You should understand these things about horse stools

The horse stool bar, its main function is to support between the upper and lower skin steel bars of the board, to ensure the distance between the two skin steel bars In line with the requirements of the specification, the steel bar is used as a horse stool, and the vertical and horizontal spacing is about 600-1000 to support it.

The concept of horse stool

As the measure reinforcement of the slab, the horse stool bar is indispensable, and sometimes it is very important from the technical and economical point of view. It is not only the category of design, but also the category of construction and budget. Some people who lack practical experience and perceptual knowledge tend to ignore and omit calculations. The horse stool is not a simple concept, but there is no specific theoretical basis and data, no general calculation standards and norms, and it is often based on experience and intuition. But if you understand the reasoning and understand the actual construction, then it is not difficult to calculate the horse stool tendons. Anything that complicates the simple and simplifies the complex is harmful.

Horse stool, it is shaped like a stool, so it is commonly known as a horse stool, also known as a brace. It is used between the steel bars of the upper and lower slabs, and plays the role of fixing the steel bars of the upper slab. When the thickness of the foundation is large (greater than 800mm), it is not suitable to use a horse stool, but to use a bracket to be more stable and firm. Horse stool steel bars are generally not noted on the drawings. Only individual designers design horse stools. Most of them are marked in detail by the project engineer in the construction organization design. The specifications, length and spacing are usually one level smaller than the specifications of the horse stool, such as A steel bar with a diameter of ф12 can be used as a horse stool with a diameter of ф10, and of course it can be the same as the steel bar. The vertical and horizontal spacing is generally 1 meter. However, the specific problem has to be treated in detail. If the double-layer two-way reinforcement is ф8, the steel bar rigidity is low, and the distance between the horse stools needs to be reduced. For example, the distance is @800*800. If the double-layer two-way reinforcement is The distance between ф6 horse stools is @500*500. Some slab steel bars have larger specifications. If the diameter ф14 is used, the distance between the horse stools can be enlarged appropriately. In short, the principle of setting up the horse stool is to fix the upper steel mesh firmly, be able to bear various construction active loads, and ensure that the protective layer of the upper steel bars is within the scope specified in the code. When the plate thickness is very small, it is not necessary to configure the horse stool. If the height of the plate horse stool less than 100MM is less than 50mm, it cannot be processed. It can be replaced by short steel bar head or other materials. All in all, the setting of the horse stool should conform to the principle of sufficient and moderate, which can meet the requirements and save resources.

Regulations on quotas for horse stools

In some places, the quota has clear regulations on the calculation of horse stool bars, so it is calculated according to the quota rules, but this calculation result can only be used for budget and settlement and cannot be used for construction blanking, because it is only a weight, and It is not calculated from its own function and force characteristics. For example, the Zhejiang quota stipulates that when there is no regulation in the design, the material of the horse stool should be lower than the bottom plate steel bar by one specification, and the length is calculated as twice the bottom plate thickness plus 0.2 meters, 1 per square meter , to calculate the total amount of reinforcement. Shanxi Province's quota regulations are calculated according to 1 root/m2, and the diameter is calculated according to Φ12, which is obviously not suitable for construction. How to calculate the number of horse stool tendons? The number of bars can be calculated according to the area. The number of horse stool bars = plate area / horizontal distance of horse stool bars * longitudinal space. Hollow parts must be deducted. The beam can act as the tendon of the horse stool, so the number of horse stools must be deducted from the beam . Elevator shafts, stairwells and board holes that do not require horse stools shall not be counted, and stair horse stools shall be calculated separately.

How to calculate the length of the horse's stool?

Stool height = plate thickness - 2 * protective layer - Σ (the sum of the diameter of the upper bar and the bottom row of the plate). The upper straight section is the rib spacing + 50 mm (or 80mm, and an upper steel bar is placed on the horse stool), the lower left straight section is the rib spacing + 50 mm, and the lower right straight section is 100, so that the horse Two steel bars can be placed on the top of the stool, and the bottom three points are stably supported on the lower steel bars of the board. The horse stool bars cannot touch the formwork to prevent the horse stool bars from rusting. Specifications of horse stool bars: When the thickness of the plate is ≤140mm, and the stress and distribution bars of the plate are ≤10, the diameter of the horse stool bars can be ф8; when 140mm<h≤< span>

