2012/12/20
Construction Standard
New Steel Reinforcement
Standard CS2:2013
A Laboratory Perspective
CS2:2012
CS2:2012 (rev. H)
Steel Bars for the
Reinforcement of Concrete
Ir C K Cheung
Hong Kong Concrete Institute
香港特別行政區政府
The Government of the Hong Kong Special Administrative Region
CS2:2012 Rev. H
Reinforcing Steel Bar Properties
• Strength
- discharge load bearing function
• Ductile
- bending into shape
- exhibit progressive failure
• Weldability
- welded prefabrications
- on-site welding
• Rib Geometry
• Fatigue
- bonding with concrete
- structures of sophisticated design
•
•
•
•
Reference to
BS4449:2005
BS4449:2009 (Amendment 2)
For ribbed steel reinforcing bars
• BS4482:2005
• For plain steel reinforcing bar up to 12mm
diameter
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2012/12/20
Why not to BS EN 10080:2005
• It does not define steel grades or
technical classes
• It requires technical classes should be
defined by specified values of Re,
Rm/Re, Agt, fatigue strength, bend
performance, weldability, bond strength,
tolerances and dimensions to National
Standard e.g. BS4449:2005
EN 10080 does not include all the
requirements to fully specify reinforcing
steels. It is intended that EN 10080 should
be used in conjunction with a Technical
Specification, in which the details of the
performance characteristics are specified.
Within the UK, three standards have been
revised for use with EN 10080, these are:
—BS4449:2005,
Steel
for
the
reinforcement of concrete — Weldable
reinforcing steel — Bar, coil and decoiled
product — Specification
—BS4482:2005, Steel wire for the
reinforcement of concrete products —
Specification
—BS4483:2005, Steel fabric for the
reinforcement of concrete — Specification
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2012/12/20
CS2:2012 Stage 1
QA Stockists
Full material specifications
Grade 250 plain steel rebar to 12mm
Grade 500B and 500C ribbed steel rebar
Local requirements for Quality Assured
Stockist
• Purchaser test upgraded by deleting Class
3 steel rebars
• Certified to the BSI QA System for Registered
Stockists is no longer applicable
• QA Stockists are now required to be certified to
the requirements of ISO 9001 by a certification
body accredited by HKAS with a SCOPE related
to good practices on storage, handling and
supply of steel reinforcing bars in accordance
with the specific requirements stipulated in this
Construction Standard.
QA Stockists
Clause 4.2 of the CS2:2012
•
•
•
•
• QA Stockists are also required to
implement specific control on
non-conforming products
• Certification requirements for QA Stockists
shall include procedures on handling of
non-conforming products for all classes of
steel reinforcing bars and
• as stated in Clause 4.2 of the CS2:2012
• maintenance of product traceability from
the QA Manufacturer to the delivery site
for Class 1 steel reinforcing bars.
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2012/12/20
Certification requirements for
QA Stockists (1)
• (a) The customer who has purchased the nonconforming steel reinforcing bars is notified of the
corrective action to be taken including details of
disposition on the non-conforming steel
reinforcing bars.
• (b) The non-conforming steel reinforcing bars
arising from (a) above shall not be sold, supplied
and/or used as conforming steel reinforcing bars of
the original grade.
Purchasers Testing
• In this CS2:2012 bend test is no longer
required.
• Determination of mass per metre is
explicitly required as one of the
purchaser’s tests since control on mass
within permissible deviations is crucial.
Certification requirements for
QA Stockists (2)
• (c) Records of the above (a) and (b) are to be
kept as Quality Records.
• (d) For Class 1 steel reinforcing bars,
acceptable measures such as proper fixing of
the manufacturer’s product traceability tags to
steel reinforcing bars shall be taken throughout
the handling, storage and delivery processes to
prove product traceability.
CLASSIFICATION
• All steel reinforcing bars shall be manufactured by
QA Manufacturers, and handled by
QA Stockists throughout the supply chain, and
shall be classified as follows:
• Class 1 steel reinforcing bars
• Steel reinforcing bars that are fully traceable to
their manufacturer and production data.
• Class 2 steel reinforcing bar
• Steel reinforcing bars that are traceable to their
manufacturers and production data except their
heat /cast numbers.
