What is the truncation principle of longitudinal reinforcement in a beam

The truncation principle of the longitudinal reinforcement in the beam is that the upper reinforcement of the beam is truncated at 1 3 places from the net span of the beam support, because of the vicinity of the supportShear forcelarge, to resist shear forces; The lower reinforcement of the beam is lapped at the distance from the beam support and cannot be disconnected because of the middle spanBending momentHit, the bending moment near the bearing is small.

When the beam is higher (HW 450mm), in order to prevent concrete shrinkage and temperature deformation and produce vertical cracks, strengthen the stiffness of reinforcement skeleton simultaneously, set up a waist bar with a diameter of not less than 10mm at every 200mm along the beam height on both sides of the beam, and the tension bar of 6 or 8 is connected between the two waist ribs, and the tension spacing is generally stirrups.

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Note for the use of longitudinal reinforcement:

The material, specification and type of welding rod of the steel bar should conform to the design and construction specifications of the steel bar project, and there is a material and product qualification certificate and physical property inspection.

The specifications, shape, size, quantity, spacing, anchorage length, joint position, and thickness of the protective layer of the steel bars must meet the design requirements and the provisions of the construction specifications. Welders must hold the corresponding level of welder certificate.

Only then is it allowed to be operated.

To put it simply, the bottom rib is not truncated. Make lap joints on the bearings.

The gluten is truncated at 1 3 of the beam clear span.

From the perspective of force, it is advisable to truncate at the reverse bending point (that is, where the bending moment is 0). Generally, it is 1 3 of the net span, so it is agreed to be truncated at 1 3. 11G101 is also described, so see the 11G101 Atlas for details.

The upper reinforcement of the beam is truncated at 1 3 places away from the net span of the beam support, because the shear force near the support is large, and is used to resist the shear force;

The lower part of the beam reinforcement is lapped at the distance beam support, and can not be disconnected, because the bending moment in the span is beaten, and the bending moment near the support is small;

The lap range of the upper reinforcement of the beam is the 1 3 range in the beam, and the lower reinforcement is the 1 4 range of the beam end.

The truncation indicates that it is not clear, and in the case of seismic allowability, in order to avoid the reinforcement at the node being too dense, there is a beam bottom reinforcement that is truncated at the support. But it's rare, and I'm not clear about this either.

Maximum limit value of tensile and shear resistance.

Summary. The truncation of the negative bending bar of the main beam is determined by the length of the negative moment area, and the length of the steel bar should be able to cover the length of the negative moment area. Thus it can be pulled. Second, the steel bar should meet the anchorage length, and the length required for anchorage should be met after truncation.

Dear Hello Glad to serve you The truncation of the negative bending rib of the main beam is determined according to the length of the negative moment zone.

The truncation of the negative bending bar of the main beam is determined by the length of the negative moment area, and the length of the steel bar should be able to cover the length of the negative moment area. Thus it can be pulled. Second, the steel bar should meet the anchorage length, and the length required for anchorage should be met after truncation.

The negative bending bar of the main beam is a steel bar set up to resist the negative bending moment in the reinforced concrete components of the construction project, which is often referred to as "negative bending bar" in engineering, and is generally used in two parts: beam support bar and plate negative bending bar; Among them, the support rib is commonly called"Flat tendons"、"Pressing beam iron"；Plate negative reinforcement is also commonly known as "buckle reinforcement" or "cover reinforcement".

The bending position of the longitudinal reinforcement in the beam, determined according to the shear force, is generally greater than or equal to, and ho is the beam height.

The longitudinal reinforcement mainly plays a role in resisting the shear resistance of the longitudinal part, and also plays a connecting role. When it is bent, its ability to be in the longitudinal direction cannot be lost. When it is truncated, its integrity is lost, and it can be connected with stirrups and tied with wires.

Starting from the support, the first gluten is 50mm away from the side of the support at the downward bending point, and 50mm (to the middle of the span) is added to the point projected by the lower part of the beam at the angle required by the drawing.

In industrial and civil construction, it is forbidden to cut off the bending steel bar in the middle of the span, because it is also a tensile bottom bar that resists the positive bending moment. When there are many longitudinal bars in the beam, the bent reinforcement should be relinquished to the second or even third row (upper or lower); Bending reinforcement should not be arranged as corner bars.

Some of the internal reinforcements of the beam can be disconnected, which does not affect the bearing capacity of the structure.

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Some of the internal reinforcements of the beam can be disconnected, and do not affect the bearing capacity of the structure is that the upper reinforcement of the frame beam can be broken, but there are two can not be opened, and the pin should be connected together, and these two are long ribs, which are earthquake resistant.

The straight liquid bend diameter is not less than 14 in the first and second stages, and not less than 12 in the third and fourth stages, and must be reliably anchored at the beam end. The specification does not stipulate that it must be a corner bar, but it should be placed symmetrically. Frame beam (kl) refers to a beam connected to a frame column (kz) at both ends, or a beam connected to a shear wall at both ends but with a span-to-height ratio of not less than 5.

Now in structural design, there is another point of view for frame beams, that is, beams that need to participate in seismic resistance. Pure frame structures are becoming less and less common with the rise of high-rise buildings, and the frame beams in shear wall structures are mainly beams that participate in seismic resistance.

The first row of steel bars in the upper part of the beam is truncated, and the rise of the old liquid is ().

Correct answer: ln 3

In practical engineering applications, in the positive moment section, if the positive reinforcement needs to be truncated, how to stipulate?

The operation requirements of the steel bar cutting machine are: 1. The working surface of the material should be kept level with the lower part of the cutter, and the length of the workbench can be determined according to the length of the processed material. 2. Before starting, check and confirm that there are no cracks in the cutter, the bolts of the knife holder are tightened, and the protective cover is firm.

Then after patting the queen Bo Ming rotated the pulley by hand, checked the gear meshing clearance, and adjusted the cutter clearance. 3. After starting, the base should be empty and the transmission parts and bearings should be checked before they can be operated.

a) Correct. b) Errors.

The truncated position of the longitudinal reinforcement should be at the "theoretical breakpoint."

a) Correct. b) Errors.

Frame structure. The wall of the house can be dismantled at will, and the beam can be removed without registering, which will affect the power transmission of the floor.

The second row of the upper part of the beam is truncated and the long annihilation cover is ().

Stuffy with 2 Correct Answer: ln 4