1996 Fiscal Year Final Research Report Summary
Spatial Variation of Ground Motion and Its Effect on 3-D Response of Structures.
| Project/Area Number |
07680480
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster science
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| Research Institution | Miyagi National College of Technology (1996)
Tohoku University (1995) |
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Principal Investigator |
SHIBUYA Jun-ichi Miyagi National College of Technology, Dept. of Architecture, Professor, 建築学科, 教授 (70005461)
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| Co-Investigator(Kenkyū-buntansha) |
YUSA Masaki Tohoku University, Fac. of Engineering, Res. Staff, 工学部, 教務職員 (00260422)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Ground Motion / Array Observation / Spatial Variation / Coherence / Soil Amplification / Inhomogeneous Soil / Multiple Input / 3-D Response |
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| Research Abstract |
(1) Analysis of Spatial Variation of Ground Motion from Array Observation in Tohoku University.
Spatial variation of ground motion is evaluated by means of the coherence function using the seismic array records of the four observation stations in the Tohoku University site. The total length of the array is about 1km. Average coherence of the ground motion in the site shows a rapid decay with the increase in the frequency and the separation distance. The decay of the coherence per one wave-length of S wave is about 0.3 to 0.4. The surface soil amplification, defined as the spectral ratio of the record at the soil station to that at the rock station, shows a remarkable fluctuation depending on the earthquake event. The coefficient of variation of the fluctuation can be interpreted by the coherence of the ground motion.
(2) Numerical Analysis of the Spatial Variation of Ground Motion using Inhomogeneous Soil Model.
Spatial variation of the ground motion is evaluated by means of coherence fun
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ction using a calculated surface response of a finite element model of the ground with random soil stiffness. Parameters of the study are the coefficient of variation and the correlation length of the random S wave velocity of the soil. It is found that the coherence decays with the increase in the coefficient of variation and with the decrease in the correlation length of the S wave velocity of soil. The analytical coherence from the model with a coefficient of variation, 0.3, and a correlation length, 20m, agrees well with the observed coherence.
(3) 3-D Response Analysis of Structures Subjected to Spatially Varied Ground Motions.
A 3-D response of a one-story building model with a one-bay by one-bay frame subjected to ground motions which are spatially varied at the bases of four columns is analyzed. Parameters of the study are the span length and the natural periods of the building model. As the span length increases, the translational response at the center of the model decreases but the torsional response increases. This is considered to be an averaging effect of the structure and the effect of torsional component of input motions. Maximum response of the column, which is the result of translational and torsional responses of the model, decreases as the span length increases. Less
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Research Products
(10 results)
