current practice and future trendscurrent practice and...

Current Practice and Future TrendsCurrent Practice and Future Trends in Structural Control

B.F. Spencer, Jr.p ,

Nathan M. and Anne M. Newmark Endowed Chairin Civil Engineeringin Civil Engineering

University of Illinois at Urbana-Champaign

sstl.cee.Illinois.edusstl.cee.Illinois.edu

Outline

• What is the current status of vibration l h l f i il i icontrol technology for civil engineering

applications?

• What are the next steps and the mostWhat are the next steps and the most promising future control technologies?

A Brief Historical Perspective

• What is a (feedback) control system?N Wiener described it as “a method of controlling a- N. Wiener described it as a method of controlling a

system by reinserting into it the results of its past performance.”p f

Simple Diagram for Structure ControlSimple Diagram for Structure Control

Application of feedback principles had its beginnings in simple machines and instruments some of them going back centuriesmachines and instruments, some of them going back centuries, e.g., water-clock, thermostat, windmill, and flyball governor.

Ktesibios’ Water Clock (~300 B.C.)Ktesibios’ Water Clock (~300 B.C.)Watt’s Flyball Governor (1788 A.D.)Watt’s Flyball Governor (1788 A.D.)

• The theoretical study of feedback control came relatively late• The theoretical study of feedback control came relatively late in the development of science and technology.

- 1840: Airy, centrifugal-pendulum governor analysis

- 1868: Maxwell: flyball stability analysis

- 1877: Routh, stability analysis

- 1890: Liapunov nonlinear stability analysis- 1890: Liapunov, nonlinear stability analysis

- 1927: Black, electronic feedback amplifier

- 1932: Nyquist, Nyquist stability criterion

- 1938: Bode, frequency response methods

- 1942: Wiener, optimal filter design

-1956: Pontryagin, maximum principle

-1957: Bellman, dynamic programming

-1960: Kalman, optimal estimation techniques

CControl ontrol is an instance of is an instance of technology technology giving giving birth to science!birth to science!

Why Structural Control for Civil I f t t ?Infrastructure?

• Civil engineering structures are exposed to g g ppotentially hazardous loadings such as earthquake and wind

• Control technologies can improve the safety and i bilit f th t tserviceability of the structure

C t t hi di t d t t l di• Catastrophic disasters due to extreme loadings can be prevented

• Lifecycle costs can be reduced

Seismically Excited Structures

Wind Excited Structures

Tacoma Narrows Bridge, Tacoma, Washington


Tokyo Wan Aqua-line, Tokyo, Japan

Human Excited Structures

Millennium Foot Bridge, London, England

C ti f i ldConservation of energy yields:

dE+hsk EEEE ++=

• E = total energy input to the structure from excitationgy p f• Ek = kinetic energy of the structure• Es = elastic strain energy of the structure

• Ed = energy dissipated by supplemental damping

s gy f• Eh = energy dissipated due to inelastic deformation

d gy y gdevices

Supplemental Damping DevicesSupplemental Damping Devices

Active Control Systemscontrollable

Passive Systemsnon-controllable

significant power requiredno power required

“Smart” Damperscontrollable

little power requiredlittle power required

Conventional Structure

Excitation ResponseStructure

M

Passive Control Systems

PED

StructureExcitation Response

m

MMMM

Passive DamperBase IsolationTuned Mass Damper


• Dampers • Base IsolationBase Isolation• Tuned Mass Damper• Tuned Liquid Damper /

Tuned Liquid Column Damperu ed qu d Co u pe• Aerodynamic Shaping• Nonlinear Energy Sink

World Trade Center in New York

•10,000 Visco-elastic dampers in each tower•Evenly distributed from 10th to the 110th fl110th floor•Damping: 2.5%~3%

ViscoVisco--elastic elastic dddamperdamper

ViscoVisco--elastic Damperelastic Damper

ViscoVisco--elastic elastic MaterialMaterial

Brace TypeBrace Type C BuildingC Building

粘Ｑ鋼

Steel Steel Shear Shear Force (Q)Force (Q)

Steel Steel PlatePlate

ViscoVisco--elastic Materialelastic MaterialBrace TypeBrace Type C BuildingC Building

粘

弾

性

体

鋼

板

Ｑ

Ｑ

鋼

板PlatePlate Force (Q)Force (Q)PlatePlate

Shear Shear Force (Q)Force (Q) 体板

Ｑ

ｖ（速度）

せん断ひずみ γ＝δ／ｄ

ｄ（厚さ）Thickness (d)Thickness (d)

deformation deformation (d)(d)

(Q)(Q)

