Ultimate strength models for spherical shells under external pressure: a comparative study
Liang Zhao, Yong Bai
Abstract
The ultimate strength of spherical shells under external pressure has been an attractive topic in the field of marine structures. However, recent studies have revealed that the current theoretical approaches are hardly compatible with the actual hulls, which indicates that the ultimate strength models still need to be reevaluated and unified. To address this challenge, a comparative study has been conducted in this paper. Various analytical approaches and codified rules are compared through screened experiment data that have realistic imperfections and different shape parameters in the range generally applied for marine structures. The model evaluation criteria have been established by implementing statistical model uncertainty factors in terms of bias and coefficient of variation. A comparison of the results has been made from three different aspects including shell shape, R/t and geometrical parameters to evaluate their performance. Based on the calculation outcome, analysis has been made to study the theory behind those models and determine their limitations and recommended application range.