1. Smart Passive System Based on MR Damper JSSI 10 th Anniversary Symposium on Performance of Response Controlled Buildings Nov. 17-19 2004, Yokohama Japan Sang-Won Cho: Ph. D, KAIST Hyung-Jo Jung: Professor, Sejong University Jong-Heon Lee : Professor, Kyungil University In-Won Lee: Professor, KAIST Sang-Won Cho: Ph. D, KAIST Hyung-Jo Jung: Professor, Sejong University Jong-Heon Lee : Professor, Kyungil University In-Won Lee: Professor, KAIST

2. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 1 CONTENTS Introduction Introduction Electromagnetic Induction System for Electromagnetic Induction System for MR Damper MR Damper Numerical Examples Numerical Examples Conclusions Conclusions Further Study Further Study

3. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 2 Backgrounds Backgrounds Introduction Introduction Semi-active control device hasSemi-active control device has reliability of passive and adaptability of active system. MR dampers are quite promising semi-active device forMR dampers are quite promising semi-active device for small power requirement, reliability, and inexpensive to manufacture.

4. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 3 Without Magnetic Fields With Magnetic Fields Bearing & Seal Solenoid Accumulator MR Fluid Diaphragm Wires to Electromgnet Characteristics of Magnetorheological (MR) fluid Characteristics of Magnetorheological (MR) fluid and damper and damper

5. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 4 Installation of Conventional MR Damper Installation of Conventional MR Damper MR damper Requirement of external power, controller, sensorsRequirement of external power, controller, sensors Complication of networks using many MR dampersComplication of networks using many MR dampers for large-scale structure Difficulties to install and maintainDifficulties to install and maintain

6. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 5 Objective and Scope Objective and Scope Development of simple and effective control device Consists of MR damper and EMI systemConsists of MR damper and EMI system Changes kinetic energy of MR damper to electric energyChanges kinetic energy of MR damper to electric energy

7. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 6 Schematic diagram Electromagnetic Induction (EMI) System EMI system Line for external power source MR fluid Solenoid MR fluid Solenoid Permanent magnet Conventional MR Damper MR Damper with EMI System

8. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 7 Mechanism MR Damper Permanent magnet Solenoid External power Conventional MR Damper MR Damper with EMI System EMI system

9. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 8 Faraday’s law of induction n: turns/m  B : magnetic flux B: magnetic field A: cross area (1) Estimation of induced voltages by EMI system

10. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 9 If we assume as below - Magnetic field: 1.2 T (Tesla) - Turns of solenoid : 900 turns/m - Area of cross section: 13.2 (cm 2 ) - Velocity of stroke: 9 cm/s (max. value of uncontrolled) Length : 5cm Area : 13.2cm 2

11. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 10 Adaptability: damping varies with strength of external loads Simplicity: No power, no controller, and no sensors Thus, we propose smart passive system based-on MR damper Efficiency: ?? EMI system will be applied to numerical example for examination of efficiency and applicability Advantages of MR damper with EMI system

12. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 11 Adaptability: damping varies with strength of external loads Simplicity: No power, no controller, and no sensors Thus, we propose smart passive system based-on MR damper Efficiency: ?? EMI system will be applied to numerical example for examination of efficiency and applicability Advantages of MR damper with EMI system SMART

13. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 12 Adaptability: damping varies with strength of external loads Simplicity: No power, no controller, and no sensors Thus, we propose smart passive system based-on MR damper Efficiency: ?? EMI system will be applied to numerical example for examination of efficiency and applicability Advantages of MR damper with EMI system SMART PASSIVE

14. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 13 Three-story building (Dyke et al. 1996) Numerical Example MR damper

15. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 14 System data

16. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 15 Determination of coil turns for solenoid By varying two parameters, S a and S i S a : summation of peak acceleration at each floor S i : summation of peak interstory drift at each floor which are normalized by uncontrolled responses Using envelope of maximum value of S a and S i for El Centro, Hachinohe, Kobe earthquakes Two EMI systems are designed: EMI-A from S a and EMI-D from S i Design of EMI system

17. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 16 Variations of S a Envelope of max. responses Coil turns/m SaSa Hachinohe Kobe El Centro Coil turns/m SiSi Hachinohe Kobe El Centro EMI-A : 2.6  10 4 EMI-D : 2.2  10 4 Max. envelope of S a Max. envelope of S i

18. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 17 Comparisons – Proposed EMI systems : EMI-A, EMI-D – Conventional MR damper : Clipped-A, Clipped-D （ using clipped-optimal controller) Performances – Normalized acceleration and drift at each floor – El Centro, Hachinhe, Kobe, Northridge earthquakes Analysis

19. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 18 Induced voltages for various earthquakes by EMI system Time (sec) Voltage (V) Time (sec) EL Centro Kobe Hachinohe Northridge Results

20. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 19 Normalized accelerations at each floor EL Centro Kobe Hachinohe Northridge Floor level Normalized accel. Floor level Clipped-D Clipped-A EMI-D EMI-A

21. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 20 Normalized accel. EL Centro Kobe Hachinohe Northridge Floor level Clipped-D Clipped-A EMI-D EMI-A Normalized interstory drifts at each floor

22. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 21 Normalized peak responses for various earthquakes El Centro Hachinohe Kobe Northridge Peak Accel.Peak Drift Clipped-D Clipped-A EMI-D EMI-A

23. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 22 Smart Passive System Developed Consists of MR damper and EMI system Adaptable to external loads Simple structure without power, controller, sensors Shows comparable performances to clipped optimal controller Conclusions Conclusions

24. Structural Dynamics & Vibration Control Lab., KAIST, Korea Structural Dynamics & Vibration Control Lab., KAIST, Korea 23 Korea Patent 0416398 Experimental tests Numerical modeling of EMI system using neural network Further Study Further Study