Buckling of Stiffened Webs by Local Edge Loads

A finite strip method is used for analysing the buckling of longitudinally stiffened web plates subjected to transverse local edge loading. The probLem is of particular importance for box girders, which have relatively weak flanges for resisting this type of buckling. Critical loads are obtained for square webs stiffened by single asymmetric longitudinal stiffeners positioned at one fifth of the depth from the loaded edge. A sufficient range of stiffener geometries is considered to enable the separate influences of the bending and torsional rigidities to be determined and two simple design rules are proposed. The first gives the lower limit on the bending rigidity for which the stiffener remains straight in the buckled configuration. The second gives the buckling strength of the web as a function of the torsional rigidty of the stiffener.