Response Analysis Of The TLP Under The Action Of Freak Waves

Based on the potential theory and by the use of New Wave theory, the extreme wave loads are calculated. This paper presents theoretical studies and numerical simulation on the TLP in time domain.First of all, several basic problems of "freak wave" are studied, including the history reports, definition and the cause of the occurrence. And then, the derivation of The New Wave theory is given, by applying the New Wave theory, a typical shape of extreme event module is constructed.Secondly, the frequency method are introduced. A higher order boundary element method is used to calculate the radiation of a truncated cylinder in open sea. The results are compared with the analytical results and WAMIT software to examine the numerical method. The good agreement between the numerical results and analytical solutions and WAMIT results prove the validity of the mathematical model presented in this paper.Thirdly, static and dynamic analysis are carried out to research the response of TLP under external loads. And the static analysis is the foundation of the dynamic analysis, providing necessary parameter relation for the construction design phase. According to the results, almost all the parameters are sensitive to the stiffness and pretension, which are of great importance in design phase. The dynamic analysis is studied through frequency method and time domain method. In time domain, in order to get the wave force used in time domain, the convolution between impulse response function and extreme wave profile should be calculated. The differential equation of platform motion is computed by the fourth order Runge-Kutta integrating method in the time domain. By comparing the results between the frequency domain and time domain of the truncated cylinder, time domain method is proved to be valid.Finally, the relation between the stiffness and natural vibration frequency of the TLP is studied. Further more, the influence of wave period and stiffness of TLP tethers are further studied. The conclusions will benefit practical engineering.