Studies On Structural Identification Method In Civil Engineering

In order to overcome the identification difficulties caused by measurement incompleteness and data error, this dissertation is devoted to study the methods and application of structural identification in civil engineering using the static displacement, the modal data and the response in the time domain.Based on the extensive investigation of the literature, research situation of structural identification in civil engineering was summarized. The incomplete and noisy measurement was realized the main adverse factor to hamper the development of structural identification. Study on the identification method with the incomplete and noisy measurement was the research direction in the future. The significance of this dissertation was expounded and the research scheme was determined.Aiming at the structural identification problem based on the static displacement extensively existing in civil engineering, the partial eigenstructure assigned method was presented to identify the structural parameters. Then the parameter group and identifmbility criterions were discussed. The identification algorithm based on the Simulated Annealing-Simplex Shape algorithm was proposed. Several numerical examples of structural parameter estimation, structural damage identification, dam parameter inversion and geotechnical engineering were demonstrated that the proposed method had the good numerical steadiness and robustness to resist the data error with the condition of the incomplete and noisy measurement.In order to avoid the possible error of damage location by the flexibility comparison method, the flexibility projection method to locate the damage was proposed. Firstly, the sensitive property to the low modes and the location principle of the flexibility projection method was theoretical proved. Secondly, based on the comparative study on the model reduction and the mode shape expansion, the flexibility projection method was combined with the multi-objective optimum mode shape expansion algorithm to achieve the damage location with the limited measurement. Finally, the weighed flexibility error was defined on the frame of the statistical meaning to solve the damage location problem with the condition of data error. The numerical simulations were carried on the typical structures, and the results show that the flexibility projection method can effectively locate the damage with the incomplete and noisy measurement.On the basis of the flexibility projection method, the method of damage identification using the measured flexibility was proposed. Based the measured flexibility, the identification model of the partial eigenstructure assignment was presented. The linear algorithm, the pseudolinear algorithm and the fully nonlinear algorithm were established, and the comparative studies were carried on the above algorithms. The fully nonlinear algorithm was determined to solve the identification problem based on the measured flexibility. By using of the frequency, which is more accurate than the mode shape, the fully nonlinear identification algorithm using the frequency data was coupled with the flexibility projection method to estimate the magnitude of damage in a structure.At present, structural identification in time domain excited by ground motion is an importantresearch topic in civil engineering. A two-stage method, which can estimate structural parameters down to the element level based on incomplete response data alone without measuring the input excitations, was proposed. The method consists of two stages: sub-structural inversion of ground motion using least-square estimation, and parameter identification using extended Kalman Filter. Firstly, the inversion of the ground motion with the unknown parameters and limited measurements was studied by the sub-structural identification, and the least-square algorithm of unknown input was built. Secondly, based on the estimated input, structural parameter down to the element level was identified in time domain by extended Kalman filter algorithm. Several cases of a 6-sto...