OPTIMAL FATIGUE DESIGN OF OFFSHORE STRUCTURES

The fatigue limit state is one of the criteria for the dimensioning of offshore structures. Fatigue life prediction of structural members is subject to uncertainties which require the use of reliability engineering methods, which can be used to optimise inspection plans. Reliability updating after results of previous inspections is discussed for some selected examples. Trade-off studies with respect to accepting in service inspections and repair or alternatively improve the design are illustrated. For the considered structures it is also demonstrated how the results from these rather advanced calculations can be represented in the simplest design format, i.e. optimum fatigue life using traditional fatigue analysis.