Damage Identification And Alignment Adjustment And Control Method Of High-speed Railway Arch Bridge Based On Substructure Model Updating

In recent years,with the expansion of railway construction and the acceleration of the construction speed in the western mountainous areas in China,a number of large-span railway arch bridges have been or are about to be put into operation in complicated difficult mountainous areas.The harsh environment and the deformation of the long-span bridge itself may have adverse effects on the safety of the bridge structure and the running performance of vehicle.With a view of high requirements for track smoothness of high-speed railway long-span arch bridge,on the basis of substructure finite element model updating,the thesis conducted the research on structural damage and bridge deck alignment adjustment and control method for the high-speed railway arch bridges.(1)Based on the substructure method,a fast method for solving the eigenvalues and the eigen-sensitivities of large high-speed railway bridge were proposed.In this method,the eigenvalues of the whole structure were calculated by a small number of main modes of substructures,and the contribution of ignored modes was compensated by residual flexibility matrix.The effects of different main mode orders of substructure and different substructure division methods were studied on the eigenvalues and eigen-sensitivities.Compared with the method of solving eigenvalues and eigen-sensitivities of the whole structure,the accuracy and the efficiency of the proposed substructure method the method was verified to calculate the eigenvalues and eigen-sensitivities.(2)The finite element model updating algorithm based on substructure method was proposed.Taking the steel truss arch bridge as the background,the frequency differences and computing efficiency before and after the finite element model updating were compared using global and substructure method.And the finite element method was used to identify the structural damage of the bridge,in which the noise robustness of the proposed method was verified by the identification of the different damage locations,damage degrees and noise levels.(3)Introduing Chebyshev polynomial approximation and the finite element shape function,the moving load was equivalent to the force at the node of the beam element.The polynomial orthogonal coefficient and element damage parameters were used as the correction parameters in the simultaneous identification process.By deriving the sensitivity equation of dynamic response with respect to the orthogonal coefficients of moving load polynomials and element damage parameters,the explicit expression of structural dynamic response sensitivity matrix was obtained.The objective function of regularization was established by using the sensitivity matrix,and the regularization parameters were determined by of L-curve method.And the orthogonal coefficient of moving load and element damage parameters were optimized by Tikhonov regularization method.Through the dynamic response analysis of high-speed railway steel truss arch bridge under the action of moving load,the unknown moving load and the structural damage location were identified accurately and effectively.Meanwhile,the effects of vehicle speed and location damage were discussed on the accuracy of simultaneous identification.(4)For high-speed railway steel truss arch bridge and concrete arch bridge,the vehicle-bridge coupling analysis model was established.The dynamic responses of vehicle and bridge were obtained for the different damage cases,including different structural parts of arch bridge(only the girder,the combination of girder,pier on arch and arch rib)and different supports(single support and two adjacent supports).(5)Based on the chord measurement method and empirical mode decomposition method,the correlation between the vehicle vibration characteristics on the track and the chord values under the excitation of two track irregularities was studied via the correlation coefficient index.For the problems of the two static deck deformations of long-span bridges caused by temperature,shrinkage and creep,two long-span high-speed railway concrete arch bridges were taken as the background.The dynamic responses of the vehicle and bridge were analyzed,and the critical shrinkage and creep deformation curves for different track irregularities are obtained.Then,the effects of reference chord length on the correlation between train vibration characteristics on the bridge and chord values of arch bridge were discussed.Furthermore,the limit value of high-speed railway concrete arch bridge deck deformation was put forward.Finally,from the perspective of structural safety,the stress of track and girder in the height adjustment process was analyzed,and the deck adjustment scheme was put forward.