FRCindustrialapplications inItalyM. di PriscoDepartment of Structural EngineeringPolitecnico di Milano

Why fibres in the precast industry?

fibres are a spread reinforcement and do not substitute main reinforcement!

• thickness reduction (no cover limitations)

• larger design freedom in the drawing of cross-section profile

• prevention of complex reinforcement detailing

• major industrialisation degree in the production process (no mesh handling and placing)

• better spreading, continuously adjustable

• no check ot tolerances on reinforcement position

• set-up of the mix-design to conserve a good workability

• checking of fibre dispersion

• lack of well-established design procedures

25 January 2013

3

Model Code: material and structure design

Concrete’s

Chapter §5.6 Chapter §7.7

FRC to substitute transverse reinforcement

the material: mix design of the matrix

+50 kg/m3 low-carbon steel fibers 45/30

or

50 kg/m3 high-carbon steel fibers 80/30 fcm= 75 MPa

UNI 11188: defect introduction

Compressed zone

Tensile zone

0

10

20

30

40

50

60

Fibr

e co

nten

t [kg

/m3 ]

Bottom Plate 47,10 37,93 42,77 36,58 48,90 37,33 40,18 44,49Web (bottom) 42,41 29,61 51,68 51,41 42,02 53,50 43,15 40,26Web (top) 50,39 49,52 46,58 48,18 48,29 45,53 50,81 53,06

Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Section 7 Section 8

by Ferrara and Meda, 2006

Bending tests on roof elementsUPN 300

HEB 160HEB 260

HEB 550

lcs,wing

lcs,slab

by di Prisco, Failla,Plizzari, 2003

COMPARISON - SECTION CLoad - Total displacement

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300

Total displacement [mm]

Load

[kN

]

NG-PL 80/30NG-PL 45/30NG-PL RCElastic limit

First cracks

80/3045/30

R/C

by di Prisco, Failla,Plizzari, 2003

the bridge ... of the characteristic structural length

This image cannot currently be displayed.

lcs1lcs1

w

lcs2lcs1

w

lcs

Gf

Test data

tj [day]

fcm [MPa] fibre Cf

[kg/m3] MR,CEB [kNm]

MR,EC2 [kNm]

MR,sper [kNm]

Weight [kg] failure

25/07/02 69 72.05 45/30 50 614.8 (+1.9%)

567.7 (-5.9%) 603.4 6580 lb / wing

30/07/02 56 67.00 80/30 50 634.5 (+1.5%)

567.7 (-9.2%) 625.1 6500 lb / wing

06/09/02 35 74.07 - - 582.3 (+5.9%)

567.7 (+3.3%) 549.6 5780 lb / wing

0 10 20 30Curvature [1/km]

0

100

200

300

400

500

600

700

M[kNm]

expUNI,nRILEM (kh=1.00)RILEM (kh=0.56)no fibres

Mexp,max

longitudinal cracks

0 1 2 3[10-3]

0

2

4

6[N/mm2] RILEM

UNInwing

UNInslab

Carico eccentrico

0

1500

500

1000

-500

VlasovEF sezione AEF sezione BEF sezione C

Mtrasv[Nm/m]

ascissa/larghezza0 11/2

0

4500

1500

3000

-1500

-3000

VlasovEF sezione AEF sezione BEF sezione C

Mtrasv[Nm/m]

ascissa/larghezza0 11/2

Al collasso

Verifica elastica con E.F.elastic check by FEeccentric load

at failure

Longitudinal roofing elements

Table 1. Material description Steel Polypropylene

Code

Rcm [MPa]

cf [kg/m3]

lf/df lf [mm]

ffu [MPa]

cf [kg/m3]

lf [mm]

ffu [MPa]

P 61.19 - - - - - - -

S-1 54.43 25+ 25

75 50

60 30

1192 1192 3 12 450

S-2 57.09 50 80 30 2300 3 12 450 S-3 61.09 50 45 30 1250 3 12 450

by Bonalumi et al., 2006

Materials investigated

0 1 2 3 4CODm (mm)

0

2

4

6

N[MPa]

CPCRDPDR

S-2

0 1 2 3 4CTODm (mm)

