Proposed rules for determining allowable compressive stresses for cylinders, cones, spheres, and formed heads

The purpose of this report is to propose alternative rules to those given in UG-23(b), UG-28, UG-29, UG-33 and Appendix 1--8 of ASME (1992a) for determining allowable compressive stresses for unstiffened and ring stiffened circular cylinders and cones and unstiffened spherical, ellipsoidal and torispherical heads. The allowable stress equations are based upon theoretical buckling equations which have been reduced by knockdown factors and by plasticity reduction factors which were determined from tests on fabricated shells. This report expands the coverage of load conditions and shell geometries and includes equations for combinations of loads which are not given in ASME (1992a). The proposed rules also apply to shells with higher D/t ratios. Allowable compressive stress equations are presented for cylinders and cones subjected to uniform axial compression, to bending moment applied over the entire cross-section, to external pressure, to loads which produce in-plane shear stresses and to combinations of these loads. Allowable compressive stress equations are presented for formed heads which are subjected to loads which produce unequal biaxial stresses as well as equal biaxial stresses. More accurate equations are given for determining the size of stiffening rings.