earthquake engineering and the alaskan way...

Earthquake Engineering and theEarthquake Engineering and theAlaskan Way ViaductAlaskan Way Viaduct

Steve Kramer

University of Washington

Seattle, Washington

Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage

Caused by excessive ground shakingStrongly influenced by local soil conditions

StructuralStructural

GeotechnicalGeotechnical

Caused by ground failureStrongly influenced by local soil conditions



Mexico City, 1985Low bedrock accelerationsStrong amplificationStrong ground surface motions



Loma Prieta, 1989

Modest rock accelerationsStrong amplificationStrong ground surface motions



San Fernando, 1971

Strong motionLack of transverse reinforcement

Engineering for Earthquakes

Structures


Structural Engineering Considerations

• Design of new structures

• Retrofitting of existing structures


Design Considerations

Performance objectives

Immediate Occupancy Life Safety Collapse Prevention

Immediate OccupancyImmediate Occupancy Life SafetyLife Safety

Collapse PreventionCollapse Prevention Seismic Loading on Structures

Earthquake motion

Gravity load (vertical)

Weight of structure

Weight of contents

Vertical

seismic

loads

Horizontal

seismic

loads

Seismic Loading on Structures

Earthquake motion

Seismic Loading on Structures

LengtheningShortening

Rotation

To prevent excessive movement, must restrain

rotation and/or lengthening/shortening

Types of structures

Moment frame

Strong

beam/column

connections

resist

rotation

Types of structures

Braced frameDiagonal bracing

resists lengthening

and shortening

Concrete Shear Wall

Shear wall

resists

rotation and

lenthening/

shortening

Structural Materials

MasonryVery brittle if unreinforcedCommon in older structuresCommon facing for newer structures


Timber


ConcreteHeavy, brittle by itselfDuctile with reinforcement

Rebar


SteelLight, ductileEasy connections

Structural Damage

Masonry

IranSan Francisco

Watsonville

Structural Damage

Timber

Structural Damage

Timber

Soft first floor

Reinforced Concrete Column

Structural Damage

Reinforced Concrete

Axial

Lateral

Overturning

Rebar

Structural Damage

Reinforced Concrete

Insufficient

confinement

Insufficient

confinement

Structural Damage

Reinforced Concrete

Increased

confinement

Structural Damage

SteelFractured weld


Occurs in loose, saturated sands

Grain structure collapses

Pore pressure increases

Effective stress decreases

Strength and stiffness decrease

LiquefactionLiquefaction



Niigata, 1964

LiquefactionBearing failure



Kobe, 1995

LiquefactionLateral spreading



Niigata, 1964

LiquefactionLateral spreadingPile foundation failure




Can occur due to liquefaction

Can occur in non-liquefiable soil

LandslidesLandslides



Peruvian Andes, 1970



Yungay, Peru



Yungay, Peru







Source




Source

Yungay



Yungay, Peru

Before After


Retaining Structure FailuresRetaining Structure Failures

Active pressure on back of wall increases

Passive pressure on front of wall decreases

Wall translates and/or rotates



Port of Seattle, 1965



Port of Kobe, 1995



Port of Kobe, 1995


LifelinesLifelines

GasElectrical powerWaterSewerStorm drainData

HighwaysBridgesPorts


LifelinesLifelines



Required forphysical health


LifelinesLifelines



Required forphysical health

Required foreconomic health


LifelinesLifelines

Natural Gas


LifelinesLifelines Water


LifelinesLifelines

Ports


LifelinesLifelines

Transportation

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

STE

WART

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

SKAN

WAY

BO

RE

N

E MADISON

RAIN

IER

AVE S

S 1

ST

STE

WART

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

Alaskan Way ViaductAlaskan Way Viaduct Alaskan Way ViaductAlaskan Way Viaduct


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 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

Tideflats, 1896

TideflatTideflat Reclamation Reclamation

TideflatTideflat Reclamation Reclamation Railroad Avenue - 1920sRailroad Avenue - 1920s

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

Seawall ConstructionSeawall Construction

40

50

60

30

20

10

0

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

-130

-140

-150

1601501401301201101009080706050403020100100110120130150160170180190200 210220230240250260250260270280290300310300310320330340350360 90 80 70 60 50 40 30 20 10

B-7

105/9"

1/24"

1/18"

1/40"

14

3

4

2

8

53

45

49

65

30

92/10"

97/9"

50

8

6

6

6

3

2

5

13

2

1

53/6"65/6"

4750/2"

25

H-4-93

MUDLINE

VIC. BENT 75

VIADUCT STA 70+45

SEAWALL STA. 5+30

60' S. CL SENECA

DAMES AND MOORE SAMPLER

WT.= 320 lb STROKE 30"

?

