Study On Advanced Buckling Analysis Methods Of Stiffened Panels

Stiffened panels are basic strength members of ship and offshore structures. Accurate calculation of buckling and ultimate strength of stiffened panels provides the basis for safety accounting of ship and offshore structures. With the development of large scale ship and offshore structures, on one side stiffened panels may suffer complicated and extreme loads, on the other side the number of stiffened panels needed to be checked is huge. The International Association of Classification Societies(IACS) required in the common structural rules for double hull oil tankers(CSR-OT 2006) that the strength of stiffened panels should be checked using advanced buckling analysis methods. Based on research topic of China Classification Society(CCS), this paper conducts study on methods of advanced buckling analysis and development of the software with autonomous intellectual property which has important theoretical sense and engineering utilization value on safety accounting of ship and offshore structures.At first, this paper outlines current situation of method study of buckling and ultimate strength of stiffened panels and introduces the main software of advanced buckling analysis. Then, ultimate strength study of rectangular plates and stiffened panels, model test verification and software test are conducted. The main research work of this paper is as follows:(1) Based on elastic large deflection theory and rigid plastic analysis(EPM) of plates, ultimate strength calculation method of rectangular plates considering initial imperfections and combined biaxial compression and lateral loads is given. In order to verify the rationality and accuracy of EPM of plates, ultimate strength analysis is conducted on 20 plates of model test. The effect of initial imperfections, transverse stress and lateral pressure is also discussed.(2) Five collapse modes are analyzed, i.e. overall buckling of the orthogonal stiffened panel, overall buckling of the longitudinal stiffened subpanel, local buckling or yielding of the longitudinal stiffener with the plate, tripping of the longitudinal stiffener and gross yielding. Ultimate strength calculation method of stiffened panels is given based on elastic large deflection theory and rigid plastic analysis of beams and orthotropic plates. In order to verify the rationality and accuracy of EPM of stiffened panels, ultimate strength analysis is conducted on 21 stiffened panels of model test.(3) Modeling requirement and calculation process of nonlinear finite element method(FEM) are outlined. Stiffened panels, loading equipment and results of GL model test are introduced. Comparative study on ultimate strength of 4 stiffened panels of GL model test of is conducted using FEM and EPM.(4) The functional module and calculation process of EPM software is introduced. Comparative calculation on serial standard examples of background document of CSR-OT is conducted using EPM software and DNV’s software(PULS). Biaxial stress capacity of four typical stiffened panels is calculated using EPM software, PULS and harmonized common structural rules(HCSR) method. The reliability and capacity of EPM software is tested.