大跨人行悬索桥非线性静风稳定性分析

摘要

The nonlinear aerostatic stability of a 420m-main-span suspension pedestrian bridge was analysed numerically.Based on aerostatic coefficients of the main girder measured in wind tunnel tests,nonlinear influences caused by the structure and aerostatic load were analysed by using incremental double iteration method.The results conclude as follows:the structure deformation varying with wind speed shows obvious nonlinearity,and the aerostatic instability mode is of the characteristic of space deformation of bending-twisting coupling mode;comparing with the highway bridge,the torsional stiffness of the bridge due to main cables accounts for a greater proportion of the stiffness of the long-span suspension pedestrian bridge.The critical wind velocity and the reason of aerostatic instability can be got by tracing the stress in the main cable with the variation of wind speed;nonzero initial wind attack angle can reduce the critical wind speed;central buckles and anti-wind cables can raise the critical wind speed.The aerostatic instability mode after the installation of central buckles is the bending-twisting coupling mode of main girder,and the aerostatic instability mode after adding the measure of anti-wind cables is the local structural buckling due to the wind cables and hangers stress relaxation.The results are beneficial to the further research of long span narrow bridge aerostatic stability.%基于风洞试验所测加劲梁静力三分力系数，在综合考虑静风荷载非线性、结构几何非线性基础上，采用双重迭代计算分析方法对主跨420 m大跨窄人行悬索桥进行静风稳定性全过程分析。结果表明，结构变形随风速变化呈明显非线性，静风失稳形态弯曲扭转空间耦合变形特征显著；较公路桥大跨人行悬索桥主缆提供的扭转刚度比重更大，跟踪两主缆跨中应力随风速变化情况可定义静风失稳临界风速及与分析静风失稳原因；非零初始风攻角会降低静风失稳临界风速；中央扣及抗风缆均能提高静风失稳临界风速。施加中央扣措施，失稳形态为主梁结构弯扭失稳；施加抗风缆措施，失稳形态为抗风拉索、抗风缆应力松弛导致局部结构失稳。该研究可为大跨窄桥静风稳定性能及提高静风稳定性提供科学依据及参考。