Dynamic Responses Of Beam Bridges Under Vehicular Loads

Transportation engineering is undergoing tremendous changes in today’s society.At the same time,people put forward higher and higher requirements for the transport structure.More and more attention has been paid to the damage judgment of the transport structure in the normal operation process and the daily maintenance of the transport line.In the traditional vehicle-bridge coupling research process,the upper vehicle load is simplified to the combination of mass block,spring and damping element.Point contact is usually used between wheel and road surface.This contact method is quite different from the actual contact between vehicle tire and road surface.In this paper,the finite element model of vehicle is modeled precisely,especially the contact between tire and road surface,so that the dynamic characteristics of vehicle loads running on bridges can be simulated more fully.Through this simulation,the factors affecting the working status of the bridge can be explored,so that the dynamic damage of the bridge can be reduced by changing the design structure of the bridge,and better economic benefits can be created.This paper establishes a complete vehicle model by HyperMesh software,and verifies the validity of the model by comparing theoretical calculation with finite element calculation.The establishment of vehicle finite element model mainly includes the simulation of suspension between tire and body and the contact between wheel and road.In order to ensure the accuracy of vehicle model,this paper does not simplify vehicle suspension and wheel,but simulates them as completely as possible according to the real suspension and wheel.In order to ensure the accuracy of vehicle-bridge contact simulation,in the process of finite element modeling of wheels,this paper simulates the inflatability of wheels by LS-DYNA keyword.There is gas pressure inside the tires,which can more accurately simulate the real contact between the wheels and the road surface.The bridge model adopted in this paper is a 30-meter simply supported beam model.The running status of vehicles on the simply supported beam bridge is simulated by ANSYS LS-DYNA software.The dynamic response of the bridge under different bridge positions,different vehicle speeds,road irregularities and other working conditions is solved.The influencing factors of vehicle-bridge coupling vibration are summarized.In order to improve the computational efficiency of vehicle-bridge coupling analysis,this paper also uses grillage method to model and analyze simple-supported girder bridges,and compares the results of grillage method with the results of solid modeling to verify the feasibility of grillage method to solve vehicle-bridge coupling vibration.This paper also verifies the influence of bridge damage on vehicle-bridge coupling vibration,and explores the changes of bridge displacement,vibration speed and vibration acceleration under different damage degrees,which provides a basis for judging the damage location and degree of bridge damage.At the end of this paper,ANSYS implicit solution method is used to study the vehicle-bridge coupling jumping phenomenon.