Comparison And Analysis Of Reliability Evaluation Methods For Bearing Capacity Of Prestressed Concrete Box Girder Bridges

The extensive use of prestressed concrete box-girder bridge on the highway bridge made accurate assessment of the actual carrying capacity become more and more important. Because of the difference on bridges carrying capacity evaluation measure between China and America, comparative analysis of the two evaluation methods became a problem which was worth discussion.This dissertation analyzed the probabilistic finite element method in detail on the basis of introducing the theory and calculation method of reliability in bridge structure. The highway bridge load and resistance stochastic models were established, and the limit state equation of prestressed concrete box-girder bridges was derived. The difference between Chinese and American assessment method in bridge carrying capacity were compared and analyzed.Taked a variable cross-section prestressed concrete box-girder bridge for instance, this dissertation established three-dimensional solid finite element model of the upper structure by ANSYS software and simulating calculation on the cross section of main span was given. Loading test was applied in this bridge, then load test value and model simulation results were contrasted. The reasonableness of the established finite element model of the bridge was verified. The failure probability of flexural capacity and reliability index of this bridge were calculated by ANSYS PDS response surface method.Single box uniform section prestressed concrete girder bridge and composite box-girder bridge models were established. The failure probability of flexural capacity and reliability index of them were calculated, and sensitivity of parameter was analyzed. In conclusion, the reliability index in America was less than in China by comparing reliability of three different sections box-girder bridges. Lastly, the differences between the two methods were analyzed in various aspects by analyzing the variable parameters sensitivity of box-girder bridges. It can infer that the reliability index of our country’s evaluation method was influenced by the subjective factors mostly and the American evaluation system was stricter.