From theory to practice: FRP STRENGTHENING OF THE STE-ÉMÉLIE BRIDGE Pierre Labossière, ing. Ph.D....

From theory to practice:FRP STRENGTHENING

OF THE STE-ÉMÉLIE BRIDGE

From theory to practice:FRP STRENGTHENING

OF THE STE-ÉMÉLIE BRIDGE

Pierre Labossière, ing. Ph.D.

Professeur

Département de génie civil

Département de génie civil, Université de Sherbrooke

FRP Strengthening of the Ste-Émélie Bridge


Outline

– FRPs for the structural engineer– Ste-Émélie de l'Énergie Bridge

– Bridge description– Research program– FRP strengthening of the bridge– Bridge testing– Budgetary considerations– Instrumentation– Remarks

– Conclusion


FRPs for the structural engineer

– Fibre reinforced polymers



– Stress-strain curves

f

frpu

frpu

E frp

Fibre (glass or carbon)

Matrix (epoxy or vinylester)

Strain

Str

ess



– Interest of the Ministère des Transports du Québec (MTQ)

– Live load rating factor LLRF = ( C1R – C2D) / C3L

– LLRF › 1 QS 660 satisfied– 0.85 ‹ LLRF ‹ 1 Legal load acceptable

– Forbidden to overloaded trucks

– Reinforcement recommended

– LLRF ‹ 0.85 Legal load excessive– Reduced maximum load posted

– Reinforcement compulsory




– Strengthen bridges for which LLRF < 0.85

LLRF Number of bridges Average age

(yrs.)

non-evaluated 986 39

> 1 198 46

from 0.85 to 1 105 51

< 0.85 223 52

1512 42



– Interest of the Ministère des Transports du Québec (MTQ)– Observation

– Bridge condition directly related to its LLRF – Bridge in good condition FCS – Bridge in poor condition FCS

– Search for a demonstration project– Identify a bridge in need of reinforcement (FCS < 1),

representative of a large number of existing bridges, and with a concrete surface condition that would allow easy installation of FRPs




– Evaluate FRPs as strengthening method

– Aim at 33 % of cost of new construction– Accessibility to majority of contractors– Minimal technical training for

installation/supervision– Design methods available to design engineers


Ste-Émélie de l'Énergie Bridge

– Bridge description– Location :Sainte-Émélie-de-l’Énergie, QC– Original construction : 1951– Length: 21.3 m (70 ft.)– Total width : 11.2 m; 2 traffic lanes : 9.1 m wide – Original design load - H20 truck load– New design load - QS660, CSA Standard S6-88

– Need to increase flexural capacity by 35%– Need to increase shear capacity by 20%



2 743457

1 52

4

11 2

00

9 14

4

21 336



– Research program– Laboratory testing of various strengthening

schemes Rectangular beams

– 105 x 350 mm; length = 3.0 m T-beams

1:3 scale model of section; length = 6.5 m

– Durability assessment Freeze-thaw cycles Wet-dry cycles Small-scale beam specimens (1.1 m long)



– Research program




900 mm

500

mm

65 mm

150 mm

5-20M




CL

33652635

14 @ 200 2 @ 305

Stirrups : = 4.76 mm



– Strengthening for bending and shear



– Design methods

Stresses

fc

fs

f’ca

Ts

Cc

bw

h d

Section

ffrp Tfrpfrp

cc

s

Strains

bi

si

ci

Csf ’sd’



– Design methods

cf sf frp



– Design methods– Strengthening for shear

Le



– Design methods CSA S6-00 (2000): Canadian Highway Bridge Design Code.

(Chapitre 16 – Fibre Reinforced Structures.) CSA S806-01: Design and Construction of Building

Components with Fibre Reinforced Polymers, en préparation. ISIS-M03-01 (2001): Reinforcing Concrete Structures with

Fibre Reinforced Polymers. ACI 440-F: Guide for the Design and Construction of

Externally Bonded FRP Systems for Strengthening Concrete Structures, draft document 2000.

Europe: Design Guidance for Strengthening Concrete Structures Using Fibre Composite Materials



Beam T2 (Replark - 6 c.)Beam T2 (Replark - 6 c.)



