Dynamic Analysis of a Reinforced-Concrete Post Tensioned Wind Turbine Tower

Abstract

Wind energy turbines have drawn great interest especially for the last 2 decades. Today newly developed high-power wind energy generators require long blades and tall towers with large base diameter which exceeds the allowable width for highway transportation. The tower must also be divided through longitudinal and connected on site to overcome transportation problem. In this case welding difficulties, other technological aspects on site increase the cost of steel towers. However, concrete towers precast or cast on site, becomes a competitive alternative to current steel solutions for the wind energy towers, due to its lower cost and higher durability. As the generator on top produces a variable and continues vibration the dynamic properties of the towers becomes more important than any other structures due to resonance effect. In wind turbines, inexact calculation of natural frequencies or change of natural frequencies due to concrete cracking by time may harm the whole structure. So this makes post tensioning very important for wind energy towers. Post tensioning avoids tension strength which in turn prevents fatigue cracks in concrete elements which are exposed to tension strength. In this paper, the concept of a 100 m tall modular prefabricated posttensioned high-performance concrete 3.6 MW wind generator tower is presented. In the study the finite element model of the tower is prepared and under wind and rotor loads the structural analysis of the tower is presented.