多塔悬索桥变形特性

为了探究多塔悬索桥初步设计阶段参数取值,将主缆等效为具有一定刚度的弹簧,建立多塔悬索桥静力力学分析模型;基于加载跨与非加载跨主缆水平力平衡以及塔顶位移、主缆伸长与主缆垂度变化的关系,推导了塔、缆变形解析公式,通过建立的有限元模型进行验证;分析了主要设计参数对结构变形的影响.结果表明:提出的公式可用于初步设计阶段多塔悬索桥的结构变形估算;桥塔刚度及恒活载比值对结构变形影响显著,通过增大桥塔刚度或恒活载比值均可有效减小结构变形;垂跨比对结构变形的影响与桥塔刚度有关,桥塔刚度较小时宜采用较小垂跨比,桥塔刚度较大时,宜采用较大主缆垂跨比;结构变形随跨径的增大迅速减小,当跨径增大到2 000 m时,变形不再控制多跨悬索桥设计;主跨跨数超过3跨时,继续增加主跨跨数对结构变形影响较小.

Deformation Characteristics of Multi-tower Suspension Bridges

To study the parameter choice during the preliminary design stage of the multi-tower suspension bridge, static mechanics analysis model was set up for multi-tower suspension bridges by using main cable equivalent to a spring with some stiffness. Calculation methods for deformation of multi-span suspension bridges were proposed based on balance of horizontal forces between loaded span and unloaded span. Analytic expressions of main cable deformation were derived and validated, which could be applied in the preliminary design. Effects of major design parameters on the deformation of multi-tower suspension bridges were studied. Research shows that changing sag-to-span ratio has a little influence on the deformation; tower stiffness imposes a significant effect on deformation, and structural deformation decreases with a increment in tower stiffness;with the increment of span length and the ratio of dead load and live load, the structural deformation decreases;increasing the number of main span almost has no effect on deformation of the structure when there are more than three main spans.