Research On Design Of Effective Superstructure Concerning Its Effectiveness

Effective superstructure is usually designed with full effectiveness according to current regulations, which causes strength excess and material waste. For rational design, taking effectiveness into consideration, this thesis aims to research the design of superstructure with lower weight on the basis of equal strength, fulfilling reasonable distribution of material. A basic design procedure of effective superstructure is put forward.Effectiveness is the key to superstructure design and appropriate definition of effectiveness can provide great reference. Mutual conversion relation of three effectiveness definitions is derived in this thesis, pointing out that the area reduction factor should be adopted as the definition of effectiveness for design. Formula from Lloyd’s Register regulation and Ю. А.Шиманский can both be used for approximate calculation of effectiveness at initial stage of design. The latter formula is derived from superstructure strength theory and is appropriately simplified according to the characteristics of effective superstructure. The result acquired by the formula proves high precision.The effective superstructure design is based on principle of equal strength, which assures the strength of superstructure equals that of main hull without superstructure. Several conclusions can be reached through theoretical derivation: smaller area of superstructure is needed to maintain the same strength considering its effectiveness. Only in central part of superstructure can the adjustment of material of both upper deck and the superstructure reduce the structure weight.This thesis takes a ship as an example to conduct the design of effective superstructure and the design method can be developed from one tier to multiple tiers. The design of mid-ship section should be conducted in priority, providing reference for other sections. Besides, whole ship finite element method can be adopted at final stage of design. Accurate results can be obtained, which can provide reference for the determination of final design.The design of effective superstructure should also focus on stress concentration, which may appear on the end wall, door opening of side wall and side wall end. Proper measures for reinforcement should be taken to reduce stress concentration according to regulations.