Time Domain Damage Identificationmethod For Bridges Based On Dynamic Environment Excitation Responses

In recent years,along with the rapid development of economy,technology,largescale bridge construction has achieved remarkable results.At the same time,because of the long-span bridge itself features significant problems,it leads to all kinds of collapsed events arose endlessly and poses a serious threat to the state property and people's life safety.In order to guarantee safe operations of large bridge structure,real-time control of bridge safety status,and establishing a proven bridge-damage identification method are very necessary,for they are of practical value and scientific significance to the bridge engineering in China.This article is based on empirical mode decomposition(EMD)and the markov distance theory offers a way to use the environment excitation response time domain method to recognize the damage.The article First introduces several important methods of damage identification,and analyzes their respective advantages and disadvantages.Secondly it introduces the empirical mode decomposition and the basic theory of mahalanobis distance,and introduces the mahalanobis distance depending on the damage identification classification,on this basis,the cumulant(MDC)is established by mahalanobis distance of damage identification index,uses the probability density function of the MDC based damage identification threshold,and puts forward the previous order of intrinsic mode function more advantageous for structure damage identification.Then It simply supports beam and the cable-stayed bridge finite element model is established to the incentives of sine force,by changing the elastic modulus of a unit to simulate structural damage,and damages identification and positioning,to verify the effectiveness of the proposed method and the noise resistance.Behind by beams model damage identification test,through the analysis of its strain processing,using MDC is good enough to identify structural damage and damage location,verify the effectiveness of the proposed damage indexes in actual situation.Finally,it uses the strain response of the bridge monitoring,adoptes a drop sampling data processing method,effectively accelerates the process of damage identification,and after using the EMD decomposition of structure,the damage index of the intrinsic mode functions by MDC determine whether it damages the probability density in distribution function.