The Research Of Multi-order Frequency Method Of Identification Of Cable Parameters And Development Of Wireless Monitoring System Of Cable Force

Cable structures has been more and more widely used in the construction of modern cities, due to many of their advantages such as the strong overall stiffness, rich modeling, light weight, convenience of transportation and construction etc. The cables are very important component of cable structures, thus the state of stress of cables concerns the safety in construction and normal service of cable structures. Therefore it has very important practical significance to monitor the force of cables of cable structures exactly in real-time.Frequency method is the most economic and practical method in engineering practice. It has been widely used in the field of large span cable-stayed bridges, with high accuracy. The numerous cables in cable structures have different specifications and have complicate conditions of support. Thus it has higher requirements on the timeliness and generality of method of measurement of their internal force. This paper researched the multi-order frequency method of identification of cable parameters, developed the wireless cable force monitoring system, depending on the wireless sensor network.First, this paper researched the multi-order frequency method of identification of cable parameters, which is the core algorithm of cable force calculation in the system, considering the disadvantage of traditional method of cable force calculation. This paper summarized the frequency equation of different cable computation model, then identified multi parameters of cable such as cable force and flexural rigidity or boundary constraint stiffness using the genetic algorithm. This paper provided the detailed process of program realization of the algorithm, and confirmed the high accuracy of the algorithm using several numerical examples. This paper also expounded the process of identification of cable parameters based on finite element method, which was used as the compensation method of cable force calculation in the system.Then this paper expounded the development of the wireless monitoring system of cable force. The system combined the acquisition of acceleration, the transportation of digital signal, the frequency analysis of signal, and the calculation of cable force. Meanwhile, the system has practical functions such as storage of engineering information, visualization of structure model and measuring point and graphic display of results, for more convenient management of monitoring works. The hardware foundation of the system was briefly introduced. The function of each module, the workflows and compilation principle of software were introduced in detail.Finally, this paper tested the stability and accuracy of frequency measurement of the system through an indoor test of the tension measurement of steel stranded wire This paper also discussed the influence of different places and different fixed forms of sensor on the result of frequency measurement. The system was used in the internal force measurement of steel tie rods in a reduced scale structural model of steel structure of a stadium. The system was also used in the cable force measurement of a stadium’s mast stay-cables, with good results.