基于频率法的吊杆索力测试及影响因素研究

Research on Cable Force Measurement and Influencing Factors of Suspender Based on Frequency Method

下承式拱桥吊杆索力的精确测试与控制是当下业界研究的热点,文章以衡水衡武大桥(90m跨下承式钢拱桥)施工中吊杆索力测试为例,采用基于弦振动理论的频率法测试吊杆索力,并对影响测试精度的因素进行探究。结果表明:对于边界约束,可以通过修正吊索的计算长度来消除其影响,得到了索长修正公式;对于抗弯刚度,当衡武大桥吊索长度小于13m时,抗弯刚度对索力测试的影响较大,此时索力的计算应考虑抗弯刚度的影响;同时根据算例分析可知,实际应用中抗弯刚度对索力测试影响的大小还与设计索力值相关,不同的设计索力值对应的最小索长亦不同。研究成果可为拱桥建设与运营中索力检测提供技术参考。

The precise test and control of the cable force of the down-supported arch bridge is a hot research topic at present.In this paper,taking the suspension rope force test in the construction of Hengshui Hengwu Bridge(90m span under-bearing steel arch bridge)as an example,the frequency method based on string vibration theory was used to test the suspension rope force,and the factors affecting the test accuracy are explored. The results show that for the boundary constraint,the influence of the cable length can be eliminated by modifying the calculated length of the sling,the cable length correction formula is obtained;for the bending stiffness,when the length of the suspension of the Hengwu Bridge is less than 13m,the impact of the bending stiffness on the cable force test is greater and the calculation of the cable force should consider the influence of the bending stiffness;at the same time,according to the case analysis in practical applications, the influence of flexural stiffness on the cable force test is also related to the design cable force value and the minimum cable length corresponding to different design cable force values is also different.The research results can provide a technical reference for rope force detection in the construction and operation of similar arch bridges.