Structural Use of Fibre-Reinforced Polymer

(FRP) Composites in Construction: Past Achievements and Future Opportunities

Jin-Guang Teng 滕锦光

Chair Professor of Structural Engineering &

Director of Research Institute for Sustainable Urban Development (RISUD)

The Hong Kong Polytechnic University (PolyU)

香港理工大学

OUTLINE

• Background and history

• Strengthening of concrete structures

• Strengthening of steel structures

• FRP composites in new structures

• Concluding remarks

Span = 14 meters

By Amoorland

The First Reinforced Concrete Bridge Chazelet Bridge in France, by Joseph Monier, 1875

The first reinforced concrete building (a small two-story servant's cottage) was erected in 1854 by a plasterer, William B. Wilkinson of Newcastle-upon-Tyne, UK.

In 1824, Joseph Aspdin, from Leeds, England, patented the Portland cement; it resembled a natural stone quarried on the nearby Isle of Portland.

https://en.wikipedia.org

Corrosion in Concrete Structures

http://www.adbengineering.com/services/structural-inspections/

http://is2c.nl/project-10979/files/Corrosion_to_Rebar_of_Concrete_Pile.jpg

Fibre-Reinforced Polymer (FRP) Composites

Fibers

Resin matrix

Fiber-reinforced polymer (FRP) composites are formed by embedding continuous fibres in a polymeric resin matrix

0.0 0.5 1.0 1.5 2.0 2.5 3.00

500

1000

1500

2000

2500

3000

Mild steel

GFRP

Str

ess

(MP

a)

Strain (%)

CFRP

AFRP = Aramid FRP

BFRP = Basalt FRP

CFRP = Carbon FRP

GFRP = Glass FRP

FRP Products for Strengthening Applications

Why FRP Composites?

ADVANTAGES:

Have all the advantages of steel plates for plate bonding

Speedy application; Minimal increases in structural

weight and size.

High strength/weight ratio

Lifting equipment eliminated; Reduced labour cost.

Flexibility in shape

Can be handled in rolls; easy for wrapping on curved

surfaces and around columns.

Tailorability of material properties

Providing mechanical resistance in chosen directions

through appropriate fibre orientations and lamination

structures

High resistance to corrosion and other chemical attacks

Durable performance.

DISADVANTAGES:

High material cost

Lack of ductility

Softens quickly at high temperatures

Overall:

Cost-effective strengthening solutions

Why FRP Composites?

Ibach bridge 1991

only 6 working hours!

CFRP strips were going to be prepared

Ibach bridge 1991

First use of CFRP to strengthen a structure

13 years

0

20

40

60

80

100

120

140

160

1991 1993 1995 1997 1999 20011982 1987

firs

t id

ea

feasib

ilit

y

o.k

.

ton

s o

f C

FR

P i

n C

H

Patience, patience, patience………..

FRP Strengthening of RC Structures:

Selected Laboratory Tests

From JEC 2009 in Paris

Worldwide annual carbon fiber production in 2008: 35'000 t

Source Dr. Christophe Lanoud, R&D GE

Air- & Spacecraft

Industry

Construction

Industry

Sport

Industry

FRP Strengthening of RC StructuresExtensive Research and Design Guidance Exist

Concrete Society (2000, 2004, 2012)

fib (2001)

ISIS (2001)

JSCE (2001)

ACI 440 (2002, 2008)

Chinese National Standard (2011)

Design guidelines for externally bonded FRP reinforcement for strengthening concrete structures

Some of the Design Guidance Documents

USA UK Australia China

Extensive research is being conducted at PolyU to

improve the theory of FRP-strengthened structures

and to address deficiencies of the existing design

guidance documents

FRP IN CONCRETE STRUCTURES: GROWTH OF SCI

PAPERS

Results from a keyword search using “FRP and concrete”

