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GB/T 13788-2017 English PDF (GBT13788-2017)

GB/T 13788-2017 English PDF (GBT13788-2017)

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GB/T 13788-2017: Cold rolled ribbed steel bars

This Standard specifies the terms and definitions, classification, designation, size, shape, weight, allowable deviation, technical requirements, test methods, inspection rules, packaging, marking, and quality certificate of cold rolled ribbed steel bars.
GB/T 13788-2017
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.60
H 44
Replacing GB/T 13788-2008
Cold rolled ribbed steel bars
ISSUED ON. JULY 12, 2017
IMPLEMENTED ON. APRIL 1, 2018
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the PRC;
Standardization Administration of the PRC.
3. No action is required - Full-copy of this standard will be automatically and immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope .. 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Classification and designations ... 6
5 Size, shape, weight, and allowable deviation .. 6
6 Technical requirements ... 13
7 Test methods ... 15
8 Inspection rules .. 16
9 Packaging, marking, and quality certificate ... 17
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009. This Standard replaces GB/T 13788-2008 ?€?Cold rolled ribbed steel wires and bars?€?. As compared with GB/T 13788-2008, the main technical changes of this Standard are as follows.
- RIVISE relevant provisions on classification and codes;
- ADD the designations of high-elongation cold rolled ribbed steel bars. CRB600H, CRB680H, and CRB800H;
- ADD the shape, size and mark diagram of four-sided ribbed steel bars; - RIVISE relevant provisions on the designation and chemical composition; - ADD the mechanical property requirement for high-elongation cold rolled ribbed steel bars CRB600H, CRB680H, and CRB800H;
- RIVISE relevant provisions on percentage elongation after fracture,
percentage total elongation at maximum force (Agt) and tensile-to-yielding ratio;
- RIVISE relevant provisions on test methods;
- DELETE Appendix A ?€?Determination methods of steel bars at percentage
total elongation at maximum force?€?;
- DELETE Appendix B ?€?Reference designations and chemical composition
of wire rods for cold rolled ribbed steel bars?€?.
This Standard was proposed by China Iron and Steel Association.
This Standard shall be under the jurisdiction of China National Standardization Technology Committee (SAC/TC 183).
Drafting organizations of this Standard. Central Research Institute of Building and Construction Co., Ltd., Anyang Heli Techtronic Co., Ltd., Anhui BRC and Ma Steel Weldmesh Co., Ltd., Silvery Dragon Prestressed Materials Co., Ltd. Tianjin, and China Metallurgical Information and Standardization Institute. Main drafters of this Standard. Yue Qingrui, Feng Chao, Tao Ran, Zhai Wen, Guo Sihong, Ai Tieling, Li Yajie, Zhang Pingyuan, Xie Zhian, Liu Baoshi, Wang Xianhua, Du Ruiqing, Zhang Ying, Wang Yujie.
Cold rolled ribbed steel bars
1 Scope
This Standard specifies the terms and definitions, classification, designation, size, shape, weight, allowable deviation, technical requirements, test methods, inspection rules, packaging, marking, and quality certificate of cold rolled ribbed steel bars.
This Standard is applicable to cold rolled ribbed steel bars for prestressed concrete and ordinary reinforced concrete, and cold rolled ribbed steel bars (known as steel bars for short hereinafter) for manufacturing welded mesh. 2 Normative references
The following documents are essential to the application of this document. For the dated references, only the versions with the dates indicated are applicable to this document. For the undated references, the latest version (including all the amendments) are applicable to this document.
GB/T 2101 General requirement of acceptance packaging marking and
certification for section steel
GB/T 2103 General requirements for acceptance, packing, marking and
quality certification of steel wire
GB/T 17505 Steel and steel products General technical delivery
requirements
GB/T 21839 Steel for prestressed concrete - Test methods
GB/T 28899 Wire rods for cold rolled ribbed steel bars
GB/T 28900 Test methods of steel for reinforcement of concrete
YB/T 081 Rule for Rounding Off of Numerical Values and Judgement of
Testing Values for Technical Standards of Metallurgy
3 Terms and definitions
The following terms and definitions are applicable to this document.
The range of nominal diameter of CRB550, CRB600H, and CRB680H steel
bars is 4 mm~12 mm. The nominal diameter of CRB650, CRB800, and
CRB800H is 4 mm, 5 mm, and 6 mm.
5.2 Shape
5.2.1 The transverse ribs on the surface of steel bars shall conform to the provisions of 5.2.1.1~5.2.1.6.
5.2.1.1 The transverse ribs of two-sided and three-sided ribbed steel bars shall be crescent. The longitudinal section of transverse ribs of four-sided ribbed steel bars shall be crescent and shall not intersect with the transverse ribs. 5.2.1.2 Transverse ribs shall be uniformly distributed along the circumferential ring of the cross section of steel bars. The inclination of one rib of two-sided ribbed steel bars shall be reversed with the other rib. The inclination of one rib of three-sided ribbed steel bars shall be reversed with the other two ribs. The inclination of the two adjacent transverse ribs of four-sided ribbed steel ribs shall be opposite to that of the other two transverse ribs.
5.2.1.3 The included angle ?? between the center line of the transverse rib and the longitudinal axis of the steel bar of two-sided and three-sided ribbed steel bars is 40??~60??. The included angle between the axis of the transverse rib and the axis of the steel bar of four-sided ribbed steel bars shall be 40??~70??; the angle between the two rows of ribs can be 35??~75??.
