IHS ESDU Flexural properties of stringer sections (lipped and unlipped angles, channels and Z-sections). STRUCT 01.00.01

ESDU Struct 01.00.01 provides graphs, and the formulae from which they were calculated, for the moment of inertia of uniform thickness sections non-dimensionalised by the section area squared. For the channel- and Z-sections the curves are plotted against the flange width to web depth ratio for various values of web depth to thickness ratio. Superimposed are limiting values of flange width to thickness ratio, the lower value corresponding to premature lateral instability and the higher value to lateral instability of the flanges. Three graphs are given, one applying to unlipped sections and the others to values of lip width to web depth ratio of 0.1 and 0.2. For the angle sections, the curves are plotted against lip width to flange width ratio (which can be zero) for various values of flange width to thickness ratio. Superimposed are limiting values of lip width to thickness ratio, the lower value corresponding to premature lateral instability of the flange and the higher value to lateral instability of the lips. The data are for sections with sharp corners but may be applied when there is a radius, provided the true area of the section is used. The derivation assumes the stringer is constrained to bend in a plane along its length perpendicular to the plane of the flanges for the channel- and Z-sections and in the plane of a flange for the angle sections; thus the moment of inertia relates not to the unconstrained strut but to an axis through the centroid of the section and perpendicular to the plane in which it is constrained to bend.