Investigation Statistics And Simulation For Random Traffic Loading Of Expressway Bridge

The investigation of the traffic loading are the basis on which the following studies such as the designed loading, the time-variant bridge reliability analysis, the life expectation of the existing bridge, the ultimate capacity calculation and the random traffic flowing simulation are based. With the rapid development of the vehicle industry and the transportation business, a major change has occurred on the traffic loading, and the expressway have gradually play more and more important roles than the roles that the national highway and province highway had played before. However, the traffic loading investigation for the expressway is just on the preliminary stage, and there is few related studies. Therefore, it is rather important to conduct a real time and extensive investigations on the traffic flowing of a real expressway for this study in that most of the related characteristics of the traffic flowing as well as the related key parameters can be captured.In this thesis, With the collected traffic loading data from one bridge of Xi-Bao expressway, the stochastic characteristics of the related parameters of the traffic loading of the expressway are studied systematically and extensively, One moving loads identification approach for the multi-girder bridge, based on the calibrated FEM model, is presented. Then another specified program is employed to create the simulated vehicle model so that all the stochastic parameters will agree well with the realistic ones. The main research contents and conclusions are as follows:1. A methodology, capable of investigating all the critical parameters of the traffic loading on the expressway, is presented. For this approach, the speed radar gun, the video recorder, and the dynamic strain tester are for the first time being employed in combination with manually recordering to detailed investigate the traffic loading on the expressway bridge. With this approach, the vehicle type, speed, traffic lane, the arriving time of the traffic and the bridge-vehicle dynamic interaction are all recorded. Then based on the captured traffic loading samples within 24 hours, through the detailed analysis, the statistic distribution features and the variations of all the data listed previously with time are obtained, then the parameters database for the traffic loading is built。2. Aimed at batch identification of vehicles weight parameter, the collected data with regard to the dynamic displacement response to the traffic loading is statistically analyzed and classified by vehicle type, then the dynamic response characteristics of bridge subjectd to each type of traffic loading is obtained. 3. The analytical methodology governing the vehicle-bridge interaction analysis for the multi-girder bridge is introduced, the related analytical modules is programmed. Then, an interface, the preprocessor and the postprecessor and the animation demonstration system are programmed as well. Finally, by a real example, the reliability and the efficiency of the modules are verified.4. Based on the calibrated FEM, the low pass filter and the vehicle-bridge interaction analysis program specialized for the multi-girder bridge,the moving loads identification method applied for the multi-gider bridge is presented. Compared with the real bridge loading test, it is substantiated that the proposed identification method is reliable and accurate. Finally by the use of such identification method, classified by the vehicle type, the transverse location and the vehicle weight parameter corresponded with each running single vehicle in this investigation is obtained, on the basis of which,the statistical analysis is conducted.5. One program is coded, specifically for the random traffic loading simulation for the expressway bridge, using Monte-Carlo numerical simulation method and Matlab. Comparing with the real traffic sample, the simulation made by this program is accurate and reliable.