A stiffened shear web, consisting of a thin plate (referred to simply as the web) attached to longitudinal members (or flanges) and supported by a series of transverse stiffeners, buckles in a mode involving both the web and stiffeners, at a shear stress which also depends on the restraint between the web and flanges. With increasing stiffener size changes in the mode of buckling occur until, at a certain critical value of the flexural stiffness of the stiffener, buckling is largely confined to the web between stiffeners, and the buckling coefficient is then practically constant. The buckling coefficient reduces to that of an unstiffened flat plate with decreasing stiffener size.

Engineering Sciences Data Item 02.03.02 plots buckling coefficients for long shear webs with uniform, equally-spaced stiffeners. The curves are based on work by Stein and Fralich, for stiffeners of zero torsional rigidity and simply-supported longitudinal edges, and on a more recent series of papers by Cook and Rockey (listed in the Data Item) which extend the analysis to clamped, as well as simply-supported, webs and also include the torsional rigidity of the stiffeners.