Classification of steel rebars

There are many types of rebar, usually classified by chemical composition, production process, rolling shape, supply form, diameter size, and use in the structure:

1. According to the diameter

Steel wire (diameter 3~5mm), thin steel bar (diameter 6~10mm), thick steel bar (diameter greater than 22mm).

2. According to mechanical properties

Class I rebar (300/420); Class II rebar (335/455); Class III rebar (400/540) and Class IV (500/630)

3. According to the production process

Hot-rolled, cold-rolled, cold-drawn steel bars, as well as heat-treated steel bars made of grade IV steel bars, have higher strength than the former.

4. According to the role in the structure

Compression bars, tension bars, erecting bars, distribution bars, stirrups, etc.

The steel bars arranged in reinforced concrete structures can be divided into the following types according to their functions:

① Stressed bar – steel bar that bears tensile and compressive stress.

② Stirrups – bear part of the oblique tensile stress and fix the position of the stress bars, which are mostly used in beams and columns.

③ Frame erection bars – used to fix the position of the steel hoop in the beam to form the steel skeleton in the beam.

④Distribution ribs – used in roof slabs and floor slabs, arranged vertically with the reinforcing bars of the slabs, evenly transferring the weight to the reinforcing bars, fixing the position of the reinforcing bars, and resisting thermal expansion and contraction caused by temperature deformation.

⑤Others – Structural ribs configured due to structural requirements of components or construction and installation needs. Such as waist bars, embedded anchor bars, prestressed bars, rings, etc.

5. According to rolling shape

①Smooth steel bars: Grade I steel bars (Q300 steel bars) are all rolled into a smooth round section, and the supply form is coiled, with a diameter of not more than 10mm and a length of 6m~12m.

② Ribbed steel bars: There are three types of spiral, herringbone and crescent shapes. Generally, grade II and III steel bars are rolled into a herringbone shape, and grade IV steel bars are rolled into a spiral shape and a crescent shape. Crescent rib reinforcement: The longitudinal section of the transverse rib is crescent-shaped and does not intersect with the longitudinal rib. ③ Steel wire (divided into low carbon steel wire and carbon steel wire) and steel strand.

④Cold-rolled and twisted steel bars: cold-rolled and cold-twisted.

The smooth round steel bar is actually the small round steel and coil of ordinary low carbon steel. Deformed bars are surface-ribbed bars, usually with 2 longitudinal ribs and transverse ribs evenly distributed along the length. The shape of the transverse rib is spiral, herringbone and crescent shape. Expressed in millimeters of nominal diameter. The nominal diameter of deformed bars corresponds to the nominal diameter of smooth round bars of equal cross-section. The nominal diameter of the rebar is 8-50 mm, and the recommended diameters are 8, 12, 16, 20, 25, 32, and 40 mm. Steel grades: 20MnSi, 20MnV, 25MnSi, BS20MnSi. Reinforcing bars are mainly subjected to tensile stress in concrete. Due to the action of ribs, deformed steel bars have greater bonding ability with concrete, so they can better withstand the action of external forces. Steel bars are widely used in various building structures. Especially large, heavy, light thin-walled and high-rise building structures.

6. By diameter:

Steel wire (diameter 3~5mm), thin steel bar (diameter 6~10mm), thick steel bar (diameter greater than 22mm).

7. According to the structure function:

Compression bars, tension bars, erecting bars, distribution bars, stirrups, etc.

Reinforcing bars are now widely used in any building, which provides better evidence for the progress of human beings. It is also the inspection of the quality of steel bars. When the components are reinforced according to the minimum reinforcement ratio, the steel bars are replaced according to the principle of (equal area).

The mechanical properties of steel bars shall meet the requirements of the following table