1. Structural Dynamics & Vibration Control Lab.
토목환경공학개론:
Overview of vibration control
건설·환경공학과
구조동역학 및 진동제어 연구실
Structural Dynamics & Vibration Control Lab.

2. 목차 1. Introduction 1.1 Background
1.2 Recent international developments
1.3 Scope
1.4 Definitions
2. Passive energy dissipation
2.1 Metal yield dampers
2.2 Friction dampers
2.3 Viscoelastic dampers
2.4 Viscous fluid dampers
2.4 Tuned mass dampers
2.5 Tuned liquid dampers
2.6 Other energy dissipators
2.7 Code development and concluding remarks

3. 1. Introduction 1.1 Background Motive
Evolution of structural control in the u.s
Evolution of structural control in the world
Distinctive features of structural control

4. Motive Increased flexibility
The trend toward taller, longer and more flexible structures
Increased safety levels
Higher safety level demands : tall structures, nuclear power plants
Increased stringent performance requirements
Strict performance guide lines : radar tracking stations, radio telescope structures, aerospace structures
Better utilization of materials and lower cost
Economic considerations : savings in materials, weight and costs

5. Evolution of structural control in the U.S
Roots primarily in the aerospace-related problems
Tracking, pointing, flexible space structure
The protection of buildings and bridges
For extreme loads of earthquakes and wind
Conceptual study by Yao in 1972
Open loop control, closed loop contol, feedback structural control
The first world conference on structural control in 1994

6. International association for structural control in 1994
Evolution of structural control in the U.S
International association for structural control in 1994
ASCE became a member of Amerian Automatic Control Council(AACC) in 1995.
Passive base isolation system become an accepted design strategy.

7. Open & closed loop control
Yao’s concept of structural control
Feed back control
Open & closed loop control

8. Evolution of structural control in the world
More than 100 years ago.
Wood house placed on ball bearings (Jone Milne, P.F. of engineering in Japan)
1950’s
Linear system theory application to the structural dynamics
Developed from internal combustion engine
1960’s
Base isolation for low-rise and medium-rise structures and bridges
Characteristics of base isolation
Filters high frequencies of the ground acceleration
Lengthens the natural period of vibration to about 2s
Induces large amplitude motion

9. 1972 ~ Active structural control (concepts form Yao 1972)
Evolution of structural control in the world
1972 ~
Active structural control (concepts form Yao 1972)
Hybrid structural control
Semiactive structural control

10. Distinctive features of structural control
Civil engineering structures are statically stable
The addition of purely active control force can cause destabilization
In contrast to aerospace structures which requires active control for stability
Loads are highly uncertain
Earthquake and wind loads have no definite magnitude and arrival time.
Mechanical loads are fairly well documented.
Erformance requirements are generally coarse

11. 1.2 Recent International Developments
The U.S. National Workshop on Structural Control
The Japan National Workshop on Structural Control
The U.S.- Italy Workshop on Structural Control
The Tenth World Conference Conference on Earthquake
Engineering in Madrid, Spain
International Workshop on Structural Control in Hawaii
The Formation of IASC
International Association for Structural Control
First European Conference on Structural Control
The Second IASC in Hong Kong
The Third IASC in Tokyo

12. 1.3 Scope The current state of the art in the control and monitoring
Of civil engineering structures
A link between structural control and other fields of control theory
Future research needs and application efforts.

13. 1.4 Defintions Active control Passive control
1.4 Definitions
1.4 Defintions
Active control
External source powers control actuators
Actuators apply forces to the structure in a prescribed manner.
These forces can be used to both add and dissipate energy.
Type : open-loop control, closed-loop control
Passive control
Does not require an external power source.
Impart forces that are developed in response to the motion of the structure.
The energy in the passively controlled system can not be increased.