0

2

4

6

8

10

N[MPa]

Specimen 1Specimen 2Specimen 3

S-2

Italian Standard test Structural test

specimen 1,2,3averagee-s lawr-p law

0 1 2 3 4CODm (mm)

0

2

4

6

N[MPa] S-2

0 1 2 3 4CTODm (mm)

0

2

4

6

8

10

N[MPa]

specimen 1,2,3averagee-s lawr-p law

S-2

e-s

r-p

Unnotched0

0.5

1

1.5

2

2.5

3

Mexp/Mrd

Notched0

0.25

0.5

0.75

1

1.25

1.5Mexp/Mrd

elasto-softening law

rigid-plastic law

concentrated load distributed load

0 10 20 30 40(mm)

0

1

2

3

4

P (kN)

W-PW-S-1W-S-2W-S-3

Safety

S1 S2 S3S1 S2 S3

W-PW-S-1W-S-2W-S-3

0 10 20 30 40(mm)

0

1

2

3

4

P (kN)

point load distributed load

fc,28= 67 MPaHPSFRC 75/50/45-30

140°

30 mm.

2.0

mm 2.0 mm.

l / df = 480,

62

fiber content 50kg/m3

cement + fly ash = 315 + 105 [kg/m3] siliceous aggregate acrylic superplasticizer 1.7% of bindermaximum aggregate size 15 mm water/binder ratio = 0.38

Material mix design

strength class

type of fiber aspect ratio – fiber length

Fire resistance

T [°C]

t [h]

+30°C/h

-12°C/h

t=2h

Tmax

Tmax = 200, 400, 600 °C

Heating process before testing

Post thermal cycle characterization

• uniaxial compression of cubic specimens

•uniaxial tension of prismatic specimens

1 2 3

6 5 4

84

60

60

150

mm

50

LVDT

Uniaxial tension: fixed-end plate

Post thermal cycle characterization

0.0 0.1 0.2Crack width w (mm)

0.0

2.0

4.0

t(N/mm2)

200°C

400°C600°C 20°C

t

w

Post thermal cycle characterization

Load

Deflection75

60

500

150 150 150

25 450 25

4-Point Bending tests• 4 materials

75/50/45-3075/50/80-3040/50/45-3040/35/45-30

•2 characterization procedures- (post thermal cycle - BC) cold specimen - at assigned temperaturehot specimens (BH)

•3 nominal identical tests

•5 reference maximum temperature (T=20, 200,400, 600, 800 °C)

Which is the difference between a hot and a post-thermal cycle characterization?

108 specimens tested

0 1 2 3 40

2

4

6T75/50/80-30

(d)

Deflection [mm]

Load[kN]

Which is the difference between a hot and a post-thermal cycle characterization?

0 1 2 3 40

2

4

6T75/50/45-30

(c)

Deflection [mm]

Load[kN]

BHCBCC

T=20°C

200

400

600800

Thermal decay laws

Description of the retaining structure

New design aspects

Main Concepts• to strenghten the structure “ground slope”• to use precast elements to accelerate the in-situ operations• to apply FRC materials to benefit of local thoughness• to use such construction as an environmental structurecarefully monitored to check the reliability of both the structure and the monitoring exp. techniques• to calibrate NDT, by perfectly knowing the mechanicalcharacteristics of the materials

Structural design

S23030

Similarities:- cross-section- concrete mix- fibre type and content

(50 kg/m3 = 0.6%)- number (4), diameter (0.6’’)

and initial stress in the strands (1350 MPa)

Experimental programme

Not Post-tensioned beams

30

30

Total: 15 beams (6 typologies) 30

30

R0

2 x

S0

3 x

Experimental programme

Post-tensioned beams

30

30

30

30

S1

3 x 3 x

30

30

P1

2 x 2 x

P2 30

30

S2

Construction phases: safety operations

Construction phases: drainage setting-up

Construction phases: testing on plates

Ltf

LtbLfree

Lconstraint

Le

Construction phases: relief, template positioning and anchor fixing

Construction phases: template formwork

Construction phases: ground anchor boring and grouting

Construction phases: casting of bedding bottom layer

Construction phases: panel handling

Construction phases: anchor plate positioning

Construction phases: final view

constituent quantity [kg/ m3]Cement (CEM I

52.5R) 400

Coarse aggregate A 569 (da < 12)Coarse aggregate B 403 (da < 8)

