(1) In order to ensure the engineering quality, the raw material (base material) of cold-rolled ribbed steel bar is Q235 high-quality low-carbon steel hot-rolled round wire rod, which is cold-rolled and reduced in diameter and continuously ribbed. Due to cold working hardening, its tensile strength is greatly increased. After cold rolling, the bond strength between ribbed steel bars and concrete is much higher than that of smooth steel bars.
(2) In order to save construction and engineering costs, according to the technical specification for cold-rolled ribbed reinforced concrete structures of China people's * * * and the national industry standard UGJ95-201), CRB550 cold-rolled ribbed steel bars are used to replace about 35% of grade I steel bars per ton, and the strength design value of cold-rolled ribbed steel bars is still taken according to the original regulations.
Second, the application
In the cast-in-place concrete structure of industrial and civil high-rise buildings, cold-rolled ribbed steel bars have the following uses, which conform to the relevant provisions of the current national standard Code for Design of Concrete Structures (GB500 10).
1, main reinforcement and distribution reinforcement of cast-in-place floor slab and stairs. When cold-rolled ribbed steel bars are used as the main reinforcement and distribution reinforcement of cast-in-place floors and stairs, they are easy to bind and fix because of their high stiffness, and are not easy to deform when trampled, thus ensuring the effective position of the steel bars. After binding, the appearance and feel are stretched.
2. Horizontal and vertical distribution of steel bars in the shear wall (welding mesh type is preferred).
3. Stirrups in beams and columns. The plasticity of cold-rolled ribbed steel bars can meet the shear deformation requirements of beams and columns.
4. Reinforcement of ring beam and constructional column. In addition, LL550 cold-rolled ribbed steel bars, especially welded mesh, are also widely used in expressway pavement, airport runway, drainage ditch, tunnel lining and other projects.
Extended data:
Application effect of ribbed steel bar
Cold-rolled ribbed steel bar is an updated product of cold-drawn low-carbon steel wire in prestressed concrete members. In the cast-in-place concrete structure, I-grade steel bars can be used instead to save steel, which is a better kind of cold-worked steel of the same kind. Its performance and application effects are as follows:
China's national standard "Cold-rolled ribbed bars" GB 13788─2000 mechanical performance index LL550 is formulated with reference to international standards and standards of developed countries. The tensile strength is 550Mpa, and the elongation is 8% according to the German standard δ [_ 10] (equivalent to δ[_5] is12-65438).
References:
Baidu encyclopedia-cold rolled ribbed steel bar