悬索桥主缆初始位形的悬链线方程精细迭代分析法

ACCURATE ITERATION METHOD TO CALCULATE THE INITIAL STATES OF MAIN CABLES OF SUSPENSION BRIDGES

悬索桥非线性有限元法采用悬链线单元精度高,推导了基于自重约束方程,求解两种设计条件下主缆初始位形的悬链线精细迭代法公式,该方法能够计算主缆变形后自重荷载集度的变化。根据索鞍的受力特点,推导了不平衡索力与索鞍预偏量之间增量函数形式的显式刚度方程,导出了索鞍弧顶主缆曲线的无应力索长的精确计算公式。算例结果表明,方法精度高,计算稳定且收敛快。

The catenary element has higher precision than other elements in nonlinear analysis of cable-stayed bridges. Based on the self-weight constraint equation, a method of accurate catenary iteration is developed to find the initial states of main cables of cable-stayed bridges with two design parameters known in advance. The proposed method can calculate the self-weight density variations of cables. Based on the mechanical characteristic of cable saddle, explicit tangent stiffness equations relating cable tension and saddle offset are deduced, and the accurate formulas of non-stressed cable length on saddles are also obtained. The example results show that the proposed method is accurate, stable and quickly convergent.