Thickness (d)Thickness (d)Shear Strain g = d/dShear Strain g = d/d Wall TypeWall Type M Department StoreM Department Store

Steel Damper

Low-yield strength steel TennozuTennozu ProjectProject

42-story high-rise RC condominium

Use of Dampers in High-rise Buildingin High rise Building

Dissipate energy of Dissipate energy of relative vertical relative vertical motion between motion between

perimeter columns perimeter columns and outriggersand outriggers

Vertically acting Vertically acting dampers between dampers between

coupled shear wallscoupled shear wallscoupled shear wallscoupled shear walls

Beam-type Steel Dampers in RC Core WallsCore Walls

超高強度RCコアウォール

（最大強度80N/mm2）

2525

4650

4650

4650

4650

23650

境界梁型制震ダンパー

3450 34506000 6000 6000 600030900

2525

4650

RCコアウォール超高強度

ウ

制震ダンパー境界梁型

Damped Outrigger Implementation

St. Francis Shangri-La Place, Manila, Philippines

Outrigger Layout

Passive Control System



Seismic Isolation Methods for High-rise RC CondominiumsHigh rise RC Condominiums

Base Isolation Device (A total of 32)

Mat slab

35 story RC condominium

Oakland City Hally

Earthquake Response

Fixed Base Base Isolated

Base-isolation of LNG Tanks2828

ffSLIDINGSLIDING ffBIBI ffNONNON--BIBI

Laminated Rubber Bearings

Base-Isolated Display-Table for Museumfor Museum

Display Tables on Shaking Table

(Y. S. Kim & S. J. (Y. S. Kim & S. J. JooJoo : TS Solution): TS Solution)

Display-Tables on Shaking Table(Hyundai E&C)

Performance of Base Isolation

2D El Centro Record (PGA=0.6g)( g)

Without Base-isolator

WithBase-isolator

Taipei 101: TMD

Pinnacle TMDsPinnacle TMDs

Building TMD

Taipei 101: Building TMD

• Building TMD– 660 ton. (0.24% of building mass)

Worlds largest.– TMD and its support occupy five upper pp py pp

floors.– Visible from a mezzanine level.

$3 5 million turnkey contract– $3.5-million turnkey contract.• Includes Dampers and 60m tall

pinnacle.Addi i l $800k f h d b ll• Additional $800k for the damper ball.

– Made of 12.5cm thick steel plate.– Peak acceleration of the top was reduced p

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

earthquakesea t qua es

Taipei 101: Pinnacle TMDs

• Pinnacle TMDsT 4 5 t d– Two 4.5 ton dampers

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

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

Tokyo BayTokyo Bay Crossing Bridge in 1997

34

16 TMD’s were installed for controlling

the first and second modes

TMD35

w/o TMD With TMDComparisonWind direction under similar

wind conditions

Wind speed Before AfterWind speed Before After

GirderGirder vibration

MotionTMD amp

Motion of TMD

36

TMD amp.

PARK TOWER HOTEL & RESIDENCES CSAHOTEL & RESIDENCES

• Chicago, Illinois, United States• 70 story multi-use building

– 48 stories of condos over 18 story hotel• 824 ft. tall tower• 5 story parking garage• Building was designed with a tuned mass

d e t t l l te l ele tidamper to control lateral accelerations

Passive Control System



Random House: TLCD

• Tuned Liquid Column Damper– Two TLCDs at the roof level (290 tons and– Two TLCDs at the roof level (290 tons and

430tons)– Large U-shaped tanks at right angles.

M i t i 550 t (0 33% f– Moving water mass is 550 tons (0.33% of building weight) in each tank.

– Cost effective. Cheaper than a pendulum TMD.

Super Sloshing DamperTokyo Dome Hotel

Shin-Yokohama Prince Hotel

Supplementary Damping System

• Dampers • Base IsolationBase Isolation• Tuned Mass Damper• Tuned Liquid Damper / Tuned Liquid

Column DamperCo u pe• Aerodynamic Shaping• Nonlinear Energy Sink

Burj Khalifa in Dubai: Aerodynamic ShapingAerodynamic Shaping

• Burj Khalifa• Burj Khalifa– Height: 825m (world’s tallest structure)– Floor: 160– Completion date: Jun 2009

• Damping system – Conceptual designs for sloshing water and water

column damper systems were developed by MotioneeringMotioneering

– Shape refinements and structural measures can keep building sway motions to acceptable levels

– Space for sloshing dampers

Wind Tunnel Testing at RWDI

• Rowan Williams Davies & Irwin – Ontario, Canadal l i d l• 1:500 Scale Aero-elastic Model