14. 1.4 Definitions - active control ex 1)
Location : Kao Hsiung, Taiwan
Size : 150m x 60m at Base, 85-story
Fuction of building : Multi-purpose
Control system : Multi-staged tuned active damper

15. 1.4 Definitions - passive contol ex 1)

16. 1.4 Definitions - passive contol ex 2)

17. 1.4 Definitions - passive contol ex 3)

18. 1.4 Definitions - passive contol ex 4)

19. 1.4 Definitions - passive contol ex 5)

20. Hybrid control Semiactive control
1.4 Definitions
Hybrid control
The combined use of active and control systems
Ex 1) viscoelastic damping + active mass damper
Ex 2) base isolation + actuator
Semiactive control
External energy requirements are smaller than active control system.
Do not add mechanical energy to the structural system.
Often viewed as controllable passive devices.

21. 1.4 Definitions - hybrid control ex 1)

22. 1.4 Definitions - hybrid control ex 1)

23. 1.4 Definitions - semi active control ex 1)

24. Structural health monitoring
1.4 Definitions
Structural health monitoring
Detect changes that may include damage or degradation.
In-situ, nondestructive sensing and analysis of structural characteristics including structural response.

25. 2. Passive energy dissipation
All vibrating structures dissipate energy
Due to internal stressing, rubbing, cracking, plastic deformation, and so on
Methods of increasing the energy dissipation capacity are very effective in reducing the amplitudes of vibration.
This may achieved by conversion of kinetic energy to heat, or by transferring of energy among vibrating modes.

26. Conversion of kinetic energy to heat
Devices that operate on principles such as frictional sliding, yielding of metal, phase transformation in metal.
Transferring of energy among vibrating modes
Supplemental oscillators, which act as dynamic vibration absorbers

27. 2.1 Metallic yield dampers
Inelastic deformation of metals.
Very effective for the dissipation of energy input structure from an earthquake
The idea of utilizing added metallic energy dissipators (kelly, 1972; Skinner, 1975)
Many devices use mild steel plates with triangular or hourglass shapes so that yielding is spread almost uniformly throughout the material.

28. ADAS : A typical X-shaped plate damper or added damping and stiffness
Metallic yield dampers
ADAS : A typical X-shaped plate damper or added damping and stiffness

29. Metallic yield dampers
The area within the hysteresis loops measures the amount of dissipated energy.

30. Some particularly desirable features of these devices
Metallic yield dampers
Other materials, such as lead and shaped-memory alloys, have been evaluated. (Sakurai, 1992; Aiken and kelly, 1992)
Some particularly desirable features of these devices
Stable hysteretic behavior, low-cycle fatigue property, long-term reliability, relative insensitive to environmental temperature
An inelastic constitutive model for the material of metallic yield dampers is developed. (Dargush and soong, 1995)
A finite-element formulation for the tapered-plate energy dissipator is developed. (Tsai, 1995)

31. Metallic yield dampers

32. Metallic yield dampers

33. The direct use of experimental data
Metallic yield dampers
The result shows that the proposed model effectively predicts the device behavior under wind and earthquake loading.
The direct use of experimental data
The hysteretic model is first selected.
The model parameters are determined.
The relationships between the model parameters and the size and material parameters of the device are established.
By employing a bilinear model, the relationships between the model parameters and the size and material parameters are established. (Ou and Wu, 1995)

34. Utilize metallic dampers within a structural system
Metallic yield dampers
Utilize metallic dampers within a structural system
Formulate design guidelines and procedures based on knowledge gained from theoretical and experimental study.
Key parameters in reducing seismic response
B/d (ratio of bracing stiffness to device stiffness)
SR (brace-device assemblage stiffness to that of corresponding structural story)
(Yielding displacement of the device)
(Xia, 1990; Xia and hanson,1992; Tsai, 1993; Pong, 1994)

35. Metallic yield dampers
Applications
The earliest applications of metallic dampers to the structural systems occurred in New Zealand. (Skinner, 1980)
ADAS devices have been installed in a 29-story steel-frame building in Nalpes, Italy. (Ciampi, 1991)
In a two-story nonductile reinforced concrete building in San Francisco as a part of seismic retrofit. (Perry, 1993)
In three reinforced concrete buildings in Mexico City as a part of seismic retrofit. (Martinez-Romero, 1993)
In Japan, lead extrusion devices and metallic yield dampers have been installed in a number of buildings.

