Time-Frequency Domain Damage Diagnosis Research Of Post-Earthquake Bridge Structure

China is an earthquake-prone country. Bridge structure plays a vital role in post-earthquake rescuing of lives and properties, bridge structure performance of post-earthquake is one of the topic focuses for government, engineer, etc. Damage diagnosis research of post-earthquake bridge structure is got more and more concern. Seismic excitation is nonlinear and n on-stationary random excitation and takes along with enormous energy. This make the damage diagnosis research of post-earthquake bridge structure is different from other damage diagnosis research. There are many limitations to use other damage diagnosis methods to post-earthquake bridge structure directly. Therefore, the research combined with the signal analysis theory of Hilbert-Huang Transform and the statistical learning theory of Support Vector Machine is specially for the damage diagnosis of post-earthquake bridge structure. The research completed the work of the following aspects:1. According to the characteristics of damage warning, the intact and damage state of the bridge is completely different, Time Energy Transfer Function and Hilbert Marginal Spectrum Transfer Function are the time-frequency domain damage index constructed to suit for damage warning of post-earthquake bridge structure. The damage location of bridge structure is non-accuracy, non-continuity and diversity. After the complex bridge structure will be divided into several intervals according to the nature of the adjacent and similar structure, the layered method dividing the damage location diagnosis into several levels is established to suit for the damage location identification of post-earthquake bridge structure.2. The method of damage warning and damage location diagnosis is verified through the example of pre-stressed concrete simple beam. The research shows the damage indexes of both damage warning and damage location diagnosis have the good ability both to distinguish and resist noise.3. After defining the easily damaged components of the damage diagnosis research of Lu Zhou Taian Yangtze River Bridge as the object of study, the index of damage diagnosis is used to long span cable-stayed bridge. The research shows both the damage index of Hilbert Marginal Spectrum Transfer Function and the damage diagnosis method of Support Vector Machine can be used to the damage diagnosis of long span cable-stayed bridge.