The end of the house-building process is crowned by the installation of a roof. This element is fundamental to the safety of the building, and also directly affects the comfort of its operation. As the supporting elements of the roof, rafters and reinforced concrete trusses of 18 m can be used, with the help of which the main and additional weight are redistributed to the walls of the building.

Features of the calculation

Given the importance of the functions performed by trusses and trusses, the process of their calculation, design and installation should be taken as seriously as possible. The smallest inaccuracy can ruin the whole structure ().

The most durable and reliable elements are made of reinforced concrete. However, the complexity of installation in combination with a large total weight limits the use of this type of rafters. They are most often used in unusual cases when, for example, it is necessary to make a one-story building with a large area.

When calculating, not everything is as easy as it might seem at first glance. Therefore, for its implementation is necessary a certain amount of knowledge. In this case, GOST 20213 89 is used for trusses made of reinforced concrete.

Tip: it is very important not to miss a single factor that can have a direct or indirect effect on the final strength properties.

That is why such calculations should be carried out at the design stage by people well acquainted with this area. Every detail is important here - from choosing the rafter design to the choice of small connecting elements.

In the calculations, it is necessary to take into account three factors:

1. The total mass of the structure, which includes the weight of the roofing and the weight of the rafter system.
2. The weight of the loads that may additionally arise during operation (snow, wind, etc.).
3. The weight of periodic loads (various climatic phenomena or random factors).

Extreme accuracy during the calculations will help not only save the overall estimate, but also make the object as protected as possible from all kinds of damage.

The instruction requires the use of high-precision equipment for the manufacture of reinforced concrete trusses, which is able to perform work with minimal errors. When installing rafters, it is especially important to securely fasten all the elements so that the stability of the object is not reduced.

Reinforced concrete trusses

Such structures can vary significantly in appearance, based on their parameters, including the coating material used and the methods of supporting them. With their help, you can erect structures with huge spans (more than 24 m). In addition, the roof can be pitched or slightly steep, and lanterns can be used on the surface of structures.

Tip: use similar reinforced-concrete farms when building warehouses and other industrial-type rooms.

The main advantages of such designs:

• high strength properties;
• good rigidity;
• resistance to low temperatures;
• resistance to aggressive environments;
• fire safety.

Production of concrete elements of supporting structures

For the production of reinforced-concrete farms, concrete of structural type (light or heavy) is used, most often agloporibeton or expanded clay concrete. The manufacturing process itself is carried out in booths-chambers having one or several tiers on which steel molds with a steam jacket are mounted.

To create struts and braces laid during reinforcement, vibration tables with special cassette forms are used.

On the picture - reinforced concrete beams  and reinforced-concrete farms

Conventional rods are most often used as the upper belt for reinforcement, but the lower belts are equipped with high-strength wire, Ø 5 mm, which is assembled into string packages. To tension the latter, it is necessary to use hydraulic jacks, after which a concrete mixture is added there.

After 2-3 hours, the product is sent to the heat treatment workshop. At each manufacturing process, quality control of prestressed products is carried out.

Labeling process

For marking such material, letters and numbers written with a hyphen are used.

The letters indicate the size and type of the workpiece, and the numbers indicate, including:

• additional information;
• bearing ability;
• brand of concrete used.

With the help of letters, such a characteristic of concrete as permeability is also displayed, which shows how adapted the structure is to operation under aggressive conditions:

• the letter "P" means reduced fitness;
• using the letter "H" displays normal fitness;
• products that can withstand 8-point seismological phenomena are indicated by the letters "C".

Structural features of reinforced concrete trusses

The farm acts as a skeleton that displays what shape the roof will have. In order for the frame to differ in rigidity, strength and stability, it must be made using a large amount of steel and reinforced materials, which greatly complicates its design. Only such a design can ensure the safety of the building even in extreme weather conditions ().

However, all the same, manufacturers are trying in every possible way to reduce the weight of such a "skeleton". This is achieved, first of all, due to the use of lightweight concrete, which has no effect on the overall strength of the structure.

A traditional component of the internal structure of reinforced concrete trusses is high-strength reinforcing steel, which easily resists corrosion. Due to this, moisture ingress or severe frosts in no way can affect the strength of the roof.

