Structural Damage Identification Based On Ensemble Empirical Mode Decomposition And Hilbert Transform

In this paper,the structural damage identification is carried out by analyzing the structural vibration response obtained from the test.Starting with the time-frequency domain theoretical analysis of the structure,the damage index is constructed according to the instantaneous frequency spectrum obtained from the analysis.The effectiveness and applicability of the damage index are studied through numerical simulation and experimental measured data,so as to achieve the purpose of accurately identifying structural damage.Firstly,this paper introduces the research status of structural damage identification at home and abroad,summarizes the commonly used damage identification methods,compares the advantages and disadvantages of various methods,and selects Hilbert Huang Transform(HHT)method as the signal processing method for structural damage identification.In order to reduce the mode aliasing effect and improve the calculation accuracy,the Ensemble Empirical Mode Decomposition(EEMD)is used to replace the Empirical Mode Decomposition(EMD)in the traditional HHT method to obtain the Intrinsic Mode Function(IMF)with higher quality.Secondly,through the integrated Empirical Mode Decomposition and Hilbert Analysis of the acceleration response of multiple analog signals and nonlinear systems,the instantaneous frequency of the signal can be accurately reflected in Hilbert spectrum and marginal spectrum,and then the damage characteristic index based on marginal spectrum is constructed.The proposed damage identification method is used to simulate and analyze the benchmark structure.In the analysis and research of various damage conditions,it is found that among the four damage indexes based on marginal spectrum,the energy cumulative variation index(DI)and the maximum energy variation index(RI)have better accuracy and reliability.Finally,the method of this paper is used to analyze the steel beam data in the laboratory and the vibration monitoring data of Shenzhen Zhongzhen building.By analyzing the acceleration response of the test steel beam,the damage index is constructed,and the changes of the damage index in the undamaged state and the damaged state are compared.It is found that the damage index changes the most on the No.1 unit of the structure,so as to identify the damage of the test steel beam structure near the No.1 unit,which is consistent with the actual situation.By analyzing the acceleration response of the Zhongzhen building in x and y directions,it is found that there is no obvious extreme value of the damage index in the continuous monitoring,indicating that the health status of the Zhongzhen building is stable and there is no structural damage in this period.The analysis results of test steel beams and Zhongzhen buildings show that this method is feasible in practical engineering structures and has practical engineering significance.