Study On Damage Identification Method Of The Frame Structure Based On Wavelet Packet Energy

During the period of service,the frame structure is affected by factors such as load,material aging and fatigue effects,and even earthquakes and blasting impacts,which inevitably lead to structural damage,and the accumulation of damage to a certain extent may lead to the sudden destroy of the overall structure,resulting in huge economic losses and casualties.The damage identification method of the frame structure is studied to determine the occurrence of structural damage and the specific location of the damage,thereby repairing or reinforcing the structure.It is important theoretical and practical value to ensure structural safety.The main contents and results are as follows:(1)Based on the statistical properties of wavelet packet energy eigenvectors,the paper uses Wavelet Packet Energy Feature Vector Mean Difference(EVMD),Wavelet Packet Energy Feature Vector Standard Deviation Difference(EVSD),Wavelet Packet Energy Feature Vector Mean Difference Curvature(EVMDC)and Wavelet Packet Energy Feature Vector Standard Deviation Difference Curvature(EVSDC)as the damage identification index.By identifying the damage of a two-layer 1×1 span space frame structure numerical model,the damage identification difference based on the wavelet packet energy distribution index and the wavelet packet energy size change index is studied.The results show that the recognition curves of EVSD and EVSDC based on the energy distribution of wavelet packet are similar to those of EVMD and EMVDC based on the change of wavelet packet energy respectively,and the recognition effect of the former is more obvious than that of the latter.(2)Based on the analysis of the limitations of EVMD,EVSD,EFMDC and EVSDC,a better performance identification index,namely the wavelet packet energy eigenvector standard deviation relative deviation(EVSDR),is proposed,so that the EVSDR-based damage identification method is proposed.The effects of the excitation position,response recording direction,excitation form and environmental noise on the damage of the method are investigated.The results show that the EVSDR-based damage identification method can identify the damage of the frame structure at any position,and the damage recognition effect is optimal with the axial response of the component.The damage recognition effect is less affected by the excitation position and is greatly affected by the excitation form and environmental noise.(3)The EVSDR-based damage identification method is applied to the experimental model and numerical model of the IASC-ASCE benchmark model and compared with the recognition effect of the similar damage identification method to verify the damage identification ability of the method.It is found that the EVSDR-based damage identification method can identify the part of the damage condition of the test model,and the full damage condition of the numerical model in the IASC-ASCE reference model.By compared with a similar damage identification method,it is more suitable for the damage identification of the IASC-ASCE reference model.