Simplified methods for the inelastic analysis and reliability assessment of stiffened shells

Abstract

Simplified methods for predicting the resistance of stiffened axisyranetric shells are presented. A uniform internal static pressure is considered and strain ductility is taken as the failure criteria. The development of these methods is based upon limit analysis theory and takes into account the effects of large deformations. Twelve axisymmetric models are analyzed using the finite element technique and the results are used in the calibration of the simplified solution. An analysis of a typical pressure vessel is performed by the proposed and the finite element methods. The results of the pressure vessel analy­ sis, as well as those for the twelve models, illustrate the agreement between the finite element and the simplified methods. Introduction The problem of evaluating the resistance of stiffened axisymmetric shells under uniform internal pressure is an important one, particular­ ly with regard to steel containment vessels for nuclear power plants. The solution could require a three-dimensional finite element analysis which takes into account material and geometric nonlinear effects. While this is theoretically possible, it would be expensive in terms of computer time; therefore, another alternative is useful. Additional­ ly, finite element models are difficult to incorporate into reliability predictions. An alternative approach is to use basic shell theory in conjunction with the limit analysis techniques to solve for the result­