Study On Load Model Of Bridge Vehicle Load Effect Based On The WIM Data

Vehicle live load is the main load that a bridge hears during its service.It is also one of the main reasons for fatigue failure of bridges.The analysis and study of the load situation of the current vehicle in the bridge can provide the accurate basis for the design of the bridge,the maintenance and reinforcement and the reliability evaluation.Our country has a vast territory,and the economic development is quite different.The loa.d of vehicles is positively correlated with the degree of economic development In addition,the load effect of bridge in actual operation is also different from the design specifications.Therefore,the standard model cannot meet the requirements of load bearing in different regions and time periods.It is necessary to establish load models based on actual vehicle data.Vehicle load effect is a random variable,Many scholars put forward a variety of vehicle load effect models based on this.With the progress of the technology,the dynamic weighing system(weigh-in-motion system,WIM)data can be used to study the extreme value variation of vehicle load effect more accurately,and predict the extreme value of the vehicle load effect in the future period.The research shows that vehicle load effect is mainly represented by multimodal distribution,and the fitting error is large with a single distribution function.In this paper,the existing research results are summarized.On this basis,a POT(peaks over threshold)model based on the generalized Pareto distribution(generalized Pareto distribution,GPD)is proposed to describe the distribution of the vehicle load effect samples,and then the extreme value of the design reference period is obtained.In this p aper,the WIM sy stem dat of a 111 day expressway taken as the sample,and the load effect model of the bridge vehicle is set up,and the load effect standard value is extrapolated in the design datum period of the bridge,and it is compared with the current standard.Study on the vehicle load effect model is divided into three main steps in play:(1)Monitoring the actual traffic volume of the existing bridge and analyzing the monitoring data.(2)According to the traffic flow data,section distribution calculation of load effect.(3)According to the section distribution calculated by extrapolation,load in the design reference period effect standard value.The research process of this paper mainly includes the following work:(1)Summarizing the research status at home and abroad,and studying the existing highway bridge load effect specification.(2)The introduction of extreme value theory and the tail data fitting of the load effect sample based on the POT model of the generalized Pareto distribution(GPD),set up the vehicle load effect model reflecting the actual traffic situation of the bridge,and extrapolated the standard values in the 100 year datum period.(3)The results obtained by extrapolation are compared with the standard values of General code for design of highway bridge and culverts(JTG D60-2015).