prof.jung july22 apss2010

2010-07-22

1

Structural Controlfor Civil Engineering

Applications

Hyung-Jo Jung

Dept. of Civil & Environmental Engineering

KAIST, Korea

2010 Asia-Pacific Summer School on Smart Structures Technology

The University of Tokyo, Japan

July 15 ~ August 4, 2010

l Overview

l Passive Control

l Active Control

l Hybrid Control

l Semi-active Control

l Summary

CONTENTS

2

l Background

l Motive of Structural Control

l Distinctive Features of Structural Control

l Evolution of Structural Control

l Classification of Structural Control

OVERVIEW

3 4

l Background

Civil Structures: Long-span Bridges

Overview

5

No. Bridge Span[m] Country Year

1 Akashi-Kaikyo 1991 Japan 1998

2 Xihoumen 1650 China 2009

3 Great Belt East 1624 Denmark 19984 Gwangyang 1545 Korea 2012

5 Runyang South 1490 China 20056 Nanjing-4 1418 China 2013

7 Humber 1410 UK 1981

8 Jiangyin 1385 China 1999

9 Tsing Ma 1377 China 199710 Hardanger 1310 Norway 2013

No. Bridge Span [m] Country Year

1 Russky 1104 Russia 2012

2 Sutong 1088 China 2008

3 Stonecutters 1018 China 2009

4 Edong 926 China 2009

5 Tatara 890 Japan 19996 Pont de Normandie 856 France 1995

7 Jingsha 816 China 2009

8 Incheon 800 Korea 20099 Chongming 730 China 2009

10 Minpu 708 China 2009

l Background

Civil Structures: Long-span BridgesSuspension Bridges Cable-stayed Bridges

5

Overview

6

6

l Background

Civil Structures: High-rise Buildings

Overview

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7

l BackgroundCivil Structures: High-rise Buildings

7

Overview

Increase in construction of high-rise buildings

8

Input OutputSystem

Displacement (Safety)

Acceleration (Serviceability)

Excitation ResponseStructure

Vibration Problem of Structures

l Background

8

Overview

Overview

l Background

Seismically-excited Structures

9

Northridge Earthquake, 1994

72 deaths, 1500 injured, 1000s homeless , > $15B cost10

l BackgroundOverview

Great Hanshin Earthquake, Kobe, Japan, 1995

6434 deaths, 35k injured , 300k homeless , > $150B cost

11


Sichuan Earthquake, China (2008)

Estimated losses: 70k deaths , 370k injured, 5.0m homeless


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Other Recent Earthquakes

13

l Background

Kocaeli (Turkey, 1999)Chi-Chi (Taiwan, 1999)

20,000dead20,000dead>$6B damage>$6B damage

Nisqually (Seattle, WA, 2001)

1 death (heart)1 death (heart)400 injured400 injured$1B$1B--$2B damage$2B damage

India (2001)

20,000 (official) 20,000 (official) ––90,000 (unofficial)90,000 (unofficial)deaddead

2500 dead2500 dead10,000 injured10,000 injured100,000 homeless100,000 homeless

230,000 dead230,000 dead125,000 injured125,000 injured1.69 m homeless1.69 m homeless

Sumatra-Andaman (Indonesia, 2004)

Overview

Tacoma Narrows Bridge, Tacoma, Washington

l Background

Wind-excited Structures

14

Overview

Structure & Aerodynamic instabilityphenomenon

15

l Background

Wind-induced vibration

Period of Phenomenon @ Period of Structure(Resonance)

Overview

l BackgroundWind-excited Structures

Tokyo Wan Aqua-line, Tokyo, Japan16

Overview

Tokyo Wan Aqua-line, Tokyo, Japan

17

l BackgroundWind-excited Structures

Overview

After completion of the superstructure, oscillation with an amplitude over 0.5 m was observed.

To suppress it, 16 tuned mass dampers(TMD) were installed.Part of the steed deck was stiffened. 17

Millennium Foot Bridge, London, England

18

l BackgroundHuman-excited Structures

Overview

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l Implementation of passive control systems for retrofitting the bridge§ 37 fluid-viscous dampers (horizontal movement)§ 52 tuned mass dampers (vertical movement)

(www.arup.com/MillenniumBridge/)

l BackgroundHuman-excited Structures

19

Overview

l Increased flexibility¡ the trend toward taller, longer and more flexible structures

l Increased safety levels ¡ higher safety level demands : tall structures, nuclear power

plants

l Increased stringent performance requirements¡ strict performance guide lines: radar tracking stations, radio

telescope structures, aerospace structures

l Better utilization of materials and lower cost¡ economic considerations: savings in materials, weight and

costs

20

Overview

l Motive of Structural Control

l 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.

l Loads are highly uncertain.¡ earthquake and wind loads have no definite magnitude and

arrival time.¡ on the other hand, mechanical loads are fairly well

documented.

l Performance requirements are generally coarse.

