Research For Fatigue Life Of Concrete Girder Bridges Considering The Degradation Of Long-term Performance

In China,more than 90% highway bridges are small and medium span concrete beam bridge.During the service period of the bridge, the long-term performance of bridge is degraded because of the influence of the external loads and environmental factor,especially due to the growth of traffic and overload vehicle,the bridge appear of obvious fatigue damage.Even the bridge collapses due to the serious overload.This article embarks from the basic fatigue life analysis model of concrete girder bridge,calculating the fatigue life of concrete girder bridge considering the factor of long-term performance degradation or not.Futhermore,we can put forward the suggestions for the fatigue performance evaluation method of concrete girder bridge,specific content as follows:(l)The fatigue life model of concrete bridgeAccording to the previous study or design code about the fatigue life calculation of concrete girder bridges at home and abroad,we can get a suitable fatigue life analysis model which is appropriate for calculating the fatigue life of concrete girder bridge with comparison and analysis. Based on the testing traffic data,this paper formulate a fatigue load model which is suitable for the analysis and calculation.(2)Analysis of the fatigue life of concrete girder bridges considering the degradation of long-term performanceFrom the testing data about long-term performance of concrete girder bridge which is extracted from Guangdong, Chongqing, Liaoning, Zhejiang province,this paper makes a statistics about the typical disease of concrete girder bridge.Based on the statistics,we can conclude a time-varying curve of long-term performance degradation for the concrete girder bridge. According to the results we can discusse the influence for concrete bridge's fatigue life considering the factors of degradation of long-term performance.(3)The fatigue performance evaluation of concrete girder bridgeThis paper put forward a fatigue performance evaluation index system by the fatigue life analysis model and the results of calculation which is applicable to assess the fatigue performance of concrete girder bridge.It makes it easier to evaluate the fatigue resistance of concrete girder bridge based on the related design parameters and testing data on spot.