International Workshop on Infrastructure Applications of FRP Composites, Wollongong, 6 December 2015

Response of Concrete Structures

p , g g,

Response of Concrete Structures Reinforced with GFRP Bars to Impact

LoadingA/Prof Alex Remennikov, Matthew Goldston, Dr Neaz

SheikhCentre for Infrastructure Protection & Mining Safety

(CIP&MS)F l f E i i d I f i S iFaculty of Engineering and Information Sciences,

University of Wollongong

Objectives of this studyObjectives of this study Experimentally investigate the flexural behaviour and impact

f GFRP RC b d t ti d i t l diresponse of GFRP RC beams under static and impact loading

Study the effects of multiple parameters on static and Study the effects of multiple parameters on static and dynamic performance of GFRP RC beams: Concrete strength and effectiveness of HSCg Effect of reinforcement ratio Effect of impact energy and energy absorption

Compare failure modes under static and impact loading for GFRP RC beamsGFRP RC beams

Develop damage prediction model for impact loading.p g p p g2

FRP Reinforcement and Climate Change

Change in probability of chloride penetrationCarbonation induced corrosion of concrete structures by 2100: change in probability of

Wang X Stewart M G and Nguyen M (2012) Impact of Climate Change and Corrosion

Change in probability of chloride penetration induced corrosion of concrete structures by 2100

structures by 2100: change in probability of corrosion initiation

Wang, X., Stewart, M.G. and Nguyen, M. (2012), Impact of Climate Change and Corrosion and Damage to Concrete Infrastructure in Australia, Journal of Climatic Change, 110(3-4): 941-957.3

Why use GFRP in concrete ?structures?

• Millions spent on bridge maintenance each year due to reinforced concretereinforced concrete corrosion and spalling.

• Reinforced concreteReinforced concrete structures estimated AUD $26 billion repair cost in Australia.

• Increased service life and reducedand reduced maintenance costs.

• For example, Seacliff bridge is painted with a protective coating to prevent corrosionprevent corrosion.

Why use GFRP in concrete ystructures?

S l d d• Severely corroded reinforcing steel in these bridge columns hasbridge columns has resulted in spalling of the concrete cover and exposure of the steel reinforcement.

Importance of Impact Resistance FRP RC Structures

• Coastal infrastructure subjected to impact loads.

• Marine structures including bridge decks andincluding bridge decks and piers subjected to collision loadsloads.

• No previous research on i i f FRPimpact resistance of FRP RC structures.

6

Flexural Failure Modes• There are three potential flexural failure modes for FRP-

reinforced concrete sections: Balanced failure – simultaneous FRP bars tensile rupture and

concrete crushing Compression failure – concrete crushing prior to FRP tensile rupture Tension Failure – tensile rupture of the FRP prior to concrete

crushing• Compression failure is the most desirable of the above failure

d Thi f il d i l i l t th t i f ilmodes. This failure mode is less violent than tension failure,and is similar to the failure of an over-reinforced section whenusing steel reinforcement.

T i f il i l d i bl i t il t f FRP• Tension failure is less desirable, since tensile rupture of FRPreinforcement will occur with less warning. Tension failurewill occur when the reinforcement ratio is below the balancedreinforcement ratio for the section This failure mode isreinforcement ratio for the section. This failure mode ispermissible with certain safeguards.

Balanced Failure of FRP-Reinforced Beam

Experimental Program – Phase 1Specimen Name

Predicted Mode

Experimental Program Phase 1Specimen Name

of Failure

40-#2S-0.5-S&I 0.5 0.36 1.39 40 Balanced

40-#3HM-1.0-S&I 1.13 0.23 4.9 40 Concrete Crushing

40-#4HM-2.0-S&I 2.03 0.26 7.8 40 Concrete Crushing

80-#2S-0.5-S&I 0.5 0.61 0.82 80 GFRP Rupture

80-#3HM-1.0-S&I 1.13 0.40 2.83 80 Concrete Crushing

80-#4HM-2.0-S&I 2.03 0.44 4.61 80 Concrete Crushing

Beam Sections

Test 1 - Two Bars Test 2 - Three Bars Test 3 - Four BarsTest 1 Two Bars Test 2 Three Bars Test 3 Four Bars

