Study On The Fatigue Damage Of Suspenders Of Tied Arch Bridge Under The Load Of High-speed Train

Since the end of the 20 th century,railway has once again emerged in an all-round way in the world.One of the most important signs is the development of high-speed railway,especially in the past decade,China's high-speed railway has made remarkable achievements.Because of its light weight,large span capacity and beautiful appearance,tied arch bridge is favored by bridge builders and widely used in high-speed railway at home and abroad.The suspender is the main force transfer member which transfers the dead load and live load of the bridge deck to the arch rib.When the high-speed train passes through the bridge,the bridge may produce a large vibration,which will lead to a large range of stress changes in the suspender.Combined with a high-speed railway steel box tie arch bridge as the engineering background,this makes the following study on the fatigue damage of the suspender under the vibration load of high-speed train in operation:(1)Explain the influencing factors of high-speed train vibration and determine the high-speed train vibration load model.Based on the induction and analysis of the basic theory of fatigue,the fatigue analysis method of railway bridge and the cumulative calculation method of linear fatigue damage,the basic methods of fatigue damage research on the mast of high-speed railway tied arch bridge are summarized.(2)Using ANSYS software to establish the finite element analysis model of the steel box tied arch bridge,and carry out modal analysis to verify the accuracy of the finite element model.(3)Analyze the internal force change of the suspender under the action of static load and dynamic load,select four unfavorable suspension rods as the typical research object of fatigue,andThen the stress history of different parts of the suspender is calculated by using ANSYS transient analysis methodr.Analysis of the stress history curve of different parts of the suspender,to determine the joint where the suspender and the tie beam are the most vulnerable to fatigue damage.(4)Study the influence of train vibration load on the stress history and stress amplitude of the suspender,and obtain the stress amplitude spectrum by rain flow counting method,then use Miner linear cumulative damage theory to calculate the fatigue damage and design reference period of the suspender after train passing.The results show that the suspender will not suffer fatigue failure during the design reference period under repeated train loads.(5)When the train passes the bridge at different speeds,different driving positions and different marshalling lengths,the equivalent stress amplitude and fatigue damage degree of the suspender are calculated,and the influence of different operating conditions on the fatigue of the suspender is discussed.