The specifications of rebar should include the standard grade, the nominal diameter of the steel bar, the little weight (mass), the specified length and the tolerance value of the above indicators, etc.

The nominal diameters in Chinese standards are 6, 8, 10, 12, 16, 20, 25, 32, 40, 50mm. The supply length is divided into two types: fixed length and double length.

The fixed length selection range of rebar exported from China is 6~12m; the fixed length selection range of rebar produced in Japan is 3.5~10m. In China, if there are no requirements specified in the contract for domestically produced rebar for domestic sales, the lengths are usually 9m and 12m.

1) Nominal diameter range and recommended diameter

The nominal diameter range of steel bars is 6 to 50mm, and the standard recommended nominal diameters of steel bars are 6, 8, 10, 12, 14, 16, 20, 25, 32, 40, and 50mm.

2) Permissible deviations in surface shape and size of ribbed steel bars

The design principles of ribbed steel bar transverse ribs should comply with the following regulations:

The angle β between the transverse rib and the axis of the steel bar should not be less than 45 degrees. When the angle is not greater than 70 degrees, the directions of the transverse ribs on the opposite sides of the steel bar should be opposite;

The nominal spacing l of transverse ribs shall not be greater than 0.7 times the nominal diameter of the steel bar;

The angle α between the side of the transverse rib and the surface of the steel bar shall not be less than 45 degrees;

The total gap (including the width of the longitudinal ribs) between the ends of the transverse ribs on two adjacent surfaces of the steel bar should not be greater than 20% of the nominal circumference of the steel bar;

When the nominal diameter of the steel bar is not greater than 12mm, the relative rib area should not be less than 0.055; when the nominal diameter is 14mm and 16mm, the relative rib area should not be less than 0.060; when the nominal diameter is greater than 16mm, the relative rib area should not be less than 0.065. For the calculation of relative rib area, please refer to Appendix C.

Ribbed steel bars usually have longitudinal ribs or may not have longitudinal ribs;

3) Length and allowable deviation

a. Length

Steel bars are usually delivered in fixed lengths, and the specific delivery length should be specified in the contract;

Steel bars can be delivered in coils, and each coil should be one steel bar. It is allowed that 5% of the number of coils in each batch (two coils if less than two coils) are composed of two steel bars. The disc weight and disc diameter are determined by negotiation between the supply and demand parties.

b. Length tolerance

The allowable length deviation of steel bars when delivered to fixed length shall not be greater than ±25mm;

When the minimum length is required, the deviation is +50mm;

When the maximum length is required, the deviation is -50mm.

c. Curvature and ends

The ends of the steel bars should be sheared straight, and local deformation should not affect use.

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