构架式预应力抗疲劳钢管风电塔抗疲劳设计方法

An Anti-fatigue Design Method for a Novel Latticed Prestressed Anti-fatigue Wind Turbine Tower Structure

风电机组大型化逐渐成为我国中东部、南部等低风速区风电塔的发展趋势。单机容量大型化带来的机头极限荷载和疲劳荷载的提升,给传统风电单管式钢塔筒支撑结构的设计、制造和运输带来了巨大挑战。为解决此问题,提出了一种构架式预应力抗疲劳钢管风电塔,在降低支撑结构用钢量、提升结构刚度避免共振的同时,通过在塔柱钢管内张拉预应力钢绞线的方式,降低塔柱焊接节点所受疲劳外荷载应力幅的平均应力,从而延长其疲劳寿命,并改善疲劳脆性破坏特性。基于上述预应力抗疲劳构架塔概念,通过整理总结相关规范和标准的规定以及文献研究结论,论证了降低平均应力对延长具有低值残余应力的焊接节点疲劳寿命的可行性,并提出了一种预应力抗疲劳设计方法。最后,以某地拟建的160 m构架式预应力抗疲劳钢管风电塔为例,展示了其预应力抗疲劳设计的全过程。结果表明,相比于单纯增大构件截面积来抵抗疲劳,预应力抗疲劳设计具有更好的经济性和安全性。

Large-scale wind turbines have gradually become an option for wind turbine towers in low wind speed areas such as central and eastern and southern China.The increasing single machine capacity leads to larger ultimate and fatigue loads, which brings great challenges to the design, manufacturing and transportation of traditional single-tube steel tower.To solve these problems, this paper proposes a structure, namely, latticed prestressed anti-fatigue wind turbine tower, which does not only reduce the amount of steel for support structure, but also avoids the resonances owing to the increasing stiffness of support structure.In addition, steel strands, which are arranged inside the tower columns, are tensioned to put pressure on the welded joints of support structure to decrease the magnitude of mean stress of fatigue stress cycles, leading to longer fatigue life and better fatigue failure characteristics.This paper demonstrates the feasibility of prolonging fatigue life by applying compressive stress based on various fatigue standards and literature research results, and proposes a prestressed anti-fatigue design method.At last, this paper takes a 160 m latticed prestressed anti-fatigue wind turbine tower to be built as an example to illustrate the complete process of anti-fatigue design by prestress.The calculation results show that when compared with simply increasing the cross-sectional area of the components to resist fatigue loads, the prestressed anti-fatigue design method is safer and more economical.