2003 Fiscal Year Final Research Report Summary
An advanced Research on the Structural Dynamics due to Short-Period Surface Waves with Emphasis on Applications to Practice
| Project/Area Number |
13650530
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
構造工学・地震工学
|
|---|
| Research Institution | Tohoku Institute of Technology |
|---|
Principal Investigator |
KAMIYAMA Makoto Tohoku Institute of Technology, Communication Engineering, Professor, 工学部, 教授 (50085461)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATSUKAWA Tadashi Tohoku Institute of Technology, Communication Engineering, Assistant, 工学部, 助手 (00165789)
|
|---|
| Project Period (FY) |
2001 – 2003
|
| Keywords | Surface wave / Short-Period / Pseudo-Spectral Method / Basin Structure / Love wave / Rayleigh wave / Nonlinear / 長周期地震動 |
|---|
| Research Abstract |
We have developed, some softwares for the earthquake response analysis of horizontally irregular grounds using the Pseudo-spectural method. Especially emphasis was placed on the introduction of nonlinear characteristics of soils as well as on the sophistications of programs. For the purpose of applications of our softwares to practice, we selected the irregular ground in Sendai City as a test site. Sendai City suffered severe damage due to the 1978 Miyagiken-Oki Earthquake. Since the earthquake, Sendai City has extended into areas composed of softer soils, increasing the anxieties of more devastating disaster by a great earthquake in the near future. In order to investigate strong-ground motions in Sendai, we installed there an array observation system of ground motions in 1997. The array system, named Snall-Titan, consists of 20 observation stations and one control center. Stimulated by the high seismicity in the Sendai district, the system has obtained many motion records resulting from a total of 250 earthquakes as of February in 2004. We first discussed observation results of ground motions in the Sendai basin from the point of view of local site effects, showing that amplifications of ground motions vary from site to site and arc remarkable in the soft deposit areas of the basin. The differences in amplifications between locations of the soft deposit areas were also analyzed. This analysis led to the importance of the edge effects of basin structure on the ground motions of the soft deposit areas. In order to make clear the mechanism of the edge effects, we modeled the Sendai basin using a two-dimensional Pseudo-Spectral Method. Based on-the model of basin structure, we made two-dimensional analyses of ground motions and compare the analyzed results with the observed. Comparisons show that the edge effects play an important role in amplifying motions in the soft deposit area of basin structure.
|
