Evaluation of Aerodynamic and Seismic Coupling for Wind Turbines Using Finite Element Approach

The behavior of a wind turbine consists of complex interactions between different components and subsystems. As more large scale wind turbines are constructed in seismically active regions, earthquake excitation makes an even more challenging problem when calculating extreme loads. Turbine specific simulation codes that directly include simulation of aerodynamics and seismic loading often include considerable simplifications to the turbine model that might cause unrealistic scenarios when designing such structures. Turbine related simulation codes are also often unfamiliar for civil engineers. For these reasons, it is desirable to come up with an approach that can handle a more realistic model that can simulate coupling between the influenced loads involved. In this work, the emphasis is put on the response of the tower of a large scale wind turbine subjected to aerodynamic and seismic loading. To capture the inclusive behavior of the structure, finite element analysis was used that consisted of shell elements for the tower, and beam elements for the blades. Various interactions were also used to model the rotation of the rotor during the operation of turbine under wind loading. Results of this approach were compared with previous findings using a selection of ground motions and turbulent wind fields. It is shown that for the turbine operational condition, the presented approach agrees well with the previously verified design codes. The outcome of this approach will provide a better understanding of more detailed structural aspects of wind turbines such as nonlinear behavior and failure criteria that might be considered necessary for a more comprehensive design.