rehabilitation of longitudinal joints in double-tee girder ... · rehabilitation of longitudinal...

1

Rehabilitation of Longitudinal Joints

in Double-Tee Girder Bridges

Rehabilitation of Longitudinal Joints in Double-Tee Girder Bridges

Presenter

Mostafa Tazarv, PhD, PE,

Assistant Prof.

Research Team

Lucas Bohn, RA

Mostafa Tazarv, PhD, PE

Nadim Wehbe, PhD, PE

South Dakota State University

2Rehabilitation of Longitudinal Joints in Double-Tee Girder Bridges

Funding Agencies and Collaborators

• South Dakota Department of Transportation.

• Mountain Plains Consortium (MPC) -

University Transportation Center (UTC).

3

Current longitudinal joint detailing

Background

Rehabilitation of Longitudinal Joints in Double-Tee Bridge Girders

1'-11"

2"2"

2"

2"2"

#4 Bars D8 Wire Mesh

@ 4" OC T&B

12" Dia. 7-wire Strands

1"

COVER6"

5"

5"

D4 Wire @ 8" OC

4

➢ The current longitudinal joint detail for connecting adjacent

double-tee bridge girders exhibits poor serviceability and

strength performance

Background


5

➢ Fiber-reinforced cementitious concrete

➢ Made with very fine aggregates in size of dust

➢ Usually with 2% volumetric steel fibers

➢ Better durability than concrete

➢ More than 22,000 psi (150 MPa) compressive strength

➢ Significantly higher tensile strength and strain capacity

Courtesy: Dr. Graybeal of FHWA

Ultra-High Performance Concrete


6

✓ 20 Rehabilitation Joint Detailing Alternatives.

✓ Testing of 13 Large-Scale Beams.

✓Detailed Finite Element Analysis.

✓ Testing of 40-ft Conventional Double-Tee Bridge.

✓Rehabilitation of the Conventional DT Bridge.

✓ Testing of Rehabilitated Bridge.

✓Recommendations.

Summary of Activities


7

Test Specimen and Setup


Load

Cell

N

W14x257 Column

S

HSS 12x6x1/2 Brace

Test Specimen

Two Double-Tee Girders40-ft Long, approx. 8-ft wide

8

Testing Procedure

1. Fatigue testing of conventional DT – 250k cycles.

2. Monotonic testing of conventional DT to crack the joint.

3. Fatigue II testing of rehabilitated DT– 500k cycles.

4. Fatigue I testing of rehabilitated DT– 100k cycles.

5. Ultimate testing of rehabilitated DT to failure.


0

10

20

30

40

50

0 1 2 3 4 5

Actu

ato

r L

oa

d,

P (

kip

s)

Time (sec)

Fatigue II Fatigue I

9

Instrumentation


SG-GA-L-28SG-GA-L-27SG-GA-L-32

ASG-GA-L-31

CSG-GA-L-19CSG-GA-L-17 CSG-GA-L-18

SG-GA-L-24SG-GA-L-23

SG - Strain Gauge

CsG - Concrete Strain Gauge

GA - Girder A

GB - Girder B

L - Longitudinal

➢ 34 Strain Gauges

➢ 14 LVDTs

➢ 4 String POTs

➢ 4 Load Cells

➢ 146-kip Actuator

10

Proposed Testing Plan

1'-6"

1'-6"

40'

Not to Scale

LMC

LMC Continuous

Joint

Filler Material Plan

1'-10"

A

5'

UHPC Pocketed

Joint

UHPC

578

"


Pocket Detailing: UHPC filled pockets reinforced

with steel bars.

Continuous Detailing: LMC filled joint reinforced

with wire-mesh.

11

Rehab after initial 200k Fatigue Testing


12

Rehab after initial 200k Fatigue Testing


13

Joint Pour w/ UHPC & LMC


14

Prior to Testing LMC Cracking


Girder A

Girder B

LMC Joint

Bridge U

ndern

eath

15

Fatigue Testing Video


16

Fatigue Results


K = 0.0029x + 103.1

95

100

105

110

115

0 100 200 300 400 500

Sti

ffn

ess

, K

(K

ip/i

n.)

Number of Cycles, N (x 1000)

Rehabilitated Specimen

Phase III, P = 21 kips

K = -0.0154x + 103.1

95

100

105

110

115

0 25 50 75 100

Sti

ffn

ess

, K

(K

ip/i

n.)


Phase IV, P = 42 kips


No stiffness degradation

after 0.5 million cycles of

AASHTO Fatigue II and 100k

cycles of AASHTO Fatigue I.

17

Ultimate Testing Video


18

Cracks and Failure Mode


19

Rehabilitated Joints at Girder Failure


Minor cracks at the edge of

Pocket and Continuous joints

at girder failure.

20

Ultimate Test Results


0

100

200

300

400

500

600

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10

Actu

ato

r L

oa

d,

P (

kN

)

Actu

ato

r L

oa

d,

P (

kip

s)

Midspan Deflection, Δ (in.)

