Research On Damage Identification Of Frame Structure Based On Frequency Response Functions

There are different degree of damage when building structure is in service,which is a potential hazard and may cause accidents.Identification of structural damage is an important part of the monitoring of structural health.Getting a method of structural damage identification that have higher accuracy is of great significance.Frequency response function is determined by the stiffness,mass and damping,any changes in these three parameters are reflected in the frequency response function.The location and degree of structural damage will result in changes of frequency response function.Research shows that the frequency response function is sensitive to the fault of structures and can reflect the dynamic characteristics of structure,thus it can be used as characteristic parameters of damage identification.At present,the structural damage identification based on dynamic test is the hotspot and difficulty in research at home and abroad.The basic idea of structural damage identification based on the vibration information is expressed as follow.Through applying incentive we can get the dynamic response of the structure,and then analyze the dynamic characteristics of the structure.Through the analysis of the change of the structure dynamic characteristics,we can acquire the information of structure damage,and then continue structural damage identification.In this paper,a kind of damage identification method based on the frequency response function were studied The method is effective to qualitative identification,positioning identification and quantitative identification of structural damage.The method can be generally divided into three phase.First,by observing whether the frequency response function has changed curves before and after the damage,and the qualitative result of structural damage can be made;Second,by looking the damage index of different degrees of freedom structure damage position can be finished;Finally,according to the quantitativecalculation formula of damage,we can calculate the damage degree of the damaged units which has been awarded the second step.In this paper,the fourth chapter conducts damage identification of numerical simulation and experimental research,in allusion to a plane frame structure.In the numerical simulation for a variety of types of injuries respectively carried out qualitative identification,positioning and quantitative identification.Damage identification results of the single or mutiple cell in different location is ideal and especially quantitative results are accurate,which shows that the method is effective in theory,can solve the problem of damage identification in practice.In order to verify the theory and method for solving the practical problems that may occur in the damage identification,a set of steel frame that is assembled by units is designed,the structure model is then used to identify the damage by experimental method.According to different damage,experiments were researched.The results show that the frequency response function is extremely sensitive and small damage can also be clearly represented.In this paper,the theoretical and experimental research for the actual building structure damage identification and health monitoring provides some reference idea and helps to solve the related problems in practice.