Design of Intermediate Ring Stiffeners for Column-Supported Cylindrical Steel Shells

A combination of a ring beam and an intermediate ring stiffener can be used for large silos to redistribute the stresses from the local support into uniform stresses in the shell. This paper explores the design requirements for intermediate ring stiffeners placed at or below the ideal location. Pursuant to this goal, the cylindrical shell below the intermediate ring stiffener is analyzed using the membrane theory of shells and the reactions produced by the stiffener on the shell are identified. Furthermore, the displacements imposed by the shell on the intermediate ring stiffener are obtained. These force and displacement boundary conditions are then applied to the intermediate ring stiffener to derive closed form expressions for the variation of the stress resultants around the circumference to obtain a strength design criterion for the stiffener. These analytical studies are then compared with complementary finite element analyses to verify closed-form design equations for ring stiffeners