Experimental Setup – Phase 1• Static Testing – Four Point Bending

Experimental Setup Phase 1

Experimental Setup – Phase 1• Impact Testing – Small Drop Hammer

Experimental Setup Phase 1

‣ 110 kg Drop Hammer

‣ Attached to a low friction linear‣ Attached to a low friction linearbearing (minimal losses due tofriction expected)

‣ High Speed Camera – Measure Mid– Span Deflection

‣ Load Cells attached to drophammer and at the supports tomeasure resistance

‣ Height kept constant, 1200 mm

E i l

Static Testing

BeamExperimental

Failure mode

40 #2S 0 5 S 3 0 13 8 4 60 52 2 B l d40-#2S-0.5-S 3.0 13.8 4.60 52.2 Balanced

40-#3HM-1.0-S 5.0 39.2 13.1 60.4 Concrete Crushing

40-#4HM-2.0-

S5.8 49.7 16.6 59.9 Concrete Crushing

80-#2S-0.5-S 3.6 15.5 5.17 54.5 GFRP Rupture

80-#3HM-1.0-S 5.9 42.6 14.2 56.3 Concrete Crushing

80-#4HM-2.0-5 7 49 5 16 5 47 3 Concrete Crushing

S5.7 49.5 16.5 47.3 Concrete Crushing

Results

Video ofResponse of GFRP reinforcedResponse of GFRP reinforced

beambeam

50

60

30

40

(kN

)

Beam 40-#2S-0.5SBeam 40-#3HM-1.0SBeam 40-#4HM-2.0S

20

30

Loa

d

Beam 80-#2S-0.5SBeam 80-#3HM-1.0SBeam 80-#4HM-2.0S

0

10

0 20 40 60 800 20 40 60 80Deflection (mm)

• Static Testing• Static Testing Concrete Crushing

GFRP RuptureGFRP Rupture

‣ Balanced Failure of Specimen 40-#2S-0.5-S

‣ Concrete crushing on top surface and rupture of

‣ Concrete Crushing of Specimen 40-#3HM-1.0-S

‣ Concrete crushing on top surface, vertical flexural cracks g p ptensile GFRP rebars simultaneously

g p ,

Experimental Resultsp Quasi-Static

80-#3HM-1.0-S

80-#4HM-2.0-SLoading Energy before maximum load,

defined as the energy the beam

80-#2S-0.5-S

defined as the energy the beam could sustain before a significant drop in load

O i f d i

Energy before Max Load

40-#4HM-2.0-S

Over–reinforced specimens displayed signs of additional energy after maximum load was attained. Due to concrete confinement the concrete had

Energy after Max Load

40-#2S-0.5-S

40-#3HM-1.0-Sconfinement, the concrete had the ability to undergo further strains.

0 1000 2000 3000 4000Energy Absorption (J)

Under–reinforced and balanced specimens failed immediately once rupture of GFRP bars occurred, no energy sustain

f i l dafter maximum load

Experimental Program – Phase 2p gBeam Name Design Failure

Mode

80-#2S-0.5-S 0.5 80 GFRP Rupturep

80-#3HM-1.0-S 1.0 80 Concrete Crushing

80-#4HM-2.0-S 2.0 80 Concrete Crushing

120-#2S-0.5-S 0.5 120 GFRP Rupture

120-#3HM-1.0-S 1.0 120 Concrete Crushing

120-#4HM-2.0-S 2.0 120 Concrete Crushing

120-#3HM-1.0-I-355 1.0 120 Concrete Crushing

120-#3HM-1.0-I-533 1.0 120 Concrete Crushing

120-#3HM-1.0-I-710 1.0 120 Concrete Crushing

120-#4HM-2.0-I-550 2.0 120 Concrete Crushing

120 #4HM 2 0 I 825 2 0 120 C C hi120-#4HM-2.0-I-825 2.0 120 Concrete Crushing

120-#4HM-2.0-I-1100 2.0 120 Concrete Crushing#2S#3HM#4HM

4 mm Ø Steel Stirrups @ 50 mm c - c

2400#4HM

150

50 GFRP and ConcreteStrain Gauges19

HS Concrete Mix DesignsHS Concrete Mix DesignsMaterial 80 MPa 120 MPa

Bastion General Purpose Cement 540 kg/m3 600 kg/m3

Fine Grade Fly Ash 40 kg/m3 N/Ay g

Micro Silica Densified Silica Fume 40 kg/m3 40 kg/m3

10 A t 1040 k / 3 1020 k / 310 mm Aggregate 1040 kg/m3 1020 kg/m3

Coarse Sand 420 kg/m3 450 kg/m3

Fine Sand 100 kg/m3 150 kg/m3

Sika Viscocrete PC HRF2

(Superplasticiser)4 L/m3 5 L/m3

Water 160 L/m3 155 L/m3

• Provided by a technical concrete officer from Boral• At time of testing, concrete compressive strength = 90 MPa (Static

