Scott Munter Scott Munter –– Steel Reinforcement Institute

Scott Munter Scott Munter –– Steel Reinforcement Institute of AustraliaSteel Reinforcement Institute of AustraliaMarkMark PatrickPatrick –– MP EngineersMP EngineersMark Mark Patrick Patrick –– MP EngineersMP Engineers

Vijay Rangan Vijay Rangan –– Curtin University of TechnologyCurtin University of Technology

New Design Rules in AS 3600 2009Overview

New Design Rules in AS 3600–2009 Straight D500N bars Tensile development lengths Tensile lap lengthsp g

Recent Australian Bond Test Series University of New South Wales University of Queensland Curtin University of Technology (SRIA)

A t li B d T t R lt Australian Bond Test Results

New Design Rules in AS 3600–2009 D500N Bars to AS/NZS 4671

Stress

Tensile Strength fu(Onset of Necking)Tensile-to-yield-stress

ratio fu /fsyStress u sy

Yieldstress

Uniformstrain

stress fsy Fracture

u

Strain

New Design Rules in AS 3600–2009 D500N Bars to AS/NZS 4671

Property D500N

D500N Bars to AS/NZS 4671

Nominal diameter (mm) 10 to 40

Characteristic yield stress (MPa)Characteristic yield stress (MPa)

lower 500

upper 650

Tensile-to-yield-stress ratio min 1 08Tensile-to-yield-stress ratio, min. 1.08

Uniform strain (%) , min. 5.0 DUCTILITY

PARAMETERS

Estimate upper characteristic tensile strength = 1.15x650 = 750 MPa = 1.5fsy

Basic Tensile Development Length:New Design Rules in AS 3600–2009

1 d b b sy b50 1.0 0.15( /29

k c d d f dL k d

Basic Tensile Development Length:

c2

sy.tb 1 b

b c

29(132 )

L k dd f

acd = min. (c1, c2, a/2)

and db cd 3db c1

R fi d T il D l t L thRefined Tensile Development Length:

3 sy.t tr tr.min s p sy.tb sy.tb[1.0 ( ) / ] [1.0 0.04 ] (0.7/ )L K A A A L k L3 sy.t tr tr.min s p sy.tb sy.tb

Transverse reinforcement Transverse pressureterm, k4 term, k5

Basic Tensile Lap Length:New Design Rules in AS 3600–2009

1 d b b sy b50 1.0 0.15( /29

k c d d f dL k k d

Basic Tensile Lap Length:

a c2

7

sy.tb.lap 1 b

b c

29(132 )

L k k dd f

cd = min. (c1, c2, a/2)and db cd 3db c1

R fi d T il L L thRefined Tensile Lap Length: sy.t.lap tr tr.min s p sy.tb.lap 3 sy.tb.lap 1 b[1.0 ( ) / ] [1.0 0.04 ] max.[(0.7/ ) ,29 ]L K A A A L k L k d sy.t.lap tr tr.min s p sy.tb.lap 3 sy.tb.lap 1 b

Transverse reinforcement Transverse pressureterm, k4 term, k5

New Design Rules in AS 3600–2009

What minimum tensile stress should anchored or spliced bars be capable ofanchored or spliced bars be capable of

reaching before failure occurs?

In design it is assumed that the nominalIn design, it is assumed that the nominal yield stress, fsy=500 MPa, will be reached b f th h li f ilbefore the anchorage or splice fails…....

but what about in the real structure?


Clause 13.2.6 Welded or mechanical splices

“Welded or mechanical splices formed between Class N reinforcing bars shouldbetween Class N reinforcing bars should

not fail prematurely in tension or compression before the reinforcing barscompression before the reinforcing bars, unless it can be shown that the strength

d d tilit f th t b tand ductility of the concrete member meet the design requirements.”


A f f li d b t th Any form of splice can reduce bar strength


600

700

Diameter f u uMPa %

400

500

Pa)

Diameter f u u

Control 664 10.015.1 620 4.514 8 607 3 5

MPa %

300

400

Stre

ss (M

P 14.8 607 3.514.5 590 2.013.9 550 0.8

200

S 13.9mm notch diameter14.5mm notch diameter14.8mm notch diameter15.1mm notch diameter

0

100

0 2 4 6 8 10 12 14

Control Bar – N16

0 2 4 6 8 10 12 14

Strain (%)

700Design principles

600

400

500

MPa

) ACI 318 – 08 Non-seismic1.25 x 500 = 625 MPa

300

Stre

ss (M 1.25 x 500 625 MPa

100

200

0

100

0 1 2 3 4 50 1 2 3 4 5

Strain (%)

Recent Australian Bond Test Series

U i it f N S th W l University of New South Wales

• 10 conventional slabs in flexure

• Small diameter, widely-spaced D500N12 or N16 barsD500N12 or N16 bars representative of slabs or walls (min. clear distance 157 mm)

• No staggering

• No transverse reinforcement

• Short lap length (max. approx. 18db) for bond failure


U i it f Q l d University of Queensland

U ti l ll t t t• Unconventional pull-out tests,

without flexure to cause bar

prying, etc.

