葵花型索穹顶初始预应力分布的简捷计算法

葵花型索穹顶是美国工程师LEVY和JING在GEIGER设计的肋环型索穹顶基础上开发的一种新型穹顶,并应用于1996年亚特兰大奥运会主赛馆的屋盖结构———乔治亚穹顶。由于索穹顶结构的刚度由预应力提供,根据结构初始几何形状、构件的关联关系(拓扑)确定形成一定刚度的初始预应力是索穹顶设计首先要解决的问题。本文针对葵花型索穹顶结构提出了确定初始预应力分布的简捷计算法。该法从节点平衡关系入手,推导了不设和设有内环的葵花型索穹顶预应力杆内力一般性的计算公式。对特定参数的索穹顶结构还给出了内力计算用表。计算结果表明,随矢跨比增加,葵花型索穹顶的脊索、斜索和环索内力减小,竖杆内力增加;对应相同矢跨比,设有内环的葵花型索穹顶结构各类相应杆件内力比不设内环的内力小得多。

A simplified calculation method for initial prestress distribution of sunflower-patterned cable domes

The sunflower patterned cable dome was developed by LEVY and JING on the base of GEIGER dome and was first applied to the Georgia Dome for Atlanta Olympic Games in 1996. Since the initial prestress provides the structural stiffness, it should be determined before structural analysis. A simplified calculation method for initial prestress distribution of sunflower patterned domes based on initial geometry configuration of structure and the cognate relationship (topology)of members was proposed in this paper. It started with the equilibrium of nodal forces, then deduced the general equations for computing the internal forces of prestressing members of domes with and without inner hoops. The tables of initial prestress distribution of domes with certain parameters are also given out. The calculated results showed that the internal forces of ridge cables, diagonal cables and inner hoops of the sunflower patterned cable dome decrease, and the internal forces of vertical rods increase, as the rise to span ratio of the cable dome increases. The internal forces of different members in the cable dome with inner hoops are much more smaller than those of the cable dome without inner hoops.