Seismic Risk Evaluation in Densely Populated Area
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
Structural engineering/Earthquake engineering/Maintenance management engineering
|Research Institution||Meisei University|
TOSHINAWA Takumi Department of Architecture, Meisei University, Professor, 理工学部, 教授 (00188749)
|Project Period (FY)
2005 – 2006
Completed(Fiscal Year 2006)
|Budget Amount *help
¥3,300,000 (Direct Cost : ¥3,300,000)
Fiscal Year 2006 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 2005 : ¥2,800,000 (Direct Cost : ¥2,800,000)
|Keywords||Evaluation of seismic risk / Ground-motion characteristics / Vibration characteristics of buildings / Resonance / Microtremors / 強震観測 / 地震危険度|
1. Microtremor measurements on the ground in densely populated area
In the densely populated area concerned herein, three-component microtremors on the ground in the period range shorter than 1 sec were collected with spatial intervals of 25-50 m. H/V spectra were obtained for each points and the distribution of natural period of subsurface soils were evaluated. The results showed that the natural period of the ground was shorter in the northern area whereas the period becomes longer in the southern area. The shortest period is less than 0.2 s and the longest period is longer than0.5 s.
2. Evaluation of natural periods of buildings
In order to obtain natural period of the buildings in the area, microtremor measurements were conducted on the top floor of 27 RC/S/SRC buildings. The natural periods evaluated form the measurements were correlated well with the periods predicted from empirical relationships between natural periods and building heights demonstrating that natural periods of buildings in the area can be predicted form buildings heights.
3. Field survey of the number of stories and structural types of buildings
The numbers of stories and structural types of 9520 buildings in the area were evaluated through field survey showing that 70% of buildings were 2 story-wooden houses.
4. Evaluation seismic risk map of the area
From the distribution of the natural period and a frequency-response curve of SDOF system, a seismic risk map of buildings is evaluated for each natural period of buildings. The results show that seismic risk for buildings with the natural period of 0.5 sec is high in the south of the station while the risk for 0.3 sec is high in the north of the station. The former result is consistent with the distribution of damage to buildings in the 1854 and 1923 events.
Research Products (4results)