36. Friction dampers
2.2 Friction dampers
Friction provides another excellent mechanism for energy dissipation.
It is important to minimize stick-slip phenomena to avoid introducing high-frequency excitation.
Compatible materials must be employed to maintain a consistent coefficient of friction over the intended life of device.

37. Friction dampers

38. Friction dampers

39. The dampers are not to slip during wind storms or moderate earthquake.
Friction dampers
The dampers are not to slip during wind storms or moderate earthquake.
However, under severe loading conditions, the devices slip before yielding occurs in primary structural member.
These device not significantly affected by loading amplitude, frequency, the number of loading cycles.

40. Composition of the interface
Friction dampers
Composition of the interface
Steel to steel, brass to steel, graphite impregnated bronze on stainness steel
Great importance for insuring longevity of operation of the devices
Most friction dampers used coulomb friction with a constant coefficient of friction.
Key parameters in reducing seismic response
YSR (ratio of initial slip load to yielding force of corresponding structural story)
SR (ratio of bracing stiffness to stiffness of corresponding structural story)
(Nims, 1993; Scholl, 1993)

41. A combination mechanism
Friction dampers
A combination mechanism
A friction damping device for control of structural damage due to severe earthquake motion
A viscoelastic damping device for control of low energy excitation
(Tsiatas and Olson,1998; Pong, 1994a,b; Tsiatas and Daly, 1994)
A bidirectional friction device
Consist of stack of sliders that are alternately flat and convex
Provide a nearly circular distribution of clamping pressure over the contact area
(Dorka, 1992)

42. Applications Pall friction devices have been installed in canada
Metallic yield dampers
Applications
Pall friction devices have been installed in canada
Sumitomo friction dampers have been installed in a 31-story steel-frame sonic office building in japan. (Aiken and kelly, 1990)
Pall x-braced friction devices and their variations have been installed in several buildings as a retrofit and new facility.
(Pall, 1993,1996)

43. 2.3 Viscoelastic dampers(vd)
1. Viscoelastic materials
① Characteristic
1) Rate dependent behavior (viscous)
2) Elastic behavior (elastic)
3) Store and dissipate energy at all deformation levels
② Kind
1) Polymeric materials :
<fig Typical polymeric structure network>
2) Glassy materials :
<fig Typical glass structure (sodium-silicate glass)>
③ Application : both wind and seismic protection

44. Viscoelastic dampers
2. Typical viscoelastic damper (by the 3M company inc.) by shen and soong(1995)
<Fig Viscoelastic damper > < fig Typical hesteretic loops >
▶ Viscoelastic dampers dissipate enegy through shear deformation of
the viscoelastic layers

45. 3. Basic principles (Zhang et al,1989)
Viscoelastic dampers
3. Basic principles (Zhang et al,1989)
: Shear strain : Loss factor
: shear stress
: Shear storage modulus
: Shear loss modulus
Under a sinusoidal load with frequency 
→ ,
→ where ,
Using
→ (1)
▶ First term : in-phase portion with representing the elastic modulus
Second term : out-of-phase portion represents the energy dissipation component
▶ , : Analytical expressions obtained
Using experimental results (Chang et al,1993)
Using the Boltzmann’s superposition principles(Shen and Shoon,1995)

46. 4. Characteristics ① Force-displacement relationship
Viscoelastic dampers
4. Characteristics
① Force-displacement relationship
(2)
Where
A : Total shear area ,  : Total thickness
▶ A linear structural system with added viscoelastic dampers
remains linear with the dampers
→ A significant simplification in analysis of viscoelastically damped systems
(Zhang et al.1989 ; Zhang and Soong.1992)
② Response analysis for linear system
▶ SDOF : Using eqs. (1) and (2)
▶ MDOF : Using the modal strain energy method (← Finite element analysis)
(Soong and Lai.1991 , Chang et al.1993)

