The Study Of Vehicle Load Model For Highway Bridge Based On WIM Systems

Vehicle load is one of the main reasons of bridge’s fatigue damage and loss of endurance. In the severe cases it even brings about the collapse. The study of actual vehicle load model provides support not only to the assessment of bridge safety and reliability, but also to its maintenance and reinforcement. Even in the overload control, this study is also helpful. In general, the study of actual vehicle load has very important theoretical meaning and engineering practical value. This thesis takes the Xiabaishi Bridge on the national highway Shen-Hai line (G15) Fujian province FuNing expressway as the background, based on the weight in motion (WIM) systems of Xiabaishi Bridge. The method of establishing the actual vehicle load model is studied. The main jobs of this thesis contain follows:(1) The brief introduction of the installation and debugging of Xiabaishi WIM systems, and the statistical analysis of the data which is collected to get the vehicle load statistical distribution characteristics of each parameter.(2) Establishment of the vehicle load effect model of Xiabaishi Bridge based on the theory of Equilibrium Renewal Process and Quasistatic Generalized Influence Line, which then is verified according to the data of the health monitoring systemn, furthermore the comparison between the actual load effect with the effect in the code and the assessment of Xiabaishi Bridge vehicle load model(3) Comparison between the vehicle load effect of established vehicle load model with that in the design code of Xiabaishi Bridge (JTJ021-89) and the current design code (JTG_D60-2004),and the evaluation of the bearing capacity of Xiabaishi Bridge. The main conclusions of the study show as follows:(1) Gaussian function is suitable for reflecting the multi-peak distribution of the vehicle weight of each lane in the general state and the dense state. The statistical analysis of the vehicle weight of WIM system is consistent with the result of static weight system.(2) In the normal state, the gross vehicle weight and the axle load of the actual vehicle load on Xiabaishi Bridge follow the bimodal Gaussian distribution. The vehicle length of the passing lane follows the bimodal or trimodal distribution while that of the main driveway follows the multi-peak distribution. In the general state, vehicular gap follows the lognormal distribution, while in the dense state the gap follows the bimodal or trimodal distribution.(3)In different load recurrence period of Xiabaishi Bridge, the mid-span load effect of side and middle span both follow the extreme value distribution. The mid-span load effect (of section E) of middle span is more likely to go beyond load effect of the design code. In the load recurrence period of 10 years, the exceeding probability is 26.77%, and the amount of overload vehicles load can reach 20% in total.(4) The test and numerical analysis show that the actual vehicle load of Xiabaishi Bridge does not exceed the specification in design codes. Xiabaishi Bridge not only has the ability to bear the vehicle load of truck-20 and trailer-120 load, but also has the ability to support the Highway-I load.