大跨度斜拉桥的静风失稳特性

Aerostatic Instability Characteristic of Long-span Cable-stayed Bridges

大跨度桥梁发生静风失稳的临界风速可能低于动力失稳的临界风速。结合斜拉桥的结构特点,探讨了已有的非线性失稳分析方法,提出了一种静风失稳的复合标准判断方法,基于MSC.MARC和Python脚本语言,综合考虑结构几何非线性和静风荷载非线性影响,探讨了大跨度斜拉桥空气静力失稳特性。结果表明:升力系数和力矩系数在大跨桥梁静力失稳全过程分析中起到关键作用;风速达到或接近失稳临界风速时,大跨度斜拉桥梁的结构非线性问题十分突出,静力失稳表现为十分明显的弯扭耦合形态。

The critical wind speed of the aerostatic instability of long-span bridges may be less than that of the aerodynamic instability,Based on the discussion of the existing nonlinear aerostatic instability analysis,a composite criterion for judgment of aerostatic instability was presented according to structure characteristics the of cable-stayed bridges.With consideration of effects of geometric nonlinearity and the aerostatic load nonlinearity,the aerostatic instability of a long-span cable-stayed bridge was analyzed based on MSC.MARC and Python scripts.This result shows that（1） wind lift coefficient and moment coefficient play the key role in the whole process analysis of aerodynamic instability of the bridge;（2） as nonlinearity is usually significant for long-span cable-stayed bridges under the critical wind speed,the general characteristic of static instability is bend-torsion form.