Residue Fatigue Life Evaluation And Fatigue Reliability Analysis Of Existing Steel Highway Bridge

Recently ,a lot of steel highway bridges which were built in last 50's or 60 's are entering into their aged stages. These bridges were desighed according to a lower load level criterion and because of the rapidly increasing heavy traffic and overload vehicles these steel highway bridges are under severe local damages. So there are many concealed safety defects in these steel bridges. How to appropriately evaluate the state of these steel bridges and analyze their residue fatigue life has become an urgent problem. In view of the existing situation, in association with the scientific research projection of the evaluation and reinforcement of Wubu Yellow River Steel Highway Bridge of Shaan'xi province, the paper inquires into the method of how to evaluate the residue fatigue life of the existing steel highway bridges and how to analyze their fatigue damage according to the structural reliability theory. The specific content is as listed below.The paper introduces the basic concepts and methods used in the analysis of fatigue damage. It also introduces the method and procedure of the evaluation of residue fatigue life according to the theory of nominal stress method.In association with the case of the evaluation of the residue fatigue life of Wubu Yellow River Steel Highway Bridge, the paper discusses the method of the evaluation of the residue fatigue life of steel bridges which is practically used. The method of set up bridge's traffic stress spectrum based on the present traffic is introduced. The practically used method of how to evaluate the accumulated fatigue damage and residue fatigue life is introduced.Some noticeable problems in the test of the fatigue nature of the existing steel are discussed. The result of the test is analyzed. A method is presented which is used to evaluate the residue fatigue life of the existing steel highway bridge based on the fatigue test of the used steel. Then the residue fatigue life of the lower string H-beam of the Wubu Yellow River Steel Highway Bridge is evaluated based on the method introduced above.Combining the structure reliability theory with the fatigue analysis method, the paper introduced the method of calculating the fatigue reliability of structure according to fatigue damage cumulative model. The fatigue damage analysis method which is based on fatigue life model is briefly introduced.Through the evaluation of the residue fatigue life of Wubu Yellow River Steel Highway Bridge the paper gives a basis for the afterwards naintenance of the bridge and for the Shaan'xi province's road programming. The method introduced in the paper is universallyuseful; and it may used to evaluate similar bridges.