Abstract:Comparative evaluations of failure probability were conducted with respect to an in-service wind turbine under earthquakes and wind loads. Firstly, to obtain the hazard curves under earthquakes and wind loads for a specific region where the wind turbine was built, hazard probability analyses were performed based on the special lifetime of this wind turbine. Then, to obtain structural fragility curves under earthquakes and wind loads, a blade-tower finite element model was established by shell and beam elements in a commercial finite element software and multiple sets of time histories were selected or generated based on the target seismic response and wind spectra. Numerous incremental dynamic analyses under material and geometric nonlinearity were conducted, respectively. Finally, according to the results of hazard and fragility analyses and the law of total probability, failure probabilities of the wind turbine under the two different disasters were compared. Results showed that the issue of conservative calculations was avoided by the hazard analysis based on the specific lifetime of wind turbines. On the account of the controllable pitch installed on the wind turbine, wind-resist responses under operational conditions were similar. Additionally, the failure probability of the wind turbine under wind loads was larger compared with the probability under earthquakes. On the one hand, the wind turbine was a long-period structure whose frequency was located at a point in the descending range of the seismic response spectrum; therefore, earthquake response was relatively low due to the short-period dynamic loads. On the other hand, the wind-rich areas were typically selected as the sites for wind farms, enlarging the probability of strong wind conditions and improving the failure probability under wind loads. The conducted investigations in this paper, considering the special lifetime of the wind turbine, guides the development of the multi-hazard probability evaluation in the wind turbine field.