Contribution to lateral torsional buckling of girders with rotational restraints

Contribution to lateral torsional buckling of girders with rotational restraints

Kapitola, resp. kapitoly v odborné knize

The instability case of lateral torsional buckling (LTB) under bending load is known to be of decisive importance in the design of beams with open cross-sections, mainly H- and I-shaped profiles, expressed by a lateral displacement v and simultaneous torsion of the member axis J. The restraint of one or both of these deformation components represents an effective and practice-oriented method to stabilize beams against LTB. It is typically provided by purlins, roof panels or cladding. The practical consideration of this effect is based on regulations in the current version of EN 1993-1-1:2010, Annex BB. With the introduction of the 2nd generation of prEN1993-1-1:2020 (currently a draft version) a new formulation is presented for the instability problem of lateral-torsional buckling. The effects of those innovations on the calculation of the minimum required torsional stiffness CJ were initially investigated by the authors for a very limited amount of load cases and profiles. It was shown that the planned tightening of the regulations on the minimum rotational stiffness in prEN 1993-1-1, Annex D is unne- cessary and the currently valid specifications in the National Annex of DIN EN 1993-1-1 are also sufficiently accurate for practical use and do not contradict the newly introduced regulations for torsional buckling. Nevertheless, these conclusions were made on the basis of a restricted range of results and remain unconfirmed without further investigations. Therefore, this paper presents additional results based on nonlinear finite-element simulations using a selected range of load cases as well as a wider range of H- and I-shaped profiles.

The instability case of lateral torsional buckling (LTB) under bending load is known to be of decisive importance in the design of beams with open cross-sections, mainly H- and I-shaped profiles, expressed by a lateral displacement v and simultaneous torsion of the member axis J. The restraint of one or both of these deformation components represents an effective and practice-oriented method to stabilize beams against LTB. It is typically provided by purlins, roof panels or cladding. The practical consideration of this effect is based on regulations in the current version of EN 1993-1-1:2010, Annex BB. With the introduction of the 2nd generation of prEN1993-1-1:2020 (currently a draft version) a new formulation is presented for the instability problem of lateral-torsional buckling. The effects of those innovations on the calculation of the minimum required torsional stiffness CJ were initially investigated by the authors for a very limited amount of load cases and profiles. It was shown that the planned tightening of the regulations on the minimum rotational stiffness in prEN 1993-1-1, Annex D is unne- cessary and the currently valid specifications in the National Annex of DIN EN 1993-1-1 are also sufficiently accurate for practical use and do not contradict the newly introduced regulations for torsional buckling. Nevertheless, these conclusions were made on the basis of a restricted range of results and remain unconfirmed without further investigations. Therefore, this paper presents additional results based on nonlinear finite-element simulations using a selected range of load cases as well as a wider range of H- and I-shaped profiles.

Lateral-torsional buckling; restraint; beam

Lateral-torsional buckling; restraint; beam

MÜLLER, A.; TARAS, A.; VILD, M.

07.08.2025

Taylor & Francis Group

London

9781003677895

Engineering Materials, Structures, Systems and Methods for a More Sustainable Future

287

292

6

http://dx.doi.org/10.1201/9781003677895-47