Sieved sand 676 (da < 4)Calcareous filler 96 (da < 0.1)

Steel fibres 60/0.8 50Superplasticizer/

cement ratio 2.2 %

Water/binder ratio 0.39

Material characterization: mix design

Material characterization: workability suitable tests

Test 1 Test 2 Test 3 Cast Slump T50

Ratio Scatter Ratio Scatter Ratio Scatter [mm] [sec]Sector [kg/m3] [%] [kg/m3] [%] [kg/m3] [%] 1 625 8.81 40.01 -20.24 60.33 -7.73 44.43 -25.3 2 618 10.62 54.48 8.61 63.36 -3.10 69.33 16.56 3 560 12.03 54.16 7.98 68.12 4.19 53.62 -9.85 4 666 5.44 47.25 -5.79 61.15 -6.48 64.66 8.71 5 580 12.65 45.34 -9.62 64.12 -1.93 57.69 -3.01 6 714 6.26 50.35 0.37 76.00 16.23 61.94 4.13 7 685 6.87 46.58 -7.13 70.63 8.02 62.41 4.93 8 686 6.28 57.56 14-76 66.95 2.39 62.87 5.69 9 658 8.19 55.71 11.06 57.82 -11.57 58.37 -1.87 10 641 10.5Mean 50.16 65.39 59.48 Mean 643 8.7

0 0.2 0.4 0.6 0.8

CTODm [mm]

0

1

2

3

4

5

6

7σΝ

[MPa] P1AR0AR0BAverage

0 0.5 1 1.5 2 2.5 3 3.5 4CTODm [mm]

0

1

2

3

4

5

6

7 [MPa]

S0AS0BS0C

S1AS1BS1C

S2AS2BS2Caverage

P/2 P/2

P/2 P/2

clip gauge(CMOD)

LVDTs(CTOD)

PLAIN SFRC

Material characterization: bending strength

fIf[MPa]

fpeak[MPa]

fFt[MPa]

feq(0-0.6)[MPa]

feq(0.6-3)[MPa]

Ft1[MPa]

Ft2[MPa]� D0 D1

R0A - 3.850 3.465 - - - - - -R0B - 4.509 4.058 - - - - - -P1A - 3.716 3.344 - - - - - -

Average - 4.025 3.622 - - - - - -Variation

Coefficient [%] - 10.56 10.55 - - - - - -

S0A 3.899 6.181 3.509 5.559 2.879 2.501 0.189 1.425 0.512S0B 4.350 6.805 3.915 6.063 3.890 2.728 0.581 1.391 0.649S0C 4.736 6.644 4.263 5.600 4.014 2.520 0.747 1.187 0.732S1A 4.334 7.023 3.900 6.216 4.545 2.797 0.874 1.437 0.733S1B 4.231 4.982 3.808 4.623 2.496 2.081 0.208 1.092 0.553S1C 4.195 6.279 3.776 5.602 3.661 2.521 0.570 1.314 0.651S2A 4.575 6.526 4.118 5.825 3.672 2.621 0.526 1.263 0.638S2B 5.003 5.571 4.503 4.920 2.409 2.214 0.097 0.983 0.506S2C 4.131 5.269 3.718 4.650 2.809 2.092 0.358 1.120 0.604

Average 4.384 6.142 3.945 5.451 3.375 2.453 0.461 1.246 0.620Variation

Coefficient [%] 7.69 11.61 7.68 10.79 22.19 - - - -

Material characterization: bending strength

0 1000 2000 3000COD [m]

0

4

8

12

N [M

Pa]

Mean

0 1200 2400 3600COD [m]

0

4

8

12

N [M

Pa]

fctf = 6.09 MPa [s = 0.84]f1tf = 6.10 MPa [s = 0.77]fFtf* = 2.57 MPa [s = 0.79]

P P

l l l

L =3.5 l

h+a=

l

ah

0 1000 2000 3000COD [m]

0

4

8

12

N [M

Pa]

