RU166749U1 - ELEMENT OF MONOLITHIC CONCRETE COVERING - Google Patents

Abstract

An element of a monolithic concrete floor containing a base with a reinforcing cage installed and fixed in it, the base being a U-shaped thin-walled steel profile with shelves made on the outside of the profile walls, characterized in that perforation is made on the inner surface of the walls protrusions are made on the bottom of the profile, the longitudinal axes of which are oriented at an angle from 30 ° to 90 ° to the longitudinal axis of the profile.

Description

The utility model relates to the field of construction and can be used in the construction of prefabricated-monolithic, mainly often ribbed ceilings.

The fixed formwork of often-ribbed precast-monolithic concrete floors most often includes two main elements: beams in which the reinforcing frame of the floor is placed and fixed, and blocks that fill the space between the beams.

Beams and blocks are load-bearing elements of the formwork and absorb the loads arising from concreting and hardening of concrete.

The floor formwork beam is a monolithic (concrete, metal, composite, etc.) or hollow (metal, ceramic, etc.) base with a reinforcing cage installed in it, consisting, as a rule, of longitudinal and transverse, including diagonal reinforcement . The manufacture of beams with a monolithic base is carried out, most often, in the factory. The manufacture of hollow base beams can be carried out both in the factory and directly at the construction site.

As a rule, the metal (steel) base of the beam has a sufficiently high tensile strength. In order to ensure high strength of the floor as a whole, it is necessary to ensure sufficient adhesion of the concrete core of the beam to the metal base, in this case, the base of the floor beams will function similarly to the external (sheet) reinforcement in steel-concrete floor structures. This allows you to increase the bearing capacity of the floor or reduce the degree of reinforcement of the floor with reinforcement.

Known sheet reinforcement of reinforced concrete structures in accordance with the patent for the invention No. 1557289 (publ. 04/15/1990 IPC E04C 5/03), which can be used as a fixed formwork, which allows to increase the bearing capacity of reinforced structures. The reinforcement is a corrugated metal sheet with a rectangular or trapezoidal shape of the corrugations, on the side walls of which protrusions are stamped located in the direction of the zigzag broken line with the same bending angles and a height of at least half the height of the walls. The protrusions can be made intermittent at the inflection points of the broken line. The protrusions increase the adhesion of sheet reinforcement to concrete. As a result, the bearing capacity of reinforced structures increases.

A steel-concrete beam is known in accordance with Utility Model Patent No. 152451 (publ. 05/27/2015, IPC Е04В 1/20), containing a base in the form of an integral or composite I-beam profile, in the wall of which anchor elements are stamped in the form of studs. Anchor elements provide improved adhesion of concrete to the steel base, but the beam must be filled with concrete in the factory.

Thus, improving the adhesion of concrete to metal structures whose surfaces are in direct contact with concrete, due to the use of various types of bumps, is known in the art, but its use for precast-monolithic ceilings is unknown since metal substrates for precast-monolithic beams began to be used relatively recently .

Known technical solution set forth in patent No. 133169 (publ. 10.10.2013, IPC E04G 11/36) for the utility model "Element of a monolithic concrete floor". This element of a monolithic overlap contains a base with a reinforcing cage installed in it, and the base is made in the form of a U-shaped profile with shelves on the outer sides of the profile walls. This design of the base allows the installation of blocks of fixed formwork with support on the shelves. The formwork thus assembled is filled with concrete directly at the construction site. The base is a thin-walled bent profile with a smooth, usually galvanized, surface. The smooth inner surface of the profile in contact with concrete does not increase the adhesion of the profile and concrete. This technical solution is selected as the closest analogue.

The technical problem of the claimed utility model is being solved by increasing the strength of a precast-monolithic floor made on the basis of elements with a U-shaped steel base and shelves on the outer sides of the walls.

The technical result of the claimed utility model is to increase the adhesion strength of concrete to the surface of the metal base of the beams.

The specified technical result is achieved due to the fact that in the element of a monolithic concrete floor containing a base with a reinforcing cage installed and fixed in it, the base being a U-shaped thin-walled steel profile with shelves made on the outside of the profile walls on the inner surface of the walls perforation with flanging was made, protrusions were made on the bottom of the profile, the longitudinal axes of which are oriented at an angle from 30 ° to 90 ° to the longitudinal axis of the profile.

