Development of a model for the optimal determination of the deck elevation of offshore platforms

In the present paper, a reliability-based cost-benefit model for the optimal determination of the deck elevation for new offshore platforms is proposed. The assessment of the benefit of reduced risks and the costs of increasing the deck elevation are weighed. If the deck elevation is increased, the risk associated with the wave forces on deck is reduced, because is less the probability of wave forces on deck; however the significant cost of increasing the deck elevation is magnified by the cost of mobilization of equipment in the life of platform, it cost is increased because boats with more capacity are required (in general, the rent is more expensive). For the propose of assessment the risk associated with the wave forces on deck a probabilistic model for the future maximum wave heights under the platform is studied taking in account the location of the platform. In addition, the expected cost of mobilization of equipment and the expected cost of maintenance of the structure and equipment after of the hurricanes futures are estimated, and then the expected life-cycle cost of the platform is determined. One example of application is proposed, where several elevations for the deck are studied and their corresponding life-cycle costs are estimated. The optimal deck elevation is chosen so that the expected life-cycle cost is minimized.