Testing) and 116 MPa (Impact Testing)20

Quasi-Static Response of GFRP HS CRC Beams

Performed prior to impact loading Performed prior to impact loading to evaluate energy absorption capacity

Three Point Bending Bi-Linear load-deflection

Relationship Two failure modes:

GFRP Rupture Concrete Crushing

R it (“d tilit ”) Reserve capacity (“ductility”) for over-reinforced GFRP RC beams

21

Failure Modes under Quasi-Static LoadingLoading

1. GFRP Rupture (Beam 120-#2S-0.5-S)il f G

14

16Failure of GFRP Bars

8

10

12

(kN

)

4

6

8

Loa

d 0

2

0 20 40 60 80 1000 20 40 60 80 100Deflection (mm)

• Sudden and unexpected failure (no prior warning)warning)

22

Failure Modes under Quasi-Static L diLoading

2. Concrete Crushing (Beam 120-#4HM-2.0-S)

60

70

80

Concrete Cover Crushing

GFRP Rupture

40

50

60

oad

(kN

)

g

Reserve Capacity

Concrete cover crushing

Followed by10

20

30Lo Reserve Capacity

(“Ductility”)

Followed by 0

0 20 40 60 80 100 120 140 160Deflection (mm)

• Common load-deflection trend for the over-reinforced GFRP RC beams

GFRP Rupture• Preferred over under-reinforced

sections 23

Impact Response of GFRP RC BeamsImpact Response of GFRP RC Beams 580 kg Drop Hammer Apparatus

GFRP RC beams subjected to 0% % 100%50%, 75% and 100% energy

absorption capacity of under quasi-static loadingquasi static loading

High speed camera to measure g pmid-span deflection using image processing techniques

Failure Mode:o Dynamic Punching Failureo Dynamic Punching Failure

24

Video of ImpactResponse of GFRP reinforcedResponse of GFRP reinforced

beambeam

Dynamic Time-History of Impact Loading

250

200 Beam 120II-#3HM-1.0-I-0.355

150

kN) Inertial Resistance

100Loa

d (k

Dynamic Bending Resistance

50

Dynamic Bending Resistance

00 0.05 0.1 0.15 0.2

Time (s)26

Dynamic Mid-Span DeflectionsDynamic Mid Span Deflections300

250

200

lect

ion

(mm

)

100

150

Mid

-Spa

n D

efl

50M

•• Prior to ImpactPrior to Impact

00 0.05 0.1 0.15

Time (s)

•• At Maximum DeflectionAt Maximum Deflection

GFRP RC Beam 120GFRP RC Beam 120--#4HM#4HM--2.02.0--II--82582527

Failure Modes for Static and Impact LoadsFailure Modes for Static and Impact Loads

GFRP splitting of fibersGFRP splitting of fibers

GFRP RC Beam 120-#3HM-1.0-S

GFRP RC Beam 120-#3HM-1.0-I-710

Static Loading• Flexural Cracks

Impact Loading• Dynamic punching failure (localised concrete

crushing on the top surface with the majority of • Flexural Cracks• Concrete crushing of cover• GFRP splitting of fibers

damage occurring in the impact area). • Fewer cracks observed. • Minor shear cracking around impact area• Minor splitting of GFRP fibres at midspan

28

C l iConclusions

Further Research• Experimentally investigate different composite materials

(carbon, aramid) and varying cross-sections (I-Beam, T–( , ) y g ( ,Beam) under impact loading.

• To more accurately verify dynamic equilibrium, placeaccelerometers across the surface of the beam.

• Investigate the size effect, to model real life size structures.• Develop a non-linear finite element model to simulate the

flexural and shear behaviour of GFRP RC beams under staticd i t l diand impact loading.