The Alaskan Way Viaduct Steve Kramer University of Washington Seattle, Washington.

The Alaskan Way ViaductThe Alaskan Way Viaduct

Steve Kramer

University of Washington

Seattle, Washington

The Alaskan Way ViaductThe Alaskan Way Viaduct

Steve Kramer

University of Washington

Seattle, Washington

(The interesting stuff, not the structural stuff)

Alaskan Way ViaductAlaskan Way Viaduct

• 2.2 miles long• 86,000 vehicles per day• North of Yesler

Designed by City of Seattle

Constructed in 1950• South of Yesler

Designed by Washington State DOH

Constructed in 1956


© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping

SeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattle

Yesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler Terrace

Elliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott Bay

999999999999999999

Harborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview Hospital

U S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina Hospital

Mason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason Hospital

Union DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street Station

Seattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle University

1ST

4TH

BO

RE

N

E MADISON

RAIN

IER AVE S

S 1

ST

STEW

ART

YESLER WAY

I-5

RAMP

I-90

© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping

AWV

© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping

SeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattle

Yesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler Terrace

Elliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott Bay

999999999999999999

Harborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview Hospital

U S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina Hospital

Mason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason Hospital

Union DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street Station

Seattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle University

1ST

4THALA

SKA

N W

AY

BO

RE

N

E MADISON

RAIN

IER AVE S

S 1

ST

STEW

ART

YESLER WAY

I-5

RAMP

I-90

© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping

Seattlesection

WSDOTsection



Seattlesection

WSDOTsection


Seattle Section


WSDOT Section

Seismic Vulnerability ConcernsSeismic Vulnerability Concerns

• Loma Prieta earthquake

M=7.1

100 km south of Oakland

• Cypress Structure

Highway 17 in Oakland

Double-deck reinforced concrete structure

Similar age

Similar design requirements

Pile supported due to soft surficial soils

Cypress StructureCypress Structure

Alaskan Way Viaduct InvestigationsAlaskan Way Viaduct Investigations

• 1990 WSDOT internal review

• 1991-92 UW review

• 1993-95 UW/WSDOT investigation

• 1995-96 WSDOT seawall investigation

UW / WSDOT InvestigationUW / WSDOT Investigation

WSDOT Seawall InvestigationWSDOT Seawall Investigation

• Structural Engineering Aspects

• Geotechnical Engineering Aspects

• Seawall performance

• Effects on AWV

• Remediation strategies

Geotechnical Engineering InvestigationGeotechnical Engineering Investigation

• Site characterization

• Seismic hazard analysis

• Ground response analyses

• Foundation response characteristics

• Evaluation of liquefaction hazards

Site CharacterizationSite Characterization

• Review of historical records

• Review of previous subsurface investigations

• Supplemental subsurface investigations

SPT

CPT

Seismic cone

Downhole seismic

Seattle, 1888Seattle, 1888Historical RecordsHistorical Records

Seattle, 1884Seattle, 1884Historical RecordsHistorical Records

Lake Washington

Yesler

I-5

Looking NW fromBeacon Hill

Looking north along waterfront

Looking eastfrom Elliot Bay

Seattle Regrading ActivitiesSeattle Regrading Activities

Tideflats, 1896

Tideflat ReclamationTideflat Reclamation

Tideflat ReclamationTideflat Reclamation

Railroad Avenue - 1920sRailroad Avenue - 1920s

Seattle SeawallSeattle Seawall

• 12,000 lb/ft lateral thrust

• Four different wall types

- Timber pile-supported relieving platform (2)

- Pile-supported concrete wall

- Fill and rip rap wall

• Total cost: $1.4 million

Type B Seawall SectionType B Seawall Section

Type B Seawall SectionType B Seawall Section

Precast Section

Master Pile

Timber Relieving Platform

BatterPiles (12)

VerticalPiles (6)

Pile/Platform ConnectionPile/Platform Connection

Seawall ConstructionSeawall Construction

40

50

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

-130

-140

-150

-160

250240230220210200190180170160150140130120110100908070605040302010010203040

CL

5060708090100110120130140150160170180190200210220230240250260270280290300310320330340350360370380

60

70

1.25:1

70

60

50

40

30

-90

-100

-110

-120

-130

-140

-150

0

0788737694084927850/4"78/6"

B-7 B-2

R-3 R-4-72-72

Projected117' NW

6541/6"012114450/4"50/3"50/6"

4788/11"50/5"

758950/6"50/4"

9342

1/18"

43765

H-3-93

Projected157' NW

73

8516100+

R-16-82

Projected

55125510100+

R-17-82

Projected

DATE

SCALE VERT.

HORIZ.

SHEET OF

DRAWN BY

JOB S.R. C.S.

