Classification of reinforcement
Due to the variety, specification and model of steel bars and their different functions in members, there are often different names in construction. For a steel worker, only if he is familiar with the classification of steel bars, can he clearly understand the performance of steel bars and the role they play in the components, and will not make mistakes in the process of steel bar processing and installation.
There are many classification methods of steel bars, roughly as follows. 1、 According to the role of reinforcement in components
1. Stress bar: refers to the main reinforcement determined according to the calculation in the component, including: tension bar, bending bar, compression bar, etc.
2. Structural reinforcement: refers to the reinforcement set in the component according to the structural requirements, including: distribution reinforcement, stirrup, erection reinforcement, transverse reinforcement, waist reinforcement, etc.
2、 According to the shape of reinforcement
1. Plain round steel bar: the surface of the steel bar is smooth and without lines, mainly used for distributing steel bar, stirrup, wall board steel bar, etc. When the diameter is 6-10 mm, it is generally made into a circle, and the diameter of more than 12 mm is a straight bar.
2. Deformed steel bar: the surface of the steel bar is engraved with different lines, which enhances the bond between the steel bar and the concrete. It is mainly used for the stress bars in columns, beams and other components. The factory length of deformed steel bars is 9m and 12m.
3. Steel wire: it is divided into cold drawn low carbon steel wire and carbon high-strength steel wire, with diameter less than 5mm.
4. Steel strand: there are three strands and seven strands, which are commonly used in prestressed reinforced concrete members.
3、 According to the strength of reinforcement
Hot rolled steel bars are commonly used in reinforced concrete structures. Hot rolled steel bars can be divided into four grades according to their strength. Hpb235 (grade I steel) has a standard value of yield strength of 235mpa; HRB335 (grade II steel) has a standard value of yield strength of 335mpa; HRB400 (grade III steel) has a standard value of yield strength of 400MPa; rrb400 (grade IV steel) has a standard value of yield strength of 400MPa. Hpb235 steel bars are mostly used for the reinforcement of cast-in-place floor slab and stirrup of beam column; HRB335, HRB400 and rrb400 steel bars are mostly used for the stress reinforcement of beam column.