High-rise buildings are complex structures that must meet all the requirements of strength and safety. One of the most significant elements in construction are floor slabs. There are several types of parts. U-shaped floor slabs are very popular, which are distinguished by a high ability to evenly distribute the load transmitted by a heavy structure. Consider the features and types of these supporting structures.
Description
Ribbed types of overlap are available in the form of a solid plate equipped with an additional longitudinal element. It serves as a bending beam. If necessary, minimize the effects of excessive load using transverse ribs. It is worth noting that the concrete in the U-shaped floor slabs passes from the tensile area to the compression places, where it is concentrated as much as possible. This leads to the extremely correct redistribution of the load. In order to save mortar and reduce the thickness of the product, ribbed inserts are reinforced without loss of strength characteristics. Depending on the subsequent application, the plates can be equipped with additional stiffening ribs or technological holes.
Features
Mostly, U-shaped floor slabs are mounted on industrial facilities and on the upper floors of large-scale built complexes. A prerequisite for installation work is strict adherence to the step of the walls of the bearing type, the maximum value of which should not exceed 6 meters.
Such structures are not used for the construction of residential premises, since there is an insufficient supply of the lower part for cladding. Structural analysis is carried out by specialists using a special program that decrypts the resulting schemes. For the manufacture of U-shaped floor slabs, various types of concrete are used: light, heavy and silicate grades. End products with tensile reinforcement can be divided into two groups: top plates with a flat shape and special configurations such as shells with a vaulted surface.
Labeling Explanation
The marking of the product in question includes alphanumeric designations indicating certain characteristics (dimensions, weight). Also, by marking, you can find out the following information:
- Carrier endurance coefficient.
- Type and category of fittings.
- Brand and grade of concrete.
- Additional options (if any).
The first three characters in the code indicate the typical dimensions of the plate (for example, 2P1). The next figure characterizes the separation of elements by bearing capacity. The following is a description of the reinforcement (for example, At - VI - a prestressed element). Then indicate the type of concrete (P - light brand, T - heavy type). The last figure indicates the design features of the design:
1 - U-shaped floor slabs are equipped with additional mortgages.
2 - on the side ribs there are technological holes with a diameter of 210 mm.
3 - a similar configuration, but with holes of 210 and 270 mm.
Mounting
Ribbed panels can be installed using various technological processes. In any case, an automobile or tower crane will be required to carry out the work. To engage and move the plates, they are equipped with mounting loops, which without fail pass a control check for the integrity and reliability of fixation. During the installation of load-bearing elements on the seats, it is necessary to strictly observe the installation technology.
U-shaped floor slabs: dimensions
The considered supporting materials are usually measured in three positions: along the length, thickness and height. Accepted production standards provide for a plate thickness of 220 mm. Modifications with a parameter of 160 mm can be made to order. These options differ among themselves by the level of noise insulation and the diameter of the technological holes.
The length of the panels ranges from 2 to 12 meters. Design dimensions for floor planning are from 3.6 to 7.2 meters. If it is not possible to comply with these sizes, the dimensions are changed by the manufacturer for a fee.
Standard widths are 1 / 1.2 / 1.5 / 1.8 meters. In exceptional cases, square panels (2 * 2 m) are used. The most popular in construction are products with a meter wide.
According to GOST, several standard sizes of plates of the type in question are provided:
- 3000 * 1200 mm.
- 3000 * 6000 mm.
- 3000 * 18000 mm.
- 1500 * 6000 mm.
Since the panels have different overall dimensions, their load is different. With this in mind, in construction, U-shaped floor slabs are used, the weight of which ranges from 770 to 820 kg / sq. m. Under heavy loads, the estimated mass is 2500 kg / sq. m. Below is a table indicating the types of panels and other parameters.
Load
Before acquiring ribbed load-bearing structures, a number of important and mandatory calculations should be carried out. They will help to accurately determine the maximum load on the plate. Having received the required values, you can proceed to the selection of the appropriate panels. By type, the load is divided into permanent, temporary, uniform and uneven. The calculations take into account only a uniform load, since it prevails at construction sites. This indicator is measured in kilograms per square meter.
Requirements
To the U-shaped floor slabs, the characteristics of which are given above, certain requirements are imposed, namely:
- Overall dimensions of products must comply with GOST.
- The material passes a control test for strength, stiffness, frost resistance, cracking.
- Embedded elements and mounting loops are made to a certain size from a suitable steel grade.
- Metal elements must undergo anti-corrosion treatment, and casting molds must comply with approved standards.
Concrete quality
In the manufacture of slabs U-shaped 6x 1.5 and other sizes, take into account the requirements for concrete:
- Light brands have a density of 1 cc. m / 1800-2000 kg, correspond to the indicated porosity. Heavy concrete have this indicator within 1 cubic meter. m / 2200-2500 kg.
- The weakening of the reinforcement tension is performed after the concrete reaches the control design strength.
- All components of the solution must comply with GOST.
If the plates are mounted on sites with an aggressive gas environment, the manufacture of ceilings is regulated by the design documentation for the construction site.
Reinforcement quality
The requirements for fittings and hinges are also regulated in a certain way:
- For the considered floor slabs, reinforcement made of permitted steel grades can be used, which should be indicated in the design documentation.
- The configuration and dimensions of the loops must be selected taking into account operational features, GOST and drawings.
- Reinforcement tension is made mechanically or electromechanically.
- The voltage index in the reinforcement after the tension procedure should not exceed design calculations by more than 10 percent.
Useful Tips
Cement should be applied with a layer of not more than 20 mm immediately before lifting the panel.
Raise the structure using special mechanisms on hooks of the "spider" type. At the installation site, workers adjust the load and direct it to the desired location.
Designs are stacked alternately, the distance between them should be within 5-7 cm.
To create a monolithic overlap, all slots are filled with a solution.
If it is necessary to obtain technical holes of larger diameter, use drilling tools.
Since the weight of the U-shaped floor slab 6x 1.5 is more than 1.4 tons, it is necessary to store the material on a flat platform, shifting each element with wooden blocks. This will avoid deformation of the panel and preserve its characteristic properties.