Damage Identification Of Bridge Structures Based On Wavelet Packet/wavelet Analysis Of Structural Responses

Structural health monitoring has been developed in recent years,which evaluates the condition of the bridge by using the response data of the bridge under different conditions.Wavelet analysis and wavelet packet analysis has good time-frequency analysis ability,relevant scholars have been using wavelet and wavelet packet method for a lot of research on bridge structural health monitoring,but the study also exists some shortage.This paper is aim at using the combination of wavelet packet/wavelet analysis methods and other methods to improve the shortcomings of the existing methods,so that we can evaluate the health of the bridge structure better,and provide a basis for the daily operation,maintenance and damage repair of the bridge structure.In the second chapter,the damage of the bridge is identified structure after earthquake quickly,which is based on the responses of the bridge structure under unknown earthquake.A method combining the wavelet packet energy with the transmissibility function is proposed to overcome the shortage of the wavelet packet energy method which requires the same excitation and the dependence of the traditional transmissibility function on the selection of frequency band.Numerical examples of simply supported beams and cable-stayed Bridges,as well as shaking table tests of cable-stayed Bridges,verify the effectiveness and feasibility of the method presented in this chapter.In the third chapter,a method of combining wavelet packet energy and relative entropy and moving strain sensors is proposed,only two sensors are needed to meet the requirements of damage identification.This method overcomes the existing nonbaseline damage identification methods’ shortcomings which need full observation of the structure.Numerical examples of simply supported beams and cable-stayed bridges verify the effectiveness and feasibility of the method proposed in this chapter.In the fourth chapter,using the response data of the bridge structure under moving loads to identify the damage of the bridge structure,and a method is proposed which combines discrete wavelet transform and independent component analysis,which only needs two sensors to locate the damage of the bridge,overcomes the shortcomings of wavelet methods that are susceptible to noise.Numerical example of a simply supported beam is used to verify the effectiveness and feasibility of the method.In the fifth chapter,the research content and innovation of this thesis are summarized and the prospect the work of future research.