in the Web of Science Core Collection conducted on 16

September 2014

OUTLINE

• Background and history

• Strengthening of concrete structures

• Strengthening of steel structures

• FRP composites in new structures

• Concluding remarks

Flexural Strengthening of Concrete Beams

FLEXURAL STRENGTHENING OF BEAMS

混凝土梁的抗弯加固

RC beam

Soffit plate

Adhesive layer

ASection A

CONVENTIONAL FAILURE MODES OF RC

BEAMS BONDED WITH AN FRP SOFFIT PLATE

常规的破坏模态

(a) FRP rupture

(b) Crushing of compressive concrete

Concrete Crushing

FRP Rupture

DEBONDING FALURES OF FRP-PLATED RC BEAMS

受弯加固混凝土梁的各种剥离破坏模态In general, the behavior of FRP-strengthened concrete structures is much

more complex than that of conventional concrete structures

总体而言，FRP加固混凝土结构的破坏机理远比普通混凝土结构复杂

Debonding

Flexural crack

Debonding Critical diagonal crack

(a) IC debonding (b) CDC debonding

Debonding

Debonding

Debonding (c) CDC debonding with concrete cover separation (d) Concrete cover separation

Debonding Debonding

Debonding

(e) Concrete cover separation under pure bending (f) Plate end interfacial debonding

Intermediate crack debonding: (a) 中部剥离

Plate end debonding: (b) to (f) 端部剥离

BOND STRENGTH

BY SINGLE-SHEAR PULL-OFF TEST

lfrp=95mm

DEBONDING FAILURE

BEHAVIOUR OF BONDED JOINTS

Failure generally occurs in the concrete adjacent to the

adhesive-to-concrete bi-material interface

An increase of the bond length L may not increase the

bond strength.

Tensile rupture of the FRP plate generally does not

occur in such a test

Bonded plateConcrete

P

L

INTERMEDIATE CRACK (IC) DEBONDING

IN AN FRP-PLATED RC BEAM

中部裂缝引起的剥离破坏

This is the desired failure mode and can now be

reasonably well predicted

FINITE ELEMENT MODELLING OF INTERMEDIATE

CRACK (IC) DEBONDING

Beam BF8 from Matthys (2000)

COVER SEPARATION FAILURE

This is a very brittle

failure mode and

can become the

controlling failure

mode

PREDICTING PLATE END DEBONDING FAILURES

板端剥离的强度模型

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Vd

b,e

nd/V

db

,s

Mdb,end/Mdb,f

Ceroni et al. (2001)

Fanning and Kelly (2001)

Rahimi and Hutchinson (2001)

Nardo et al. (2003)

Pornpongsaroj and Pimanmas (2003)

Smith and Teng (2003)

For pure shear debonding force

But it is not good enough to be able to

predict the failure: we need to suppress it.

FE Approach for End Cover Separation

Imposed displacement

Vertical restraint

Horizontal restraint

Special cohesive-element-pair,

as shown in Fig. 7-2

Cohesive element and

FRP element

Cohesive element and

stirrup element

Thickness Adjustment

Proposed FE model

Cohesive

element pair

Steel element

Concrete

element

Special cohesive element pair

rs

r t

sr

rs

r t

sr

FE Approach for End Cover Separation

0

15

30

45

60

0 10 20 30 40 50

Sh

ea

r fo

rce (

kN

)

Def lection at mid-span (mm)

NSM test beam (Teng et al. 2006)

NSM beam, FEM (with the radial stress effect)

NSM beam, FEM (without the radial stress effect)

EB test beam (Maalej and Bian 2001)

EB beam, FEM (with the radial stress effect)

EB beam, FEM (without the radial stress effect)

Test

Without the radial stress effect

With the radial stress effect

HOW CAN END COVER SEPARATION BE PREVENTED?

