Lateral-torsional buckling resistance of cellular beams

The evenly spaced circular web openings in I-section cellular beams have an advantageous effect on the material use if these beams are loaded in strong-axis bending. However, not all aspects of the behaviour of such beams have been studied adequately, such as the lateral–torsional buckling failure. For the latter failure mode, the existing design approaches conflict.

Furthermore, the detrimental effect of the modification of the residual stresses by the production process, as recently demonstrated by the authors in previous work, was never taken into account.

In this paper, the lateral–torsional buckling behaviour of cellular beams is investigated using a numerical model that was validated based on experimental results. In this model, the effect of the modified residual stress pattern was aptly taken into account. Using the results of the parametric study, a preliminary design approach was proposed. This approach is based on the currently existing European guidelines for the calculation of the lateral–torsional buckling resistance of I-section beams, but with a modified calculation of the cross-sectional properties and a modified buckling curve selection.