Fatigue Load Reductions in Offshore Wind Turbine Monopile Foundations in Co-Located Wind-Wave Arrays

As offshore wind turbines (OWTs) increase in size and are placed farther offshore, hydrodynamic loads have increased contribution to total load, resulting in fatigue limit states becoming more important to consider in structural design. Previous literature shows that placing wave energy converters (WECs) peripherally to an OWT array results in a milder wave climate within the array. This reduction could affect the wave loads and fatigue damage of OWT support structures. In this exploratory study, the effect of peripherally-distributing WECs in front of a fixed-bottom OWT on the fatigue of the OWT monopile is investigated. Relative sea state reductions from WECs are quantified, and fully-coupled time-domain fatigue analyses are performed for a 10 MW reference OWT. Results indicate that both a single WEC and a WEC array can lead to up to 8% and 10% fatigue load reduction in unidirectional wave cases, respectively.