高矢跨比椭圆抛物面弦支穹顶风振系数研究

Wind-induced vibration coefficient for elliptic paraboloid suspension-dome of large rise-span ratio

常州市体育馆弦支穹顶,采用Levy型索杆体系以及外部联方型和内部凯威特型网格单层网壳。与常规已研究的弦支穹顶相比,其高矢跨比使网壳具有较大刚度,其椭圆抛物面外形使屋盖在水平风载作用下既存在风吸区也存在风压区。结合工程进行了高矢跨比椭圆抛物面弦支穹顶的风振时域分析,研究了网壳和索杆系的风振响应,在风振作用下,拉索索力和支座竖向反力减小,但拉索未松弛,风载未超过恒载;索杆系应力的均值和波动范围较小;网壳的纵轴和横轴上的响应变化规律较为一致,最大竖向位移出现在靠近中心的2~4环;网壳内环的竖向位移风振系数比较均匀,外环波动较大。通过统计风振响应参数,探讨了整体风振系数的计算方法。基于响应均值和最大值的线性关系,采用风振响应与平均风静力响应的最大值之比作为适用于风载静力分析的整体风振系数,并提出不同风向下的建议值。方法简便,无需判定奇点和统计各样本响应时程。风振响应分析结论及整体风振系数计算方法和结果,可为类似结构的抗风设计提供参考。

The suspen-dome of Changzhou Municipal Gymnasium has greater rise-span ratio and elliptic paraboloid surface and is different from existing studies. The shell is stiffer and wind load shape coefficient is complex. Through wind-induced vibration analysis in time domain, structural characters were mastered and global wind-induced vibration coefficient （β） was investigated. Under the wind-induced vibration, the cable tension and vertical support reaction are both reduced, but the cables are not slack and the wind load does not surpass the dead load. The average value and fluctuation rage of the cable-strut stress are small. The response change rules on ordinate axis and abscissa axis of the lattice shell are consistent, with the maximum vertical displacement appearing at 2 to 4 rings approaching the center. The wind-induced vibration coefficients of vertical displacement at the inner rings are uniform, but those at the outer rings change greatly. Based on approximately linear relationship between mean and maximum response,β for static wind-load analysis was suggested to be the ratio of maximum response of wind-induced vibration analysis to that of static mean-wind analysis and β in different wind directions were calculated.