PPT on TMD.it is a ppt on tuned mass damper.

1. Jalpaiguri Govt. Engg. College
Tuned Mass Damper
By:
SubhajitKumar Biswas
SubhajitGhosh
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2. CONTENTS
• Introduction
• History
• Why to Use TMD
• Design Process of TMD
• General Principle of TMD
• Effect of TMD on Vibrations
• Implementations
• Advantages and Disadvantages of TMD
• Conclusion
• References
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3. INTRODUCTION
 A tuned mass damper (TMD) is a device consisting of
a mass, a spring, and a damper that is attached to a
structure in order to reduce the dynamic response
of the structure. The frequency of the damper is tuned
to a particular structural frequency so that when that
frequency is excited, the damper will resonate out of
phase with the structural motion. Energy is
dissipated by the damper inertia force acting on
the structure
• A tuned mass damper, is preferably placed where the
structure’s deflections are greatest.
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4. HISTORY
 The TMD concept was first applied by Frahm in 1909
(Frahm, 1909) to reduce the rolling motion of ships as
well as ship hull vibrations. A theory for the TMD was
presented later in the paper by Ormondroyd and Den
Hartog (1928),followed by a detailed discussion of optimal
tuning and damping parameters in Den Hartog’s book on
mechanical vibrations (1940). The initial theory was
applicable for an undamped SDOF system.
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5. WHY USE TMD ?
• To reduce the action of earthquake in seismic areas.
• To provide mitigation against wind forces.
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6. Design Process of TMD
• Measure the frequency and magnitude of the undesirable motion
• Develop model of existing structure and determine the TMD mass and
placement of TMD(s) to achieve vibration mitigation requirement
• Perform prototype testing of the TMD to fine-tune the design
• Measure the motion of the TMD(s) on the structure to confirm
performance and that the mitigation objective was achieved
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7. Types of TMD
Based on Control Mechanism :
Active Mass Damper Passive Mass Damper
An active control system is one in which an
external power source the control actuators
are used that apply forces to the structure
in a prescribed manner. These forces can be
used to dissipate energy from the structure.
In an active feedback control system, the
signals sent to the control actuators are a
function of the response of the system
measured with physical sensors
A passive control system does not require
an external power source. Passive control
devices impart forces that are developed in
response to the motion of the structure.
Total energy (structure plus passive device)
cannot increase, hence inherently stable.
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8. General Principle of TMD
•The damper consists of a
mass M2, of a spring K2 and of
a damping C2
• The value of M2 and K2 are
chosen so that the moving
part of the damper system can
be tuned properly to the
structure frequency.
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9. Effect of TMD on
Vibrations
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10. Effect of TMD on
Vibrations
 decay curve of structure with
no damper
 decay curve of structure with
a damper
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11. Implementations
Tuned mass dampers are mainly used in the following applications:
• Tall and slender free-standing structures (Skyscrapers, bridges,
chimneys, TV towers)
• Tall and slender free-standing structures (Skyscrapers, bridges,
chimneys, TV towers)
• Bidges and pedestrian bridges
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12. TMD for Skyscraper
 Largest Tuned Massed Damper (TMD) in the world-730 tons and
5.5 m diameter
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13. TMD on different
structures
IN BRIDGES IN STADIUM
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14. Other Skyscrapers with TMD’s
• Citicrop Centre, New York
• John Hancock Tower, Boston
• CN Tower, Toronto
• Chiba Port Tower, Japan
• The worlds largest building in present the BURZ KHALIFA
is equipped with 11 different TMD’S to to control the
vibrations.
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15. Advantages &
Disadvantages
Advantages Disadvantages
 They do not depend on an
external power source for their
operation.
 They can respond to small level
of excitation.
 Their properties can be adjusted
in the field.
 They can also be introduced in
upgrading structure.
 They require low maintenance.
 They can be cost effective.
 A large mass or a large space
is needed for their
installation.
 The effectiveness of a tuned
mass damper is constrained
by the maximum weight that
can be practically placed on
top of the structure
 Their effectiveness depends
on the accuracy of their
tuning, but natural
frequencies of a structure
cannot be predicted with
great accuracy.
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16. CONCLUSIONS
As we conclude it is very much evident that with certain
drawbacks, TMDs are very effective tool to protect the
structures from various lateral forces ,like wind forces,
earthquake effects, and thereby it can save our property
and priceless lives.
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17. REFERENCES
 Structural dynamics,Mario Paz
 www.wikipedia.org
 www.engineeringcivil.org
 www.theconstructor.org
 www.GERB.com
 www.csaengineering.com
 www.civilumd.edu
 www.youtube.com etc.
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18. YOU
THANK
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