Research On Security Early Warning Method Of High Speed Railway Bridge Based On Vibration Monitoring

As high-speed railway develops rapidly,it calls for fully qualified bridge to carry fast-moving trains,however,it is difficult for us to detect the bridge's performance changes as well as to identify the structure damages,both of which are important for engineers to manage the bridges correctly.Structural health monitoring system of the long-span bridges for ensuring bridge structural safety,applicability,durability provide a good platform.With the accumulation of real-time monitoring data,effective analysis and processing of large health monitoring data,the relationship between the establishment of environmental effects,the traffic load and the output state of bridge structure enhance the level of design and analysis of the bridge structure, which is the important field of health monitoring.The reserach object of this paper is Nanjing Dashengguan Yangtze Bridge in Beijing-Shanghai high speed way. This paper focuses on the dynamic response characteristics of bridge under the action of train load and environmental effect based on long-term monitoring data.Based on vibration monitoring,the early warning method is established. The main work in this paper is as follows.1. Based on the vibration data of Dashengguan Yangtze Bridge under train load, by empirical mode decomposition method (EMD), original vibration monitoring signals is effective filtered.Through detailed investigation and analysis of beam amplitude under train load, peak acceleration of long-term history analysis, and correlation of train speed and emperature of structure.2. Based on the vibration data of Dashengguan Yangtze Bridge under the influence of temperature, the dynamic response of structure is analyzed in detail. Researches mainly contain correlation analysis between amplitude of steel truss arch girders and structural temperature and correlation analysis between peak acceleration of girders and structure temperature. Long-term structural modal frequency monitoring results is accurately identified through the information fusion technology. And correlation between the modal frequency and structure temperature is analyzed.3. Based on the monitoring data analysis, two kinds of safety wanring methods based on vibration monitoring data are established:(1)using the envelope diagram of correlation between the train velocity and acceleration extremum,dynamic response to early warning method under the train load is established.(2) through the contrast analysis of numerical simulation results and the measured results, the influence of environmental temperature on the modal frequency of the structure is discussed. Using control charts for arithmetric average,abnormal warning indicators of structural modal frequency variation are established.