State standard of the Union of the USSR. State standard of the USSR Formwork and its strengthening

REINFORCED CONCRETE JUMPERS FOR BUILDINGS

WITH BRICK WALLS

Specifications

Reinforced concrete lintels for brick wall buildings.

Specifications

OKP 58 2811.58 2821

Date of introduction 1986-01-01

APPROVED AND ENTERED INTO EFFECT by Resolution of the USSR State Committee for Construction Affairs dated November 28, 1984 No. 193

INSTEAD GOST 948-76

REISSUE. August 1991

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

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

Jumpers intended for operation in conditions of exposure to an aggressive environment, as well as in buildings with a calculated 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-28-73 and SNiP II-7-81 and specified in the order for the production of jumpers.

1. Types, main parameters and sizes

1.1. Jumpers are divided into the following types:

PB - timber, up to 250 mm wide inclusive (Fig. 1);

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

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

PF - facade, facing the facade of the building and intended 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).

1.2. The shape, dimensions and material consumption indicators (concrete and steel consumption) of lintels for walls made of bricks 65 mm thick must correspond to:

type PB - indicated in the drawing. 1 and in table. 1;

"PP - " " " 2 and in table. 2;

" PG - " " " 3 and in table. 3;

"PF - " " " 4 and in table. 4.

1.3. The shape, dimensions and material consumption indicators (concrete and steel consumption) of lintels for walls made of bricks 88 mm thick must correspond to:

type PB - indicated in the drawing. 1 and in table. 5;

"PP - " " " 2 and in table. 6;

"PF - " " " 4 and in table. 7.

1.4. Jumpers of types PB and PP can be manufactured with a technological slope of the side and end faces. In this case, the dimensions of the lower edge of the jumper may be smaller than the corresponding dimensions of the upper edge: 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 outdoor air temperatures in the construction area in accordance with the instructions of the mandatory application.

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

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

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

/ GOST 948-84. Reinforced concrete lintels for buildings with brick walls

Updated: 02/09/2006

GOST 948-84

Group Zh33

STATE STANDARD OF THE USSR UNION

REINFORCED CONCRETE JUMPERS FOR BUILDINGS

WITH BRICK WALLS

Specifications

reinforced concrete lintels for brick wall buildings.

specifications font>

OKP 58 2811.58 2821

Date of introduction 1986-01-01

APPROVED AND ENTERED INTO EFFECT by Resolution of the USSR State Committee for Construction Affairs dated November 28, 1984 No. 193

INSTEAD GOST 948-76

REISSUE. August 1991

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

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

Jumpers intended for operation in conditions of exposure to an aggressive environment, as well as in buildings with a calculated 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-28-73 and SNiP ii-7-81 and specified in the order for the production of jumpers.

1. TYPES, MAIN PARAMETERS AND DIMENSIONS

1.1. Jumpers are divided into the following types:

PB - timber, up to 250 mm wide inclusive (Fig. 1);

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

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

PF - facade, facing the facade of the building and intended 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).

1.2. The shape, dimensions and material consumption indicators (concrete and steel consumption) of lintels for walls made of bricks 65 mm thick must correspond to:

type PB - indicated in the drawing. 1 and in table. 1;

"PP - " " " 2 and in table. 2;

" PG - " " " 3 and in table. 3;

"PF - " " " 4 and in table. 4.

1.3. The shape, dimensions and material consumption indicators (concrete and steel consumption) of lintels for walls made of bricks 88 mm thick must correspond to:

type PB - indicated in the drawing. 1 and in table. 5;

"PP - " " " 2 and in table. 6;

"PF - " " " 4 and in table. 7.

1.4. Jumpers of types PB and PP can be manufactured with a technological slope of the side and end faces. In this case, the dimensions of the lower edge of the jumper may be smaller than the corresponding dimensions of the upper edge: 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 outdoor air temperatures in the construction area in accordance with the instructions of the mandatory application.

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

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

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

Jumper type PB

1 - technological bias

Crap. 1

Jumper type PP

1 - technological bias

Crap. 2

Jumper type PG

Precast concrete enterprises produce products for the construction industry. In the process of constructing 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 reinforcement frame filled with heavy concrete. Beams are manufactured in accordance with the requirements of regulatory document 948 84. GOST classifies products by type and contains a set of technical requirements.

Concrete lintels - design and purpose

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

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

The use of frost-resistant concrete allows the product to be used in 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 the application of bending loads.

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

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

It's hard to imagine a house that has neither windows nor doors

Reinforced lintels perform a number of serious tasks:

• increase the load capacity of openings;
• form a flat surface when building walls;
• compensate for various types of existing loads;
• close the power circuit over 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 also allow them to be used in the transport sector for the arrangement of crane tracks, the construction of overpasses and the laying of tram lines.

