There are many kinds of reinforcing bars, which are usually classified according to chemical composition, production process, rolling shape, supply form, diameter and size, as well as the use in the structure. Here we mainly sort out the classification according to the use.
1. force bar
Refers to the lower part of a beam or slab, the part of steel bars that bear tension and the shear-resistant bending bars, suspension bars, etc. How to distinguish the stress ribs from the distribution ribs?
(1) Distinguishing by the spans of the slabs: If it is a single slab, the steel bar parallel to the short span direction is the force bar, and the steel bar parallel to the long span direction is the erection bar. If it is a two-way slab, then the long-span and short-span direction of the reinforcement are all force bars.
(2) Distinguishing by the diameter of reinforcing bars: the larger the diameter of reinforcing bars, the smaller the diameter of reinforcing bars, the distribution of reinforcing bars;
(3) Distinguish by layout: the steel bar with positive moment bar is the stress bar, the steel bar with vertical distribution is the distribution bar, the negative moment bar (such as cantilever plate) is the opposite, the steel bar with lower moment bar is the distribution bar, and the steel bar with upper moment bar is the stress bar.
2. distributing tendons
Appears in the board, is arranged in the upper part of the stressed steel bar, and is perpendicular to the stressed steel bar. The function is to fix the position of the stressed steel bar and distribute the load on the slab to the stressed steel bar. At the same time, it can prevent the cracks in the direction perpendicular to the stressed steel bar due to the shrinkage and temperature change of the concrete. It belongs to the structural steel bar. (To satisfy the structural requirements, for various factors that are not easy to calculate and are not taken into account, the steel bars set up are structural steel bars.)
It is used to satisfy the shear strength of oblique section and to connect the tension main steel bar and the concrete in compression zone to work together. In addition, it is used to fix the position of the main steel bar and make the various steel bars in the beam form the steel bar skeleton. It is a circular (circular and rectangular) steel bar with shear resistance of beams and columns. It is an oral shape. It fixes the upper and lower steel bars and resists shear at the same time.
4. vertical reinforcement
It is the steel bar on the upper part of the beam, which only plays a structural role and has no substantial significance, but at both ends of the beam, the erecting bar on the upper part resists negative bending distance, which is indispensable. (The erecting steel bar is set on both sides of the outer edge of the compression zone of the beam to fix the stirrups and form the steel bar skeleton. If the compression area is equipped with longitudinal compression steel bar, erecting steel bar can be no longer equipped. The diameter of the erecting steel bar is related to the span of the beam.
5. through tendon
It refers to the reinforcing bar that runs through the whole length of a member (such as a beam) without bending or interrupting. When the reinforcing bar is too long, it can be lapped or welded without changing the diameter.
What is the difference between erecting tendons and perforating tendons?
In the arrangement of reinforcing bars, erecting reinforcing bars are 1/3 of the span, that is to say, there are left and right support reinforcing bars in the span beam. The long reinforcement bar is the long layout. The erecting reinforcement acts as a erecting force and has a certain compressive effect, which can improve the bearing capacity of the beam to a certain extent.
The through bar refers to the reinforcing bar that runs through the whole length of a member (such as a beam) without bending or interrupting. When the reinforcing bar is too long, it can be lapped or welded without changing the diameter. The through bar can be either a force steel bar or a frame steel bar. For example, in the code, the stiffeners on both sides of the upper part of the beam must be through. At this time, the stiffeners can also bear some negative bending moments at the support.
If there are long reinforcing bars above and below the beam, generally in the beam (compression zone) and the diameter of the smaller is the frame reinforcement, under the beam are all stressed steel bars.
6. negative reinforcement
The definition of bending moment is that the lower part of the steel bar is tensioned positive, while the upper part of the beam and slab position is generally tensioned on the upper part of the support seat according to the force, that is, to bear negative bending moment, so it is called negative bending moment steel bar. (Bearing with negative reinforcement, is relatively speaking, should generally refer to the support part of the beam to offset negative bending moment of the reinforcement, commonly known as load-bearing reinforcement. The bending moment of general structural members can be divided into positive moment and negative moment. The steel bars equipped to resist negative moment are called negative bars. The upper bars of finger plates and beams are generally referred to as negative bars. When the upper reinforcing bars of beams and slabs are long, they are also customarily referred to as the upper reinforcing bars, and the gluten of beams or slabs is the negative reinforcing bars.
7. tie bars
Tensile reinforcement is reserved between two or more components that cannot be constructed at the same time. It is a reinforced bar that strengthens the connection between frame filled wall and column, and improves the stability and seismic capacity of filled wall.
8. web reinforcement
一般位于梁两侧中间部位而得来的，是梁中部构造钢筋,主要是因为有的梁太高，需要在箍筋中部加条连接筋 （梁侧的纵向构造钢筋实际中又称为腰筋）。在梁高450mm，就应沿梁高两侧应设腰筋，所以数量上就不会少于2根。腰筋的直径小的直径为10mm，间距不应大于200mm，同时面积配筋率不应小于百分之0.3，在梁两侧的纵向构造钢筋（腰筋）之间还要配置拉结钢筋。 一般民用建筑的腰筋直径用16和18就可以了，拉筋用圆8。
Generally located in the middle part of both sides of the beam, the structural steel bar in the middle of the beam is obtained, mainly because some beams are too high and need to add a connecting bar in the middle of the stirrup (the longitudinal structural steel bar in the side of the beam is also known as the waist bar in practice). In the 450mm beam height, waist reinforcement should be installed along both sides of the beam height, so the number will not be less than two. The minimum diameter of waist reinforcement should be 10 mm, the spacing should not be greater than 200 mm, and the reinforcement ratio of area should not be less than 0.3%. Tensile reinforcement bar should also be arranged between longitudinal structural reinforcement bar (waist reinforcement) on both sides of the beam. The diameter of waist tendons in general civil buildings should be 16 and 18, and the diameter of tension tendons should be 8.