Horse stool is shaped like a stool, so it is commonly known as horse stool, also known as support. Used to fix the upper floor reinforcement between the upper and lower floor reinforcement. When the foundation thickness is large (above 800mm), it is not suitable to use horse stool, and the bracket is more stable and firm. In general, the reinforcement of horse stool will not be indicated on the drawing. Only a few designers design horse stools, most of which are specified in detail by project engineers in construction organization design. Usually, the specification of horse stool is one level smaller than that of plate reinforcement. Such as plate steel bar diameter Ф12, can be used as a horse stool with diameter Ф10, or the same as plate steel bar. The vertical and horizontal spacing is generally 1 m. However, specific problems have to be treated in detail. If the reinforcement of double-layer two-way slab is Ф 8 and the rigidity of reinforcement is low, it is necessary to reduce the spacing between horse and stool, for example, the spacing is @800*800; if the reinforcement of double-layer two-way slab is Ф 6, the spacing between horse and stool is @500*500. Some flat plates have larger specifications. If the diameter is Ф14, the spacing between horse and stool can be appropriately increased. In a word, the setting principle of horse stool is to fix the upper steel mesh firmly, which can withstand all kinds of construction activities and ensure that the protective layer of the upper steel is within the scope specified in the specification. When the thickness of the plate is very small, there is no need to configure a horse stool. For example, if the height of the horse stool is less than 100MM and less than 50mm, it can't be processed, and short steel bars or other materials can be used instead. In a word, the setting of horse stool should conform to the principle of moderate use, which can not only meet the requirements but also save resources.
Quota regulations on horse stools
In some places, the quota clearly stipulates the calculation of reinforcement of horse stool, so it should be calculated according to the quota rules. However, this calculation result can only be used for budget and settlement, not for construction blanking, because it is only a weight, not from its own function and stress characteristics. For example, if there is no provision in Zhejiang quota, the material of horse stool should be reduced by one specification compared with the reinforcement of floor slab, and the length should be calculated at 0.2 m twice the thickness of floor slab, so as to calculate the total reinforcement. The quota of Shanxi Province is calculated by 1 root /m2, and the diameter is calculated by φ 12. Obviously not applicable to architecture.
How to calculate the number of horse stool tendons?
The number of horse stool reinforcement can be calculated according to the area, and the number of horse stool reinforcement = plate area/transverse spacing of horse stool reinforcement * longitudinal spacing. If the plate reinforcement is designed in the form of bottom reinforcement and load-bearing negative reinforcement, and there is no temperature reinforcement, then the number of horse stools must be deducted from the hollow part. The beam can reinforce the horse stool, so the number of horse stools must be deducted. Elevator shaft, stairwell and floor hole are not calculated without horse stool, and stair horse stool is calculated separately.
How to calculate the reinforcement length of horse stool?
Height of horse stool = thickness of plate -2* protective layer-σ (sum of diameters of upper plate reinforcement and bottom plate reinforcement).
On the straight pipe section, the plate spacing is +50 mm (it can also be 80mm, and an upper steel bar is placed on the horse stool), while on the left lower straight pipe section, the plate spacing is +50 mm, and on the right lower straight pipe section, it is 100, so that two steel bars can be placed on the upper part of the horse stool, and the lower three points can be smoothly supported on the lower steel bar of the plate. The reinforcement of the horse stool can't touch the formwork to prevent the reinforcement of the horse stool from rusting.
Specification of reinforcement for horse stool:
When the plate thickness is less than or equal to140 mm, and the plate stress reinforcement and distribution reinforcement are less than or equal to10, the diameter of the saddle reinforcement can be Ф 8; When140mm
Measuring reinforcement in raft foundation
In large raft foundation, the reinforcement is not necessarily the reinforcement of horse stool, but often the steel corbel. It is necessary to calculate the support and determine its specifications and spacing to ensure its stability and bearing capacity. When determining the support load, besides the upper reinforcement load, the construction load should also be considered. The spacing between supporting columns is generally 1500MM, and only one long angle iron is needed on the column, which should be perpendicular to the bottom skin reinforcement of the upper reinforcement, and the spacing is generally 2000m. In addition, diagonal braces should be welded. The design of the support should have a calculation formula, and construction can only be carried out after approval. This is not just based on experience. Too small support specifications and spacing will cause waste, and too large support specifications and spacing may cause serious consequences of the overall collapse of foundation reinforcement. Therefore, the stent design cannot be taken lightly.
Other precautions for horse stool
Construction projects generally have special horse stool reinforcement construction organization design. If there is no clear and detailed description of the horse stool in the construction organization design, it will be calculated as usual, but there are two preconditions, that is, the horse stool should have a certain rigidity, which can withstand the trampling of the construction personnel and avoid the distortion and sinking of the upper plate reinforcement. Second, in order to avoid solving disputes and wrangling in the future, the horse stool needs to go through the necessary formalities and visas, which are put forward by the construction unit in the form of engineering contact list according to the actual production situation, submitted to the supervision and construction unit for confirmation, and calculated according to the confirmed size.
According to clause 19 on page P52 of the bill of quantities valuation specification, the supporting steel bars and double-layer steel bars at fixed positions in cast-in-place members are "iron horses", and the anchoring steel bars of protruding members and the hooks of prefabricated members are incorporated into the steel bar quantities. Why do steel bars that look like measurements in physical engineering count? Very simple, because it is hidden in concrete, forming an engineering entity. Therefore, although the horse stool is a measure reinforcement, it should be classified as a solid project rather than a measure project. When compiling the bill of quantities, the bidder shall calculate the quantity of the horse stool combined with the steel bar, and describe it clearly in the engineering characteristics and work contents. Bidders need to calculate the number of horse stools when reviewing the bill of quantities, which should be considered in the comprehensive unit price and not included in the measure fee.
The reinforcement of horse stool in Shanghai is included in the total reinforcement according to the actual calculation, and it is wrong for some construction units to set the horse stool as embedded iron parts.
The arrangement of horse stools can be rectangular or plum blossom-shaped, generally rectangular. The direction of the horse stool should be consistent.