Elastic lateral-torsional buckling of cellular beams

Cellular beams are I-shaped steel sections with advantages provided by their circular web openings. This type of beam can have greater spans, be more slender and higher than the solid beams, being more prone to failure by lateral-torsional buckling. Given there is still no specific standard for cellular beams and owing to the importance of safety verification, this paper numerically investigated the lateral-torsional buckling of these beams. Considering the torsional constant as the most important parameter in the design of web-opening beams, this study proposes a new torsional constant and approaches four different calculation methods of weighted average torsional constants. The elastic critical moment of cellular beams was numerically modelled using ANSYS software and compared with analytical results according to European standards, varying the torsional constants. The weighted average torsional constant based on an equivalent area and using the proposed torsional constant was the most efficient, showing the best analytical results when compared with the numerical ones considering the load condition of constant bending moment. Furthermore, from all the geometric parameters evaluated, the height of the cellular beam was what most influenced the elastic critical moment of the cellular beams.