This is introduction for vibration control systems

1. Proposing suitable vibration control methodsfor excessive lateral vibration of
different kind tall structures
SUPERVICER
DR.J.A.S.C.JAYASINGHE
K.SUJEEVAN

2. PRESENTATION OUTLINES
Passive control system
Tuned mass damper
Pounding tuned mass
damper
Next step
Conclusion
Reference

3. Propose suitable vibration control methods for excessive
lateral vibration of different kind tall structures with
considering of economic , operation and maintenance
AIM

4. SCOPE
•Study passive control system
•Study active control system
•Study semi active control system
•Modelling and analysinga high-rise structure using
SAP2000
•Comparing the results
•Proposed suitable method

5. PASSIVE CONTROL SYSYTEM
In this case, the passive devices does not need an external power, this
kind of method has some features such as, (Tuned Mass Damper, Viscous
Damper), It’s against minor wind excitation and minor earthquakes.
No need for external energy
Stable
Simple process and operation

6. It is a passive device which utilizes a secondary mass attached to a
main structure through spring and dashpot.
Advantages
-> Their simplicity
->
Efficiency Draw
back
-> Ineffectiveness during strong earthquakes. Because of the
limitation in the installation space in real engineering
structures,
TUNED MASS DAMPER

7. The equation of motion of the TMD system
𝑚2ẍ2 + 𝑐2(ẋ2 − ẋ1) + 𝑘2(𝑥2 − 𝑥1) = 0
Combined of motion
𝑚1ẍ1 + 𝑐1(ẋ1) + 𝑐2(ẋ1 − ẋ2) + 𝑘1(𝑥1) + 𝑘2(𝑥1 − 𝑥2) = 𝑓
the attached TMD increases the damping and stiffness of the
combined system and reduces the vibration.
TUNED MASS DAMPER

8. Factors affecting this
TMD
Mass ratio
Frequency ratio
Optimum damping
ratio
TUNED MASS DAMPER

9.  Mass ratio
μ = 𝑚�
𝑀
𝑚�= absorber mass
𝑀= generalized mass of primary structure
Normalized response =
response with TMD
response without TMD
TUNED MASS DAMPER

10.  Tuning frequency ratio
𝑓‫݀𝑚ݐ‬
𝑓‫ݏ‬
 𝑓‫݀𝑚ݐ‬ = natural frequency of TMD and
 𝑓‫ݏ‬ = natural frequency of the generalized primary
structure
TUNED MASS DAMPER

11. Damping ratio
 Performance of TMD in vibration mitigation is quite sensitive to
the damping ratio of the TMD.
 TMD splits the natural frequency of primary structure into a lower
and
higher frequency.
 If the damping is too low, then resonance occurs at the two
undamped
resonant frequencies of the combined system
 If the damping is too large, the mass block may be locked and the
TMD may lose the ability to absorb energy.
TUNED MASS DAMPER

12. 𝜉�� ‫=ݐ‬ √(3𝜇/ 8(1+𝜇))
Where μ is the mass ratio
 friction dampers
 MR dampers
TUNED MASS DAMPER

13.  In recent years Pounding TMD has gained popularity over
conventional
TMD in reducing the accelerations produced by seismic activity.
 for reducing earthquake effects in power transmission towers
POUNDING TUNED MASS DAMPER

14. the vibration amplitude of the structure is reduced by transferring
momentum between structure and added mass of the PTMD. Then
the absorbed mechanical energy is dissipated as heat energy
POUNDING TUNED MASS DAMPER

15. CONCLUSION
 The TMD has no significant effect in reducing the absolute acceleration,
base shear force, and the overall turning moment of the building.
 When the TMD was replaced by a PTMD, under earthquake loads, there
was no significant reduction in the maximum displacement at the top
floor, but there was maximum the reduction in the top floor acceleration,
 there was no significant change in the standard deviation of acceleration
at the top floor.

16.  Study about active and semi active control
systems
 Modeling a high-rise building using SAP2000
 Analyze the structure using these cases
 Comparing results
 Choose best control system
NEXT

17.  Abburu, S. (2015), “On the Design of High-Rise Buildings for Multihazard:
Fundamental Differences between Wind and Earthquake Demand,” Shock
and Vibration, 2015, Article ID 148681.
 A.M., (2015), “Control of wind-induced motion in high-rise buildings with hybrid
TM/MR dampers”, Wind and Structures, 21(5), 565-595.
 A.M. (2014a), “Proposed robust tuned mass damper for response mitigation in
buildings exposed to multidirectional wind,” The Structural Design of Tall and
Special Buildings 23(9), 664-691.
REFERENCE

18. Thank you