Structural Damage Detection Of Transmission Tower Utilizing Ambient Vibration Data

Structural damage detection in large-scale three-dimensional spatial structures is achallenging problem. It is impractical to develop a general damage-detection methodthat is applicable to all types of structural systems and all kinds of damage. A practicaland efficient structural damage detection method must consider the characteristics of thetarget structure and damage in the development stage. The paper proposed a damagedetection method for the health monitoring of transmission towers. The method wasdeveloped based on the dynamical finite element (FE) model reduction technique,which utilizes identified modal parameters, such as natural frequencies and modeshapes, with only a limited number of sensors. To reduce the required computationalpower, two simplified versions of the proposed method are presented. The proposedmethod is then verified with a Two-dimensional truss structure, a Three-dimensionaltruss structure and the Transmission tower.In order to identify accurately the modal information about the transmission tower,This paper uses the NExT-ERA method based on the characteristics of natural excitation.In the process of modal identification of transmission tower, this paper adopts theimpact load which is used to simulate the natural excitation, and measure theacceleration response of the nodes with Wilson-θ method which instead of accelerationsensor. Through the NExT-ERA method with the acceleration response to identify thelast modal,this paper uses the singular value difference method and different entropyincrement method to make the system order determination, also take two index whichare MAC and MPC to eliminate false modes.The main conclusions are as follows: The NExT-ERA method based on thecharacteristics of natural excitation can successfully identify the first two order modesof the transmission tower structure, but the reasonable order must be determined inapplication, to ensure that no modal is lossed and spurious modes aren’t too much. Themethod of θ index damage identification based on model reduction is applicable togeneral two-dimensional and three-dimensional truss structure, and it is suitable fortransmission tower structure. whether in the damage location identification andquantitative recognition, it has a very good performance. First simplified method hasvery good performance on damage localization and quantitative identification in thetwo-dimensional truss. For the three-dimensional truss, first simplified method can only be used to identify the damage location. Second simplified method only can beapplied to identify the damage location of two-dimensional truss.