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Ass. Lect. Amr Ramdan Ibrahim Ali Elgamal :: Theses :

Title DYNAMIC BEHAVIOR OF TENSION LEG PLATFORMS SUBJECTED TO HYDRODYNAMIC FORCES
Type MSc
Supervisors Ashraf M. Abou-Rayan, Ayman A. Seleemah
Year 2011
Abstract Among compliant platforms, the tension leg platform (TLP) is a hybrid structure which is generally used for deep water oil exploration. With respect to the horizontal degrees of freedom, it is compliant and behaves like a floating structure moored by vertical tubular members or “tethers”. These tethers are pretensioned due to the excess buoyancy of the platform, whereas with respect to the vertical degrees of freedom, it is stiff and resembles a fixed structure and is not allowed to float freely. Dynamic analysis of squared and triangular TLP models under regular waves is presented, considering the coupling between surge, sway, heave, roll, pitch and yaw degrees of freedom. The analysis considers various nonlinearities produced due to change in the tether tension and nonlinear hydrodynamic drag force. The wave forces on the elements of the structure are calculated using Airy’s wave theory with Chakrabarti (1971) approaches and Morison’s equation, ignoring the diffraction effects. The nonlinear equation of motion is solved in the time domain using Newmark’s beta integration scheme. Numerical studies are carried out in the time domain to examine the effect of change of wave parameters (wave height and wave period) and coupling effect in dynamic response of a square and a triangular TLP under a unidirectional surge wave force. Also, Numerical studies are conducted to compare the coupled response of a triangular TLP with that of a squared TLP and the effects of different parameters that influence these responses are then investigated. Computer MATLAB program is developed in this work for nonlinear dynamic analysis for both triangle and squared TLP. The program is capable of solving large displacement problem dynamically in the time domain.
Keywords TLP, Offshore Structures, Compliant Structures
University Benha University
Country Egypt
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