Reinforced concrete lintels GOST 948 84 download pdf. Jumpers with prestressing reinforcement At-V

30.10.2021

INTERSTATE STANDARD

REINFORCED CONCRETE LINDERS
FOR BUILDINGS WITH BRICK WALLS

Specifications

IPK STANDARDS PUBLISHING HOUSE
Moscow

INTERSTATE STANDARD

Date of introduction 01.01.86

This standard applies to reinforced concrete lintels made of heavy concrete and designed to block openings in brick walls buildings for various purposes.

It is allowed to use jumpers to cover openings in walls made of artificial and natural stones.

Jumpers intended for operation under the influence of an aggressive environment, as well as in buildings with a design seismicity of 7 points or more, must meet additional requirements established by the design documentation of the building in accordance with the requirements of SNiP II-7 and specified in the order for the manufacture of jumpers.

1. TYPES, MAIN PARAMETERS AND DIMENSIONS

1.1. Jumpers are divided into the following types:

PB - bar, up to 250 mm wide inclusive. (dev. 1);

PP - slab, more than 250 mm wide (Fig. 2);

PG - beam, with a quarter for supporting or adjoining floor slabs (Fig. 3);

PF - facade facing the facade of the building and designed to cover openings with quarters with a thickness of the protruding part of the masonry in the opening of 250 mm or more (Fig. 4).

Jumper type PB

1 - technological bias

Jumper type PP

1 - technological bias

Jumper type PG

Jumper type PF

1.2. The shape, dimensions and indicators of material consumption (consumption of concrete and steel) of lintels for brick walls with a thickness of 65 mm must correspond to:

PB type - indicated on hell. 1 and in table. one;

» PP » » » 2 » » » 2;

» PG » » » 3 » » » 3;

» PF » » » 4 » » » 4.

1.3. The shape, dimensions and indicators of material consumption (consumption of concrete and steel) of lintels for brick walls with a thickness of 88 mm must correspond to:

PB type - indicated on hell. 1 and in table. 5;

» PP » » » 2 » » » 6;

» PF » » » 4 » » » 7.

1.4. Jumpers of PB and PP types are allowed to be manufactured with a technological slope of the side and end faces. In this case, the dimensions of the lower face of the jumper may be smaller than the corresponding dimensions of the upper face: length - up to 20 mm, width - up to 8 mm (Fig. 1 and 2).

1.5. Concrete grades for frost resistance of lintels are assigned depending on the values of the calculated winter temperatures of the outside air in the construction area in accordance with the instructions in the application.

1.6. Of the PB and PP types of lintels provided in two reinforcement options (with prestressed and non-stressed longitudinal reinforcement), prestressed ones should be used predominantly.

1.7. Jumpers are made with sling holes with a diameter of 30 mm, provided for lifting and mounting jumpers using special gripping devices, or with mounting loops.

In cases provided for by the design documentation of a building with a design seismicity of 7 points or more, lintels may have reinforcement outlets and embedded products.

Table 1

Jumper brand				Consumption of materials
	Length l	Width b	Height h	Concrete, m 3	Steel, kg























































































5PB21-27 AtV
5PB21-27 AtV-a
5PB25-27 AtV
5PB25-27 AtV-a
5PB25-37 AtV
5PB27-37 AtV
5PB27-27 AtV
5PB27-27 At-V-a

5PB30-27 AtV-a
5PB30-37 AtV
5PB31-37 AtV
5PB34-20 AtV
5PB 36-20 AtV

5PB21-27 AtIVC
5PB21-27AtIVC-a
5PB25-27 AtIVC
5PB25-27 AtIVC-a
5P 25-37 AtIVС
5PB27-37 AtIVC
5PB27-27 AtIVC
5PB27-27AtIVC-a
5PB30-27 AtIVC
5PB30-27 AtIVC-a
5PB30-37 AtIVC
5PB31-27 AtIVC
5PB34-20 AtIVC
5PB36-20 AtIVС

table 2

	Jumper brand	The main dimensions of the jumper, mm			Consumption of materials		Jumper weight (reference), kg	Type issue designation project documentation series 1.038.1-1
	Jumper brand	Length l	Width b	Height h	Concrete, m 3	Steel, kg	Jumper weight (reference), kg
Jumpers with non-tensioned fittings


















