The main reinforcement generally refers to the reinforcement bearing gravity load in concrete members. Compared with structural reinforcement, it is also called longitudinal stress reinforcement. Bending members that are only arranged in the tension area of the section are called single-rib bending members, and bending members that are arranged in the compression area of the section are called double-rib bending members. Therefore, according to their different forces, there are two kinds of main reinforcement: the main reinforcement in tension bears tensile stress and the main reinforcement in compression bears compressive stress.

Stirrup: used to meet the shear strength of inclined section and connect the main reinforcement in the compression area with the reinforced concrete frame. There are single-limb stirrups, open rectangular stirrups, closed rectangular stirrups, rhombic stirrups, polygonal stirrups, square stirrups and circular stirrups. Stirrups should be determined according to calculation, and the minimum diameter of stirrups is related to the beam height h, when h≦800mm, it should not be less than 6 mm; When H> is 800 mm, it should not be less than 8 mm. ..

The stirrups at the beam supports are generally set 50mm away from the beam side (or wall side). For reinforced concrete independent beams supported on masonry structures, the anchorage length of longitudinal reinforcement in Las should not be less than two stirrups. When the beam is integrally connected with the concrete beam or column, stirrups are not needed in the bearing.

Most distribution bars appear on the floor. The distribution bar is located 90 degrees above the stress bar to fix the position of the stress bar and distribute the load on the board to the stress bar. At the same time, it can also prevent cracks from occurring in the direction perpendicular to the stressed steel bars due to concrete shrinkage and temperature change. On shear walls, the longitudinal reinforcement and transverse reinforcement of walls other than wall beams and columns are also called distribution reinforcement.

Extended data:

The main bars in the beam are: longitudinal bars at the upper and lower parts of the beam; Longitudinal through and non-through steel bars at the upper part of the bearing; Anti-twisting waist tendon;

The main reinforcement in the slab includes: through and non-through reinforcement in the upper part of the slab support, and longitudinal reinforcement in the lower part;

The main reinforcement in the wall is: horizontal and vertical reinforcement in the wall;

The main reinforcement in the column are: longitudinal reinforcement of the column;

The number of stirrups is the number of stirrups in the same section height direction of the beam.

Because the width of the small-section beam is small and the corresponding shear force in the beam is small, the single-limb hoop can be used, which is similar to the S-hook.

Like a single closed stirrup, there are two steel bars in the height direction, which belong to the double limb hoop.

For another example, two closed hoops are used in the same section with a wide section, and there are four steel bars in the height direction, which belong to four limb hoops.

According to GB500 10-2002, in the cast-in-place slab area with large temperature and shrinkage stress, the spacing of reinforcement should be 150~200MM, and the temperature shrinkage reinforcement should be arranged on the unreinforced surface of the slab.

The temperature shrinkage reinforcement can be arranged through the original reinforcement, or a separate steel mesh can be set. The length calculation of the temperature shrinkage reinforcement is the same as the distribution reinforcement of the negative reinforcement in the plate. When the temperature reinforcement is designed on the drawing, it can be calculated with reference to the length of the distributed reinforcement. As follows:

1, temperature reinforcement length = axis length-negative reinforcement marked length on both sides+lap length *2+ hook *2, with or without hook *2, according to the reinforcement grade, grade I reinforcement can be added or not, and grade II and III reinforcement can be added without hook;

2. Number of temperature steel bars = (axis length-length of negative bars on both sides)/spacing of temperature steel bars-1 accurate; But sometimes the reinforced bar can play the role of temperature reinforcement, and the distributed reinforcement does not appear alone in the plate, but is arranged inside the reinforced bar and perpendicular to the reinforced bar.

The function is to fix the position of the reinforced bar, distribute the load on the plate to the reinforced bar, and prevent cracks perpendicular to the reinforced bar due to the shrinkage and temperature change of concrete.

References:

Baidu encyclopedia-main reinforcement

References:

Baidu encyclopedia-stirrup

References:

Baidu encyclopedia-delivery spareribs