Short Thin‐Walled Cylinders Under Combined Loading

Abstract

The paper presents a rational method for predicting the load‐carrying capacity of a short, thin‐walled cylinder under combined loading. The elastic critical stresses for the perfect cylinder are found from the codes and multiplied by the knock‐down factors to account for the buckle imperfection. The factors are derived from the classical theory and correspond to the actual imperfection amplitude. The axial and hydrostatic pressure causes membrane stresses and bending moments due to the oval imperfection of the cross section. These moments are calculated by a plate theory, where the stiffness is reduced due to the limited value of the elastic critical stresses of the imperfect cylinder. The capacity is determined by inserting these moments and membrane stresses into von Mise's yield equation. The theory provides a good and slightly conservative estimate of the experimental results and explains the significant variation from code to code of the interaction curves. The results are easily applied to the practical design of offshore structures.