| The 800t lifting Jack-up in the design process is the unit of the largest crane capacity in China. The main function of it is to lift offshore wind turbine devices, bridge blocks, and other offshore structures. The design of the unit is the first case in our country, and represents the most advanced level of lifting platform in China. Since there is scarce research material about this kind of Jack-up published aboard and the domestic study just started, it is hard to have a deep understanding on its mechanical characteristics, wholly master its structural feature and find potential hazard, which make it difficult to ensure the safety of the Jack-up, and hinder the development of civil marine lifting equipment.This paper focuses on the study of structural strength of 800t lifting Jack-up in elevated conditions. The research will fill up the blank of strength analysis of large lifting Jack-up in civil circumstance, provide relevant technology and reference, and contribute to the development of our new offshore equipment. The study results can also be extended to the wind farm installation vessel. It provides references to our design of large wind farm installation vessel.In this paper, the basic analysis method of such kind of platform is firstly determined, the analysis process is set down, and contents and strength criteria are summarized. Then the theories and calculation methods of environmental loads are discussed, the FE model of 800t lifting Jack-up is built and the key techniques of FEA method is studied. Finally, the finite element calculation is carried out, the results is analyzed and checked by ABS rules and suggestion for modification is given. The main conclusion of analysis in this paper is described below:(1) The most severest condition happen in severe storm condition (loading 100%, wave direction 90o) and in ultimate operation condition (arm 120o, wave direction 90o);(2) The structures of leg, hull, leg well, crane support structure and spud can are complied with ABS rules, but the leg well and crane support structure are suggested to be enhanced in order to improve the safety of unit;(3) The anti-overturning stability of the Jack-up in severe storm condition is quiet well. |
