大跨度椭圆抛物面弦支穹顶结构的缺陷敏感区域分析

Analysis of Imperfection Sensitive Region of Long-Span Elliptic Paraboloid Suspended Dome Structure

厚街体育馆钢屋盖采用大跨度椭圆抛物面弦支穹顶结构,支座间净跨110m×80m,上部单层网壳矢高9.4 m.分别以此结构与相应的单层网壳为分析对象,采用改进的随机缺陷模态法,对两类结构的缺陷敏感区域进行对比研究.在此基础上,进一步探讨局部拓扑形式改变及活载半跨分布对弦支穹顶结构缺陷敏感区域的影响.研究表明:弦支穹顶结构的缺陷敏感区域位于上部单层网壳;弦支穹顶与相应单层网壳的缺陷敏感区域有较大差异,下部索杆体系的引入明显改善了上部单层网壳的缺陷敏感性;局部拓扑形式的改变,可有效降低结构的缺陷敏感程度;活载的半跨分布对传统拓扑形式弦支穹顶结构缺陷敏感区域的影响并不大,但对于该结构上部单层网壳中心区域的影响较为显著.

A long-span elliptic paraboloid suspended dome structure, in which the clear span between supports is 110 m × 80 m and the rise of the upper single-layer reticulated shell is 9.4 m, is employed in the steel roof of Houjie Gymnasium. The imperfection sensitive regions of the structure and the corresponding single-layer reticulated shell are comparatively investigated by means of the advanced random imperfection mode method. On this basis, the in- fluences of the local topological form change and the half-span distribution of the live loads on the imperfection sen- sitive region of the suspended dome are further discussed. The results show that （ 1 ） the imperfection sensitive re- gion of the suspended dome is located in the upper single-layer reticulated shell; （2） the imperfection sensitive re- gion of the suspended dome is significantly different from that of the corresponding single-layer reticulated shell, and owing to the introduction of the lower cable-strut system, the imperfection sensitivity of the upper single-layer reticulated shell is remarkably improved; （3） by changing the local topological form, the imperfection sensitivity of the structure can be effectively reduced ; and （4） the half-span distribution of the live loads has little influence on the imperfection sensitive region of the suspended dome with a traditional topological form, but has a significant in- fluence on the central region of the upper single-layer reticulated shell of this kind of suspended dome.