A new method for determining the design values of wave-induced vertical bending moments acting on ship-shaped offshore installations in survival conditions

Abstract

The aim of this study is to develop a new method for determining the design values of wave-induced vertical bending moments acting on ship-shaped offshore installations in survival conditions. Although the guidelines of classification societies are useful for determining the design values, considering survival conditions with the most probable extreme waves for a return period of 100 years, the determination of their design values is not straightforward owing to the complex procedures and a large amount of hydrodynamic analyses which require significant computation time. In this paper, a new method is developed to determine the design values of wave-induced vertical bending moments for ship-shaped offshore installations in survival conditions. As an applied example, a very large crude oil carrier (VLCC)-class floating, production, storage, and offloading (FPSO) unit in survival conditions are considered at six different seas. A comparison is made among the present solutions, environmental contour-based solutions, and the long-term stochastic method-based classification society rule values.