Study On Damage Identification Method For Railway Bridge Rubber Bearings Based On Dynamic Responses

State-of-arts and problems of bridge rubber bearing damage detection are pointed out. The advantages and limitations of traditional model updating damage identification method with modal parameters as input are elaborated. On this basis, a dynamic detection method based on Fourier transform assuerance cretrion (FAC) and model updating theory is proposed for rubber bearing damage evaluation. A railway T-shaped girder and a multi-span continuous box girder are used to test the proposed theory. Finally, in-situ experiments were conducted on one ShuoHuang railway bridge to verify the applicability and effectiveness of the proposed method. The main work and conclusions are as follows:(1) The concept of the Fourier assuerance cretrion (FAC) and the model updating theory are combined to propose a dynamic identification method for bridge bearing damage detection. Moreover, corresponding basic theory and calculation criterion are erected.(2) By analyzing a three-span continuous girder and a five-span continuous girder, the principles of frequency band selection and measurement point arrangement plan are studied, which is the basis for subsequent damage identification calculation.(3) The frequency band selection principle and measurement point optimal arrangement plan are further verified by a railway double T-shaped beam example. Thus, the proposed bearing damage detection method is extended to spatial structures.(4) Field tests was conducted on a railway bridge of Shuohuang Line and the stiffness of the bearings were identified. The identified bearing stiffness is used in the finite element model of the bridge to calculate the dynamic responses. The calculated dynamic responses agree well with the measured one, which proves the effectiveness and applicability of the proposed evalution method for railway rubber bearing damage.