the benefits of using viscous dampers in a 42-story...

2010 Weidlinger® Associates 1

The Benefits of Using

Viscous Dampers in a

42-Story Building

7 May 2010

Chukwuma Ekwueme, PhD, SE Gary C. Hart, PhD, CE

Kingsley C. Ozegbe Can Simsir, PhD, CE

Gregg E. Brandow, PhD, CE

2010 Weidlinger® Associates

THANK YOUTHANK YOU

2

David LeeDavid Lee

Douglas TaylorDouglas TaylorTaylor Damping Devices

Viscous Damper Viscous Damper

Viscous Damper: A Weidlinger Project Viscous Damper: A Weidlinger Project


1971 : Marshall Lew Start of a Great Career & 1971 : Marshall Lew Start of a Great Career &

Modern Earthquake Design of BuildingsModern Earthquake Design of Buildings

9


Earthquake Shaking Potential for Southern CaliforniaEarthquake Shaking Potential for Southern California

Source: California Department of Conservation, California Geological Survey


Areas shaded in pink have an acceleration of 75%g or higher

Source: U.S. Department of the Interior - U.S. Geological Survey

MCE Ground Motion for 1.0 Sec Spectral AccelerationMCE Ground Motion for 1.0 Sec Spectral Acceleration


“Passive energy dissipation is

an emerging technology that

enhances the performance of

buildings by adding damping

to buildings.”(ASCE/SEI 41-06, pg 280)


“Passive energy dissipation is

an emerging technologyemerging technology that

enhances the performance of

buildings by adding damping

to buildings.”(ASCE/SEI 41-06, pg 280)


In the Last Century in Southern CaliforniaIn the Last Century in Southern California

16

DateDate # of # of

IsolatorsIsolatorsProject / CommentsProject / Comments

19961996 1616 Kaiser Corona w/ base isolatorsKaiser Corona w/ base isolators

19961996 186186 Arrowhead Regional Medical Center w/ base isolatorsArrowhead Regional Medical Center w/ base isolators

19971997 22 Studio Parking Garage, control seismic movementStudio Parking Garage, control seismic movement

19971997 66 Rockwell Bldg 505, control seismic movementRockwell Bldg 505, control seismic movement

19981998 8484 UCLA Knudsen Hall, concreteUCLA Knudsen Hall, concrete

19991999 3232 Nethercutt Collection, Auto MuseumNethercutt Collection, Auto Museum

19991999 6868 LA City Hall, w/ base isolatorsLA City Hall, w/ base isolators


Arrowhead Medical Center


“The forces and deformations in the

energy dissipation devices that

develop during the Design

Earthquake should be

demonstrated to be adequate by

prototype testing in accordance

with Section 9.3.8.”

(ASCE/SEI 41-06, pg 286)


“The forces and deformations in the

energy dissipation devices that

develop during the Design

Earthquake should be

demonstrated to be adequate by demonstrated to be adequate by

prototype testingprototype testing in accordance

with Section 9.3.8.”

(ASCE/SEI 41-06, pg 286)

LATBSDC & LA City Design Criteria LATBSDC & LA City Design Criteria


OBJECTIVES

25

� Use LATBSDC Design Criteria for Buildings with

Dampers

� Eliminate shear walls and evaluate impact

� Improve typical preliminary design approach

using structural optimization theory

� Compare story drift and acceleration response

for less than 50% in 30 year earthquake


� Less displacement . . . over 50% reduction in drift in many cases

� Decreased base shear and inter-story shear, up to 40%

� Much lower “g” forces in the structure. Equipment keeps working and people are not injured

� Reduced displacements and forces can mean less steel and concrete. This offsets the damper cost and can sometimes even reduce overall cost

Why Use Viscous Dampers?Why Use Viscous Dampers?

Viscous Dampers dramatically decrease earthquake induced motion . . .

