Research On Wind-induced Vortex-induced Vibration Characteristics And Vibration Reduction Mechanism Of Jacket Platform

The development of marine resources has moved towards the deep sea,and more and more deep-water jacket platforms have also been put into use.This type of largescale deep-water jacket platform usually uses horizontal construction in the construction process.Due to problems such as the construction sequence,unilateral constraints often occur.At the same time,when a large deep-water platform is transported.Due to its large structure and long single pipe length,vortex-induced vibration will occur under the influence of wind load.Long-term vibration will cause structural fatigue damage and affect the service life of the platform.Based on this,this paper has carried out the research on wind-induced vortex-shedding vibration of jacket pipes under construction and transportation,and used nonlinear energy sinks to reduce vibration.The research of this article is mainly divided into two parts.The first part is to analyze the vibration reduction research of rigid cylindrical vortex-induced vibration.This part aims to analyze the vibration reduction characteristics of non-linear energy sink for such circular-section members with vortex-induced vibration.A two-degreeof-freedom master-slave system motion equation is established,and the approximate analytical solution of the multi-scale mixed harmonic balance method is used to solve the problem.The numerical results are compared to verify the correctness of the method and the derivation process.The amplitude-frequency response curve of the system is obtained,and the sensitivity analysis of different nonlinear energy sink parameters is performed.At the same time,it is also found that after adding a nonlinear energy sink,the system has saddle junction bifurcation and Hopf bifurcation,which have obvious nonlinear phenomena.In the second part,the dynamic equations of unilateral constraint and simply supported single pipe are established,using the Euler beam theory,attaching a nonlinear energy sink,and simulating the fluid force received by the wake oscillator model.The vortex-induced vibration prediction of the jacket pipe is combined with the particle swarm optimization(PSO)method to optimize the parameters of the nonlinear energy sink.The optimized nonlinear energy sink can effectively reduce the motion response of the vortex-induced vibration pipe.Finally,the influence of the non-linear energy sink layout position and parameter deviation from the design value on the vibration reduction effect is analyzed.