The Research Of Safety Assessment Method For Jack-up Structures

Offshore structure is the basis for the development of marine oil and gas resources, and it is the sea life and production base. Now, in all offshore structures which are working, many platforms have been serving for many years. How to ensure their structural security has become an important issue.A jack-up as an example, this paper studies the structure safety assessment methods for the aging jack-up. Because of its complex structure, how to correctly simulate the real jack-up structure demands highly for the finite element modeling. This paper establishes the model database of the platform structure which is related to the finite element calculation. The database includes cabins tables,plated grillage tables,panel tables,plate tables,beam tables, as well as the related profiled bar tables. Besides,friendly interface is designed. Through the database, we can see that the platform cabin location, the plane location and its thickness, the beam location and its size. The thicknesses of plane and beam in the database can be changed in the friendly interface made by VB.In this paper, ANSYS is used to establish the whole finite element model of the platform. Besides, finite element structural attributes assigning and the model meshing are accomplished with the help of the database. According to load cases under different working conditions, the deformation and stress results are obtained. Then the structure safety analysis and evaluation can be achieved.The sizes and thicknesses of components can be modified and added conveniently under the help of the material database. The model is meshed accurately, owing to the combination of the material database and finite element software. The safety assessment of the jack-up in this paper are accomplished successfully, but the more important significance is that it provides references and guides for safety assessments of the similar complex structures.