Jumpers with prestressing reinforcement At-V
	3PP14-71 AtV
	3PP16-71 AtV
	3PP18-71 AtV
	3PP21-71 AtV
	3PP27-71 AtV
	6PP14-72 AtV
	6PP16-72 AtV
	6PP18-72 AtV
	6PP21-72 AtV
	6PP27-72 AtV
Jumpers with prestressed reinforcement class At-IVС
	3PP14-71 AtIVС
	3PP16-71 AtIVС
	3PP18-71 AtIVС
	3PP21-71 AtIVС
	3PP27-71 AtIVС
	6PP14-72 AtIVC
	6PP16-72 AtIVС
	6PP18-72 AtIVС
	6PP21-72 AtIVC
	6PP27-72 AtIVС

Table 3

Jumper brand	The main dimensions of the jumper, mm				Consumption of materials		Designation of the issue of standard design documentation of the series 1.038.1-1
Jumper brand	Length l	Width b	Height h	quarter height h 1	Concrete, m 3	Steel, kg

Table 4

Jumper brand	The main dimensions of the jumper, mm				Consumption of materials		Jumper weight (reference), kg	Designation of the issue of standard design documentation of the series 1.038.1-1
Jumper brand	Length l	Height h	Protrusion Height h 1	Support zone length a	Concrete, m 3	Steel, kg	Jumper weight (reference), kg

Table 5

	Jumper brand	The main dimensions of the jumper, mm			Consumption of materials		Jumper weight (reference), kg	Designation of the issue of standard design documentation of the series 1.038.1-1
		Length l	Width b	Height h	Concrete, m 3	Steel, kg
Jumpers with non-tensioned fittings


































	10PB21-27-ap

	10PB25-27-ap









	10PB27-27-ap
Lintels with prestressed reinforcement class Ат-V
	9PB18-37 AtV
	10PB18-27 AtV
	10PB21-27 AtV
	10PB21-27 AtV-a
	10PB25-27 AtV
	10PV25-27AtV-a
	10PB25-37 AtV
	10PB27-37 AtV
	10PB27-27 AtV
	10PB27-27 AtV-a
Jumpers with prestressed reinforcement class At-IVС
	9PB18-37 AtIVC
	10PB18-27 AtIVC
	10PB21-27 AtIVC
	10PB21-27 AtIVC-a
	10PB25-27 AtIVC
	10PB25-27 AtIVC-a
	10PB25-37 AtIVC
	10PB27-37 AtIVC
	10PB27-27 AtIVC
	10PB27-27 AtIVC-a

Table 6

	Jumper brand	The main dimensions of the jumper, mm			Consumption of materials		Jumper weight (reference), kg	Designation of the issue of standard design documentation of the series 1.038.1-1
	Jumper brand	Length l	Width b	Height h	Concrete, m 3	Steel, kg	Jumper weight (reference), kg
Jumpers with non-tensioned fittings


















Lintels with prestressed reinforcement class Ат-V
	8PP14-71 AtV
	8PP16-71 AtV
	8PP18-71 AtV
	8PP21-71 AtV
	8PP27-71 AtV
	10PP14-72 AtV
	10PP16-72 AtV
	10PP18-72 AtV
	10PP21-72 AtV
	10PP27-72 AtV
Jumpers with prestressed reinforcement class At-IVС
	8PP14-71 AtIVC
	8PP16-71 AtIVC
	8PP18-71 AtIVС
	8PP21-71 AtIVС
	8PP27-71 AtIVC
	10PP14-72 AtIVC
	10PP16-72 AtIVC
	10PP18-72 AtIVС
	10PP21-72 AtIVC
	10PP27-72 AtIVC

Table 7

Jumper brand	The main dimensions of the jumper, mm				Consumption of materials		Jumper weight (reference) kg	Designation of the issue of standard design documentation of the series 1.038.1-1
Jumper brand	Length l	Height h	Protrusion Height h1	Support zone length a	Concrete, m 3	Steel, kg	Jumper weight (reference) kg

Notes to the table. 1 - 7:

1. In the case of using reinforcing steel as prestressed longitudinal reinforcement class A-V instead of At-V or A-IV instead of At-IVC in the brand of prestressed lintels, the designation of reinforcing steel, respectively, AtV should be replaced with AV or AtIVC with AIV.