Vertical U-jackets have been explored as end anchorage measures but have been found to be ineffective

SUPRESSION OF COVER SEPARATION FAILURE

Inclined U-jackets have

been found to be much

more effective than vertical

U-jackets

Shear Strengthening of Concrete Beams

RC Beams Shear Strengthened with FRP

The detrimental effect of steel-FRP interaction may become important in large beams

FRP rupture failureDebonding failure

SIZE EFECT IN RC BEAMS SHEAR STRENGTHENED WITH FRP

PI: Dr. G.M. Chen

Guangdong University of

Technology

SIZE EFECT IN RC BEAMS SHEAR STRENGTHENED WITH FRP

PI: Dr. G.M. Chen, Guangdong University of Technology

Axial Strengthening of Concrete Columns

STRENGTHENING OF COLUMNS

BY FRP CONFINEMENT

The Effectiveness of FRP Confinement Depends on Section Forms

The effectiveness of FRP confinement for a rectangular section can be substantially enhanced by curvilinearizing the section

TYPICAL FAILURES OF FRP-CONFINED

CONCRETE CYLINDERS

GFRP-wrapped cylinder CFRP-wrapped cylinder

s

s

sr 2R

sr

t

Efrpteh Efrpteh

Concrete FRP jacket

2R

sc

sr

CONFINEMENT OF CONCRETE BY AN

FRP JACKET

R

tE hfrp

r

es

FLAT COUPON TENSILE TEST OF FRP

(E.G. ASTM D3039 1995)

b

56 138 56

FRP

t Aluminum tab

Strain gauge

COMPRESSION TESTS ON FRP-

WRAPPED CONCRETE CYLINDERS

Strain gauge distribution Compression test

22.5o

67.5o

Finishing end

of fiber sheet

Starting end of

fiber sheet

Overlapping zone

FRP jacket

0o

SG 1

SG 2SG 3

SG 4

SG 5

SG 6 SG 7

SG 8

FRP HOOP STRAIN DISTRIBUTIONS IN

CFRP-WRAPPED CYLINDERS

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 60 120 180 240 300 360Angle from the finishing end of wrapping

(degree)

Ho

op

str

ain

(%

)

C1-1 C1-2 C1-3

C2-1 C2-2 C2-3

C3-1 C3-2 C3-3

Overlapping

zone

113.1o

(150 mm)

A RELIABLE AND UNIFIED

MODEL FOR FRP-CONFINED

CONCRETE SHOULD BE

BASED ON ACTUAL HOOP

RUPTURE STRAINS

STANDARD CONFINED CYLINDER TEST

FOR THE DETERMINATION OF FRP

STRAIN EFFICIENCY FACTOR

FRP strain efficiency factor =

Ratio of the actual FRP hoop

rupture strain to the FRP

rupture strain from flat

coupon tests

Manufacturers should carry

out such tests to determine

the FRP strain efficiency factor

for confinement applications

DIFFERENT TYPES OF STRESS-STRAIN CURVES

ecu

Axial strain ec

'

cof

'

ccf

Axia

l str

ess s

c

ecu

'

cof

'

ccf

Axia

l str

ess s

c

'

cuf

ecc

Axial strain ec ecu

'

cof

'

ccf

Axia

l str

ess s

c '

cuf

ecc

1'' cocu ff

21 '' c oc u ff

2'' cocu ff

weakly-confined

moderately-confined

heavily-confined

LAM AND TENG’S DESIGN-ORIENTED MODEL FOR

FRP-CONFINED CONCRETE

2

'

2

2

4c

co

c

ccc f

EEE ees

tc0 ee

c2

'

c oc Ef es c uct eee

)(

2

2

'

EE

f

c

co

t

ecu

cocc ffE

e

''

2

45.0

,

'1275.1/

co

ruph

co

lcocu

f

f

e

eee''

'

3.31co

l

co

cc

f

f

f

f

R

tEf

ruphfrp

l

,e

LAM AND TENG’S STRESS-STRAIN MODEL

Axial Strain, ec

Axia

l S

tre

ss,

sc

Unconfined Concrete

(GB 50010)

FRP-confined Concete

(Lam and Teng)

fcc

fco

eco

et 0.0033 e

cu

STRENGTHENING OF SHORT COLUMNS:

SECTION ANALYSIS USING A DESIGN-ORIENTED

AXIAL STRESS-STRAIN MODEL

xn

R

si

bc

d

cu

sid

'ccf

si

1

( )nR

u c c si c siR x

i

N b d A

s s s

1

( )nR

u c c si c si siR x

i

M b d A d

s s s

STRENGTHENING OF SQUARE/RECTANGULAR COLUMNS

BY FRP CONFINEMENT

方形/矩形混凝土柱的FRP约束加固

Much more work needs to be done on FRP-confined rectangular columns.

