Vehicle Loads Identification Of Simply Supported T-beam Bridges Based On Vehicle-bridge Coupling System

Vehicles and bridges are very important components of highway transportation system.In the vehicle-bridge system,moving vehicle load is one of the main reasons for fatigue,durability reduction and damage of traffic infrastructure such as bridge structure.On the other hand,in the long-term bridge monitoring,it was found that the identification of dynamic effect of moving vehicles across the bridge significant.Therefore,it is important to identify the dynamic and static loads of moving vehicles in vehicle-bridge system.In previous studies,the identification of moving vehicle loads was mainly based on the single-girder vehicle-bridge coupling system model.For the multi-girder bridge model,the identification of moving vehicle loads with single-girder vehicle-bridge coupling system cannot accurately reflect the coupling vibration characteristics of the vehicle-bridge system.In this thesis,a vehicle-bridge coupling vehicle loads identification system based on single beam method and grillage method was developed by using MATLAB software,which can effectively identify the moving vehicle loads on the simple supported single girder and multi-girder bridge models.The main researches of this thesis are as follows:1)This paper reviewed the state-of-art research of moving vehicle technology,and introduced the principles of single beam method and grillage method vehicle-bridge coupling dynamic analysis module in detail.2)The generalized orthogonal function approximation method and improved reduced system condensation method were used to establish the strain-based vehicle loads identification analysis system.And the bridge strain response was calculated through the vehicle-bridge coupling dynamic analysis module.Then the extracted bridge strain is used to identify the moving vehicles loads.3)A single girder bridge and three grillage models of simply-supported T-girder bridges(span: 20～40m)from “the general drawings of highway bridges and culverts(GDQ/ T-TL(S1)20/26.0-201403,2015)” were used to verify the effectiveness of the vehicle-bridge coupling identification system.The influence of key parameters such as speed,sampling roughness,frequency and noise on the dynamic load identification accuracy was analyzed.The accuracy of dynamic load identification between single girder and grillage model was compared.4)According to the identified dynamic load results,the static axle load and the total weight of the vehicle under different working conditions were calculated,and the error was kept within 10%.The error range was close to the error of the traditional Moses algorithm,but the Moses algorithm is generally applied to 5-15 m bridges.Compared with Moses algorithm,this method can be applied to bridges with longer span.