– Research description



Beam T3 (Carbodur)Beam T3 (Carbodur)



– Test results



– Design methods



– FRP strengthening of the bridge

710

3124

3980

710

4506

5363

2520

1094

2741

3475

4473

0

1000

2000

3000

4000

5000

6000

0 2000 4000 6000 8000 10000 12000

Position p/r au centre de l'appui (mm)

Mom

ent

(kN

.m)

Mf QS-660

Mr avant renf.

Mr après renf.

Position with respect to centre of support (mm)

Before reinforcement

After reinforcement




873757

656590 557

640

1043

874

739673

0

200

400

600

800

1000

1200

0 2000 4000 6000 8000 10000 12000

Position p/r au centre de l'appui (mm)

Eff

ort

tran

chan

t (k

N)

Vf QS-660

Vr avant renf.

Vr après renf.

Before reinforcement

After reinforcement

Position with respect to centre of support (mm)



– FRP strengthening of the bridge– Two options considered in Call for Tenders– Rehabilitation scheme :

Flexural strengthening 6 SIKA Carbodur S614 strips, 20.4 m long and 60 mm-

wide, per beam Total length of reinforcement for bridge = 490 m

Shear strengthening External GFRP stirrups with variable spacing 52 sq.metres of SikaWrap Hex 100G per beam



– Schedule Site preparation, platform installation: Sept. 8-9 Installation of gauges on existing steel reinforcement: Sept 10-11 Loading test: Sept. 14 Repair of concrete (sandblasting, mortar): Sept. 15 - Oct. 2 FRP, westbound side, flexural: Sept. 28 - 29 FRP, westbound side, shear: Sept. 30 - Oct. 1 FRP, eastbound side, flexural: Oct. 6 -7 FRP, eastbound side, shear: Oct. 7-8 Installation of fibre optic sensors on strengthened structure: Oct. 8 - 13 Loading test: Oct. 14 Completion of repairwork: Oct. 16



– Budget breakdown

Initial cost estimate ($96,000) Bid retained (on invitation) ($97,950)

Repairwork contracted out $ 104,000 (supplementary repairs)Extras $ 3,000 (sandblast + repair of supports)Protective coating not included in specs. $ 1,500

Total$ 108,500

Load testing $5,000



– Budget breakdown

Total cost : $108,500 450 $/m2

about 40-50 % of the cost of new construction



– Bridge testing– Three series of tests

before the repairwork just after the repairwork one year after the repairwork

– Objectives of the tests evaluation of the general behaviour of the bridge evaluation of stiffness increase validation of the fibre optic sensors



– Bridge testing– Three 4-axle, 33-ton trucks– Load configurations :

Static loading :– 9 loading configurations (one truck on line A, one truck

on line B, etc…)– 8 stopping positions for each loading configuration

Dynamic loading :– convoy of 3 trucks, braking on the bridge



– Bridge testing1 2 3 4 6 7 8

5

A

B

C

D

A1 (Truck 2) A4 (Truck 1)

C4 (Truck 3)



Str

ain

(x 1

0-6)

J111 before reinf.J111 after reinf.

Mid

-spa

n de

flect

ion

(mm

)

D2 before reinf.D2 after reinf.



– Instrumentation– Electric gauges

8 gauges on existing rebars, installed by MTQ 20 gauges on FRPs

– Fibre optic sensors 8 Fabry-Perot 20 Bragg

– Thermocouples 10 - to evaluate effect of temperature on gauges

– Positions of fibres and gauges determined for comparison purposes



12

34

56

78

9

10

11

12

13, 14, 15

CL

16, 17, 18

19, 20, 21

22, 23, 24

14

13

1517

16

1820

19

2123

22

24



– Long-term monitoring– Periodic readings:

electrical strain gauges, fibre optic sensors and thermocouples

approximately 1 series every 6-weeks

– Continuous readings: Fabry-Pérot sensors and external temperature 6 periods, each varying from 5 to 14 days



– Long-term monitoring

5

10

15

20

25

30

Time (hours)

Tem

per

atu

re (

oC

)

-10

0

10

20

30

40

50

60

70S

trai

n

F17

F14




4850

4900

4950

5000

5050

5100

5150

5200

5250

-30 -20 -10 0 10 20 30 40

Temperature

Me

as

ure

d S

tra

ins

Strain = 6.7 T (oC) + 5004




-15

-10

-5

0

5

10

15

20

25

30

fév.

