Reinforced concrete runs. Use of reinforced concrete purlin beams Dimensions of RC purlins

Any design must be safe. In order for the building to be strong, they mainly use, which are different in their parameters.

Application area

Beams, or reinforced concrete girders, are made from up to M600, tk. this material has maximum resistance to crumbling, fire, frost, water.

Concrete girders are used as a supporting structure for various small buildings, for example, administration buildings, residential buildings, which are built of bricks or blocks of various types.

1. In the form of a base, which is laid under a layer of slabs between floors. This is especially common in those buildings where load-bearing walls do not have good resistance.
2. As reinforcement of the truss system.
3. Like reinforced concrete lintels that are located above wide doorways and windows. This method of application allows you to remove the load on this area.
4. As part of the design in flat roofs when the slope is less than 5%.
5. As an element that connects two parts of one building.
6. To create technological recesses.

There are several types of buildings in which reinforced concrete runs are most often used. These include:

• unheated buildings, the roof lies directly on the concrete girders;
• heated buildings, the roof is laid on insulated slabs;
• heated buildings, where there are small building envelopes.

It is necessary to know in what conditions this building material is used. For example, beams can withstand temperature fluctuations in the street -40 ... + 50ºС. If there is a seismic source in the region, they can withstand fluctuations of no more than 7 points.

When exposed to a gaseous medium, it is freely transferred if it is of a non-aggressive type. But any application is permissible with the correct construction of the structure.

Classification

Since there are many varieties of these structures, it is worth considering in more detail each direction. This will allow you to understand what the beams are.

By section

Reinforced concrete profile may vary in cross section. One view has a rectangular cross section and is a pillar in which a recess is provided. The second type is the tee, which in the section resembles the letter T, has a small shelf on which plates can be installed. The last type of runs include those that have a shelf on one side only and resemble the letter G in a section.

According to the shape of the shelf and the type of reinforcement

Also, products differ in shape and type of reinforcement.

• 1PR means that the shelf can be placed relative to the rib at an angle of 90º, and the reinforcement itself is made of longitudinal rods;
• 2PR means that the shelf is perpendicular to the rib, and the reinforcement is stressed (this feature increases the load-bearing properties of the beam);
• 3PR indicates that the shelf is placed perpendicularly, but the frame is tense, because used to support a roof with a slight slope;
• 4PR indicates that the shelf is at a small angle, the reinforcement is stressed, while the roof has a large slope;
• 5 PR indicates that the shelf is installed at a slight angle, there is a prestressed frame.

Marking

In addition to the above, other types of marking are also used. For example, if a beam has a simple rectangular section, then a combination of the following numbers and letters can be affixed to it - PRG 60.2.5-5AIII.

• PWG is an abbreviation for cross section;
• 60 - dimensions in decimeters, in this case it is indicated that the beam is 6 m long;
• 2 - indicates the width (in dtsm);
• 5 - height (in dcm);
• 5 - indicates the permissible load (in t), in this case 500 kg per 1 linear meter. m.
• AIII is the type of reinforcement used.

T-beams also have their own markings. For example, if 2PR-1 AtIV-N is written on the product, then this means the following:

• 2PR - beam type;
• 1 - serial number, which is responsible for the bearing capacity of this reinforcement;
• АтІV - the class to which the fittings belong;
• H - indicates the property of concrete (resistance to various aggressive influences, impermeability).

The letter P at the end of the marking indicates the permeability of the material.

Technical specifications

For the manufacture of such products, high-quality and heavy concrete is used. This makes it possible to provide this building material with a good load-bearing quality.

All structural properties are selected individually, and not only the length of the reinforcement, but also the features of the reinforcement are taken into account.

For example, concrete marked M200 is used in cases where the length of the beam does not reach 2.5 m. For reinforcement with a length within 3 m, they are most often used.

If a reinforced concrete beam is needed from 3 to 6 m in size, then M300 concrete is used for manufacturing, for a longer structure, a product marked M350 is suitable.

To make a building material, dense concrete is taken, in which the density index can be up to 2500 kg / m³. This makes the weight of the structure heavier by 150 kg. Today, factories produce a large number of such building beams with various parameters.