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2012/12/20
TABLE 10: No. of test specimens per batch
Purchaser’s tests
•
•
•
•
•
•
1. Mechanical properties –
(a) Tensile – Yield, Tensile/Yield ratio, Agt
(b) Rebend
(c) Mass per metre
2. Chemical composition for 10 elements
3. Bond strength and Surface Geometry
Construction Standard CS2:1995
Class 1
Description
Size of batch
0 - 60 tonnes
Tensil Reben Mass per
e
d
metre
3
1
3
Class 2
Chemical
composit
Bond
ion
property
(product
analysis)
1
1
Steel reinforcing bar each
nominal size 6 mm - additional
16 mm
60 tonnes or
part of
60 tonnes
1
Nil
1
Nil
Nil
0 - 80 tonnes
3
1
3
1
1
Steel reinforcing bar
nominal size 20 mm each
additional
- 32 mm
80 tonnes or
part of
80 tonnes
1
Nil
1
Nil
Nil
0 - 100 tonnes
3
1
3
1
1
Steel reinforcing bar each
nominal size
additional
exceeding 32 mm
100 tonnes or
part of 100
tonnes
1
Nil
1
Nil
Nil
Size of batch
Tensil Reben Mass per
e
d
metre
Chemical
composi
Bond
tion
property
(product
analysis)
0 - 35 tonnes
3
1
3
1
1
each additional
35 tonnes or
part of
35 tonnes
3
Nil
3
Nil
Nil
0 - 45 tonnes
3
1
3
1
1
each additional
45 tonnes or
part of
45 tonnes
3
Nil
3
Nil
Nil
0 - 55 tonnes
3
1
3
1
1
each additional
55 tonnes or
part of
55 tonnes
3
Nil
3
Nil
Nil
Purchasers Testing (batch)
• The meanings of “batch” of steel
reinforcing bars for manufacturers testing
and for purchasers testing are also
defined in order to ensure that sampling
of test specimens is conducted in a
consistent manner.
Class 1: QA Producer + QA Stockist + Lot traceable
Class 2: QA Producer + QA Stockist + Lot not traceable
Class 3 : Not Class 1 or Class 2
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2012/12/20
What is a “Purchaser Batch”
What is a “Plant Batch”
• For purchaser testing, the quantity of steel
rebars delivered to site within a week under one
delivery order, of one nominal diameter, and
one steel grade and produced by the same
manufacturer.
• A batch shall not exceed 200 tonnes for steel
reinforcing bars of diameter 20 mm and above
and shall not exceed 100 tonnes for steel
reinforcing bars of diameter less than 20mm.
• For manufacturers testing, a batch is the
quantity of steel reinforcing bars of one nominal
diameter and one heat/cast produced by one
manufacturer and presented for examination at
any one time.
• What is a “Heat/Cast” - an identifying number
assigned to the product of one melting in a steel
production furnace.
Table 2: Range of
Nominal Diameter
• Range of nominal
diameter
• 6, 8, 10, 12, 16,
• 20, 25, 32, 40
• and 50 mm
• 6 and 50 mm nonpreferred diameter
Determination of mass per metre
• The percentage deviation from nominal mass per
metre of the test specimen shall be determined
from the difference between the actual mass per
metre of the test specimen deduced from its
mass and length and nominal mass per metre
as given in Table 2.
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2012/12/20
Table 2- Nominal cross-sectional area &
Nominal mass per metre
Nominal diameter,
d
(mm)
Nominal crosssectional area, An
(mm2)
Nominal mass per metre
(kg)
6a
8
10
12
16
20
25
32
40
50a
28.3
50.3
78.5
113.1
201.1
314.2
490.9
804.3
1256.6
1963.5
0.222
0.395
0.617
0.888
1.579
2.466
3.854
6.313
9.864
15.413
Table 5- Characteristic tensile
properties
Yield strength,
Re
Grade
(MPa)
Tensile/yield
strength ratio,
Rm/Re
Table 3: Permissible deviation
from nominal mass/metre
Grade
250
500B
500C
Permissible
Nominal diameter,
deviation from
d
nominal mass per
metre run
(mm)
(%)
d>8
4.5
d8
6.0
Construction Standard CS2 : 1995
Total elongation
at maximum
force, Agt
(%)
BD’s Reinforced Concrete Code
250
250
1.15
5.0
500B
500
1.08
5.0
500C
500
1.15 and <1.35
7.5
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2012/12/20
PERCENTAGE TOTAL ELONGATION AT
MAXIMUM FORCE, AGT BY EXTENSOMETER
Elongation at maximum force by
extensometer method
• extensometer used shall have a gauge
length (Le) of at least 100 mm
• extension at maximum force (ΔLm)
Agt 
By Manual Method
• measuring the plastic elongation at
maximum force, from which the
percentage total elongation shall be
calculated.
