Flexural strength of steel girders with perforated web and tubular compression flange

Abstract

Lateral torsional buckling, that pronounced for the case of laterally unrestrained compression flange, reduces the moment capacity of steel I-girders. To recover this weakening, the approach is to replace the conventional plate flange with a rectangular tube which has higher lateral stiffness thus valuable against lateral buckling. At the same time, web openings in this section are introduced to enable passing of services but causing strength reduction. Girders with tubular flange plus web openings are yet not discussed in publications. In this paper, FEM is performed to fill this gap studying different web and flange slenderness classifications as well as parameters such as size of web openings, spacing, and location. The results for solid web are found more comparable to EC than AISC, enabling good prediction of the flexural capacity. By introducing web openings, the flexural capacity is reduced by 10%-20%, closer to the higher side for large opening diameters located near the compression flange. The oval shape of the openings has less reduction strength while the square is unfavorable. Tubular flange girders, even if perforated, proves its flexural strength enhancement and considerable reduction of the material than the plate flange girders. This section behaves better regarding the carbon emissions.