• Structural damping ratio of 1.5% for sway modes 1 and 2• Mounted on turntable • 36 wind directions at 10

d i t ldegree interval• Wind speeds between 0.5

and 1 3 times of the 50and 1.3 times of the 50 year design wind speed

Wind Tunnel Testing at RWDI

Disorganized Vortex Sheddingover the height of the towerover the height of the tower

Comparison of Wind Tunnel Results Wind EngineeringWind Engineering

Wind Tunnel #1 Results Wind Tunnel #3 Results

Supplementary Damping System

• Dampers • Base IsolationBase Isolation• Tuned Mass Damper• Tuned Liquid Damper / Tuned Liquid

Column DamperCo u pe• Aerodynamic Shaping• Nonlinear Energy Sink

Nonlinear Energy Sink (NES)

• A typical NES consists of a mass t d t t t i i ceconnected to a structure via a viscous

damping element and a nonlinear spring

orin

g F

orc

• The NES utilizes a restoring force with an essential (non-linearizable) nonlinearity

Displacement

Res

toce

• Two forms of this are a restoring force were considered in this work: cubic

Displacement

orin

g F

orc

resoring and one-sided impact (shown at right)

Displacement

Res

to

Impact

Displacement

Test Structure• 9 Stories

• Steel Floor Plates 2.74 m (9’) x ( )1.22 m (4’) x3.8 cm (1.5”) or 44 cm (1.75”) for NES Floors

• High Strength Steel Columns

• Total Height = 5 13 m (202”)Total Height 5.13 m (202 )

• Total Weight ≈ 10900 kg (24000 lbs)lbs)

• 1st, 2nd, and 3rd natural frequencies in weak direction of 1 84 5 57in weak direction of 1.84, 5.57, and 9.36 Hz

NES Layout – Floors 8 and 9Right Side Type 1 NES

Vibro-ImpactNES

Left Side Type 1 NES

Blast Testing• Tests performed at US Army

Corps. of Engineering site in Vicksburg MSVicksburg, MS

• C4 was used as explosive in t ttests

• Cladding on side closest to bl d di ibblast was used to distribute pressure loading to the structure

• 5 Tests – 30 psi-msec(locked/unlocked), 60 psi-(locked/unlocked), 60 psimsec (locked/unlocked), and 90 psi-msec (unlocked)

Blast Testing – 1st Floor Column Strain

15030 psi-msec Test

LockedU l k d

60090 psi-msec Test

Unlocked

100

-str

ain)

Unlocked

400

-str

ain)

50

tra

in (

mic

ro-

200

tra

in (

mic

ro-

-50

0

r C

olu

mn

St

-200

0

r C

olu

mn

St

-100

50

1st

Flo

o

-400

00

1st

Flo

o

0 10 20 30-150

Time (sec)

0 10 20 30

-600

Time (sec)

Time (sec) Time (sec)

Blast Testing – Wavelet of 7th Floor AccelerationAcceleration

30 psi-msec Test - NESs Unlocked30

eq (

Hz)

15

20

25

Fre

2 4 6 8 10 12 14 16 18 200

5

10

Time2 4 6 8 10 12 14 16 18 20

30 psi-msec Test - NESs Locked

2

30

Fre

q (H

z)

15

20

25

F

2 4 6 8 10 12 14 16 180

5

10

Time

Houston…. we’ve had a problem….

Active Control Systems


Control Actuators FeedbackLi k

FeedforwardLi k LinkLink

Computer SensorsSensors

Active Control Systems uActive Control Systems

Consider the SDOF system

mu

x

( ) ( ) ( ) ( ) ( )mx t cx t kx t bu t w tγ+ + = +&& &

Consider the SDOF systemc,k

w1 2 3u g x g x g w= − − −&

with linear state feedback / feedforward

Thus, the closed-loop dynamics are( ) [ ] ( ) [ ] ( ) [ ] ( )mx t c bg x t k bg x t bg w tγ+ + + + =&& &

The closed-loop stiffness, damping, and load factor

2 1 3( ) [ ] ( ) [ ] ( ) [ ] ( )mx t c bg x t k bg x t bg w tγ+ + + + = −

may be arbitrarily assigned

Active Control Systemsct e Co t o Syste s

ActuatorActuator Sensors

M

Actuator Sensor

M

Sensor

M

m

Actuator

M

A ti B I l ti Active BracingActive Mass Damper Active Base Isolation Active BracingActive Mass Damper

Control ComputerControl Computer

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

)(act tz

)(a3 tz&&

Control Computer/DSP Board)(t&&

)(a2 tz&&

DSP Board)(a1 tz

)(tz&& )(g tz

Kyobashi Seiwa Building (1989)

AMD-1AMD-1

AMD-2Control

Sensor

Control Computer

Sensor

Sensor

Rainbow Bridge Tower (1991)

Yokohama Landmark Tower (1993): AMD(1993): AMD

Hybrid Mass Damper

ORC200 at Osaka

Floor count: 50, Basement floor: 2Made with SRC and S2 ×100 ton

Heathrow AirportNew Control Tower

~2007 completed

Even small wind-induced vibration needs to be suppressed

Two AMD were installed at the top of the tower.

