Dynamic Modeling And Load Limiting Analysis Of Highway Bridge Car Loads Based On WIM Data

The load model of highway traffic flow is the basis of the checking calculation of road and bridge structure design and safety evaluation.Due to the significant space-time evolution and difference of traffic flow load,the establishment of an accurate and representative load model depends on the grasp of the space-time evolution characteristics and laws of traffic flow load.In order to obtain the space-time evolution characteristics and regular model of vehicle load on Expressway,the distribution characteristics of vehicle type,headway,vehicle weight and vehicle speed on different lanes of multiple expressways are statistically analyzed based on WIM data,and the extreme value of vehicle weight on different lanes is extrapolated based on the extreme value theory to further analyze the load effect.The correlation analysis theory and spectral analysis method are used to study the time correlation of data,and the time evolution characteristics of high-speed traffic flow in different lanes are obtained.Finally,according to the vehicle load dynamic model,the vehicle flow parameters are extracted,the dynamic vehicle flow model is compiled,and the load limiting coefficient of 30 m simply supported beam bridge under the action of the vehicle flow model is calculated.The research shows that: in space,the probability distribution of vehicle types in each lane is different.The vehicle types of one-way 2-lane expressway have obvious two-layer distribution probability.The selection probability of3-axis and above vehicles on the slow lane of one-way 3-lane expressway is higher than 0.4,while the selection probability of 2-axis vehicles is about 0.15.The lateral distribution of vehicle weight meets the law of increasing from the inner lane to the outer side.The average vehicle weight of the same model on the slow lane is about 1.3-2.0 times that of the fast lane;The probability density distribution of vehicle weight in slow lane is characterized by thick tail and long tail,while that in fast lane is unimodal.The extrapolation results of load effect extreme value show that the bending moment effect of slow lane is about 1.3-1.4 times of that of fast lane and 1.1-1.2 times of that of middle lane,and the bending moment effect of midspan increases from the inner lane to the outer lane;The vehicle load lateral reduction coefficient of multi Lane expressway is higher than the standard value.In terms of time: with the extension of time,the autocorrelation of vehicle flow parameters gradually weakens,and the time autocorrelation of one-way 2-lane expressway is higher than that of 3-lane expressway.Taking the week as a continuous period,the measured traffic volume,vehicle speed and vehicle weight of different expressways are analyzed by spectral analysis method to show that the parameters have significant time period and spatial similarity.In terms of time,each parameter shows a decrease increase decrease periodic change,with a period of about 24h;Spatially,the amplitude of the same parameter has a lateral distribution difference in the inner and outer lanes.The calculation results of the load limiting coefficient of the simply supported beam under various working conditions show that the value of the load limiting coefficient of the simply supported beam section under the dynamic traffic flow model is equivalent to that of the actual traffic flow,and greater than that under the load of the design code.This paper deeply analyzes the variation law of each parameter of traffic flow on different lanes,further extrapolates and predicts the load extreme value and its load effect difference of different lanes in typical areas,and excavates and extracts the distribution characteristics and evolution law of traffic flow and load in time and space.The results are helpful to understand the spatial-temporal evolution characteristics of vehicle load,and provide a clear theoretical basis for the vehicle flow load model to reasonably consider the spatial-temporal evolution of vehicle flow.