WASHINGTON STATE

DEPARTMENT OF TRANSPORTATION

MATERIALS BRANCHMATERIALS ENGINEER

TRANSPORTATION COMMISSION

CITY OF SEATTLE DATUM

ALASKAN WAY VIADUCT

D. C. JACKSON

1"=40'1"=40'

FEB. 1996

FILL2

22

11213281346351/6"

5160/6"84/6"

R-5-68

Projected85' SE

R-6-68

171491612114/10"65/6"

6974100/2"

Projected147' NW

Projected154' NW

H-35-96

Projected 38' SE25' SE

0

42/18"1/12"1/24"

1/60"

20

10

Hole terminateddue to

contaminated soil

MS-2494 99 1102

22' NW

?

?

?

??

TILL

TILLTILL

TILL

CPT38

VIC. BENT 97

VIADUCT STA. 86+15

200' SOUTH OF CLOF YESLER WAY

500

Qc (tsf)

WATER LINE

'

ALASKAN WAY VIADUCT1 1

LSH

FIGURE 6: SECTION E - E'

Fill and Rip Rap Wall SectionFill and Rip Rap Wall Section


• History

-Originally intended as downtown bypass

- Design began in 1948, bids opened 1949

- Seattle section opened April 4, 1953

- WSDOT section opened Sept 3, 1959

- Seneca Street off-ramp opened 1961

- Columbia Street on-ramp opened 1966

• Facts

- 7,600 ft long

- 58,867 yards of concrete, 7,460 tons of rebar

- 171,410 ft of piling

36 ft

22 ft

70 ft

Typical Elevation (WSDOT Section)Typical Elevation (WSDOT Section)

57 ft57 ft

36 ft

22 ft

47 ft

Typical Interior Bent (WSDOT Section)Typical Interior Bent (WSDOT Section)

FoundationsFoundations

WSDOT Section Seattle Section

2’

2.5’

FoundationsFoundations

Seattle Section WSDOT Section

17’

13.5’

12’

12’

3.5’

Seattle Section WSDOT Section

Originally intended to use only H-piles

Contractor requested change

Steel piles - 48 tons

All other piles - 40 tons

S. Massachusetts St.

Columbia St.University

St.

Yesler Way

S. Royal Brougham Way

Blanc

hardSubsurfaceSubsurface

DataData

Stewar

t St.

50 shallow borings by SED in 1948

17 deep borings by WSDOH in mid-1950s

Various borings by others

8 borings with SPT

16 CPT soundings with seismic cone

2 deep borings with downhole seismic

100

50

0

-50

-100

-150

Ele

vaio

n (f

t)

Ele

vatio

n (f

t)

100

0

50

-50

-100

-150

Waterfront FillTideflat Deposit

Till

1000 ft

Bla

nch

ard

Ste

war

t

Uni

vers

ity

Yes

ler

Mas

sach

use

tts

Roy

al B

roug

ham

Subsurface ProfileSubsurface Profile

0

50

100

150

0 10 20 30 40 50

Existing Data

SupplementalSubsurfaceInvestigation

Standard Penetration Resistance (blows/ft)

De

pth

(ft)

Uncorrected SPT ResistanceUncorrected SPT Resistance

Uncorrected CPT Tip ResistanceUncorrected CPT Tip ResistanceD

ep

th (

ft)

0

50

100

150

0 100 200 300 400

Cone Penetration Tip Resistance (tsf)

De

pth

Be

low

To

p o

f T

ill (

ft)

Vs (ft/sec)

0

100

150

200

250

50

0 1000 2000 3000

Shear Wave Velocity (ft/sec)

De

pth

Bel

ow

Top

of T

ill (

ft) FederalBuilding

B-1

B-2

Till StiffnessTill Stiffness

Average

-0.5

0

0.5

0 20 40 60 80

Input MotionsInput Motions

• PSHA (10% in 50 yrs = 475-year return period)- Peak acceleration- Spectral velocities- Bracketed duration

• Design-level response spectrum

• Quasi-synthetic time histories

• Deconvolution to produce 3 “bedrock” motions

Acc

eler

atio

n (g

)

Time (sec)

Ground Response AnalysisGround Response Analysis

• Equivalent linear analyses (SHAKE)

• Nonlinear, effective stress analyses (TESS, DESRA)

• Numerous soil profiles

0 20 30 40 5010

Time (sec)

0.6

0.0

-0.6

0.6

0.0

-0.6

0.6

0.0

-0.6

Acc

eler

atio

n (g

)A

ccel

erat

ion

(g)

Acc

eler

atio

n (g

)

10 ft soft soil

50 ft soft soil

100 ft soft soil

Ground Surface MotionsGround Surface Motions

0.0

Period (sec)

1.0 2.0 3.0 4.0 5.00.0

1.0

2.0

0.5

1.5

2.5

S (g)a

Ground Surface Response SpectraGround Surface Response Spectra

10 ft soft soil

50 ft soft soil

100 ft soft soil

Waterfront FillTideflat DepositTill

Waterfront Fill

Tideflat Deposit

Till

100

50

0

-50

-100

-150

Ele

va

tio

n (

ft)

1000'

Pe

ak

Ac

ce

lera

tio

n (

g)

a max

0.0

0.5

Peak AccelerationsPeak Accelerations

Liquefaction SusceptibilityLiquefaction Susceptibility

• Historical evidence

- Sand boils in 1949 and 1965

- Broken pipes in 1949 and 1965

- Lateral movements in 1965

• Construction techniques

- Hydraulic filling

- Dumping through water

• Previous investigations

- Mabey and Youd (1991)

- Grant et al. (1992)

Scenario Earthquake #1 Scenario Earthquake #2

M 7.5 7.5

a max 0.30 g 0.15 g

Displacement (in.)

