Fatigue Damage Analysis Of Composite Girder Bridges Under Coupled Vibration Of Vehicles And Bridges

When the vehicle travels through the bridge,the bridge structure will be affected by the dynamic impact of the vehicle,which will have a direct effect on the bridge and thus affect its working performance and operation life.In addition,when the bridge structure is subjected to the impact force,it will produce obvious vibration effect,which will in turn affect the safety and comfort of the vehicle,and this circulation will form the multi-dof vehicle-bridge coupled vibration system.In the past,most of the researches on the fatigue performance of Bridges only consider the impact of vehicle load,but not the interaction between the wheels and the deck.But in fact,the bridge during service operation has many uncertain factors,under the condition of complex external factors of vehicle driving is bound to trigger a more unfavorable load and vibration,these can eventually lead to fatigue damage components,so the reasonable consideration of vehicle and bridge deck degradation factors is the key point of vehicle.the research.The dynamic response of the bridge is analyzed one by one by using the control variable method to analyze the factors such as the unevenness of the bridge,the speed of the bridge and the load of the vehicle.In order to accurately and effectively analyze the fatigue performance of composite girder Bridges,vehicle-bridge coupling must be taken into account,including the influence of multiple parameters such as change of speed,change of vehicle load,degradation of road surface,etc.,and a new fatigue calculation and analysis model of composite girder Bridges is established based on MATLAB mathematical programming technology.In this paper,the fatigue performance of composite girder Bridges is analyzed on the premise of considering the coupling effect of vehicle-bridge.The main research contents are as follows:1.Compile relevant calculation procedures.The second order differential equation was formulated based on MATLAB,the coupled vehicle and bridge vibration analysis program(to obtain the stress duration)and the rain flow program(to obtain the stress spectrum).2.Establish vehicle-bridge coupled vibration analysis model,bridge surface roughness model and random traffic flow load model;Based on the model,the dynamic performance of the bridge structure is analyzed,and the impact coefficient is discussed in terms of the change of vehicle speed and deck flatness.3.The fatigue stress spectrum was obtained through data processing by the rain flow counting method,and the fatigue damage of steel girder was calculated using the linear fatigue cumulative damage theory,and the fatigue life of components was then calculated.4.Established the fatigue analysis of shear nail components based on ANSYS,and obtained the shear nail fatigue effect analysis and the fatigue life evaluation of key fatigue components by taking into account the influence of factors such as the unevenness of the bridge,the speed and the coupling effect of the vehicle bridge.