Study On Damage Identification Of Concrete Structures By Dynamic Parameter Method

Because of various factors, damage, which will lead to serious consequence, will inevitably appear in civil engineering structures. Therefore, it is necessary for engineering structures to be monitored for health. Structural Health Monitoring (SHM) and Restoration is a focal point of National Nature Science Foundation of China in civil engineering field. It is also a hot subject in international engineering field presently and has very important engineering background and practice value. SHM includes damage identification and capability evaluation. Theory and method of damage identification of structures is the research core of SHM. In this thesis, research about damage identification of structures is carried on with the emphasis on the study of dynamic parameter method based on vibration. The main contents are summarized as follows:1. Some damage identification methods of structures in common use are discussed. The procedure of damage identification methods based on vibration is mainly analyzed. That finding the dynamic parameters which can indicate structural damages sensitively is the key point of the method is emphasized. Dynamic parameter determines success or failure and effectiveness of the damage identification methods.2. In the damage identification method based on vibration, the modal analysis of healthy R.C. structures by FEM is often needed. After the discussion of analysis method of R.C. structures by FEM in common use, the model analysis method of R.C. structures based on FEM program ANSYS is studied. Because nonlinear character of materials can't be taken into account in modal analysis in ANSYS, the modal analysis of R.C. structures by ANSYS can only get approximate result.3. The dynamic parameters which are commonly used in damage identification are mainly discussed, such as curvature mode, rotation angle of mode shape, flexibility matrix, flexibility curvature, strain mode, modal strain energy and so on. Their characteristics and applicability are studied and verified by some numerical examples or structural experiments.4. The identification capacity of different dynamic parameters, which includes capacity of identifying early damages, damages of different degrees and positions, is numerically analyzed. Certain dynamic parameters which can identify early damages or damages of different degrees and positions of structures are found out.5. The dynamic parameters mentioned in the thesis are overall evaluated based on the summarization of the analysis of dynamic parameters in the whole thesis, such as their theory, difficulty in practical application, advantage and disadvantage and so on. Some useful references are presented for damage identification in practical structures.