Main varieties

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

• PB jumpers. GOST classifies them as timber partitions having the configuration of a regular parallelepiped with a width of 0.25 m;
• products with the PP index. They are slab-like in appearance, with a minimum cross-sectional width exceeding 0.25 m;
• products with an L-shaped configuration, designated by the letters PG. They have a longitudinally located ledge, which improves the connection with the ceiling elements;
• façade crossbars marked PF. The design provides a quarter ledge for improved covering of openings on the street side of the building.

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

The current GOST for block lintels provides for design options with inclined end surfaces and side edges. At the same time, the dimensions of the supporting plane are slightly reduced, which does not have a significant effect on the strength characteristics.

Marking of reinforced concrete lintels

The manufacturer of reinforced concrete beams applies markings at the end of each product that meet 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 decimeters;
• the value of the calculated force, which is indicated in kN/m;
• type of reinforcing bars used for stressed beams;
• information about fastening elements and rigging eyes;
• Possibility of using structural beams in special conditions.

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

• the presence of protruding reinforcement intended for fastening balcony slabs is indicated by the letter “a”;
• The embedded elements or lifting eyes provided for by the beam design are designated by the letter “b”.

Marking and overall dimensions of reinforced concrete structures are specified by GOST 948-84

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

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

Let's look at how the marking of one of the variants of the reinforced concrete crossbar 5PB30-27 AtIVS-a is deciphered:

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

When deciding on the possibility of using reinforced concrete beams to solve specific problems, you must be able to decipher the markings. It contains complete information about the operational characteristics 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 marked PB are:

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

The assortment is so diverse that there is no point in listing all the 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.

Products of the PG brand are characterized by the following sizes:

• length 1.5–6 m;
• width equal to 2.5–5.1 dm;
• height – 2.9–5.85 cm.

The dimensions of the PF crossbars, differing in the standard width of 2.5 dm, are:

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

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

Size table according to GOST 948

The dimensions of concrete lintels for all designs are contained in the tables of the regulatory document. Table values ​​are used by professional builders and design specialists when selecting products to perform specific construction tasks.

The diameter of the reinforcement used directly depends on what type of reinforced concrete lintel will be made - block or slab

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

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

The tabular information allows you to select crossbars taking into account the required safety margin.

How to make reinforced concrete lintels according to GOST 948

The manufacturing process can be carried out in a production environment or independently. To make it yourself, you should prepare:

• wood or moisture-resistant plywood for making formwork;
• steel bars intended for reinforcement 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:

• Select the type of crossbar that meets the dimensional requirements of the standard.
• Develop a formwork drawing taking into account the configuration of the element being formed.
• Make the formwork, ensuring its tightness and strength.

Reinforced concrete beam lintels are the most common type of product used to design openings in residential, industrial and civil buildings

• Place polyethylene to make it easier to remove the finished product.
• Cut steel rods with a diameter of 10–12 mm into blanks.
• Tie 4 longitudinal rods into a lattice using tying wire.
• Place the frame in the mold on special pads (with an equal gap to the surface).
• Prepare a concrete mixture of the required grade and pour it into the formwork.
• Plan the top 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 produce products with small dimensions, which are then mounted in the opening area. Large-sized and massive structures that absorb significant forces are manufactured at specialized enterprises.

Formwork and its strengthening

The technology also makes it possible to fill beams directly above the opening.

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

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

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

A form is assembled from the blanks, which is fixed with wire or bars against possible deformations during concreting. It is important to think about how the formwork structure will be disassembled after the crossbar has hardened. For this, a polyethylene film is used, which is placed inside the mold or the metal surface is lubricated with oil. A reinforcement cage is placed inside the formwork, which ensures the integrity of the structure and prevents displacement. Vertical supports should also be provided for additional fastening of the form.

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;
• regular foam.

The gaps between the window frame or door frame and the insulation are sealed using polyurethane 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, the lintels are the same size

• types of products;
• 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 produced.

How to calculate the size of reinforced concrete lintels

To select crossbars, taking into account the strength characteristics and operating loads, it is necessary to perform the calculation correctly. 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 calculations to professionals who are familiar with the calculation methods and take into account all factors in full.

How to install block lintels (GOST 948)

Installation of block crossbars is carried out using 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 rest completely on the surface;
• diameter of reinforcement cage rods, ranging from 10 to 14 mm;
• immobility of the structure, which can be loaded a month after pouring;
• quality workmanship and reliability of installation, guaranteeing the absence of cracks;
• thorough compaction of the concrete mixture to remove air pockets.

In the process of manufacturing and installation of concrete crossbars reinforced with reinforcing mesh, 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 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.