Effective cross sections of asymmetric rings on cylindrical shells

Rings or ringbeams are often used to stiffen cylindrical tanks, silos, towers, and pressure vessels. A ring acts together with the axisymmetric shell to form a composite structure. The structural analysis of such a composite structure under general loadings is usually not simple, and often has to be numerical. Although the membrane stress in a symmetrical ring stiffener under axisymmetric loadings may be calculated from a simple effective ring analysis, no existing simple method is able to predict the bending stresses caused by either eccentric loading (bending moment) or the use of an asymmetric section as a ring stiffener. In this paper, the deformations of a general unsymmetrical ring stiffener are analyzed using linear shell bending theory. A new rational method of determining both the precise membrane and the bending stresses throughout the discrete ring stiffener using effective ring analysis is devised. The new method is suitable for use in a shell design standard.