modification factor, Rayleigh-Ritz method, warping restraints

ASJC Scopus subject areas

Cite this

Lateral-Torsional Buckling Modification Factors in Steel I-Shaped Members: Recommendations Using Energy-Based Formulations. / Nayak, Namita; Anilkumar, P. M.; Subramanian, Lakshmi.
In: Engineering journal, Vol. 61, No. 3, 01.07.2024, p. 141-158.

Research output: Contribution to journalArticleTransferpeer review

Download
@article{5e767bdfc28e40f78e5cd0b7897c4d95,
title = "Lateral-Torsional Buckling Modification Factors in Steel I-Shaped Members: Recommendations Using Energy-Based Formulations",
abstract = "Lateral torsional buckling (LTB) is of concern in long-span flexural members, particularly in the negative flexure regions of continuous-span, steel I-shaped members and during construction. While the elastic critical LTB capacity of a simply supported I-shaped member subjected to uniform moment has a closed-form solution, most LTB modification factors for beams subjected to moment gradients in the literature are empirical and work well only for specific loading and boundary conditions. This paper investigates the suitability of the different LTB modification factors in literature and design specifications for various loading and boundary conditions, accomplished via comparisons with analytical solutions using the Rayleigh-Ritz method and numerical solutions from finite element analyses. The analytical LTB modification factors are derived for doubly symmetric I-shaped members with different combinations of ideal flexural and torsional boundary conditions (simply supported and fixed) and subjected to different loading scenarios. The validity of the LTB modification factors determined using the Rayleigh-Ritz method and other formulae in the literature are also assessed for realistic intermediate restraint conditions, which are neither fully pinned nor fixed, by examining laterally continuous beams. Demonstrating that current design specifications for elastic critical LTB modifications are overly conservative for beams with complete or partial warping fixity, the authors recommend practical and simple alternatives to design such beams.",
keywords = "continuous beams, lateral torsional buckling, LTB modification factor, Rayleigh-Ritz method, warping restraints",
author = "Namita Nayak and Anilkumar, {P. M.} and Lakshmi Subramanian",
note = "Publisher Copyright: {\textcopyright} 2024, American Institute of Steel Construction Inc.. All rights reserved.",
year = "2024",
month = jul,
day = "1",
doi = "10.62913/engj.v61i3.1328",
language = "English",
volume = "61",
pages = "141--158",
journal = "Engineering journal",
issn = "0013-8029",
publisher = "American Institute of Steel Construction Inc.",
number = "3",

}

Download

TY - JOUR

T1 - Lateral-Torsional Buckling Modification Factors in Steel I-Shaped Members

T2 - Recommendations Using Energy-Based Formulations

AU - Nayak, Namita

AU - Anilkumar, P. M.

AU - Subramanian, Lakshmi

N1 - Publisher Copyright: © 2024, American Institute of Steel Construction Inc.. All rights reserved.

PY - 2024/7/1

Y1 - 2024/7/1

N2 - Lateral torsional buckling (LTB) is of concern in long-span flexural members, particularly in the negative flexure regions of continuous-span, steel I-shaped members and during construction. While the elastic critical LTB capacity of a simply supported I-shaped member subjected to uniform moment has a closed-form solution, most LTB modification factors for beams subjected to moment gradients in the literature are empirical and work well only for specific loading and boundary conditions. This paper investigates the suitability of the different LTB modification factors in literature and design specifications for various loading and boundary conditions, accomplished via comparisons with analytical solutions using the Rayleigh-Ritz method and numerical solutions from finite element analyses. The analytical LTB modification factors are derived for doubly symmetric I-shaped members with different combinations of ideal flexural and torsional boundary conditions (simply supported and fixed) and subjected to different loading scenarios. The validity of the LTB modification factors determined using the Rayleigh-Ritz method and other formulae in the literature are also assessed for realistic intermediate restraint conditions, which are neither fully pinned nor fixed, by examining laterally continuous beams. Demonstrating that current design specifications for elastic critical LTB modifications are overly conservative for beams with complete or partial warping fixity, the authors recommend practical and simple alternatives to design such beams.

AB - Lateral torsional buckling (LTB) is of concern in long-span flexural members, particularly in the negative flexure regions of continuous-span, steel I-shaped members and during construction. While the elastic critical LTB capacity of a simply supported I-shaped member subjected to uniform moment has a closed-form solution, most LTB modification factors for beams subjected to moment gradients in the literature are empirical and work well only for specific loading and boundary conditions. This paper investigates the suitability of the different LTB modification factors in literature and design specifications for various loading and boundary conditions, accomplished via comparisons with analytical solutions using the Rayleigh-Ritz method and numerical solutions from finite element analyses. The analytical LTB modification factors are derived for doubly symmetric I-shaped members with different combinations of ideal flexural and torsional boundary conditions (simply supported and fixed) and subjected to different loading scenarios. The validity of the LTB modification factors determined using the Rayleigh-Ritz method and other formulae in the literature are also assessed for realistic intermediate restraint conditions, which are neither fully pinned nor fixed, by examining laterally continuous beams. Demonstrating that current design specifications for elastic critical LTB modifications are overly conservative for beams with complete or partial warping fixity, the authors recommend practical and simple alternatives to design such beams.

KW - continuous beams

KW - lateral torsional buckling

KW - LTB modification factor

KW - Rayleigh-Ritz method

KW - warping restraints

UR - http://www.scopus.com/inward/record.url?scp=85200248289&partnerID=8YFLogxK

U2 - 10.62913/engj.v61i3.1328

DO - 10.62913/engj.v61i3.1328

M3 - Article

AN - SCOPUS:85200248289

VL - 61

SP - 141

EP - 158

JO - Engineering journal

JF - Engineering journal

SN - 0013-8029

IS - 3

ER -

By the same author(s)