Damage Identification Of Local Structures Based On Additional Virtual Physical Parameters

The structure can be affected by various factors in its complex service environment,which leads to local damage of the structure,such as joint damage to the frame structure,crack damage on the beam and bridge cable damage,etc.These local damages may become a potential danger to the safety of the structure.However,the vibration information of the structure is not sensitive to the local damage and the dynamic responses of the structure is insufficient.Based on the above considerations,this paper proposes a method of adding virtual physical parameters to the structure,and gives a study on three kinds of structural local damage.Damage identification of semi-rigid joints based on additional virtual mass.First,the semirigidity of beam-column connections is taken into account,and gives a way to build a finite element model that the semi-rigid element is regarded as a basic mechanical element.Then a three-story two span steel frame model is built to analyze the influence of semi-rigid joints on the overall modal information of the structure.After a reasonable semi-rigid range of the joint is selected,the virtual structure is constructed by adding virtual mass near the damaged joint.Finally,the accuracy of damage identification is improved by increasing the number of virtual structures and the sensitivity of structures to joints damage.Damage identification of crack based on additional virtual mass.First,the classification and characteristics of current crack simulation methods is briefly introduced.Then,use the numerical simulation of crack damage finite element model to analyze the sensitivity of structural modal information to crack damage.Furthermore,the additional virtual mass method is used to identify the damage of the cracked beam structure.Finally,using twice optimization solution method,the better damage identification results can be obtained by determining the crack location before identifying the damage degree.Damage identification of cable based on additional virtual support.Firstly,the basic theory of isolated substructure method of virtual support is introduced.Then virtual support is added to the cable to separate the cable substructure from the global structure,so that the damage identification of cable can be transformed into the damage identification of cable substructure,which weakens the influence of cable boundary conditions and cable length on cable force.Finally,the response of the cable isolated substructure is constructed to identify the damage,which improves the sensitivity of the bridge structure to the local damage of the cable.In this paper,for different types of structural damage,considering the characteristics of the structure and damage,the physical parameters that to be added are different.The numerical simulation and experimental analysis show that damage identification methods based on additional different physical parameters can achieve better results,which proves that the damage identification method based on additional virtual physical parameters is widely applicable to local damage of real structures.