Mounting Features

During construction, it is difficult to mount a concrete run, because. the weight and length of the reinforcement of the product is large. When installing, it is necessary to use special devices in order to raise the beam to the desired height. For the convenience of lifting the beams mechanically, each product has special strong loops.

Installation is carried out by at least 4 builders, because it is necessary not only to fix the run on the lifting equipment, but also to put the beam in the right place. There are several companies in Moscow that produce various types of girders and have a team that will help carry out the necessary construction work.

A run is a part of the structure of prefabricated reinforced concrete or brick structures, installed in a horizontal position and based on load-bearing beams or trusses. The elements themselves also have impressive strength and are used as a support for floor slabs or decking. There is a separate GOST for reinforced concrete runs, which regulates all the requirements that products must meet.

In the photo - the girders are based on beams and perform a supporting function during the installation of floors and roofing decks

The main features of this type of structures

All purlins manufactured at reinforced concrete products plants must comply with the standards of GOST 26992-86 "Reinforced concrete purlins for coating buildings of industrial and agricultural enterprises." It is this regulatory document that determines what requirements each product must meet, while a number of indicators are regulated:

Important! Do not confuse runs with jumpers. Lintels are used for similar purposes, but they are much smaller, and are not designed for heavy loads and cannot be used in load-bearing systems. Runs are suitable for any purpose: from strengthening openings (especially large ones) to creating additional strength in the places of reinforced concrete slab supports.

Types of runs

The division of products is carried out according to the type of section. There are two main options, each of which we will consider in more detail.

Elements with a rectangular section

From the name it is clear that this type of product has a rectangular shape and is marked with the designation PR. The scope of their use is quite wide, such elements can be found on many structures.

We note the main features of this group of products:

• The use of heavy grades, which allows the use of runs at any industrial facilities.
• There are two main design options: solid and lattice. The second option is lighter due to the presence of voids and is most often used when mounted on trusses, they are located in increments of 6 meters.
• Prestressed reinforcing bars are used to increase strength. In ordinary products, a conventional frame is used.

Do not forget that the dimensions of reinforced concrete girders are written in decimeters, the letter "T" means that heavy concrete was used for manufacturing. If there are additional factors, they are also noted in the labeling. Labeling instructions are the same for all manufacturers, so it is important to know the general rules.

Example. Let's analyze the run option 44.3.5-4T, the marking means that the length of the element is 44 decimeters, the thickness is 3, and the height is 5 Dm, the calculated load is 4 tons per meter, heavy concrete was used in the manufacture.

Tee elements

For this group of products we can say the following:

• The high resistance of the material allows the use of runs with significant temperature differences - from -40 to +50 degrees.
• The design of the shelves can also vary, they can be straight (great for flat roofs and roofs with a slight slope) and oblique (this option is suitable for roofs with a slope of 25 degrees).
• Special holes with a diameter of 50 mm make it possible to simplify loading and installation work. Now you can move the elements not only with cranes, but also with other mechanisms - forklifts, lifts.
• If increased reliability is required, it is necessary to purchase products with prestressed reinforcement, their price is slightly higher, but their strength is also greater.

• In addition, pins can extend from the element for additional welding of the structure to other elements. Their number and location is agreed with the customer in advance.
• Also, for additional strength, additional supporting elements can depart from the run. This option is also made only by special order.

Remember! Whichever option you choose, it is important that it is manufactured in accordance with GOST standards. Since it will be subjected to significant stresses, the quality must be at the highest level.

Conclusion

A run is an indispensable element for strengthening any industrial structure, which is why it is so important to choose the option that is optimal in size and characteristics. The video in this article will highlight the nuances and features in more detail.

Are you interested in reinforced concrete girders?

Reinforced concrete runs are used in the construction of various buildings. We are talking about those buildings, the walls of which are made of bricks or large blocks of local materials. Purlins are an element of the building covering, necessary for the formation of various openings in the wall. These reinforced concrete products are placed horizontally, and reinforced concrete slabs or flooring are placed on them. Reinforced concrete run rests on the supporting structures of the building. The role of key supports can be performed by trusses, beams, etc. This is how sustainability is achieved. Sometimes base plates are specially installed to support the girders. Currently, reinforced concrete runs are an integral part of any construction.

