The performance based evaluation of an idealized three dimensional model of the offshore platform subjected to wave and seismic force is carried out using the MCS (Monte Carlo Simulation) approach in the present study. It is known that application of the reliability approach is very effective to estimate the response evaluation to not only the static forces but also the dynamic forces with uncertain situations. It is suggested that the reliability index determined by the MCS method to dynamic forces with considerably different characteristics plays the important roles on the available estimation of the performance based design on the offshore structure.
It is supposed that the reliable design of the offshore structure could be performed with the performance based evaluation. The dynamic forces such as the wave and seismic force include some uncertainties and it is important to examine the uncertainty effects on the dynamic response evaluation. Performing the elaborate evaluation of the dynamic response of the offshore structure, it is necessary to verify the uncertainty effects due to severe dynamic forces on the linear response situation as well as the nonlinear one. Many researches have been implemented to estimate the uncertainty effects on the design of the structure, especially to the land structure. Furthermore, it is suggested that the damage estimation plays important roles on the performance based evaluation with respect to dynamic forces. There are several available methods on the damage evaluations of the structure subjected to seismic motions (Fajfar, P, 1992, Park and Ang,1985). The strength demand spectrum is one of the most useful methods which can be treated with nonlinear effects on the structure subjected to seismic motions (Iemura,1998). It is supposed that the available damage evaluation could not be always carried outonly the strength demand response spectrum.