频率法测短吊杆索力测量方法的比较分析

Comparative Analysis on Measurement Methods of Short Suspender Tensile Force by Frequency Method

以湖南益阳康富南路跨线桥为实例,对其吊杆索力分别采用DASP动态采集分析系统和JMM-268索力动测仪进行测试,从而比较两种频率测量方法用于短吊杆索力测量的优劣。通过实例比较得知,DASP动态采集分析系统更适宜短吊杆索力的测量,其精度比JMM-268索力动测仪高。以弦振动理论为基础的振动频率法是桥梁健康检测中检测索力的一种常用间接方法。由于系杆拱桥的吊杆比较短,且吊杆索力受两端约束条件影响比较大,根据本例实际考虑了短粗拉索的抗弯刚度,采用边界条件为两端铰接拉索的自由振动进行分析,建立由频率识别拉索索力的近似公式。

Taking the KangFu South Road Overpass in Yiyang city as an example, the suspender tensile force was tested by DASP dynamic collection and analysis system and JMM-268 cable force vibration measuring device, respectively, in order to compare the two frequency measurement methods. The comparison results showed that the DASP dynamic collection and analysis system has higher precision compared with the JMM-268 cable force vibration measuring device, which is more suitable for the measurement of short suspender tensile force. Vibration frequency method is based on the theory of the string vibration, which is the conventional indi- rect testing method of cable force in bridge health detection. The suspender of bowstring arch is short and the both ends constraint conditions have great impacts on boom cable force. In the case study, the flexural rigidity of stubby guy cable was considered and the boundary conditions was adopted to analyze the free vibration of both-end hinged cable, and the approximation formula to obtain cable force from frequency was established.