l Distinctive Features of Structural Control

21

Overview


Overview

22

Passive Control

Energy dissipation Friction damper

Metallic yield damper

Viscoelastic damper

Energy transfer

TLD

TMD

Structural Control

Viscous fluid damper

Base isolation TLCD

Semi-active Control

Variable orifice damper

Controllable fluid damperMR damper

ER damper

Hybrid Control

Active ControlActive mass driver

Active tendon

Hybrid mass driver

Active base-isolation

Passive, Active, Semi-active Control

Semi-active Controlcontrollablelittle power required

Active Controlcontrollablesignificant power required

Passive Controlnon-controllableno power required


23

Overview

Applicable range of structural control systems

Overview

24


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Overview

25

Applicable range of structural control systems


l The beginning of structural control¡ John Milne (1885): the first example of an isolated building

(a small house of wood on ball bearings)

¡ J. A. Calantarients (1909): a different isolation system to isolate the building from its foundation using layers of talc or mica à building slides during an earthquake.

l Evolution of Structural ControlOverview

26

l Modern structural control concept¡ T. Kobori (1956): proposed a basic concept of active

seismic-response-controlled structure. (the earliest attempt to formulate the problem of active control for applications to civil engineering structures)

¡ J.T.P. Yao (1972): indicated the way to the present active control research in the field of civil engineering.

l Evolution of Structural ControlOverview

27

~1970s 1970s ~ 1990s 1990s ~ 2000s 2010s ~

Passivecontrol

Activecontrol

Semi-activecontrol

Semi-activecontrol???

l Trend of main research topic

l Introduction

l Metallic Yield Dampers

l Friction Dampers

l Viscoelastic Dampers

l Viscous Fluid Dampers

l Tuned Mass Dampers

l Tuned Liquid Dampers

l Base Isolation Systems

PASSIVE CONTROL

28

Energy dissipation(kinetic energy à heat)

Energy transfer

Passive Control Systems

StructureExcitation Response

PED*

M

Passive Damper

M

Base Isolation

M

m

Tuned Mass Damper

* PED: passive energy dissipation 29

l IntroductionPassive Control

l It is usually relatively inexpensive.

l It consumes no external energy (energy may not be

available during a major earthquake).

l It is inherently stable.

l It works even during a major earthquake.

Passive Control

l Introduction

Four Main Advantages of Passive Control

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l Conversion of kinetic energy to heat:

¡ frictional sliding

¡ yielding of metals

¡ phase transformation in metals

¡ deformation of viscoelastic solids or fluids

¡ fluid orificing

l Transferring of energy among vibrating modes:

¡ supplemental oscillators, which act as dynamic vibration

absorbers.

Passive Control

l Introduction

Energy Dissipation Mechanisms

31

Metallic damper

Viscoelastic damper Fluid damper

Theoretical Behavior of Different Types of Dampers(Force-Displacement Response)

Passive Control

l Introduction

32

Friction damper

Time(sec) Time(sec)

En

ergy

En

ergy

without Damper with Damper

Energy Dissipation Performance

kinetic energy

strain energy from elastic and plasticdeformation

damping energy

kinetic energy

strain energy from elastic deformation

damping energy

33

l IntroductionPassive Control

l Inelastic deformation of metallic substances.

l The idea of utilizing added metallic energy dissipatorswithin a structure to absorb a large portion of the seismic energy: the conceptual and experimental work of Kelly et al. (1972) and Skinner et al. (1975).

l Several of the devices considered: torsional beams, flexural beams, and U-strip energy dissipators.

Passive Control

lMetallic Yield Dampers

34

Passive Control


Behavior of a damper:Bending under horizontal load

플레이트형ADAS 장치

P

ADAS 장치

보

브레이스

P

P

Installation

Plate-type ADAS

35

The area within the hysteresis loops measures the amount of dissipated energy.

36

lMetallic Yield DampersPassive Control

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• A triangular plate damper or triangular added damping and stiffnessdevices (TADAS)

37


38

Low-yield strength steel

42-story high-rise RC condominium

Tennozu Project

Copyright 2008 Shimizu Corporation, All Rights Reserved


38

Honeycomb Damper Installation of Honeycomb Damper

39


lFriction Dampers

l Friction:

¡ an excellent mechanism for energy dissipation

¡ used for many years in automotive brakes to dissipate kinetic energy

l It is important to minimize stick-slip phenomena to avoid

introducing high-frequency excitation.

l Compatible materials to maintain a consistent coefficient of

friction over the intended life of device

l Not to slip during wind storms or moderate earthquakes.

à under severe loading conditions, the devices slip at a predetermined

optimum load before yielding occurs in primary structural members.