Two belts working on bending act as its contour, but the struts and braces responsible for axial force are a lattice.

There are such main varieties of such farms:

1. Segmentedfor which the outline belt and the diagonal lattice are characteristic.
2. Polygonalwhen the belts are parallel or trapezoidal.
3. Archedcharacterized by rigid nodes.
4. Arched diagonalhaving an upper belt with curved outlines, as well as a rare lattice.

Quite often, polygonal trusses with even elements of the upper zone replace segment ones. This method is more economically feasible.

In addition, there is such a classification of farms:

• slanting.
• skinless.
• typical.

Scope of various types of farms

1. If the roof is planned to be built steadily, the best option would be to use diving farms, in the upper zone of which additional racks are installed. Most often, such buildings are equipped with a large number of communication systems. The step for them is 6 or 12 m.
2. When the building is single-span, and its heating is not planned, the ideal option would be to use dowel-free structures.
3. Pitched roofs are equipped with a segmented bevelless or slanting frame.

When overlapping one-story buildings with one or more spans of rolled materials, it is best to use typical concrete products.

There are many such options at present, let's dwell on their notation:

• FS - diagonal products used on pitched roofs;
• FBS - bezkrasosny type of trusses used for pitched roofs;
• FP - products used as a slab coating, the length of which is similar to the span;
• FPM - used on low-slope roofs without prestressing;
• FPN - for a roof with a small slope and prestressed racks;
• FBM - dummy products used on steep pitched roofs;
• FPS - found on pitched roofs;
• FT - trusses of a beadless type with a triangular outline.

Installation Nuances

Before installing such structures, it is necessary to calculate the bearing capacity of the building as accurately as possible. Mounting is carried out to located on bearing wall  or column embedded parts.

Tip: you should not start installation without making sure that the quality of the elements and their sizes are fully consistent.

In addition, you will need the services of a welder who will have to connect the embedded parts and supports. Metal runs are also welded to the first, due to which the optimal value of the longitudinal rigidity of the frame is achieved.

Depending on the form, a reinforced concrete farm can be:

1. Segmented.
2. Arched diagonal.
3. Arched bezrabosnoy.
4. Polygonal.

The whole process of manufacturing such structures is carried out in accordance with GOST on concrete or reinforced concrete structures.

Rafter ready concrete goods

Despite the high strength and reliability, such designs are rarely seen in private homes. This is explained by the complexity of the installation and the significant mass of the resulting roof. But most often, the reinforced concrete data can be seen on buildings whose span exceeds 18 m, and the step is within 6-12 m.

If the span is less than 18 m, it will be more advantageous to use beams, however, if there are a large number of communications located inside the frame, it is best to choose reinforced concrete. But when developing buildings whose spans exceed 30 m, it is necessary to take into account the total weight of the roof, which will be significant. Therefore, it will be rational to break them into separate blocks, however, at the same time, the price of work increases significantly.

If you look from the point of view of price / quality ratio, then the most optimal options will be segmented or arched. On such farms, changes in effort on the belts practically do not occur, while the height of their support is small, as a result of which the total weight of the structure, as well as the height of the walls, is minimized.

Production of reinforced concrete farms

The simplest production process is for the arched dowel-free type, the nodes of which are reinforced very simply. All received internal space can be filled with taps for various communication systems. Most often used in the installation of steep, flat or pitched roofs.

For the production of such material, concrete of the grade B30-B60 is taken, which has high strength characteristics. Reinforcing ropes, high-strength wire or bar reinforcement can constitute its lower belt.

In addition, light wire frames are also used, which prevent cracking during operation. To make it easier to crimp the lower belt, it is recommended to use frame lengths of less than three meters.

But for reinforcing the elements of the lattice and the upper belt, welded reinforcing cages are used, which are installed in two in the support nodes. As a result of this, the strength of the carcass along inclined sections increases. A set of transverse 6-10 mm rods, the spacing of which is 100 mm, makes up the welded frame used to reinforce the intermediate nodes of both belts.

For transportation of ready-made structures, specially equipped equipment is used, for example, the FKP-16 farm locomotive. Due to increased demand for steel structures  lightweight type, the demand for reinforced concrete products is falling. However, according to fire-fighting requirements, the best are reinforced-concrete farms.