47. ③ Temperature effect on the behavior of viscoelastic materials
Viscoelastic dampers
③ Temperature effect on the behavior of viscoelastic materials
→ Investigated and quantified (Chang et al.1992 ; Shen and Soong.1995)
→ Natural period varies moderately under varying temperatures
→ If the damper is designed as a stiff device,
the damping ratio is almost unchanged when the temperature changes
( Kasai et al.1994)
→ If the temperature is constant,
the viscoelastic material is linear over a wide range of strain
→ At large strains :
considerable self-heating due to the large amount of energy dissipated ↓
change the mechanical properties of material
the overall behavior is nonlinear
→ Heating-softening effect is present even linear response
: linear analysis can only be for approximation of the response
the frequency domain approach is not suitable for seismic applications
when large strains are most likely experienced

48. 5. Research development ① Makris(1994)
Viscoelastic dampers
5. Research development
① Makris(1994)
→ Present a complex-parameter Kelvin model
→ Parameters are complex-valued but frequency-independent
Applicable for nonlinear systems
② Makris and Dargush(1994)
→ Present a boundary-element formulation for the dynamic analysis
of generalized viscoelastic materials
③ Blondet(1993)
→ Two full-scale dampers were dynamically tested
④ Nielsen(1994)
→ Six smaller dampers were tested to failure
: The failure occurred at very large strain levels

49. → Full-scale prototype structure incorporated with VD was tested
Viscoelastic dampers
⑤ Chang(1993), Lai(1995)
→ Full-scale prototype structure incorporated with VD was tested
⑥ Chang(1994)
→ Experimental and analytical studies on the inelastic seismic behavior
of two 2/5-scale steel movement restoring frames with and without VD
⑦ Recent experimental and analytical studies
( Foutch(1993) ; Lobo(1993) ; Chang(1994,1995) ; Shen(1995))
→ Apply to steel as well as reinforced concrete structures
under a wide range of intensities of earthquakes
▶ Note : steel structure → seismic response is elastic
reinforced concrete structure → seismic response is inelastic ↓
permanent deformation and damage
addition of VD can reduce the development of damage

50. 6. Application to civil engineering structures
Viscoelastic dampers
6. Application to civil engineering structures
① World Trade Center in New York (1969)
(a) The World Trade Center (b) Damper installation
<Fig Damper installation in the World Trade Center, New York>
( Courtesy of the 3M Company, St.Paul,MN )
→ 10,000 VDs in each tower (distributed from 10th to 110th floor)

51. ② The Columbia SeaFirst Building in Seattle (1982)
Viscoelastic dampers
② The Columbia SeaFirst Building in Seattle (1982)
(a) The Columbia SeaFirst Building (b) Damper installation
<Fig Damper installation in the Columbia SeaFirst Building,Seattle>
(Courtesy of the 3M Company,St.Paul,MN)
→ 260 VDs
→ To reduce wind-induced vibration

52. ③ The Two Union Square Building in Seattle (1988)
Viscoelastic dampers
③ The Two Union Square Building in Seattle (1988)
(a) The Two Union Square Building (b) Damper installation
<Fig Damper Installation in the Two Union Square Building, Seattle>
(Courtesy of the 3M Company, St.Paul,MN)
→ 16 large VDs were installed parallel to four columns in one floor
→ To reduce wind-induced vibration

53. ④ The 13-story steel frame Santa Clara Country Building
Viscoelastic dampers
④ The 13-story steel frame Santa Clara Country Building
in San Jose,Calif (1994)
→ Use viscoelastic dampers to reduce seismic response
⑤ The Chien-Tan railroad station roof in Taipei,Taiwan (1994)
→ Utilized the dampers to reduce wind-induced vibrations
⑥ A navy-owned three-story lightly reinforced concrete building
in San Diego (1997)

