1. Structural Dynamics & Vibration Control Lab 1 Smart Passive System based on MR Damper for Benchmark Structural Control Problem for a Seismically Excited Highway Bridge 4 th World Conference on Structural Control and Monitoring Kang-Min Choi, KAIST, Korea Hyung-Jo Jung, Sejong University, Korea Sang-Won Cho, The University of Western Ontario, Canada In-Won Lee, KAIST, Korea

2. Structural Dynamics & Vibration Control Lab 2 CONTENTS I.Introduction II. Benchmark Highway Bridge Structure III. Smart Passive Control System IV. Numerical Simulation Results V. Conclusions Contents

3. Structural Dynamics & Vibration Control Lab 3 - Viscous fluid out of magnetic field - Solid-like in a magnetic field - Proportional strength to magnitude of magnetism Magnetorheological (MR) fluid Introduction Semiactive MR Dampers Introduction Without Magnetic Fields With Magnetic Fields

4. Structural Dynamics & Vibration Control Lab 4 -Damping coefficient depending on electric current -Requirements : External power for current supply Sensors for feedback control MR fluid damper Introduction Limitation for large-scale structures

5. Structural Dynamics & Vibration Control Lab 5 Introduction Cho, S.W., Jung, H.J., Lee, I.W. (2005) “Smart passive system based on magnetorheological damper.” Smart Materials and Structures, 14, 707-714. - Change characteristics of MR damper with electromagnetic induction (EMI) system - Control without external power and control algorithm - Verified by small-scaled shaking table experiment (Jung et al. 2005) Smart Passive Control System

6. Structural Dynamics & Vibration Control Lab 6 Introduction Investigate the effectiveness of the Smart Passive Control System for Benchmark Structural Control Problem for a Seismically Excited Highway Bridge Objective of this study:

7. Structural Dynamics & Vibration Control Lab 7 91/5 highway bridge in southern California, USA - Details of the bridge are presented in the definition paper (Agrawal et al. 2005) Benchmark Highway Bridge Structure Structural Model Benchmark Highway Bridge Structure Isolated using four non-linear LRB on each abutment and one bearing on each bent column at the center

8. Structural Dynamics & Vibration Control Lab 8 Benchmark Highway Bridge Structure LRB MR damper EMI system Smart Passive System

9. Structural Dynamics & Vibration Control Lab 9 Smart Passive Control System Faster MR damper movement Higher EMF  EMI system is a source of power supply and has adaptability. MR Damper damper deformation magnetic field induced current EMI system Schematic of the Smart Passive System Smart Passive Control System

10. Structural Dynamics & Vibration Control Lab 10 Faraday’s law of electromagnetic induction EMI System for MR Damper Smart Passive Control System : Electromotive force (EMF) N : Number of turns of coil : Magnetic flux B : Magnetic field A : Area of cross section (1)

11. Structural Dynamics & Vibration Control Lab 11 Smart Passive Control System Magnetic Field Solenoid Movement of Solenoid Change of Area (2)

12. Structural Dynamics & Vibration Control Lab 12 Numerical Simulation Results MR damper Numerical Simulation Results Maximum force level: 1000 kN Maximum voltage : 10 Volts - Parameters of the MR damper are described in the sample control design of the benchmark definition paper (Agrawal et al. 2005)

13. Structural Dynamics & Vibration Control Lab 13 Input earthquakes : North Palm Springs (1986) : TCU084 component of Chi-Chi earthquake, Taiwan (1999) : El Centro component of Imperial Valley earthquake (1940) : Rinaldi component of Northridge earthquake (1994) : Bolu component of Duzce, Turkey (1999) : Nishi-Akashi component of Kobe (1995) Numerical Simulation Results

14. Structural Dynamics & Vibration Control Lab 14 Evaluation criteria Numerical Simulation Results J 1 : Pk. base shear J 2 : Pk. over. mom. J 3 : Pk. mid. disp. J 4 : Pk. mid. acc. J 5 : Pk. bear. Def. J 6 : Pk. ductility Peak response quantities Normed response quantities J 9 : Norm. base shear J 10 : Norm. over. mom. J 11 : Norm. mid. disp. J 12 : Norm. mid. acc. J 13 : Norm. bear. Def. J 14 : Norm. ductility

15. Structural Dynamics & Vibration Control Lab 15 Numerical Simulation Results Controller itself J 15 : Pk. control force J 16 : Pk. Stroke J 17 : Pk. instantaneous power J 18 : Pk. total power J 19 : Number of control devices J 20 : Number of sensors J 21 : Dim. of the discrete state vector

16. Structural Dynamics & Vibration Control Lab 16 Optimal passive control Numerical Simulation Results Optimal passive-on (5 V) Voltage (V) Average of sum of evaluation criteria

17. Structural Dynamics & Vibration Control Lab 17 Design of EMI system Numerical Simulation Results Design of EMI system (50V·sec/m) Average of sum of evaluation criteria

18. Structural Dynamics & Vibration Control Lab 18 Numerical Simulation Results - Number of turns of coil - Magnitude of magnetic field - Width of magnets

19. Structural Dynamics & Vibration Control Lab 19 Numerical results Numerical Simulation Results - The effectiveness of the smart passive is clearly demonstrated. Average of each evaluation criteria for all earthquakes

20. Structural Dynamics & Vibration Control Lab 20 Numerical Simulation Results Voltage induced at one EMI system under El Centro earthquake - The enough voltage can be generated by EMI system designed according to structural response. Time (sec) Voltage (V)

21. Structural Dynamics & Vibration Control Lab 21 Numerical Simulation Results - The smart passive system has significant advantage that it requires no power supply during controlling structures with similar function to other control systems - Thus, the smart passive system was able to reduce efficiently by itself without any power supply and control algorithm according to structural responses.

22. Structural Dynamics & Vibration Control Lab 22 - Smart passive control system is based on electromagnetic induction (EMI) using MR damper. - The EMI system takes a role of power supply and has adaptability. Conclusions Conclusions

23. Structural Dynamics & Vibration Control Lab 23 Conclusions Performance verification of benchmark problem - Smart passive system is significantly better than passive -off and -on cases. - Smart passive system is comparable with passive optimal and semiactive Lyapunov control case. : It is highly energy efficient.  Smart passive system is the superior control device.

24. Structural Dynamics & Vibration Control Lab 24 Thank You for Your Attention