As the development of offshore oil well advances to deep sea, the platform/mooring lines coupled analysis in time-domain is required in estimating the design tension to consider the complex nonlinear effects in the dynamic responses of floating offshore structures. However, in the early design stage where a number of environmental conditions are dealt with, a simpler analysis method adopting the uncoupled and quasi-static analysis is still practical. In this study, the uncoupled, quasi-static analysis in frequencydomain and the coupled analysis in time-domain were compared to establish a basis of design analysis flow from former to latter. A semi-submersible platform was selected as a comparison model, and a reasonable agreement between the two analysis methods were identified.

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