非对称悬索桥对称竖弯基频的实用计算公式

Practical formulas for calculating fundamental frequency of symmetric vertical vibration of asymmetry suspension bridges

为了方便计算非对称悬索桥的对称竖弯自振基频,采用Rayleigh法分别推导了不考虑和考虑边缆和主塔刚度影响下的非对称悬索桥一阶对称竖弯自振基频的近似计算公式,提出了修正规范公式的非对称结构参数影响因子和计入边缆和主塔刚度的非对称结构参数影响因子,并给出了边缆和主塔刚度对竖向自振基频的影响系数的表达式,最后通过有限元法验证近似公式的精度.研究结果表明:在计算非对称悬索桥竖向自振基频时不能忽略边缆和主塔刚度的影响,计入边缆和主塔刚度影响的实用公式计算结果与有限元法计算结果非常接近,误差为3.3%,能满足工程上对精度的要求,可以方便指导非对称悬索桥的方案选择和初步设计.

In order to calculate symmetric vertical vibration frequencies of asymmetry suspension bridge conveniently,frequency formulas for 1st symmetric vertical vibration of asymmetry suspension bridge were derived under both cases,i.e.considering and without considering the influence of side-cable and tower stiffness on vibration frequencies based on Rayleigh＇s method.Asymmetric structure influencing factors in revised standard formulas and that considering the influence of side-cable and tower stiffness are both put forward.Formula for influencing factors of side-cable and tower stiffness on vibration frequency is also given.Finally,the result under finite element method is taken to examine the accuracy of proposed formulas.The results indicate that when calculating vertical vibration frequencies of asymmetry suspension bridge,the influence of side-cable and tower stiffness should not be ignored：and the result of calculated by proposed formulas considering side-cable and tower stiffness is much agreed with that calculated by the finite element method.The error is 3.3%,which meets the requirements of accuracy for projects.Therefore,the proposed formulas can be applied to the schematic design and preliminary design of asymmetry suspension bridge.