COLLAPSE STRENGTH OF COMPLEX METAL SHELL INTERSECTIONS BY THE EFFECTIVE AREA METHOD

Cone-cone intersections and cone-cylinder intersections with or withou t ring stiffeners are common features in silos, tanks, pressure vessel s, piping components, and other industrial shell structures. Under int ernal or external pressure, these intersections are subject to high ci rcumferential membrane stresses as well as high bending stresses due t o the presence of a slope discontinuity. As a result, they are suscept ible to local plastic collapse. This paper first provides a summary of the effective area method initially proposed by Rotter for the plasti c limit loads of cone-cylinder intersections in silos. The method is t hen generalized for complex intersections of cones and cylinders under uniform pressure and improved by including the focal pressure effect. Results from the effective area method are compared with rigorous fin ite element results for a number of cases to demonstrate ifs accuracy. It is shown that the method is not only elegant and accurate, but als o leads to a single simple formula for different types of intersection s which is particularly suitable for codification purposes.