54. 2.4 viscous fluid dampers (VFD)
1. Fluids can be used to dissipate energy
2. Application scopes of VFD : arerospace
Military applications
Structural application
3. Characteristic : ① Linear viscous response over a broad frequency range
② Insensitivity to temperature
③ Compactness in comparison to stroke and output force
▶Study of the seismic retrofit of reinforced concrete structures (reinhorn,1995)
→ Results : reduce inelastic deformation demand
Reduce damage quantified by an index monitoring permanent deformation

55. Viscous fluid dampers
4. Several kinds of VFD
① Cylindrical pot fluid dampers
<Fig Cylindrical pot GERB damper >
( Makris and Constantinou, 1991)
② Viscous damping walls
<Fig Viscous damping wall >
(Miyazaki and Mitsusaka, 1992)
③ Orificed fluid dampers
<Fig Schematic of fluidic orfice design>
(Constantinou and Symans, 1993)

56. Viscous fluid dampers
5. Typical damper
<Fig Taylor devices fluid damper (Constantinou et al.1993) >
▶ It dissipates energy through movement of the piston in the highly viscous fluid
▶ Over a large frequency range ⇒ viscoelastic fluid behavior
▶ For Newtonian fluid (purely viscous fluid)
⇒ The output force is proportional to velocity of the piston

57. 6. General Maxwell model (Makris and Constrantinou)
Viscous fluid dampers
6. General Maxwell model (Makris and Constrantinou)
X : Displacement of the piston
F : Output force
: Material constant ← Obtained through damper tests
(Constantinou and Symans , 1992)
: Fractional derivative
▶ For r=q=1 → Maxwell Model
( : Relaxation time, : Damping constant )
▶ For model of the damper below the cut-off frequency about 4Hz →

58. ▶ Most VFDs in current applications →
Viscous fluid dampers
▶ Most VFDs in current applications →
• Obtained by special design of the orifices
• Advantages : the force tends to flatten out at higher velocities
7. Application of VFDs to civil engineering structures
① Two residential buildings in Los Angeles (Huffmann,1985)
→ Isolation systems with helical steel springs and viscous dampers
→ Earthquake protection
<Fig Base isolation system with helical springs
and cylindrical pot fluid dampers (Huffmann, 1985)>

59. ② 1-km bridge weighing 25,000 tons in Italy (1991)
Viscous fluid dampers
② 1-km bridge weighing 25,000 tons in Italy (1991)
→ Protected by viscous silicon gel dampers at each abutment
( weigh : 2ton , length : 2m , stroke : 500mm )
③ 78.6m high, 14-story building at the center of Shizouka City, Japan
→ Viscous walls have been used
<Fig SUT-Building in Shizuka city,Japan> < Fig VDW locations in SUT-Building>
(Courtesy of Sumitomo Construction Co.,Ltd.,Tokyo,Japan) ( Miyazaki and Mitsusaka,1992)

60. ④ Five buildings of the new San Bernardino Medical Center (1994)
Viscous fluid dampers
④ Five buildings of the new San Bernardino Medical Center (1994)
→ base isolation system with viscous fluid dampers
→ 233 dampers
( each damper : output force = 320,000 lbs
energy dissipation level = 3,000 HP (at 60 in/s) )
⑤ Boiler frame in Japan (1994)
→ results : seismic displacement response of the boiler frame with dampers
is reduced to 50-60% of the response without the dampers
⑥ 3-Story Pacific Bell North Area Operations Center (1995)
→ 62 Dampers ( each damper : capacity = 130kN , stroke=50mm)
(a) Under construction (b) Damper installation
<Fig Pacific Bell North Area Operations Center>
(Courtesy of Taylor Devices, Inc.,N.Tonawanda,NY)

61. 2.5 Tuned mass dampers (TMD)
1. Basic principle
<Fig Models of SDOF structure and TMD>
Total effective damping ceq =
We can reduce the response of structure system by adding tmd

