基于压力变送器的主梁挠度监测系统动态性能研究

为研究基于压力变送器的竖向位移监测系统进行动态位移监测的适用性,以桥梁健康监测中常用的主梁挠度监测系统为对象,采用正弦波位移加载方式,研究影响监测系统位移振幅比的因素,并根据一阶系统传递函数分析其时滞常数和幅频曲线。结果表明:水管长度、水管材质、水柱高度、位移幅值对位移振幅比的影响很小,加载频率是主要影响因素;时滞常数随被测点竖向位移动态频率的增大而增大,频率不大于0.2Hz时,时滞常数可按13.3s取值;要求振幅比不小于0.95时,频率不应大于0.025Hz。

Study on Dynamic Property of Monitoring System of Main Girder Deflection Based on Pressure Transmitter

To study the applicability of a vertical displacement monitoring system based on pressure transmitter for monitoring the dynamic displacement, taking a monitoring system for monitoring the deflection of main girder which is commonly adopted in bridge health monitoring (BHM) as an object, we investigated the influence factors on amplitude ratio of the monitoring system by adopting a sinusoidal displacement loading method. Moreover, we analyzed the time-lag constant and frequency-amplitude curve according to the transfer function of a first-order system. The results show that the predominate influential factor is loading frequency, and other factors, such as pipe length, pipe material, water column′s height and displacement value, have limited effects. The time-lag constant will increase as the dynamic frequency of vertical displacement at the measured spot increases. When the loading frequency is not higher than 0.2 Hz, the time-lag constant can be taken as 13.3 s. The loading frequency should not be higher than 0.025 Hz when the amplitude ratio is not less than 0.95.