1, steel processing should be carried out in a special processing plant.
2, the surface of the steel bar should be clean, no damage, oil stains, paint stains and rust should be removed before processing. Steel bars with granular or flaky old rust shall not be used. If there are serious surface defects in the steel bars after derusting, the mechanical properties and other related performance indexes of this batch of steel bars should be re-inspected.
3, steel processing must be carried out at room temperature, steel processing should not be heated. Bending of steel bars should be completed at one time, and repeated bending is not allowed.
4. Steel bars shall be straightened by mechanical equipment without extension function or cold drawing. When straightening by cold drawing method, the cold drawing rate of HPB235 and HPB300 round steel should not be greater than 4%;
The cold-drawn rate of HRB335, HRB400, HRB500, HRBF335, HRBF400, HRBF500 and RRB400 ribbed bars should not be greater than 65438 0%. The transverse ribs of ribbed steel bars should not be damaged in the process of steel bar straightening. Straightened steel bars should be straight, and there should be no local bending.
5. Steel bar bending shall meet the following requirements:
(1) The end of the round steel bar should be hooked at 180, and the length of the straight part after the hook is bent should not be less than 3 times the diameter of the steel bar. When used as compression reinforcement, the end of round steel shall not be hooked;
(2) The curved inner diameter of smooth round steel bar should not be less than 2.5 times the diameter of steel bar;
(3) The bending inner diameter of 335 MPa and 400MPa ribbed bars should not be less than 5 times the diameter of the bars;
(4) The bending inner diameter of 500MPa ribbed bar with a diameter less than 28mm should not be less than 6 times of the diameter of the bar, and the bending inner diameter of 500MPa ribbed bar with a diameter of 28mm and above should not be less than 7 times of the diameter of the bar;
(5) At the top node of the frame structure, when the steel bar diameter is less than 28mm, the inner diameter of bending arc should not be less than 12 times of the steel bar diameter, and when the steel bar diameter is 28mm or more, the inner diameter of bending arc should not be less than 16 times of the steel bar diameter;
(6) The inner diameter of stirrup bending arc should not be less than the diameter of longitudinal reinforced bar.
6. Except welding closed stirrups, the ends of stirrups and lacing bars shall be hooked according to the design requirements. When the design has no specific requirements, it shall meet the following requirements:
(1) The bending inner diameter of stirrups and lacing hooks shall comply with the provisions of Article 5 of this specification;
(2) For general structural members, the bending angle of stirrup hook should not be less than 90, and the length of straight part after bending should not be less than 5 times of stirrup diameter; For structural members with special requirements for seismic fortification and design, the bending angle of stirrup hook should not be less than 135, and the length of straight part after bending should not be less than 10 times the stirrup diameter and the larger value of 75mm;
(3) The lap length of cylindrical stirrups should not be less than the anchorage length of steel bars, and both ends should be hooked at 135. After bending, the length of the straight part, the general structural members should not be less than 5 times of the stirrup diameter, and the structural members with seismic fortification requirements should not be less than 10 times of the stirrup diameter;
(4) The bending angle of the hooks at both ends of the brace should not be less than 135, and the length of the straight part after bending should not be less than 10 times the diameter of the brace.
7. Flash butt welding, gas welding or single-sided lap welding shall be adopted for welding closed stirrups, and special equipment shall be used for welding. The blanking length and end processing of welded closed stirrups should be determined according to different welding processes.
The solder joint setting of polygon welded closed stirrup shall meet the following requirements:
(1) The number of solder joints of each stirrup should be 1, and the solder joints should be located in the middle of one side of the polygon stirrup, and the distance from the stirrup bend should not be less than100 mm; ;
(2) The stirrups of rectangular columns should be located on the short side of the columns, and the stirrups of equilateral polygonal columns can be located on any side; The stirrups of equilateral polygonal columns should be processed into two types, and the solder joints are on different sides;
(3) The welding points of beam stirrups should be set at the top or bottom edge.
Extended data:
The main process of steel bar processing is very important, and the process is formulated to better handle the construction details and ensure the final quality.
1, steel bar straightening
The straightening of round steel is generally carried out by winch or grinder, or by steel bar straightening machine. After the steel bar is straightened, it will be cut into the required length according to the ingredient list. For some steel bars with a diameter of 20 mm, manual straightening and straightening are often used on the workbench. The rest shall be straightened by a steel bar straightener.
When the steel bar is straightened by hoist, the straightening cold-drawn rate of Grade I steel bar is 4 ~ 6%, 1. Grade II reinforcement is 3%, generally at least until the floating skin on the surface of reinforcement falls off. In the structure where cold-drawn steel bars are not allowed, the straightening cold-drawn rate of steel bars should not be l%. Straightened steel bars shall be straight without local bending.
2, steel bar cut off
Steel bar cutter is used for cutting steel bars. When cutting materials, it is necessary to avoid measuring long materials with a short ruler to prevent the accumulation of errors in measuring materials. To prevent the accumulation of errors in measurement. For this reason, the scale line of size is marked on the workbench, and a baffle is set to control the size of broken materials. Steel bars of the same specification should be matched according to different lengths and arranged as a whole. Generally, the long material is broken first, and then the short material is broken to reduce the short head and loss.
In the process of cutting, if the steel bar is found to be split, shrunk or severely bent, it must be removed; If there is a big discrepancy between steel bar hardness and steel grade, it should be reported to relevant personnel in time to find out the situation.
After heat treatment, the steel bars can be cut mechanically, but not by electric arc (except tensile cutting), so as to avoid low stress brittle fracture of steel bars caused by ignition. The fracture of reinforcement should not be horseshoe-shaped or bent. The length of reinforcement should be as accurate as possible, and the allowable deviation should be in accordance with the relevant regulations according to the different uses of reinforcement.
References:
Xichong County People's Government-Code for Construction of Concrete Structure Engineering
References:
Pingshan, Shenzhen-Main working procedures of steel bar processing