>100 14 - 100

84 - 100 6 - 48

45 - 84 2 - 12

10 - 45 0 - 4

Little liquefaction susceptibility but in areas with

steep slopes. Liquefaction is unlikely, but if it

were to occur, large displacements are

possible.

No displacement likely due to liquefaction.

Mabey and Youd (1991)

0

10

20

0 5 10 15 20 25 30 35D

epth

(ft

)

(N )1 60

(N )1 60required to prevent

liquefaction

Liquefaction EvaluationLiquefaction EvaluationStandard Penetration Test

0

10

20

30

40

50

0 5 10 15 20 25 30 35

(N )1 60

Dep

th (

ft)

(N )1 60

required to prevent liquefaction

Liquefaction EvaluationLiquefaction EvaluationStandard Penetration Test

0

10

20

30

40

50

60

70

0 0.25 0.5 0.75 1 1.25

FS L

Dep

th (

ft)

SPT-Based Factor of SafetySPT-Based Factor of Safety

Dep

th (

ft)

(q )c 1

(q )c 1required to prevent

liquefaction

(tsf)

0

10

20

0 100 200 300 400 500

Liquefaction EvaluationLiquefaction EvaluationCone Penetration Test

Dep

th (

ft)

(q )c 1 (tsf)

Liquefaction EvaluationLiquefaction EvaluationCone Penetration Test

0

10

20

30

40

50

0 100 200 300 400 500

(q )c 1required to prevent

liquefaction

0

10

20

0 5 10 15 20 25 30 35D

epth

(ft

)

(N )1 60

Design-levelground motion

Liquefaction EvaluationLiquefaction EvaluationComparison with 1965 observations

Dep

th (

ft)

(N )1 60

0

10

20

0 5 10 15 20 25 30 35


1965groundmotion


0

10

20

30

40

50

0 5 10 15 20 25 30 35

(N )1 60

Dep

th (

ft)



0

10

20

30

40

50

0 5 10 15 20 25 30 35

(N )1 60

Dep

th (

ft)


1965groundmotion


0

10

20

30

40

50

60

70

0 1 2 3

FS L

De

pth

(ft)

SPT-Based Factor of SafetySPT-Based Factor of Safety

1965groundmotion

Effects of LiquefactionEffects of Liquefaction

• Sand boils - expected over most of length

• Post-earthquake settlement

- Up to 1” in fill above water table

- Up to 25” in soft, saturated soils

• Vertical pile movement

- Tip capacity reached at r = 0.6

- Tips of southernmost piles in liquefiable soil

• Lateral pile movement

- Depends on lateral soil movement

- 10”-12” expected to cause bending failure

- Lateral soil movement depends on seawall movement

u

All movements variable due to variability of soil profile

Seawall InvestigationSeawall Investigation

• Transverse profile characterization

- 5 additional borings (2 offshore)

- 3 additional CPT soundings

• Seawall structure characterization

- Member sizes

- Member properties

- Connection strengths

• Computational model

- Soil

- Seawall

- Soil-seawall interaction

Estimation of permanent deformations due to liquefaction

FLAC

FLACFLAC

Fast Lagrangian Analysis of Continua

• Explicit finite difference code• Large-strain capabilities• Several soil constitutive models• Structural elements (beams, piles, cables)• Interface elements (normal and shear)• Coupled stress-deformation and flow capabilities• Incremental construction modeling• Graphical display of results• Dynamic option• Creep option• FISH programming language

Alaskan Way Viaduct

Type B Wall ModelType B Wall Model

Entire Section

Alaskan Way Viaduct


Entire Section

3400 soil elements610 structural elements

Precast Section

Master Pile

Timber Relieving Platform

BatterPiles (12)

VerticalPiles (6)


Modeling ApproachModeling Approach

Strain

Stress

G G fi

Strain due to softening

• Primary effects of liquefaction

- Reduction of soil strength

- Reduction of soil stiffness

• Stiffness reduction approach1. Analyze with pre-liquefaction properties

2. Analyze with post-liquefaction properties

3. Subtract pre-liquefaction displacements from post-liquefaction displacements

DisplacementsDisplacements

MaximumDispl = 0.71 ft

Deformed ShapeDeformed Shape

Deformations magnified by factor of 5

Bending MomentsBending Moments

Type B WallType B Wall

Beforeliquefaction


Duringliquefaction


Afterliquefaction

Fill and Rip Rap WallFill and Rip Rap Wall

Beforeliquefaction


Duringliquefaction


Afterliquefaction

Columbia St.

Madison St.University St.

S. Washington St.

Zones of Large Lateral MovementsZones of Large Lateral Movements

The Alaskan Way Viaduct Steve Kramer University of Washington Seattle, Washington.

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