Research On The Bending Efficiency Of Superstructure Of Cruise To Hull Girder Strength

In recent years,the superstructure of cruise ship has become much huger to satisfy requests of passengers and provide more space for better services,therefore the evaluation of the cruise ship superstructure response to hull girder loads is getting more and more attention.However,a modern cruise ship includes many zones for accommodations,entertainment,relaxing and so on.Due to the complex space structures in the superstructure,openings in decks for atriums stairs and elevators,large window openings in the side shell,lack of continuous longitudinal bulkheads between the decks,etc.,it is difficult to assess the ship hull strength.In term of this problem,the bending efficiency of superstructure which represents the degree of contribution of superstructure to hull girder strength can predict the normal stress distribution of superstructure and provide the reference for optimum structural design.Actually,the finite element method is the best way to deal with problems with complex structure and local stress,but it takes too much time and manpower to build a whole ship finite element model.As for the analytical method,the type of the superstructure with multideck and lots of side openings like cruise is not taken into account specially and the analysis result will not be reasonable in some cases.So,in the present thesis,the bending efficiency of superstructure and the influence of different factors on bending efficiency are analyzed combining the theoretical analysis and numerical simulation.The main work is shown as follows: 1)The interaction of main hull and superstructure is studied based on the beam theory and the analytical method for bending efficiency of the superstructure is introduced 2)The structural response of a typical passenger ship under the longitudinal ending is analyzed by the numerical simulation.The normal stress distribution and bending efficiency of the superstructure are studied.Besides the influence of side openings is discussed by comparative analysis.3)The influence of factors such as the length of superstructure,the area of the deck openings,the area of side openings and the width of the superstructure are analyzed based on the idealized finite element model.And the tendency of the effect of different factors is studied.4)Based on above studies,the fitting functions is obtained according to the tendency of the influence on bending efficiency and the calculation method of bending efficiency is carried out.And the result calculated with the improved method coincides with the FEM result.According to the analysis of the influence of different factors on bending efficiency,the bending efficiency study about the superstructure with multi-deck and side openings has been improved and the reference is offered for the safety assessment.