A Simplified Approach for Implicitly Considering Aerodynamics in the Seismic Response of Utility Scale Wind Turbines

For large turbines in regions of high seismic hazard, earthquake excitation is important to consider when developing extreme loads. Turbine specific codes that directly simulate aerodynamics and seismic loading are often unfamiliar for civil engineers involved in site specific permitting. For this reason, a simplified procedure that produces equivalent results for the combination of independently calculated aerodynamic and seismic loads is desirable. In this work, results from direct simulations of coupled aerodynamic and earthquake loads are compared with those from superposition of individual analyses to assess and advise on the suitability of such an approach. Results from different loading cases show that direct simulation can be approximated through a combination of loads from independent simulations by using an appropriate level of viscous damping for seismic response. It is shown that, for the considered turbine, the presence of aerodynamics requires the use of higher equivalent viscous damping to approximate the seismic demand while under operation through conventional earthquake analysis procedures.