Web Buckling in Thin Webbed Castellated Beams

Tests are described in which 12 castellated beams were loaded to failure in order to study the buckling of the web post between openings. In 10 cases web-post buckling occurred. Finite-element analysis (FEM) of the web post, taking into account inelastic action, was used to predict the buckling loads. Also, graphical results were obtained based on a previously described analysis in which the web post was treated as a beam and the finite difference method was used to obtain the buckling loads. Both methods show very good correlation with the maximum test loads. Either of these methods provide a satisfactory basis for design, although the FEM results are superior because of the lower variability in the predictions. The graphical results provide general solutions covering a practical range of geometries, and can be considered suitable until the results of finite-element parameter studies become available.