Buckling analysis of a 10 MW offshore wind turbine subjected to wind-wave-earthquake loadings

This paper investigates dynamic responses and buckling of a 10 MW monopile offshore wind turbine (OWT) subjected to multiple environmental loadings including earthquake, wind, wave and current. The finite element model (FEM) of the support structure is developed in ANSYS to obtain relatively accurate and reliable structural responses. The soil structure interaction (SSI) effects are represented using a set of lateral nonlinear springs and a vertical nonlinear spring. The SSI effects on the eigenmodes of the support structure are examined. The time series of wind and wave loads are, respectively, calculated using FAST and AQWA and then fed into ANSYS as external loads to perform the seismic analysis. The structural responses and local damage characteristics of the 10 MW OWT have been studied. The results indicate that the wind, wave and current loads in the fore-aft direction have a significant effect on the seismic responses of the OWT. It is therefore the turbulent wind, wave and current loadings cannot be ignored when performing a seismic analysis of OWTs. As a result of buckling, the change of environmental load will lead to a transition between buckling modes. These findings provide useful insights for the design of monopile offshore wind turbines.