Stability of web plates in W-shape columns accounting for flange/web interaction

North American, British and European codes of practice provide design equations for local buckling limit state of W-shape columns, by assuming the web and the flanges are either simply supported or clamped along their lines of junctions. In doing so, the geometric interactions between the web and flange are ignored. In practice, the column webs rarely have simply supported or clamped edges but are rather elastically restrained against rotation. In addition, the in-plane boundary conditions of the web, which is dictated by geometric properties of the flanges, have a great influence on its buckling and post-buckling stiffness. The paper highlights the influence of the flange/web geometric proportions on the stability of web plates in W-shape columns under uniform compression. Results are obtained showing the influence of the flange/web thickness (tf/tw) on the buckling and post buckling stiffness of the web. Also, the influence of the flange/web width (bf/bw) on the web stability is highlighted. Graphs are presented showing the transitions between various “theoretical” boundary conditions by adjusting the flange/web geometric proportions. These graphs are useful to use in practice in order to achieve economical design of column section.