Codeofchina.com is in charge of this English Translation. In case of any doubt about the English Translation, the Chinese original shall be considered authoritative.
This standard is developed 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. The following technical changes have been made with respect to GB/T 13788-2008:
——Requirements for classification and symbols are modified.
——Designations CRB600H, CRB680H and CRB800H are added for high-elongation cold rolled ribbed steel bars;
——Appearance, dimensions and marking pattern of four-side rib steel bars are added;
——Requirements for designation and chemical composition are modified;
——Mechanical properties requirements of high elongation cold rolled ribbed steel bars CRB600H, CRB680H and CRB800H are added;
——Requirements for elongation percentage at fracture, total extension percentage Agt at maximum force and yield ratio are modified;
——Requirements for test methods are modified;
——Annex A Determination method of steel bar on total elongation at the maximum force is deleted.
——Annex B Referential designation and chemical composition of wire rods used for cold rolled ribbed steel bars is deleted.
This standard was proposed by the China Iron and Steel Industry Association
This standard is under the jurisdiction of SAC/TC 183 National Technical Committee on Steel of Standardization Administration of China.
The previous editions of this standard are as follows:
GB 13788-1992, GB 13788-2000, GB/T 13788-2008.
Cold rolled ribbed steel bars
1 Scope
This standard specifies the terms and definitions, classification, designation, dimension, appearance, weight and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and certification of cold-rolled ribbed steel bars.
This standard is applicable to cold-rolled ribbed steel bars used for prestressed concrete and ordinary reinforced concrete, it is also applicable to the cold-rolled ribbed steel bars used for manufacturing welded mesh (hereafter referred to as simply steel bars).
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) is applicable to this document.
GB/T 2101 General requirement of acceptance packaging, marking and certification for section steel
GB/T 2103 General requirements for checking, packing, marking and certification of steel wire
GB/T 17505 Steel and steel products - General technical delivery requirements
GB/T 21839 Test methods of steel for prestressing concrete
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 numberical values and judgement of testing values for technical standards of metallurgy
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
cold rolled ribbed steel bars
steel bars with ribs evenly distributed along the length on the surface of hot-rolled wire rods after cold rolling
3.2
nominal diameter
nominal diameter of plain round bar equivalent to cross sectional area
3.3
specific projected rib area
ratio of the product of the projected area of the rib on a plane vertical to axial line of steel bar to the nominal perimeter and the spacing between ribs
3.4
rib spacing
chord length of the discontinuity of the ribs on the circumferential surface of the bar projected perpendicular to the axis of the bar
4 Classification, designation
4.1 Classification and symbols
Cold-rolled ribbed steel bars are classified into two categories by ductility:
Cold-rolled ribbed bars CRB
High elongation cold-rolled ribbed bars
CRB + tensile strength characteristic value + H
C, R, B, H are the first letter of the four English words Cold rolled, Ribbed, Bar and High elongation.
4.2 Designation
Steel bars have 6 designations, i.e. CRB550, CRB650, CRB800, CRB600H, CRB680H and CRB800H. CRB550 and CRB600H are for ordinary reinforced concrete, CRB650, CRB800 and CRB800H are for prestressed concrete, CRB680H can be used for either ordinary reinforced concrete or prestressed concrete.
5 Dimension, appearance, weight and allowance deviation
5.1 Nominal diameter scope
The nominal diameter scope of CRB550, CRB600H and CRB680H is 4 mm to 12 mm, and that of CRB650, CRB800, CRB800H is 4 mm, 5 mm, 6 mm.
5.2 Appearance
5.2.1 Ribs on the surface of steel bar shall meet the requirements of 5.2.1.1 to 5.2.1.6
5.2.1.1 Dihedral rib and trihedral rib are in the shape of crescent, while the longitudinal section of tetrahedral rib shall be crescent and shall not intersect with the ribs.