62. 2. Practical considerations
Tuned mass dampers
2. Practical considerations
① The amount of added mass
② TMD travel relative to the structure
③ Sensitivity to low levels of excitation
3. Research development
▶ As of today, most TMD applications have been made toward mitigation
of wind-induced motion
▶ The seismic effectiveness of TMDs remains an important issue
① Den Hartog (1947)
→ Secondary mass with tuned spring and damping elements
→ Increase damping in the primary structure
② Clark (1988)
→ Propose the concept of MTMDs together with an optimization procedure
Note : MTMD is to overcome the frequency-related limitations of TMDs

63. ③ Xu and Igusa (1992) ; Yamaguchi and Harnpornchai (1993)
Tuned mass dampers
③ Xu and Igusa (1992) ; Yamaguchi and Harnpornchai (1993)
→ Study on the behavior of MTMDs connected in parallel to the main system
④ Setareh (1994)
→ Propose DTMD consisting of two masses connected
in series to the structure
→ Analytical Results
▶ DTMDs are more efficient than the conventional single mass TMDs
over the whole range of total mass ratios
▶ DTMDs are only slightly more efficient than TMDs
over the practical range of mass ratio ( )
⑤ Matsuhisa et al (1994)
→ Compare the effectiveness of TMDs of the spring-mass type
the pendulum type
the circular track type
→ Optimal TMD configurations is quite different

64. → Studied the effectiveness of a ring-type pendulum TMD
Tuned mass dampers
⑥ Li et al (1994)
→ Studied the effectiveness of a ring-type pendulum TMD
on reducing seismic response of tall chimneys
⑦ Villaverde (1994)
Numerical and experimental results on reducing the response of structure
during different earthquakes
→ Some cases give good performance
→ Some have little or even no effect
→ Dependency on the characteristics of ground motion
▶ Response reduction is large for resonant ground motion
▶ Response reduction diminishes as the dominent frequency of the ground
motion get futher away from the structure’s natural frequency

65. 4. Application to civil engineering structure
Tuned mass dampers
4. Application to civil engineering structure
① The Centerpoint Tower in Sydney, Australia
(ENR, 1971 ; Kwok and MacDonald, 1987)
(a) Centerpoint Tower (b) Water Tank TMD
<Fig TMD in Centepoint Tower (Kwok and MacDonald,1987)>

66. ② Citicorp Center in New York and John Hancock Tower in Boston
Tuned mass dampers
② Citicorp Center in New York and John Hancock Tower in Boston
(a) Citicorp Center (b) TMD in Citicorp Center (Petersen,1980;1981)
<Fig TMD in Citicorp Center>

67. 2.6 Tuned liquid dampers ( TLD )
Viscous action of fluid and wave breaking
Liquid sloshing

69. TLCD Tube filled with water Passage of liquid through an orfice
2.6 Tuned liquid dampers
TLCD
Tube filled with water
Passage of liquid through an orfice
Fundamental frequency  Length of column of water
Dissipation term  Nonlinear & depend on head loss

70. TMD TLD No activation mechanism Maintenance cost  All time active
Problem of inadequate setting
TLD
No activation mechanism
Maintenance cost 
All time active
The involved theory  Complicated
Hardware requirement & installation  Simple
At larger amplitude
 Not sensitive to actual frequency ratio between primary & secondary systems
Drawback
 Small error ( measuring the still-water level )
 Not significant during the strong vibration

71. History of TLD Sun(1991) : TLD ( SDOF with sinusoidal excitation)
2.6 Tuned liquid dampers
History of TLD
Sun(1991) : TLD ( SDOF with sinusoidal excitation)
Wakahara(1989) : Wind-induced vibration
Welt & Modi(1989a) : Building (wind & earthquake)
Fujino et al(1988) : Behavior (rectangular & circular container )

