Study On Vehicle Load Identification Method Based On Bridge Structure Response

Vehicle load is the most important dynamic load on the bridge structure,which is the main factor leading to fatigue damage and structural reliability reduction of the bridge structure.Accurately grasping the actual dynamic load level of the bridge structure under operating conditions is the most urgent and significant link at the moment.In this paper,two new methods based on the shear strain influence line are proposed to identify single vehicle loads,and the lateral distribution of loads is also considered.According to the characteristics of the shear strain influence line,not only the axle weight and the vehicle weight can be identified,but the vehicle speed and the wheelbase can be identified.The first method uses the principle that the mutation value of shear influence line is proportional to the magnitude of load to identify the moving load.This method needs the abrupt change of shear strain influence line of each main beam to calculate the vehicle weight.The second method uses the linear characteristic of shear influence line of simply supported beam and the principle that the magnitude of load is proportional to the slope of influence line to deduce the common principle of identifying moving loads in time domain.The method needs to estimate the vehicle speed and the slope of the shear strain influence lines of the main girders to calculate the vehicle load.In order to verify the correctness and feasibility of the two methods,the ANSYS software is used to establish the solid model of simply beam bridge for numerical analysis.The vehicle weight is simplified to multiple concentrated loads,and the recognition effect of different vehicle working conditions on different lane working conditions is analyzed.The bridge surface roughness and noise resistance is analyzed based on the method of shear strain influence line slope.Mainly got the following conclusions:(1)Both methods have higher accuracy in identifying the total weight of the vehicle regardless of the vehicle operating conditions in any lane position.(2)When the axle load are identified by the mutation value of shear strain influence line,the identification value of the front axle weight is usually smaller than the actual value;the rear axle weight identification error is more accurate.The method has high recognition accuracy without external interference and has certain referencevalue for vehicle information recognition.(3)When the slope of shear strain influence line is used to identify the total weight of vehicles,the recognition accuracy is high in different speed conditions,bridge deck irregularity conditions and noise resistance.The method has strong anti-interference ability,and the recognition effect on single vehicle load is good undervarious working conditions,and the feasibility is high.