IS-BETON

Jörg Jungwirth Poster n° 339

Structural Behavior of Tension Members in Ultra High Performance ConcreteImprovements in the concrete mix design, along with the addition of metallic fibers, have lead to a new high performance cement material known as Ultra High Performance Concrete. A Compression resistance about 150 - 250 MPa and a reliable tension resistance can be achieved.The high performance concrete project currently under way at the Structural Concrete Laboratory (IS-BETON) aims at examining new concept and design approaches to design statically efficient and economically viable structures using UHPC. In this scope a study on the tensile behavior of UHPC has been conducted. Material tests and tests on structural members with reinforcement bars have been performed. A schematic representation of the material behavior allows a general description of the behavior of structural members in tension.

0

2

4

6

8

10

0 1 2 3 4ε [‰]

σ [N

/mm

2 ]

specimen 3without fibers

specimen 2

specimen 1

0

2

4

6

8

10

12

0.0 0.5 1.0 1.5 2.0∆ l [mm]

σ [N

/mm

2 ]

u [mm]0.0 1.51.00.5

specimen 5

specimen 6

specimen 4

0

2

4

6

8

10

12

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

ε [ ‰ ]

σ [N

/mm

2 ]

u [mm]0.0 1.51.00.5

f ct.matrix l

Phase 1

l ∆l

s r

Phase 2

1

3

2

E matrix

u

( , , , )ct f f f ff f lρ τ=> ∅

l

u

Phase 3

E *

*l u lEσ

∆ = +

Material Behavior

Dis

tribu

ted

Def

orm

atio

nC

rack

O

peni

ng

Tens

ile b

ehav

ior o

f an

UH

PC

ele

men

t

Testing of Tension Members

-

4.1%

2.5%

1.0%-

[%]ρ

10626004∅15.2FpT5

69812564∅20Fs >> FcT4

4478044∅16Fs > FcT32514524∅12Fs ≈ FcT2

---Fs = 0T1[kN][mm2][mm2]FsAsChosenCriterion

Tension Behavior

Test

Set

upfo

r ten

sion

test

s on

st

ruct

ural

mem

bers Te

stPa

ram

eter

sC

rack

ing

Beha

vior

Ope

ned

Cro

ss S

ectio

n

48.035.525.918.6

-[MPa]

ft

6.728.48.69

[MPa]fct=ft – Fs/A

38.511.210.910.5

7.8(?)[MPa]fCrack

12.510624∅15.2T512.5606984∅20T412.5504474∅16T312.5402514∅12T212.5--T1[mm][mm][kN][mm2]

sCrack,finesCrackFsReinforcement

Directeur de thèseProf. A. Muttoni

LiteratureJungwirth J., Muttoni A., Structural Behavior of

Tension Members in UHPC, EPFL-IS-BETON, Lausanne, 2004

Jungwirth J., Muttoni A., Versuche an Bauteilen aus ultrahochfesten Beton – Teil 1 Material, EPFL-IS-BETON, Lausanne, 2004

Jungwirth J., Muttoni A., Versuche an Bauteilen aus ultrahochfesten Beton – Teil 2 Bauteile, EPFL-IS-BETON, Lausanne, 2004

Plumey S., Jungwirth J., Muttoni A., Comportement des éléments en béton à ultra hautes performances, EPFL-IS-BETON, Lausanne, 2002

http://is-beton.epfl.ch/Person/Jungwirt/

Res

ults

of t

he te

nsio

n te

sts

on

stru

ctur

al m

embe

rs

Mod

el fo

r ten

sion

test

s on

stru

ctur

al

mem

bers

Sponsored by:

0

20

40

0 5 10strain (l 0 =1m) [‰]

nom

inel

stre

ss N

/Ato

t [M

Pa]

ρ = 1%4∅12

reinforcement4∅20

ρ = 0%

reinforcement4∅12

reinforcement4∅16

ρ = 2.5%4∅16

ρ = 4.1%4∅20

T1

T2

T3

T4

f Crack

f t

f ct

0

25

50

0 5 10strain (l 0 =1m) [‰]

nom

inel

stre

ss N

/Ato

t [M

Pa]

4Τ15S1770σPo = 0.7ftk

ρ = 2.5%4∅16

T3

T5

0

5

10

15

20

25

30

0 2 4 6 8 10strain (l 0 =1m) [mm/m]

nom

inal

stre

ss N

/Ato

t [M

Pa]

ρ = 0%calculated (see material behavior)

steel4∅16

calculatedρ = 2.5%

testingρ = 2.5%

behavior of ordinary reinforced concrete with ρ = 2.5%

T3

Measured characteristic values:fct,Matrix = 8.9 MPafct = 9.7 MPaE = 60 GPa