Study Of Theory And Applied Method For Structural Damage Detection Based On Wavelet Transform

The complex structure will damage during their lifetime with the effect of design loads and other unknown loads, and the damage is harmful for structures security. So the detection and identification of structural damage, and servicing technique and measure based on it are vital to ensure structure security, lessen loss and prolong structural lifetime during the structural working and using period.In this thesis, the theory and its application for structural damage detection based on wavelet transform are studied carefully. The main efforts are devoted to the following aspects:At first the definition of structural damage and the classification system for damage identification method are given in the thesis. The structural damage is defined as the changes of structural performance, intentional or unintentional, which affects the current or future performance of the system. The damage detection are divided into four levels from simplicity to complexity, currently the study of structural damage detection mostly focus on the level of damage identification.Secondly the structural damage detection methods based on signal dealing are studied, wavelet analysis method is studied especially. The characteristics of Fourier translation, windows Fourier translation and wavelet translation are compared, the theory and the characteristics of wavelet analysis are studied carefully, and some common wavelets are introduced.Lastly the application techniques of wavelet analysis for the detection of structural damage are studied in this thesis, such as signal singularity identification, signal elimination noise. And according to the principle of structural dynamic time history method, the structural analysis program is designed, which make use of MATLAB language. The application of wavelet analysis theory in structural damage identification is studied.The result of study show that wavelet analysis method that it is used to detect the structural damage online is excellent, the method conquer the defect of traditional method that they can not time the damage and local the site of damage in structure simultaneously, namely the method can detect andidentify structural damage promptly while it happens, consequently structural damage is detected and identified early, and the authentic foundation is provided for the service and reinforcement of structure.