Reliable structural design techniques for a wide range of offshore plantstructures aimed at utilizing renewable energy and marine space as wellas developing marine resources such as drilling, production andcollection of oil, gas and mineral resources of the seabed are required.In order to secure the structural design techniques for the fixed offshoreplant structure, the jacket structure design method and strengthevaluation were carried out as initial studies. In this paper, the basicgeometry of the 20K-ton jacket was determined according to theclassification rules and general jacket design process. The diameter ofthe subsea penetration pile was determined in consideration of the sizeof the offshore platform and the installation depth. And the innerdiameter of the jacket leg was determined so that the condition of thesubsea penetration piles installation was satisfied. Brace design for theentire panel was performed considering structural safety of eachmember such as slenderness ratio, hydrostatic collapse, columnbuckling. Since the jacket structure designed by the rule scantlingmethod has to ensure stability from the external forces such as wind,wave, current and operating loads during its entire service life, thestructural analysis was performed to supplement the scantling of thejacket members. The environmental and dynamic loads were replacedwith equivalent loads and applied to the beam elements of the jacketstructure. It was confirmed that significant stress occurred at the upperpart of the jacket by the horizontal force due to the environmental loadsand the vertical force due to the topside platform gravity, and the safetyof the structure was evaluated by unity check of all the members. Thisjacket design process that includes rule scantling and structural analysisfor scantling supplement can be effective the total design cycle andincreasing the reliability of the final structure.
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