Mean

Mechanical properties according to UNI 11039

SFRC for panels: mechanical tests

Fibre content 50 kg/m3

df = 0.8 mmLf = 60 mm

SFRC Classification

C60–S5–12–XC4–F4–DH1–DS1UNI 11039

4a

fR1k/fLk ≈ 0,94 > 0.4fR3k/fR1k ≈ 0,70 > 0.5

MC 2010 (EN14651)

Prova di flessione a quattro punti

P/2 P/2L/4 L L L L/4

Experimental tests: test set-up

L 1 L 2 L 3

L 4

L 7L 6 L 8

Vert A1 Vert A2 Vert B1 Vert C1 Vert D1 Vert E2 Vert E1

A B C D E

lato 1

Scopo: ottenere dei diagrammi

Experimental tests: test instrumental equipment

L 1 L 2 L 3

L 4

L 7L 6 L 8

Vert A1 Vert A2 Vert B1 Vert C1 Vert D1 Vert E2 Vert E1

A B C D E

lato 1

Experimental tests: test instrumental equipment

Experimental tests: test instrumental equipment

Vert A1 Vert A2 Vert B1 Vert C1 Vert D1 Vert E2 Vert E1

L 7

L 9

L 1

L 3

L 5

L 6

A B C D E

lato 1

Rilievo fotogrammetrico digitale

Experimental tests: reference grid

0 0.004 0.008 0.012 0.016 0.02[1/m]

0

5

10

15

20

25M [kNm]

S0AS0A sxS0BS0C

Carichi pre-esistenti (mezzeria):Momento da peso proprio: 2.46kNmMomento da ripartitore: 1.1kNm

0 4 8 12[mm]

0

10

20

30

40

50P [kN]

S0AS0BS0C

Carichi pre-esistenti (oltre al peso proprio)Carico del ripartitore: 2.2kN

0 0.04 0.08 0.12[1/m]

0

40

80

120

160

200M [kNm]

R0AR0BR0B dx

0 40 80 120[mm]

0

100

200

300

400P [kN]

R0AR0B

SFRC

R/C

Experimental tests: not post-tensioned beams

Midspan loads MG

MQ

Load device = 2.2 kN

0 30 60 90 120[mm]

0

50

100

150

200

250P [kN]

S1AS1BS1C

0 20 40 60 80 100[mm]

0

100

200

300P [kN]

P2AP2B

0 20 40 60 80 100[mm]

0

100

200

300P [kN]

S2AS2BS2C

Calcestruzzo

SFRC

P/C

0 30 60 90 120[mm]

0

50

100

150

200

250P [kN]

P1AP1B

4 strands

5 strands

Experimental tests: post-tensioned beams

0 0.004 0.008 0.012 0.016 0.02[1/m]

0

5

10

15

20

25M [kNm]

S0AS0A sxS0BS0C

Carichi pre-esistenti (mezzeria):Momento da peso proprio: 2.46kNmMomento da ripartitore: 1.1kNm

Experimental tests: not post-tensioned beams

Midspan loads MG

MQ

feq2,m = 3.375 MPas = 0.749 MPafeq2,k = feq2,k – ks = 2.124 MPafFtuk = feq2k/3 = 0.708 MPafFtd = fFtuk/f = 0.708 / 1.5 = 0.47 MPa

fFtd

Mud

Mud = fFtd · b · h2 /2 = 6.34 kNm

Mud

s ~ 2.8

Experimental tests: not post-tensioned beams

fsd

Mrd

Mrd= 144.1 kN m

Mrd

s ~ 1.18

fc1

0 0.04 0.08 0.12[1/m]

0

40

80

120

160

200M [kNm]

R0AR0BR0B dx

Experimental tests: post-tensioned beams

Mrd

Prd= 141.78 kN m

Prd

s ~ 1.13

fc1

0 30 60 90 120[mm]

0

50

100

150

200

250P [kN]