FINITE ELEMENT MODELLING OF FRP-CONFINED

CONCRETE IN A SQUARE SECTION USING A MODIFIED

PLASTIC-DAMAGE MODEL

2 1

2

',

'

60 (1 ) 20

(1 0.06 )

crit

h rupcc

coco

e e

D e

f

f

e

e

Distribution of axial stresses

• Confinement-dependent damage parameter, hardening rule, and flow rule

• Pressure-dependent yield criterion

• Unique properties of non-uniformly confined concrete included

kIJF 1

'

2

Eqn 1:

FE Modeling of FRP-confined square RC

columns

52

Axial stress distributions

A B C

b=150mm, r=24mm, Ej=250GPa, tj=0.33mm, fco=46.0MPa

46.0

46.0

46.0

46.0

46.0

46.0

46.0

46.0

46.0

46.0

46.0

46.0

46.0

A B C

0

10

20

30

40

50

60

70

0 0.005 0.01 0.015 0.02 0.025

Ax

ial

Str

ess

(MP

a)

Axial Strain

A

BC

-0.012

-0.01

-0.008

-0.006

-0.004

-0.002

0

0 0.005 0.01 0.015 0.02 0.025

Co

rner

ho

op

str

ain

Axial Strain

A

B

C

Effective confinement area development

SHAPE MODIFICATION

2a2

b

(a) without rounding (b) with rounding

Curvilinearization of Rectangular Sections

Seismic Retrofit of Concrete Columns

SEISMIC RETROFIT OF RC COLUMNS

• Theoretical models are needed for performance-based seismic retrofit design

STRESS-STRAIN MODEL FOR FRP-CONFINED CONCRETE UNDER CYCLIC AXIAL COMPRESSION

Prediction of the entire stress-strain history

0

10

20

30

40

50

60

70

80

90

0 0.005 0.01 0.015 0.02 0.025

Axial strain ec

Axia

l str

ess s

c (

MP

a)

Cyclic (test)

Envelope (Lam & Teng)

Cyclic (proposed)

f'co = 38.9 MPa

Efrp = 246817 MPa

eh,rup = 0.0123

t =0.33 mm

R = 76 mm

NUMERICAL SIMULATION OF COLUMN BEHAVIOR UNDER CYCLIC LATERAL LOADING

FRP约束混凝土柱的抗震性能模拟

-600

-400

-200

0

200

400

600

-100 -80 -60 -40 -20 0 20 40 60 80 100 120

Lat

eral

Load

(kN

)

Displacement (mm)

Test

Predicted (Push-over with FER)

Predicted (Push-over without FER)

Predicted (Cyclic with FER)

Predicted (Cyclic without FER)

Push

Pull

CS-R1

Strengthening of Concrete Structures with Near-Surface Mounted FRP Reinforcement

NSMR – NEAR SURFACE

MOUNTED REINFORCEMENT

嵌入式FRP加固

Cut a groove

Fill halfway with adhesive

Place FRP into groove

Fill with more adhesive

Level the surface

concrete

groove

FRP bar

adhesive

FRP strip

adhesive

LONG-TERM MONITORING USING FIBER-

OPTIC SENSORS

grating region

Cladding

Protective coating

9um

125um

250um

Core

LONG-TERM MONITORING USING FIBER-

OPTIC SENSORS

Input light Reflected light Transmitted light

Basic principle of FBG sensors

PULTRUSION OF SMART FRP BARS

Optic fiberGlass fiber

EMBEDMENT OF OPTIC FIBERS

SMART FRP BARS

SMART FRP BARS

OUTLINE

• Background and history

• Strengthening of concrete structures

• Strengthening of steel structures

• FRP composites in new structures

• Concluding remarks

BOND CRITICAL APPLICATIONS-FAILURE MODESDebonding failure within the steel substrate is impossible!

