| 種別 | paper |
| 主題 | Identification of Stiffness Deterioration of Concrete Structures |
| 副題 | |
| 筆頭著者 | Andres W.C. Oreta（De La Salle University） |
| 連名者1 | Masami Ishikawa（Tokyu Construction Co.） |
| 連名者2 | Tada-aki Tanabe（Nagoya University） |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 16 |
| 号 | 2 |
| 先頭ページ | 1289 |
| 末尾ページ | 1294 |
| 年度 | 1994 |
| 要旨 | 1. INTRODUCTION Experiences from past strong earthquakes have shown the vulnerability of civil structures to strong ground shakings. Even in the case of mild earthquakes or under normal loading conditions, some level of damage is expected in structures, especially in concrete structures which deteriorate due to many factors such as creep, corrosion of reinforcements and microcracking. In this regard, in order to assess the soundness of these structures, both qualitative and quantitative analyses must be done. Recently, the authors developed the local identification for framed structures using Kalman filter and showed its numerical feasibility in the identification of the stiffness characteristics of individual members of plane frames. Local identification has practical importance since damage is local in nature and damage in a few critical members significantly affects the deterioration level of the complete structure. The applicability and limitations of local identification when real structures are analyzed have still to be verified though. Therefore, an experimental investigation is conducted and presented in this paper. The authors performed the shaking table test of a reinforced concrete space frame at the vibration laboratory of the Institute of Technology of Tokyu Construction Co. The accelerations and strains at critical locations of the specimen were measured and used as input and observations for the purpose of structural identification by Kalman filter. To observe the deteriorating condition of the specimen, the dynamic properties such as modal parameters and the stiffnesses of the members were identified at different stages of the structure. Results showed that system identification can be used in order investigate the deteriorating behavior of the structure as it accumulates damage due to intense ground oscillations. 4. CONCLUSION The results of the present study showed that the deterioration of the structure can be observed by the system identification approach. Modal identification showed the deterioration of the structure as reflected by the decrease of its fundamental frequency with the accumulation of damage. Local identification, on the other hand, illustrated the apparent reduction of the stiffness of column members with damage and the nonlinear behavior caused by damage due to the formation of cracks, spalling of concrete, and shear cracks in the beams. In general, the identified parameters showed the deteriorating trend of stiffness characteristics of the structure. |
| PDFファイル名 | 016-01-2215.pdf |