use of precast members for accelerated bridge construction...

6th International Bridge Conference 1

Bijan KhaleghiConcrete Specialist

Washington State Department of TransportationBridge and structures Office

Olympia, Washington

Use of Precast Members For Accelerated Bridge Construction

in Washington State


Advantages:• Precasting Accelerates Bridge Construction • Precasting Eliminates Concrete Forming,

Casting and Curing in the Jobsite• Precasting Improves Work zone Safety

Concerns:• Seismic Design and Detailing Guidelines• Monolithic Seismic Resistant Connections• Construction Equipment and Cost• Construction Tolerances

Precast Bridges


Major Faults in Major Faults in Puget SoundPuget Sound

Seismic Design in Washington State

6

6

8 79

1520

30

25

25

30

10

Everett

Seattle

TacomaOlym

pia


KOBE NORTHRIDGE LOMA PRIETA

Year 1995 1994 1989Magnitude 6.9 6.7 7.1Peak Acceleration (a) 0.80 1.00 0.60

Depth of Rupture (km)

14.3 18.0 19.0

Duration (sec.) 11 9 8Bridge Damage($ x Millions)

$6,700 $300 $1,500

NISQUALLY20016.8

52.0

$5

0.25

10

Recent EarthquakesComparison of Seismic Events


Seismic Design

Fix Connection Double-Curvature

Fixed

Fixed

Fixed

Pinned

Moment DiagramShape

Moment Diagram

Shape

Hinge Connection Single-Curvature

EQ Force

EQ Force


SEISMIC DESIGN SEISMIC DESIGN RESPONSE SPECTRARESPONSE SPECTRA

..11

.2.2.3.3.4.4.5.5.6.6

AC

CE

LE

RA

TIO

NA

CC

EL

ER

AT

ION

PERIODPERIOD

11 22 33 44

pile supported footingpile supported footing

shaft foundationshaft foundation

(sec.)(sec.)

(g)

(g)

Spread Footing foundationSpread Footing foundation

T=2mk for SDOF

undamped free vibration.

PILE FOUNDATIONPILE FOUNDATIONSHAFT FOUNDATIONSHAFT FOUNDATION SPREAD FOOTINGSPREAD FOOTING


Key Factors in Seismic Design

Precast Girder

Semi Integral End Pier

Backfill

Precast Girder

Expansion joint

Elastomeric Bearing pad

Seat width for seismic movement

Girder stop to restrain transverse movement Gap for

seismic movement

L-shape

Abutment

Ductile Connection

Joint-less Superstructure

CIP Slab

Shaft

In-Span Hinge

Pile-to-pile cap Connection


Seismic Design at Intermediate Piers(C-I-P or Precast)

Seismic Elastic Forces

ME/VE

ME/VE

ME/VE

ME/VE

ME/VE

ME/VE

Center of Mass

1.3MP/VP

1.3MP/VP

1.3MP/VP

1.3MP/VP

1.3MP/VP

1.3MP/VP

Plastic Hinging Forces

MDesign = ME/R

Response Spectrum Analysis


Fixed Intermediate DiaphragmCL Column and Diaphragm

Extended Strands for M+ Connection

Precast Girder

cn fbdV '38.0≤

Column Connections

Plastic Hinging

M = MP + VP h

uyvfn PfAV 75.0+=Construction Joint in Column

Precast Girderc.g. of

superstructure

yh

c

c

gs f

fAA '

145.0

−≥ρ

yh

cs f

f '12.0≥ρ

Confinement Reinforcement

Plastic Hinging

MP & VP

CIP Slab


2001 India Earthquake

Seismic Resistant Connections(Monolithic Connections)

2001 Nisqually Earthquake

Monolithic Connection, WA


Elevation

Design for ContinuityJoint less Superstructure

400 – 600 ft

Kobe, Japan (1995)


Positive Moment ConnectionStrand Anchor Detail

1"

1"1"

CL GirderPrestressed Girder

Strand Anchor or ChucksPier Cap

CIP Diaphragm

1’-6”

1”x 7”φ Anchor Plate

Bonded Strands

Strand Anchor

CL Girder

Alternate 1 or 2

Alternate 3


MC = Lesser elastic or plastic hinging moment of column, ft-kipsMSIDL= Moment due to traffic barriers and sidewalk, ft-kipsVC = Lesser of elastic or plastic hinging shear of column, kipsh = Distance from top of column to centroid of superstructure, ftd = Distance from top of slab to centroid of extended strands, inNC = Number of columns in the pierNg = Number of prestressed girders in the pier APS = Area of each extended strands, in2

fPS = Ultimate strength of prestressing strands, ksik = Span coefficient (k=0.5 for L1 = L2, k = 0.67 for L1 = 2L2)

xdxfAkx

NNMxhVMN

PSPSg

CSIDLCCPS 9.0

)(12 −+=

Extended Strands (Fixed intermediate Diaphragm)


