基于变形协调原理的多塔斜拉桥边塔纵向抗推刚度

Longitudinal restraint stiffness of the side tower for multi-tower cable-stayed bridge based on the principle of deformation coordination

为深入探寻多塔斜拉桥刚度特征,将斜拉索对桥塔的约束比作弹簧刚度的理念引入多塔斜拉体系。选取多塔斜拉桥的最典型形式——三塔斜拉桥建立弹簧刚度等效模型,基于变形协调原理,求解多塔斜拉桥边塔纵向抗推刚度,对推导的公式进行算例验证,并分析结构主要参数对桥塔纵向抗推刚度的影响。研究结果表明:对边塔非边跨施加均布荷载时,本文推导的塔顶偏位公式与有限元解之间的误差在7.8%以内。文中解的结果比有限元解偏大的主要原因是:文中公式解没有考虑斜拉索的垂度效应,均布荷载满布边塔非边跨时所产生的水平力实际上没有完全作用在边塔,有一部分消耗在拉索的垂度效应中。本文推导的边塔纵向抗推刚度公式可以较真实地反映多塔斜拉桥边塔的刚度特征,符合多塔斜拉桥概念设计的要求。

In order to explore the stiffness characteristic of multi-tower cable-stayed bridge, this paper introduces an idea to multi-tower cable-stayed bridge with the cable constraint the tower as spring stiffness. The three tower cable-stayed bridge was taken as research object, which is the simplest type of multi-tower cable-stayed bridge.Based on the principle of deformation coordination, longitudinal restraint stiffness of the side tower for multi-tower cable-stayed bridge was solved out, and a series of estimating formulae are provided and calculating outcomes are compared with that of a finite element model. Besides the influence of main structure parameters for longitudinal restraint stiffness of the side tower were also analyzed. The results show that on the side tower with uniformly distributed load, the errors between the side tower deformation formula in this paper and finite element are within 7.8%. The main reason of the result of the formula in this paper bigger than finite element model is the formula does not consider the sag effect of the cable. The horizontal force caused by the uniformly distributed load with side tower has not full effect at the side tower, and a part of the consumption is in the sag effect of the cable. The presented theoretical can meet the requirements of the conceptual design, and it is suitable for the stiffness requirements of multi-tower cable-stayed bridge.