The Research Of Structural Damaged Identification Based On Visual Measurement And Vibration Theory

Structural health monitoring(SHM)is the process of damage identification and damage calibration of engineering structures.The problem of structural health monitoring of bridge structures has always been a hot topic that scholars at home and abroad need to solve urgently.By monitoring the change of the structural modal parameters,the damage location of the structure can be located in time.This paper mainly studies the structural health monitoring of bridge structures based on visual measurement,engineering vibration theory and experimental modal analysis technology.Through the combination of simulation and experiment,verify the scientific of the algorithm.Its main work and results are as follows:1.The visual vibration measurement method is used to measure the full-field displacement of the simply-supported beam,and the non-contact full-field vibration measurement is realized,which reduces the cost,broadens the experimental range,and reduces the environmental impact.2.Introduced some current signal processing methods,and did computer simulation on them,and analyzed the advantages and disadvantages of each method.On the basis of variational modal decomposition,the permutation entropy algorithm is introduced,an adaptive noise reduction algorithm is implemented,and the scientific of the algorithm is verified through experiments.The index of this paper proposes a new indicator of similar smoothness,and the accuracy of this index is verified through experiments.3.Combined with the vibration theory,the theoretical reason for the modal node effect is derived,and a modal mode energy superposition algorithm is proposed to eliminate the modal node effect and overcome the amplitude "drift" phenomenon that occurs when locating multiple damage,Experiments have verified the scientific nature of the algorithm.4.Through experiments,it is found that there is a positive correlation between the degree of structural damage and the average energy difference of modal shapes.When carrying out actual bridge engineering structural health monitoring,the magnitude of damage at different locations can be calculated based on the magnitude of the average energy difference.The research results of this paper can not only locate multiple damages,but also eliminate the effect of modal nodes,and play a guiding role in the structural health monitoring of actual bridges.