Depending on the shape, brand of concrete, as well as a number of criteria, reinforced concrete runs are divided into groups. The marking of these groups includes an alphanumeric designation. The letter index directly indicates the type of construction, PRG - a run of rectangular section. The first number contains information about the overall dimensions of the product, indicated in decimeters. The second number reflects the bearing capacity of the purlin, which is calculated for uniform load conditions. The bearing capacity is measured in tons per meter, without taking into account the dead weight of the run. The last element of the nomenclature is the type of concrete, which is encrypted with a letter designation. Sometimes a third number is also indicated in the product labeling. This numerical group shows the presence of design features in the run. For example, the number "I" is a variant of the reinforcement of the supporting part of the run.

The building structure acquires reliability and strength due to the use in construction of monolithic joints of concrete with steel reinforcement, laid on bearing elements in a horizontal plane. Floor slabs are laid on top of the reinforced concrete girders, thereby creating a reliable and durable structure.

There are several varieties of this building material that have design features that allow them to be used in various works. PR brand products are manufactured in accordance with the requirements of GOST 26992-86. The run has an I-beam rectangular section and is rarely used in construction. In the production process, heavy concrete is used, which allows the use of material in the construction of industrial facilities.

Reinforced concrete PRG girders can be with lattice and solid sections. Lattice samples are much lighter and are used when mounted on trusses, they are placed in increments of 6 m. Solid analogs are made from a rolled or bent channel having a Z-shaped and C-shaped section.

It is assumed that, in accordance with the technological process, the strength of the product increases with prestressing reinforcement. You can get maximum information about the product by studying in detail the labeling, which consists of digital groups. Thus, data on length, nominal width, height and bearing capacity are provided.

Reinforced concrete rectangular purlins have a developed height, but at the same time they can have thin walls; local stability of such a design is provided with the help of specially created limbs.

With tee section

Products with a tee section are made using heavy concrete. It is suitable for floors of several types of buildings:

• unheated premises with corrugated sheet asbestos-cement roofing;
• heated building with lightweight enclosing structures;
• heated building with a sheet asbestos-cement roof laid on insulated slabs.

Reinforced concrete T-section purlins are perfect for unheated buildings, they can be used in open spaces at a temperature of -40 ° C. A distinctive feature of this product is the possibility of its use in the construction of buildings in a zone of increased seismic activity, such structures are able to withstand tremors with an amplitude of 7 points.

The products are capable of withstanding medium to low exposure to gaseous media and process temperatures of +50°C.

There are several types of such structures, conditionally they are divided into two large groups. Products are made with a stick located perpendicular to the edge of the run. Such structural elements are ideal for buildings with a roof slope of no more than 25%. The group under consideration includes the following types:

• 1PR - longitudinal non-stressing reinforcement is used.
• 2PR - prestressing is applied.
• 3PR - with a prestress for objects with a roof slope of not more than 5%.

It is possible, if necessary, to buy building purlins with slanting flanges, also suitable for objects with a roof slope of 25%. This group includes two types of products, namely 4PR with longitudinal prestressed reinforcement and 5PR with prestressing.

Pricing and labeling

The purlins for industrial roofing of buildings are made of concrete of various types, they can have normal or reduced permeability, which determines their operational characteristics.

Pricing is formed based on several factors. The name of the material, its dimensions and weight are taken into account. A product of small dimensions, for example, PRG 17.1.3-4t with a mass of 0.150 tons, costs 1930 rubles. Medium precast concrete, such as PRG 42.2.5-4t, will cost the buyer 7,500. The largest run PRG 60.2.5-4t is sold for 11,500.

All concrete products have a rectangular section.

An ignorant person will not be able to determine the type of product without understanding the labeling. Prefabricated reinforced concrete girders should be purchased, focusing on the decoding data, as an example, consider the sample PRG 42.2.5-4t:

• 42 - length;
• 2.5 height and width;
• t - heavy concrete.

Length, width and height are given in decimetres.

The offered products are widely popular in the market and are simply indispensable in the construction of administrative, residential, industrial buildings. Professional builders know perfectly well what reinforced concrete girders are and how to use them correctly in the construction of buildings. The main thing is that the purchased concrete products correspond to the operating conditions and are made of high quality materials. Thanks to this approach, the reliability of the structure can be ensured.