Abstract
This paper is concerned with a methodology for defining metocean criteria for the analysis of subsea pipelines. The approach that has been developed incorporates the statistical dependence between wave and current loading. The method achieves this through a combination of the application of the conditional extreme value model of Heffernan and Tawn (2004) and clustering algorithms. This is particularly important in regions where the currents are largely wind driven as there can be a strong correlation between the two. The results can be used to assess fatigue damage from vortex-induced-vibrations and wave loading. The same model can be used to derive deterministic design events. The method is applied to a pipeline in the Caspian Sea. The results are compared to models that assume either independence or a perfect correlation between waves and currents. It is shown that simpler models that do not accurately model the dependence between the waves and the currents can provide estimates of fatigue damage that are an order of magnitude too high or too low.
