Model Test Study Of Vehicle-bridge Coupling Vibration

With the development of China's economy and transportation industry,a large number of new bridges and new structures have emerged.At the same time,the problem of vehicle-bridge coupling vibration has become increasingly prominent.Scholars at home and abroad have conducted a lot of research on the subject of vehicle-bridge coupling vibration of highway bridges.The analysis methods are mainly numerical simulation methods whose reliability is fully demonstrated.Some scholars also carried out real bridge tests and model tests.The real bridge test has the characteristics of high cost,inconvenient test,difficult test result collection,and poor versatility.The model test has the advantages of easy operation,good economy,short test cycle and reliable test results.Model tests are suitable for obtaining consistency laws and verifying theoretical analysis methods.Therefore,this paper is based on the vehicle-bridge coupling vibration theory of highway bridges and existing vehicle-bridge coupling vibration analysis programs.A set of vehicle-bridge coupling vibration analysis test system for highway bridges is designed.Carry out experimental verification of the coupled vibration analysis method for automobile-bridge time-varying systems.Based on this,the law of influencing factors of vehicle-bridge coupling vibration tests on highway bridges is discussed.The main research contents are as follows:(1)Based on the vehicle-bridge coupling vibration theory of highway bridges,the vehicle-bridge time-varying system is divided into two subsystems: vehicle and bridge.The conventional finite element method is used to establish the bridge motion equation.Simplify the vehicle into a multi-rigid body system with springs and damping elements connected.A two-axis 11 DOF vehicle space model is established and its motion equation is derived.Considering the roughness of the road surface,the conditions of displacement coordination and interaction forces at the bridge contact points of the vehicle are used.And coupling the motion equations of the vehicle and the bridge subsystem.The step-by-step integration method is used to solve the vehicle-bridge motion equation,and the convergence criterion is formulated.Aseparate iterative method was used to obtain the dynamic response of the axle.Based on the above theory,the process of compiling the vibration analysis program for highway bridges and bridges using Intel Visual Fortran language is described.(2)The parameters such as the stiffness,damping of the test vehicle tire lateral,tire radial,rear vertical damping springs,front vertical damping springs,rear lateral damping springs and front lateral damping springs are accurately measured in the laboratory.Vehicle and bridge test models were made,and a vehicle-bridge coupled vibration test system was designed.The system consists of a vehicle test model,a bridge test model,and a test model power system.It can realize the test of the vehicle in the bridge test section with uniform speed,acceleration and deceleration.On this basis,the vehicle-bridge coupling vibration test analysis of highway bridges is carried out.The accuracy of the vehicle-bridge analysis program and the reliability of the vehicle-bridge coupling vibration test system are verified.(3)Based on the above-mentioned vehicle-bridge coupling vibration test system.Analysis of influencing factors of vehicle-bridge coupling vibration test.The influence rules of test factors such as lane location,vehicle-bridge mass ratio,bridge support form,bridge pier height,different test models and different bridge test models were discussed.The results show that: 1)Different lanes do not respond much to the axle dynamics.The driving lane can be selected according to the actual situation during the test.2)During the test,when the vehicle weight is 45.24 kg,the axle dynamic response is large.3)When the test vehicle runs on the bridge test section with different support forms,the measured dynamic response of the bridge is more obvious.Among them,when the vehicle is driving on the bridge in the form of support 2,the vibration response of the axle is more obvious,and the time-history curve is smoother.4)The pier height is in the range of 0 ? 500 mm,and the pier height has little effect on the amplitude of the vehicle-bridge coupling dynamic response.5)In order to obtain a more significant axle dynamic response during the test,a vehicle model with a smaller wheelbase can be selected.6)When the vehicle runs on different bridge types,the mid-span vertical displacement,acceleration and vehicle body vertical acceleration amplitude of the beam-slab bridge are the largest.The vehicle-bridge coupling vibration effect of steel truss bridge and box girderbridge is not obvious.