40

lFriction Dampers

41

Passive Control

l Pall-Friction Damper

41

Disc Springs

Friction Pad Material

Bolt

Steel Plate

Hard Steel Washer

Nut

Steel Plate

Hinge

lFriction Dampersl Rotational Friction Damper

42

Passive Control

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Mechanism of the Damper

This new friction damper device is based on rotational friction and designed to:• be stable in performance over many cycles• be compact• be easy to manufacture• be fast and simple to install (no need for a qualified staff)• be requiring little or no maintenance• be inexpensive

TensionRotationRotation

TensionTension

Force

Mechanism of the Damper

Force

43

lFriction Dampersl Rotational Friction Damper

Passive Control Passive Control

lViscoelastic Dampers

44

l Metallic and frictional devices: seismic application

l The VE dampers: applications in both wind and seismic protection

ß VE solid materials can be used to dissipate energy at alldeformation levels

l Characteristics of VE materials1) rate dependent behavior (viscous)2) elastic behavior (elastic) 3) store and dissipate energy at all deformation levels

Steel Plate

Viscoelastic Material

P

P

⇒

Deformed

Steel flangeCenter plate

VE MaterialCenterplate

Steelflange

VE Material

F/2 F/2

F

Typical Hysteretic Loops

Typical Viscoelastic Damper

VE dampers dissipate energy through shear deformation of the VE layers. 45

lViscoelastic DampersPassive Control Passive Control


46

l World Trade Center in New York (1969)

ViscoVisco--elastic elastic damperdamper

• 10,000 Visco-elastic dampers in each tower• Evenly distributed from 10th to the 110th floor• Damping: 2.5%~3%

l The Columbia SeaFirst Building in Seattle (1982)

→ 260 viscoelastic dampers → to reduce wind-induced vibration

VE Damper

47

lViscoelastic DampersPassive Control

l The Two Union Square Building in Seattle (1988)

→ 16 large dampers were installed parallel to four columns

in one floor

→ to reduce wind-induced vibration 48

lViscoelastic DampersPassive Control

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Wall TypeWall Type

Brace TypeBrace Type C BuildingC Building

M Department StoreM Department Store

Visco-elastic Material

Copyright 2008 Shimizu Corporation, All Rights Reserved 49


粘

弾

性

体

鋼

板

Ｑ

Ｑ

鋼

板

ｖ（速度）

せん断ひずみ γ＝δ／ｄ

ｄ（厚さ） δThickness Thickness (t)(t)

deformation deformation (d)(d)

Shear Strain g = Shear Strain g = d/td/t

Steel Steel PlatePlate

Shear Shear Force (Q)Force (Q)

Steel Steel PlatePlate

ViscoVisco--elastic Materialelastic Material

Shear Shear Force (Q)Force (Q)

50

VE damper 설치 위치

Implementation of VE Damper

core wall

column

wide beam


l Galleria Palace in Seoull Full-scale 5 story steel tower

K.W. Min (Dankook Univ., Korea)

Passive Control

lViscous Fluid Dampers

l The action of solids (inelastic deformation): metallic, friction and viscoelastic dampers

l The action of fluids: viscous fluid dampers (e.g., the auto-motive shock absorber)

l Viscous fluid dampers, widely used in aerospace and military applications, have recently adapted for structural applications.

l Most viscous fluid dampers in current applications

( 0.3 £ n £ 0.75 )

• obtained by special design of the orifices

• advantages : the force tends to flatten out at higher velocities

noVCF =

l For low damping force rate, a simplified force-velocity relationship

XCF &0=

where C0 is independent of the frequency but dependent on ambient temperature

51

Passive Control

Seismic fluid viscous damper, 50,000 pounds output Seismic fluid viscous dampers for large highway bridge, 1.5 million pounds output force

Seismic fluid viscous dampers, 1.3 and 2.0 million pounds output


52

Passive Control

Seismic Design with Fluid Dampers as Part of a Base Isolation System

the new San Bernardino County Medical Center at Colton, California (1994)

nearly 200 pieces of a 320,000 lb. output Fluid Viscous Damper.

All buildings are base isolated on large rubber bearings, with dampers mounted in parallel with the bearings


53

Passive Control

l 3-Story Pacific Bell North Area Operations Center (1995)

→ 62 Dampers ( each damper : capacity = 130kN , stroke=50mm)

(a) Under Construction (b) Damper installation


54

Passive Control

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• Seismic Damper Installation at the New Pacific Northwest Baseball Park

- The dampers are used for seismic protection of the roof during earthquakes.- 3600 kN eight dampers with stroke of ±381mm


55

Passive Control

Seismic Rehabilitation of an Historic Structure

This is an historic structure, and the owner wished to minimize changes to the building's appearance.


56

Passive Control

l The objective of incorporating a TMD into a structure:

to reduce energy dissipation demand on the primary structural members under the action of external forces.

l The mechanism of a TMD:

transferring some of the structural vibrational energy to the TMD which consists of an auxiliary mass-spring-dashpot system anchored or attached to the main structure.

l The modern concept of TMDs for structural applications

(Frahm 1909)

Passive Control

lTuned Mass Dampers (TMD)

57

Classical Undamped Tuned Mass Damper (TMD) (or Dynamic Vibration Absorber (DVA))

• An undamped main mass-spring system under a sinusoidal force F0sinwt

- the forcing frequency (w) = the natural frequency of the main mass (wn=Ök/m)

à the response is infinite (i.e., resonance)

à it can cause severe problems for vibrating systems.

x

k

m

58

Passive Control


• When an absorbing mass-spring system (i.e. TMD) is attached to the main mass and the resonance of the TMD is tuned to match that of the main mass

(i.e., wn = wTMD =w)

à the motion of the main mass is reduced to zero at its resonance frequency.

