Analysis Of Abnormal Vibration Factors Of Bridges Based On Vehicle-Bridge Coupling

The design requirements of the bridge not only need to meet the corresponding bearing capacity under the static load test,but also under the dynamic load of the vehicle,the vibration deflection should be controlled within a reasonable range.Excessive vibration response not only causes damage to the bridge structure,but also poses a safety hazard to the service life of the bridge.It also causes psychological stress on people's driving comfort on the bridge.In response to this situation,the author has carried out the following research.Firstly,the author deduces and introduces the relevant basic theories of vehicle-bridge coupling,obtains the differential equation of the theoretical model,and solves the equation by numerical algorithm in MATLAB.At the same time,the author also established the finite element model of the classical model based on the displacement contact method in ANSYS software and calculated it.Then the author compares the results calculated by the two methods and finds that the degree of coincidence is high.After that,the author introduces the motion equations of two common vehicle models and the simulation implementation in ANSYS,and compares them with the calculations of related literatures to further verify the correctness of the simulation method.The author also uses the triangle series method and the fourier inverse transform method to simulate the road roughness respectively.The author compares the two simulation results and finds that the fourier inverse transform method has better simulation effect.Finally,the author established a finite element model for a specific continuous rigid frame bridge in ANSYS,and designed different combinations of vehicle speed,unevenness level and driving distance,and simulated the situation that may cause resonance.The author found that when the fundamental frequency of the vehicle is close to the main vibration frequency of the bridge,the resonance effect will cause the bridge vibration response to increase significantly.Under ideal smooth conditions,the impact of the vehicle on the bridge increases with the increase of the speed,but the impact is not obvious compared with other factors.Under the condition of uneven road surface,when the vehicle speed is changed so that the excitation frequency of the vehicle is close to its fundamental frequency,the vibration shock of the bridge is not obviously increased.At this time,the impact of the driving speed on the impact effect of the bridge is dominant,and the effect of the speed is obviously enlarged compared to the ideal smooth road surface condition.When the frequency of the vehicle's action on the bridge is close to the main vibration frequency of the bridge,the vibration response of the bridge will be intensified,but the effect is not obvious when the vehicle's fundamental frequency is close to it.The reduction of the constrained stiffness of the bridge will cause the main vibration frequency of the bridge to be alienated from the vehicle's fundamental frequency,and the deflection amplitude of the bridge will increase,but the impact coefficient will decrease.