Research On The Structure And Fatigue Analysis Of The Jack-up Platform Based On SESAM Software

At present Jack-up is the most popular drilling equipment among the various platforms in offshore oil exploration in China.As one of the movable offshore drilling equipment,it would always work in the tough ocean environment and suffer the wave,current and wind load,which inevitably cause the structural damage and affect the operation safety of the platform. In addition,most of the environmental loads are random, so it will cause the stresses varying with time on the legs of the platform. The variation stresses may make the legs suffered the fatigue damage and threaten the security of the entire platform.In order to ensure the effectiveness of the structure, it needs to performe the structure analysis to make sure that the platform has enough strength reserve in case of the extreme load and assess the fatigue life of the legs to avoid the failure of the structure.In a word,it is very necessary and meaningful to carry out the structure and fatigue analysis.SESAM software is the most professional one among the various softwares that can be used for structure analysis and fatigue analysis.It is developed in the case that the finite element technology is widely used in naval and ocean engineering.SESAM is very suitable for the Jack-up platform and other offshore structures because of the professional and complete function.But at present there is a lack of systematic learning materials.In this paper,the basic function and operation of relevant SESAM modulars are summaried systematically for the first time and the structure and fatigue analysis procedure based on SESAM software are established for the offshore platform. Then the theories of the structure and fatigue analysis in SESAM are studied in depth.All the studies mentioned above would provide certain reference for the later learners and favored the popularization and application of SESAM software.Furthermore,structural strength analysis and spectrum-based fatigue life assessment are performed for a jack-up platform based on SESAM software,and the results show that the structure and fatigue strength both meet the requirement.Finally,the sensitive analysis is carried out for the key factors that need to be selected,such as S-N curve,wave spectrum,different gamma parameters of JONSWAP spectrum and wave scatter diagram.The results obtained may provide reference on how to select these factors and be helpful to perform fatigue anslysis in future. From this work it can be seen that SESAM software is convenient and qicuk in the structure anslysis and fatigue life assessment,so it is suggested to be used widely in ocean engineering.