Reinforced Bars

Hot-rolled steel serves for additional reinforcement of reinforced concrete structures.

This technical standard covers hot-rolled round steel bars of both smooth and ribbed profile patterns, intended for reinforcing normal and pre-stressed reinforced concrete structures (reinforcing steel). In terms of the standards for the chemical composition of low alloyed steels, the standard also applies to to ingots, blooms, and slugs.

Reinforcing Steel of the Ribbed Profile Pattern
Bars with lateral ribs, evenly disposed on the surface, intended to improve bonding with the concrete.

Reinforcing Steel of the Smooth Profile Pattern.

Smoothly surfaced round bars with no grooving intended to improve bonding with the concrete.

Strength Grade

A strength grade is a standard-based value of the physical or constraint yield point of the steel.

Inclination Angle of Lateral Ribs
The angle between the lateral ribs (grooving) and the longitudinal axis of a bar.

Pitch of Lateral Ribs
The distance between the centers of two sequential lateral ribs measured parallel to the longitudinal axis of a bar.

Height of Lateral Ribs
The distance from the extreme point of a lateral rib up to the surface of the bar core measured orthogonally to the longitudinal axis of a bar.

Nominal Diameter of Ribbed Reinforcing Steel Bars
The diameter of the equal-sized cross-sectional area of a round smooth bar.

Cross Section Nominal Area
The area of the cross section, equivalent to the area of the cross section of a round smooth bar with the same nominal diameter.

GOST (State Standard) 10884-81
Thermo-mechanical and thermally enhanced ribbed steel bars with the diameter within the range of 6-40 mm are intended for the construction of critical reinforced concrete structures.
Subject to their mechanical properties, reinforcing bars of this standard are subdivided into the following categories: Ах -III, Ат -IV, Ат -V, Ат -VI, Ат -VII, and Ат -VIII.

Reinforcing bars under this standard are made of the below-listed steel grades

GOST 5781-82

Depending on their mechanical properties, reinforcing steels are subdivided into classes A-I (A240), A-II (A300), A-III (A400), A-IV (A600), A-V (A800), and A-VI (A1000).

A reinforcing steel is manufactured in bars or rolls. Reinforcing steel of of A-I class (A240) is smooth, while steels of classes A-II (A300), A-III (A400), A-IV (A600), A-V (A800), A-VI (A1000) are ribbed. Pursuant to a client’s request and if agreed with the manufacturer, steels of classes A-II (A300), A-III (A400), A-IV (A600), A-V (A800) can be produced with a smooth surface as well.

Reinforcing ribbed steels constitute round structures with two longitudinal edges and cross ribs that run along a triple-threaded helical curve. For sections, having 6 mm in diameter, it is permitted to have the ribs running on a single-threaded helical curve, and for those with 8 mm in diameter, a double-threaded helical curve is allowed.

Reinforcing steel of grade A-II ( А 300) of the standard manufacture patter, specialized as Ас -II ( Ас 300), must have its ribs running on the screw lines, started identically on both sides of the section.

Reinforcing steels of grades A-III (A400), A-IV ( А 600), A-V (A800), and A - VI ( А 1000) must have their ribs on the screw lines, started from the right on one side, and from the left – on the other.

Relative shifting of screw ribs on the sides of a section, divided by longitudinal edges, are not covered by standards.

Reinforcing steels of grades A-I (A240) and A-II ( А 300), with the diameter up to 12 mm, and of grade A-III (A400), with the diameter up to 10 mm, inclusively, are manufactured in coils or bars, and large diameters are offered in bars. Reinforcing steels of grades A - IV ( А 600), A-V (A800), and A-VI (A1000) of all sizes are manufactured in bars. Those with the diameters of 6 mm and 8 mm can be offered in coils if agreed by the manufacturer and the client.

Reinforcing bars are made of carbon and low alloyed steels of the grades specified in the below table. For bars of class A-IV (A600), steel grades are determined by agreement with the client.

Steel Grades for Manufacturing Re-Bars of Various Classes (GOST 5781-82)

Notes:

It is permitted to manufacture a reinforcing steel of class A-V ( А 800) of steel grades 22 Х 2 Г 2 АЮ, 22 Х 2 Г 2 Р and 20 Х 2 Г 2 СР. The sizes specified in brackets are produced by agreement with the consumer.

The West Siberian Iron and Steel Plant produces thermally and mechanically hardened reinforcing steels of grades А 400 С and А 500 С as stipulated by standard 14-1-5254-94. Low carbon contents along with the thermo-mechanical treatment of reinforcement steels in rolls provide for the improved welding characteristics and plasticity as well as hyper-viscosity and long service life. Those reinforcing steels conform to the international standards.

The State Committee for Construction of the Russian Federation (Gosstroi) recommends using reinforcing steels of classes А 400 С and А 500 С for reinforced concrete structures, both in conjunction and instead of the reinforcing steels of class A-III of grades 25 Г2С and 35 ГС (GOST 5781-82) and of class Ат -III С (GOST 10884-81), of the same diameters. Thermo-technical and thermally hardened ribbed steel bars with the diameter range of 6-40 mm are intended for critical reinforced concrete structures (GOST 10884-81).

Rebar Parameters (GOST 5781-82)

Thermally and Mechanically Hardened Heavy Duty Reinforcing Steel Reinforcing for Reinforced Concrete Structures. GOST 10884-94

Reinforcing steels are subdivided into classes according to:

their mechanical properties - into strength grades (established by the standard of the pre-set values of constrained or physical yield point in Newton/mm²); and

their operating characteristics - into welding steel (index С ) and corrosion cracking resistant (index К).

Reinforcing steels can be of classes Ат 400 С, Ат 500 С, Ат 600, Ат 600 С, Ат 600 К, Ат 800, Ат 800 К, Ат 1000, Ат 1000 К, and Ат 1200. When agreed with the client, reinforcing steels of strength grade Ат 800 and higher are allowed to be manufactured in a smooth-surfaced pattern.

Marking:

In the absence of any rolling marks, bars or coils of the reinforcing steel of the appropriate class must be painted with an indelible paint of the following colors:

Ат 400 С - white;
Ат 500 С - white and dark blue;
Ат 600 - yellow;
Ат 600 С - yellow and white;
Ат 600 К - yellow and red;
Ат 800 - green;
Ат 800 К - green and red;
Ат 1000 - dark blue;
Ат 1000 К - dark blue and red;
Ат 1200 - black.

Recommended grades of carbon and low alloyed steels for manufacturing rebars of the respective classes.