Hysteresis Loops With & Without DampersHysteresis Loops With & Without Dampers


Tuning The Viscous DampersTuning The Viscous Dampers


Tuning The Brace with DampersTuning The Brace with Dampers


Typical Plan ViewTypical Plan View

31


Building 2BD Peak Top Floor Response for 50% in 50 yr Building 2BD Peak Top Floor Response for 50% in 50 yr

32


Periods of Vibration with and without Core Shear WallsPeriods of Vibration with and without Core Shear Walls

33

With Core Shear Walls Without Core Shear Walls

Period

(seconds)Dominant Direction

Period

(seconds)Dominant Direction

1 4.01 East-West Direction 1 5.75 North-South Direction

2 3.53 North-South Direction 2 5.54 East-West Direction

3 2.12 Torsion 3 3.09 Torsion


Comparison of Maximum Story Drifts for 43Comparison of Maximum Story Drifts for 43--Year Earthquake Year Earthquake

34

0

100

200

300

400

500

0 0.001 0.002 0.003 0.004 0.005

He

igh

t (f

t)

Story Drift Ratio (in/in)

With Core

Shear Walls

Without Core

Walls

0

100

200

300

400

500

0 0.001 0.002 0.003 0.004 0.005

Height (ft)


With Core

Shear Walls

Without

Core Walls


Typical Floor Plan with Viscous Damping DevicesTypical Floor Plan with Viscous Damping Devices

35

1 2

15’-6” 19’-3” 19’-3” 19’-3” 19’-3” 15’-6”

23’-0

”23

’-0”

7’-6

”7’

-6”

23’-0

”23

’-0”

3 3.5 4 5 6

A

B

C

C.5

D

E

F

Typical Damper Location

FRAME A

FRAME F

FR

AM

E 5

FR

AM

E 2N


Building 2BNSW Beams and Columns Building 2BNSW Beams and Columns

36


EE--W InterW Inter--Story Drifts for 50% in 30 years (ASCE 7)Story Drifts for 50% in 30 years (ASCE 7)

37

0

100

200

300

400

500

0 0.001 0.002 0.003 0.004 0.005

He

igh

t (f

t)


With Core Walls

Without Core Walls (No

Dampers)

Without Core Walls

(Optimized Dampers)


Comparison of Maximum Story Drifts for a 43Comparison of Maximum Story Drifts for a 43--Year Year

Earthquake Obtained from Time History AnalysesEarthquake Obtained from Time History Analyses

38

0

100

200

300

400

500

0 0.001 0.002 0.003 0.004 0.005

He

igh

t (f

t)


No Core Walls,

No Dampers

No Core Walls,

Optimized

Dampers

0

100

200

300

400

500

0 0.001 0.002 0.003 0.004 0.005

He

igh

t (f

t)


No Core Walls,

No Dampers

No Core Walls,

Optimized

Dampers


EE--W Floor Acceleration for 50% in 30 YearsW Floor Acceleration for 50% in 30 Years

39

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0 5 10 15 20 25 30 35 40 45

Acc

ele

rati

on

(g)

Time (sec)

No Core Walls, No

Dampers

No Core Walls,

Optimized Dampers


Wind Loading on Tall BuildingsWind Loading on Tall Buildings

2010 Weidlinger®

Associates

Time History of Wind Loading Time History of Wind Loading

-1.0E+05

-5.0E+04

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05

3.0E+05

0102030405060708090

Time (second)

Be

nd

ing

Mo

me

nt (K

ip-ft)

Moment - CD

Moment - CL

M vector

CD1

020

4060

80100

120140

1600 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (Interval .029 sec)

Win

d L

oa

d (k

ips

)

Wind Lift Force, FL1 (t)

Wind Drag Force, FD2 (t)














Wind Drag Forces, FDi (t)

Wind Lift Forces, FLi (t)

CL1

-80-60

-40-20

020

4060

80100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (Interval .029 sec)

Win

d L

oa

d (k

ips

)

Wind Drag Forces, FD1 (t)

X

Y


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