In order to calculate the vibration frequencies of suspension bridges with asymmetric arrangement more rapidly,a three-span continuous girder suspension bridge with double-tower and asymmetric side-span was taken as research object.The frequency formulas for the 1st vertical and torsional vibration modes were derived based on the Rayleigh-Ritz's method considering the influence of asymmetric side-span on vibration frequencies,and the generality of the formulas was discussed.The estimation formula for the fundamental frequency of the single-span suspension bridge was obtained by resolving the limit of some related parameters of the three-span suspension bridge with asymmetric side-span.Finally,the accuracy of the proposed formulas was examined by the finite element method (FEM).The results show that the errors between the frequencies of 1 st anti-symmetric vertical and torsional vibration modes calculated by the proposed method and the FEM are 9.2％ and 6.7％,while the errors between the frequencies of 1st symmetric vertical and torsional vibration modes calculated by the proposed method and the FEM are 5.0％ and 4.4％,which can meet the requirement of design phase.Finally,the influence of the correlation coefficient on the fundamental frequency was discussed.The results indicate that the proposed formulas can be applied to guide the scheme selection and preliminary design of the simplesupported single-span or the three-span continuous girder suspension bridges with asymmetric side-span.%为了快速计算不对称布置的悬索桥振动基频,基于双塔边跨非对称的三跨连续加劲梁悬索桥,在考虑不对称边跨对振动基频的影响下,采用Rayleigh-Ritz法分别推导了一阶正对称、反对称竖弯及扭转振动基频估算公式,并讨论了公式的通用性.将边跨不对称的三跨连续加劲梁悬索桥跨径相关的参数取极限即可得到简支单跨悬索桥的基频估算公式,最后通过有限元法验证估算公式的精度.研究结果表明:基于边跨非对称悬索桥一阶正对称、反对称竖弯频率的有限元解和文中解误差分别是9.2％和6.7％,而一阶正对称、反对称扭转频率的有限元解和文中解误差分别是5.0％和4.4％,表明推导的估算公式解与有限元解误差能满足设计阶段的要求.最后讨论了跨径相关系数变化对基频的影响,该公式可以方便指导边跨非对称的三跨或简支单跨悬索桥方案选择和初步设计.
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