Comparison Study of Various Buckling and Ultimate Strength Assessment Methodologies for Stiffened Panels in Offshore Structures

Abstract

Strength of offshore structures including FPSOs consists broadly of three aspects which are global intact and damaged strength, and local strength. Any of these strength aspects can be assessed by either prescriptive rule or finite element analysis (FEA). While many considerations relate to behavior in the linear elastic regime, the buckling and ultimate strength of both structural components (plate and stiffened panels) and structural systems can involve material and geometric nonlinearity behavior beyond the elastic region. With the development of computers and robust methods for nonlinear FEA, there has been a tremendous increase in the number of studies of structures under plastic or elasto-plastic behavior. However, even with today’s computers and software, nonlinear FEA of offshore structures remains complex and is not routinely applied in design analysis. Considerable effort therefore continues to be devoted to the development of simplified methods for rapid structural assessment and design analysis, instead of lengthy and complex nonlinear FEA. In this paper, various bucking and ultimate strength methodologies for plate and stiffener panels are first introduced. Each method is then compared with collected test data for buckling and ultimate strength of plate panels and stiffeners. Finally, conclusions are summarized based on the comparison study.