Buckling of webs with openings

The buckling of the webs of steel beams is investigated analytically and experimentally. The influence of circular and rectangular holes on the buckling strength of beams of the dimensions normally used in building structures is considered. The buckling analysis is based on an energy method, and relies on finite element analysis for the in-plane stress distributions in the perforated webs. For the proportions of the beams considered, buckling takes place after the initiation of plasticity in the web and this is considered in the analysis. Comparison of analytical results with results of tests on five beams shows excellent agreement. It is shown that for these beams, the range of slenderness for which elasto-plastic buckling occurs is quite limited, and that below a web slenderness of 50, or in some cases more, holes of the shape and size considered will not lead to buckling prior to the development of full plastic strength.