In order for a multi-storey building to meet all the requirements of strength, it is necessary to use high-quality materials. To date, the construction industry is replete with floors of various types, but most often resort to the installation of ribbed floor slabs. Such a high popularity of this type of load-bearing structures is understandable, because they have the ability to evenly cope with the load transmitted from a heavy building.
Technical parameters and description of the plates
Ribbed flooring is available in the form of a solid plate with an auxiliary longitudinal element that performs the function of a beam that works in bending. If it is necessary to minimize the effect of a very high load, resort to transverse ribs. It is interesting that the concrete leaves the tensile area and is localized in the places of compression, and that is why the supporting element redirects the load most correctly. To save cement material and reduce plate thickness, the ribbed element is reinforced, while its strength properties remain at the required level.
Most often, these ceilings are installed in industrial facilities and attics of impressive complexes. The main condition put forward during installation work is compliance with the step of the load-bearing wall, which can reach a maximum of 6 m. Such elements are not used in the housing stock due to the fact that there is insufficient bottom surface for cladding. Specialists calculate the design in a special program that decrypts the composed schemes. On an industrial scale, slabs are made from different types of concrete:
- lung;
- heavy;
- silicate.
Based on this information, we can distinguish the following parts with tensile reinforcement:
- top plate with a flat configuration;
- special shell materials with a vaulted surface.
Marking
Product labeling contains the following components:
- Alphabetic and numeric characters that decode parameters (dimensions, weight).
- Bearing coefficient.
- Armature characteristics (class, type).
- Brand and type of concrete.
- Additional properties (if any).
As an example, we decode the following information on the products: 2P1–3, At - VI P-1.
The first three characters tell us about the panel size (2P1). The number 3 indicates the separation of the elements of the overlap according to the bearing capacity. Then the class of reinforcement (pre-stressed) is deciphered. The symbol P indicates the use of lightweight concrete, and the symbol T indicates a heavy type. The last digital symbol decodes the design features of the product:
- 1 - additional mortgages are integrated into the plates;
- 2 - side ribs contain technological holes of 210 mm;
- 3 - the same holes, but 210 and 700 mm.
The installation of ribbed ceilings can be carried out using different technologies and it doesn’t matter which method is used - you won’t be able to do without a crane or a tower crane. To properly hook the plate onto the hook, they ensure the presence of specially designed mounting loops, which must be checked before installation for integrity and reliability, as well as their required number is taken into account. When installing load-bearing elements on their seats, you must not step back from the installation technology for a single step.
Standard sizes
U-shaped floor slabs are measured in three dimensions:
- Length.
- Thickness.
- Height.
According to accepted industrial standards, the height of the plates is 22 cm. In rare cases, structures with a smaller thickness (16 cm) are made by special order in factories. The difference between these two samples is the level of noise insulation and the diameter of the technological holes.
The standard length value ranges from 2 to 12 m. At the time of construction design, in most cases they plan to use ceilings, the length of which is from 3.6 to 7.2 m inclusive. If for some reason it is not possible to meet the specified parameters, whether they are less or more, you will have to pay extra for a special order for a consignment. In this case, the dimensions will be changed by the manufacturer.
The width of the ribbed structures according to the standards is 1 m, 1.2 m, 1.5 m, 1.8 m. Square plates (width equal to length) are rare and cost an order of magnitude more expensive than standard ones. Structural elements with a meter width are often added to technical design documentation.
If you are guided by GOST, then you can note the following standard plate sizes (m):
- 3x12;
- 3x6;
- 3x18;
- 1.5x6.
Since the material can have completely different dimensions, it is quite natural that they have different loads. Given this factor, in construction usually use panels with a weight of 770 to 820 kg / m². If a large load is provided, then the plates need to be purchased heavy (2500 kg / m²).
Load calculation
Before you purchase ribbed panels, you need to carry out a number of important calculations. Such calculations will help determine exactly what load the plate can handle. Only after this, according to the obtained values, it is possible to purchase a building material, the technical characteristics of which correspond to the requirements of the construction of an object.
If we talk about the load, then it can be different:
- constant;
- temporal;
- uniform;
- uneven.
The calculations include an exceptionally uniform load, since it is most common at construction sites. The unit of measurement for this value is kg / m².
Requirements
The following requirements are imposed on finished products:
- dimensions must comply with GOST for ribbed panels;
- mandatory compliance with the standards of strength, rigidity and resistance to cracking, frost resistance (established by the test);
- embedded and mounting loops should be made of steel of a standard and a certain diameter. Metal elements are treated with anti-corrosive compounds, and casting molds comply with approved standards.
There are also requirements for concrete, namely:
- lightweight concrete has a density of 1m³ / 1800-2000 kg and corresponds to the indicated porosity; for heavy concrete, the density varies within 1m³ / 2200-2500 kg;
- Reinforcement tensioning is carried out after concrete reaches the control strength, the value of which is indicated in the design;
- The quality of all concrete components must comply with GOST.
- in the case of the use of stoves in areas with an aggressive gas environment, the production of ceilings is regulated by the design documentation for the construction site.
The quality of fittings and hinges is regulated as follows:
- for ribbed plates, reinforcement made of permitted steels can be used, which is indicated in the design documentation;
- the shape and dimensions of the hinges and embeddeds must correspond to the drawings, state standard specifications and operational characteristics;
- reinforcement tension is performed mechanically or electromechanically;
- the stress factor in the reinforcement after tension can deviate from the maximum allowed in the project by 10%.
All these technical data and standards indicating the typical sizes of the floors will allow the correct selection of p-shaped panels that will reliably fulfill the mission assigned to them.