A Coupled Behaviour of Web and Flange on Bending Buckling of the Web of Steel Box Girder

In general, a web of the steel box girder is designed as an independent. However, in actual behaviour, since the web and the flange behave in couple, the web is considered to have a higher bending buckling strength than the designed standard due to the restraint by the flanges. Therefore, horizontal stiffeners for the web of the steel box girder might be omitted. In this study, focusing on the effect of the coupled behaviour of the web and flange on the bending buckling strength of the web of a box girder, FE analyses were carried out of steel box girder model with different structural configuration and of a panel model under identical boundary conditions as the design. From these results, it was found that the web of box girders without horizontal stiffeners have a higher bending buckling strength than the panel model due to restraint by the top of end of the web by the flange. In the case that buckling parameters of the flange are smaller than those critical buckling parameters, the influence of the bending buckling of the web of the box girder on the buckling strength of the flange is slight.