A first step in quantifying the value of OMA based fatigue stress estimation

To facilitate the modelling of the fatigue life of an offshore structure, a methodology based on the Operational Modal Analysis (OMA) is proposed. The idea is to utilize monitoring results as a means to reduce uncertainties associated with structural responses and to take benefit of this information to optimize assets integrity management. In the present work a scaled model of a structure is considered for which the displacements are measured under random excitation. The strains at any point of the model structure are estimated based on OMA and the accuracy is assessed and verified by comparing the estimates with strain gauge measurements. The obtained strains are used to evaluate the equivalent stress range, which is further used to compute fatigue failure probabilities as well as risk estimates. Obtaining information comes at a cost, which is quantified using value of information analysis. The value of information assessment is illustrated through a principal example.