Research On The Position And Quantitative Analysis Of Structural Damage Identification

Engineering structures serving in complicated environment often suffer different kinds of damages, accumulation of such damages easily results in catastrophes, so it is very important for safety of structures to detect the early damages of structures. The purpose of structural damage detection is to identify the location and the grade' of structural damages based on the characteristics represented by structures. The identification of location and grade of structural damages is involved in positioning techniques and quantitative analysis of structural damage detection. The positioning techniques and quantitative analysis of structural damages are thoroughly studied by introducing the modern mathematical methods. The main researching fields are as following:1 The current dynamics methods of structural damage detection are systematically analyzed, the advantages and disadvantages of the methods are compared. The reverse figuring ways of current structural damage detecting methods are classified and compared. The new method of damage detection is advanced, which is based on using the modern mathematics.2 The sensitive grades of structural displacement mode and strain mode for structural damages are respectively studied through experiments, which help to chose the indicator for positioning structural damage.3 the changes of strain mode before and after the occurrence of structural damages are viewed as random variables. The discrete model of structural damage position is established by introducing the method of test of even change point. The method can be used to quantitatively analyze the locations of different damages.4 The normal matrix in the normalized iterative method often used in structural damage detection is always empirically determined. The selection of normal matrix is theoretically discussed. The relation between the selection of normal matrix and converging domain and speed is analyzed, which establishes the theoretical fundament for selection of normal matrix.5 Because of the limitation of initial values in the chiastic iterative method used in structural damage detection, a new structural damage detecting method,homotopy continuation algorithm, is established, which is based on the modern nonlinear numerical analysis. The convergence of the method is independent of selection of initial values. The numerical examples prove the method is effective.6 The damages of a hanging cable bridge are positioned by using the method of the test of even change point. The simplized finite element model of the bridge is established. The finite element method is integrated into the homotopy algorithm. The initial values of the damage grade are obtained by homotopy continuation algorithm. The Newton iterative method is used to find the ultimate values of the damage grade of the bridge. The structural damages of the hanging cable bridge are positioned and quantitatively analyzed by using the combined methods.The computational software is developed, which is based on the test of even change point, homotopy continuation algorithm and the iterative method...