Structural Health Monitoring System Study And Application Of Jingyue Bridge

With the incrensing of the Chinese comprehensive national strength, more and more investment has been put into the national infrastructure, which immediately prompts our highway and railway great-leap-forward development. In recent years, as the connection hub of the traffic network, the bridges achieve a rapid unprecedented development, which brings the great fame for China in bridge field. However, the health of the bridges is usually influenced by the traffic load, human action and environment load, which cause the bridge diseases occur. The unscientific maintaining and monitoring for bridge, not only influences the safety of the traffic, but also reduces the bridge operational life. Consequently, the strucutural health condition has great significance to the safety and maintenance of the bridge.The bridge health monitoring is a nondestructive test means, which can provide evidence and guidance for operation and management of the bridges. The bridges health monitoring has gone through a long process of development so far from been put forward by related scholars. Some techniques, namely, detection, data processing methods and structural condition assessment theories have been continuously improved. Although the emergence of optical fiber sensing technology promoted the development of bridge strucutural health monitoring. Some deficiencies that may influence the system efficiency and reduce the actual use effect still existed, such as the detection technology of the key parameters of the bridge structure, seamless integration technology, the engineering implementation method of monitoring system, the expert system of structural condition assessment and so on.This paper takes the Jingyue Bridge as background, considering the bridge structural characteristics, a structural health monitoring system was built. Through the risk analysis of the structure, the key parameters and corresponding detection methods were determined. Based on optical fiber transmission network, large scale multi-parameter sensing network of Jingyue Bridge was designed and put into effect. The seamless integration techniques for different sensing parameters ensured the real-time acquisition, transmission, storage and analytical processing of the safety information of the bridge. The designed bridge health assessment expert system and practical C/S and B/S hybrid software system construction, realized the establishment of a complete, practical, availability, long-term health monitoring system.The main research work as follows:1. This paper stated the significance of the bridge structural health monitoring, the study and developed status of the health monitoring at home and abroad and some critical issues. Combined with the structural features of the Jingyue Bridge, the bridge structural health monitoring system has been built, and test items, signal network structure, computer systems and application systems have been planed.2. On the basis of analyzing the structure and principle of the existing FBG vibration transducer, a new type of FBG vibration sensor and its structure and principle has been studied.3. Based on the advantage of optical fiber sensing technique, a long-term online testing method for the bridge prestressed cable force was researched in this paper and the quantitative assessing method feasibility for the loss size of prestress for prestressed concrete continuous beam bridge during operation was verified by pratical engineering application.4. The cable of cable-stayed bridge performed a vital loading role, and also, is a major diseases area. So it is significant to develop cable testing technology research for evaluating the loading capacity, analyzing the disease extent and providing maintenance strategy. This research combined the optical fiber sensing technology with fabricating cable progress, and put forward a smart cable structure with embedding optical fiber sensors, which was verified by construction and operation testing data.5. Based on the risk analysis of the bridge, structural health monitoring system for Jingyue Bridge which adopted optical fiber sensing technology has been built. The system monitoring index included:the bridge load, the structure static response, structural and dynamic characteristics and some other safety information. The system integration technology for software and hardware was studied and a long-term structural health monitoring system with multi-parameter was designed and accomplished.6. Described the meaning and importance of the structural safety threshold and gave the threshold setting for every sensor parameter by finite element modeling simulation. The variable weight of analytic hierarchy process used to assess the strucutural safety for Jingyue Bridge was introduced. Several key techniques for engineering construction were summarized. Based on some actual data analysis, the main software functions were presented.