弦支穹顶结构的自振特性及地震响应分析

Natural vibration characteristics and seismic response analysis of suspen-dome

弦支穹顶结构是基于张拉整体思想和单层球面网壳技术的一种新型复合空间结构体系,为了研究弦支穹顶的自振特性和地震响应,采用有限元软件,对结构的矢跨比、撑杆高度、环索布置方式和预应力大小等进行了参数分析,并对单层网壳和两种不同布索形式的弦支穹顶结构进行了El Centro波地震响应对比分析。结果表明:矢跨比和撑杆高度对结构自振特性影响较大,而拉索预应力大小对结构影响较小。支座的弹簧刚度对弦支穹顶的高阶频率的影响不及对基频的影响,当弹簧刚度较小时,其对结构基频的影响基本上是线性的;刚度较大时,对基频的影响很小。在固定铰支承条件下,与单层网壳结构相比,弦支穹顶不能减小地震产生的结构位移的振幅。弦支穹顶结构整体内力值偏大,在布索层数相近的情况下,不同的弦支穹顶的撑杆和拉索的内力变化趋势和数值相近。

Suspen-dome is a novel hybrid structural system, which is based on the tensegrity system and single-layer reticulated dome. The natural vibration characteristics and seismic responses of suspen-dome are discussed in this paper. With the finite element analysis software, parameter analyses of the rise-span ratio, heights of strut, arrangement mode of hoop cables and prestressed degrees of cables for suspend-dome structures have been carried out. And the seismic responses of single-layer lattice shells and two kinds of suspen-domes are analyzed by inputting El Centro wave. The rise-span ratio and height of strut have greater influence on the natural vibration characteristics of structure than the prestressed degrees. The stiffness of spring support has greater influence on the fundamental frequency of suspen-dome than on the higher order frequency. When the stiffness of spring support is relatively small, the relationship between the stiffness and the fundamental frequency is approximately linear; when the stiffness is relatively large, there is decreasing influence on the fundamental frequency. With the hinge support, the seismic displacement response of suspend-dome structure is not less than that of single-layer lattice shells. Moreover, the internal forces of suspen-dome are larger than that of single-layer lattice shells. When the layer numbers of different cable arrangements are close, the trend and magnitude of the internal force of the struts and cables of the different suspenddome structures are similar.