• equidistant marks shall be made on the
free length of the test specimens.
• The distance between the marks shall be
20 mm, 10 mm or 5 mm
Lm
.100
Le
By Manual Method
• The measurement of the final gauge length
after fracture shall be made on the longest
broken part of the test specimens and
shall be accurate to within 0.5 mm
Agt  Ag 
Rm
2000
• Rm is the tensile strength of the test
specimen; & Ag is the percentage plastic
elongation at maximum force
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2012/12/20
Choice of different methods
• The measurement of Ag shall be made on a
gauge length of 100 mm, as close as possible
to the fracture but at a distance, r2, of at least
50 mm or 2d (whichever is the greater) away
from the fracture.
• This measurement shall be considered as
invalid if the distance, r1, between the grips
and the gauge length is less than 20 mm or d
(whichever is the greater).
• The extensometer method may be
replaced by the manual method.
• In case of dispute, the manual method
shall be applied.
Howto
tomeasure
measure Agt
How
Agt? ?
What
is ductility
??
How
to define
ductility
ISO 10606 : Steel for the reinforcement of concrete –
Determination of percentage total elongation at
maximum force
Stress, s
1
Elongation at break
( A5)
2
3
Ductility ratio,
fu
(
fu
)
fy
1
brittle
fy
Use extensometer
s
Rm
ductile
0.1%Rm min.
X
Failure
Elongation at max. load
( Agt )
Agt
Elastic e
Agt
A5
Strain, e
2
e
Measure after fracture
L
 L  L0 Rm 
Agt  

 100
E
 L0
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2012/12/20
Table 8 – Absolute minimum and
maximum values of tensile properties
Minimum value
Performance
characteristic
Mechanical - Rebend
• (a) the test specimen shall be bent through an
angle of 90º round a mandrel with diameter not
exceeding specified Table 11
Maximum value
250
500B
500C
250
500B
500C
Re, MPa
243
485
485
N/A
650
650
Rm/Re
1.13
1.06
1.13
N/A
N/A
1.38
Agt, %
4.0
4.0
6.0
N/A
N/A
N/A
Mechanical - Rebend
• (c) the test specimen shall be bent back
towards its original shape (partially
re-straightened) by a steadily applied force
through at least 20º on the same bending
machine as used above.
• (b) ageing shall be performed artificially by
placing the test specimen at a temperature of
100ºC, maintaining at this temperature 10ºC for
a period of 1 hour 0 to +15 min. and then
cooling in still air to room temperature; and
Table 11 – Rebend test mandrel
Grade
Nominal diameter,
Maximum
d (mm)
mandrel diameter
250
All sizes
2d
500B &
500C
16
>16
4d
7d
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2012/12/20
Table 4 – Chemical composition
(maximum % by mass)
Chemical Analysis
― The chemical composition (product
analysis) shall be determined by
spectrometric methods or an appropriate
method specified in the International
Standards listed in the bibliography of
― BS EN ISO 15630-1:2010.