à the energy of the main mass is apparently "absorbed" by the TMD.

x(t) = Xsin wt = 0

xa(t) = Xasin wt = -(F0/ka)sin wt

ka

ma

k

m

59

Passive Control


60

Animation of the main mass and TMD at three frequencies.

• The 2-DOF system has two natural frequencies, corresponding to the two natural modes of vibration for the system.

In the lower frequency mode, both masses move in the same direction, in-phase with each other.

In the higher frequency mode the two masses move in opposite direction, 180° out of phase with each other.

undamped classical tuned mass damper

w < wn w > wnw = wn

60

Passive Control


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Displacement vs. Frequency plots:

• The plots below show the displacements as a function of normalized frequency (driving frequency divided by natural frequency of main mass).

- The blue dashed curve: the displacement response of the undamped main mass alone. - The blue curve: the displacement of the main mass after undamped TMD has been attached.

(A TMD mass (20% of the main mass) is tuned to the resonance frequency of the main mass.)- The red curve: the displacement of the absorber mass.

- Notes:(1) the main mass has zero displacement at the original problem frequency. (2) there are now two new resonance frequencies.(3) the displacement of the TMD mass is infinite at the same two resonance frequencies.(4) the response at the target frequency is finite (approximately 4.8).

main massdisplacement

TMDdisplacement

61

Passive Control

lTuned Mass Dampers (TMD)l Citicorp Center in New York, USA

62

Passive Control


l John Hancock Tower in Boston, USA

63

Passive Control

lTuned Mass Dampers (TMD)• Chiba Port Tower,

Tokyo Bay, Japan

64

Passive Control


l Supplementary damping¡ Towers: not necessary

¡ Sky bridge: 3 TMDs per each leg. (73 kg ea)

¡ Pinnacles: simple chain impact dampers

TMD

Petronas Towers: TMD

65

Passive Control


66Building TMDBuilding TMD

Pinnacle TMDsPinnacle TMDs


66

Taipei 101, Taiwan

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l Building TMD in Taipei 101¡ 660 ton. (0.24% of building mass)

Worlds largest.¡ TMD and its support occupy five

upper floors.¡ Visible from a mezzanine level.¡ $3.5-million turnkey contract.

§ Includes Dampers and 60m tall pinnacle.

§ Additional $800k for the damper ball.

¡ Made of 12.5 cm thick steel plate.¡ Peak acceleration of the top was

reduced from 7 mili-g to 5 milli-g.¡ The damper will not have any role

during earthquakes?


67

l Pinnacle TMDs¡ Two 4.5 ton dampers

¡ Flat steel masses tuned by springs are able to move horizontally in any direction.

¡ To reduce cumulative fatigue damage due to wind-induced motion.

68

Passive Control


Park Tower Hotel & Residences

l Chicago, Illinois, United States

l 70 story multi-use building

¡48 stories of condos over 18 story hotel

l 824 ft. tall tower

l 5 story parking garage

l Building was designed with a tuned mass damper to control lateral accelerations

CSA

69


70

Park Tower Hotel & Residences

CSA

70


l Modified structure¡ Initial structural properties:

lT = 7.26 seclDrift = 13” = h/700lAcceleration = 35 mg

¡Final structural properties without damper:lT = 5.18 seclDrift = 9.7 in. = h/940lAcceleration = 20.7 mg

¡With addition of damper:lAcceleration = 15 mg

CSA

71


Park Tower Hotel & Residences l TMD for Wind Vibration Control of Apartments

(Posco E&C; TE Solution, Korea)

Centum Park Apartments (Busan, Korea)

4.95

2.98

3.41

5.18

3.12

3.41

4.87

2.94

3.41

0

1

2

3

4

5

6

accele

ration[gal]

No.101 No.103 No.105

without TMD with TMD ISO6897

Passive Control


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l Liquids are used to provide all of the necessary characteristic of the secondary system.

l The liquid not only supplies the required secondary mass, but also the damping through viscous action primarily in the boundary layers.

l Gravity provides the necessary restoring mechanism.

Passive Control

lTuned Liquid Dampers (TLD)

l In TMD, typically a solid concrete or metal block acts as the secondary mass.

