Dynamic Performance of Jacket-Type Offshore Wind Turbines Under Combined Wind, Wave and Earthquake Loads Considering Scour Effects

Abstract

Seabed scour-induced degradation of the pile–soil system, together with the coupled action of seismic, wind and wave loads, poses great challenges to the long-term service safety of jacket-type offshore wind turbines. In this study, an integrated structural numerical model is established with consideration of nonlinear pile–soil interaction. By coupling OpenFAST (Version 3.5.0) and OpenSees (Version 3.7.0), accurate wind and wave load generation and refined calculation of structural dynamic responses are achieved. Then, the dynamic performance of jacket-type offshore wind turbines under combined wind–wave–seismic loads is analyzed at different scour depths (0D, 1D, 2D and 3D, where D is the pile diameter). Structural response characteristics before and after seismic excitation are emphatically compared under two typical sea states: collinear wind–wave condition (COD-2.2) and non-collinear wind–wave condition (MIS-2.4). The results show that seismic excitation substantially amplifies structural dynamic responses. Meanwhile, strong seismic interference weakens the influence of wind–wave directionality to a certain degree, lowering the response difference between the COD-2.2 and MIS-2.4 cases. It is further found that scour depth remains the dominant factor controlling pile internal forces and foundation lateral deformation even when seismic effects are incorporated. Moreover, under the selected Chi-Chi ground motion, scour aggravation markedly increases the seismic response amplification and internal force concentration of the structure. This research provides a theoretical reference for the multi-hazard resilience design and assessment of wind turbine foundations under complex marine environments.

Bibliographic Information