5.2.1.2 The ribs shall be evenly distributed along the cross section periphery on steel bar. The slope of one rib of the dihedral rib shall be opposite to the other side, while one rib of the trihedral rib shall be opposite to the other two sides. The slope of two adjacent ribs of the tetrahedral rib shall be opposite to the other two sides.
5.2.1.3 The included angle β between the rib centerline and steel bar longitudinal axis of dihedral rib and trihedral rib shall be 40°~ 60°. The included angle between the rib axis of dihedral rib and steel bar axis shall be 40° to 70°, the angle between two rows of ribs may be 35° to 75°
5.2.1.4 The slope α between the two sides of dihedral rib and trihedral rib and the surface of steel bar, shall not be less than 45°, while that of tetrahedral rib shall not be less than 40°. The rib and surface of steel bar shall intersect in the shape of curve.
5.2.1.5 The sum of rib spacing between dihedral rib and trihedral rib shall not be greater than of the nominal perimeter, and the sum of rib spacing of tetrahedral rib shall not be greater than of the nominal perimeter.
5.2.1.6 The relative rib area fr shall be determined according to Formula (1):
(1)
Where,
K=2, 3 or 4 (dihedral rib, trihedral rib or tetrahedral rib)
FR——longitudinal cross section area of one rib, in square millimeter (mm2);
β——included angle between rib and steel bar axis, in degree (°);
d——nominal diameter of steel bar, in millimeters (mm);
l——rib spacing, in millimeters(mm).
Given the geometric parameter of steel bar, the relative rib area may also be calculated by approximate formula below:
(2)
Where;
——sum of rib spacing on each steel bar periphery, in millimeters (mm);
h—— rib midpoint height, in millimeters (mm);
h1/4——1/4 height of the rib, in millimeters (mm).
5.2.2 The shape of dihedral ribbed steel bar shall comply with the rules in Figure 1 and 5.2.1.
Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Classification, designation
5 Dimension, appearance, weight and allowance deviation
6 Technical requirements
7 Test method
8 Inspection rules
Codeofchina.com is in charge of this English Translation. In case of any doubt about the English Translation, the Chinese original shall be considered authoritative.
This standard is developed 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. The following technical changes have been made with respect to GB/T 13788-2008:
——Requirements for classification and symbols are modified.
——Designations CRB600H, CRB680H and CRB800H are added for high-elongation cold rolled ribbed steel bars;
——Appearance, dimensions and marking pattern of four-side rib steel bars are added;
——Requirements for designation and chemical composition are modified;
——Mechanical properties requirements of high elongation cold rolled ribbed steel bars CRB600H, CRB680H and CRB800H are added;
——Requirements for elongation percentage at fracture, total extension percentage Agt at maximum force and yield ratio are modified;
——Requirements for test methods are modified;
——Annex A Determination method of steel bar on total elongation at the maximum force is deleted.
——Annex B Referential designation and chemical composition of wire rods used for cold rolled ribbed steel bars is deleted.
This standard was proposed by the China Iron and Steel Industry Association
This standard is under the jurisdiction of SAC/TC 183 National Technical Committee on Steel of Standardization Administration of China.
The previous editions of this standard are as follows:
GB 13788-1992, GB 13788-2000, GB/T 13788-2008.
Cold rolled ribbed steel bars
1 Scope
This standard specifies the terms and definitions, classification, designation, dimension, appearance, weight and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and certification of cold-rolled ribbed steel bars.
This standard is applicable to cold-rolled ribbed steel bars used for prestressed concrete and ordinary reinforced concrete, it is also applicable to the cold-rolled ribbed steel bars used for manufacturing welded mesh (hereafter referred to as simply steel bars).
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) is applicable to this document.