Steel

Adhesive

CFRP

Interlaminar failure of FRPFRP Rupture

FRP-adhesive interfacial debonding-

adhesion failure

Failure within the adhesive-

cohesion failure

Steel-adhesive interfacial debonding-

adhesion failure

Adhesive

properties +

Surface

characteristics

Adhesive

properties

Adhesive

properties +

Surface

characteristics

BOND BEHAVIOUR BETWEEN STEEL

AND CFRP

In-plane bending failure (material failure)

Lateral buckling

Debonding at plate ends

Yielding-induced debonding

Local buckling of compression flange

Local buckling of web

Flexural Strengthening of Steel BeamsFailure Modes

Top flange local buckling

Unstrengthened section

Web failurefailure

buckling or yielding

CONVENTIONAL SECTION ANALYSIS

can be used to evaluate the section moment capacity if debonding does not occur

Neutral axis

f y

Elastic region

f y

FRP/adhesive interface debonding FRP rupture FRP delamination

Adhesive layer failure

Adhesive/steel interface debonding

COHESION FAILURE WITHIN THE ADHESIVE LAYER IS

THE DESIRED DEBONDING FAILURE MODE

Cohesion failure

Adhesion failure

Adhesion failure

FATIGUE STRENGTHENING

• Externally bonded FRP

reinforcement is a highly

effective method for

enhancing fatigue

resistance

• Pre-stressed CFRP

laminates are

particularly effective

• The desirable level of

pre-stressing depends

on

– Static strength of the

bonded interface

– Fatigue strength of the

bonded interface

Pre-stressed CFRP platea. Crack closure

b. Stress intensity factor reduction at the crack tip

Cracked steel plate

Pre-stressing the CFRP plate can close the crack

LOCAL BUCKLING IN A STEEL TUBE

FAILURE MODE OF FRP-CONFINED

CONCRETE-FILLED STEEL TUBES, D/t =101

AXIAL LOAD-SHORTENING CURVES, D/t = 101

BCFT

3-ply

0

500

1000

1500

2000

2500

3000

0 5 10 15

Axial deflection (mm)

Ax

ial

load

(k

N)

BCFT

1-ply2-ply

3-plyFRP rupture

CONSTANT AXIAL AND CYCLIC LATERAL LOADING TESTS

Failure modes

Unconfined CFST

Weakly confined CFST

Strongly confined CFST

OUTLINE

• Background and history

• Strengthening of concrete structures

• Strengthening of steel structures

• FRP composites in new structures

• Concluding remarks

FRP bars

Bridge deck Concrete-filled FRP tube

FRP PRODUCTS FOR APPLICATIONS IN

NEW CONSTRUCTION

Wide Use of FRP Composites in Other IndustriesFRP复合材料在其它工业中应用广泛

CFRP in the B787 Plane波音B787飞机

The first B787 plane was delivered to All Nippon Airways on 25

September 2011; first commercial flight on 26 October 2011.

Each plane uses 32 tonnes of CFRP，including 23 tonnes of carbon fibers;

CFRP constitutes 61% of the weight and 80% of the volume of the materials

used. The plane consumes 20% less fuel due to the use of CFRP.

Dreamliner梦想飞机

http://www.aviationnews.eu/2011/02/24/boeing-completes-1000th-787-flight/

CFRP High-Speed Inter-City BusesDelft University of Technology

CFRP高速公共汽车

FRP Reinforcing Bars

Top Mat for Bridge Decks: FRP Bars from Hughes Brothers

Replace steel bars in corrosive environments

Courtesy of Prof A Mufti, University of Manitoba

MANITOBA FLOODWAY PROJECTSTEEL-FREE CONSTRUCTION

Modified from a slide provided by Prof. Aftab Mufti

CFRP Cables Used in Storchen Bridge in

Switzerland

(Image from LC Bank: Composites for Construction, Wiley and Sons)

Storchen Bridge in Switzerland

This bridge in Winterthur,

Switzerland was built in 1996. The

two spans, one 63 m and the other

61 m, are supported by a central A

frame tower with 24 cables

including 2 CFRP cables

(Image from http://www.flickr.com/photos/71015858@N00/403151078/)