200MM, when the plate stress rib<=12, the diameter of the horse stool reinforcement can be ф10; when 200mm

Measurement reinforcement in raft foundation

In the large-scale raft foundation, the steel bars are not necessarily horse stool steel bars, but steel brackets. The brackets must be calculated to determine their specifications and spacing, so as to ensure the stability and bearing capacity of the brackets. When determining the load of the bracket, the construction load is considered in addition to the calculation of the upper reinforcement load. The spacing between the columns of the support is generally 1500MM, and only one direction of full-length angle irons needs to be set on the columns. This direction should be perpendicular to the bottom steel bar of the upper steel bar, and the spacing is generally 2000 meters. In addition to welding with diagonal braces. The design of the bracket should have a calculation formula, and the construction can only be carried out after approval. It cannot be based on experience alone. If the bracket specification and spacing are too small, it will cause waste. If the bracket specification and spacing are too large, it may cause serious consequences for the overall collapse of the foundation reinforcement. So bracket design cannot be taken lightly. Other considerations for horse stool

Construction projects generally have a special construction organization design for the horse stool reinforcement. If there is no clear and detailed description of the horse stool in the construction organization design, then it will be calculated according to the routine, but there are two prerequisites, that is, the horse stool The stool must have a certain degree of rigidity, which can withstand the trampling of the construction personnel, and avoid twisting and sinking of the steel bars on the upper part of the board. The second is to avoid settlement disputes and wrangling in the future, to handle the necessary procedures and visas for the horse stool, and the construction unit will propose it in the form of a project contact sheet according to the actual production situation, and report it to the supervisor and construction unit for confirmation, and calculate according to the confirmed size.

According to Article 19 on page P52 of the bill of range pricing specification: the supporting steel bars in the fixed position of the cast-in-place components, the "iron horse" for the double-layer steel bars, the anchoring steel bars of the protruding components, the hooks of the prefabricated components, etc. Incorporated into the steel engineering quantity. Why is the steel bar that seems to be used for measures counted in the physical project? It is very simple, because it is hidden in the concrete to form an engineering entity. Therefore, although the horse stool is a structural steel bar, it should be classified as a physical item rather than a functional item. When compiling the bill of quantities, the bidding unit shall calculate the amount of horse stools combined in the steel bars and describe clearly in the project characteristics and work content. The bidder needs to calculate the engineering quantity of the horse stool when reviewing the bill of quantities, and consider it in the comprehensive unit price, not in the measure fee.

Some things about horse stool

Reinforcement is included in the total amount of reinforcement according to the actual calculation and participates in the adjustment of reinforcement. It is wrong for some construction units to use horse stools as pre-embedded iron parts.

The arrangement of horse stools can be arranged in rectangles or in plum blossoms, generally in rectangles. The direction of the horse stool should be consistent. In order to save steel bars, some irregular construction units use other hard objects such as stones, pads, wood blocks, plastics, etc. to act as horse stools instead of using horse stools to fix steel bars. This is unprofessional barbaric construction.

In general, the horse stool bars are input in the steel bar graphics software, which is very convenient and quick to calculate the weight of the horse stool.

It is best to go to the site with the supervisor to confirm and apply for a visa before pouring, especially for the special structures such as rafts and sumps, and the specifications and shapes of the horse stools are also relatively special. Once the concrete is poured, no one can Not knowing what it's like inside, without written information is dangerous.

I don’t know where the so-called regulation that the bar of the horse stool is one specification lower than the bar of the board is set, I let it hurt once, it’s too unreasonable. At a certain construction site, Party A delayed signing the visa for the horse stool reinforcement. When the calculation was made, the audit said that the steel reinforcement was 8, and the horse stool reinforcement had to be counted as 6 for me. I said you want to use six steel bars to make it. Can the horse stool withstand construction loads? After stepping on the gluten and the horse stool, they both fell down together, but the audit will accept the written materials, and if there is no material, it will follow the regulations. It is really angry to vomit blood. Fortunately, it was reported to Party A later that the visa attachment was concealed. Otherwise, the number of tens of tons of 12 steel bars in the horse stool is calculated as 6. How much is the loss!

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