The Dynamic Response Analysis Method And Experiment Study Of Offshore Structure With Non-Initial Conditions

Compared with land structure, offshore structures are inclined to be destroyed under the complex environment, so dynamic analysis is necessary for offshore structure. The dynamic analysis approach of offshore structure includes time-domain method and frequency-domain method. While the time-domain method is inefficient, and the traditional frequency-domain method cannot consider the initial conditions, only can get the steady response of the structure system. Take the disadvantage of the traditional frequency-domain and research result of scholars at home and abroad,this paper aimed at studing a dynamic response analysis theory of fixed offshore structure with non-zero initial conditions in the frequency-domain.Aim at the problems of traditional dynamic analysis approach in the frequency-domain, this paper has carried out the following research:(1)Has written a program of dynamic response in the time-domain and in the frequency-domain with non-zero initial conditions according to the research result of scholars at home and abroad.(2) Selected a monopile of offshore wind turbine, calculated the dynamic response of the monopile with non-zero initial conditions used proposed algorithm and time-domain algorithm, the results of proposed algorithm and time-domain algorithm are good agreement. Selected a jacket platform, calculated the dynamic response of the jacket platform with non-zero initial conditions used proposed algorithm and ANSYS,the results are good agreement except initial moment. The results of two numerical examples verify the accuracy of proposed algorithm.(3)Designed and produced a physical model of a jacket platform, divided the working conditions with non-zero initial displacement to test the dynamic response of the physical model.Then, calculated the dynamic response of corresponding working conditions of the physical model used proposed algorithm.The results of experiment and calculation have a good consistency. The experiment further validates the proposed algorithm can calculate the dynamic response of jacket platform with non-zero initial displacement.In this paper, author applied the proposed algorithm to the fixed offshore structure, While overcomed the disadvantage of traditional frequency-domain method. There are two innovative points:(1)Applied the theory of dynamic response with non-zero initial conditions in the frequency-domain to the offshore structure, the result of proposed algorithm is coincident with time-domain’s.And the proposed algorithm provided theoretic support for the calculation of the offshore structure with non-zero initial conditions. (2) Designed and operated a corresponding physical model test, the result of experiment is coincident with the result of proposed algorithm. This experiment verified the accuracy of the proposed algorithm in calculation of the fixed offshore structure.In conclusion, this paper applied the proposed theory of the dynamic analysis in the frequency-domain to the offshore structure, provide the theoretic support for the calculation of the offshore structure with non-zero initial conditions of the fixed offshore structure joints.