Evaluation And Damage Identification Method Of Girder Bridge Based On Flexibility Matrix

Bridge is the key engineering in transportation. In order to guarantee smooth traffic and reduce the loss, the technical condition of the bridge need to be recognized in time. Static load test was generally used to assess the bridge technique condition and calculate the load-bearing capacity of bridge. However, static load test costs lots of money and time, and the normal operation of the bridge was impacted. While dynamic test method could detect structural damage quickly, and save the test funds. Dynamic test method is much valuable for research and apply.The current bridge load-bearing capacity is calculated by combining bridge displacement under static load test and the existing bridge load-bearing capacity evaluation procedures. In this paper, combining the bridge modal displacement under loads calculated by the flexibility matrix method with the existing bridge load-bearing capacity evaluation procedures, the bridge load-bearing capacity and damage location could be recognized quickly. Firstly, the modal flexibility matrix method and mode shape normalization based on the mass-change method were introduced in this paper, and the influence factors by finite element method were analyzed. Secondly, the damage factor calculation method based on sensitivity of flexibility matrix was deduced, and the influence factors by finite element method were analyzed. Finally, based on the theory and method above, the beam dynamic test and the damage simulation test data were analyzed to verify the feasibility of the method in practical application.The finite element calculation results and the test results of the test beam show that the bridge modal displacement under loads could be calculated accurately by combining the modal flexibility matrix method and mode shape normalization based on the mass-change method. And the bridge load-bearing capacity could be evaluated by combining the modal displacement and the existing bridge load-bearing capacity evaluation procedures. With the damage factor calculated by the flexibility matrix sensitivity method and the generalized flexibility matrix sensitivity method, the damage location in the bridge could be better identified.