2019 Fiscal Year Research-status Report
Development of a low-damage, high redundancy vibration control structure system considering extreme ground motions
| Project/Area Number |
19K15139
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| Research Institution | Hiroshima University |
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Principal Investigator |
陳 星辰 広島大学, 工学研究科, 助教 (00816564)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | Spine frame / Displacement restraining / Cyclic loading test / Time-history analysis |
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| Outline of Annual Research Achievements |
This research aims to develop a low-damage, high redundancy vibration controllable system, namely displacement-restrained spine frame system. In the first year, detailed concept of the structural system was proposed and its structural characteristics were clarified through static loading tests and dynamic analysis. (1) Firstly, static hysteresis characteristic of the system and the prerequisites of eliminating undesired vertical residual deformation have been clarified based on theoretical analysis. The theoretical results were validated through static numerical analysis, and will be further validated by dynamic analysis and loading tests. (2) Furthermore, dynamic characteristics of full frame models were studied by using time-history analysis. Displacement restraining function was preliminary verified through a low-rise building model and limited ground motions. (3) Moreover, static cyclic loading tests were carried out to validate the structural behaviors with various initial gaps at the column bases and damper configurations, as well as feasibility of the special pin-connection between the spine frame and the foundation beam. Dampers also exhibit smooth behaviors between the small vibration stage and large vibration stage. Generally, the test results were in good agreement with the theoretical prediction.
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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
The research is generally carried out as originally planned. (1) The ideas of displacement restraining methods have been extended to several more ideas besides the original proposal. The original idea in the application forms was to supplement displacement restraining members at the side base of the spine frame without releasing connection between the spine and the foundation. However, this method might induce large shear force in the spine frame and cause expected damage. Besides this idea, some other promising ideas were proposed and tested in this year, such as making use of self-weight of the spine frame or adding post-tensioned strands, meanwhile allowing uplifting at the base of the spine frame. The new approaches might reduce shear demand of the spine frame. (2) The research objectives scheduled in the first year and the second year are actually both involved in the first year. The original plan of the first year is to suggest suitable displacement-restraining elements, and plan of the second year is to clarify engineering demands of the main structural components. When the displacement-restraining elements were tested and compared, extensive numerical analysis were conducted to search the applicable range of some key parameters, such as the size of initial gap, stiffness and initial stress of steel strands. Although the selection of displacement-restraining elements is still ongoing, research works in the next stage are also carried out simultaneously.
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| Strategy for Future Research Activity |
(1) Loading tests of spine frames with steel strands will be conducted in the second year. Feasibility and efficiency of supplementing strands will be verified. Besides, the theoretical prerequisites of eliminating undesired vertical residual deformation will be further verified by using experimental results. (2) In order to simplify the analysis, full frame models were equipped with small dampers in the numerical analysis in the first year. One of the main advantages of the new proposal is the additional energy dissipation during small vibrations, which has not been presented in the current models. This feature will be investigated in the next year through numerical analysis with larger dampers. (3) Moreover, difference between the original proposal and the modified proposal is not clear yet. Their performance will be compared considering the effect of shear stiffness of spine frames. The suitable application conditions will be clarified for each proposal. (4) Investigation on the effect of main structural parameters will continue in the second year. Besides the parameters concerned in the application forms, there are several new parameters need to be considered. Parametric loading test and numerical analysis will be carried out to clarify the demands and optimal scopes of the main parameters. The input ground motions will include various types of earthquake waves such as long period, long duration, pulse waves components. (5) Plan for the last year is expected to be carried out following the original application, to establish a design approach for the proposed system.
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| Causes of Carryover |
One reason for incurring amount is that the amount allocated for the first year was larger than those allocated for the following years. Moreover, the research contents in the first year were mainly theoretical and numerical analysis with a few of experiments. More experimental tests will be conducted in the following years. Therefore, some amount was not used in the first year and it was saved intentionally for the upcoming tests in the following research periods.
The usage plan is as follows. Firstly, cyclic loading tests will be conducted on specimens with additional displacement restrainers and with various configurations. Besides the full specimen tests, some coupon tests and partial specimen tests will also be carried out to understand the individual behaviors of some key components including the displacement restrainers. Moreover, extensive numerical analysis will also be conducted, which will need some amount for analysis related software for data process as well as PC related devices. Some of the amount will also be used for supporting publication as international journal papers and registration for both domestic and international conferences.
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Research Products
(3 results)
