An experimental study of the lateral stability of castellated steel beams is described. Although an extensive survey of the literature on castellated beams showed that this subject had not been investigated experimentally before, some useful information was obtained from tests conducted to investigate in-plane response. This showed that the lateral-torsional buckling failure of castellated beams was similar to that of equivalent plain-webbed beams. Two series of tests were conducted: a preliminary series on specially manufactured small-scale specimens designed to provide qualitative data and a second series of eight full-scale tests using commercially produced beams. The results of the preliminary series, subsequently confirmed by the main series of tests, suggested that the presence of the castellations had negligible effect on lateral buckling behaviour. Comparisons between the experimentally obtained maximum loads for the main series and the strengths predicted by the proposed draft Code for structural steelwork B/20 proved generally satisfactory, provided cross-sectional properties at a castellation were used in the calculations. Similar results were obtained for the two-stage procedure of BS 449, whereas the use of Table 3 in that document was shown to lead to rather low load factors.
D.A. Nethercot and D. Kerdal