Research On Health Monitoring And Condition Assessment For Anlongquan Interchange Overpass

Bridge is the throat of the modern transport networks, and plays an important role in thepeace and stability of a country, the development of the economy, the culture communicationas well as the consolidation of the national defense. With the higher demand of the moderncity transportation, as well as the advent of the various high-tech materials and high-techtechnologies,"the long bridge lying on the water wave","the road weaving in the air"become to reality. However, due to the bad natural working environment of the bridge, andthe building materials are influenced by environment and the time variation, as well as otheradverse effects of human factors and accidental factors. Many bridges often occur structuralfunction degradation, structure damage or even the structure collapse before they reach thedesign service life of the structure. In recent years, China’s frequent bridge collapse accidentraised the public awareness of the bridge quality, even brought a lot of doubt to the bridgeconstruction quality as well as the construction technique of our country, at the same timebrought China’s booming bridge construction career into a hazing.Considering the bridgecollapses would bring great economic losses and serious threats to the lives and properties ofthe people, as well as be a disaster to the already congested urban traffic.The municipaldepartment of a city formulated that the municipal bridges must be detected every year inorder to keep the bridges in a safe condition, but the bridge detection will cost a lot of moneyand need to block the traffic, even this a bridge can be tested only once a year, not achievingthe real-time monitoring for the health condition of a bridge. Therefore, developing areal-time monitoring system for the health condition of municipal bridges is imminent.This paper based on the traffic science and technology project "Research on the healthmonitoring technology for Anlongquan interchange overpass in national highway102"(contract number:2009-1-24) of Jilin province, the specific researches in this paper are asfollows:1. Making a comparing research between the fiber bragg grating sensors and thevibrating wire sensors which are very widely used in the field of engineering in this current,analyzing their respective principle, characteristics and the ranges of adaptation. Accordingto the actual situations of bridges in Changchun area as well as the specific situation ofAnlongquan interchange overpass, choosing sensors which could satisfy the request of the long-term health monitoring for bridge structure for50years or more.2. Laying out distributed optical fiber grating sensors and integrating the monitoringsystem, forming the real-time monitoring system of Anlongquan interchange overpass.Incombination with the computer networks, design four kinds of data transmission systemwhich are able to achieve the data remote transmission, and suitable for Anlongquaninterchange overpass specific situation. That is the data transmission system based on LAN,the data transmission system based on LAN and the VPN technology, the wireless datatransmission system based on the3G wireless network and LAN as well as the VPNtechnology, the wireless data transmission system based on GPRS/GSM, with which couldachieve the remote real-time transmission of the monitoring data in all situations.3. Using the bridge finite element analysis software Midas/civil build the bridge finiteelement model, through analysising the stress response under various operating conditionsbased on the model, combined with the measured data, and finally put forward the bridgestress threshold, the threshold is the warning value of the bridge bearing, when the measureddata is greater than the threshold, then the system automatically alarm.4. Conducting a thorough research to the theory of the bridge condition assessmentbased on the Fuzzy Analytic Hierarchy Process (FAHP), designing the hierarchical conditionassessment model of the bridge as a whole. Use the fuzzy multi-level comprehensiveevaluation methods achieving a reliable assessment for the bearing capacity and the safetyperformance of a bridge under the static force as well as the dynamic force.The Anlongquan interchange overpass health monitoring system established in thispaper is the first time using fiber bragg grating sensing instrument in Jilin province realizingthe remote real-time monitor of the city overpass bridges, and is the first time to achieve theremote real-time monitor of municipal bridges in the northeast high-cold region of thenortheast. Through the obtained dynamic real-time data, the department in charge of theAnlongquan interchange overpass can monitor the health status of the bridges at any time.The accumulated data would have a very important guiding significance to the bridgemaintenance and repair, and to optimization design for bridges in the northeast high-coldregion of northeast as well as high-cold region of the world in the bridge industry.