Statistical Investigation of the Nonlinear Behavior of Structures Operating Offshore

Due to the increasing amount of ship and offshore operations taking place in the ocean environment, the amount of reports concerning damage, loss of cargo or even loss of human lives increases, too. The reasons for these incidents have been a subject of intensive research for many years. Recently, the aim of some research concentrated on extreme wave phenomena such as ‘rogue waves’ or ‘the three sisters’. These phenomena are a severe danger, but they do not play a decisive role for most of the incidents happening at sea. More often, the reason for endangerment of structures in the environment is a fluid-structure-interaction that leads to unstable dynamical system behaviour. Including nonlinear effects in the calculations, through statistical investigation of structures in waves, it can be shown that critical behaviour of ships and structures can occur without the absolute necessity of heavy sea conditions or the occurrence of dangerous sea phenomena. The reason that many of these incidents do not lead to severe accidents lies in the experience of the master and his crew and their ability to change system parameters in a way that prevents the catastrophe. The aim of this paper is to show the current state of development of a program that uses a Monte-Carlo-Simulation technique based on a common panel-method for the creation of added masses and added damping with hydrodynamic coupling to predict the behaviour of the structure in several wave conditions.