GB/T 2101 General requirement of acceptance packaging, marking and certification for section steel
GB/T 2103 General requirements for checking, packing, marking and certification of steel wire
GB/T 17505 Steel and steel products - General technical delivery requirements
GB/T 21839 Test methods of steel for prestressing concrete
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 numberical values and judgement of testing values for technical standards of metallurgy
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
cold rolled ribbed steel bars
steel bars with ribs evenly distributed along the length on the surface of hot-rolled wire rods after cold rolling
3.2
nominal diameter
nominal diameter of plain round bar equivalent to cross sectional area
3.3
specific projected rib area
ratio of the product of the projected area of the rib on a plane vertical to axial line of steel bar to the nominal perimeter and the spacing between ribs
3.4
rib spacing
chord length of the discontinuity of the ribs on the circumferential surface of the bar projected perpendicular to the axis of the bar
4 Classification, designation
4.1 Classification and symbols
Cold-rolled ribbed steel bars are classified into two categories by ductility:
Cold-rolled ribbed bars CRB
High elongation cold-rolled ribbed bars
CRB + tensile strength characteristic value + H
C, R, B, H are the first letter of the four English words Cold rolled, Ribbed, Bar and High elongation.
4.2 Designation
Steel bars have 6 designations, i.e. CRB550, CRB650, CRB800, CRB600H, CRB680H and CRB800H. CRB550 and CRB600H are for ordinary reinforced concrete, CRB650, CRB800 and CRB800H are for prestressed concrete, CRB680H can be used for either ordinary reinforced concrete or prestressed concrete.
5 Dimension, appearance, weight and allowance deviation
5.1 Nominal diameter scope
The nominal diameter scope of CRB550, CRB600H and CRB680H is 4 mm to 12 mm, and that of CRB650, CRB800, CRB800H is 4 mm, 5 mm, 6 mm.
5.2 Appearance
5.2.1 Ribs on the surface of steel bar shall meet the requirements of 5.2.1.1 to 5.2.1.6
5.2.1.1 Dihedral rib and trihedral rib are in the shape of crescent, while the longitudinal section of tetrahedral rib shall be crescent and shall not intersect with the ribs.
5.2.1.2 The ribs shall be evenly distributed along the cross section periphery on steel bar. The slope of one rib of the dihedral rib shall be opposite to the other side, while one rib of the trihedral rib shall be opposite to the other two sides. The slope of two adjacent ribs of the tetrahedral rib shall be opposite to the other two sides.
5.2.1.3 The included angle β between the rib centerline and steel bar longitudinal axis of dihedral rib and trihedral rib shall be 40°~ 60°. The included angle between the rib axis of dihedral rib and steel bar axis shall be 40° to 70°, the angle between two rows of ribs may be 35° to 75°
5.2.1.4 The slope α between the two sides of dihedral rib and trihedral rib and the surface of steel bar, shall not be less than 45°, while that of tetrahedral rib shall not be less than 40°. The rib and surface of steel bar shall intersect in the shape of curve.
5.2.1.5 The sum of rib spacing between dihedral rib and trihedral rib shall not be greater than of the nominal perimeter, and the sum of rib spacing of tetrahedral rib shall not be greater than of the nominal perimeter.
5.2.1.6 The relative rib area fr shall be determined according to Formula (1):
(1)
Where,
K=2, 3 or 4 (dihedral rib, trihedral rib or tetrahedral rib)
FR——longitudinal cross section area of one rib, in square millimeter (mm2);
β——included angle between rib and steel bar axis, in degree (°);
d——nominal diameter of steel bar, in millimeters (mm);
l——rib spacing, in millimeters(mm).
Given the geometric parameter of steel bar, the relative rib area may also be calculated by approximate formula below:
(2)
Where;
——sum of rib spacing on each steel bar periphery, in millimeters (mm);
h—— rib midpoint height, in millimeters (mm);
h1/4——1/4 height of the rib, in millimeters (mm).
5.2.2 The shape of dihedral ribbed steel bar shall comply with the rules in Figure 1 and 5.2.1.
Contents of GB/T 13788-2017
Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Classification, designation
5 Dimension, appearance, weight and allowance deviation
6 Technical requirements
7 Test method
8 Inspection rules
