A Method for Including Ovalization Effects of Tubular Member on Cross-Section Properties

摘要

This paper presents the calculation of stiffness matrix of an ovalized tubular member modeled as a 3D beam element, which can be used in offshore steel structures and pipelines in general. Harmonic functions are used to represent the variation of ovalization along the circumference of the cross-section and polynomial functions are used for ovalization rates along the member axis. The stiffness matrix is stated in the form of augmentation so that the original form does not change during an iteration process if needed to apply. This form is especially useful in dynamic analysis, because the augmented part becomes frequency dependent and needs to be calculated at each frequency variation. A pipeline example is presented to demonstrate the effect of ovalization on response quantities.