Vibration control of jacket offshore wind turbine subjected to earthquake excitations by using friction damper

Recently, a large amount of massive and large wind turbines have been constructed, and many of them are located in areas prone to seismic activity. These structures are generally vulnerable to lateral loads, such as wind loads, wave loads, and especially seismic loads. With the purpose of reducing the seismic damage, a damper system is utilized to control the vibration of NREL 5-MW offshore wind turbine (OWT) with jacket support structure combined with a diagonal bracing friction damper system. Seismic performances of the wind tower structure are studied for two cases: the structures without and with friction dampers. The structural responses to three earthquake records including Cape Mendocino, Duzce and Imperial Valley earthquakes are evaluated by nonlinear dynamic analyses using OpenSees program. Numerical results showed that the proposed vibration control method is effective in reducing the seismic responses of the wind turbines.