Conclusion

The constructions presented in the article refer to massive construction, which cannot be done with your own hands; it is better to use special equipment for this. The manufacture of these products should also be given to professionals using modern materials and technologies for calculating the load ().

These concrete products are indispensable in the construction of buildings requiring wide spans. The video in this article will help you find additional information on this topic.

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Delivery

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• Glazing of shopping centers and car dealerships

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Making metal trusses cost

Tula Plant of Metal Structures Metallkompozit will manufacture metal trusses for various purposes according to the drawings, metal trusses for various purposes, truss trusses, truss trusses, floor trusses from profile pipes and corners.

Production of metal trusses for roofing

The cost of manufacturing metal trusses (size)

Complete factory readiness for installation will be 40 microns:

10-20 tons - from 65,000 rubles / ton

30-50 tons - from 63000 rub / ton

from 50 tons from 58000 rub / ton

To erect the roof of any type of building, including storage, industrial and commercial premises, metal farms are used today. They withstand heavy loads and are applicable where a large span is required.
Metal trusses  - A kind of lattice structure, composed mainly of rectilinear elements that form a geometrically constant structure and are interconnected in nodes. Metal in such structures is used more rationally than in beams, which makes them more economical.
   The main elements of metal trusses are belts and a lattice consisting of racks and braces. The connection in the nodes of the elements is carried out by their direct adjacency to each other by welding belts to the rods of the lattice.
   Metal consumption farms are very economical. They have good rigidity, which makes it possible to reduce their height. They can be flat and spatial. For flat trusses, the load is perceived only in one plane, needing to be fixed by ties. Spatial can take a load from any plane (any direction), where each face will be a flat truss.
   Are used steel trusses for roofing various buildings, superstructures of additional floors of existing buildings, during the construction and reconstruction of power lines, for the construction of transport galleries, etc. Metal structures give the opportunity to cover large unsupported spans and areas of 500 square meters. meters, while being absolutely reliable. The use of steel trusses well affects the inhabitants of the under-roof space, which is important in the construction of sports, entertainment or retail facilities, as well as in the reconstruction of attics.
   Beams, girders, metal trusses are steel building construction. The safety of buildings directly depends on them. They must withstand any possible stress. That's why every steel plant  must adhere to the standards introduced for these products.
   You can not save on reliability. In the construction of ceilings and other objects, all components must have impeccable quality: metal trusses, ties, gaskets, longitudinal and transverse beams, as well as everything that can be included in the metalwork sending kit.
   The manufacture of farms is a complex process, which is the installation of a system of rods, which will be able to maintain its shape regardless of what loads will be applied to it.
   The responsible appointment of these structures requires the implementation of GOSTs: from general specifications for all types of metal structures to standards for metal truss manufacturingproduced by welding from welded profiles with a rectangular section or from bent profiles.
   Farms can be divided by static schemes into:
   . girder (applicable for the construction and strengthening of bridges and buildings, they are easy to install and manufacture, do not need to install support nodes);
   frame (they are used for the construction of public buildings: pavilions, spectacular halls, covered markets, supermarkets and others);
   arched (increase the size of the object and the fence, their disadvantage can be considered a large consumption of metal);
   cable-stayed (used as beam for covering buildings and construction of bridges).
   Where moving loads are constantly operating, a combined type of structure is used.
   Thus, the main advantages of metal trusses are high reliability and strength with a relatively small mass, as well as ease of manufacture and installation.

	Name	Size m	Weight kg	Price, rub
				New
	Truss truss FS-18-2,4 (L1)
	Truss truss FS-18-3,2 (L2)
	Truss truss FS-18-3.9 (L3)
	Truss truss FS-18-4.3 (L4)
	Truss truss FS-24-1.5 (L5)
	Truss truss FS-24-1.8 (L6)
	Truss truss FS-24-2,2 (L7)
	Truss truss FS-24-2,6 (L8)
	Truss truss FS-24-2.9 (L9)
	Truss truss FS-30-1,3
	Truss truss FS-30-1.5
	Truss truss FS-30-1.8
	Truss truss FS-30-2.0
	Truss truss PF-12-30 (L16)
	Truss truss PF-12-37 (L17)
	Truss truss PF-12-43 (L18)
	Truss truss PF-12-50 (L19)
	Truss truss PF-12-61 (L20)

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GOST 23119-78

UDC 69.024.8: 006.354 Group Ж34

STATE STANDARD OF THE USSR

Truss steel rafters welded with elements

from paired corners for industrial buildings

Technical conditions

Steel welded roof trusses of double angles

for industrial buildings. Specifications.

