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The fixed jacket isstill the most common offshore structure used for drilling and oil production.The structure consists of tubular members interconnected to form athree-dimensional space frame, which can be categorized into a columnstructure. The structure usually has four to eight legs that are battered toachieve stability against axial compressive loads and toppling due to waveloads. The configuration of a typical member on the jacket structure hassignificant influence on buckling and fatigue strength. Horizontal and diagonalbraces play an important role in resisting the axial compression and wave loadon the global structure. Thispaper discusses the effect of symmetrical and asymmetrical configuration shapesin buckling and fatigue strength analysis on two types of fixed jacket offshoreplatforms. The axial compressive and lateral (wave) loads were considered andapplied to both structures. The material and dimensions of the two structureswere assumed to be constant and homogenous. Crack extension and corrosion werenot considered. To assess the buckling and fatigue strength of thesestructures, due to the symmetrical and asymmetrical configuration shape, thefinite element method (FEM) was adopted. Buckling analysis was performed onthese structures by taking two-dimensional planes into consideration to obtainthe critical buckling load for the local plane; fatigue life analysis was thencalculated to produce the fatigue life of those structures. The result obtainedby FEM was compared with the analytical solution for the critical bucklingload. The stress-strain curve was also applied to show the difference betweensymmetrical and asymmetrical shapes. For fatigue life analysis, the procedureof the response amplitude operator was applied. |
