A commonly encountered condition is a flange with one edge stiffened by a web, the other by an edge stiffener (Fig. 10.7). To determine its effective width for load capacity determination, one of three cases must be considered. The case selection depends on the relation between the flange flat width-to-thickness ratio, w/t, and the parameter S defined as

For each case an equation will be given for determining Ia, the moment of inertia required for a stiffener adequate so that the flange element behaves as a stiffened element, IS is the moment of inertia of the full section of the stiffener about its centroidal axis, parallel to the element to be stiffened. AS is the effective area of a stiffener of any shape, calculated by methods previously discussed. The reduced area of the stiffener to be used in section property calculations is termed AS and its relation to AS is given for each case. Note that for edge stiffeners, the rounded corner between the stiffener and the flange is not considered as part of the stiffener in calculations. The following additional definitions for a simple lip stiffener illustrated in Fig. 10.7 apply. The effective width dS is that of the stiffener calculated according to Arts. 10.9.1 and 10.9.2. The reduced effective width to be used in section property