Validity from 01.01.1979

until 01/01/1984

APPROVED AND IMPLEMENTED BY Decree of the USSR State Committee of Ministers for Construction Affairs dated April 28, 1978 No. 73

Reissue. November 1979

This standard applies to steel welded rafter trusses with elements from paired corners connected to the Taurus, with a slope of the upper belt of 1.5%, designed for industrial buildings with spans of 18, 24, 30 and 36 m:

with a rolled and mastic roof;

with steel and reinforced concrete columns;

with non-aggressive and slightly aggressive environments;

erected in areas with a calculated outdoor temperature of minus 65 ° C and above and seismicity up to 9 points inclusive.

Rafter steel trusses must meet the requirements of GOST 23118-78 and the requirements set forth in the relevant sections of this standard.

1. The main dimensions

1.1. Farms should be made in height:

3150 mm - for spans of buildings 18, 24, 30 and 36 m;

2250 mm - for spans of buildings 18 and 24 m.

Farms with a height of 3150 mm for spans of buildings of 18 and 24 m should be used in buildings in which, along with spans of 18 and 24 m, there are spans of 30 and 36 m, as well as in buildings where, according to the conditions of production technology, an increased height of the inter-truss space is required. In other cases, the choice of trusses in height for spans of buildings of 18 and 24 m is based on a comparison of the technical and economic indicators of the options considered.

1.2. Schemes and basic dimensions of trusses must correspond to those indicated in Fig. 1. It is allowed to use additional lattice elements (trusses, elements for securing suspended transport ways, struts to reduce the estimated length of the main truss rods, etc.).

1.3. The division of farms into shipping elements must be in accordance with Figure 2.

DIAGRAMS AND BASIC DIMENSIONS OF FARMS

Damn. 1

SHARING FARMS FOR DELIVERY ELEMENTS

Trusses for spans of buildings 18 m

a) sent by one item is allowed

Trusses for spans of buildings 24 m

Trusses for spans of buildings 30 m

Trusses for spans of buildings 36 m

Damn. 2

2. Technical requirements

2.1. Farms should be manufactured in accordance with the requirements of this standard, GOST 23118-78 and SNiP III-18-75, according to the working drawings of KMD, approved in the prescribed manner.

2.2. The maximum deviations of the linear dimensions of the trusses and their parts from the nominal are given in Table 1.

Table 1

mm

Size name	Prev off	Sketch
Truss or Shipping Elements Length L, L 1, L 2; up to 8000 incl. st. 8000 "16000" " 16000	± 5.0 ± 6.0 ± 8.0
Height of trusses or sending elements (on supports and areas of mounting joints) H, H 1, H 2: 2250 3150	± 1.5 ± 2.0
The distance between the axes of the holes and the end face of the support rib l, l 1, l 2 The distance between the axes of the holes in the support rib A	± 0.8
The distance between the axes of the holes in the truss belts A, A 1, A 2, A 3, A 4	± 1.5
The distance between the groups of mounting holes A: up to 1600 incl. st. 1600 "2500" " 2500 " 4000 " " 4000 " 8000 " " 8000 " 16000 " " 16000 " 18000 "	± 2.0 ± 2.5 ± 3.0 ± 4.0 ± 5.0 ± 6.0

2.3. The maximum deviations of the shape and location of the surfaces of truss parts from design are given in table. 2.

table 2

mm

Name of deviation	Prev off	Sketch
up to 1000 incl. st. 1000 "1600" " 1600 " 2500 " " 2500 " 4000 " " 4000 " 8000 " " 8000 " 16000 " " 16000 " 18000 "	0,8 1,3 2,0 3,0 5,0 8,0 13,0
Non-perpendicularity of the end face of the supporting rib to the vertical axis of the truss	0,3
The offset of the ears of the paired corners in the plane of the farm: within mounting joints in other areas	0,5 1,0
Offset of center axes of truss rods in nodes	3,0	-

2.4. The roughness of the machined end surface of the support rib should not be rougher than the first class according to GOST 2789-73.

