葵花双撑杆型索穹顶预应力及多参数敏感度分析

Analysis of Multi-parameter Sensitivity and Prestressing Force Distribution of Sunfolwer-type Cable Dome with Double Struts

摘要:

提出了一种新颖的葵花双撑杆型索穹顶结构，具有斜索数量少、施工张拉成形方便、可有效防止环索滑移等显著特点；基于节点平衡方程，给出了全套预应力态索杆内力的递推计算公式，对结构的下弦环索数、矢跨比、下弦节点位置、是否开设内孔等参数做了72个算例，并验证了预应力态索杆内力计算公式是精确解.分析结果表明，结构预应力态时索杆内力从内圈向外围是成倍递增的；下弦节点位置沿竖向与水平向发生改变后，均使预应力态索杆内力发生较大的变化；矢跨比在0.1~0.2范围内时，矢跨比对索杆内力的影响较小；说明了结构矢跨比、结构中部是否开孔属非敏感性参数，而下弦环索数、下弦节点位置则属敏感性参数，在进行结构设计时应重点考虑.该结构形式的提出为索穹顶的选型、设计计算和施工提供了新方案、新思路.

关键词:葵花双撑杆型索穹顶; 结构构形; 预应力态; 简捷分析法; 敏感度分析; 算例计算

Abstract:

A new type of sunflower-type cable dome with double struts, which has the characteristics of fewer number of inclined cables, convenient tensioning forming and effective prevention of ring slip, is proposed in this paper, Based on the nodal equilibrium equation, a recursive calculation formula for the internal force of the prestressed cable strut is given. 72 examples are given, including the number of lower chord cables, the ratio of sagittal span and the position of lower chord joint of the structures. It is verified that the formula for calculating the internal force of prestressed cables is exact solution. The analysis results show that the internal force of the cable strut increases exponentially from the inner ring to the periphery. When the position of the lower chord joint changes vertically or horizontally, the internal force of the prestressed cable strut is changed greatly. When the rise-span ratio is within the range of 0.1~0.2, the influence of it is less. It is shown that rise-span ratio and the opening in the middle of the structure are non-sensitive parameters, while the number of the lower chord cable and the position of the lower chord joint are sensitive parameters, and should be considered in the design of the structure. The proposed structure provides new forms and new concept for the selection, design and construction of cable dome.

Key words:sunflower-type cable dome with double struts; structural configuration; prestressing state; simple analysis method; sensitivity analysis; calculated examples