Assessing the Impact of Climate Change on the Fatigue Life of Offshore Structures

Abstract

Design life of offshore structures is in general in the 20- to 30-year range, with some cases going up to 50 years. Fatigue is one of the major design criteria for such structures. Climate change may affect the fatigue life of offshore structures, it would be necessary to update the design procedures to take into account climate change effects on structural performance. This paper aims to investigate the impact of climate change in the long-term fatigue life of offshore structures due to wave loading. For this purpose, available environmental conditions for two locations (South East Brazilian Coast and North Atlantic Ocean) generated by the HadGEM-2S global climate model, considering representative concentration pathway (RCP) 4.5 and RCP 8.5 future scenarios and the historical (past) scenarios are considered. The assessment in both locations is performed for two structural models: an idealized stress spectrum for a generic fatigue hot-spot and a steel lazy wave riser (SLWR) connected to a floating production storage and offloading (FPSO). Fatigue life is estimated using the S–N curve approach. Results show that the impact on the fatigue life depends on the structure dynamic characteristics, on the geographic location and mainly on the greenhouse emission scenario. In general, for the Brazilian location, when compared to the historical scenario, most of the future scenarios lead to slightly higher fatigue damages (lower fatigue lives). On the other hand, for the North Atlantic location, there is not a clear trend for future climate change scenarios.