Structural Damage Identification Based On Cosh Spectral Distance And Transmissibility

Recently, many new theories and methods of structural damage identification are presented under the concerted efforts of scholars at home and abroad, which drastically promote the development of structural health monitoring. While the development of research is relatively sluggish and can’t effectively guide engineering practice due to the limit of level of awareness of people, the technology of experiment and site conditions. It is important to find a more accurate and reliable method of structural damage identification method which can be applied to practical engineering more effectively.According to those problems, in this paper, numerical simulation model of simply supported H-beam is established and field test applied with hammer load as external excitation. And then a damage identification method based on Cosh spectral distance by means of time series analysis against output response of structure is proposed in this paper. Auto-regression(AR) mathematical model is developed for acceleration response of structure under intact and different damage condition via MATLAB. The Cosh spectral distance, which is taken as a damage index to identify the performance level of structure, is calculated by using the values of model residual sequence and compared with other damage indices(Itakura distance etc).And then, in terms of the dynamic output response of the structure, the structural damage identification method based on the transmissibility is introduced, which use response data of the acceleration time history of undamaged structure are taken as benchmark reference data, while the time history responses data of the structure under different damage conditions are taken as test data. The respective transmission rate is calculated by these data, which is taken as a parameter to calculate the different damage index. And then the DDI and ARI index related to the damage index are introduced to identify the performance level of structure. Comparing the results of several damage indexes, the advantages of this index in damage identification are studied.Finally, with the concept of transmissibility, the TDI index, which is used to identify the degree of damage of structure, is calculated on the basis of RVAC index after fast fourier transformation about collected acceleration time history response. The correlation and effectiveness of the TDI index to structure damage is discussed by comparing the values of TDI of different hammering point.It is worth mentioning that the structural damage identification methods introduced in the paper can avoid the measurement of input excitation, directly use the collected acceleration response to identify structural damage. Comparing with conventional structural damage identification method, it’s not need to establish numerical simulation model and can process follow-up work more efficiency. At the same time, the damage indices introduced in this paper have stronger anti-noise property.