73

TSD

(Tuned Sloshing Damper)

TLCD

(Tuned Liquid Column Damper)

TLD

§ Haneda Airport Air Traffic Control Tower (1993, H=77.6m)

74

Passive Control


Super Sloshing Damper

Tokyo Dome Hotel

75


¡ Two TLCDs at the roof level (290 tons and 430tons)

¡ Large U-shaped tanks at right angles.¡ Moving water mass is 550 tons (0.33% of

building weight) in each tank.¡ Cost effective. Cheaper than a pendulum

TMD.


l Tuned Liquid Column Damper in Random House

76

77

0 20 40 60 80-0.5

0

0.5

Time (sec)

Acc

. (m

/sec

2 )

UncontrolledControlled

0 1 2 30

0.1

0.2

0.3

0.4

0.5

Frequency (Hz)

Pea

k A

cc. (

m/s

ec2 )

UncontrolledControlled

(POSCO E&C and RIST, Korea)

Test ResultsSmall-scale Experimental Test

Passive Control


l TLCD for Wind Vibration Control of Apartments l One of the most widely implemented and accepted control strategies

l Decouple the structures and/or its components from potentially damaging earthquake-induced ground or support motions .

l Allow large deformations of control devices to achieve these goals.

Acceleration response spectrum Displacement response spectrum

Period shift

Period

Acc

eler

atio

n

Dampingeffect

Period shift

Period

Dis

plac

emen

t

Dampingeffect

Passive Control

lBase Isolation System

78

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• During an earthquake, a fixed-base building can sway from side to side.

• When a base isolation system is used, the sideways movement occurs mainly in the bearings, and the building hardly distorts at all.

79

Base Isolation SystemPassive Control

l Basic requirements of base isolation

l Seismic behavior of base isolated structures

1. Flexibility

2. Energy dissipation capacity

3. Sufficient stiffness under small load

Passive Control


80

Conventional bridges with earthquake resistant designHorizontal force is concentrated on a rigid pier.

81

Passive Control


Load dispersing bridge (Base Isolated)RB and LRB are used to disperse the horizontal force induced on each pier.

82

Passive Control


Seismic isolation bridgeLRB is used to increase the vibration period and damp the vibration.

83

Passive Control


Square Base Isolators made of Multilayer Natural Rubber with an internal Lead Plug

84

Passive Control


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Function

Multi-layer rubber isolator Function

(1) Load supporting / Rotation Absorbing function

- Rubber reinforced with steel plates provides stable support for structures- Multilayer construction provides better vertical rigidity than single layer rubber pads for supporting a building.

85

Passive Control


(2) Horizontal elasticity function (prolonged oscillation period)- Earthquake vibration is converted to low speed motion- As horizontal stiffness of the multi-layer rubber bearing is low, strong earthquake vibration is alleviated and the oscillation period of the building is increased.

(3) Restoration function- Horizontal elasticity returns the building to its original position.- After an earthquake the restoring force of the rubber layers returns the

building to the original position.86

Passive Control


Function of lead plug (damper)

(4) Vibration damping function- It absorbs large vibration of the structure- As the layers of rubber are distorted, the lead plug is plastically deformed, which

absorbs the earthquake energy and quickly damps the vibration.

(5) Trigger function- Reduces vibration from sources other than earthquake.- Vibration generated by strong winds are avoided as the relative rigidity of the lead

plug restricts the flexibility of the isolation system until the plug is subjected to a certain level of force. 87

Passive Control

lBase Isolation SystemPassive Control

88

USC Hospital(First base-isolated hospital in U.S.)

New LA Cathedral(under construction)

LA City Hall(in retrofit)

rubber bearings

friction pendulum bearings

bearings in basement


Base-isolated Condominiums

89

Passive Control

lBase Isolation SystemLead Rubber Bearings (LRB) in Bridges Base Isolators in Bridges

90

Passive Control


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Example: LNG Tank

91

Passive Control

lBase Isolation SystemExample: Tohoku Univ.

Acceleration resp. of left bld.

Acceleration resp. of right bld.

92

Passive Control


l Introduction

l Actuators

l Control Algorithms

l Full-scale Applications

ACTIVE CONTROL

Active Control

93


Computer

Control Actuators

Sensors

FeedbackLink

Sensors

FeedforwardLink

Active Control Systems

94

l IntroductionActive Control

Active Bracing

M

Actuator

Sensor

Active Mass Damper

M

Actuator Sensors

m

Control Computer


95


l Initial concept paper: J.T.P. Yao (1972)

l An external source powers control actuator(s) that apply forces to the structure in a prescribed manner.

l Control forces can be used to both add and dissipate energy in the structure.

l In an active feedback system, the signals sent to the control actuators are a function of the response of the system measured with physical sensors (optical, mechanical, electrical, chemical, and so on).