Hybrid Mass Dampers for Tower(Incheon Int’l Airport)(Incheon Int l Airport)

Ai T ffi C t l T 100 4Ai T ffi C t l T 100 4

x

yAir Traffic Control Tower: 100. 4 mAir Traffic Control Tower: 100. 4 mNatural Frequency: 0.71 HzNatural Frequency: 0.71 Hz

HMD1 HMD2

Location of HMDs: 19th Floor Hybrid Mass Damper (HMD)

0 .0 5

0 .1 0

/s2 )

0 .0 5

0 .1 0

/s)

(80 m above ground) Hybrid Mass Damper (HMD)

2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0-0 .1 0

-0 .0 5

0 .0 0

Acc

eler

atio

n (m

/

T M Dm o d e U n c o n tro lle d

2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0-0 .1 0

-0 .0 5

0 .0 0

Acc

eler

atio

n (m

/

C o n tro l le d b yH M D m o d e

2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0

T im e (se c )2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0

T im e (se c )

Signal w/o HMD Signal w/ HMD

Shanghai World Financial Center: HMD• Active tuned mass damper

Two dampers on the 90th floor– Two dampers on the 90th floor. – Sensors are used to measure the building

sway with a computer to controlsway with a computer to control

• Shapep– The Hole in the building reduces vortex-

shedding induced force.

Harumi Island Triton Square

N t St

S t d i t t i ff ti l

Next Steps …

• Smart damping strategies can effectively address a number of these challenges –devices are low power, fail-safe.

• Studies show that smart dampers can i ll hi h j i f hpotentially achieve the majority of the

performance of fully active systems.

Smart (Semiactive) Control SystemsSmart (Semiactive) Control Systems


PED

Control Actuators

Sensors SensorsComputer

Smart Damping?

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

KK--BuildingBuildingKK BuildingBuilding

172 m, 38 story

Hybrid mass damper 2

Semi-activehydraulic

dampe 88damper 88

RR--BuildingBuildingRR BuildingBuilding238.05m, 54 story238.05m, 54 story

356 356 semisemi activeactivesemisemi--activeactivehydraulic hydraulic dampersdampersdampersdampers

Smart Base Isolated Building gUsing Variable-Orifice Dampers

at Keio Universityat Keio University

Smart Bridge in Oklahoma

Variable Orifice DamperVariable Orifice DamperVariable Orifice DamperVariable Orifice Damper

SAVASAVA--IIIISAVASAVA IIII

Magnetorheological Fluid Damper

Magnetic ChokeMagnetic ChokeMR FluidMR Fluid

Magnetic ChokeMagnetic Choke

x

FF

Magnetorheological Fluids

Magnetorheological Fluids

Wh t th ?• Micron-sized, polarizable, iron particles in oilWhat are they?

What do they do?• Newtonian in the absence of applied fieldNewtonian in the absence of applied field• Develop yield strength when field applied

γηττ &+= )(u• Bingham Model: • Provide reliable means for a low-power,

rapid response interface between electronic controls and mechanical devices

Magnetorheological Fluid Damper

Magnetic ChokeMagnetic ChokeMR FluidMR Fluid

Magnetic ChokeMagnetic Choke

x

FF

xcxuF && += )sgn()(μ)(uμ

FxxcxuF p+= )sgn()(μ

c

Fx ,

pc

Force - Velocity Envelope for MR Fluid DamperMR Fluid Damper

Large force at small or zero

Maximum currentExtension

Large force at small or zerovelocity is possible

FConstant current operating curve

Zero current

Any arbitrary curve withinoperational envelope is possible

x&

xcxuF p && += )sgn()(μCompression

Applications

WindSeismic

Large-Scale Devices

Seismic Protection

3-Story Scale-Model Building

2ax&&

3ax&&

CurrentDriver

1ax&&

gx&&

dxf ,Annular Orifice

ControlComputer

Rheonetic SD-1000 H i ht 158Rheonetic SD 1000MR Damper Height: 158 cm

Mass: 304 kg

Responses due to 120% El Centro EarthquakeEarthquake

3-Story Scale-Model Building

2ax&&

3ax&&

CurrentDriver

1ax&&

gx&&

dxf ,

Measured Response• 75% reduction in peak displacements• 50% reduction in peak accelerations

