Study On Progressive Collapse Analysis Methods Of Ultimate Strength Of Ship Structures

The ultimate strength analysis of ship structures which can account for the post-buckling behaviors of ship structures is an essential part of strength analysis of ship, being able to show the true reserved strength. The collapse of a ship hull is a progressive procedure. After some of the structural components reach their buckling strength, the hull can still work until the whole hull reaches its ultimate strength. Compared to other methods, progressive collapse analysis method represented by Smith's method and nonlinear finite element method (NFEM) is an efficient, accurate, reliable method which has been widely adopted in practice. In this article, the application of Smith's method and NFEM in the progressive collapse analysis of ultimate strength of ship structures is researched.The contents of this article are as follows:1) Discussed the basic theory of progressive collapse analysis of ultimate strength of ship, and the present development of this art. The design principles and technical requirements for the ultimate states were discussed;2) Introduced the ultimate strength analysis method of ship structures based on collapse modes, studied the influence of imperfection such as initial deflection, residual stress on the ultimate strength of ship structures;3) Studied the stress-strain relationship derived from analytical method considering the effect of lateral load, resulting in a more accurate stress-strain curve;4) Compiled two different analysis programs based on the CSR and on the method in 7) respectively. The programs were applied to the progressive collapse analysis of ultimate strength of box girder and ship girder, and the results were compared;5) The origin of the nonlinearity of ship structures was discussed, the method and procedure of the application of NFEM to the ultimate strength analysis is introduced;6) The ultimate strength of plates, panels, box girder and ship girder in different load conditions are analyzed. The effect of lateral load on the ultimate strength of ship structures was discussed.