Research On The Application Method Of Fatigue Sensor And Bridge Damage Analysis

Long-span bridge structures service under long-term alternate loads, strength degradation ofstructure materials because of fatigue cumulative damage is key factor of durability. In recent years,bridge health monitoring are attracted attention more and more. the digital fatigue is a sensorresponsed in resistance, the core component fatigue gage is made of copper-nickel alloys for specialannealing treating, which have a property of permanent resistance change when it experienced toaltered fatigue loadings, and the change can reflect the fatigue process of the structure, so it is aperfect sensor in monitoring the fatigue state of structure. this paper has done an in-depth study of themonitoring application from both theoretical and experimental verification.Firstly, bridge load spectrum calculation theory based on fatigue gage is proposed, including adescription of its basic features and principles, as well as account for resistance response to thevariable amplitude loading, etc. Based on the speciality of load spectrum of bridge, a new method toinfer load spectrum of bridge and Time-load spectrum with two fatigue gage was proposed, andprogram to implementation.Secondly, dynamic load tests were designed to verify the feasibility and accuracy of thecalculation model. By comparing the model calculation loads spectrum and real-time random loads toverify its feasibility. then Comparison of model calculations loads spectrum obtained with the knownloads spectrum to verify its accuracy. Analyze the statistical characteristics of resistance influence onthe results and error handlingAt last, an instance of damage calculation and lifetime evaluation to the East China Sea BridgeProject Monitoring was presented, accord to the bridge design code of BS5400 and Miner damagetheory, so as to show the steps of application and analysis of bridge fatigue damage assessment withfatigue gage.