内凹形轮辐式张拉结构基本体系找形与关键参数分析

Form finding and key parameter analysis for concave wheel-spoke shaped pretension structure system

为了解内凹形轮辐式张拉结构的受力性能,建立内凹形结构体系的初始预应力与构型的近似关系,实现结构的初始预应力快速估算,采用参数化设计软件并编制的找形分析插件,找到合理的结构形态和预应力分布。同时对结构基本体系的关键参数进行分析,得出关键参数的合理取值范围。分析结果表明,索桁架的上、下径向索在控制矢跨比的条件下可以采用悬链线、抛物线和圆弧线;根据建筑造型和受力性能分析,在实际工程中建议索桁架的上、下径向索采用抛物线;结构上径向索的矢跨比合理取值范围为1/40～1/20,下径向索的矢跨比合理取值范围为1/40～1/30;内凹形轮辐式张拉结构径向索桁架合理取值为32～44榀;结构外压环与上、下内拉环的高差比值c1/c2合理取值范围为1.0～1.5,在该取值范围内,上、下径向索的预应力值相差在30%以内,结构内力分布比较均匀,刚度较好。

In order to understand the mechanical properties of concave wheel-spoke shaped pretension structure, calculation formula of concave structural system＇ s initial prestress was developed and could figure out structure＇ s initial prestress rapidly. Using the formula with the parametric design software and plugins of form finding analysis,the rational structure shape and prestress distribution can be obtained quickly. By studying the key parameters of concave wheel-spoke shaped pretension structure, the reasonable ranges for the key parameters, which could provide a reference for engineering practice were also found. Analysis shows the upper and lower radial cables can be adopted catenary, parabolic or arc under control rise to span ratio. Based on architectural shape and force performance analysis, using the parabolic upper and lower radial cables of cable truss in the actual project is proposed. The reasonable rise to span ratio of the upper radial cables ranges from 1/40 to 1/20, and the reasonable rise to span ratio of the lower radial cables ranges from 1/40 to 1/30. The reasonable number of radial cable truss is from 32 to 44 . The upper and lower reasonable height ratio c1/c2 of outer ring to the inner pressure pu]lring ranges fi＇om 1.0 to 1.5, where the prestressing forces of the upper and lower radial cables differ less than 30% , the internal force is more evenly distributed and the structural stiffness is good.