Dynamic Behaviors And Damage Identification Of Structures

Most of structures work with damages, and the presence of damages will lead to the change of their dynamic behaviours. Therefore, it is important to study the dynamic behaviours of structures with damages. Presently, the traditional finite element method using approximate shape functions are commonly used for the study in the literature. However, errors arise due to the model approximation.In this thesis, the dynamic behaviours of frame structures with damages are analyzed and an exact finite element method based on dynamic stiffness is used. The damages are considered as smeared ones, and therefore can be modeled as the reduction of bar stiffness. Exact frequencies, modal shapes and curvature mode shapes of frame structures with damages are obtained. The effects of damage location, severity of damages and multiple damages on the dynamic behaviours are analyzed.Then, damage identification is discussed. A new method------patch-test method is proposedand used to identify whether cracks have occurred. Further, Genetic Algorithms are used to identify the location and severity of damages. Numerical examples show that the above methods can achieve good results.