الفهرس | Only 14 pages are availabe for public view |
Abstract The use of nondestructive evaluation tools to assess the structural condition of bridge infrastructures gained wide acceptance. As a result, many countries direct their researches to this field. In this thesis, the most recent researches on nondestructive evaluation of the dynamic behaviour of box girder bridges are highlighted and the different concepts in this field are illustrated. Special attention is given to the application of modal testing as a global evaluation method of bridges. This includes the use of both frequency shifts and changes in mode shapes as indicators for damage presence. It was found that research was carried out in laboratories, and as a result environmental effects were not considered. With recommendations to carry out experimental tests in site, this study has three folds: The first focused on studying the dynamic characteristics of several prototype box girder bridges, including reinforced and prestressed concrete bridges. The study was performed analytically using the finite element analysis. Frequencies of vibration and mode shapes were determined and were compared to those of similar bridges available in the previous literature. In the second phase, the results of a dynamic test on a long-span prestressed box girder bridge were utilized to obtain its fundamental frequency and the corresponding mode shape. The process of obtaining these characteristics was thoroughly explained and applied. |