Radiative Damping of Offshore Wind Turbine Gravity Base Foundations at Low Frequencies
With the fast increasing need of clean energy, more and more offshore wind turbines (OWTs) are being planned or constructed. Some offshore wind turbines are supported on Gravity Base Foundations (GBFs). As tall and slender offshore wind turbines are very sensitivity to the dynamic loadings at low frequencies, if designed improperly, it is likely to cause resonances. On the other hand, most of the designs ignore the radiative damping of GBFs, which will lead to a conservative solution and a cost of more money. In this paper, by referring to three different models, the corresponding vertical, horizontal and rocking damping ratios for a typical GBF at low frequencies are obtained and compared, respectively. With these damping ratios obtained, one can develop a more realistic and economic model to calculate the dynamic responses of offshore wind turbines on GBFs under both vertical and horizontal forces at low frequencies.