Under normal operating loads, the impact on a precast-monolithic overlap is transverse bending loads. At the same time, shear forces act in the contact zone of the concrete surface and the metal base. The presence on the walls of the profile of flanges on the perforation and protrusions on the bottom of the base allow partial transfer of tensile forces to the base, under the action of which there is a concrete core in the base zone. A significant number of flanges on the walls of the base and protrusions on the bottom of the base contributes to a more even distribution of tangential shear forces over the entire cross section of the base, increasing the efficiency of using its strength characteristics. By the nature of the interaction with the concrete base, flanging on the perforations and protrusions on the bottom of the base perform functions similar to the transverse ribs of the periodic profile of reinforcing bars.

In accordance with the studies for steel concrete floors (http://www.stako.ru/news/61/), the presence of protrusions on the side walls of the corrugated sheet increases the adhesion strength of the latter to the base concrete by 2-5 times. Similar indicators can be achieved for precast monolithic floors.

The shape of the holes during perforation can be diverse (round, square, diamond-shaped) and has little effect on the adhesion strength of the base with concrete. The total area of the perforation holes should not exceed half the area of the profile wall. A large area leads to a weakening of the wall and the possibility of crushing it when loading the floor.

Under the flanging of the perforation in this application refers to the bending of the edge of the holes of the perforation into the base without a gap or with a gap in the metal. The flanging height is not less than one, but not more than five mm. The angle of inclination of the flanging walls with respect to the plane of the base wall is from 30 to 60 degrees. Smaller angles do not provide the necessary height of the flanging walls, large angles increase the area of metal fracture in the upper part of the flanging, which can lead to excessive leakage of liquid components of the concrete mixture. The cross-sectional shape of the protrusions has little effect on the adhesion of the base to concrete and is determined mainly by the ductility of the metal and the technological capabilities of roll forming equipment. The height of the protrusions should ensure the integrity of the metal during their formation. Depending on the ductility of the metal used to make the base, the height of the protrusions can vary from one to five mm. A smaller height of the protrusions does not provide the necessary adhesion strength of the base with concrete, a large leads, as a rule, to rupture of the metal. Ultimate (excessive off-design) loading of the floor leads, as a rule, to the crushing of the protrusions by the concrete core of the beam. The collapse force of a particular protrusion is determined by a combination of several factors: the strength and thickness of the base metal, the area of the protrusion, its height and the angle between the longitudinal axis of the protrusion and the direction of action of the crushing forces. The calculations show that the selected angles (90-30 degrees) provide maximum strength indicators of adhesion of the base to concrete.

The essence of the claimed technical solution is illustrated by the following figures:

FIG. 1 - Isometric image of the metal base of the slab formwork (profile) with perforation on the inner surface of the profile walls and protrusions on the bottom of the base.

FIG. 2 - Possible options for the execution of the shape of the holes during perforation and configuration flanging:

2A - round, 2B - rectangular, 2B - diamond-shaped.

FIG. 3 - Beam of fixed formwork with the declared base profile.

FIG. 4 - A possible embodiment of the protrusions on the bottom of the profile.

The claimed element of fixed formwork of prefabricated monolithic overlap contains the base 1 of the beam with a U-shaped cross section made of thin-walled metal, and perforation 2 with flanging 3 is made on the inner surfaces of the walls of the profile, which increases the adhesion of the profile to concrete. On the bottom of the base 1, protrusions 4 are made.

The perforation of the walls and the formation of the protrusions is carried out simultaneously with the manufacture of the profile on roll forming equipment.

Claims (1)

An element of a monolithic concrete floor containing a base with a reinforcing cage installed and fixed in it, the base being a U-shaped thin-walled steel profile with shelves made on the outside of the profile walls, characterized in that perforation is made on the inner surface of the walls protrusions are made on the bottom of the profile, the longitudinal axes of which are oriented at an angle from 30 ° to 90 ° to the longitudinal axis of the profile.

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