High Rise And Long Span Continuous Rigid Frame Bridge In Mountain Canyon Driving Safety Research

With the continuous improvement of infrastructure construction,large-span continuous rigid frame bridges are built in mountain valleys,and these bridges are often in strong wind environments;the vibration response of vehicles and bridges under wind load will increase accordingly,and will also reduce the Comfort and driving safety;coupled with the frequent occurrence of bad weather such as rain,snow,and ice in recent years,the driving safety of vehicles has been further exacerbated,making the research on driving safety of vehicles on bridges more and more important.In this paper,the Murong Bridge in the mountain valley is used as the engineering background.Based on the windvehicle-bridge coupling vibration theory,the wind-vehicle-bridge coupling vibration analysis program is used to establish an analysis model to analyze and study the driving safety of the continuous rigid frame bridge.The main content of this article:(1)Determine the design reference wind speed of the bridge through the basic wind speed analysis method of the hypothetical virtual standard weather station.Through the actual wind speed observation data of the meteorological observation station within200 km around the bridge site area,considering the influence of altitude and terrain,the design reference wind speed of the Murong Bridge bridge site area is obtained after correction,and the bridge is generated by the self-editing program and the harmonic synthesis method Three-dimensional pulsating wind field in the site area.(2)Use finite element software to establish the finite element model of the continuous rigid frame bridge and perform modal analysis;establish the equations of motion of the two-axis vehicle and the three-axis vehicle based on the D’Alembert principle.(3)Based on the wind-vehicle-bridge coupling vibration theory,the triangle series method and the harmonic synthesis method are used to simulate road roughness,and the wind-vehicle-bridge coupling vibration differential equation is established considering the effect of wind load on the bridge and the vehicle.The Newmark-β method solves the vibration equation.(4)Based on the CFD numerical simulation theory,the Mavericks CFD twodimensional fluid calculation software is used to establish the vehicle-bridge crosssection model,and the fluid analysis is carried out to determine the static three-component force coefficient of the cross-section;for different cross-sections and different vehicles,the vehicle-bridge cross-section Analysis and research on the influence of static coefficient.Through the analysis,it is found that the change of the bridge section has a significant effect on the drag coefficient and the lift coefficient of the bridge,and has little effect on the torsional moment coefficient of the section.With the increase of the beam height,the resistance coefficient gradually increases,and the lift coefficient gradually decreases;As the wind angle of attack increases,the resistance coefficient of the bridge section presents a "V" trend that gradually decreases and then increases.The resistance coefficient of the bridge section fluctuates greatly,without obvious rules,and the torsional moment coefficient of the bridge section as a whole The trend is gradually decreasing;the vehicle has little influence on the drag coefficient of the bridge section,and the influence on the lift coefficient and torsional moment coefficient of the bridge section is relatively obvious;(5)Introduce road vehicle safety evaluation standards,and use wind-vehicle-bridge coupling vibration software to analyze and study the driving comfort and driving safety of random traffic under different road levels,different wind speeds,and different road friction conditions.Through analysis,it is found that as the roughness of the road increases,the angle of beam end angle and vertical displacement change little,and the vertical vibration response of the vehicle gradually increases;the vertical,lateral and torsional angular displacements of the bridge span are all proportional to the wind speed Non-linear increasing relationship;(6)when ignoring the effect of wind load,the vertical vibration response of Type A vehicles(three-axis fully loaded heavy goods)is the smallest,and the vertical vibration response of Type D vehicles(van empty load trucks)is the most intense.The quality,stiffness and The damping characteristics have a very obvious impact on the vehicle’s vibration response;the D-type car(van-type full-load truck)has the worst ride comfort,the C-type car(van-type empty-load truck)is next,and the A-type car(three-axis fullload weight)Cargo)and Type B(two-axle full-load heavy goods)comfort is relatively good,and Type E(car)has the best ride comfort;wind load has little effect on the vertical comfort of the vehicle,mainly affecting the lateral comfort of the vehicle As the wind speed increases,the lateral comfort of the vehicle gradually decreases;when the average wind speed is 15 m / s(the instantaneous wind speed is 15.168 m / s),the E-type car(sedan)will slip,when the average wind speed is 20 m / s(the instantaneous wind speed is21.061 m / s),the E-type car(sedan)will roll;the average wind speed is 10 m / s.When snow pavement appears on the road,the E-type car(sedan)will skid.After the road freezes,the D-type car(car)Cargo trucks)and E-type vehicles(sedans)will slip.