中文摘要：

在Rayleigh能量法和Southwell＇s频率合成法的基础上,将悬索桥裸塔的振动基频表示成由各变形元和惯性元组成的子系统频率的合成,通过挠度函数的合理选取,导出了悬索桥裸塔振动基频的近似算法。以泰州大桥钢中塔为计算实例,分析了顶部附加质量比、结构自身剪切变形、承台振动对基频的影响。数值计算与实桥现场环境振动试验表明,桥塔振动基频会随顶部附加质量比增大而减小,忽略剪切变形对计算结果影响甚微,但承台的振动不可忽略。该方法不仅适用于底部固定以及顶端带有附加质量的塔式结构,也适用于其他截面复杂的高层建筑、烟囱等高耸工程结构。

英文摘要：

Based on the combination of Rayleigh energy method and Southwell frequency composition method,fundamental vibration frequency of free-standing pylon of suspension bridge was denoted as a composition of frequencies of several subsystems which consists of deformation components and inertia components,thus the approximate algorithm for calculating fundamental vibration frequency of suspension bridge＇s free-standing pylon was derived through rational selection of deflection function.Taken the middle steel pylon of Taizhou bridge as a calculation example,the impacts of the top additional mass ratio,structure shear deformation and vibration of bearing platform on fundamental vibration frequency were analysed.The numerical calculation and real bridge field vibration test show that（1） fundamental vibration frequency of pylon would decrease with increasing of the top additional mass ratio;（2） although ignoring shear deformation has little impact on the calculation result,the vibration of bearing platform could not be ignored.The algorithm is not only suitable for the pylon with fixed bottom or having additional mass on its top,but also suitable for other high buildings,chimneys and so on with complicated section.