Extended Strands for Positive Moment Connection(Fixed intermediate Diaphragms)

Type of GirderNumber of girders, NgColumn diameter (ft)Number of columns, Ncplastic hinging moment, MPColumn plastic shear, VpColumn Elastic moment, ME Column EQ Elastic shear, VETop of column to c.g. of superstSIDL Moment per girderTop of slab to c.g. of strandsArea of each strand, ANumber of extended strandsStrand Extension Alternative

SE 8th I/CW58G

461

96301067

124201333

817862

0.15312

3

Methow RiverW83G

752

6250887

16110

227011.821090

0.2176

1 or 2

Precast Girder ProjectsHPC

ShowcaseW74G

542

4840494

8240

5678.167194

80.750.217

51 or 2

W74G542

4920

4658060

7629.16720475

0.2176

1 or 2

Bone River

Jenkins Creek W74G

93.53

3660

3436280

5719.16718875

0.2174

1 or 2


WSDOT Standard Prestressed Girders

W50G W58GW42G W74G

2’-1”

3’-7”

6’-1

1/2 ”

2’-1” 2’-1”

4’-1

0”

1’-8”2’-1”

4’-2

”1’-8”

1’-3”3’

-6”

NSCHSC

70 90 110 13080 100 125 145

Span Capability (ft) 1995

80% of All New Bridges are Precast Girders


STANDARD WIDE FLANGE GIRDERS

W95G W83G

WF74GWF42G

3’-2”

4’-1”

WF50G WF58G

Span Capability, ftWF42GWF50GWF58GWF74G

125140165

110

W83GW95G

180190


WF42G vs. W42G

40

60

80

100

4 6 8 10 12 14 16Girder Spacing (ft)

Span

Len

gth

(ft)

WF42G

W42G

WF58G vs. W58G

60

80

100

120

140

4 6 8 10 12 14 16

Girder Spacing (ft)

Spa

n Le

ngth

(ft)

WF58G

W58G

WF74G vs. W74G

80

100

120

140

160

4 6 8 10 12 14 16Girder Spacing (ft)

Spa

n Le

ngth

(ft)

WF74G

W74GSpan Capability

Comparison


Bridge Superstructure ReplacementGirder Efficiency

Existing Bridge (1992 Design)15 – W74G Girders

New Bridge (2003 Design)8 – WF74G Girders

• fc = 10.0 ksi• fci = 7.5 ksi• 0.6” φ Strands

• fc = 6.0 ksi• fci = 5.0 ksi• 0.5” φ Strands


WSDOT TRAPEZOIDAL TUB GIRDERS1'-6"

4½"

SYMM. ABOUT ¢ TUB GIRDER

TRAPEZOIDAL TUB SECTION

71

Span Capability, ft

U54G4

U66G4U78G4UF60G4

155170150

130

UF72G4UF84G4

165185


STANDARD SPLICED I-GIRDERS

W95PTGWF74PTG W83PTG

4'-2¾“

1.020 (3'-4 3/8“)

7 7/8”

Span Capability, ft

WF74PTGW83PTGW95PTG

185 205200 235

165 180GIRDER PT Before PT After

PCI Award


Precast HSC Spliced I-Girders(Riverside Bridge)

Precast SuperstructureHinge Connections at Piers

PCI Award


STANDARD HSC SPLICED U-GIRDERS

TRAPEZOIDAL TUB SECTION

SYMM. ABOUT ¢ TUB GIRDER

VARIES 4'-0" TO 10'-0"

7

1

10"

VA

RIE

S 2'

-6"

TO

6'-6

"

4½"

1'-6"

Span Capability, ftU54PTG6U66PTG6U78PTG6

165190

145

PCI Award


Precast Spliced Girder- Fixed Diaphragm

S. 38th Street Bridge


Precast Stay-in-Place Deck Panel

S. 38th Street Bridge


Precast Spliced Girder- Fixed Diaphragm

(Green River Bridge)Precast SuperstructureHinge Connections at Piers


YES NO

Num

ber o

f Sta

tes 25 –

20 –

15 –

10 –

5 –

0 –

22 (82%)

