How are the ribs of cold rolled ribbed steel bars formed?
The diameter of the cold-rolled ribbed steel bar is reduced by hot-rolled wire rods through multiple cold rollers. After the cold roll pressing, the internal stress is eliminated and the crescent ribbed bar with 2D or 3D is formed. Cold rolled ribbed steel bar is a new product of cold-drawn low carbon steel wire in prestressed concrete members. In cast-in-place concrete structure, it can replace grade I steel bar to save steel. It is a better kind of cold processed steel of the same kind.
Cold rolled ribbed steel bar is a new product of cold drawn low carbon steel wire in prestressed concrete members. In cast-in-place concrete structure, it can replace grade I steel bar to save steel. It is a better kind of cold processed steel of the same kind. Its performance and application effect are as follows
The mechanical property index of LL550 in Chinese national standard “cold rolled ribbed strip” gb13788-2000 is formulated with reference to international standard and developed country standard. The tensile strength is 550MPa and the elongation is standardized in Germany δ From the comparison of these two indexes, the standard of cold-rolled ribbed bar in China is not lower than the international standard.
Cold rolled ribbed bars have the following advantages:
The steel has high strength, which can save construction steel and reduce project cost. Compared with hot-rolled plain round bar, LL550 cold-rolled ribbed bar can save 35% – 40% steel when used in cast-in-place structure (especially in roof). If we don’t use the hook, we need to save more steel. According to the market price of steel, the cost of steel can be saved about 800 yuan per ton of cold-rolled ribbed steel bar.
The bond anchorage performance between cold-rolled ribbed bar and concrete is good. Therefore, when it is used in the component, the phenomenon of cracking in the anchorage zone and steel wire sliding is fundamentally eliminated, and the bearing capacity and crack resistance of the end of the component are improved; In reinforced concrete structure, the crack width is smaller than that of plain round steel bar, even than that of hot rolled thread steel bar.
The elongation of cold-rolled ribbed bar is higher than that of the same kind of cold-rolled steel.