In order to enhance the reliability of the offshore platform foundation subjected to wave and seismic forces, it is very important to clarify the dynamic response properties due to these forces with uncertainties. In the present study, the MCS (Monte Carlo Simulation) approach is applied to evaluate the uncertainty effects on the maximum response quantities of an idealized 3-dimensional offshore platform with foundation. The MCS method can be efficiently applied to the response evaluations of the offshore platform with pile foundation system with uncertainties. It is shown that since the uncertain parameters play important contributions on the maximum response evaluations, it is essential to estimate the effects on uncertainties to responses for the reliable design of the offshore platform with foundation.
For the offshore structure subjected to dynamic forces, the dynamic response is usually carried out with the time domain analysis and spectrum analysis. While the most important dynamic force is given by the wave force, it is essential to clarify the combined contribution on the seismic force for the offshore structure located in seismic active area. An effective method should be provided by the random vibration approach on the response evaluations of the offshore structure subjected to dynamic forces with random properties. It is shown that the characteristics of the structure and external forces have usually uncertainties on the response evaluations. In order to implement the reliable design of the offshore structure, it is important to clarify the effects on the uncertainties to the maximum response estimation.
If the response estimation to uncertainties of the external forces are represented with the random vibration approach, it is suggested that the second moment approach can provide an effective method for the response evaluation (Kawano et al(2001)).