2. The design load on the lintel is given taking into account the own weight of the lintel.

3. The consumption of steel for a prestressed lintel is given for the nominal length of the prestressing reinforcement bars, equal to the length of the lintel. This consumption of steel should be clarified taking into account the actual length of the prestressing reinforcement, taken depending on the method of tensioning the reinforcement and the design of the gripping devices.

4. In the case of installation of rebar extensions and embedded products in lintels that are not provided for in the standard design documentation of series 1.038.1-1, the steel consumption per lintel should be changed accordingly.

5. The mass of jumpers is given for heavy concrete of average density of 2500 kg/m 3 .

1.8. Jumpers are marked with brands in accordance with the requirements of GOST 23009.

The jumper mark consists of alphanumeric groups separated by hyphens.

The first group contains an Arabic numeral indicating the serial number of the cross section of the bulkhead, the designation of the type of jumper and its length in decimeters (the value of which is rounded to the nearest whole number).

In the second group, the value of the design load on the lintel in kN / m (rounded to the nearest whole number) and the class of prestressing reinforcement (for prestressed lintels) are given.

In the third group, if necessary, indicate:

The presence of mounting loops, rebar outlets and embedded products in the lintels, indicated by lowercase letters (for example, the letter “a” - the presence of anchor outlets in the bar lintels for fixing balcony slabs; the letter “p” - the presence of mounting loops in the bar lintels);

Additional characteristics that ensure the durability of jumpers in operating conditions. For example, for lintels of buildings with a design seismicity of 7 points and above - resistance to seismic effects, denoted by a capital letter C; for lintels used under conditions of exposure to aggressive environments - characteristics of the degree of density of concrete (P - increased density, O - extra dense).

An example of a symbol (brand) of a jumper type PB 2460 mm long, cross-section No. 5 (according to Table 1), for a design load of 37.27 kN / m, with mounting loops:

5 PB25-37-n

The same, type PP 1810 mm long, cross-section No. 8 (according to Table 6), for a design load of 70.61 kN / m, with class At-V prestressing reinforcement:

8 PP18-71-A t V

The same, type PB 2070 mm long, cross-section No. 10 (according to Table 5), for a design load of 27.46 kN / m, with anchor outlets for fixing balcony slabs, with mounting loops:

10 PB21-27-an

The same, type PF 1940 mm long, cross-section No. 5 (according to Table 7), for a design load of 5.88 kN/m:

5 PF19-6

2. TECHNICAL REQUIREMENTS

2.1. Jumpers should be manufactured in accordance with the requirements of this standard and the technological documentation approved in the prescribed manner, according to the standard design documentation of the 1.038.1-1 series.

2.2. Jumpers must meet the requirements of GOST 13015.0:

By factory readiness;

By strength, rigidity and crack resistance;

According to the indicators of the actual strength of concrete (at the design age, transfer and temper);

On frost resistance of concrete;

To the quality of materials used for the preparation of concrete;

To concrete, as well as to materials for the preparation of concrete of lintels intended for operation in an environment with an aggressive degree of impact on reinforced concrete structures;

To the shape and dimensions of reinforcing and embedded products and their position in the lintel;

To steel grades for reinforcing and embedded products, including for mounting loops;

According to the deviation of the thickness of the protective layer of concrete to the reinforcement;

Corrosion protection;

On the use of molds for the manufacture of jumpers.

2.3. Lintels should be made of heavy concrete (with an average density of more than 2200 to 2500 kg / m 3 inclusive) of classes or grades in terms of compressive strength specified in the design documentation for these lintels.

