Study On Design Wave Method Of Global Strength Assessment Of A Deep-Water Semi-Submersible Platform

Deep-water semi-submersible platform always operates in a complex marine environment.It is necessary to carry out global strength assessment of the platform to ensure structural safety early in its design process.At present,the design wave method is often adopted for the global strength evaluation of semi-submersible platforms.According to the relevant requirements of the code,the appropriate wave load conditions are selected.Based on the three-dimensional potential flow theory,the hydrodynamic prediction and structural response calculation are carried out with the design wave method.In this paper,the design wave conditions are studied on the basis of standards,and the results of spectral analysis and design wave method are compared to verify,so as to determine the reasonable design wave analysis method and the selection principle of wave load conditions.1.The key techniques involved in the global strength evaluation of semi-submersible platforms are summarized.Wave theory,design wave method and spectral analysis method are introduced respectively,and the global strength analysis process based on the above methods is proposed.2.The calculation model of the target platform is established,and the global strength of the platform is calculated by three different tank modeling methods,to analyze the influence of tank modeling methods on global strength evaluation of the semi-submersible platform.3.Based on the design wave method,the global strength of the platform is calculated after adding some new wave conditions.The hydrodynamic load characteristics and the stress level of key regions of the platform under different wave conditions are analyzed,to obtain control wave load conditions of key regions of the platform.4.The spectral-based global strength evaluation of semi-submersible platforms is proposed,and the maneuverability of the spectral analysis method is verified.The correlation between the spectral analysis method and the design wave method is explored by comparing the structural stress in the key connection area of the platform calculated by two methods,which provides a reference for determining the wave conditions of the design wave method.