99

mai

99

aoû

t 99

oct

. 99

jan

v. 0

0

juil

l. 0

0

oct

-00

no

v-00

jan

v-01

avr-

01

juil

-01

juil

-01

jan

v-02

juin

-02

Te

mp

era

ture

-250

-200

-150

-100

-50

0

50

100

150

200

Str

ain

Temperature Measured Residual



– Conclusions– Repairwork

Repair of concrete surface was more difficult than anticipated

Installation of flexural FRP reinforcement was relatively easy



– Conclusions– Repairwork

Special care was required in removing air trapped between the FRP and concrete surface for shear reinforcement, and to prevent slip during installation

It was necessary to heat the construction area for proper curing due to low temperature (October 1998)



– Conclusions– Monitoring

Readings from conventional gauges and LVDTs confirmed the anticipated behaviour of the FRP-strengthened structure under static loading

Readings of the fibre optic sensors are comparable with those of the conventional gauges


Acknowledgements

– Ministère des Transports du Québec– Gérard Desgagné, Guy Richard

– ISIS Canada– Department of Civil Engineering,

University of Sherbrooke– Prof. K.W. Neale– Marc Demers, Pierre Rochette– Laurent Thibodeau, Claude Aubé– Philippe Lamothe, Patrick Lapierre, Yves Beaudoin,

Patrice Pouliot, Éric St-Georges, Derek Tardif


Université de SherbrookePedestrian Bridge

– Entrance of the Faculty of Engineering– Design Competition for Students

– ISIS Canada

– Five Submissions– Queen's University– Université de Sherbrooke– University of Waterloo– University of Manitoba– University of Alberta



– Objectives of the Design Competition To illustrate ISIS technologies

– FRP reinforcement– Fibre optic monitoring

Strain sensors, temperature probes, accelerometer, web camera

Data available on-line over a web site

To provide a real practical experience to ISIS Canada students



2002 ISIS Student Design Competition

Winning entry by a team of Queen’s University

Reinforced concrete

girders and slab reinforced with

FRP rebars

Rigid frame(square HSS)Steel deck Concrete cover


3 Exposure sites :•Sherbrooke•Tsukuba, Okinawa (Japan)

Specimens :

•Sheets, plates, laminates, epoxy plates

•FRP-Confined concrete cylindres

•Beams externally reinforced with FRPs

Project began in 1997.

Exposure to continue until 2007

Correlation with accelerated ageing conditions under development

Durability of FRPs


Immersion conditions :

• Freshwater at 4C, 21C and 38C• Saltwater at 21C

Exposure: 10 000 hrs

Specimens :

• Mitsubishi Replark

• Tyfo SEH51

Measurement of

• Water absorption - gain in weight

• Tensile strength

Durability of FRPs


Durability of FRPs

Water absorption of composite plates

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Solution and temperature of exposure

Wei

ght

gain

aft

er 1

0 00

0 h

ours

of

imm

ersi

on (

%)

GFRP laminates

CFRP laminates

water 4°C water 21°C water 38°C saltwater 21°C


Durability of FRPs

Tensile strength of coupons

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Environmental exposure prior to tension tests

Ult

imat

e st

reng

th/u

nit

wid

th (

kN/m

m) GFRP unidirectional coupons (2 plies)

CFRP unidirectional coupons (4 plies)

10 000 hrs immersionin water, 4°C

10 000 hrs immersionin water, 21°C

10 000 hrs immersion insaltwater (4%NaCl), 21°C

10 000 hrs immersion in water, 38°C

Control specimens


Durability of FRPs

Beams reinforced with:• SIKA Carbodur• Mitsubishi Replark

Exposure cycle :

• 5-day immersion in fresh water at 21C• 2 days drying at 21C

Beams are 1060 mm long

Results up to 26 cycles

From theory to practice: FRP STRENGTHENING OF THE STE-ÉMÉLIE BRIDGE Pierre Labossière, ing. Ph.D....

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Transcript of From theory to practice: FRP STRENGTHENING OF THE STE-ÉMÉLIE BRIDGE Pierre Labossière, ing. Ph.D....