Complexity Pursuit Identifies Structural Parameter And Damage

In recent years,the scale of investment in national infrastructure construction continues to expand,a variety of large and complex structures are emerging.During their service,damage inevitably occurs by external factors and their own.In order to detect structural damage early and reduce the threat to people's lives and property,an effective means is to install a health monitoring system on a large structure.As the core content of structural health monitoring system,structural parameter identification and damage identification have been the focus of research among domestic and foreign scholars.They are trying to find a method of damage diagnosis for large-scale complex structure on-line monitoring.In this paper,the complexity pursuit algorithm is applied to the modal parameters and damage identification of civil engineering structure,which provides a new idea for the field of structural recognition,enriching and perfecting the theory of structural health monitoring.The contents and achievements of this paper are as follows:(1)Expounds the research background and significance of this subject,discusses the research methods and existing problems of current structure modal parameter identification and damage identification,and briefly introduces the development of blind source separation and its application in structural recognition.(2)This paper briefly introduces the related mathematical knowledge,basic principle and preprocessing method of complexity pursuit,and discusses the establishment of objective function and gradient optimization algorithm.The original gradient algorithm iterative process uses fixed step size and non-linear function,making the algorithm is not adaptive.In this paper,the iterative process of the original gradient algorithm is improved according to the kurtosis and the optimal step size,and the adaptive complexity pursuit algorithm with better applicability and better separation effect is formed.(3)A new method of complexity pursuit combining Hilbert transform to identify modal parameters is developed.The relationship between the dynamic response and the complexity pursuit model of the multi-degree-of-freedom structural system is discussed.The modal responses and modal shapes of the structures are separated by the complexity pursuit algorithm.Then,the Hilbert transform is used to analyze the modal frequency and damping ratio.Through the different models,it is verified that the method can accurately identify the structural modal parameters.(4)A new method of complexity pursuit combining ensemble empirical mode decomposition to identify structural damage with is developed.Structural damage can cause the mutation of the response signal.The intrinsic mode function with high frequency containing the damage component is extracted by the ensemble empirical mode decomposition,and the damage component is separated from the noise signal by using the complex tracking algorithm.According to the position of the signal mutation point to identify the time of injury occurred,and then identify the location of damage based on the hybrid matrix.Through the different models,it is verified that the method can accurately and effectively identify the time and location of structural damage.