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GB/T 21839-2008 PDF in English


GB/T 21839-2008 (GB/T21839-2008, GBT 21839-2008, GBT21839-2008)
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GB/T 21839-2008: PDF in English (GBT 21839-2008)

GB/T 21839-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.15; 77.040.01
H 20
Steel for prestressed concrete - Test methods
(ISO 15630-3.2002, Steel for the reinforcement and prestressing of
concrete - Test methods - Part 3. Prestressing steel, MOD)
ISSUED ON. MAY 13, 2008
IMPLEMENTED ON. NOVEMBER 1, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 4 
1 Scope ... 5 
2 Normative references ... 5 
3 Symbol description ... 6 
4 General provisions concerning test pieces ... 7 
5 Tensile test ... 8 
6 Bend test ... 9 
7 Reverse bend test ... 11 
8 Torsion test ... 11 
9 Wrapping test ... 12 
10 Isothermal stress relaxation test ... 12 
11 Axial load fatigue test ... 17 
12 Stress corrosion test in a solution of thiocyanate ... 19 
13 Deflected tensile test ... 22 
14 Chemical analysis ... 26 
15 Measurement of the geometrical dimensions ... 27 
16 Determination of the relative rib area (fR) ... 29 
17 Determination of deviation from nominal mass per meter ... 31 
18 Test report ... 32 
Annex A (Informative) Tensile test method of the steel strand for prestressed
concrete ... 33 
Annex B (Informative) Contrast table for the clauses of this Standard and ISO
15630-3.2002 ... 36 
Foreword
This Standard uses ISO 15630-3.2002 Steel for the reinforcement and
prestressing of concrete - Test methods - Part 3. Prestressing steel (EN) after
modification.
This Standard was redrafted in accordance with ISO 15630-3.2002.
Due to the provisions of relevant national specifications and actual industrial
requirements, this Standard has made modifications when using the
international standard. These technical differences are identified by vertical
single lines in the margins of the terms to which they relate. For the contrast for
the sections of this Standard and corresponding international standard ISO
15630-3.2002, SEE Annex B.
In order to facilitate the use of the manufacturing plants and users in our
national prestressed industry, compared with corresponding international
standard, this Standard has mainly made the following technical modifications.
— ADD Chapter 8 “Torsion test”;
— ADD Chapter 9 “Wrapping test”;
— ADD Annex A “Test method of multi-wire steel strands for prestressed
concrete”.
Annexes A and B of this Standard are informative annexes.
This Standard was proposed by the China Iron and Steel Industry Association.
This Standard shall be under the jurisdiction of the National Technical
Committee for Standardization of Steels.
Drafting organizations of this Standard. China National Construction Steel
Quality Supervision and Test Centre, Tianjin Golik-The First PC Steel Strand
Co., Ltd, Shanghai Second Steel Plant Co., Ltd of Baosteel Group, and China
Metallurgical Information and Standardization Institute.
Main drafters of this Standard. Zhu Jianguo, Zhang Ying, Cui Lixin, Mao Aiju,
Liu Lijun, Li Wenjia, Zhang Enwei, Zhou Daiyi, Wang Lingjun and Dai Shifeng.
Steel for prestressed concrete - Test methods
1 Scope
This Standard specifies the test methods for tensile, bend, reverse bend,
torsion, wrapping, isothermal relaxation, fatigue, stress corrosion, deflected
tensile, chemical analysis, measurement of the geometrical dimensions, and
determination of the relative rib area of the steel for prestressed concrete.
This Standard is applicable to the determination of the properties with regard
to the prestressed steel wires, bars, strands, etc.
2 Normative references
The provisions in the following documents become the provisions of this
Standard through reference in this Standard. For dated references, the
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, parties who reach an agreement based on this
Standard are encouraged to study if the latest editions of these documents are
applicable. For undated references, the latest editions apply to this Standard.
