Abstract: In order to analyse the relation between structural strength loading demands of wind turbines and design earthquake intensity,a universal seismic analysis framework has been developed based the open source tool FAST with taking into account the soil structural interaction effect using Wolf method.Three distinct wind turbines (AOC 50 kW,WindPACT 1.5 MW and NREL 5 MW) have been selected as the research objects.The structural dynamic responses of the wind turbines operating in different modes under multiple loadings combined by 101 earthquake excitations and turbulent wind are obtained.The results indicate that earthquake excitation increases the vibration amplitude of tower-top significantly.The fluctuation range of nacelle acceleration of NREL 5MW has been widened around 4.7 times under the influence of an earthquake event with a peak of ground acceleration of 2.14 m/s².Emergency shutdown is induced.The aerodynamic damping of the rotor decreases rapidly due to pitching to feather resulting in more severe vibration with a larger amplitude.It indicates that the emergency shutdown cannot mitigate the vibration on tower-top of the wind turbine subjected to an earthquake event.The maximum tower-base moment demand increase linearly with the peak of target earthquake acceleration.A novel model of pseudo-spectral acceleration and tower-base moment demand is developed for better estimations of seismic loading demands.The proposed model can estimate the tower-base moment demands more efficiently for the different wind turbines subjected to different earthquakes compared to present models.The findings can be referred for structural design of aseismatic wind turbines.

Key words: estimation model, seismic events, structural strength, wind turbine