Guyed tower response to irregular waves considering linear and nonlinear mooring cables

Wishahy, Momen Abdel-Magid (1982) Guyed tower response to irregular waves considering linear and nonlinear mooring cables. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (13MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The study presents the dynamic analysis procedure for predicting the guyed tower response to irregular waves. Hydrodynamic interaction is taken into account by the added water mass concept and the fundamental frequencies are determined using i) a lumped parameter two dimensional beam model and ii) three dimensional truss finite element model. Effect of the mooring guylines is simulated using one dimensional boundary elements. The example structure analyzed is the Exxon test guyed tower erected in 89.3 m deep water in the Gulf of Mexico. The measured wave height-time history reported by Exxon is used to determine the wave forces. Irregular wave forces are computed using linearized Morison's equation. The nonlinearity of the mooring system is considered using NONSAP finite element program. The tower response in terms of offset-time history to wave forces is determined for both linear and nonlinear cable behaviour. Numerical results obtained in this investigation are within the maximum values accepted by current design criteria. The computed frequencies and the responses agree reasonably well with the available measured values.

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