S1AS1BS1C

Np0

fFtd

h/2

h/2

Asse di calcolo

p0= 1350 MPa · 0.8 = 1080 MPaNp0 = 4 · 139 mm2 · 1080 MPa = 600 kNfc1 = 26.56 MPa

x1

x2

fc1 · b · x1 = Np0x1 = 75.30 mm

0.8 · fc1 · b · x2 = fFtd · b · (h-x1-x2)x2 = 4.86 mm

Mrd= 1.24 + 2.25 + 67.4 = 70.89 kNm

1m

Experimental tests: post-tensioned beams

Mrd

Prd= 134.8 kN m

fc1Np0

h/2

h/2

Asse di calcolo

p0= 1350 MPa · 0.8 = 1080 MPaNp0 = 4 · 139 mm2 · 1080 MPa = 600 kNfc1 = 26.56 MPa

x1

fc1 · b · x1 = Np0x1 = 75.30 mm

Mrd= 1.24 + 2.25 + 67.4 = 67.4 kNm

1m

Osservazioni

- livelli prestazionali ben distinti

- rigidezze iniziali

- duttilità

42

374

207

101

0 0.2 0.4 0.6 0.8 [mm]

0

4

8

12

16P [kN]

R0BS1CS0A

0 30 60 90 120 [mm]

0

100

200

300

400P [kN]

R0BS1CS0A

Experimental tests: comparisons

0 30 60 90 120

0

100

200

300P [kN] P2

S2

0 30 60 90 120stroke [mm]

0

100

200

300P [kN] P1

S1

Contributo a trazione

Contributo a compressione

P1B (4 strands - PC)

S1B (4 strands) SFRC)

120 kN

100 kN

Experimental tests: comparisons

• Contributo delle fibre a trazione

• Buona ripetibilità del comportamento degli elementi strutturali

No cracking of ducts!

Experimental results: observation

Geometria della sezione (cls/acciaio)

Discretizzazione della sezione

(solo cls) Legame costitutivo

(cls/acciaio)

Calcolo delle caratteristiche geometriche della sezione

max

yy sup_:)sup,_,(

0:N NtleggeN )cos_,sup,_(

max i

)sup,_(: MM

Diagramma M-

Integrazione numerica

Diagramma P-

ii :

Cross section geometry

Concretediscretization

Constitutive laws

Geometrical characteristic computations

P diagram

Numerical integration

M – diagram

Test modelling: plane section approach

-0.02 -0.015 -0.01 -0.005 0 0.005

300

200

100

0lineadizeroestremisezione0.33·Pu

controllo0.33·Pu

estremisezione0.66·Pu

controllo0.66·Pu

estremisezione0.9·Pu

controllo0.9·Pu

y[mm]

tension compress.

Pu/32Pu/3

0.9Pu

σFt2=0.5feq2 - 0.2feq1

σ

wwi1 wi21.5

fctm

ε (x10-4)

σ

0.9fctm

1

Ec

fctm

σFt1=0.45feq1

w1 wc

ε

fc

13 fc

αc/3

Gc

h

αc αu

Feenstra

Sargin

σ

Test modelling: uniaxial constitutive relationships

0 0.02 0.04 0.06

0

400

800

1200

1600

2000

[MPa]

steel

Model Code 90

= 0.83

0 0.005 0.01 0.015 0.02 0.025[1/m]

0

5

10

15

20

25M [kNm]

sperimentaleteorico

Carichi pre-esistenti (mezzeria):Momento da peso proprio: 2.46kNmMomento da ripartitore: 1.1kNm

0 0.005 0.01 0.015 0.02 0.025[1/m]

0

5

10

15

20

25M [kNm]

sperimentaleteorico

Carichi pre-esistenti (mezzeria):Momento da peso proprio: 2.46kNmMomento da ripartitore: 1.1kNm

0 0.005 0.01 0.015 0.02 0.025[1/m]

0

5

10

15

20

25M [kNm]

sperimentaleteorico

Carichi pre-esistenti (mezzeria):Momento da peso proprio: 2.46kNmMomento da ripartitore: 1.1kNm