72. Experiments ( test the validity )
2.6 Tuned Liquid Dampers
Experiments ( test the validity )
Small amplitude  Theory Experiments
Welt & Modi (1989b)’s experiments
Shape : partially filled torus shaped dampers in wind tunnel
Results :
 Damping ratio is sensitive to frequency ratio
max at about 1.0
 Amplitude   Damping 
Fujino (1988)
Shape : cylindrical shaped container on a steel platform
Results :
 At small amplitude the added damping is highly depend on the ratio
of structure to sloshing frequency
( maximum when the ratio )
 At larger amplitude the added damping is reduced and almost
constant for any frequency ratio

73. Sun (1989) Chaiseri et al (1989) Shaking table test on rectangular TLD
2.6 Tuned liquid dampers
Sun (1989)
Shaking table test on rectangular TLD
Verify the accuracy of the simplified theory
Chaiseri et al (1989)
Rectangular container on a SDOF platform
First part
 Varying the water depth at constant amplitude
 Minimum at tuned case
Second part
 Varying the excitation frequency
Result
 Initial condition on structures and waves are not Significant

74. Application Steel frame tower at Nagasaki Airport 50 in height tank
2.6 Tuned liquid dampers
Application
Steel frame tower at Nagasaki Airport
25 tuned sloshing damper
50 in height tank
7 layers - 7cm height
Water depth 4.8cm
Tank diameter 38cm
Mass of water  1.6% of effective mass in fundamental mode
 0.59% of total mass of structure
Result
Critical damping ratio  4.7% with damper (5 times of without damper)

75. Yokohama Marine Tower Case
2.6 Tuned liquid dampers
Yokohama Marine Tower Case
39 tuned sloshing damper
50cm height cylinder container
10 layers of 5cm with water height 2.1cm
Tank diameter 49cm
Total mass of water/tank  1% of effective modal mass
 0.3% of total mass of structure

76. 2.7 Other energy dissipators
Vibration suppression method
Use : bridge cable (aerodynamic vibration)
Shape : cut as V and U stripes (protection tube surface of cable )
Wind test result
Reynold’s number of cable  aerodynamic vibration 
Connecting two adjacent structures
Use : controlling high-rise building during strong earthquake
Method : connecting two adjacent structures with dampers at roofs
Requirement
Different dynamic properties

77. Rubber composite damper
2.7 Other energy dissipators
High damping rubber
Properties : low stiffness & high energy absorption ability
Similar with viscoelastic damper
Material : unvulcanized rubber ( LRB use vulcanized rubber)
Rubber composite damper
Use : cable-stayed bridges
Shape : rubber washer + cable sleeve
Impact damper
Use : highway light poles ( reduce wind vortex-induced oscillations)
Application : particle damper ( consist of four edged brackets )

78. 2.8 Code development and concluding remarks
Tentative requirement
The energy dissipation working group (EDWG)
The base isolation subcommittee
of the structural engineers association of northern california (SEAONC)
Design guide line for wide range of system hardware
(metallic, frictional, viscoelastic, and viscous devices except TMD, TLD)
General concept
Energy dissipators  Inelastic deformation
Main structures  Elastic deformation
Conservative

79. The april 1993 version of tentative requirement
2.8 Code development and concluding remarks
The april 1993 version of tentative requirement
Structures Dynamic analysis
+ Energy dissipation devices
Rate dependent device Response spectrum analysis
(Viscoelastic & viscous dampers)
All rate-independent devices
(metallic damper & friction dampers) Nolinear time history analysis
Inelastic stuructures
Prototype test
General statement about environmental factors
Such as temperature, moisture and creep

80. ATC ( Applied Technology Council)
2.8 Code development and concluding remarks
A second document
By BSSC (Building Seismic Safety Council )
Pronvisions = SEAONC ( in scope & concept )
ATC ( Applied Technology Council)
Developing guidelines
Commentary for seismic isolation & energy dissipation systems

81. 2.6 Tuned liquid dampers

82. 2.6 Tuned liquid dampers