Danamic Characteristics Of Cable-stayed Model Bridge Based On Wireless Sensors Networks

This thesis studies dynamic characteristics of a cable-stayed bridge modelbased on wireless sensors networks (WSNs) with identifying the modal paremeters,which are in comparison with that from traditional wired sensors, and this scalemodel comes from Binzhou Yellow River Highway Bridge located in Shandongprovince, China. This thesis is a basis study in order to extend application of WSNsto bridge structures dynamic monitoring, and the detailed contents of thisdissertation are shown as below:Firstly, this thesis gives a test scheme and builds a vibration system composedof an excitation subsystem, an aqusition subsystem and an analysis subsystem withconsidering of mostly making use of the own instruments and apparatus inlaboratory. Multipe Input and Multiple Output test scheme play a part in vabritionexperiment based on Operational Modal Analysis, and Moving-Reference pointsmethod is used to measure. The excitation system and the aqusition systmen buildedin wired sensors use the Virtural Instrument instead of some traditional apparatus,and Virtural Instrument software development platform is LabVIEW8.6. In WSNs,the Imote2node platform and corresponding ISM400sensor board are used. Theanalysis system uses MATLAB software to accomplish the data processing.Secondly, this thesis studies Operational Modal Analysis in which onlyresponse outputs are kown based on modal test and Finite Element Analysistechnology. It understandes theories of both Eigensystem Realization Algorithm andFrequency Domain Decomposition, and their MATLAB computational programs isused to identify the dynamic characteristics parameters of bridge models, the firstsix vertical shapes and frequencies of the deck, using the aquired accelerations fromvibration symtem in wired above.With contrasting to frequencies and normalizedmodes from different algorithms, the MATLAB programs are proved to beright.Two Longitudinal Spines method is choosed to similate the bridge model inlaboratory in order to identify the first six vertical shapes and frequencies of thedeck prior to vibration test.Thirdly, The accelerations from wireless sensors network acquisition system are programmed to identify modal shapes and frequncies, which is consistent withthat identified in wired. It means that wireless sensors network based on Imote2node platform can be employed in application of bridge model dynamiccharacteristics analysis.With the same identified shape from both wired and wirelessaccelerations, the maximum difference of frequency is3.41%at the first verticalshape and the second is2.26%at fifth, others are less than1%. The dynamiccharacteristics of bridge model are shown as below: its modal is intensive, verticalmode stiffness is weaker than transverse and the ratio of torsion to vetical mode is2.77.