Study On The Structural Strength Assessment Of An 800t Crane Jackup In Floating Condition

The 800t crane jackup is intended for lifting offshore wind tubine devices, bridge blocks, offshore platform equipment and so on. With the conbination of the merits of both traditional self-elevating platforms and crane vessels, it can work in floating condition as well as in standing state, which is a newly-designed function featuring the first time domestically.This paper focuses on the study of hydrodynamic and structural strength characters of the crane jackup in its floating condition, which is the design lightspot of the platform. In this work mode, the platform possesses good static stability, strong crane capacity, full circle swing boom and large range of operating water depth so as to obtain easy operation and save work time. However, the platfrom in floating condition has different features in motion and load effect from self-elevating platforms and crane vessels, and the research on it is rare currently. Therefore, it is meaningful and necessary to study on the issue and get more knowledge about it in order to ensure its operation safety and offer suggestions in further design and research.In this paper, the hydrodynamic and finite element models of the crane jackup in floating condition are created with key modeling techniques introduced in detail. The 3-D flow theory is emplyed here to conduct the hydrodynaic analysis with the effects of parameter changes discussed. After that, the external load is appled on the structural model for FE analysis. Finally, the assessment of structural strength and buckling is made as per the ABS rules and corresponding advices are proposed for improvement. The main results of this paper are as follows.(1) Study the modeling techniques of deck loads, liquid tank loads and the connection between legs and the main hull.(2) Motion and load responses of the crane jackup in its floating condition are calculated for rule check of structural strength and buckling as well as improvement suggestions.(3) The theoretical and numeric methods are used to investigated the impacts of water depth and leg length underwater on motion and load effects.(4) The FE analysis and rule check of the plaform in transit condition a made and results show the leg structure has enougth stregnth. The research results of this paper can be heplful for increasing the kowledge of the crane jackup in floating condition and improving its design and optimization.