the use of frp as embedded reinforcement …ci.group.shef.ac.uk/ci_content/frp/pw_2004.pdfthe use of...

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

THE USE OF FRP ASEMBEDDED REINFORCEMENT

IN CONCRETE

Peter Waldron

Centre for Cement and ConcreteUniversity of Sheffield, Sheffield, S1 3JD, UK


Advanced Composites (Applications)

- High Strength- Light Weight- Exceptional Durability


Composites in Civil Engineering: Why?

Non Magnetic

App

licat

ions

Durability

High Strength

Durability

Strengthening and

Rehabilitation

ACI 440ISIS Canada

fib TG 9.3IStructENGCC

JSCE



Chloride PenetrationChloride Penetration

0.0000

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.7000

12 25 37.5 50 75

Depth (mm)

Chl

orid

e %

of C

oncr

ete

5 Years10 Years20 Years30 Years40 Years50 Years


Applications: Durability

Slope reinforcement

Reinforcement for tunnels


Applications: Durability

Fender - Qatar

Creek Bridge - Sierrita de la Cruz (USA)


Applications: Electromagnetic Neutrality

Maglev train - Japan

Precast post and panel fencingHemel Hempstead (UK)


Applications: High Strength

Birdie Bridge - Ibaragi Prefecture, Japan


FRP RC Bridges – Worldwide Growth

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004Estimated Market Size: 85 M TonnesEstimated Market Size: 3.5 M Tonnes

Consumption of Steel Reinforcing Bars

Worldwide Consumption ofSteel Reinforcing Bars


Reinforced Composites in the Construction Market


Composites in Civil Engineering: Why not?

•Higher raw material cost

•Lower stiffness

•Lack of ductility

CONFIDENCE


FRP RC and Code Development

19871991

1993

1995

1997

1999

2001

1992

1994

1996

1998

2000

20022003

2004

JSCE Committe on CFRM, CSCE technical Committee

CSCE Report, ACI 440, BRITE-EURAM Project

JSCE State-of-the-Art Report

EUROCRETE Project

Design Recommendations- JSCE- EUROCRETE

ConFibreCrete Network

CSCE Design Recommendations

IstructE Design RecommendationSwedish National code

fib Bulletin 14, ISIS Manuals, ACI 440.1R

ACI 440.2R, CUR Recommendations

ACI 440.1R (revised)

fib TG 9.3

Concrete Society - TR55, fib bulletin 10

CurvedNFR

Concrete Society - TR55 (revised)


RECOMMENDATION FORDESIGN AND CONSTRUCTIONOF CONCRETE STRUCTURESUSING CONTINUOUS FIBER

REINFORCINGMATERIALS

CONCRETE ENGINEERING SERIES

FRP RC and Code Development


Flexure and Cracking

Punching Shear

Shear

Bond

Design Philosophy Plate Bonding

Column Confinement

RC

EBR

Shear Strengthening

Research on FRP at Sheffield

Curved-NFR


•Different behaviour

•Existing design codes are based on the use of steel reinforcement

•Existing design equations need to be re-examined

•New design philosophy

Steel RC vs FRP RC


FRP RC Steel RC

Structural Considerations: Flexure



Ductility? Deformability?



b

FRP

Strain

ε cu

x = ξ d

2%

d

b

d

0.5%

Stress

σε

fcu

Steel

)4.01(68.0 2 ξξ −≈ cdSd fbdM

cuf

cdreqf E

fεξ

ξρ⋅−

≈168.0 2

,

Bending moment capacity of therectangular FRP RC section:

Required FRP reinforcement ratio:



Modes of failure: Concrete CrushingRupture of FRP Reinforcement


0

20

40

60

80

100

120

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Loa

d (k

N)

Crack width (mm)

Calculated widthCalculated strain

Calculated widthMeasured strain

Measured width

Structural Considerations: Cracking

For good bond, existing strain based equations can be used

BS8110 equations are non-conservative


V = Vc + VsV = Vc + VsConcrete

contributionEmpirical equation models

- concrete in compression- aggregate interlock- dowel action

Contribution of shear r/ment+

Truss analogy theory

Shear Design

Limiting Strain = 0.2% - 0.25%

V = Vc + VsV = Vc + Vs

•Similar shear mechanisms?

•Sum of contributions?

•Limiting strain concept?


Shear Design

Shear of FRP RC Beams

Punching Shear of FRP RC slabs


Limiting Strain = 0.45%

V = Vc + VsV = Vc + VsShear Design


•Pull-out Cube tests:4 phases, more than 130 specimens

•Beam tests:4 phases, more than 37 beams9 of them designed to fail in bond

•International Round Robin TestsPull-out + Splitting

767 767766

250

Single bar anchorage:

L

Bond of FRP Bars in Concrete


Concrete

Failure interface in resin

Bar fibers

Bar resin Failure interface in concrete

Concrete

FRP Bar

Embedment length

Pull-out direction

Wedging effect




•GFRP bars splitting bond strength around 65 -70% of CFRP bars

•Possible Reason ?

•Difference in Young’s Modulus ⇒ Difference in angle a

CFRP bar

Microcracksα

Fb

Fsp

GFRP bar

αFb

Fsp

ds


Shaping The Future of FRPs: Curved Non-Ferrous R/ment

Longitudinal direction

Transverse direction

•State of stress

•Reinforcement geometry

•Constituent materials

•Manufacturing processes


15

32

15050450

60

250

60 60130

38

5085

50



•Reinforced concrete memorial bases



0%

1%

2%

3%

4%

0 100 200 300Resistance-Capacity, kN

Applied LoadBondShearFlexure

Rel

ativ

e Fr

eque

ncy

Design Philosophy

Resistance R

Load E

ffect

S

PS,

R (

S,R

)

S = R∴Limit State

S < R∴ Safe

S > R∴ Failure

Resistance R

Load E

ffect

S

PS,

R (

S,R

)

S = R∴Limit State

S = R∴Limit State

S < R∴ Safe

S > R∴ Failure

S > R∴ Failure


Structural reliability assessment:Monte Carlo Simulation method

with Latin Hypercube andConditional Expectation

variance reductiontechniques

Resistance R

Load E

ffect

S

PS,

R (

S,R

)

S = R∴ Limit State

S < R∴ Safe

S > R∴ Failure

Resistance R

Load E

ffect

S

PS,

R (

S,R

)



S < R∴ Safe

S > R∴ Failure

S > R∴ Failure

Design Philosophy: Assessment Methodology


• Conventional fundamental RC principles can be used for design

• Basic design guidelines exist• Different philosophy should be adopted to address the issue of safety

• Advanced guidelines soon to come• There are challenges with all new material technologies

• New structural concepts can be developed• Exciting time for Civil Engineering

Conclusions

the use of frp as embedded reinforcement …ci.group.shef.ac.uk/ci_content/frp/pw_2004.pdfthe use of...

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