地锚式斜拉-悬索协作体系桥竖弯振动基频计算公式

Base Frequency Formulas of Vertical Vibration for Earth-anchored Hybrid Cable-suspension Bridge

为方便计算地锚式斜拉-悬索协作体系桥的竖向自振频率,以三跨连续支承协作体系为研究对象,在计入主塔刚度的影响下,应用能量法推导了该体系的竖向弯曲振动频率公式,并提出了主塔抗弯刚度影响系数的计算式;最后对本文所推导的公式的有效性进行了验证。研究表明:该协作体系的竖向弯曲振动基频略高于同等跨径布置的地锚式悬索桥的竖弯弯曲频率,其原因在于斜拉索对该体系刚度的贡献;本文所推导的竖弯基频计算值与数值计算误差能满足概念设计阶段的要求;该公式可用于该体系的初步概念设计中选择合理的结构计算参数。

To calculate vertical frequency of the earth-anchored hybrid cable-suspension bridge(EAHCAB)conveniently,the earth-anchored hybrid cable-suspension bridge with double-tower was taken as research object.Frequency formulas for 1st vertical vibration modes were induced by the energy method and the influence of coefficient for tower flexural rigidity was introduced.Finally,the above analytic formulas were validated by the engineering project.The results indicate that the vertical vibration character of EAHCAB is slightly higher earth-anchored suspension bridge as the same of identical span arrangement,which is caused by the contribution of cable.The error between values calculated by the analytic formulas and the finite element method(FEM)meets with the requirement of conceptual design.The analytic formulas can be applied to select reasonable parameters for the EAHCAB in conceptual design stage.