Grade
250
Cast
analysis 500B
500C
250
Product
analysis 500B
500C
Table 2: Chemical composition
(maximum % by mass)
Cast
analysis
Product
analysis
Carbon
Sulphur
Phosphorus
Nitrogen
Copper
Carbon
Equivalent
0.22
0.05
0.05
0.012
0.80
0.42
0.22
0.05
0.05
0.012
0.80
0.50
0.24
0.055
0.055
0.014
0.85
0.44
0.24
0.055
0.055
0.014
0.85
0.52
Carbon Equivalent Value
Grade
Carbon
(碳)
Sulphur
(硫)
Phosphorus
(磷)
Nitrogen
(氮)
Copper
(銅)
Carbon
Equivalent
•
250
0.22
0.05
0.05
0.012
0.80
0.42
500B
&
500C
0.22
0.05
0.05
0.012
0.80
0.50
250
0.24
0.055
0.055
0.014
0.85
0.44
500B
&
500C
0.24
0.055
0.055
0.014
0.85
0.52
•
•
•
•
•
•
•
Mn Cr  Mo  V Ni  Cu


6
5
15
C is the percentage carbon (碳) content;
Mn is the percentage manganese(錳)content;
Cr is the percentage chromium (鉻)content;
Mo is the percentage molybdenum (鉬)content;
V is the percentage vanadium (釩) content;
Ni is the percentage nickel (鎳) content; and
Cu is the percentage copper (銅)content.
Ceq  C 
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2012/12/20
Tensile test – force machine
Class of force machine
at least Class 1
• The forcemeasuring system
of the testing
machine shall be
calibrated to at
least Class 1 in
accordance with
• ISO 7500-1:2004.
Tensile test - Extensometer
Classification of extensometer
at least Class 2
• The extensometer
shall be calibrated to
at least Class 1 in
accordance with ISO
9513:1999 for the
determination of Rp0.2;
for the determination
of Agt, a Class 2
extensometer can be
used.
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2012/12/20
Test procedure
• The tensile test
shall be carried out
in accordance with
• BS EN
• ISO 6892-1:2009
Bond strength & surface geometry
• “Bond property” requirements of ribbed
steel reinforcing bars shall be based on
surface geometry as determined in Cl.
6.1 and 6.7.2 or bond stresses as
determined by beam test in Cl. 6.1 and
6.7.3.
• “Bond property” requirements based on
surface geometry are preferred.
Surface Geometry
• Ribbed steel reinforcing bars are characterised
by the dimensions, number and configuration
of transverse and longitudinal ribs.
• They shall have two or more rows of transverse
ribs uniformly distributed around the
perimeter.
• Within each row the ribs shall be uniformly
spaced.
• Longitudinal ribs can be present or not.
Steel bar from H K
Shiu Wing Steel Ltd
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2012/12/20
Steel bars
from China
Rib height, spacing & angle
The values for the spacing, height and rib inclination
angle of transverse ribs shall be within the ranges
Rib height, h
Rib spacing, c
Transverse rib
inclination
angle, 
0.03d to 0.15d
0.4d to 1.2d
35º to 75º
Steel bars
from Taiwan
Table 7: Characteristic
relative rib area
The characteristic relative rib area shall meet the requirements
Nominal bar size, d
(mm)
Relative rib area, fR
d6
0.035
6 < d  12
0.040
d > 12
0.056
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2012/12/20
Recommended formula for
calculating of relative rib area
The relative rib area, fR, for ribbed steel
reinforcing bars shall be calculated by using
the Simpson’s rule formula
f R  (2a1 4  am  2a3 4 )  (d   ei ) 
1
6dc
Definitions of “∑ei ”
• ∑ei is the part of the circumference without
ribs determined as the sum of the average
gap e between each pair of two adjacent
ribs. “e” shall be determined from at least
3 measurements;
Definition of “a”
am
is the height of transverse ribs at
the mid-point determined as the mean of
at least 3 measurements in this position
per row on different transverse ribs;
a1/4
is the height of transverse ribs at
the quarter-point determined as the mean
of at least 3 measurements in this position
per row on different transverse ribs;
a3/4
is the height of transverse ribs at
the three-quarters point determined as the
mean of at least 3 measurements in this
position per row on different transverse ribs;
Definition of “C”
“C” is the spacing of the transverse ribs
determined from the measured length divided by
the number of the rib gaps included in it.
The measured length shall be at least 10 rib gaps
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2012/12/20
Transverse ribs
• The projection of the transverse ribs shall extend
over at least 75% of the circumference of the
steel reinforcing bar, which shall be calculated
from the nominal diameter.
• The transverse rib flank inclination angle  shall
be greater than or equal to 45º, and the
transition from the rib to the core shall be
radiused.
Longitudinal ribs
• Where longitudinal ribs are present, their
height shall not exceed 0.10d, where d is the
nominal diameter of the steel reinforcing bar.
