Analysis And Measurement Of The Dynamic Characteristic For Bridge Structure With Wireless Sensor Network

Structural health monitoring is a revolutionary method of determining the safety situation of structures. A considerable long period is often required for conventional investigation, which needs the structure has to be shut down for months. However, with the great development of sensor technique, Micro-Electro-Mechanical Systems, modern network technique and wireless transmission technique, a new method which is based on wireless sensor network technology is applicable for obtaining structure health and performance information.with the background of the applications of Imote2 wireless sensor node technology, an introduction about the health monitoring system of bridge, wireless sensor network system and node, including the definition, constitution and work description was presented in this thesis. Modal analysis which is one of the post-process methods is also studied and a new method for distinguishing the different mode frequencies based on Stochastic Subspace Identification and Natural Excitation Technique method is discussed. Then an applicable computer program based on the NExT/SSI theory to identify the dynamic characteristic of a structure was developed. The commercial FEA software ANSYS10.0 is used to rectify the NExT/SSI theory. In the modeling, Gauss white noise load is used to simulate the environment oscillation. The simulated dynamic response is analyzed to distinguish the different mode frequencies and mode shape with present porgram.The wireless sensor network system technology is applied in the experiment of a truss bridge model and ZhanJiang bay bridge which is a steel-box girder cable-stayed bridge with a major span of 480m. Comparison analysis of the results using NexT/SSI method and Eigensystem Realization Algorithm (ERA) rectify that the wireless sensor network technology is applicable and useful in health monitoring and mode analyzing of bridge.The result from this thesis about the wireless sensor network and stochastic subspace identification (SSI) algorithm may present some valuable and helpful reference and guidance in analysis of structural dynamics.