| With the continuous progress of China’s construction of a strong transportation network,highway-bridge construction is booming.But there are many new challenges,such as high speed,large load,high comfort and high safety.The healthy and safe operation of the bridge structure is the key to ensure the smooth passage of the main traffic arteries.However,accidents of bridge overturning and collapse caused by vehicle overload often occur,which poses a great threat to the safety of people’s life and property.Therefore,it is of great practical significance to accurately identify the vehicle load on the bridge,provide reliable load information for the bridge health monitoring system,timely find the overloaded vehicle and warn the interception,and ensure the safe operation of the highway bridge.Most of the existing long highway bridges are continuous girder bridges,but the research on moving load identification of continuous girder is relatively few.This thesis proposes a moving load identification method based on finite element method and data reconstruction and verifies the accuracy of the method by numerical simulation.The main research contents are as follows:Most of the existing long highway Bridges are continuous girder Bridges,but the research on moving load identification of continuous girder is relatively few.This thesis proposes a moving load identification method based on finite element method and data reconstruction,and verifies the accuracy of the method by numerical simulation.The main research contents are as follows:(1)Taking a two-span continuous beam as an example,the finite element method is used to deduce the motion equation of the bridge under the load of a two-axle vehicle,and the stiffness matrix,damping matrix and mass matrix of the bridge are obtained.The regularization method is used to deduce the load identification calculation formula.(2)The dynamic response calculation program of the continuous girder bridge under the load of a two-axle vehicle was compiled by MATLAB,and the same calculation model was established by ANSYS,and the dynamic response of the bridge under the two calculation methods was compared and analyzed.Chebyshev polynomial was used to reconstruct the displacement response.Based on the reconstructed displacement response,the Newmark method is used to reconstruct the velocity and acceleration response of the bridge.The reconstructed data were substituted into the calculation formula of moving load to identify the moving load,and the identification result was in good agreement with the real load.(3)The influence degree of bridge displacement,speed and acceleration response on load identification results is analyzed,as well as the influence of vehicle speed,load size and bridge span on moving load identification results.The results show that the displacement response has the greatest influence on the moving load identification results,while the acceleration response has the least influence on the load identification results.The identification error of moving load increases with the increase of vehicle speed and span number of continuous beam.The identification error of the first load(front wheel axle weight)is stable,while the identification error of the second load(rear wheel axle weight)is sensitive to the change of load size.(4)When two two-axle vehicles(i.e.,four moving loads)are acted on the continuous beam at the same time,the relative error between the identified load and the real load is very small.The error of load identification increases with the increase of span number of continuous beams.With the increase of vehicle speed,the identification errors of the four moving loads decrease first and then increase.The moving load identification results of the two vehicles are less affected by the size of the moving load. |