5.2.1.4 The bevel angle ?? between the two sides of the transverse rib and the surface of the steel bar of two-sided and three-sided ribbed steel bars shall not be less than 45??. The bevel angle ?? between the two sides of the transverse rib and the surface of the steel bar of four-sided ribbed steel bars shall not be less than 40??. The transverse rib shall intersect the surface of the steel bar in an arc. 5.2.1.5 The sum of rib spacing of two-sided and three-sided ribbed steel bars shall not be greater than 20% of the nominal circumference (???fi ??? 0.2?€d). The sum of rib spacing of four-sided ribbed steel bars shall not be greater than 25% of the nominal circumference (???fi ??? 0.25?€d).
5.2.1.6 The specific rib area fr shall be determined by the equation (1). Where.
K=2, 3, or 4 (two-sided ribs, three-sided ribs, or four-sided ribs);
demand parties, it can also be delivered according to a specified length. When the steel bar is delivered according to a specified length, the length and allowable deviation shall be determined through consultation between the supply-demand parties.
5.5 Bending
The bending per meter of straight steel bars shall not be more than 4 mm. The total bending shall not be greater than 0.4% of the total length of the steel bar. 5.6 Weight
5.6.1 The weight of a coiled steel bar shall not be less than 100 kg. Each coil shall be made up of a steel bar. When CRB650, CRB680H, CRB800, CRB800H
are used as steel bars for prestressed concrete, there shall be no welded joints. 5.6.2 The straight steel bar, according to the same designation, the same specification, and the same length, shall be delivered in bundles. The weight of the bundle shall be determined by consultation between the supply-demand parties.
6 Technical requirements
6.1 Raw material
The raw material for manufacturing steel bars shall be in accordance with the provisions of GB/T 28899. The wire rods produced according to other standards can also be used.
6.2 Delivery state
The steel bar is delivered in cold working state. It is allowed that low temperature tempering is implemented after cold rolling.
6.3 Mechanical and processing properties
6.3.1 The mechanical and processing properties of steel bars shall conform to the provisions of Table 3. When carrying out a bending test, there shall be no crack on the surface of the bent part. The bending radius of repeated bending test shall conform to the provisions of Table 4.
7.3.2 The sample may be mechanically straightened. But there shall not be any heat treatment and other cold working.
7.3.3 The initial test force applied to the sample is that, 70% of the nominal tensile strength of the sample multiplies by the nominal cross-sectional area of the sample.
7.3.4 The loading speed is 200 MPa/min??50 MPa/min. The initial load shall be completed in 3 min~5 min. After holding the load for 2 min, the relaxation value shall be recorded.
7.3.5 The sample length is not less than 60 times the nominal diameter. 7.3.6 The relaxation rate of 1000 h is allowed to be calculated from the test data of at least 120 h.
7.4 Size measurement
7.4.1 The height of the transverse rib is the average value of the height of each column of transverse ribs of the same section. MEASURE the average distance to determine the distance between transverse ribs, that is, MEASURE the center distance between the 1st and 11th transverse ribs in the same column and DIVIDE it by 10, and OBTAIN the average value of distance between
transverse ribs.
7.4.2 The size measurement shall be accurate to 0.02 mm.
7.5 Measurement of weight deviation
When measuring the weight deviation of steel bar, the sample length shall not be less than 500 mm. Length measurement shall be accurate to 1 mm. Weight measurement shall be accurate to 1 g. The weight deviation of steel bar (%) shall be calculated according to the equation (3).
7.6 Rounding off for values
The rounding off and determination for values of the inspection results shall conform to the provisions of YB/T 081.
8 Inspection rules
8.1 Inspection and acceptance
Weight deviation
Actual weight of sample - (length of sample x theoretical weight)
Length of sample x theoretical weight
The inspection and acceptance of steel bar shall be carried out by the Quality Supervision Department of the supply party. The demand party shall have the right to inspect.
8.2 Batching rules
The steel bars shall be inspected and accepted in batches. Each batch shall be made up of the steel bars of the same designation, same shape, same
specification, same production process, and same delivery state. Each batch shall not be more than 60 t.
8.3 Sampling quantity
The sampling quantity of the inspection of steel bar shall be in accordance with the provisions of Table 5.
8.4 Rules for re-inspection and determination
The rules for re-inspection and determination of steel bar shall conform to the provisions of GB/T 17505.
9 Packaging, marking, and quality certificate
9.1 Each coil (bundle) of steel bars shall be tied up evenly for not less than 3 lines. The end socket shall be bent into the coil.
9.2 The steel bar shall be rolled with obvious designation-marks. The distance between marks is twice that between transverse ribs; one transverse rib within the distance between marks shall be deleted, as shown in Figure 4. It shall add a short transverse rib within the third distance between marks to high- elongation cold rolled ribbed steel bars, as shown in Figure 5. Steel bars can also be rolled with the factory name or logo.
9.3 There shall be not less than two signs hanging on each coil (bundle) of steel bars, which indicate the manufacturer, date of production, designation-number and specification of the steel bar.
9.4 The packaging, marking, and quality certificate of steel bars, except as stated above, shall comply with the relevant provisions of GB/T 2101 or GB/T 2103.

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