2.5. The distance between the edges of the parts of the grating and belts in the nodes of the trusses should be equal to 4-5 thicknesses of the gusset.

2.6. The upper truss belts with the thickness of the waist corners less than 10 mm in places of support of reinforced concrete slabs should be reinforced with overlays.

2.7. In the upper plane of the corners of the upper truss belts, in the case of support of reinforced concrete slabs on them, transverse risks should be applied with indelible paint, indicating the center of the node.

2.8. The details of the trusses, depending on the design temperature, should be made of steel grades listed in Table 3.

2.9. Welded joints of truss elements should be made mechanized.

It is allowed, in the absence of equipment for welding by mechanized methods, the use of manual welding.

Table 3

		Steel grade for buildings constructed at design temperature
Name	Assortment	minus 40 ° C and above		below minus 40 ° С
of details		Option 1. From steel of the same class	Option 2 From steel of two classes	up to minus 65 ° С
Belt	GOST 8509-72		C46 / 33
Grid element	GOST 8510-72		C38 / 23 or C46 / 33
Style		S38 / 23	S38 / 23	C46 / 33
Support rib	GOST 19903-74		C38 / 23 or C46 / 33
Butt pad

Notes:

1. Steel grades should be accepted in accordance with SNiP II-B.3-72 and SNiP II-28-73.

2. Option 1 or 2 is selected based on the results of comparing their technical and economic indicators.

2.10. Materials for welding should be accepted in accordance with SNiP II-B.3-72.

2.11. Farms must be primed and painted.

Primer and painting must correspond to the fifth class of coating according to GOST 9.032-74.

3. Completeness

3.1. Farms should be supplied in full by the manufacturer.

The kit should include:

farm shipping items

mounting gaskets 4, 6 and 8 mm thick in an amount equal to 85, 65 and 20%, respectively, of the total number of truss support nodes;

technical documentation in accordance with the requirements of GOST 23118-78.

4. Acceptance rules

4.1. Farms (sending elements) to verify compliance with the requirements of this standard should be taken by the technical control of the manufacturer individually.

4.2. Deviations of the linear dimensions of trusses and their parts (including sizes of sections of rolled profiles) from nominal, deviations of the shape and location of surfaces of parts from design, quality of welded joints and surface preparation for protective coatings should be controlled before trimming.

4.3. The control assembly must be subjected to the first and every tenth farm.

4.4. The consumer has the right to accept farms, applying the acceptance rules and control methods established by this standard.

5. Control Methods

5.1. Deviations of the linear dimensions of trusses and their parts from nominal, deviations of the shape and location of the surfaces of parts from design, as well as the roughness of the machined surface should be controlled by universal methods and means.

5.2. Quality control of welded joints and the size of their sections should be carried out in accordance with SNiP III-18-75.

6. Labeling, transportation and storage

6.1. Manufactured farms should be marked.

On each sending element of the farm shall be marked:

order number;

kMD drawing number, according to which the sending element of the farm was made;

designation of farms according to the CMD drawing with the serial number of the manufacture.

On each package of mounting gaskets, the order number and the number of the KMD drawing, according to which the gaskets are made, must be marked.

Each mounting gasket must have its thickness indicated.

Example of labeling a farm’s starting item:

,

where 310 is the order number;

5 - drawing number KMD;

B8 - reference designation;

6 - serial number of manufacture.

On the starting element of the truss markings should be applied on the first brace and on the outer plane of the lower belt, as well as on the package of mounting gaskets - at the top and bottom of the package.

Marks must be applied with indelible paint.

6.2. Farms (shipping elements) should be transported and stored in working position. At the same time, the trusses should rely on wooden linings installed near the nodes with a thickness of at least 50 mm during transportation and at least 150 mm when storing the farms at the construction site.

The length of the lining must exceed the width of the lower truss belt by at least 100 mm.

During transportation and storage, the reliability of the fastening of the farms and their safety from damage should be ensured.

During transportation, the sending elements of the trusses must be bundled. The mass of the package must be agreed with the consumer and not exceed 20 tons.

Mounting gaskets must be wired into packages.

7. Installation instructions

7.1. Installation of farms should be carried out in accordance with the requirements of GOST 23118-78 and SNiP III-18-75.

