Research On Wireless Sensor Technology Applied In Bridge Structure Health Monitoring

With the increasing number of big bridges as well as the complication both in its style and functionality in recent years, monitoring bridge structure health, as one of the valid measure method to ensure bridges'structural safety, is a key issue to be taken into account in academic and engineering fields at home and abroad. The system of bridge structure monitor structure health using wireless sensing will reduce the construction cost, shorten the installation period and raise the system reliability. Furthermore, the further development of wireless communication, sensing and signal processing technology has prompted the application and generalization of wireless sensing technology in monitoring bridge structure health. At present, the bridges structure health monitoring system based on wireless sensing is still developing. So it's of great significance in research and economy to develop the wireless sensor applied in the bridge structure health monitoring. The thesis mainly focused on wireless sensing technology applied in bridges structure health monitoring system.In terms of the composition of the bridge structure health monitoring system and the bridge global performance requirements, the intelligent wireless acceleration sensor suitable for the operational bridge at a low frequency has been developed by module method in this thesis. The spot tests carried out on the Tianjin Yonghe Bridge demonstrated that the sensor identified accurately the vibration frequency at the range of 0 to 50Hz. The resolution of the sensor is up to 0.25mg and the wireless transmission distance reaches 450m, potentially high, which satisfies needs in monitoring the bridge structure health.For monitoring the local strain of bridge,the thesis emphasizes on the design of circuit to exciting coil and inspection circuit of wireless vibrating wire sensor by analyzing the mathematical model of the vibrating wire strain sensor and its working principle. The surface-sticked wireless-based vibrating wire strain sensor has been developed on the basis of the result. The experiments on the concrete beam under the condition of static loads have been carried out in the lab. The cross-comparison with the results acquired by the wired-based strain shows that the sensor satisfies the needs in monitoring the bridge strain. The sensor developed takes the advantages over in terms of interference-insensitiveness.