FRP Facade Panels and FormworkUsed in Hong Kong

ç

FRP Covers for Sewage Treatment Works in Hong Kong

•

•

•

FRP in Combination with Sea Sand Concrete for Constructing New Structures？

River sand conservation

Role in marine development

Research on durability of FRP in sea sand concrete needed

http://www.bondibeach.com/

Bondi Beach, Sydney, Australia

FRP-enabled Hybrid Structures

GFRP Filament Wound Tubes

Fabrication of FRP Confining Tubes with Fibers

Oriented Close to the Hoop Direction

Hybrid FRP-Concrete-Steel Tubular Columns

Allowed by the Chinese National Standard

Concrete-filled FRP tube (CFFT)

FRP tube

Concrete

Steel tube

Steel bars

FRP tube

Concrete

Hybrid FRP-concrete-steel double-skin tubular members (DSTCs or

DSTBs)

Axial compression failure of concrete-filled FRP tubes with fibers oriented close to the hoop direction

Steel bars

FRP tube

Concrete

From Karimi et al. (2011)

Columns Based on FRP Confining Tubes

Double-tube concrete columns (DTCCs)

FRP tube

Concrete

Steel tube

Double-Tube Concrete Columns

with a High Strength Steel Tube

Double-Tube Concrete Columns

with a High Strength Steel TubeFRP tube

Concrete

Steel tube

Hybrid FRP-Concrete-Steel Double-Skin

Tubular Members

Various Section Forms

FRP tube

Steel tube

Concrete

FRP tube

Concrete

Steel tube

(a) (b)

(c) (d)

(a) (b)

(c)

Failure Modes of Hybrid DSTCs under Axial

Compression

0 5 10 15 20 250

1000

2000

3000

4000

5000

6000

7000

Axial Shortening (mm)

Axi

al L

oad

(kN

)

D40-6FW

D80-6FW

D80-6FW

D110-6FW

D80-10FW

D110-10FW

Load-Shortening Responses of Hybrid

DSTCs under Axial Compression

Vertical actuator

Top plate

Bottom plate

Hinge

Column head fixture

Hinge

Horizontal actuator

Steel bolts

Hybrid DSTCs under Axial Compression & Cyclic

Lateral Loading

DSTC No.2: tested on 29th Dec 2010

Concrete: fc=117.0MPaD = 300mmLength: 4.5D = 1350mm

Steel tube: fy=364MPaD = 219mm; t = 6mmD/t = 36.5

FRP tube: Inner D = 300mm;t = 6mm

Void ratio=219/300=0.73

F=Ac*fc+As*fy=5302.0kNAxial load：n=0.2N=F*0.2=1060.4kN

DSTC No.2

Before Test

Department of Civil and Environmental Engineering

Cyclic Lateral Loading Tests of Hybrid DSTCs

The rounded hysteretic curve indicates

excellent ductility/seismic resistance even

with the use of high strength concrete

Loading Process of Specimen D116-6-0.2 Concrete strength: 117 MPa

Axial load ratio: 0.2

Thickness of FRP tube: 6 mm

Accelerated video clip

Department of Civil and Environmental Engineering

Cyclic Lateral Loading Tests of Hybrid DSTCs:

Detailed view of the failure process

Local view of the damage process

Tensile cracking of resin in FRP

Compression damage of resin in FRP

Crushing of concrete

Rupture of FRP tube in hoop direction

Flexural Tests on Double-Skin Tubular

Beams (DSTBs)

Failure Modes of DSTBs

Concluding Remarks

FRP strengthening has become accepted as a mainstream technology, although much more research is still needed on issues such as:

Strengthening with pre-stressed FRP reinforcement

Performance in severe environments

Performance under extreme loading

FRP-enabled hybrid structures offer many opportunities for innovations in structural forms

FRP composites have an excellent future in bridge and marine construction

Long-term performance and life-cycle design are crucial for future successes, particularly in new construction

Acknowledgements

Funding support from the following organizations is gratefully acknowledged:

Research Grants Council of Hong Kong SAR

National Natural Science Foundation of China

Ministry of Science and Technology of China

Innovation and Technology Fund of Hong Kong SAR

The Hong Kong Polygenic University

Thanks are also due to the collaborators and members of my research group