Analysis Methods Research For Flexible Components Of Offshore Structures

Mooring cables, risers and tension legs, etc, all belong to the flexible components of offshore structures based on their characteristic. To research analysis methods of these structures are very significant for reasonable design of the mooring system and ensuring the platforms working and safety. Therefore, the appropriate calculation methods for static analysis and dynamic response of the flexible components of offshore structures have been studied in this thesis, including analysis of couple calculation in time domain.Firstly, make further calculation of the catenary equation. A calculation model by connecting two segments of catenary equations has been developed to computing initial deformation of floating hawsers and mooring chains of the single point mooring system. According to the research, a program has been compiled that is suitable for calculating the initial position and pre-tension of flexible structures.Additionally, the nonlinear dynamic response of the flexible components has been studied and simulated. A three-dimensional elastic rod theory is adopted to research nonlinear finite element model of the large deformation of space three-dimensional flexible structures, as well as the time domain analysis.At last, the nonlinear coupled response of the floating structure and mooring system has been researched. The floating structure is modeled as rigid body with six degree of freedom, and the mooring line dynamics is modeled using rod theory and finite element method. The connections between mooring lines and platform are modeled as linear and rotational springs and dampers. The time-domain coupled analysis of the single point mooring system which is parked at Karachi port has been done using HARP program based on research results and reality oceanic conditions.