| With the development of economic and the appearance of high strength materials, structural strength characterized by tension stress is not the main contradiction, while buckling and ultimate strength characterized by compression stress become to the main contradiction in structural design. Plates and stiffened plates are important components of ship structures, so it is important guarantee for improving ship safety and economy to hold the buckling and ultimate strenth correctly.Therefore, in order to satisfy the requirement of safe and robust ship of the industry and the shipping circles, ensure the maritime safety, protect ocean environment and pursue high quality ship, a single standard-Common Structural Rules (CSR) were delivered by IACS. There are more detailed regulations and more strict criterias in CSR. However, because of new Rules, dispute may exist and need to be checked up by the industry. So the paper makes some research on equivalent method about buckling strength assessment, and its main contents are as follows:Firstly, the basic theory and key technology referenced by ship structural plates buckling strength analysis is expatiated, the characteristic of plate buckling and Large Deflection Theory is analyzed. And the paper also makes some research on plate elastic buckling strength and ultimate capacity experienced formula considering the influence of kinds of objections.Secondly, taking unstiffened plate as an example, the paper applies finite element analysis to checking the validity of buckling assessment equivalent formulae of CSR including JTP (Joint Tanker Project) and JBP(Joint Bulk Carrier Project), carries out comparison between JTP and JBP Rules in buckling strength assessment, and analyzes the main reasons for error. The paper also provides reference for the harmonization of Common Structural Rules.Thirdly, Common Structural Rules employed advanced buckling strength method to calculate buckling ultimate capacity, considering the influence of initial deflection, and may calculate by using PULS program. The CSR formula was compared with some experienced formula and nonlinear finite element analysis, and some suggestions were put forward. At the same time, some research were also made on the influence of dent on the plate ultimate capacity, using nonlinear finite element method to calculate ultimate capacity, and using curve fitting method to achieve the discount coefficient of ultimate capacity of the plate with dent in. The fitting formulae were provided for the dent plate ultimate capacity assessment. Finally, the paper taking 300,000 ton tanker for example, according to the requirement of JTP Rules, caculates the buckling strength of unstiffened panels by advanced buckling strength assessment method and the ultimate capacity of stiffened panels considering loading redistribute. At last, some useful conclusions are concluded. |