2.4. The normalized transfer strength of concrete of lintels with prestressed reinforcement should be 70% of the class or grade of concrete in terms of compressive strength. The transfer of compression forces to concrete (reinforcement tension release) should be carried out after the concrete reaches the required normalized strength.

2.5. The normalized tempering strength of the concrete of the lintels should be (as a percentage of the class or grade of concrete in terms of compressive strength):

70 - when supplying jumpers in the warm season;

90 - the same, in the cold season.

2.6. Reinforcing steel should be used as prestressed longitudinal reinforcement of lintels:

Thermally strengthened classes At-V and At-IVC according to GOST 10884;

Hot-rolled classes A-V and A-IV according to GOST 5781.

2.7. Reinforcing steel should be used as non-stressed longitudinal reinforcement of lintels:

Hot-rolled class A-III according to

2.10. The stress values in the prestressed reinforcement, controlled after its tensioning on the stops, must correspond to those given in the design documentation for the lintels.

The values of the actual stress deviations in the prestressed reinforcement should not exceed 5% when tensioned mechanically, and when tensioned by the electrothermal method - the values, where l 1 - the length of the tensioned rod (the distance between the outer faces of the stops), in meters.

2.11. The values of the actual deviations of the geometric parameters of the jumpers should not exceed the limit values indicated in Table. eight.

Table 8

The name of the deviation of the geometric parameter	Geometric parameter name	Previous off
Deviation from linear dimension	Jumper length: up to 2500
	St. 2500 » 4000

	Jumper width and height
	Position of tabs, notches and holes
	The position of embedded products:
	In the plane of the jumper
	From the jumper plane
Straightness deviation	The straightness of the profile of the front surface of the jumper:
	Lengths up to 2500 at a given length of 1000
	The length of St. 2500 to 4000 for the entire length of the jumper
	The length of St. 4000 for the entire length of the jumper

2.12. The following categories of concrete surfaces of the lintel are established:

A3 - bottom and side surfaces;

A7 - other surfaces.

surface quality requirements and appearance jumpers - according to GOST 13015.0.

2.13. In the concrete of the lintels supplied to the consumer, cracks are not allowed, with the exception of:

Shrinkage and other surface technological cracks, the width of which should not exceed 0.1 mm;

Cracks from compression of concrete in prestressed lintels, the width of which should not exceed the values specified in the design documentation for these lintels.

3. ACCEPTANCE RULES

3.1. Jumpers should be accepted in batches in accordance with the requirements of GOST 13015.1 and this standard.

3.2. The acceptance of lintels in terms of their strength, rigidity and crack resistance, frost resistance of concrete, as well as water resistance and water absorption of concrete of lintels intended for operation in an environment with an aggressive degree of impact, should be carried out based on the results of periodic tests.

3.3. Acceptance of jumpers in terms of concrete strength (class or grade of concrete in terms of compressive strength, transfer and tempering strength), compliance of reinforcing and embedded products with project documentation, strength of welded joints, accuracy of geometric parameters, thickness of the concrete protective layer to reinforcement, width of opening of technological cracks, Concrete surface categories should be produced based on the results of acceptance tests and control.

3.4. In cases where it is found during the verification that the actual tempering strength of concrete is lower than the required tempering strength, then the supply of lintels to the consumer should be carried out after the concrete reaches a strength corresponding to the class or grade of concrete in terms of compressive strength.

3.5. The acceptance of jumpers in terms of the accuracy of geometric parameters, the thickness of the protective layer of concrete to the reinforcement, the category of the concrete surface, the width of the opening of technological cracks should be carried out based on the results of a single-stage selective control.

4. CONTROL AND TEST METHODS

4.1. The control and assessment of the strength, stiffness and crack resistance of the jumpers should be carried out in accordance with GOST 8829.

Load tests of lintels to control their strength, stiffness and crack resistance should be carried out when the concrete reaches a strength corresponding to its class or grade in terms of compressive strength.

4.2. The strength of the concrete of the lintels should be determined according to GOST 10180 on a series of samples made of concrete mix working composition. on a series of samples made from a concrete mixture of the working composition.

