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

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JSSI 10th Anniversary Symposium on

Performance of Response Controlled Buildings

Nov. 17-19 2004, Yokohama Japan

Smart Passive System

Based on MR Damper

Sang-Won Cho : Ph. D, KAIST

Hyung-Jo Jung : Professor, Sejong University

Jong-Heon Lee : Professor, Kyungil University

In-Won Lee : Professor, KAIST


CONTENTS

  • Introduction

  • Electromagnetic Induction System for

    MR Damper

  • Numerical Examples

  • Conclusions

  • Further Study


  • Backgrounds

  • Semi-active control device has

    reliability of passive and adaptability of active system.

  • MR dampers are quite promising semi-active device for

    small power requirement, reliability, and inexpensive to manufacture.


With Magnetic Fields

Without Magnetic Fields

Wires to

Electromgnet

Diaphragm

MR Fluid

Bearing &

Seal

Accumulator

Solenoid


MR damper

  • Requirement of external power, controller, sensors

  • Complication of networks using many MR dampers

    for large-scale structure

  • Difficulties to install and maintain


Development of simple and effective control device

  • Consists of MR damper and EMI system

  • Changes kinetic energy of MR damper to electric energy


  • Schematic diagram

Conventional MR Damper

MR fluid

Line for external power source

Solenoid

MR Damper with EMI System

MR fluid

Solenoid

Permanent magnet

EMI system


Conventional MR Damper

MR Damper

External power

Permanent magnet

MR Damper with EMI System

MR Damper

Solenoid

MR Damper

EMI system


  • Faraday’s law of induction

  • n : turns/m

  • B : magnetic flux

  • B : magnetic field

  • A : cross area

(1)


If we assume as below

- Magnetic field : 1.2 T (Tesla)

- Turns of solenoid : 900 turns/m

- Area of cross section : 13.2 (cm2)

- Velocity of stroke : 9 cm/s

(max. value of uncontrolled)

Area : 13.2cm2

Length : 5cm


  • 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


  • 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

SMART


  • 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

SMART

PASSIVE


  • Three-story building (Dyke et al. 1996)

MR damper



Determination of coil turns for solenoid

By varying two parameters, Sa and Si

Sa : summation of peak acceleration at each floor

Si : summation of peak interstory drift at each floor

which are normalized by uncontrolled responses

Using envelope of maximum value of Sa and Si

for El Centro, Hachinohe, Kobe earthquakes

Two EMI systems are designed:

EMI-A from Sa and EMI-D from Si

  • Design of EMI system


El Centro

El Centro

Kobe

Kobe

Hachinohe

Hachinohe

Max. envelope of Sa

Sa

EMI-A : 2.6104

Coil turns/m

Coil turns/m

Variations of Sa

Envelope of max. responses

Max. envelope of Si

Si

EMI-D : 2.2104

Coil turns/m

Coil turns/m


  • 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


Induced voltages for various earthquakes by EMI system

EL Centro

Hachinohe

Voltage (V)

Kobe

Northridge

Voltage (V)

Time (sec)

Time (sec)


Normalized accelerations at each floor

EL Centro

Hachinohe

Normalized accel.

Clipped-D

Clipped-A

EMI-D

EMI-A

Kobe

Northridge

Normalized accel.

Floor level

Floor level


Normalized interstory drifts at each floor

EL Centro

Hachinohe

Normalized accel.

Clipped-D

Clipped-A

EMI-D

EMI-A

Kobe

Northridge

Normalized accel.

Floor level

Floor level


Normalized peak responses for various earthquakes

Clipped-D

Clipped-A

EMI-D

EMI-A

El Centro

Hachinohe

Kobe

Northridge

Peak Accel.

Peak Drift


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


Korea Patent 0416398

Experimental tests

Numerical modeling of EMI system using neural network

  • Further Study


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