Research On TLD Vibration Reduction Of Jacket Platform Under Wave Load

Jacket platform is widely used in offshore platform because of its simple form,convenient design and processing.Due to the long-term complex and changeable Marine environment,the offshore platform of jacket will inevitably suffer long-term effects of wave load.However,there is still no systematic research on the vibration reduction effect of jacket offshore platform under wave load.In view of this,the wave load characteristics in the Marine environment and the vibration reduction effect of the liquid damper(TLD)set on the jacket platform under the ocean wave load are systematically studied in this paper.Firstly,based on Stokes second-order wave theory and Morison equation,the effects of wave period,wave height,water depth and other factors on wave load was studied.Wave fields and cylindrical structures were established by Fluent,a fluid engineering analysis software,and the influences of Keulegan-carpenter number and Reynolds number on the values of drag force coefficient and inertia force coefficient were analyzed.When Kc<5 and the value is 1.57,with the increase of Re,Cm changes between 1.5 and 2.5,while Cd is stable around 0.2.When 5<Kc<25 and the value is 6.30,with the increase of Re,Cd changes between 0.6 and 0.8,and Cm changes between 2.0 and 2.5.When Kc>25 and the value is set at 26.20 and 27.00 respectively,with the increase of Re,Cd values between 1.00 and 1.30,while Cm is stable at about 2.0.Secondly,the influence of frequency ratio,mass ratio,form and quantity of water tank and characteristics of regular wave load on TLD vibration reduction of jacket platform is studied by combining the smooth particle hydrodynamics(SPH)method with finite element method.The results show that when the ratio of wave load frequency to structural natural frequency is 0.5,the set frequency ratio is 1 and the mass ratio is 3%.The structure of the platform with three shock absorber tanks has the best vibration reduction effect,and the vibration reduction rates of horizontal displacement and horizontal acceleration at the top of the platform are more than 38%.When the jacket platform is subjected to irregular wave action,the three water tanks with 30% frequency bandwidth have the best vibration reduction effect.Finally,aiming at the actual project,the influence of design parameters such as the quality of the jacket platform upper equipment and the diameter of the main pipe on the vibration reduction effect of TLD is analyzed.When the quality of the upper equipment of the platform is 1000 tons and the diameter of the main pipe is 1.40 meters,the vibration reduction effect of the jacket platform is the best.Under the action of different seismic waves,the dynamic response of the platform with TLD is analyzed.The results show that TLD has good vibration reduction effect for seismic action.