下弦管内预应力梭形空间桁架静力分析

STATIC ANALYSIS OF PRESTRESSED BOTTOM CHORD SHUTTLE SPATIAL TRUSS

下弦管内预应力梭形空间桁架结构是梭形空间桁架与预应力相结合所产生的一种新型空间结构形式。探讨其结构分析的两种计算方法——等效荷载法和有限元法,分析预应力作用下桁架各杆件的受力性能,并讨论预应力对桁架刚度的影响。计算发现,预应力对上弦的影响很小,在跨中引起的压力接近于零;预应力对下弦的影响较大,在跨中引起的压力与预应力值相当。预应力对梭形桁架的刚度贡献主要包括索张拉预应力桁架反拱的主动控制作用和索作为下弦构件的被动控制作用,索张拉使结构内部产生的预应力刚化效应较小。

A prestressed bottom chord shuttle spatial truss is a new kind of prestressed structure. In this paper, simplified calculation method and finite element method are also discussed, mechanical behavior of the truss members under the action of prestress is studied, and influence of the prestress on stiffness of the truss is analyzed. The calculation shows that the prestress has a small effect on upper chord,and a greater one on bottom chord; the pressure in midspan produced by the prestress is equivalent to the value of the prestress.