Abstract
The behavior of a pier during earthquake is controlled by the relationship between the natural frequency of structure and the predominant frequency of input motion. The natural frequency of a full-scale preloaded and prestressed geosynthetic-reinforced soil pier of Umaide Bridge was evaluated by measuring the particle velocity at several points of the structure by applying an impact to the structure. The results showed that the natural frequencies in the normal and to in parallel to the girder axis were found to be about 7Hz and 9Hz, respectively. The measured natural frequencies of the pier were compared with those from small-scale model tests in the laboratory and their theoretical solution. The natural frequencies of the full-scale structure, were about a half of those in the models. It is inferred that the difference between the behaviors of the full-scale structure and the scaled model is due to the different base conditions, based on the deformable ground in the field and on a rigid plate in the laboratory.
