| As important components supporting the superstructures, piers are directly related to the safety of the whole bridge to some extent. A quick and convenient way to grasp the working states of existing piers is need, which is helpful to the reinforcement, maintenance and management of railway bridges. On the basis of the existing dynamic damage identification researches, the condition assessment method for railway piers based on dynamic parameters is studied. The main research work and results are as follows:(1)Damage identification method based on modal parameters and model updating theory is studied. Besides the modal frequencies and modal assurance criterion (MAC) of mode shapes, the ratio between the adjacent components of the first mode shape is introduced to construct the objective function. The numerical analysis shows that restriction function constructed by the first two order modal parameters is enough to identify both the structural damage of pier body and foundation deterioration. However, this method is highly sensitive to noise and test errors of mode shapes.(2) Signature Assurance Criterion (SAC) based on frequency response function (FRF) of adjacent points on piers is first used to form new objective functions. Combined with the model updating method, a damage identification method for railway piers based on SAC is proposed. By theoretical and numerical analysis, the application conditions, such as frequency band selection, measurement point arrangement and anti-noise ability of the method is studied. The analysis results prove that the proposed damage detection method is effective and reliable.(3)To further validate the SAC-based damage identification method, a1:3scaled model pier was tested and three different damage cases were simulated. The detected damage agrees well with the designed ones, which validates the effectiveness and feasibility of the proposed damage identification method for railway piers from the point of engineering application. |
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