?

TILL

50/3"(ON ROCK)0

50/3"

50/5"

50/4"

B-2-81

?

WATER LINE

CITY OF SEATTLE DATUM

TILL

CL

140

H-34-96

4

8

2

0

0

50/3"

65

18

24

36

370380

?

?

DATE

SCALE VERT.

HORIZ.

SHEET OF

DRAWN BY

JOB S.R. C.S.

WASHINGTON STATE

DEPARTMENT OF TRANSPORTATION

MATERIALS BRANCHMATERIALS ENGINEER

TRANSPORTATION COMMISSION

40

50

60

30

20

10

0

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

-130

-140

-150

D. C. JACKSON

FEB. 1996

1"=40'

1"=40'

LSH

MS-2494 99 1102

ALASKAN WAY VIADUCT

ALASKAN WAY VIADUCT

FIGURE 4: SECTION C - C'

1 2

B-2, B-7 AND B-8

Type A Seawall SectionType A Seawall Section

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

0788737

69

4084927850/4"

78/6"

B-7

Boring Projected

70' South

B-2

R-3 R-4-72-72

Projected270' NW

6541/6"012114450/4"50/3"50/6"4788/11"50/5"758950/6"

50/4"

9

342

1/18"

43765

H-3-93

Projected

310' NW

73

8516100+

R-16-82

Projected 115' NW

55125510100+

R-17-82

Projected175' NW

DATE

SCALE VERT.

HORIZ.

SHEET OF

DRAWN BY

JOB S.R. C.S.

WASHINGTON STATE





ALASKAN WAY VIADUCT

D. C. JACKSON

1"=40'

1"=40'

JAN. 1996

22

112

1328134

6351/6"5160/6"84/6"

R-5-68

Projected 15' SE

171491612114/10"65/6"6974100/2"

R-6-68

Projected 300' NW

01/60"42/18"1/12"1/24"

H-35-96

Hole terminateddue to

contaminated soil? ??

??

TILL

TILL

TILL

TILL

Projected 105' NW

CPT38

VIC. BENT 96

VIADUCT STA. 85+46

30' SOUTH OF INTERSECTIONWITH CL OF YESLER WAY

MS-2494 99 1102

500

Qc (tsf)

ALASKAN WAY VIADUCT

WATER LINE

FIGURE 5: SECTION D - D'

1 1

LSH

Pile-Supported Concrete Wall SectionPile-Supported Concrete Wall Section

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

0788737

69

4084927850/4"

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"

9

342

1/18"

43765

H-3-93

Projected157' NW

73

8516100+

R-16-82

Projected

551255

10100+

R-17-82

Projected

DATE

SCALE VERT.

HORIZ.

SHEET OF

DRAWN BY

JOB S.R. C.S.

WASHINGTON STATE





ALASKAN WAY VIADUCT

D. C. JACKSON

1"=40'

1"=40'

FEB. 1996

FILL2

22

112

1328134

6351/6"

5160/6"84/6"

R-5-68

Projected

85' SE

R-6-68

171491612114/10"65/6"6974100/2"

Projected

147' 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 CL

OF 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’


Originally intended to useonly H-piles

Contractor requestedchange

Steel piles - 48 tons

All other piles - 40 tons

Originally intended to useonly H-piles

Contractor requestedchange

Steel piles - 48 tons

All other piles - 40 tons


S. Massachusetts St.

Columbia St.

University S

t.

Yesler Way

S. Royal Brougham

Way

Bla

ncha

rdSubsurfaceSubsurface

DataData

Ste

war

t St.

