Design On Full-Function Wireless Sensing System For Bridge Structure Monitoring

Large bridges play a significant role in both the construction of infrastructure and the national economy, and the security situation of the bridges draws people's attention widely. Because of long-term load and natural environmental influences, there are conditions like structural damage and excessive local stress in the bridges, which will affect the safety of the bridges. Therefore, it is of high importance to monitor the structure and to assess the security of the large bridges from the perspective of people's life and property safety. In the monitoring, many factors like the vibration of the bridge deck, local stress, cable force of stay-cable and suspension cable, the change of the dip-angle, and working environment should be concerned, in order to monitor and assess the safety situations comprehensively. Based on above, the full-function wireless sensing system which can monitor multiple crucial information of the bridges synchronously is developed in this thesis.Firstly, the existing problems and the basic principle of the wireless bridge structure monitoring system are analyzed, and based on the wireless sensor networks topological structure, the architecture of the overall system is designed. Moreover, the modular design of the sensor nodes including sensor unit, signal conditioning unit, microprocessor unit, storage unit, wireless communication unit and power management unit are introduced in detail, and the design of the embedded software and the data collection and management system are revealed. In addition, that time synchronization is of great importance to ensure the validity of the data analysis of bridge structure monitoring is illustrated. So, the study of time synchronization is one of the important research content of this topic. In this paper, classic time synchronization algorithm in the wireless sensor networks is discussed, modified time synchronization algorithm LP-TPSN that can reduce energy loss in the process of time synchronization is proposed, and simulation verification is finished. Finally, the calibration experiment of the sensors and actual measurement of the bridges are examined.The study shows that the fully-function wireless sensing system based on wireless sensing network technology can monitor various key information of the bridge structure synchronously, quickly, and conveniently, and that this system can provide complete and reliable basis for the assessment of the security condition of the bridges, and it has a wide application prospect and practical value in the field of bridge monitoring.