Ultimate strength characteristics of unstiffened cylindrical shell in axial compression

Abstract

Cylindrical shell is a common structural design solution in many engineering fields, such as the foundation supporting structures and buoyant column of the offshore wind turbine in the maritime sector. Operating in an ocean environment, these cylindrical shell structures need to withstand a combination of axial compression, bending moment, torsion and external pressure. This study contributes a parametric investigation for unstiffened cylindrical shells subjected to axial compression. Emphasis is placed on the ultimate strength characteristics and their relation with the initial geometric imperfection. The nonlinear finite element method is adopted by considering geometric and material nonlinearities in conjunction with an arc-length incrementation to solve the governing equilibrium equation. The numerical prediction is compared with the prevailing code-based approach, i.e. DNV, ABS, API and Eurocode. This study shows that the ultimate strength of unstiffened cylindrical shells in axial compression is highly sensitive to initial geometric imperfection. The code-based formulae appear to be overly conservative for predicting the ultimate compressive strength of cylindrical shells.