Seismic Response of a Prestressed Concrete Wind Turbine Tower

Abstract

This paper compares the seismic load of a 5-MW wind turbine supported by a 100-m-high prestressed concrete tower calculated via time history analysis and response spectrum analysis using elastic acceleration spectrum provided by the China Aseismic Code for Buildings. With 5 % damping ratio, the fixed-base multi-degree of freedom model and finite element model considering soil structure interaction are used for response spectrum analysis and time history analysis, respectively. The results indicated that the seismic load calculated by response spectrum analysis is significantly larger than those obtained using the time history analysis method. It implies that the seismic load determined from common building code procedures along with other loads for wind turbine foundation design is too conservative. Within this paper, the effects of damping ratio, horizontal acceleration amplitude, spring stiffness, and damping coefficient of foundation on the seismic load of the prestressed concrete wind turbine tower are discussed. It is shown that the seismic load with mode damping ratio for the prestressed concrete wind turbine tower is not significant when compared with traditional tubular steel tower designs. The maximum moment demand at the base of the tower may be controlled by earthquake loading as the seismic fortification intensity lever is more than seven. The foundation spring stiffness has an immense impact on the base bending moment and the natural frequency. Finally, seismic load should be considered more in detail when designing wind turbines that are supported by concrete towers, particularly for turbines over 100 m height and located in seismically active zones.