An experimental and numerical study on jack-up dynamic behavior

This paper presents the more salient results of an experimental and numerical study on jack-up dynamic behavior. The laboratory studies of three principle jack-up platform models were carried out in both regular and irregular waves. The data from irregular wave tests were analyzed in both the probability domain and frequency domain supported by a careful error analysis. Computer simulations were carried out in the time domain using a nonlinear, dynamic, multiple degree of freedom software which includes various hydrodynamic interaction options. The experimental results and associated computer simulations demonstrate that nonlinearities are important even with the present simplified model testing and different nonlinearities have different (sometimes compensating) influences on the structure's dynamic behavior. Some more specific results include: (1) The stiffness obtained from static tests can be significantly lower than that inferred from dynamic vibration tests; (2) relative motions from structural compliance are such that they cannot be responsibly neglected in the hydrodynamic computation; and (3) inclusion of the P-O effect in the structural schematization is essential for the jack-up simulations.Offshore TechnologyCivil Engineering and Geoscience