7.2. The maximum deviations from the design position of the mounted structures are given in table. 4.

Table 4

mm

Name of deviation	Prev off	Sketch
Deviation of the vertical axis of the upper belt from the vertical axis of the lower belt of the truss	5,0
The straightness of the compressed belts from the truss plane along the length of the section between the fastening points L: up to 4000 incl. st. 4000 "8000" " 8000 " 12000 "	5,0 8,0 13,0

7.3. The offset of the outer faces of the supporting parts of the reinforced concrete coating slabs from the transverse marks applied in accordance with clause 2.7 should not be more than 20 mm.

8. Manufacturer's Warranty

8.1. The manufacturer must guarantee that farms comply with the requirements of this standard, subject to the conditions of transportation, storage and installation established by this standard.

Reinforced concrete trusses  3FBS 18

The general element of the device of any object is the roof, the safety of the building and ease of use directly depend on the correct device of the roofing elements. Today, the construction industry proposes to use rafter reinforced concrete trusses - load-bearing roofing structures that redistribute their mass and additional load from the snow cover to the foundations of the walls of the building. Also, farms can better withstand wind loads and various natural anomalies. To create pitched roofs, rafters and sub-rafter beams are also often used in accordance with GOST 20372-90.

Types of rafter reinforced concrete structures

The farm can be described as complex reinforced concrete productconsisting of an external contour and a lattice. The contour of the truss is formed by two belts that work on bending. And the lattice inside the circuit - braces and racks, withstand axial loads.

Depending on the design of the circuit and the lattice, you can divide the truss into:

• Segment reinforced concrete trusses - have an original upper belt and a diagonal lattice, they are necessary for pitched roofs;
• Polygonal - in such concrete goods, the belts are either parallel or trapezoidal, with a diagonal lattice inside. The upper belt has a slight slope.
• Arched bezkrasosny - have hard knots;
• Diagonal arched - have a rare lattice and curved outlines of the upper belt.

Modern manufacturers use modified concrete and complex steel reinforcement systems to produce the most durable structures. The latest technologies make it possible to create any geometric shapes from reinforced concrete, but today farms of the most rational design are used: segmented, with parallel belts and gable trapezoidal with a straight or broken lower belt. The grid of farms, as a rule, is formed triangular or supplemented by uprights or braces. Naturally, when choosing and constructing 3FBS 18 trusses, extreme operating conditions are also taken into account, therefore, these supporting structures have a certain margin of safety. Truss reinforcement is a complex system of welded frames, which ensure the preservation of the shape and perception of high loads.

A farm is a framework that will determine the future shape of the roof and the characteristics of the distribution of loads. The design of this type of concrete goods can vary significantly depending on engineering solutions, however, several popular types are common in Russia, the shape of which is determined by. The farm gives the roof stiffness, strength, stability and allows you to distribute serious loads, so it is often used in areas with a large share of snow load, for example, in the Urals and Siberia.

Reinforced concrete farms of 18, 12 and 24 meters are the most popular in modern construction. Today they are manufactured according to the most modern standards according to the type drawings of the series 1.463.1-16, 1.463.1-3 / 87, 1.063.1-1, PK 01-110 / 81, 1.463.1-4 / 87 and the series 1.463.1 -fifteen. In the "Reinforced Concrete Products Handbook" of the Complex-S company, you can always purchase any standard sizes of roof trusses with delivery throughout Russia and Kazakhstan. Rafter reinforced concrete structures are made with prestressing reinforcement (depending on the load on the trusses it can be wire, rod, rope, stretched to the stands of the stand). The lower truss belt is reinforced in a special way. Rigid roofing panels, which play the role of bonds, are welded in the nodes along the upper zone of the farm. The trusses are mounted on the head-ends of reinforced concrete columns; they are fastened by means of anchor bolts and welding of embedded supporting products.

Reinforced concrete truss structure

From an engineering point of view, triangular farms are the most irrational in terms of geometry. They have a large height and require significant material costs. The use of such structures can only be justified when selling roofs with a large slope of sheet materials (metal, asbestos cement).

