Weight Control Analysis And Jacket Strength Verification For CEPN Jacket Platform In Bohai Bay

The topside weight of a Bohai bay platform CEPN is over 10,000 ton,exceeds the hoist capability of Lanjing,which is the biggest float crane of COOEC.Hence,the topside of CEPN needs to split apart for construction and installation.During the overall development plan design phase,the split scheme is to divide the topside in two.After reviewing the topside spilt scheme during basic design phase,the designers find that the east topside has a severe eccentricity.Besides,the east topside is too heavy to meet the lifting requirement of Lanjing.Due to high sensitivity of the weight and C.O.G(center of gravity)of CEPN topside,the CEPN executes rank A weight control method.The designers study split scheme optimation of CEPN topside first.After contrasting different topside split scheme,the designers still take the two pieces scheme,optimize the original one.They adjust the split line from the middle of 2 and 3 axis to a little close to 3 axis,set temporary supports to increase the distance between the hanging points.As a result,the severe eccentricity problem of the east topside is solved.After the split scheme optimization of the CEPN topside,the lift weight of east and west topside still exceed Lanjing's hoist capability,and the center of gravity also need to be adjusted.In this situation,each profession takes weight reduction measures for the topside.The designers utilize SACS software to proceed 3D modeling,precisely simulate the weight and center of gravity parameter for the topside.After 15 times weight parameter adjustment,5 times center of gravity parameter adjustment,the east and west topside's weight and center of gravity finally meet the hoisting demand of Lanjing.On this basis,take static analysis and strength check for CEPN to check the rationality of the structure scheme.For the limitation of thesis,this paper only focus on the jacket and pile' static analysis and strength check.Utilizing SACS software to model the structure of the CEPN,simulate the functional load and environmental load of CEPN jacket,combine these basic loads and get 80 possible load combinations,analog 80 load combinations to the jacket,computes member strain and stress value for each structure member.Through analyzing member UC,member joints UC,member joints strength UC,member deflection,pile safety factors,adding stiffeners to the 7 joints which fail to meet the requirement of member joints strength UC,the result shows that the CEPN jacket and pile have enough strength to meet all kinds of load conditions while the platform is at in-place status.Through weight control and static analysis,the designers can get optimal structural design scheme,which provides safety guarantee for CEPN topside' construction,installation and in-place operation.