4.6. Methods for monitoring and testing reinforcing and embedded products - according to GOST 10922.

4.7. The measurement of stresses in prestressed reinforcement, controlled at the end of the tension, should be carried out in accordance with GOST 22362.

4.8. Methods of control and testing of raw materials used for the manufacture of jumpers must comply with established standards or specifications for these materials.

4.9. The dimensions, deviation from straightness, the thickness of the concrete protective layer to the reinforcement, the position of embedded products, the quality of concrete surfaces and the appearance of the jumpers should be checked by the methods established by GOST 13015.0 - GOST 13015.4.

5. MARKING, STORAGE AND TRANSPORTATION

5.1. Jumper markings - according to GOST 13015.2. Markings and signs should be applied on the end or top sides of each jumper. On the end side of the jumpers with sling holes (instead of mounting loops), the mounting sign "Top of the product" in accordance with GOST 13015.2 must be applied.

Allowed by agreement between the manufacturer and the consumer and design organization- the author of the project of a specific building, instead of marks, put on the lintels their abbreviated symbols adopted in the design documentation of a specific building.

5.2. Requirements for the document on the quality of jumpers supplied to the consumer are in accordance with GOST 13015.3.

Additionally, in the document on the quality of the lintels, the concrete grade for frost resistance should be given, and for lintels intended for operation in an environment with an aggressive degree of impact, water resistance and water absorption of concrete (if these indicators are specified in the order for the manufacture of lintels).

5.3. Jumpers should be transported and stored in accordance with the requirements of GOST 13015.4 and this standard.

5.3.1. Jumpers should be transported and stored in containers sorted by brands and laid in the working position.

It is allowed to transport and store jumpers stacked without containers.

5.3.2. Linings and spacers between rows of jumpers should be at least 25 mm thick and located vertically one above the other at a distance of 200 - 250 mm from the end of the jumper.

5.3.3. The height of the stack of jumpers should be no more than 2 m.

5.3.4. Lifting, loading and unloading of lintels should be carried out in packages by a crane using special lifting devices, and individual lintels - by gripping the mounting loops or the provided slinging holes.

5.3.5. When transporting, the jumpers should be laid in vehicles in the working position, with the longitudinal axis in the direction of traffic.

APPENDIX

Mandatory

GRADES OF CONCRETE LINDERS FOR FROST RESISTANCE

* The estimated winter temperature of the outside air is taken as the average air temperature of the coldest five-day period, depending on the construction area in accordance with SNiP 23-01.

INFORMATION DATA

1. DESIGNED State Committee for Civil Engineering and Architecture under the State Construction Committee of the USSR, the Ministry of Industry building materials USSR, Central Research and Design and Experimental Institute of Industrial Buildings and Structures (TsNIIpromzdaniy) of the State Construction Committee of the USSR

INTRODUCED by the State Committee for Civil Engineering and Architecture under the Gosstroy of the USSR

Bar lintels 2PB 13-1 (GOST 948-84) are special elements for overlapping in residential buildings or technical structures made of bricks of various openings. Thanks to2PB 13-1 (GOST 948-84) doors and windows can be inserted into such openings without the consequences of a collapse of the structure. Reinforced concrete bars are used in the arrangement of non-load-bearing walls in order to create reliable and durable structures.

have special mounting loops, which greatly facilitates their installation on the object. The strength of the structure is achieved by taking the main loads on the lintels from the upstream walls and other elements, thereby guaranteeing the reliability of the entire structure. It should be noted that these are absolutely non-combustible and environmentally friendly products, so the use in residential buildings completely safe and economically justified.

1. Variants of writing marking.

Data reinforced concrete block mark according toGOST 948-84 , according to which the serial number of the group, the type of product and its size ranges are indicated. The brand can be written in different ways:

1. 2PB 13-1;

2. 2PB 13-1 p.

2. The main scope.

Slab jumpers 2PB 13-1 (GOST 948-84) used in civil and administrative construction in the arrangement of window and door openings ranging in size from 1.2 to 2.8 meters. Brick walls for this brand of lintels should have a thickness of no more than 65 cm. The lintel is designed to take the weight from the upstream walls, the roof structure, as well as the load from its own weight.

