Modelling of Waves for the Design of Offshore Structures

For the design of structures we need to select design safety levels to ensure structures shall safely operate and not collapse. These levels are given in relevant safety standards. For these levels we need to identify the actions and ensure that we design according to recognized codes. The objective of this technical note is to shed light on the identification of the design action due to waves to ensure that the design action events be incorporated in the design phase of the structures. The approach used in this technical note is to give a description of an actual extreme event, discuss the efforts and research that was undertaken to explain the event, investigate wave conditions which possibly could have been present at the day of the event, and present a challenge and suggestion for wave tanks to ensure that design action events really are identified during wave tank experiments. We will, in particular, discuss the need for modelling of nonlinear waves to ensure that the action effects from waves are properly identified.