Structural Control: Overview and Fundamentals Akira Nishitani

1. Structural Control: Overview and Fundamentals Akira Nishitani Vice President & ProfessorWASEDA University, Tokyo, Japan anix@waseda.jp

2. Outline 1.Introduction for WASEDA and Myself 2.Introduction for Structural Control 3.Some keywords for structural control 4. Brief view of active structuralcontrol 5.Components of control system 6. Semiactive structural control 7. Smart damping or smart dampers Continued

3. Outline (Cont’d) 8.Significance of nonlinearity or artificially-added nonlinearity in structural control 9.Semiactive variable slip-force level dampers 10. Future directions Appendix LQ control and LQG control

4. ■ 1. Introduction for: Waseda Univ. and myself

5. About Waseda Univ.

6. Waseda University since 1882

7. Waseda University since 1882早稲田大学

8. Waseda University: -Second oldest private university in Japan, founded in 1882. - 125th Anniversary in 2007. - the first private university in Japan that established engineering school. - Waseda Department of Architecture is the second oldest in Japan.

9. Dataof Waseda University: -Number of students: 50,000 - Number of students in School of Science and Engineering: 7,000 - More than 100,000 application forms submitted to the Admission Center every year

11. About myself.

12. Myself: -PhD at Columbia, 1980 - Vice-President, Waseda Univ. since 2006. - Professor of Structural Engineering in Dept. of Architecture, since 1993.

13. Myself (Cont’d): - Have been doing researches related to smart structures technology including active/semiactive structural control for nearly 20 years. - Have been involved to the activity of IASCM[International Association forStructural Control and Monitoring ] since its establishment in 1994.

14. Myself (Cont’d): - Have been the Chairperson of the JSPS[Japan Societyfor Promotion ofScience]157th CommitteeonStructural Response Control since April 2007. - Currently, Vice-President, JAEE[Japan Association of Earthquake Engineering].

15. ■ 2. Introduction for: Structural Control

16. Structural Control: ▲ Active control ▲ Passive control

17. Structural Control: With or withoutEnergy supply With or withoutControl computer ▲ Active control ▲ Passive control

18. Structural Control: With Energy supply With Control computer ▲ Active control ▲ Passive control

19. Structural Control: WithoutEnergy supply WithoutControl computer ▲ Active control ▲ Passive control

20. Structural Control: ▲ Active control - Full-active control - Semi-activeor Semiactive control - Hybridcontrol ▲ Passive control - Base Isolation - Passive damper-based control

21. Structural Control: ▲ The idea of seismic structural control: not a totally new idea. ▲ The basic principles for seismic response control: presented in Japan in 1960.

22. Seismic Response Control Principles: • Reduce the effect of seismic excitation. • 2. Prevent a structure from exhibiting the resonance vibration. • 3. Transfer the vibration energy of a main structure to the secondary oscillator. • 4. Put additional damping effect to a structure. • 5. Add a control force to a structure.

23. These ideas were proposed by Kobori and Minai in 1960.

24. Professor Takuji Kobori

25. They proposed the idea of:Seismic-Response-Controlled Structures or制震構造.

26. Seismic-response-controlled structure Building Nonlinear mechanism Nonlinear mechanism Nonlinear mechanism Nonlinear mechanism

27. Seismic Response Control Principles: • Reduce the effect of seismic excitation. • Base Isolation • 2. Prevent a structure from exhibiting the resonance vibration. • Base Isolation • 3. Transfer the vibration energy of a structure to the secondary oscillator. • TMD Control • 4. Put additional damping effect to a structure. • Passive damper control • 5. Add a control force to a plant. AMD Control

28. Japan has been leading the world in terms of the practical applications of structural control schemes.

29. Practical Applications in Japan: # of Buildings: Base isolation: over 2,000 Passive dampers: over 300 Active control: over 40

30. ■ Keywords for structural control.

31. - TMD- AMD- Smart damper- Semiactive damper- Controllable damper- LQ control- LQG control- Feedback control- Feed-forward control

32. - TMD: Tuned MassDamper- AMD: ActiveMassDamper- Smart damper- Semiactive damper- Controllable damper- LQ control- LQG control- Feedback control- Feed-forward control

33. - TMD: Tuned MassDamper- AMD: ActiveMassDamper- Smart damper- Semiactive damper- Controllable damper- LQ control- LQG control- Feedback control- Feed-forward control

34. There are many kinds of ‘smart’expressionssuch as ‘smart’ cars, ‘smart’ dampers, ‘smart’ structures, ‘smart’ medicine, etc.

35. Indeed, “The Merriam-Webster Paperback Dictionary” gives a modern interpretation of ‘smart.’

36. Containingamicroprocessor of limited calculating capability.

37. With the names such as ‘smart structures,’ ‘intelligent structures,’ ‘dynamic intelligent buildings,’etc., civil structures have been getting more and more human beings-like characteristics.

38. ■ 4. Overview of active structural control:

39. - In 1989, a real building with active control technology applied was completed in Tokyo, Japan. - This was the first full scaleimplementation of active or computer-based response control in the world.

40. Professor Takuji Kobori

41. The name of the building: Kyobashi Seiwa Building (Currently, Kyobashi Center Building)

43. Kyobashi Center Building

44. - This building employed an AMDsystem. -AMD is one of the typical active control devices or actuators for buildings.

45. AMD AMD

46. - AMD is a mass of weight installed into the top floor or near top floor, which is manipulated by a control computer based on the response data.

47. The inertial force resulting from AMD movement responding to Control force Structure Seismic or wind excitation

48. AMD AMD Driving Force Building

49. AMD AMD Driving Forceu Mass of AMD m Building Mass of Building M

50. x AMD xa k X building or main structure K xg