| Project/Area Number |
22K04280
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22020:Structure engineering and earthquake engineering-related
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| Research Institution | Saitama University |
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Principal Investigator |
Goit Chandra 埼玉大学, 理工学研究科, 助教 (10782732)
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| Project Period (FY) |
2022-04-01 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2023)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2024: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2023: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2022: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 1g model testing / SSI / impedance functions / kinematic responses / 3D FEM modelling / micropiles reinforcement / soil nonlinearity / Seismic retrofitting / Micropiles / Nonlinear response / Strong motion |
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| Outline of Research at the Start |
Seismic retrofitting of existing bridges that were designed based on the old design codes are necessary to meet the seismic requirements set forward by the revised design codes. Though many bridge piers were retrofitted over the years, only a limited attention was paid towards foundations. Damages seen after Kumamoto earthquake in 2016 revealed foundation failure even though the pier of the bridge was seismically retrofitted, signifying that retrofit of foundations is equally important. The proposed research aims at assessing the seismic performance of micropiles-retrofitted pile foundations.
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| Outline of Annual Research Achievements |
By the end of the academic year 2023, i.e., March 2024, all the experimental work that was originally planned for this research project have been completed. 1g model testing of micropiles-retrofitted pile foundations to elucidate the effects of nonlinearity on the components of soil-structure interaction (kinematic and inertial) was carried out. Results were quantified in terms of kinematic interaction factors and lateral pile-head impedance functions, for kinematic and inertial components of soil-structure interaction (SSI), respectively. Obtained results highlight some interesting insight into the behavior of micropiles retrofitted pile foundations, specially for pile-head impedance functions. Such pile-head impedance function are found to be dictated by the nonlinearity generated in the soil as a result of the loading amplitude (both static and dynamic cases) and the loading frequency (dynamic case). In addition, the influence of nonlinearity on the response of superstructure supported by foundations reinforced with micropiles was also experimentally obtained. Both the axial and bending strains generated in the piles were measured for all the experimental cases.
Three-dimensional modelling of the micropiles retrofitted pile foundations to clarify the experimentally obtained results of pile-head impedance functions was carried out. The numerical modeling confirms with the experimental results and indicate that soil nonlinearity plays a dominant role on the response, specifically at larger loading amplitudes.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
All the experimental work initially planned for this research project have been completed by March 2024. Data processing and evaluation of few select experimental cases involving seismic (under actual earthquakes) response of total system, i.e., considering superstructure, are yet to been carried out.
Few cases of numerical modelling to clarify experimental results have already been completed (few are to be carried out this academic year).
In terms of research presentations, though originally planned for 2023, such could not be materialized. However, instead, a journal paper was submitted and accepted (currently under typesetting stage). This year, i.e., 2024, research presentations at two events have been planned (submitted papers at both the event have been already accepted).
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| Strategy for Future Research Activity |
Data processing and evaluation of data for a few experimental cases (additional experiments carried out in the late last year for soil, pile, micropiles, and superstructure under actual earthquake loading) are still to be carried out. This year, firstly, such data processing for remaining cases are to be be carried out. Secondly, though few cases of numerical modelling related to pile-head impedance functions have been already carried out last year, there is a necessity for additional modelling (particularly for experiments with superstructure case), which will be carried out in this year.
Finally, based on the experimental and numerical data for experiments involving soil, pile, micropiles, and superstructure, submission for possible publication has been planned.
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