Retests (1)
Retests (2)
• For each test specimen and failing to meet
the requirements for the mass per metre,
chemical composition (product analysis),
tensile properties, bend performance or
bond property, two additional test
specimens may be taken from different
steel reinforcing bars of the same batch
and be subjected to the test or tests which
the original specimen failed
• If all of the additional test specimens pass the
retests, the batch from which they have been
taken shall be deemed to comply with this CS2
• For properties other than chemical composition,
the batch shall be deemed not to comply with this
CS2 if any of mass, tensile, surface geometry
fails.
• For chemical composition (product analysis), the
batch shall be deemed not to comply with this
CS2 if anyone of the 10 elements fails.
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2012/12/20
Product Certification
•
•
•
•
Steel rebar production plant
Stockist of rebars
Off site cut and bend
Steel Coupler
CS2:2013
• “Stage 1”
• Updating the technical specification and
quality assurance system for steel
reinforcing bars to align with BS4449:
2005 (Non-product certified steel rebars)
• “Stage 2”
• Requirement for Product certified steel
rebars
17
2012/12/20
Facade Group
PRODUCT CONFORMITY CERTIFICATION
SCHEME
FOR
ALUMINIUM WINDOWS
(PCCS - AW)
PARTS ONE & TWO
Administrative Regulations
Technical Regulations
Issue 1
October 2011
HONG KONG INSTITUTE OF STEEL CONSTRUCTION
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2012/12/20
PRODUCT CONFORMITY CERTIFICATION SCHEME
FOR
MESH REINFORCEMENTS
(PCCS – MR)
PARTS ONE & TWO
Coupler for
Steel Reinforcing Bar
Administrative Regulations
Technical Regulations
Issue 1
15 November 2012
Draft v1
Coupler for CS2:2013
Steel Rebar to meet
Static & Seismic Requirements
HONG KONG CONCRETE INSTITUTE
BD Reinforced Concrete Code
Coupler for CS2:2013 Steel Rebar to meet
AC133 Seismic Requirements
19
2012/12/20
QR Code Technology
on Ductility Coupler
QR Code Technology
on Ductility Coupler
• Cloud Certification
• Features:
– Low Cost, Durable
– Instant Response
– High Data Capacity Storing
Product Data, Image and
Audio Data
– Reliable with Data Encryption
– Flexible Label Size
Corrosion of Steel Rebar
Stainless Steel Rebar
to resist corrosion
20
2012/12/20
Austenitic and Austenitic-Ferritic
Duplex stainless steels
BS 6744:2001
Steel grades
AISI
304 *
316 *
329
---
(austenitic)
(austenitic)
(duplex)
(superaustenic)
1.4436
1.4462
1.4529
EN 10088-1 1.4301
Cogne
304HT
316HT
329HT
354/1
C
<=0.07
<=0.05
<=0.03
<=0.02
Mn
<=2.0
<=2.0
<=2.0
<=1.0
P
<=0.045
<=0.045
<=0.035
S
<=0.03
<=0.015
Si
<=1.0
Ni
Cr
Grade
BS EN 10088-1 :2005
0,2% proof
Stress ratio
Elongation at
Total elongation at
Rm/Rp0,2
fracture
max force
(min)
A5 (min.)%
Agt (min)%
200
1,10
22
5
500
500
1,10
14
5
650
650
1,10
14
5
GRADE strength
Rp0,2 MPa
200 *
<=0.030
<=0.015
<=0.010
<=1.0
<=1.0
<=0.5
8.0 - 10.5
10.0 - 13.0
4.5 - 6.5
24 - 26
17 - 19.5
16.5 - 18.5
21 - 23
19 - 21
Mo
-
2.5 - 3.0
2.5 - 3.5
6-7
N
<=0.11
<=0.11
0.1 - 0.2
0.15 - 0.25 + Cu
Rm is the ultimate tensile strenght
Conclusion
• CS2:2013 Stage 1
• Purchaser testing: Mechanical, Chemical and Bond
Property
• CS2:2014/2015 (?????) Stage 2
• Product Certification of Steel Mill, Stockist, Off-site Cut
& Bend and Steel Coupler
• Electronic labelling (QR Code or RFID)
• Stainless steel reinforcing bars
• Off site fabrication of steel rebars for beam, columns
and slabs
Thank you
21