Reinforced concrete products are also designed to work under static and dynamic loads with bending and compressive deformations. On thejumpers 2PB 13-1 (GOST 948-84) floor support is not provided, while the design load is 400 kgf / m (this load is not designed to work in the construction of load-bearing walls). Thus, the bar lintel is the main support used to strengthen the walls in window and door openings. When laying the bars, all seams are filled with cement mortar.

Reinforced concrete elements 2PB 13-1 (GOST 948-84) can be used in various aggressive environments. Due to the fact that these products are made of reinforced concrete, they can be used in aggressive environments, such as strong winds, low temperatures, as well as with a design seismic activity of up to 7 points on the Richter scale.

3. Designation of product marking.

Conditional markingbar jumper 2PB 13-1 (GOST 948-84) produced according toGOST 948-84 and include a designation by which you can determine the type of product and its main size groups, as well as technical characteristics and main purpose.

Decryption 2PB 13-1 (GOST 948-84) includes:

1. 2 - the serial number of the cross section of the bar;

2. PB - bar lintel;

3. 13 - size group, estimated length, in dm .;

4. 1 - design load in kN/m. The marking is indicated with rounding to an integer, for ease of writing;

5. Additionally, the following parameters can be specified: "P" - the presence of sling loops in the product; "A" - anchor releases, for fixing balconies; geometric volume of one product -0,0217 , volume of concrete - 0,021 .

Jumpers 2PB 13-1 (GOST 948-84) has the following dimensions -1290x120x140 , where the length or nominal height of the product, width and height are respectively indicated (rectangular section). The marking is applied to the side faces with special paint and additionally indicate the date of manufacture of the batch and the mass of the product (54 ).

4.Materials for manufacturing and main characteristics.

The main materials for the manufacturebar lintels 2PB 13-1 (GOST 948-84) are heavy concretes. Due to high grades, greater strength of finished products is achieved. So, use concrete grade M200 with a compressive strength class of at least B15. These materials are also characterized by high frost resistance (grades for 150 freeze-thaw cycles are used) and a certain water resistance - grade W2, the product is usually not exposed to the aquatic environment. The density of such concrete is about 2200-2500 kg/m3. A concrete bar lintel belongs to the category of fireproof structures that have a fire resistance limit of 1 hour.

Concrete goods enterprises produce products for construction industry. In the process of construction of residential buildings and industrial facilities, various types of standard products are used, including reinforced concrete lintels. They have high strength and are able to withstand bending loads, thanks to the reinforcing cage, filled with heavy concrete. Beams are manufactured according to requirements normative document 948 84. GOST classifies products by types, and contains a set of technical requirements.

Concrete lintels - device and purpose

How are jumpers arranged, according to the requirements of GOST? They consist of the following parts:

reinforcing mesh, which prevents the formation of cracks and increases the strength properties;
heavy concrete, the dimensions and shape of which, after hardening, comply with the provisions of the standard;
slinging elements designed for ease of transportation and ease of installation work.

The use of frost-resistant concrete makes it possible to operate products in the northern regions at temperatures down to minus 40 degrees. Reinforced with steel reinforcement, reinforced concrete crossbars are characterized by an increased margin of safety and do not crack as a result of application of bending loads.

Reinforced concrete crossbars are installed in the openings of buildings built from various materials:

all types of bricks;
aerated concrete blocks;
foam block building materials;
natural stone;
monolithic concrete.

It is difficult to imagine a house in which there are no windows or doors.

Reinforced jumpers perform a number of serious tasks:

increase the load capacity of openings;
form a flat surface during the construction of walls;
compensate for various types of existing loads;
close the power circuit above the window and door openings;
allow you to create a support contour for installing the roof.

Regulates construction areas in which reinforced concrete lintels can be used, GOST. The dimensions and design of the products make it possible to use them also in the transport sector for arranging crane runways, building overpasses and laying tram lines.