The most practical design is called segmented or arched reinforced concrete trusses with a broken or curved upper belt. Such trusses distribute the forces in the belts more evenly, and the lattice forces are reduced compared to trusses of a different shape. Segment and arch trusses have an average height indicator on the support, which allows to reduce the height of the walls of a one-story building. Other designs - trapezoidal trusses and concrete products with parallel belts have a more pronounced height on the support, which increases the consumption of material and, naturally, the prices of reinforced concrete trusses. Such products are heavier than arched and segmented, but less labor intensive in operation.

Reliable rafters made of heavy concrete provide maximum strength and durability of the building, they make it easy to operate much longer. Different types of farms allow you to form buildings with spans of up to 24 meters, with different types of roofs (low-sloping or pitched). Also, the coating can be equipped with flashlights, which are most often used in industrial and warehouse facilities with a high degree of responsibility.

Truss and sub-truss trusses in the first place, bearing parts of the roof, specialists should be involved in their calculation, design and installation. The use of reinforced concrete trusses may be limited due to their mass - the weight of the 3FBS 18 truss is 9,200 kg. As a rule, reinforced concrete farms are used for the installation of one-story buildings with a solid area. Often they are necessary for construction in difficult conditions of the Russian climate.

Types of reinforced concrete farms

Reinforced concrete trusses may vary in size and type depending on the design. Key decisions include:

Trusses reinforced concrete rafters:

• FS - diagonal trusses in the form of segments for covering buildings with a pitched roof;
• FBS - seedless truss farms for covering objects with a pitched roof type;
• FBM - for covering buildings with a steep roof.
• FT - triangular bezkrasochny for coverings of buildings with a pitched roof.

Reinforced concrete trusses are divided into:

• FPS - a farm for coatings with a pitched roof;
• FPM - trusses for coatings with a steep roof;
• FPN - trusses for a low-slope roof with prestressed racks;
• FP - for coatings of plate type with a length of one span.

In the catalog of the company "Complex-S" you will find any farms with delivery throughout Russia. You can also order individual production of concrete goods from us.

Reinforced concrete truss marking

Traditionally, reinforced concrete trusses are marked with a cipher consisting of an alphanumeric combination.

The first group indicates the size of the reinforced concrete products (farm serial number), as well as the design type and length of the product in meters (rounded to the nearest whole).

In the second part, the serial number of reinforced concrete products is indicated according to the bearing capacity, the class of prestressed reinforcement, the type of concrete (for light-concrete products).

The third labeling group is optional; it may include factory product information. For example, resistance to the influence of aggressive environments, seismic activity, the presence of additional embedded parts, the permeability of concrete.

For example, consider a farm 1FPS 12-6AIVL-C  (11960x550x2200 mm), where:

• 1 - farm size;
• FPS - a truss for pitched roof;
• 12 - length in meters;
• 6 - bearing capacity index;
• AIV - class of prestressed reinforcement;
• L - lightweight concrete;
• C - application is permissible with seismicity up to 8 points.

On the surface of the reinforced concrete products, the brand, mass, batch release date and OTK stamp are also indicated.

The calculation of roof structures of complex shape requires the possession of information from standard series and. Specialists of the Complex-S company are always glad to help with the choice of reinforced concrete farm. It is also worth considering objective indicators:

• The weight of the farm and the entire roof system with a roof;
• The mass and the effect of additional loads - snow and wind;
• Additional temporary and periodic loads from vibrations, seismic activity, etc.

Reinforced concrete trusses are distinguished from other types of truss structures by high strength, rigidity and crack resistance. Also concrete products  do not burn, do not rot, do not suffer from corrosion. High frost and moisture resistance allow use in any climatic conditions.

Often, technologists try to lighten the farm as much as possible in order to reduce both the price of reinforced concrete products and the pressure on the base of a one-story building. Often, light concrete is used for this purpose, which, without loss of quality, can reduce weight reinforced concrete structure. The inner part of the farm includes high-quality reinforcing steel with anti-corrosion treatment, so the roofing of the building is reliably protected from the effects of precipitation, condensation and temperature changes. For industrial buildings, reinforced concrete products are also especially resistant to various types of chemical corrosion. In the company "Complex-S" you can order farms of popular and complex designs with delivery throughout Russia and Kazakhstan. We work with leading manufacturers and always ensure the speed and care of the supply of reinforced concrete products.