• Small diameter D500N16 bars• Small diameter, D500N16 bars

representative of slabs or walls

• Contact lap splices

• No staggering• No staggering

• Transverse bars present in 3 of

these tests, but presence should

be ignored in design since onbe ignored in design since on

wrong side of main bars


C ti U i it f T h l SRIA t t Curtin University of Technology – SRIA tests

200TYPICAL

138TYPICAL

300

62

N24

900

4 N24 contact lap spliceswithout transverse reinforcement



4500

125TYPICAL 1375

900

300

1500

Test lap length =900 mm, while AS 3600–2009 design L 930 if i l f' d k 1 0Lsy.tb.lap = 930 mm if use nominal f'c and k7=1.0





Face splitting & Edge side splittingFace splitting & Edge side splitting





150TYPICAL

75TYPICAL

30051 TYPICAL

N24

900

62

6 N24 contact lap spliceswithout transverse reinforcement





Side splitting



Bar prying

Australian Bond Test Results

A i C t I tit t (ACI) D t b American Concrete Institute (ACI) Database3.0

ss -08

2.5

mat

e B

ond

Stre

s

5 f sy

AC

I 318

-

1.5

2.0

009

Des

ign

Ulti

m

ACI 408

1.2

1.5fsy bar fracture

1.0

ess

/ AS

3600

-20

1.25 fsy AS 3600-2009

0.5

timat

e B

ond

Stre

0.00.0 0.5 1.0 1.5 2.0 2.5 3.0

Ult

Ultimate Bond Stress / ACI 318-08 Design Ultimate Bond Stress


A i C t I tit t (ACI) D t b American Concrete Institute (ACI) Database

90

ACI DATA BASE ‐ BOTTOM BARS, NO TRANSVERSE REINFORCEMENT

70

80

600-

2009

1.5fsy bar fracture

50

60

ency

1.25

f sy

AS

36 1.5fsy bar fracture

30

40

Freq

ue 1

5% Failure Rate

10

20

5% Failure Rate

0

0.063 0.188 0.313 0.438 0.563 0.688 0.813 0.938 1.063 1.188 1.313 1.438 1.563 1.688 1.813 1.938 2.063 2.188 2.313 2.438 2.563 2.688 2.813 2.938 More

Ultimate Bond Stress / AS 3600‐2009 Design Ultimate Bond Stress


U i it f N S th W l University of New South Wales3.0

ss -08

2.5

mat

e B

ond

Stre

s

25 f s

yA

CI 3

18 1.5fsy bar fracture

1.5

2.0

009

Des

ign

Ulti

m

ACI 408

1.2

1.0

ress

/ AS

360

0-20

UNSW

1.25 fsy AS 3600-2009

0.5

timat

e B

ond

Str

0.00.0 0.5 1.0 1.5 2.0 2.5 3.0

Ult



U i it f Q l d University of Queensland3.0

s -08

2.5

mat

e B

ond

Stre

s

5 f sy

AC

I 318

-

1.5fsy bar fracture

1.5

2.0

009

Des

ign

Ulti

m

ACI 408

1.25

1.0

ess

/ AS

3600

-20

UNSW

UQ

1.25 fsy AS 3600-2009

0.5

imat

e B

ond

Stre

0.00.0 0.5 1.0 1.5 2.0 2.5 3.0

Ulti



C ti U i it f T h l SRIA t t Curtin University of Technology – SRIA tests3.0

ess

8-08

2 0

2.5

mat

e B

ond

Stre

ACI 40825 f s

yA

CI 3

18

1.5

2.0

2009

Des

ign

Ulti ACI 408

UNSW

1 25 f AS 3600 2009

1.2

1.0

ress

/ AS

360

0-2

UQ

CUT - SRIA (4 bars)

1.25 fsy AS 3600-2009

0.5

ltim

ate

Bon

d St

CUT - SRIA (6 bars)

0.00.0 0.5 1.0 1.5 2.0 2.5 3.0

U


Bond Test Results & Conclusions

UNSW & UQ tests were designed to replicate slabs & walls incorporating small diameter bars (D500N12 & 16)

Results of UNSW and UQ tests on small diameter (N12 & Results of UNSW and UQ tests on small diameter (N12 & N16) bars, with very high mean AS 3600–2009 test/design ratios of 2.1fsy and 1.8fsy,respectively, indicate that factor k =(132 d )/100 could possibly be increasedk2=(132-db)/100 could possibly be increased

SRIA tests on beams with D500N24 bars performed by Curtin University also indicate 1.25fsy is more realisticsy

ACI database shows that 1.25fsy is a much more realistic target achieved using AS 3600–2009 under non-seismic conditions which serves as a ductility criterion for splicedconditions, which serves as a ductility criterion for spliced D500N bars generally

Scott Munter Scott Munter –– Steel Reinforcement Institute of AustraliaSteel Reinforcement Institute of AustraliaMarkMark PatrickPatrick –– MP EngineersMP EngineersMark Mark Patrick Patrick –– MP EngineersMP Engineers

Vijay Rangan Vijay Rangan –– Curtin University of TechnologyCurtin University of Technology

Documents

Scott Munter Scott Munter –– Steel Reinforcement Institute