Seismic Dynamic Response Analysis of Offshore Wind Turbines Based on Monitoring Data and Quasi-static Calculation
Offshore wind turbines operate in harsh environments,with a significant number of projects in China situated near the Southeast coastal seismic zone and the Circum-Pacific seismic belt,where seismic activity is frequent,posing serious threats to offshore wind turbines safety.The geological con-ditions in China's nearshore areas are complex,characterized by both thick soft soil seabed,and exten-sive shallow geological regions with unfavorable seismic resistance conditions.The seismic response of offshore wind turbines(OWTs)is a hot topic in both engineering and academic research.In this pa-per,leveraging data from a domestic wind farm project,seismic response of OWTs were analyzed uti-lizing monitoring data from single-pile foundation turbines under seismic excitation and quasi-static analysis.Firstly,the Data-driven Stochastic Subspace Identification(Data-SSI)method was used to identify the frequency,damping,and mode shapes of the OWTs.Subsequently,the acceleration re-sponse and spectral characteristics at different measurement points were analyzed,and the time-fre-quency variations of the response at each measurement point were analyzed using wavelet transform method.Finally,employing the quasi-static calculation method,the responses of the tower and single-pile foundation under the action of inertial forces of the upper structure were analyzed and calculated.The results showed that the peak acceleration occurred at the middle of the turbine tower,and under seismic action,higher-order modes of the turbine system may be more significant.The time-frequency spectrum results showed that the turbine vibration was not predominantly governed by the first-order mode under seismic action,and the frequency variation at the top of the turbine was very complicated.The horizontal deformation of the turbine and stress in the tower met the regulatory requirements.The analysis results provide a reference for evaluating the safety of OWTs,and have engineering applica-tion significance.