中文摘要：

为方便计算高墩固结体系矮塔斜拉桥的纵飘基频,基于三跨高墩固结体系矮塔斜拉桥,应用Rayleigh法,推导其纵飘基频公式,并提出了名义单位质量的抗弯刚度的概念,最后对此公式的可行性进行了算例验证,并讨论了该公式的应用对象.研究表明：高墩固结体系的矮塔斜拉桥第一阶振动以桥墩的纵飘为主,给出的能量法得到的纵飘基频计算值与有限元值误差能满足概念设计阶段的要求,该公式适用于高墩固结体系矮塔斜拉桥的纵飘基频估算.

英文摘要：

In order to calculate longitudinal fundamental frequency of the rigid frame extradosed cable- stayed bridge with high pier conveniently, the three-span rigid frame extradosed cable-stayed bridge with high pier was taken as research object, frequency formula for longitudinal vibration mode of extradosed cable-stayed bridge is derived by the Rayleigh method; and then the concept of nominal unity mass anti-bending rigidity is introduced. Finally, the presented theoretical formula of fundamental frequency is validated by case study; and the frequency formula for longitudinal vibration is discussed therein. The results indicate that the basic oscillation of rigid frame extradosed cable-stayed bridge with high pier consists of the longitude vibration of pier. The fundamental frequency calculated by the recommended method has an error compared with the finite element method （FEM） result, which meets with the requirement of conceptive design. The presented theoretical formula can apply to estimate frequency for longitudinal vibration of rigid frame extradosed cable-stayed bridge with high pier.