The Fatigue Assessment Of Hanger Wires Of Suspension Bridges Based On Measured Traffic Flow Data

With the rapid economic development in our country,the transport industry in our country has made tremendous achievements.Many long-span bridges spanning the river,across the sea and across the gorge have been built.Among them,the suspension bridge has the strongest span capability among all the bridge types.During the operation period of the suspension bridge,the long-term sustained effect of the car load makes the sling prone to fatigue damage,which in turn triggers catastrophic events and causes heavy losses to the society.Based on the existing research and combining with the example of Nanxi Yangtze River Bridge,this paper has done the following work for the sling of Nanxi Yangtze River Bridge:(1)A lot of relevant Chinese and foreign literatures have been carefully studied and read in the previous period,on the basis of which,the related theory of fatigue and the status quo of sling fatigue research are summarized.Relevant factors that affect the fatigue performance of suspension slings are described.The calculation theory of suspension bridges and the development of two kinds of sling fatigue life assessment theories are introduced.(2)The related concepts of shadow plane and the current research status are introduced.The finite element model of Nanxi Changjiang River Bridge is established by ANSYS software.The influence surface data of the bridge is obtained by finite element numerical simulation.The software fits the data of influence surface calculation.(3)The traffic flow data such as lane,arrival time,vehicle speed and vehicle weight collected by WIM dynamic weighing system were analyzed and processed.The influence surface load program of sling stress history was compiled by Matlab software.Based on this,The law calculated the sling stress amplitude and stress cycles.(4)The fatigue strength curve of slings and the theory of cumulative fatigue damage are introduced.The fatigue damage of slings in 2014 is calculated by MATLAB software based on the principle of Miner linear cumulative damage.Considering the traffic growth of Nanxi Yangtze River Bridge,The fatigue life of the slings in Nanxi Changjiang River Bridge under the condition of increasing traffic flow shows the fatigue life of the slings.Compared with the fatigue damage of the slings which does not consider the increase of the traffic flow,the fatigue life of the slings considering the increase of traffic flow is significant Reduce;finally according to the fatigue damage of sling divided into grades,developed sling inspection measures.