列车激励下基于动力特性分析的辽代古塔振动规律研究

以北京辽代良乡塔为研究对象,测试京广线列车和地脉动作用下良乡塔东西向和南北向的振动响应,并建立结构的ANSYS有限元模型,通过现场测试与数值模拟,分析良乡塔的自振频率、振型以及列车影响下结构的振动速度最大值,并对列车影响下结构的振动响应进行评估。结果表明:在两个水平方向上,良乡塔的前3阶自振频率相近,第1阶振型均呈弯曲型,第2阶、第3阶振型均呈弯剪型;列车激励下良乡塔各层楼面处的振动速度峰值在东西向4层变化较大,从1层到顶层整体呈轻微减小-增大-减小的趋势,在南北向总体呈缓慢增长的趋势,最高承重结构处的振动速度峰值为0. 053mm/s,对古塔的完整性和安全性影响较小。此研究方法可为相关古塔的研究提供参考,研究结果可为良乡塔的后续疲劳寿命研究提供数据依据。

Research on vibration law of ancient pagoda in Liao dynasty based on dynamic characteristic analysis under train excitation

Taking the Liangxiang pagoda of the Liao dynasty in Beijing as the research object, the vibration responses of the east-west and north-south directions of the pagoda under the trains on the Beijing-Guangzhou line and ground pulsations was tested, and the ANSYS finite element model of the structure was established. Through the field test and numerical simulation, the vibration frequency, vibration mode and the maximum vibration velocity of the structure under the influence of the train were analyzed, and the vibration response of the structure under the influence of the train was evaluated. The results show that: the first three natural frequencies of the Liangxiang pagoda along two horizontal directions are similar. The first stage vibration mode is bending type, and the second and third modes are bending and shearing type. The peak value of vibration velocity of each floor of Liangxiang pagoda under the influence of train varies greatly at the fourth floor in the east and west direction, showing a slight decrease-increase-decrease trend from the first to the top floor. And there is a trend of slow growth on the whole in the south-north direction. The peak vibration velocity at the highest load-bearing structure is 0. 053mm/s, which has little effect on the integrity and safety of this pagoda. This method can provide reference for the study of ancient pagoda, and the results can provide data basis for the study of the later fatigue life of this pagoda.