5 (18%)

DomesticYES NO

Num

ber o

f Cou

ntrie

s

10 –

8 –

6 –

4 –

2 –

0 –

6 (100%)

0 (0%)

Foreign

PCI Seismic Design Survey

SURVEY: Use of Precast Members in Bridge Construction

Superstructure:


YES NO

Num

ber o

f Sta

tes 25 –

20 –

15 –

10 –

5 –

0 –

19 (76%)

6 (24%)

DomesticYES NO

Num

ber o

f Cou

ntrie

s

10 –

8 –

6 –

4 –

2 –

0 –

2 (33%)

4 (67%)

Foreign

Substructure:

SURVEY: Use of Precast Members in Bridge Construction

PCI Seismic Design Survey


• Lack of Design and Detailing Guidelines• Availability of Construction equipments• Lack of construction specifications • Long-term performance & maintenance concerns• Connection Details Meeting Seismic Requirements• Cost competitive with C-I-P • Cost of Fabrication and Shipping • Site and Soil Condition for Crane Load, etc• Need for Small Demonstration Projects

Difficulties in using Precast BridgesPCI Seismic Design Subcommittee Survey


Precast SubstructuresPCI Seismic Design Subcommittee

State of the Practice Repost outlines1. Introduction 2. Seismic Criteria 3. Seismic Analysis 4. Structural System Considerations5. Connection Details6. Current Practice7. Good detailing practices 8. Design Examples 9. Applicable Current Research

6th International Bridge Conference 30Precast Column

Precast Column

Precast Column Erection Support

Column reinforcement

Precast Girders

Precast Column

Cast-In-Place Shaft

Cast-In-Place Bent Cap

Confinement Zones

Construction Joint


Precast Column on Shaft


Precast Column on Spread Footing


CIP superstructure

CIP Footing

Support Pad

Precast Column



Precast Slanted Column on Spread Footing


Precast Slanted Column on Spread Footing


Reduced Scale Test Specimen

Column Test for Seismic (UNR)


Precast ColumnCompleted Precast System with monolithic connections

Section A

Plan (Precast Bent Cap) Precast Column



Seat for Precast Bent Cap (12” Min)

Joint reinforcement

A

Precast System (monolithic connections)


Cast-in-place Diaphragm

Cast-in-place Slab

Support Pad

Precast Column

Precast Bent Cap

Confinement Zones

Precast Column

Cast-In-Place Shaft

3” thick

Rubber Pad

Precast System (monolithic connections)


Precast Column

Cast-In-PlaceShaft

Cast-in-place Diaphragm

Support Pad

Precast Column

Precast Bent CapConfinement

Zones

Cast-in-place Slab

3” thick

Rubber Pad

Precast System –Precast Deck (monolithic connections)


Numerical Application (Precast column to Precast Bent cap)

Bottom of Column

Top of Column

Column Diameter, ft 6 4

Axial Load, kips 1945 1869Seismic Elastic Moment, ft-kips 22530 21360

Reduced Moment, ft-kips 4506 4272

Reinforcement Ratio 1% 3.75%

Resistance Factor 0.75 0.68Plastic Hinging Moment, ft-kips 8406 8390

Top of Column

6 (4 at Recess)1869

18360

3672

3.25%

0.68

7212


Ongoing Research With University of WA

6” φ Hole in Crossbeam for

1-3/8” φ –150 ksi Bar Tendons

PLANELEVATION


Inverted Precast T-BeamHole for Extended strands and #7 bars

CIP Slab

Ongoing Research With University of WA


Precast Pedestrian/Bike BridgePrecast SuperstructurePrecast ColumnFixed Connections at Piers

80’-0” 80’-0”

Precast Variable Depth Tub Precast Column

Cast-in-place Ductile joints


Conclusions - 1Precast bridges are effective system for Accelerated bridge construction.

Monolithic connections meeting seismic Design and Detailing requirements shall be considered

Extended strands in bottom flange provide positive flexural capacity to resist EQ Forces

Construction Tolerances shall be Considered

Long-term performance & maintenance concerns


Conclusions – 2Lack of Design and Detailing Guidelines

Lack of construction specifications

Availability of Construction equipments

Cost competitiveness with C-I-P Alternative

Fabrication and Shipping Cost

Site and Soil Condition for Crane Load and Placement

Need for Demonstration Projects

use of precast members for accelerated bridge construction...

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