96


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l Advantages (attractive features):¡ enhanced effectiveness in motion control

¡ relative insensitivity to site conditions and ground motions

¡ applicability to multi-hazard situations

¡ greater ability to select control objectives

l Disadvantages (issues to be solved):¡ Capital cost and maintenance

¡ reliance on external power

¡ system reliability and stability

¡ gaining acceptance by the profession


97

Active Control

98

l Introduction

l Active structural control is not popular for seismic hazard mitigation because¡ Energy consumption during seismic events, when power blackout

is highly likely to occur

¡ Stability concern: what if the control system becomes unstable?

l Active structural control is still very useful for reducing wind-induced vibrations in bridges and buildings¡ Active mass damper (AMD)

¡ Hybrid mass damper (HMD)

Active Mass Driver (AMD) Experiment:Acceleration Feedback Control Strategies

Control Computer/DSP Board

)(act tz

)(a1 tz&&

)(g tz&&

)(a3 tz&&

)(a2 tz&&

Active Control

l Introduction

99(B.F. Spencer, Jr., UIUC)

2 translational1 translational &

rotational2 translational &

rotational

Arrangement of AMD


100

lControl AlgorithmsActive Control

101

l Optimal Control

l Stochastic Control

l Adaptive Control

l Intelligent Control§ Neural network-based control (i.e., neuro-controller)

§ Fuzzy logic-based control (i.e., fuzzy controller)

l Sliding Mode Control

l Robust Control

Kyobashi Seiwa Building (1989)

AMD-1

AMD-2Control Computer

Sensor

Sensor

Sensor

lFull-scale ApplicationsActive Control

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Kyobashi Seiwa Building (1989)


103

Yokohama Landmark Tower (1993): AMD


104

Shinjuku Park Tower (1994): AMD

lFull-scale Applications

105

Active Control

0 500 1000 1500 2000 2500 3000-10

-5

0

5

10Bending 23F X-dir

x uncont

x cont

0 500 1000 1500 2000 2500 3000-5

0

5Bending 23F Y-dir

y uncont

y cont

0 500 1000 1500 2000 2500 3000-4

-3

-2

-1

0

1

2

3Rotation 23F

theta uncont

theta cont

AMD for Wind Vibration Control of Building in Use(2007)

0 10 20 30 40 50 60 70 80 90 100-10

0

10

Accele

ration

G

al

Unit No. 1 side

0 10 20 30 40 50 60 70 80 90 100-10

0

10

Accele

ration

G

al

Unit No. 2 side

0 10 20 30 40 50 60 70 80 90 100-20

0

20

Dis

pla

cem

ent

cm

Unit No. 1

0 10 20 30 40 50 60 70 80 90 100-20

0

20

Time s

Dis

pla

cem

ent

cm

Unit No. 2

0 10 20 30 40 50 60 70 80 90 100-10

0

10

Acc

eler

atio

n

Gal

Unit No. 1 side

0 10 20 30 40 50 60 70 80 90 100-10

0

10

Acc

eler

atio

n

Gal

Unit No. 2 side

0 10 20 30 40 50 60 70 80 90 100-40

-20

0

20

40

Dis

plac

emen

t

cm

Unit No. 1

0 10 20 30 40 50 60 70 80 90 100-40

-20

0

20

40

Time s

Dis

plac

emen

t

cm

Unit No. 2

Numerical VerificationFree Vibration TestUncontrolled case Controlled case

AMD System

Active Control

106


(Lotte E&C and KAIST)


(Lotte E&C and KAIST)

Reinforcement Lifting Temporary Hoist Frame

Assembling Control Panel Completion

Active Control

AMD for Wind Vibration Control of Building in Use(2007)

HYBRID CONTROL

l Introduction

l Hybrid Mass Damper (HMD)

l (Semi-)Active Base Isolation

l Full-scale Applications

108

2010-07-22

19


Computer

Control Actuators

Sensors

FeedbackLink

Sensors

FeedforwardLink

Hybrid Control Systems(passive devices + (semi-)active system)

109

PED

lIntroductionHybrid Control

l The combined use of active and passive control systems

l For example, ¡ a structure equipped with distributed viscoelastic damping

supplemented with an active mass damper on or near the top of the structure

¡ A base isolated structure with actuators actively controlled to enhance performance

¡ The hybrid mass damper (HMD) is a combination of a TMD and an active control actuator, which is the most common control device employed in full-scale civil engineering applications.

Hybrid Control Systems

110


(Semi-)Active BaseIsolation

M

Actuator or MR damper Sensor

Control Computer

Hybrid Control Systems

111


Hybrid Mass Damper

MActuator

Sensorsm

l The most common control device in full-scale structure

l HMD = TMD + active control actuator

l Advantages- compact

- efficient

- practically implementable

lHybrid Mass Damper (HMD)

• DUOX HMD

- high control efficiency with a small actuator force

Hybrid Control

112

20 40 60 80 100 120 140-0.10

-0.05

0.00

0.05

0.10

Accel

eratio

n (m/

s2 )

Time (sec)

TMDmode Uncontrolled

x

y

HMD1

HMD2

Air Traffic Control Tower: 100. 4 mNatural Freqeuncy: 0.71 Hz

Location of HMDs: 19th Floor (80 m above ground)

20 40 60 80 100 120 140-0.10

-0.05

0.00

0.05

0.10

Accel

eratio

n (m/

s)

Time (sec)

Controlled byHMD mode

Hybrid Mass Damper (HMD)

HMD for Air-traffic Control Tower (Incheon Int’l Airport)

Signal w/o HMD Signal w/ HMD

Hybrid Control

113


114

l Active tuned mass damper¡ Two dampers on the 90th floor.

