Effects of MR Damper Placement on Structure Vibration Parameters

1
Effects of MR Damper Placement on Structure
Vibration Parameters

• By Karla Villarreal
• Advisors
• Claudia Wilson
• Makola M. Abdullah, Ph.D.

2
Overview

• Introduction
• Control Systems
• MR Damper
• Background
• Objective
• Methodology
• Results
• Conclusion
• Future Work

3
Introduction
Parking garage (FEMA 2004) (1)
Collapsed apartment buildings (Kandilli
Observatory and Earthquake Research Institute
1999) (3)
Damage on 12th street (Paso Robles Earthquake
2003) (2)
4
Control Systems

• Systems that absorb vibration or movement
• Passive
• No power required
• Directly damps vibration
• Active
• Requires power
• Applies a force directly into the system to damp
  vibration
• Semi-Active
• Requires minimal power
• Applies a force that changes the system
• Change helps dampen the vibration

5
Magneto-Rheological Damper

• Semi-Active
• Magneto
• Rheology
• Controllable fluid
• Para-magnetic particles

6
Background

• 1940s
• Serviceability
• Suspension systems
• Shock absorbers
• Seat suspensions
• Prosthetics
• Other Uses
• Exercise machines
• Washing machines
• Semi-Active vibration control
• Bridges
• Buildings

LORD Corporation (2004) (5)
7
Research Objective

• To find the effect of MR damper placement on
  the equivalent damping ratio and on the natural
  frequency of a building.

8
Methodology

• MATLAB
• Uncontrolled
• Controlled
• Simulink
• MR damper
• Free vibration response
• Graphical Analysis
• Free Vibration Building Response vs. Time
• Modal Building Response vs. Time
• Data Analysis
• Damping ratio (z)
• Natural frequency shift
• Determine the sensitive current range
• Comparing MR damper placement results

9
Equations

• Equation of Motion of building with earthquake

• Damper Equations (Spencer et al. 1997) (6)

10
MR Damper
11
Controlled and Uncontrolled Systems

• Subjected to FVR
• Constant input of zero force
• Given initial conditions
• 5 cm displacement on each floor

• 3 DOF Building (8)
• Mass 3.456105 kg
• Stiffness 1.2108 kN/m
• 1st natural frequency 1.319 Hz

• 2nd simulation controlled by MR Damper

• 1st simulation uncontrolled

12
Equiv. Damping and Freq. Shift
13
Freq. Response
14
Equivalent Damping Ratios
15
Damper Placement Results
16
Sensitive Current Range
17
Conclusion

• Effect of MR Damper placement on z
• Values decreased as the MR Damper was moved up in
  the building
• Controlled best on 1st Floor
• Effect of MR Damper placement on natural freq.
  shift
• Occurs at every floor
• Larger shifts occur when MR Damper was placed on
  the 1st floor
• Sensitive current range from about 0-3 Amps

18
Future Work

• Comparing the Sensitive Current Range to the
  Sensitive Voltage Range
• Run simulations for
• 10 DOF
• New project on Effects of MR Damper placement on
  bridge vibration response

19
Acknowledgements

• REUJAT
• Dr. Yozo Fujino
• Dr. Shirley J. Dyke
• Tokyo University Grad students
• National Science Foundation
• Makola M. Abdullah, Ph.D.
• Terri Norton, M.S.C.E.
• Claudia Wilson, M.S.C.E.

20
References

• Northridge picture FEMA for Kids
  http//www.app1.fema.gov/cgi-shl/kids/picture.cfm?
  picture002730.gifid10 2004.
• Paso Robles picture Central Coast Tourist
  http//www.centralcoasttourist.com/San_Luis_Obispo
  _CO/earthquake2003/Paso_Robles_Earthquake.htm
  2004.
• Izmit earthquake picture Kandilli Observatory
  and Eartquake Research Institute, Bogaziçi
  University http//www.eas.slu.edu/Earthquake_Cente
  r/TURKEY/ 1999.
• MR Fluid Damper G.Yang."Large-Scale
  Magnetorheological Fluid Damper for Vibration
  Mitigation Modeling, Testing and Control," Ph.D
  dissertation, University of Notre Dame, 2001.
• LORD Corporation, cable stayed bridge
  http//www.lord.com/DesktopDefault.aspx?tabid543
  2004.
• Spencer Jr.,B.F., Dyke, S.J., Sain, M.K.
  Carlson, J.D. (1997). Phenomenological model of
  a magnetorheological damper. J. of Engineering
  Mechanics, ASCE 123(3)230-238.
• Chopra, A.K. (2001). Free Vibration Tests.
  Dynamics of Structures Theory and Applications
  to Earthquake Engineering. 2nd Ed. Prentice Hall,
  Upper Saddle River, NJ54-57.
• Park, K.S., Koh, H.M. Ok, S.Y. (2002). Active
  Control of Earthquake Excited Structures Using
  Fuzzy Supervisory Technique. Advances in
  Engineering Software 33. 761-768.
• Reference the Stiffness stuff
• Ribakov, Y. and Reinhorn, A. M. (2003). "Design
  of Amplified Structural Damping Using Optimal
  Considerations". ASCE Journal of Structural
  Engineering, 129 (10), 1422-1427.