Sustainable Roof elements: a proposal offered by ... · uplifting device Polystyrene TRM HPFRCC • small weight (about 70 kg/m 2) • high quality finishing Main advantages P (kN)

ACES Workshop: Innovative Materials and

Techniques in Concrete ConstructionHoliday Palace Hotel, Corfu (GR) - October 10-12, 2010

Sustainable Roof elements:

a proposal offered by cementitious

composite technology

M. di Prisco, A. Caverzan, L. Ferrara, M., A. Magri, G. ZaniPolitecnico di Milano, Department of Structural Engineering

� research significance

� material properties

Outline

� material properties

� sandwich plates: test results

� open problems

� concluding remarks

M. di Prisco, A. Caverzan, L. Ferrara, M., A. Magri, G. Zani

uplifting device

TRMPolystyrene

HPFRCC

• small weight (about 70 kg/m2)

• high quality finishing

Main advantages P (kN)

2.5 m

1.25 m

P P

6

δ

4


• high quality finishing

• good fire resistance

• high insulation

• no need of waterproofing layer δ (mm)9 36

6040

4

Dosage (kg/m3)

Cement type I 52.5 600

Slag 500

Water 200

Table 1 Composition of mix

HPFRCC material

Water 200

Superplasticizer 33 (l/m3)

Sand 0-2 mm 983

Fibers (lf = 13mm;

df = 0.16mm)100 730-800 mm

> 750 mm

γ = 2450 – 2530 kg/m3

R = 66.3 Mpa


Rcm, 24h = 66.3 Mpa

Rcm, 7d = 99.1 Mpa

Rcm, 28d = 116.5 Mpa

Esm = 45249 Mpa

5EXPERIMENTAL PROGRAM : MANUFACTURING


40 mm

30 mm

Temperature exposure2h

12°C/h


30°C/h in the heating process

7Bending tests on unnotched flow-oriented fibres specimens

600 °C400 °C200 °C20 °C

N[MPa]

30

27.5

25

22.5

20

17.5

15

12.5


COD [mm]

σN[M

9876543210

12.5

10

7.5

5

2.5

0

Polystyrenemortar

F

δ1,δ2 δ3,δ4

60

20

A A


F

Spacing

[mm]

Weight

[g/m2]

Failure load

[N/m]

Max elongation

[%]

Gross

mesh

Coated

mesh

Warp Weft Warp Weft

4.5x5.0 125±5% 155±5% 40000 46000 4.5±1 4.5±1

TRC

AR Glass fabric


dg,max = 0.6 mm

Two overlapped layers

0.6 mm

P (N)70 mm

10


δ (mm)

ρgf ~ 5%

Pcr,th= 3.5 kN

25

AR Glass Fabric

Textile Reinforced Concrete Under static loading

Courtesy by Alva Peled

10

15

20

nsi

le S

tres

s, M

Pa

AR Glass FabricVf = 4.5%

GFRC Vf =5%

Short glass fibers

Tensile static test


0 0.01 0.02 0.03Strain, mm/mm

0

5Ten

Fabrics exhibit:

• high resistance under static

loading

• multiple cracking with small

opening

Plain matrix

Cement

Composite

laminates board

Squeezed

rollers

Fabric

locationPultrusion Technology

Cement

bath


Peled & Mobasher, 2003

Full Scale Structural Tests



P (kN) P (kN)


δ (mm) δ (mm)

P (kN)M

(kNm)

P (kN) P (kN) P (kN)

δ (mm) θ (mm-1)*10-5


δ (mm)

δ (mm) δ (mm)

M(kNm/m)

sandwich plate

sandwich beam

M(kNm/m)

UHPFRC plate

sandwich plate


θθθθ (mm-1)*10-5 θθθθ (mm-1)*10-5

Technological and design problems

• fiber orientation is a technology in progress (large

scattering in the bending response) scattering in the bending response)

• production of suitable AR glass fabrics is in progress

• polystyrene could be substituted by other materials with

better energy performance

• which design parameters for UHPFRC (SLS and ULS)?

• which characteristic length for Textile?


• which characteristic length for Textile?

• which model to predict the experimental behavior?

beam

T2

beam

T1

50 150150150 500

beam L2

beam L1 015

015

050

casting

direction

T1-BT2-B

T1-AT2-A L1-A

L2-AL2-B

L1-B

10

15

20

25

[MPa]

beam L1

150

supposed flow lines

T1-AT2-A L1-AL1-B

Slab A

20

30

mm

2)

beam L1

beam L2

500 mm - 20 in.

150 mm - 6 in.

200 mm - 8 in.

A

A sect. A-A

150 mm

6 in.

30 mm - 1.2 in7 mm

0 1 2 3

0

5 20° C

20° C av

3.6

COD [mm]


0 2 4 6 8 10

COD (mm)

0

10

σN (N

/m beam L1

beam T2

beam T1

450 mm - 18 in.

200 mm - 8 in.