¡ Sensors are used to measure the building sway with a computer to control

• Shape– The Hole in the building reduces vortex-

shedding induced force.

Shanghai World Financial Center: HMD

lFull-scale ApplicationsHybrid Control

2010-07-22

20

Hybrid (or Smart) Base Isolation

MR Damper

gx&&

115(B.F. Spencer, Jr. (UIUC))

Experimental Setup

[parameters of the experimental model]• mass of the base: 10.5 kg• mass of the structure: 57.5 kg• total mass: 68 kg

• Max force of the MR damper (at current of 0.5 A): 45 N6.6 % of the total mass


Experimental Setup

%5.3Hz),(3.88Hz65.11%0.1,Hz)(0.47 Hz42.1

22

11

====z

zff


Structural Acceleration

-0.15-0.1

-0.050

0.050.1

0.15

0 2 4 6 8 10

Acc

eler

atio

n [g

]

-0.4-0.2

00.20.4

0 2 4 6 8 10

Acc

. [g] Max: 0.2g(0.44g for full scale)

Response to Strong Earthquake

Without damper

Optimal passive(constant voltage)

Smart damping

28 % reduction (Peak)29 % reduction (RMS)


Input Motion (El Centro NS)


-0.04-0.02

00.02

0.04

0 2 4 6 8 10

Acc

eler

atio

n [g

]

Structural Acceleration

Without damper

Optimal passive(constant voltage)

Smart Damper

49 % increase (Peak)49 % increase (RMS)


Input Motion (El Centro NS)

Max: 0.07g(0.15g for full scale)

Response to Moderate Earthquake

-0.4-0.2

00.20.4

0 2 4 6 8 10

Acc

. [g]


SEMI-ACTIVE CONTROL

l Introduction

l MR Fluids and Dampers

l MR Damper-based Control Systems

l Control of Cable Vibration

l Limitation of Semi-active Control

120

2010-07-22

21

Semi-active Control Systems


Sensors SensorsComputer

Control Actuators

PED

121

lIntroductionSemi-active Control

Semi-active Control Devices® combine the best features of both passive and active control

® don’t require large power sources : can operate on battery power, which is critical during seismic events when the main power source to structure may fail

® performance is better than passive devices and have potential to achieve similar performance with fully active devices

Definition

¡ cannot inject mechanical energy into the controlled structure, but has properties that can be controlled to optimally reduce the responses of the system

®have no potential to destabilize the structural system

(Bounded Input-Bounded Output stability)

Semi-active Control

lIntroduction

122

Control Computer

Semi-active Control Systems

123

Smart Base Isolation

MMR elastomer

Sensor

Semi-active TMD

M

MR damper Sensors

m


Semi-active damper

M

MR damper

Sensor

Control Computer

Smart Damping?


124

Smart Damping?


125

Smart Damping?


126

2010-07-22

22

127

Kajima Shizuoka Building:Observations from the May 7, 1999 M4.9 Earthquake

Full-scale Applications


lK-Building

Hybrid mass damper: 2

Semi-activehydraulic damper: 88

238.05m, 54 story

Semi-activehydraulic dampers: 356

lR-Building

Full-scale Applications


128

• Micron-sized, polarizable, iron particles in oil

l What do they do?

• Newtonian in the absence of applied field

• Develop yield strength when field applied

• Provide reliable means for a low-power, rapid response interface between electronic controls and mechanical devices

l What are they?

Semi-active Control

129

MR Fluids


l Magnetorheological (MR) dampers are semi-active control devices that use MR fluids to produce controllable dampers.

l Attractive features:– High dissipative force at low velocity.

– Continual optimization.

– High dynamic range

– Inherent stability and failure-safety.

– Mechanical simplicity.

– Fast response-time.

– Small device size.

– Large temperature range.

Semi-active Control

130

Annular Orifice

l MR Fluids and DampersMR Dampers

MR Fluid Linear Damper:- used in semi-active suspension system

- used in highway vehicle seats

Semi-active Control

131


Responses due to 120% El Centro Earthquake

Measured Response• 75% reduction in peak displacements• 50% reduction in peak accelerations• 30% better response reduction than when

device is operated in passive capacity

CurrentDriver

ControlComputer

Rheonetic SD-1000MR Damper

3-Story Scale-Model Building

Height: 158 cmMass: 304 kg

gx&&

dxf ,

1ax&&

2ax&&

3ax&&

lMR Damper-based Control SystemSemi-active Control

132(B.F. Spencer, Jr., UIUC)

