Analysis on Dynamic Seismic Response of a Wind Turbine Tower in Time-Frequency Domain Considering SSI Effects

To analyze the dynamic response of a wind turbine tower under combined wind-earthquake actions, a soil-structure interaction model was established based on Wolf method, following which a seismic load module was developed by using open source software Fast, so as to study the vibration characteristics and response amplitude of the tower in different soils. Results show that the seismic load greatly intensifies the vibration of the tower, with obviously increased amplitude of vibration at the first-and second-order natural frequency. At the fortification intensity of 8, the vibration of tower top is mainly excited by seismic load, slightly influenced by aerodynamic load. Due to different characteristics of damping and seismic response spectrum, the response amplitude and vibration characteristics are quite different for the tower in different soils. Under rated wind conditions, the lateral displacement of tower top has an increase of 316%, 242%, and 265% respectively for the tower in still clay soil, rock still soil and soft soil, compared with the condition without earthquake.