Analysis Of Vehicle-bridge Coupling Vibration Response Of Heavy-duty Vehicles To Continuous Beam Bridges

With economic development and rapid development of highways in my country,small and medium-span bridges are widely used in highways.The vehicle load effect of small and medium-span bridges is generally determined by heavy vehicles,and a large number of heavy and overloaded vehicles directly threaten the safe operation of the bridge.In this paper,three continuous beam bridges with the same span and different cross-sections and five small and medium-span continuous beam bridges with the same cross-section and different spans are used as the research objects to establish a vehicle-bridge coupled vibration model of the continuous beam bridge.Analyze the impact of heavy vehicle load on the impact effect of small and medium span continuous beam bridges.The main work and conclusions of this paper are as follows:(1)On the basis of ANSYS software,three finite element models of small and medium span continuous beam bridges with three different sections and five with the same cross-section and different spans were established.Analyze the dynamic characteristics of eight small and medium-span continuous beam bridges.The results are as follows: In the dynamic characteristics of single-box double box girder bridge,the torsional mode only appears in the5 th order frequency,which is different from the other two forms of section.Assembled T-shaped continuous beam bridges with the same cross-section,changing the span and beam height,the first-order mode characteristics of the continuous beam bridge are the same,and the first 10 modes have similar characteristics,but the frequency is different.(2)According to the D’Alembert principle and vehicle vibration characteristics,considering the vertical and lateral vibration of the vehicle body,rollover and pitching vibration,the fiveaxis vehicle is simplified into a three-dimensional 15-degree-of-freedom mass-spring-damping system.The vibration equations of the vehicle-bridge coupling model of the five-axle heavyduty vehicle with 15 degrees of freedom are deduced and solved by MATLAB.(3)Three 3×20m continuous girder Bridges with different cross sections are taken as objects,the effect of heavy-duty vehicles on the vehicle-bridge coupled vibration response of a small and medium-span continuous girder bridge is studied.Analyze the effects of vehicle loading position,driving speed,vehicle weight,vehicle type,bridge deck flatness and damping ratio on the coupled vibration response of continuous beam bridges with different cross-sections.The results show that: the loading position of the vehicle has the greatest influence on the transverse direction of the continuous beam bridge of the T-beam section,and the least influence on the section of the single-box double-chamber box girder;When the vehicle is running at high speed,the mid-span deflection and fulcrum bending moment IM of the single-box doublechamber box girder bridge is the largest;The IM of the three types of continuous beam bridges all decrease with the increase of vehicle weight;The IM of bending moment of single box and single chamber box girder decreases the most,and the bending moment of single box and double chamber box girder decreases the least.When designing continuous girder bridges,it is recommended to consider the impact coefficient of the integral or separate main girder section,and consider the impact coefficient of the fulcrum bending moment.(4)Taking five continuous beam bridges with different spans as the research object,the influence of heavy-duty vehicles on the vibration response of continuous beam bridges with different spans is studied.Analyze the effects of vehicle loading position,vehicle speed,vehicle weight,vehicle type,bridge deck flatness and damping ratio on the vibration response of continuous beam bridges with different spans.The results show that the displacement and bending moment IM of continuous beam bridges with different spans keep decreasing as the span increases;The IM of mid-span displacement caused by a three-axle vehicle is generally smaller than that of a five-axle vehicle,and the fulcrum bending moment IM of a three-axle vehicle is generally greater than that of a five-axle vehicle.