2010-07-22

23

Nihon-Kagaku-Miraikan, Tokyo

National Museum of Emerging Science and Innovation Two 30-ton, MR Fluid dampers b

uilt by Sanwa Tekki using Lord MR fluid are installed between 3rd and 5th floors

Full-scale Applications: Building

133

Semi-active Control

lMR Damper-based Control System

134

Semi-active Control

lMR Damper-based Control SystemFull-scale Applications: Base-isolated Building

Existing solutions:• Cable restrainers which tie

together cables

• Altered surface roughness on cables

Control of Stay Cable Vibration using MR Dampers

Dampers

Bridge Deck

Standard Solution

• Augment damping through discrete viscous dampers attached transverse to cable

New Solution

lControl of Cable VibrationSemi-active Control

0 1000 2000 3000-20

-10

0

10

20

(a) A10 In-Plane Time (s)

Acc

eler

atio

n (m

/s2 )

0 1000 2000 3000-20

-10

0

10

20

(b) A10 Out-of-Plane Time (s)

Acc

eler

atio

n (m

/s2 )

0 1000 2000 3000-20

-10

0

10

20

(c) A11 In-Plane Time (s)

Acc

eler

atio

n (m

/s2 )

0 1000 2000 3000-20

-10

0

10

20

(d) A11 Out-of-Plane Time (s)

Acc

eler

atio

n (m

/s2 )

0 1000 2000 3000-20

-10

0

10

20

(e) A12 In-Plane

Acc

eler

atio

n (m

/s2 )

0 1000 2000 3000-20

-10

0

10

20

(f) A12 Out-of-Plane Time (s)

Acc

eler

atio

n (m

/s2 )

Time (s)

Acceleration time-history response (0s ~ 2600s)

A10

(without damper)

A11

(With Twin-damper)

In-plane Out-of-plane

A12

(without damper)

II

In-plane accelerometer

Out-of-plane accelerometer

MR damperDisplacement transducer

Damper Installation and Test Results

(Y.Q. Ni, 2001)

Semi-active Control

lControl of Cable Vibration

Field Test Results

(Y.Q. Ni, 2001)

0.000.100.200.300.400.500.600.70

0 4 8 12

Voltage (v)

Dam

ping

Rat

io (%

)

Single Damper Without Damper

Damping ratios of 1st in-plane mode under vibration amplitude 0.04~0.07 m/s2

Semi-active Control

lControl of Cable VibrationFull Installation and Verification

(Y.Q. Ni, 2001)

Semi-active Control

lControl of Cable Vibration

2010-07-22

24

§ It requires a feedback control system including sensors, a controller and an external power source.

§ It is difficult to install and maintain the conventional smart system, especially in the cases of large-scale structures such as long-span bridges.

Maintenance and Implementation Issues

lLimitation of Semi-active Control

139

Semi-active Control

: Functionally upgraded passive (or smart passive) devices

§ Approach 1: passive devices having adaptability

- Can mimic the function of semi-active devices.

§ Approach 2: simpler semi-active control devices

- Wireless sensor network

- Decentralized control

- Energy harvesting

lLimitation of Semi-active Control

How to Solve the Problems(Future Direction of Structural Control)

Semi-active Control

140

à Adaptive Negative Stiffness System (Nagarajaiah, Rice U.)

à MR damper with Electromagnetic Induction Device (Jung, KAIST)

lLimitation of Semi-active ControlExample: MR Damper with Electromagnetic Induction

(EMI) Device (H.-J. Jung): one possible approach

MR Damper

´ ´ ´´´ ´ ´´´ ´ ´´´ ´ ´´´ ´ ´´´ ´ ´´´ ´ ´´´ ´ ´´

´ ´´´ ´´´ ´´´ ´´´ ´´´ ´´´ ´´´ ´´

damper deformation

magnetic field

Induced

current

EMI system

Proposed system

Preliminary Performance Test using Large-scale Shaking Table

MR Dampercontroller

power source

command

current

Control System

sensor

Conventional system

-8

-4

0

4

8

0 2 4 6 8 10 12 14

time (sec)

disp

lace

men

t at 1

st fl

oor

(mm

)

uncontrolled smart passive system

-1.6

-0.8

0

0.8

1.6

0 2 4 6 8 10 12 14

time (sec)

indu

ced

curre

nt(A

)

Induced current from EMI system

Displacement at 1st floor

Semi-active Control

l Structural control technologies has been developed to to mitigate vibration of civil engineering structures such as bridges and buildings.

l Structural control can improve serviceability as well as safety of structures.

l Semi-active control is promising for civil engineering applications. However, limitation in implementation and maintenance should be resolved. à Smart passive control

SUMMARY

142

u Spencer, B.F., Jr., “Current Practice and Future Trends in StructuralControl,” Lotte Symposium, 2008.

u Housner, et al., “Structural Control: Past, Present, and Future,”Journal of Engineering Mechanics, ASCE, 123(9), 1997

u T.T. Soong, Active Structural Control: Theory and Practice,John Wiley & Sons,1990.

u T.T. Soong and G.F. Dargush, Passive Energy Dissipation Systems in Structural Engineering, John Wiley & Sons, 1997.

REFERENCES

143

prof.jung july22 apss2010

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