Research Of Structural Damage Identification Based On Wavelet Transform

Since the new China,a large number of infrastructure has been built,and now many structures have been put into use for decades,which are prone to damage due to fatigue;new structures are also increasingly developing to large-scale and complex,once an accident occurs,it will cause huge economic losses.A large number of researches have begun to combine sensors and computers to carry out real-time health monitoring of structures,and wavelet transform is one of them.In many researches of structural damage analysis based on wavelet transform,the model is one-dimensional bridge model.But in reality,there are many three-dimensional structures,such as station,which include not only one-dimensional beam and column structure,but also two-dimensional plane structure.In this paper,the method of wavelet transform is selected to monitor the damage of the plane by arranging sensors on the outgoing floor of the model of Xiangyang east railway station.Its main work includes.(1)The principle of wavelet transform method is explained,and the commonly used wavelet functions are introduced.(2)The acceleration sensors are arranged in the horizontal and vertical directions of the outbound floor,and the reasonable number of sensors is selected.(3)In practice,it is impossible to detect the excitation of the structure,only to get the response.Therefore,in this paper,the cross-correlation processing of model sensor data under white noise is carried out by using natural excitation technology,and the multi-order modal parameters of the structure are automatically extracted by calculating the power spectrum,smoothing data,threshold processing and so on.(4)The signal used to identify modal parameters is required to be stationary,otherwise the identification results are not accurate.Therefore,two kinds of different abnormal load data are used to act on the structure,and the obtained acceleration response is identified as abnormal signal.(5)After the structure is damaged,the acceleration of the position will change,which will lead to the change of the vibration mode data identified by the acceleration.In this paper,discrete wavelet transform is used to identify the vibration modes of damaged structures.By comparing with the wavelet transform coefficients of healthy structures,the relative changes of wavelet coefficients are calculated to determine the damage location.(6)Lipschitz Index has the characteristic of identifying data singularity.Using the wavelet coefficients of damage location for Lipschitz Index calculation to judge the damage degree of the structure.Through the calculation of wavelet transform damage identification under different working conditions,a better method for damage identification of two-dimensional plane structure is obtained,which is of great significance for real-time health monitoring of structure.