Main varieties

According to GOST 948, beams differ in marking and are divided into the following types:

jumpers PB. GOST classifies them as bar partitions having the configuration of a regular parallelepiped with a width of 0.25 m;
products with PP index. They are slab-like in appearance, with a minimum cross-sectional width exceeding 0.25 m;
L-shaped products, denoted by the letters PG. They have a longitudinally located ledge that improves docking with floor elements;
front crossbars with PF marking. The design provides for a quarter ledge for improved overlapping of openings from the street side of the building.

Depending on the magnitude of the workload, all prefabricated jumpers are divided into load-bearing and non-bearing

The current GOST for bar lintels provides for versions with inclined end surfaces and side faces. In this case, the dimensions of the support plane are slightly reduced, which does not significantly affect the strength characteristics.

Marking of reinforced concrete lintels

The manufacturer of reinforced concrete beams at the end of each product applies a marking that meets the requirements of the regulatory document. It is a special designation, in the form of an alphanumeric set.

The marking contains the following data:

profile size corresponding to certain dimensions;
designation of reinforced concrete products corresponding to the classification;
length rounded to the nearest whole number of decimetres;
the value of the calculated value of the force, which is indicated in kN / m;
type of reinforcing bars used for stressed crossbars;
information about fastening elements and rigging eyes;
the possibility of using structural beams in special conditions.

The letter index in the designation contains additional information about the availability of outlets for anchoring and sling eyes:

the presence of protruding reinforcement intended for fixing balcony slabs is indicated by the letter "a";
the embedded elements or lifting eyes provided for by the beam design are indicated by the letter "b".

Marking and overall dimensions iron concrete structures specifies GOST 948-84

The marking provides for a special designation in capital letters for the possibility of continuous use of reinforced concrete crossbars in special operating conditions:

products for seismic zones contain index "C";
beams for aggressive environments are designated by the letter "P".

Consider how the marking of one of the variants of the reinforced concrete crossbar 5PB30-27 AtIVC-a is deciphered:

5 - type of reinforced concrete profile with dimensions of 22x25 cm;
PB - designation of a beam of a bar structure;
30 - product length in decimeters, the actual size is 2980 mm;
27 - the value of the design force indicated in kN / m, rounded to the nearest whole number;
AtIVC - abbreviation for reinforcing bars concreted in a stressed state;
a - an index indicating the presence of protruding rods for fixing the beam.

When deciding on the possibility of using reinforced concrete beams for solving specific problems, it is necessary to be able to decipher the marking. It contains complete information about the performance and design features of the product.

Concrete lintels - dimensions and weight of products

The dimensions of reinforced concrete lintels for windows and doors, as well as other types of beams, are regulated by the standard. The rounded dimensions of products with the PB marking are:

length 1–6 m;
width - 1.2–2.5 dm;
height - 0.65–5.85 dm.

The range is so diverse that it makes no sense to list all standard dimensions.

Beams with the designation PP have the following parameters:

length - 1.1–3 m;
width - 3.8–5.1 dm;
height - 0.65–2.2 dm.

PG brand products are characterized by the following dimensions:

a length of 1.5–6 m;
width equal to 2.5–5.1 dm;
height - 2.9–5.85 dm.

The dimensions of the PF crossbars, which differ in a standard width of 2.5 dm, are:

length - 0.8–4.3 m;
height - 1.4–2.9 dm.

The mass of the beams depends on the dimensions and ranges from 20 kg to 2.5 tons.

Size table according to 948 GOST

The dimensions of concrete lintels for all versions are contained in the tables of the normative document. Table values use professional builders and design specialists, selecting products to perform specific construction tasks.

The diameter of the fittings used directly depends on what type of reinforced concrete jumper will be made - brusque or slab

Along with the dimensions of the beams, the tables of the standard contain the following information:

product code and marking;
design loads;
reference weight;
the required amount of materials for the manufacture of products.

Tabular information allows you to select crossbars, taking into account the required margin of safety.

