Experimental study on dynamic characteristics of a jacket-type offshore wind turbine under coupling action of wind and wave

Wind and wave loads are crucial factors affecting the structural safety of offshore wind turbines. With the trend towards larger wind turbines, the DTU 10 MW wind turbines have become mainstream models. The jacket-type foundation has been widely used due to its high rigidity and suitability for a wide range of water depths. Therefore, a scaled experiment was conducted on a DTU 10 MW jacket-type offshore wind turbine to reveal the dynamic characteristics of the structure. The experimental results showed that the wind loads dominated the mean of the structural response. Under the coupling action of wind and wave, the wind load suppresses the response at the structure's first-order frequency and the wave frequency. Both the wind and wave loads influence the amplitude of the structural response. The response amplitudes of the tower top displacement and foundation bending moment were smaller than the square root of the sum of the squares (SRSS) obtained from the separate wind and wave actions. Under extreme wind speed, the tower top displacement's amplitude is 75 % of the SRSS value, and the amplitude of the foundation bending moment is only 67 % of the SRSS value.