GB/T 228 Metallic materials - Tensile testing at ambient temperature (GB/T
228-2002, eqv ISO 6892.1998)
GB/T 230.1 Metallic Rockwell hardness test - Part 1. Test method (scales A,
B, C, D, E, F, G, H, K, N, T) (GB/T 230.1-2004, ISO 6508-1.1999, MOD)
GB/T 232 Metallic materials - Bend test (GB/T 232-1999, eqv ISO 7438.1985)
GB/T 238 Metallic materials - Wire - Reverse bend test (GB/T 238-2002, ISO
7801.1984, IDT)
GB/T 239 Metallic materials - Wire - Torsion test (GB/T 239-1999, eqv ISO
7800.1984)
GB/T 2976 Metallic materials - Wire - Wrapping test (GB/T 2976-2004, ISO
7802.1983, IDT)
GB/T 3505 Geometrical product specifications (GPS) - Surface texture.
Profile method - Terms, definitions and surface texture parameters (GB/T
3505-2000, eqv ISO 4287.1997)
GB/T 12160-2002 Calibration of extensometers used in uniaxial testing
(GB/T 12160-2002, ISO 9513.1999, IDT)
GB/T 16825.1 Verification of static uniaxial testing machines - Part 1.
Tension/compression testing machines - Verification and calibration of the
force-measuring system (GB/T 16825.1-2002, ISO 7500-1.1999, IDT)
3 Symbol description
The symbols used in this Standard are shown in Table 1.
Table 1 Symbols
Symbol Unit Description Reference
hm mm Rib height at the mid-point 15.3, 16.2
hmax mm Maximum depth of indentation / rib height at the highest point 15.3
hs,i mm Average height of the rib per unit length ᇞl 16.2
h1/4 mm Rib height at the quarter-point 15.3, 16.2
h3/4 mm Rib height at the three-quarters point 15.3, 16.2
Agt % Percentage total elongation at maximum force 5
A % Percentage elongation after fracture 5.3.1
At % Percentage total elongation at break 5.3.1
c mm Rib or indentation spacing 15.3
C mm Groove width of the mandrel used for the deflected tensile test 13.3.4
d mm Nominal diameter of the prestressed steel bar, wire or strand 11.2, 11.4.6, 12.3.4
da mm Nominal diameter of the mandrel used for the deflected tensile test 13.3.4
db mm Diameter with 2 gauge cylinders in the groove of the mandrel used for the deflected tensile test 13.3.4
de mm Diameter of the gauge cylinder used for the deflected tensile test 13.3.4
di mm Inner diameter of the groove of the mandrel used for the deflected tensile test 13.3.4
D % Average coefficient of reduction of the maximum force in the deflected tensile test 13.2, 13.4
Dc mm Inner diameter of the cell in the stress corrosion test 12.3.4
Di % Individual percentage of reduction of the maximum force in the deflected tensile test 13.4
e mm Average gap between two adjacent rib or indentation rows 15.3.1.4, 15.3.2.4
E N/mm2 Modulus of elasticity 5.3
f Hz Frequency of load cycles in the axial load fatigue test 11.1, 11.4.2
fR 1 Relative rib area 16
Fa,i N Individual breaking force in the deflected tensile test 13.4
Fm N Maximum force 5.3
Fm,m N Mean value of the maximum force 10.2, 12.2, 13.2
Fp0.1 N 0.1% proof force 5.3
distance between the cross-heads and this value is added to the percentage obtained by
extensometer, which is the percentage total elongation at break At.
For steel wires and bars, it is also permissible to determine Agt by drawing
equidistant marks on the free length of the test piece. USE the determined A to
replace Agt. The distance between the marks shall be 20mm, 10mm or 5mm,
depending on the wire or bar diameter.
NOTE 2. It is preferable to preload the test piece, e.g. to about 10% of the expected maximum force before
placing the extensometer.
If Agt is not completely determined by using an extensometer, this shall be
indicated in the test report.
Tensile properties, Fp0.1, Fp0.2 and Fm, are recorded in force units.
When the rupture occurs within a distance of 3mm from the grips, the test shall,
in principle, be considered as invalid, and shall be permissible to carry out a
retest. However, it shall be permitted to take into account the test results if all
values are greater than or equal to the relevant specified values.
5.3.2 Determination of the modulus of elasticity
The modulus of elasticity (E) shall be determined from the slope of the linear
portion of the force-extension diagram i...
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.