Study Of Modeling Method For Vehicle-Pavement-Bridge Interactional Vibration System

With the rapid development of the economy,the number of vehicles and the vehicle load is increasing.Meanwhile,Bridges tend to be more lightweight so that bridges vibrate more obviously induced by vehicles.This makes the problem of vehicle-bridge interaction attract more and more attention.As an important part of a bridge,the pavement has light-weight and small stiffness.It is the most prone to deteriorate.And the deterioration can aggravate the vibration of vehicle and bridge.Due to the interactive relationship among vehicle,pavement and bridge,a complex vehicle-pavement-bridge interaction(VPBI)system is formed.However,the pavement is almost not considered in current models of vehicle-bridge interaction system.In this thesis,modeling methods utilizing the semi-analytical method and finite element method for the VPBI system are proposed and vibration responses of the system are studied.The main contents of this thesis are as follows:(1)A two-dimensional vehicle-pavement-bridge interaction(2D-VPBI)system is established by semi-analytical method.The vehicle is modeled as a quarter car model,of which tires are in contact with pavement by a contact surface.The bridge is modeled as a simply supported Euler-Bernoulli beam.The pavement is simulated with the continuously and uniformly distributed spring-damper,of which equivalent stiffness coefficient and equivalent damping coefficien considering viscoelastic properties of pavement are calculated.The equations of motion for 2D-VPBI system are derived by using the Lagrange equation and D’Alembert principle and can be solved by Newmark-β method.The effects of vehicle velocity,bridge span,tire-pavement contact area,equivalent stiffness coefficient of pavement,and equivalent damping coefficient of pavement on dynamic responses of 2D-VPBI system are analyzed.The results indicate that the pavement deformation fluctuates around the initially static deformation of pavement.The maximum response of 2D-VPBI system increases exponentially with the increment of bridge span.(2)A three-dimensional vehicle-pavement-bridge interaction(3D-VPBI)system is established by the finite element method.The vehicle is modeled as a full car model with seven degrees of freedom.The bridge is modeled as a three-dimensional solid finite element model of which material of pavement has viscoelastic properties.The coherence of road roughness for left tire and right tire is considered.The interaction between vehicle and pavement is established by the constraint equation method.Moreover,the correct of model is validated by comparing 3D-VPBI system with 2DVPBI system.Furthermore,the effects of road roughness coherence,road roughness grade,pavement thickness and vehicle velocity on dynamic responses are analyzed in time domain and frequency domain.The results indicate that if the road roughness is poor,the coherence of road roughness under the left and right tire needs to be considered in order to make calculated responses closer to reality.(3)Based on 3D-VPBI system,dynamic responses of the system under complex working conditions are studied.The complex working conditions include twin-vehicle load and deterioration of pavement.The effects of lateral and longitudinal distance of vehicle,mass of twin-vehicle and deterioration of pavement on dynamic responses are analyzed.To analyze the dynamic responses quantitatively,evaluation indices that are the weighted vibration levels,the impact factor and the number of equivalent stress amplitude are used.The results indicate that controlling the longitudinal distance of vehicle and the sequence of light and heavy vehicles can effectively reduce the dynamic response of the vehicle-road-bridge interaction system subjected by the twin-vehicle load.The deterioration of the road roughness will aggravate the vibration of vehicles,bridges and pavement.The research results of this thesis can provide more accurate and reliable vibration response for parameter identification,damage identification and load identification of the vehicle-pavement-bridge interaction system.