S0A S0CS0B

105 34 43 28

n° fibre e n° buchi nella sezione di rottura S0A

73

110 42 37 31

195 70 52

132410 146 132 334 104 119

n° fibre nella sezione di rottura S0B

111 25 35 50

41

112 40 52 20

111 38 32

111

31 46

n° fibre nella sezione di rottura S0C

104 22 40 42

119

48

95 29 37 29

324 82 123

125

exp.th

Fibre number in failed cross section Fibre number in failed cross section Fibre number in failed cross section

exp.th

exp.th

S0A S0B S0C

Test modelling: SFRC beams without long. reinforcement

Test modelling: FE approach

S2C

(-21 % on fIF; -41% on feq(0-0.6); -43% on feq(0.6-3))

Test modelling: FE and PS approach comparison

0 2 4 6 8m [mm]

0

10

20

30

40

50P

[kN]

S0CExp.PS NLFEA

0 20 40 60 80 100m[mm]

0

100

200

300

P [kN]

S1CExp.PS-variable strand tensionPS-constant strand tensionNLFEA-homogeneous materialNLFEA-defect

Test modelling: multicracking by FE approach

0 20 40 60 80 100m[mm]

0

100

200

300

P [kN]

S1CExp.PS-variable strand tensionPS-constant strand tensionNLFEA-homogeneous materialNLFEA-defect

Test modelling: multicracking by FE approach

0 20 40 60 80 100m[mm]

0

100

200

300

P [kN]

S1CExp.PS-variable strand tensionPS-constant strand tensionNLFEA-homogeneous materialNLFEA-defect

Monitoring of retaining structure

Vibrating wires (CV), optic fibres (F) and loading cells positions

Monitoring of retaining structureLoad vs. strand sliding

Which load duringground anchor post-tensioning?

Meteo conditions

Rainfalll

Temperature

winter summer

Temperature evolution

EDL

EDR

EUL

EUR

Long term monitoring of load cells

Load cell single strand

RESEARCH FRAMEWORK

A.C.C.I.DE.N.TFunded by INTERREG

Advanced Cementitious Composites In DEsign and coNstruction of safe Tunnel

Original design

Plizzari et al., 2008advantages: less space, easier construction, simpler mounting

Tunnel lining design

0

1

2

3

4

5

6

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0CMOD [mm]

Nom

inal

str

ess

[MPa

]

CM

OD

1

CM

OD

2

CM

OD

3

CM

OD

4

fR1 fR2 fR3

fR4

Type A

Type C

Type B

PANAMA tunnel

courtesy by Meda, 2012

SFRC

HPFRCC

Tunnel Segment Design : materials used and investigated

DAMPING MATERIAL

TRM

600 °C400 °C200 °C20 °C

COD [mm]9876543210

30

27.5

25

22.5

20

17.5

15

12.5

10

7.5

5

2.5

0

SFRC in uniaxial tension

HPFRCC in bending

N[Mpa]

TRMDamping in compression

Tunnel Segment Design - Costs

MATERIAL UNIT COST VOLUME TOTALCONCRETE

C40/50100 € /m3 1.34 m3 134 €

STEEL REINFORCEMENT 0.9 € /kg 120 kg/ m3 145 €

279 €

MANUFACTURE 25 % - 70 €

TRADITIONAL SOLUTION

MATERIAL UNIT COST VOLUME TOTAL

HPFRCC (borders) 430 € /m3 0.29 m3 125 €

SFRC 150 € /m3 1.05 m3 158 €

TRM 3 € /m2 4.48 m2 13 €

STEEL REINFORCEMENT 0.9 € /kg 35 kg/ m3 43 €

339 €

MANUFACTURE 25 % - 70 €

INNOVATIVE SOLUTION

350 €

410 €

+ 17% TOTAL COST

- 71% steel reinforcement

= 21% of trad. material cost for manufacture

Tunnel Segment Design - Structural design model

Two half rings with masonry layout

Hinged beam to represent segment

Rotational spring for longitudinal joints

Shear spring for circumferential joint

Radial and tangential springs for soil

MODEL PARAMETERS

N. of element per segment: 12

N. of element per k-segment: 4

Length of beam elements: 0.2945 m

Total N. of elements: 128

MODEL ASSUMPTIONS

Ring type: 5 + 1

External radius: 3.15 m

Segment thickness: 0.3 m

Segment width: 1.5 m

Segment length: 3.534 m

GeometryJoints

Production of segments

THANKS FOR YOUR ATTENTION!