Girder A Girder B First Cracking Peak Load Failure


Phase V

Strength I LS

Service I LS

Peak Load

P = 113.9 kips

Girder Cracking

P = 53.8 kips

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Ultimate Test Results


0

20

40

60

80

100

120

140

160

0 500 1000 1500 2000 2500

Actu

ato

r L

oa

d,

P (

kip

s)

Strain, με (microstrain)

P3-T-1 P3-T-2 P3-T-3 P3-T-4

P4-T-5 P4-T-6 P4-T-7 P4-T-8


Phase V

A

P3B P4P1 P2

SG-P4-T-6SG-P4-T-5

N

SG-P3-T-3SG-P3-T-4

SG-P4-T-7SG-P4-T-8

S

SG-P3-T-2SG-P3-T-1

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Evaluation


0.85

0.9

0.95

1

1.05

1.1

1.15

0 100 200 300 400 500

Norm

ail

ized

Sti

ffn

ess


Rehabilitated DT Continuous DT Conventional DT

Fatigue II, P = 21 kips

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

0 20 40 60 80 100

Norm

ail

ized

Sti

ffn

ess



Fatigue I, P = 42 kips

Grouted Key

38"

14" X 1" X 5"

WELD PLATE

UHPC

Pocket

1'-038

"

3"3" 318

"

#4 Bars @

4" OC T&B

D8 Wire @ 4" OC

5"

1"

COVER

Rehabilitated Detailing New Constr. Continuous Detailing

(Konrad, 2014)

Conventional Detailing

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Evaluation


Grouted Key

38"

14" X 1" X 5"

WELD PLATE

UHPC

Pocket

1'-038

"

3"3" 318

"

#4 Bars @

4" OC T&B

D8 Wire @ 4" OC

5"

1"

COVER

Rehabilitated Detailing New Constr. Continuous Detailing

(Konrad, 2014)

Conventional Detailing

0

100

200

300

400

500

600

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10

Actu

ato

r L

oad

, P

(k

N)

Actu

ato

r L

oad

, P

(k

ips)

Midspan Deflection, Δ (in.)


Strength I LS

Service I LS

Girder A

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Evaluation


Cost estimate for: 40-ft long by 30.6-ft wide double-tee

girder bridge having 8 girders and 7 long. Joints.

➢ Pocket joint rehabilitation cost is 28% of that of replacement.

➢Continuous joint rehabilitation cost is 57% of that of replacement.

Table 8-1 Rehabilitation vs. Replacement Cost for 40-ft Double-Tee Bridges

Type Item Cost

Replacement

Girder Material and Fabrication $79, 040

Girder Demolition, Removal, and Construction

$15,000

Crane Mobilization $20,000

Total $114,040

Rehabilitation Pocket Joint $31,685 (or 28% of Replacement)

Continuous Joint $64,856 (or 57% of Replacement)

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Conclusions

➢ Both pocket and continuous rehabilitation methods

are viable solutions to rehabilitate Double-Tee

bridges. Only UHPC should be used for field

applications.

➢ The pocket joint rehabilitation method is the most

cost effective solution.


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Comments/Questions


https://sites.google.com/people.unr.edu/mostafa-tazarv/research/rehab-of-dt-bridges

https://sites.google.com/people.unr.edu/mostafa-tazarv/research/rehab-of-dt-bridges

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Recommendations


G5

G6Max. 5 ft

Min. 18 in.

No more than 2 ft

Length

Min. 18 in.

B

UHPC Pocket Joint

Midspan

Min.

5.5 in. A

UHPC

(2) Cont. #4 Bars#4 Bars @

4" OC Long. & Trans.

638

"

1"Min.

3-in.

UHPC Pocket

Min.

3-in.

D8 Wire @ 4" OC

5"318

"

1"

COVER

(2)

Co

nt.

#4

Ba

rs

318

"

Min.

5.5-in.

1"5"

Min. 2.5-in.

UHPC Key

1"

COVER

Section A – Shear key Detailing Section B - Pocket Joint Detailing

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Recommendations

➢Preparation

1. 1-in. Saw-cut around perimeters.

2. Hammer-chip at 45 degree slope, 20 degrees

between pockets:

a. 30-lb chippers for first 2.5 inches.

b. 15-lb chippers around reinforcement.

3. Hydro-demolition shall be permitted as an alternative.

4. Joint surface shall be sand-blasted and pre-wetted

for 24 hours prior to pouring.

5. Formwork shall be water tight and installed from top

of bridge.


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Recommendations

➢Pocket Detailing

1. UHPC filled square pockets with minimum side

dimensions of 18 inches. Spacing shall not exceed 5

ft c/c.

2. UHPC filled continuous key with a minimum width of

5.5 inches.

3. Pockets reinforced with four Gr. 60 No. 4 bars each

direction. Continuous key reinforced with two Gr. 60

No. 4 longitudinal bars.

4. Minimum lap-splice of 3 inches between pocket

reinforcement and exposed wires.


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