Dynamic Response Analysis Of Long-span Suspension Bridge And Vehicles Under The Combined Action Of Random Traffic Flow And Cross Wind

The vehicle load is one of the most important components of bridge live load in highway traffic,and because it is complex and full of randomness,the search for a random traffic simulation method that can highlight the above characteristics and meet the loading accuracy has been a hot topic of research.In addition,due to long-span cross-river and cross-sea bridges are characterized by high wind velocity,and lack of bridge deck obstructions,the safety and comfort problems of driving in crosswind environment also requires focused attention.Therefore,it is of vital practical engineering importance to simulate the traffic loads more realistically,to study the dynamic response of the bridge structure under the action of random traffic and wind loads,and to evaluate the driving safety and comfort on bridge.This paper combines the cellular automata(CA)traffic flow theory with the wind-vehicle-bridge coupling theory to establish a wind-traffic flow-bridge analysis system.The main research and work are as follows:(1)Based on the basic theory of CA,the limitations of the classical N-S model are optimized by improving the accuracy of the unit cell,adding the lane change parameters,and interpolating the results.The composition of the traffic flow is determined based on the measured traffic flow information,and a more improved CA microscopic traffic flow model(ICA)was established.A random traffic flow simulation program that can output information such as the position and speed of any vehicle at any moment is written by MATLAB,the accuracy and superiority of the ICA model are verified through examples.(2)The dynamic equations of the bridge and vehicle subsystems were established respectively,and the three-dimensional finite element model of the bridge was established by the finite element software MIDAS.Based on the idea of the whole process iterative method,the vibration response of bridge and vehicles are solved by the vibration superposition method and Newmark-βtime integration method.The pavement roughness is constructed by the trigonometric series method,and the pulsating wind field is constructed based on the fast spectrum analysis method.The wind coefficients of the stiffened beam and vehicles are obtained by wind tunnel test and numerical simulations.The driving safety are evaluated by the roll safety factor RSF and the sideslip safety factor SSF,and the driving comfort is evaluated by the overall weighted RMS acceleration a_w.A coupled wind-vehicle-bridge analysis program was developed by MATLAB to generate random traffic flow and to evaluate vehicle traffic indices.(3)Taking a long-span highway suspension bridge as the engineering background,through the compiled program to calculate vibration responses of the main beam and vehicles under the independent action of random traffic load and the combined action of random traffic load and wind load respectively.The influence of heavy vehicles ratio,number of vehicles,driving speed,road surface roughness,and wind speed on the critical location of the main beam were investigated.This paper to study the driving safety and comfort of the random traffic flow generated by CA in the wind-vehicle-bridge system.The effects of the proportion of heavy vehicles,number of vehicles,driving speed,road surface roughness,wind speed,vehicle load,and road conditions on vehicle vibration were investigated.