Study On Damage Identification Of Structures Based On Incomplete Practical Information

Structural Health Monitoring (SHM) and Restoration is a focal point of China in civil engineering field. It is also a hot subject in international civil engineering field presently and has very important engineering background and practice value. In this thesis, research about damage identification of structures is carried on with the emphasis on the study of damage identification based on incomplete practical information. The main contents are summarized as follows:1. The main methods of structural damage identification and the flow of experimental modal analysis were studied. The modal theory of damage identification based on liberation and its realization in finite element method was particularly analyzed. The correctness of modal analysis in ANSYS was validated.2. This thesis with use of numerical analyzes, indirectly got full information of parameters that damage identification methods used based on flexibility mode shape by mode expansion. Then, the effectiveness of modal strain energy and methods based on rotation angle of mode shape that are used on a fixed beam which was damaged in the middle was numerically validated and compared with the full information expanded and theoretical full information. Result indicates that the expansion full information and theoretical full information all could be used to identify damage, and showed good effectiveness. In this way, modal strain energy and methods based on rotation angle of mode shape could be used in practical engineering; the problem of incomplete practical information was solved.3. For the frame structure, the method of curvature mode show good effectiveness on damage identification except the node element. However, because of self-limitation of the curvature mode method, it can not identify the node element of the frame structure. Modal strain energy method in the use of frame structure has been studied aimed at the node element damage. Result indicates that the method of modal strain energy could correctly identify the frame structural damage in different degree and in different place which include node element. It shows that the method of modal strain energy is more adapt to frame structural damage identification.