The response of a combined dynamic system consisting of a Spar, a mooring line system, and top tension risers is presented. The top tension of a riser is provided by a buoyancy-can that is laterally supported by a preloaded compliant guide. The overall system is nonlinear due to the mooring line restoring force, the friction between the buoyancy-cans and the compliant guides, and the friction between the risers and the guides at the Spar keel. The friction between the Spar and the riser system is captured by a Coulomb model, whereas the stiffness of the mooring line system is accounted for by using a nonlinear regression analysis of pertinent load versus displacement data. The combined model is numerically integrated using input time histories of force and moment that are compatible with a random representation (Jonswap spectrum) of a typical extreme environmental loading in the Gulf of Mexico. The input time histories of the force and the moment for the combined model are obtained at the center of gravity of the Spar by using a standard motion analysis program (MLTSIM). The numerical results of the time domain analysis of the combined model, in conjunction with ergodicity, are used for an associated Monte Carlo study. The Monte Carlo study provides useful information regarding the probability densities and the power spectra of various response components of the combined system. These results serve as a benchmark for additional analytical studies that call attention to the potential usefulness of the technique of statistical linearization for efficient dynamic analyses of preliminary design decisions regarding the combined Spar–Risers–Mooring lines system.
Coupled Analysis of a Spar Structure: Monte Carlo and Statistical Linearization Solutions
Contributed by the OOAE Division for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received January 8, 2004; final revision, November 5, 2004. Review conducted by: S. Yim.
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Spanos, P. D., Ghosh, R., Finn, L. D., and Halkyard, J. (March 23, 2005). "Coupled Analysis of a Spar Structure: Monte Carlo and Statistical Linearization Solutions ." ASME. J. Offshore Mech. Arct. Eng. February 2005; 127(1): 11–16. https://doi.org/10.1115/1.1862253
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