2020 Fiscal Year Research-status Report
Development of a low-damage, high redundancy vibration control structure system considering extreme ground motions
| Project/Area Number |
19K15139
|
|---|
| Research Institution | Hiroshima University |
|---|
Principal Investigator |
陳 星辰 広島大学, 先進理工系科学研究科(工), 助教 (00816564)
|
|---|
| Project Period (FY) |
2019-04-01 – 2022-03-31
|
| Keywords | spine frame / post-tensioning / steel strands / cyclic loading test / time-history analysis |
|---|
| 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 second year of this research project, the concept of the proposed structural system has been further improved through adding post-tensioning steel strands at the spine frame to ensure sufficient displacement restraining effect. Static cyclic loading tests were carried out for specimens consisting of rocking-delayed spine frames, steel dampers, and steel strands. The experimental parameters included the initial gap at the spine frame column base, steel strands configurations, and damper yield strength. Evaluation method for the lateral force-displacement relation was established based on the analysis of structural properties of each component. The test results were generally in good agreement with the evaluated results. Furthermore, the occurrence of vertical residual displacement during the cyclic loading has also been well predicted through using the theoretical analysis carried out in the first year. The experimental study verified the feasibility and static behavior of the improved structural system as well as the evaluation method. Time-history analysis is ongoing to investigate the seismic behavior of the proposed system.
|
| 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 concept of the displacement-restraining spine frame system is almost determined based on the first two years experimental and numerical investigations. Compared to the original idea, the new concept could provide much flexible adjustment of the spine frame system according to the design demands, including the uplifting force and the post-uplifting stiffness. Static behaviors of the proposed system have been extensively studied by static cyclic loading tests on two suits of specimens with various parameters.
The original plan of the second year is to clarify engineering demands of the main structural components, while that of the third year is to establish a design approach for the proposed system. Although it took longer time including two suits of static loading tests to determine the configuration and components of the system, time-history analysis focusing on the dynamic performance and engineering demands of the proposed systems have been carried out simultaneously. Evaluation methods for static lateral force-displacement relation of the system has also been established, which is the first step for proposing design approach.
|
| Strategy for Future Research Activity |
To further understand the effect of initial gap on the occurrence of the vertical residual deformation of the spine frames, finite element analysis of the cyclic loading tests on specimens with post-tensioning strands will be conducted. The finite element models will be firstly verified by the loading test results, then be extended to models with various initial gap distance, damper amounts, and strands amounts.
Time-history analysis of the proposed system with small dampers have been conducted. However, the advantage of energy-dissipation at small vibration stage could not be fully discussed, and some key parameters including the main frame stiffness and input ground motion variety have not been analyzed. Additional time-history analysis will be carried out to complement those discussions and finally clarify the engineering demands of key design components based on the analysis results.
Based on the above studies, evaluation methods and design procedures will be established with clear suggestions for engineering demands of the main structural components of the proposed system. Those methods will be verified simultaneously through time-history analysis.
|
| Causes of Carryover |
One of the main reason for incurring amount is that the two of the three planned conferences were held online and the third one was postponed to the next year. Besides, the amount allocated for the first two years was originally much larger than the last year, so some amount was saved intentionally for the last year in case of additional loading tests and devices for computer simulations.
Extensive numerical analysis will be conducted, which will need some amount for subscribing the finite element analysis software. Besides, some amount is needed for analysis assistants and related data process software as well as computer related devices. The other part of the amount will be used for supporting publication as international journal papers and registration for both domestic and international conferences.
|
