Fatigue Damage Analysis of Offshore Structures using Hot-Spot stress and Notch Strain Approaches

In offshore structures, the consecutive environmental and operational loading lead to an ever-changing stress state in the topside structure as well as in the substructure, which for offshore jacket-type platforms (called of fixed offshore structures) commonly used, result in fatigue damage accumulation. A wide variety of codes and recommended practices provide approaches in order to estimate the fatigue damage in design phase and remaining life in existing structures. In this research work, fatigue damage accumulation analyses applied to an offshore jacket-type platform using hot-spot stress and notch strain approaches are presented. These analyses are performed using wave information from the scatter diagram collected in North Sea. The wave loads used in this analysis were obtained using the Stokes 5th order wave theory and Morrison formula. The jacket-type offshore structure under consideration has a total height of 140.3 meters, a geometry at mudline of 60×80 meters and composed by tubular elements.