ControlComputer

Rheonetic SD-1000 H i ht 158 • 50% reduction in peak accelerations• 30% better response reduction than when

device is operated in passive capacity

Rheonetic SD 1000MR Damper Height: 158 cm

Mass: 304 kg

Smart Base Isolation

MR Damper

gx&& g

Smart Base Isolation

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

22

11

====

ζζ

ff

%5.3Hz),(3.88Hz65.11 22 ζf

Response to Strong Earthquake

00.20.4

c. [g

]

Max: 0.2g

-0.4-0.2

0

0 2 4 6 8 10

Acc (0.44g for full scale)

Without damper

0 10.15[g

]

0 6 8 0 p

Optimal passive(constant voltage)

S t d i

Input Motion (El Centro NS)

-0.050

0.050.1

eler

atio

n Smart damping

28 % reduction (Peak)

-0.15-0.1

0 2 4 6 8 10

Acc

e ( )29 % reduction (RMS)

Structural Acceleration

46 % reduction (Peak)46 % reduction (Peak)59 % reduction (RMS)

Response to Moderate Earthquake

00.05

0.1c.

[g]

Max: 0.07g

-0.1-0.05

0

0 2 4 6 8 10

Acc

Without damper

(0.15g for full scale)

0.04[g]

0 2 4 6 8 10 p

Optimal passive(constant voltage)

S t d i

Input Motion (El Centro NS)

-0 02

00.02

eler

atio

n Smart damping

49 % increase (Peak)

-0.04-0.02

0 2 4 6 8 10

Acc

e ( )49 % increase (RMS)

Structural Acceleration

37 % reduction (Peak)37 % reduction (Peak)49 % reduction (RMS)

Question?

Can these devices be made largeenough for civil engineering

li i ?applications?

Prototype 20-Ton MR Fluid Damper

Thermal ExpansionThermal ExpansionAccumulator

MR Fluid

3-Stage Piston WireCoils

LORDRheoneticTM Seismic DamperMR-9000

Diameter: 20 cmSStroke: 16 cmPower: < 50 watts, 22 volts

Prototype 20-Ton MR Fluid Damper

LORDRheoneticTM Seismic DamperMR-9000

Diameter: 20 cmSStroke: 16 cmPower: < 50 watts, 22 volts

Performance Testing at theUniversity of Notre DameUniversity of Notre Dame

Performance Testing

Maximum Current

0.5 A

2 A

1 A

Zero Current 0 A

orce

(kN

)Fo

Displacement (cm)Velocity (cm/s)

Experimental Setup Measured ResponseTriangular Displacement

MR Dampers in a Building

Nihon-Kagaku-Miraikan, Tokyo

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

built by Sanwa Tekki using Lord y gMR fluid are installed between 3rd and 5th floors

Base Isolation Implementation

Tider MRD-160-100 in JZ20-2NW Offshore Platform (China)JZ20 2NW Offshore Platform (China)

Control of Stay Cable Vibration

Stay cables are prone to vibrate

Damping of stay cables is as low as δ = 0 001 0 010as low as δ = 0.001 – 0.010

ζ = 0.02% - 0.2%

0.1rem

ent)

0.3

(after Prof.

ng (L

og. D

ec

(Yamaguchi)

0.01

Moda

l Dam

pin

0.001

M

0.0010.5 1

Natural Frequency (Hz)

5


Existing solutions:Standard • Cable restrainers which tie

together cables• Altered surface roughness on

Solution

• Altered surface roughness on cables

Dampers

• Augment damping through

Bridge Deck

discrete viscous dampers attached transverse to cable

Typical Installation

However, limited damping can However, limited damping can be added to the cable!be added to the cable!

Modal Damping with Passive Damper

optimal damper exists

mpi

ng

optimal damper exists

mod

al d

amrm

aliz

ed m

strong damper locks down

weak damper provides little

no

locks down the cable

provides little damping

viscous damper coefficient

Dongting Bridge, Hunan, China

MR Damper Installation

Full Installation

Java-Powered Simulation for Base Isolationunder “Education” at http://sstl.cee.uiuc.cedu/p

Java-Powered Simulation for Base Isolationunder “Education” at http://sstl.cee.illinois.cedu/p

Conclusions

• Various types of control technologies are tl b i d t iti t ib ti fcurrently being used to mitigate vibration of

civil infrastructure• Best approach is application dependent.

C l h l ll f h d i f• Control technology allows for the design of structures with improved serviceability and safety.

current practice and future trendscurrent practice and...

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