50 shallow borings by SEDin 1948

17 deep borings by WSDOHin mid-1950s

Various borings by others

8 borings with SPT

16 CPT soundings withseismic cone

2 deep borings with downholeseismic

100

50

0

-50

-100

-150

Ele

va

ion

(ft

)

Ele

vation (

ft)

100

0

50

-50

-100

-150

Waterfront FillTideflat Deposit

Till

1000 ft

Bla

nch

ard

Ste

wa

rt

Un

ive

rsity

Ye

sle

r

Ma

ssa

ch

use

tts

Ro

ya

l B

rou

gh

am

Subsurface ProfileSubsurface Profile

0

50

100

150

0 10 20 30 40 50

Existing Data

SupplementalSubsurfaceInvestigation

Standard Penetration Resistance (blows/ft)D

ep

th (

ft)

Uncorrected SPT ResistanceUncorrected SPT Resistance

-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

Accele

ration (

g)

Time (sec) 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

Acce

lera

tion (

g)

Acce

lera

tion (

g)

Acce

lera

tion (

g)

10 ft soft soil

50 ft soft soil

100 ft soft soil

Ground Surface MotionsGround Surface Motions

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 35

Depth

(ft)

(N )1 60

(N )1 60required to prevent

liquefaction

Liquefaction EvaluationLiquefaction Evaluation

Standard Penetration Test

0

10

20

30

40

50

0 5 10 15 20 25 30 35

(N )1 60

Depth

(ft)

(N )1 60

required to preventliquefaction

Liquefaction EvaluationLiquefaction Evaluation

Standard Penetration Test

0

10

20

30

40

50

60

70

0 0.25 0.5 0.75 1 1.25

FS L

Depth

(ft

)

SPT-Based Factor of SafetySPT-Based Factor of Safety

0

10

20

0 5 10 15 20 25 30 35

Depth

(ft)

(N )1 60

Design-levelground motion

Liquefaction EvaluationLiquefaction EvaluationComparison with 1965 observations

Depth

(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

Depth

(ft)



0

10

20

30

40

50

0 5 10 15 20 25 30 35

(N )1 60

Depth

(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)

Type B Wall ModelType B Wall Model Type B WallType B Wall

Beforeliquefaction

Type B WallType B Wall

Duringliquefaction

Type B WallType B Wall

Afterliquefaction

Fill and Rip Rap WallFill and Rip Rap Wall

Beforeliquefaction


Duringliquefaction


Afterliquefaction

Columbia St.

Madison St.

University S

t.

S. Washington St.

Zones of Large Lateral MovementsZones of Large Lateral Movements

Structural Aspects of Seismic VulnerabilityStructural Aspects of Seismic Vulnerability

• Dynamic Response Spectrum Analyses

• Nonlinear “Pushover” Analyses

• Investigated capacities and demands for:

- Flexure (beams and columns)

- Shear (beams and columns)

- Splices

- Joints

- Pile Caps

Capacity/Demand RatiosCapacity/Demand Ratios

3.12

4.35

0.62

0.49 0.56

0.69

1.96

2.15

Exterior Frame - Column Flexure


1.91

9.87

0.60

0.46 0.53

0.67

1.88

1.17

Interior Frame - Column Flexure


Longitudinal Frame - Column Flexure

3.57

0.61

0.66

1.70

1.65 3.18 2.72

1.971.58

0.71

0.92

0.43

0.50

0.43

0.50

0.69


0.02

0.10 0.12

0.03

Splices

InteriorFrame

ExteriorFrame

Pile CapsPile Caps

FlexuralCapacity - OK

Shear Capacity -Insufficient (C/D= 0.3 - 0.6)

AnchorageCapacity -Insufficient

Joint Capacity -Insufficient (C/D= 0.6 - 1.2)

Summary of Structural VulnerabilitySummary of Structural Vulnerability

• Lower-level splices highly vulnerable

• Joints highly vulnerable

• Columns - shear capacity marginal

• Footings - vulnerable to brittle failure

• Special sections require additional investigation

- Outrigger bents

- On/off ramp sections

Summary of Structural VulnerabilitySummary of Structural Vulnerability

• Lower-level splices highly vulnerable

• Joints highly vulnerable

• Columns - shear capacity marginal

• Footings - vulnerable to brittle failure

• Special sections require additional investigation

- Outrigger bents

- On/off ramp sections

Effects of liquefaction-induced lateral soilmovements will dominate effects of shaking

earthquake engineering and the alaskan way...

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