Risk Assessment On “Pan Yu 30-1” Jacket Platform

“PanYu 30-1” jacket platform is located in the South China Sea,where the ocean condition is extremely adverse.Besides,the structure of jacket platform is large and complicated,with lots of members and joints.Therefore it is of vital importance to make risk assessment for security service.Firstly,this thesis conducts static analysis on “Pan Yu 30-1” jacket platform under extreme ocean condition.Weibull distribution is adopted to match the design wave parameters of 100-year-return,regarded as the analysis environment combined with wind and current of 100-year-return,under which the static analysis of platform and piles are conducted respectively.According to the analysis results,stress and displacement of topside and piles are analyzed,as well as the member code check and joint code check of jacket,so as to perform an overall security assessment for the platform under extreme ocean condition.Researches show that all the structural mechanical properties meet the safety requirements.Secondly,dynamic characteristics analysis of “Pan Yu 30-1” jacket platform under extreme ocean condition is performed through the transit analysis method in ANSYS.Natural vibration analysis is conducted firstly,to obtain that resonance between the structural natural periods and wave periods will not occur.On the base of it,transit analysis is conducted to obtain the stress and displacement time-history curve,so as to perform an overall security assessment for the platform dynamic characteristics under extreme ocean condition.Then,the fatigue damage of “Pan Yu 30-1” jacket platform under stochastic environment is analyzed through ANSYS.According to the sense of JONSWAP wave spectrum,the wave scatter diagram with eight headings is arranged as 3200 Airy waves to represent the sea state,Stress time-history curves of nine represent points are plotted through the transit method,with the stress concentration factor of every one calculated through finite element method,hot stress time-history curves are obtained further,and the “Rain Flow” method is used to carry on the stress amplitude statistics.S-N curve of T type recommended by DNV standard is chosen,and according to the Miner Linear cumulative theory,annual fatigue damages of nine represent points are calculated,so as to perform an assessment for the platform fatigue life under operating condition.Ressults show that fatigue life of nine points meet the safety requirements.Besides,the thesis evaluates the items such as corrosion fatigue and strength reduction due to marine growth.It is found that corrosion will intensify fatigue,while marine growth will enlarge forces on structures.According to the conclusions,relevant solutions are put forward,and an effective project of “Real time Monitor” is proposed too.Finally,the thesis conducts risk assessment of ship berthing.Through analysis of berthing in front and by side,it is summarized that berthing by side is better;Comparing platform strength and equipments safety,the recommending Max.normal veolicity of berthing by side and berthing without fenders are given,which provides guidance for safe berthing.