Rebar or reinforcement steel is used in concrete to compensate for its low tensile
strength.The steel used for this purpose in reinforced concrete structures comes in the
form of wire or rebar and is called rebar steel.Of course, in specific cases, structural
steel such as channels or hollow sections is also used to reinforce concrete.
In different countries, rebar steel is produced according to various standards and Each
standard includes a specific classification related to the mechanical properties of the
steels.In Iran, the majority of rebar steels produced by the Esfahan Steel Company
conform to Russian standards.
Manufacturers’ standards also vary in terms of the diversity of rebar diameters they
produce.In the Russian system used in Esfahan Steel Company factories, rebar steels
are produced up to a diameter of 40 millimeters.
Various types of rebar and their mechanical specifications:
attributes and is classified, manufactured, and employed as outlined below in Iran. This
classification adheres to the Russian standard, which is widely adopted in Iran.
1-Soft rebar without ribs(A1)
The rebar with a yield strength of 2300 kilograms per square centimeter, a tensile
strength of 3800 kilograms per square centimeter, and a plastic strain (Fracture point)
of 25% is recognized as soft rebar. It is predominantly smooth and ribless.
This type of rebar is suitable for blacksmithing, deformation, and welding operations.
Generally, it is recognized as a ductile rebar.
2-Semi-hard rebar with plain ribs (A2)
This type of rebar, with a yield strength of 3000 kilograms per square centimeter, a
tensile strength of 5000 kilograms per square centimeter, and a plastic strain (Fracture
point ) of 19%, is recognized as semi-hard rebar. It is characterized as semi-brittle and
semi-ductile, typically with ribbed patterns, primarily helical ribs.
This type of rebar is suitable for construction operations, especially Concrete
Reinforcing. Welding operations can be performed on it if necessary, although it is
advisable to avoid welding whenever possible.
3-Hard rebar with intricate ribs (A3)
This type of rebar, with a yield strength of 4000 kilograms per square centimeter, a
tensile strength of 6000 kilograms per square centimeter, and a plastic strain ( Fracture
point)of 14%, is suitable for industrial civil and construction operations. It is
characterized as dry (brittle) rebar, typically with ribbed patterns, mainly helical ribs and
This type of rebar is not suitable for blacksmithing or extensive deformations with
sharp angles, and welding operations on it are strictly prohibited.
4-Hard rebar with complex ribs (A4)
They have spindle-shaped ribs pattern . According to Iranian National Standard
Organization Standard No. 3132, A4 rebar or rebars with ribs 520 and 500 are of the
composite rib type.They have transverse spindle-shaped ribs on both sides, forming a
four-and-a-half pitch in a seven to eight shape, with an angle ranging from 35 to 75
degrees.It guarantees a minimum tensile strength of 520 megapascals and a minimum
elongation of 18% for this grade of its products.The use of A4 rebar with a yield
strength of 500 and 520 megapascals is referred to as rebar with ribs 500 and ribs 520,
respectively, The design and construction of all types of reinforced concrete building
structures (excluding non-building structures), except for special shear walls and
special moment frames, have been approved under the following conditions:
-The rebar must have transverse spindle-shaped ribs on both sides of the longitudinal
rib.
-The ductility of the rebar should be at least as expected for A3 rebar, with a minimum
elongation of 16% over a length equivalent to 5 times its diameter.
-In rebar production, high-carbon bullion should not be used. The rebar production
method should be Thermex technology, and the carbon equivalent (CE) of the rebar
should be a maximum of 0.5.
-In rebar production, high-carbon bullion should not be used. The rebar production
method should be Thermex technology, and the carbon equivalent (CE) of the rebar
should be a maximum of 0.5.
The appearance of the rebars A2 and A3
In foundation design, A3 rebar is used for longitudinal reinforcement and A2 rebar for
transverse reinforcement. One way to identify them is by the shape of the ribs.In A3
rebars, the ribs are in a cross pattern, while in A2 rebars, they are individual.In A2
rebars, the ribs are parallel, while in A3 rebars, they form a seven and eight pattern.
Types of rebar according to standard and current analysis
- -Plain rebar 240
- -Ribbed rebar 340 (helical ribbed rebar) or (uniform)
- -Ribbed rebar 350 (helical ribbed rebar) or (uniform)
- -Ribbed rebar 400 (twisted ribbed rebar) or (uniform)
- -Ribbed rebar 420 (twisted ribbed rebar) or (uniform)
- -Ribbed rebar 500 (composite ribbed rebar)
- -Ribbed rebar 520 (composite ribbed rebar)
Currently, all rebar types in the market adhere to this standard. When you hear the name “A2
rebar,” know that it refers to the same as ribbed rebar 340, and when you hear “A3 rebar,” it
refers to ribbed rebar 400. Only the names remain fixed, but their analysis and standards are
completely different.
In ribbed rebar 340, the ribs are at a 45-degree angle and helically arranged. In ribbed
rebar 400, the angle of the ribs is also 45 degrees, but when viewed from the front, the
ribs are helical (seven and eight pattern).
Mechanical Properties of Rebars – Testing, Tension, and Bending
Yield stress
The maximum force applied to the rebar that does not cause permanent deformation. If
the force increases beyond this point, the rebar will not return to its original shape and
will undergo permanent deformation.The ability to return to the original shape is called
elastic property, and the inability to return to the original shape is called plastic
property.In designs, the criterion for selecting rebar is the amount of yield stress.
Therefore, due to this very important property, the yield stress value is involved in
naming rebars. In Rebar tread 340, the minimum yield stress of this rebar is 340
megapascals (MPA).
Tensile strength
Tensile strength is the maximum tensile force a material can withstand before breaking.
Its unit is pounds per square inch. The tensile strength property of rebars can be
increased through operations such as alloying, cold working, or heat treatment.You
should also be aware of the required quantity and type of rebar (A1, A2, A3, A4).
Without this information, you might receive a different grade or size. In such cases,
most factories do not accept returns or exchanges for incorrect orders.
