Operational Safety Assessment Of Rail Transit Bridge Based On Monitoring Data Analysis

There are some different degrees of diseases in viaduct of rail transit line on account of the perennial heavy operation,which affect the operation safety and passenger comfort.Therefore,evaluating the health condition of the viaduct in rail transit line exactly and timely is extremely essential,only in this way can we guarantee the safety of rail transit operational.Based on the National Key R&D Program of China from Beijing Metro Operation Co.Ltd,this paper research on the representative bridges of three types of urban rail transit lines in Beijing by using statistics and vehicle-bridge coupling vibration theory and big data analysis,simulation and other technologies,in order to put forward a kind of operation safety evaluation scheme for the bridge of urban rail transit line.The main work is completed as follows:1.The research status of health assessment of urban rail transit bridges at home and abroad is summarized in detail,it make the research direction of this paper more clear and work out the line of research technical and the anticipated results.2.The bridge health monitoring system was established on three selected representative bridges of different bridge types to realize the data acquisition,transmission and storage of stress,displacement,deflection and temperature.3.The collected monitoring data are preprocessed by Kalman filter and Lagrange interpolation,Wavelet analysis is used to analyze and identify the data in time and frequency domain,a variety of mathematical models are established to analyze and fit the correlation between the monitoring data and its main influencing factors with the help of data analysis software such as Origin and SPSS,the main factors affecting the monitoring indexes and their correlation with the corresponding indexes were found out.4.The vehicle-bridge coupling simulation model was established to simulate the bridge response caused by the change of ambient temperature from-25℃ to 40℃ without or with vehicle load,and the bridge response caused by the change of vehicle speed from 70-160km/h when the temperature was maintained at 25℃.The test data and the simulation data are compared to verify the dependability of the test data and the accuracy of the simulation date,and the data analysis conclusion is further verified.5.According to data analysis and simulation results,combined with relevant norms and standards,the dynamic warning threshold and scoring standard of each test item are given by means of mean control chart and BCI scoring mechanism,the main frame and evaluation process of the bridge health condition evaluation system was put forward,the development and debugging of the system are realized by cooperating with the software company.The results show that:(1)The monitoring indexes of the three typical bridges are all affected by temperature and train load,and the temperature is the dominant factor affecting the monitoring indexes,while the train load has a relatively small effect.(2)The monitoring indexes have obvious correlation with temperature,among which the bottom stress of the mid-span beam is positively correlated with temperature,the steel-concrete interface relative displacement of steel-concrete composite beam bridge is inversely proportional to the ambient temperature,it is positively correlated between the longitudinal displacement of beam and temperature.(3)Speed and vehicle-bridge coupling dynamic effect have no obvious influence on the monitoring indicators,so the current speed is relatively safe and has a certain space for speed increase.(4)The system evaluation results show that the three typical bridges are in good operation condition,and the bridge has slight damage but can meet the safety requirements of daily operation,as long as the routine maintenance is maintained.(5)The evaluation system has a certain universality,and some of the parameters need to be adjusted according to the results of operation and debugging and the realistic bridge condition,which can can be used for reference to research of bridge health monitoring and evaluation in the future.