2006 Fiscal Year Final Research Report Summary
Modeling of earthquake phase spectrum using a stochastic deferential equation and development of a simulation method of earthquake motion form phase spectrum
| Project/Area Number |
16360230
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | Kobe Gakuin University (2006)
Waseda University (2005)
Kyoto University (2004) |
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Principal Investigator |
SATO Tadanobu Kobe Gakuin University, Institute for Interdisciplinary Education, Professor, 学際教育機構, 教授 (00027294)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Ikumasa Musashi Institute of Technology, Civil Engineering, Professor, 工学部, 教授 (60409373)
MURONO Yoshitaka Railway Technical Research Institute, chief Researcher, 構造技術研究部, 主任研究員 (70425924)
FUNAKI Nobue Kobe Gakuin University, Institute for Interdisciplinary Education, Lecturer, 学際教育機構, 講師 (50434915)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Design Seismic Motion / Phase Spectrum / Group Delay time / Phase Modeling / Response Spectrum Compatible Motion / Hilbert Transformation / Phase Spectrum Compatible Motion / Modeling Group Delay time |
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| Research Abstract |
Both the amplitude and phase characteristics of earthquake motion provide key information needed to evaluate the aseismic capacity of designed structures. A method to simulate phase spectra is one of challenging topic in the design standard which is used to generate design earthquake motions compatible with the design spectra. We present a simple method for modeling the phase characteristic of earthquake motion based on group delay time and wavelet analysis. First the phase spectra are modeled for near and far source regions. Existing data sets of observed earthquake motions and wavelet analysis are used to calculate the group delay time of each earthquake motion. Regression equations for the mean group delay time and standard deviation of group delay time are obtained as functions of the earthquake's magnitude, epicenter distance and several source parameters. Simulating sample phase spectra assuming Gaussian nature of group delay time, earthquake motions compatible with the design response spectra then are simulated, and their characteristics investigated using ductility demand spectra. Second we develop a method to simulate realistic earthquake motions from phase spectra. The essential requirement of non-stationary time function such as earthquake motion is the causality. Because of this nature of earthquake motion its amplitude and phase cannot be assigned independently to simulate realistic earthquake motions. The restriction to be place on its phase spectra, however, has not been clearly defined to simulate a causal earthquake motion when its Fourier amplitude is given apriori. We develop a method to simulate earthquake motions from a given phase spectrum taking into account the causality restriction. Third we discuss a new method to simulate group delay time using the stochastic differential equation.
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Research Products
(10 results)
