Research On Monitoring Capability And Technique Of Fatigue Sensor And Analysis Of The Monitoring Data On Donghai-bridge

Fatigue damage is one of the mostly factor of structure degradation of long-span bridges. As the accretion of the bridges'loading and the manifoldness of the bridges'fatigue rupture accident, the structural fatigue damage monitoring has been the head and front of long-span bridges'design and health monitoring. Though limitation, economic and low reliability exist in the traditional monitoring technology. The fatigue gage is a perfect sensor in monitoring fatigue estate when the structure is loading, its resistance value increases with the fatigue experience and increased resistance value is preserved when applied load is removed, so it is important gage in the fatigue damage monitoring of the long-span bridges. But there are still many problems when it is used on the fact project, such as the exorbitant threshold of fatigue life gage, the dispersible of resistance and so on.This paper is based on the country priority construction project--the health monitoring of Donghai-bridge. By research on the response of the fatigue sensor when it was used on Donghai-bridge, the main capability and technology of fatigue sensor on structural fatigue damage monitoring are obtained. The main points are as follows:Firstly, the performance of the fatigue sensor in experiment is tested. The multiply coefficients of the fatigue gages stuck on the strain multiplier are obtained by static tests. With the performance of the fatigue gages on the bending tests, the response of the fatigue sensor is studied by experimental and theoretical analysis when it is under loading of the combination of bending and polling. And the response calculation is obtained. Then the influence of temperature on the fatigue tensor is researched by the temperature tests and theoretical analysis. The fatigue test is carried to validate the method of calculating loading spectrum of bridges with two fatigue life gages which have different multiply coefficients but are stuck on the same strain multiplier. Secondly, based on the specialty of load spectrum of bridge, the response law of the fatigue gage under Reilay loading is obtained by the data of constant loading. Then the method to infer load spectrum of bridge with two fatigue gage stuck on the same strain multiplier is proposed. On the basis of Miner Law and the BS5400, the calculation of the bridge's damage is obtained. Considering the decentralization of the resistance, the errors of the fatigue damage is studied, and the best relations of the multiply coefficients of the two fatigue gages which are stuck on the same strain multiplier are obtained.Finally, all the data of the fatigue sensors on Donghai-bridge is well analyzed. By several idiographic monitoring data, the loading spectrum of the monitoring points is obtained and the damage of the points is calculated.