Strength Assessment Method Research For Tubular Joints Of Semi-Submersible Platform

As one complex and weak component in semi-submersible platforms, the strength assessment of tubular joints is very necessary and valuable. At present, the content on the tubular joints assessment of every classification is general, many details are not clear. Combining Liuhua-FPS platform, the major purpose of this paper is to research the method of the yielding strength, ultimate strength and fatigue strength assessment of the tubular joints according to the ABS Rules. The main contents are as follows:1) Discuss the naissance, classification and structural feature of semi-submersible platform. The critical accidents are used to show the importance of the tubular joints strength assessment. Do contrast analysis of the two strength assessment of the tubular joints, namely local model method and embedded method, and analyze the practicability of the embedded method.2) Study the material on FE strength assessment of ABS offshore rules carefully and build the global FE model of the platform, then the structural stress will be calculated and analyzed.3) According to the ABS rules, assess the ultimate strength of tubular joints with the results above. Some critical problems will be studied, such as confirmation of the tubular joints and determination of the tubular joints type.4) Based on S-N curve of tubular joints, linear fatigue accumulative damage theory and hot stress method, the spectral method of the tubular joints fatigue strength assessment will be studied, and the tubular joints of the actual platform will be calculated and analyzed.