Structure Strength Evaluation And Fatigue Strength Assessment Of Semi-submersible

The Semi-submersible platform is one of the best equipment for oil and gas development, also for the purpose of "the construction of marine power". It is necessary to evaluate the structure strength and fatigue strength of Semi-submersible platform in order to ensure its security.The aim of the paper is to make an assessment for the safety of Semi-submersible platform, which divided into three parts: the wave load forecasting, the structural strength, the fatigue strength. The main contents are as follows:1) The wave load prediction research of the Semi-submersible platform is calculated using the hydrodynamic analysis software--SESAM.First it can calculate the movement responds with different incident frequency and wave. Then take the vertical wave bending moment and torque as the Dominant Loading Parameter, and take a long-term prediction of wave loads. In the last, the wave height, wavelength and phase values of design wave.2) With the help of software MSC.Patran / Nastran, we can establish the overall finite element model of the semi-submersible platform. After that he overall structural strength assessment is calculated by the design wave method.3) Based on the structure strength results, select the fatigue joints and detailing the model. The fatigue strength of the semi-submersible platform is carried out with the spectral analysis based on the S-N curve and Miner linear cumulative damage theory.In summary, this paper can provide some reference and a reasonable solution for the strength assessment of future semi-submersible platform.