σ

0.9 fIf/β

σN,peak/β1

arctg E

25+2h0.7

2h0.7

Ec = 22000 (fc/10)0.3 = 43600 N/mm2

for fc = 96 N/mm2

= 2.16 (for h = 30 mm)β =

ε

M = σN,peak bh2/6

σ

εpeak σpeak

0.9fIf/β

Εχx

χ

x

500 mm - 20 in.

150 mm - 6 in.

450 mm - 18 in.

200 mm - 8 in.

A

A

7 mm

σ

σN, peak

κ1 feq,2 0.10

ε

M = feq (0.1h) bh2/6σ(0.02)

σσpeak

Compression

force0.02

σ(0.10)

β1

ε

M = feq2 bh2/6

σ(0.02)

σ

0.02

σpeakχ

x Εχx

12

16

mm

2)

beams L1/2

slab A

DEWS L1/2-B

12

16

mm

2)

beams L1/2

slab A

DEWS L1/2-B

εεpeak = CMODpeak

lCOD

arctg Ec

for fc = 96 N/mm

crack opening w0.02 h

κ2 feq, wu

wu = 0.10 h


0 0.002 0.004 0.006 0.008 0.01

strain ε

0

4

8

σ (N

/m

arctg Ec

DEWS T1/2-B

0.6 3

crack opening w (mm)

0

4

8

σ (N

/m

0 3 6 9

DEWS T1/2-B

Standard specimen test

UNI 11039PIf

U2U1

P

CTOD

P’F

l/2 l l/2l l

45

mm l

l

l=150 mm

l

CTOD0 CTOD0+3mm CTODCTOD

[mm]+0.6 + 3.0


fIf ,av = 7.10 Mpa

feq 0-0.6 = 12.06 Mpa

feq 0.6-3 = 9.76 Mpa

22STATE OF ART: THE MATERIAL

HPFRCC at low strain rates


� small specimens tested

� increasing the specimen size the material homogeneity decrease

� A standard does not

The ultimate tensile strength fFtu in the linear model depends on

the required ductility that is related to the allowed crack width.

Ultimate COD condition: a ductility requirement

The ultimate crack width can be calculated as

wu = lcs * εεεεFu

by assuming εFu equal to 2% for variable strain distribution

along the cross section and 1% for only tensile strain

distribution along the cross section.


distribution along the cross section.

The max. crack width may not exceed 2.5 mm.

wu* = (0.02 - εpeak) *h + εpeakLCOD

24TEST RESULTS: RESIDUAL STRENGTHS

Temperature [°C]

Sample number

fIf [MPa]fIf,av[MPa]

(std)feq1

[MPa]feq1,av[MPa]

(std)feq2

[MPa]feq2,av[MPa]

(std)

20 1 11.5011.30(0.35)

16.4115.98(0.46)

22.5422.81(0.39)

20 2 11.50 15.50 23.26

20 3 10.90 16.02 22.63

200 1 9.51 17.46 23.29


200 1 9.519.10

(0.36)

17.4617.37(0.22)

23.2923.42(0.47)

200 2 8.91 17.12 23.94

200 3 8.88 17.53 23.02

400 1 5.544.93

(0.53)

15.0313.97(0.93)

21.9223.23(1.92)

400 2 4.65 13.53 25.44

400 3 4.59 13.35 22.31

600 1 4.784.64

(0.19)

13.6113.16(0.47)

3.644.36

(1.36)600 2 4.72 13.20 3.51

600 3 4.42 12.67 5.92

25Interpretazione dei risultati

1. Imbarcamento dei provini dovuto a fenomeni di ritiro plastico

2. Effetto dimensionale


3. Presenza di difetti

σS

p=

6m

m

A

A

Sezione AA

26Interpretazione dei risultati

4. Fenomeni di scorrimento del rinforzo


exp.

model Which characteristic length

for TRC material?

� weft spacing� weft spacing

� layer thickness

� is it variable?


Which models ?

Plane section

exp. results (average)

exp. results (envelope)

M(kNm/m)


exp. results (average)


FE model (ch. length = 400 mm)M(kNm/m)

θθθθ (mm-1)*10-5


UHPFRCC elements

Polystyrene elements

TRC elements

FE model (ch. length = 400 mm)

FE model (ch. length = 400 mm)

M(kNm/m)

θθθθ (mm-1)*10-5

Concluding Remarks

•� Light and sustainable roof elements can be produced

and they improve fire resistance and lightness with and they improve fire resistance and lightness with

reasonable costs;

� structural specimen is needed to characterize thin

structural elements, but DEWS tests allows the use of

compression test to identify softening behavior in

uniaxial tension and characterize material orthotropy;

� TRC can be improved in order to increase the total


� TRC can be improved in order to increase the total

load at SLS: its characteristic length has to be identified

� plane section model seems able to fit reasonably

experimental results, while FE model requires further

improvements

ThankThank youyou forfor youryour attentionattention!!


Documents

Sustainable Roof elements: a proposal offered by ... · uplifting device Polystyrene TRM HPFRCC • small weight (about 70 kg/m 2) • high quality finishing Main advantages P (kN)