What Is Steel Rebar?

Rebar symbols refer to the rebar parameter symbols and so on. The unit of measurement for the theoretical weight of steel is kilograms (kg). When rebar processing is made, check the rebar processing table and the design drawing, and check whether there are errors and omissions in the blanking table.

Rebar symbol

The unit of measurement for the theoretical weight of steel is kilograms (kg). Its basic formula is:

1. Rebar production When rebar processing is performed, check the rebar processing table and design drawings , and check whether there are errors and omissions in the blanking table. Each steel bar must be checked according to the billing table to determine whether the requirements are met. Then press the material table to release the real samples, and the batches can be produced after the trial production is qualified. The processed steel bars must be listed and stacked neatly and orderly.

When steel bar replacement is required during construction, the design intention and material properties must be fully understood, and various regulations of the current reinforced concrete design code must be strictly observed. High-strength steel bars of the same area cannot be replaced with low-strength steel bars. The replacement of steel bars at important parts must be agreed by Party A and the design unit, and can only be replaced with written notice.
(1) The surface of the steel bar should be clean, and the adhered oil, dirt, and floating rust must be cleaned before use. It can be combined with the cold drawing process to remove rust.
(2) Straightening of steel bars can be straightened mechanically or manually. The straightened steel bars must not have local bends, dead bends, or small wavy shapes, and their surface flaws should not reduce the cross section of the steel bars by 5%.
(3) Rebar cutting should be based on the number, diameter, length and number of rebars, and the length and length should be matched. The long material should be broken first and then the short material should be broken to minimize and shorten the short steel bar to save steel.
(4) Reinforced hook or bend:
Reinforced hook. There are three forms, namely semi-circular hook, straight hook and oblique hook. After the rebar is bent, the inner end of the bend shrinks, the outer skin extends, and the axis length does not change. An arc is formed at the bend. The size after bending is not larger than the cut-out size. Bending adjustment values should be considered.
The diameter of the rebar bending center is 2.5d, and the straight part is 3d. Theoretical calculation of the length of the reinforced hook: 6.25d for the semicircular hook, 3.5d for the straight hook, and 4.9d for the diagonal hook.
Bend the reinforcement. The bending diameter D at the bend at the middle part is not less than 5 times the diameter of the reinforcing bar.
stirrups. The ends of the stirrups should be hooks, and the hook form should meet the design requirements. Stirrup adjustment, that is, the difference or sum of the increase in length of the hook and the bending adjustment value, is determined according to the size of the stirrup amount or the size of the inner wrap.
The blanking length of steel bars shall be comprehensively considered in accordance with regulations such as component size, concrete protective layer thickness, steel bar bending adjustment value, and increased hook length.
a. Cutting length of straight steel bars = length of componentthickness of protective layer + increased length of hooks b. Cutting length of steel bar when bending ups = Straight length + inclined bending lengthBending adjustment value + increased length of hooks c. Cutting of stirrups Length = perimeter of stirrups + adjustment value of stirrups + increase in hook length 2. Rebar binding and installation:
Before tying up the reinforcing steel bars, familiarize yourself with the drawings carefully, check whether there is any discrepancy between the ingredients list, the drawings, and the design, and carefully check whether the finished product size and heart are consistent with the blanking table. Checking is correct before banding.
20 # iron wire is used to bind steel bars with diameter above 12 and 22 # iron wire is used to bind steel bars with diameter below 10.
(1) Wall The reinforcement mesh of the wall is tied with the foundation. When the steel bar has a 90 ° hook, the hook should face the concrete.
When using a double-layer reinforced mesh, a brace (hook) should be installed between the two layers of reinforcement to fix the distance between the reinforcements.
When binding the wall bars, the verticality should be controlled by hanging wires, and the spacing of the main bars should be strictly controlled. The three levels on the lower and upper sides of the shear wall should be fully tied, and the rest can be tied up with plum blossoms.
In order to ensure the correct position of the reinforcing bar, a horizontal or hoop bar is tied outside the vertical force bar, and it is spot welded with the vertical bar to fix the position of the wall and column bar. When the spot welding is fixed, use a wire hammer .
It is strictly forbidden to open the hole after the external wall is poured. All the embedded parts and buried pipes at the entrance of the hole shall be reserved. See the construction drawing for the reinforcement of the hole. Rebars are reserved in the walls and columns for lightning protection grounding leads, and they should be welded into channels. The location, quantity and method are detailed in the installation and construction drawings. Welding work should be carried out by qualified welders. The structural steel bars must not be damaged. The hydropower installation must be pre-buried.
(2) Beams and slabs When there is a double-layered or multi-layered arrangement of longitudinally-stressed steel bars, a short steel bar with a diameter of 15mm should be placed between the two rows of steel bars. If the vertical steel bar is larger than 25mm, the diameter of the short steel bar is the same as the vertical steel bar. specification.
The joints of stirrups should be staggered and tied with two stand-up stirrups. The cantilever cantilever beam has the stirrup joints below, and the rest is the same as the column. The outer corner of the main beam of the beam should be fully tied with the stirrups, and the rest can be tied with plum blossoms.
The reinforcement of the steel mesh of the plate is the same as that of the foundation. Attention should be paid to the negative reinforcement at the upper part of the board (surface reinforcement) to prevent it from being stepped down; especially for cantilever boards such as awnings, canopies and balconies, the position and height of the negative reinforcement must be strictly controlled.
Where the slab, secondary beam and main beam cross, the reinforcement of the slab is on top, the reinforcement of the secondary beam is on the middle floor, the reinforcement of the primary beam is on the bottom, and when there is a ring beam or cushion beam, the reinforcement of the primary beam is on.
The starting point of the bending of the floor slab. If the processing plant (field) has no bending in the design, and the design drawing is not specifically noted, the steel can be bent according to the following regulations. The edge support of the slab is bent according to the span of 1 / 10L. starting point. The mid-span and continuous multi-span of the board can start from the center line of the support 1 / 6L. (Lthe middle and middle span of the board).
When the steel bars are very densely interspersed at the joints of the frame beams, it should be noted that the net distance between the main bars on the top surface of the beams must be 30mm to facilitate the need for concrete placement.
The lashing joints of steel bars shall meet the following requirements:
1) The end of the overlap length is not less than 10 times the diameter of the reinforcing bar, and the joint should not be located at the maximum bending moment of the component.
2) In the area of tension, the ends of the class steel bar lashing joints should be hooks, and the class steel bars can be omitted.
3) The overlap of steel bars should be fastened with iron wire at the center and at both ends.
4) The overlap length of the tensioned steel bar lashing joints shall meet the structural design requirements.
5) The thickness of the reinforced concrete protective layer shall meet the structural design requirements.
6) Before binding the steel bars, you must first elastically line the cables according to the design drawings and bind them according to the lines to control the quality.
7) In order to ensure the correct position of the reinforcing bars, according to the design requirements, the ribs are supported by a reinforced horse stool crossbar @ 600.
3. Rebar connection length:
According to the design requirements, mechanical reinforcement and sleeve extrusion connection technology are preferred for the steel bars with a diameter of 18 in this project. The remaining steel bars are extended. Butt welding and arc welding are used for horizontal bars, and electroslag pressure welding is used for vertical bars. Vertical steel bars larger than 25 are connected by sleeve extrusion.