800m超大跨巨型斜拉下穿索承网格结构拉索布置及参数分析研究

Cable arrangement and parameter analysis for cable-stayed and underneath-cable supported megagrid structure

对适用于800m超大跨度的巨型斜拉下穿索承网格结构的预应力系统进行了优化研究,提出并对比设置不同数量斜拉索的布置方案,得到较为合理的拉索布置方式.分析了下穿拉索方式对结构性能的影响,下穿拉索通过撑杆为中部结构提供弹性支承,使中部网格结构受力均匀.提出索承内拉环的改善方案,显著降低内拉环索力.采用逆迭代法对结构进行找形分析,获得合理的拉索初始预应力分布,有效控制结构初始态的位移.对不同的拉索初始预应力度进行对比分析,研究表明初始预应力降低会使结构刚度显著降低,但并不能降低拉索用量.最后对比分析了钢拉索和碳纤维增强复合材料拉索对结构性能的影响.

This research focuses on prestress cable system for a new cable-stayed and underneath-cable supported megagrid structure with a super-large span of 800 m.Different types of cable arrangement are compared,and reasonable cable arrangement is obtained by comparing the cable internal force.The inverse iteration method is applied to the form-finding process of the cables.Reasonable distribution of initial prestress on the cable leads to a reduction in the displacement of the structure in the initial state.Research on prestressed cables shows that the amount of cables will not dramatically decrease with the decline of prestressing force,but the structural stiffness will be weakened obviously. The contribution of underneath-cable has been proved that it can support the middle part of grid structure through stay strut,and balance the internal force.The cable-loop can reduce the cable force as well.At last,the structural properties of steel cables and CFRP cables are compared.