How to make reinforced concrete jumpers GOST 948

The manufacturing process can be carried out in production conditions or independently. To make your own, prepare:

wood or moisture-resistant plywood for the manufacture of formwork;
steel bars intended for reinforcing cage;
knitting wire, which allows you to securely fix steel reinforcement;
concrete mixture prepared in the volume required for pouring.

The algorithm for self-manufacturing crossbars is as follows:

Choose the type of crossbar that meets the requirements of the standard in terms of dimensions.
Develop a formwork drawing taking into account the configuration of the molded element.
Make a formwork form, ensuring its tightness and strength.

Reinforced concrete bar lintels are the most common type of products used to decorate openings in residential, industrial and civil structures.

Lay polyethylene to facilitate the removal of finished products.
Cut steel bars with a diameter of 10–12 mm into blanks.
Tie a lattice of 4 longitudinal rods with a knitting wire.
Lay the frame in the form on special linings (with an equal gap to the surface).
Prepare the concrete mixture of the required grade and pour into the formwork.
Plan the upper plane of the concrete mass and lay polyethylene on it.
Moisten the molded product periodically to maintain moisture.
Remove the crossbar from the mold one month after concreting.

This technology allows you to independently manufacture products with small dimensions, which are then mounted in the opening area. Large-sized and massive structures that take significant effort are manufactured at specialized enterprises.

Formwork and its strengthening

The technology also provides the possibility of pouring beams directly above the opening.

To ensure the strength of concrete structures reinforced with steel reinforcement, formwork is assembled in the opening area from the following materials:

metal sheets;
wooden boards;
moisture resistant plywood;
particle boards.

The height of the jumper is selected based on the calculated load on the opening

A form is assembled from blanks, which is fixed with wire or bars from possible deformations during concreting. It is important to consider how the formwork structure will be dismantled after the crossbar has hardened. For this, a polyethylene film is used, which is laid inside the mold or the metal surface is lubricated with oil. A reinforcing cage is placed inside the formwork, which ensures the integrity of the structure and does not allow displacement. Vertical supports should also be provided for additional fixing of the mold.

How to insulate reinforced concrete lintels GOST

To reduce heat losses in the area of openings blocked by crossbars, a heat-insulating layer of various materials is laid:

mineral wool;
extruded polystyrene foam;
ordinary foam.

The gaps between the window frame or door frame and the insulation are sealed using mounting foam.

GOST 948 84 "Jumpers" - basic provisions

The regulatory document provides extended information for builders and designers:

application area;

In a non-load-bearing wall, bar lintels are of the same size

product varieties;
dimensions of various types of products;
technical specifications;
marking features;
product acceptance rules;
quality control methods;
transportation rules;
storage specifics.

Compliance with the provisions of the standard guarantees the quality of the products.

How to calculate the size of reinforced concrete lintels

For the selection of crossbars, taking into account the strength characteristics and existing loads, it is necessary to correctly perform the calculation. It includes the following stages:

calculation of the load acting on the structure;
determination of the maximum permissible bending moment;
selection of the optimal section.

It is advisable to entrust the execution of calculations to professionals who own the calculation methodology and take into account all factors in full.

How to install bar jumpers (GOST 948)

Installation of bar crossbars is carried out by various methods:

manually - with a small mass of products;
lifting device - for massive structures.

Regardless of the installation method, it is important to control the horizontal position and tight contact with the wall surface.

When performing work, pay attention to the following points:

the height of the beam, which must be at least 5% of the height of the opening;
the width of the structure, which must fully rest on the surface;
the diameter of the reinforcing cage rods, which is from 10 to 14 mm;
immobility of the structure, which can be loaded a month after pouring;
workmanship and installation reliability, guaranteeing the absence of cracks;
thorough compaction of the concrete mix to remove air cavities.

In the process of manufacturing and installation of concrete crossbars reinforced with reinforcing bars, one should be guided by the provisions of the regulatory document. The products are in demand in the construction industry and provide an increased margin of safety, as well as the durability of building structures. When designing, it is necessary to focus on the provisions of GOST 948 84. This will avoid problematic situations associated with the formation of cracks and violation of the integrity of building structures.