2019 Fiscal Year Annual Research Report
Innovative anti-seismic technology based on magnetorheological materials for building protection
| Project/Area Number |
19F19712
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
中野 政身 東北大学, 未来科学技術共同研究センター, 教授 (40147947)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YANG JIAN 東北大学, 未来科学技術共同研究センター, 外国人特別研究員
|
|---|
| Project Period (FY) |
2019-04-25 – 2021-03-31
|
| Keywords | Variable stiffness / Variable damping / Building protection / Earthquake / Self-powering isolation / Magnetorheology |
|---|
| Outline of Annual Research Achievements |
For the period from April 1st, 2019 to March 31, 2020, my research has made a good progress from the aspects of conducting the proposed project, domestic and international presentations, publications, research awards, and international visits. Specifically, I have completed the proposed research tasks for the first sponsored year including investigating the mechanism and developing controllers of/for the stiffness control as well as the damping control by simulation, completing the design, fabrication, setting up, and initial commissioning of the three stories building system, and designing a dry MR fluid rotary damper with the variable stiffness and damping. I have participated and given presentations in 16th International Conference on Flow Dynamics and the Japan Fluid Power System Society 2019, and given an invited talk in 17th International Conference on Electrorheological Fluids and Magnetorheological Suspensions; from the conferences, I was awarded the “Best Presentation Award for Young Researcher” and the “Best Poster Award”; three papers have been published during this period in Smart Materials and Structures and Mechanical Systems and Signal Processing and one paper was submitted and waiting for the response; and I paid visits to Fuzhou University, China and University of Science and Technology China for research communications in September 2019.
|
| 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 three stories building system with one variable damping and variable stiffness MR damper installed on each floor are simulated, aiming to investigate how the variable stiffness and the variable damping work to reduce the vibrations. The simulation results demonstrated that the variable stiffness can change the natural frequency of the building system, i.e. the greater the stiffness, the greater the natural frequency. Therefore, a point of intersection can be found between two transmissibility which corresponds to two different stiffness. The stiffness controller was then developed using the intersected frequency as the criteria as follow: if the frequency of the earthquake is lower than the intersected frequency, a large stiffness would be chosen, otherwise, a small stiffness would be chosen. In this way, the vibration transmissibility will be guaranteed to be the minimum. The damping controller is based on sky-hook control and the simulation results show that the proposed controllers are effective on reducing the vibrations of the building.
The three stories building system now has been completed in terms of its design, fabrication, setting up, and initial commissioning. It has been set on the shaking table of a vibration excitation system and its natural frequency has been tested, which is 3.5Hz.
The design of the variable stiffness and variable damping dry MR fluid damper has been completed. It is waiting for fabrication. Once the fabrication is completed, testing and characterizations will be conducted.
|
| Strategy for Future Research Activity |
Both static and dynamic testing of newly developed dry MR fluid rotary damper with the variable stiffness and variable damping performances will be conducted to calculate the stiffness of the damper under different loading conditions. A new model will be developed to capture the hysteretic and field sensitive behaviours of the new damper. Suitable control strategies will then be developed to control the damping and the stiffness for the experimental purpose, taking the previous simulation results as importance reference. After the new damper is characterized and modeled, it will be mounted as braces between building floors. Its effectiveness on structural control using a shaking table available in my host's lab in Tohoku University will be evaluated and verified using four benchmark earthquakes that have been widely adopted by the structural control community, namely the 1940 El-Centro, the 1968 Hachinohe, the 1994 Northridge, and the 1995 Kobe earthquake records. Then, the damping and the stiffness of the whole building structure can be controlled by the developed controllers. For the building evaluation system, acceleration performance of each floor and the inter-story drift will be measured as the main evaluation criteria.
International or domestic conferences will be attended for research communication. The relative simulation results and experimental results will be submitted to top journals to be considered for publication.
|
