Reinforced concrete purlins: dimensions and GOST standards

Reinforced concrete products of various shapes and sizes are of great importance for ensuring the strength of building structures. One of the common and popular types of such elements are reinforced concrete purlins, which are necessary in the construction of domestic, public buildings, administrative, warehouse and industrial buildings.

Using beams

Precast concrete purlins are used as load-bearing structures in buildings of various types and purposes - administrative, industrial, residential. The need to install additional beams is explained by the large roof area and the small number of support points. Most often, such products are used for the following purposes:

Reinforced concrete purlins - application

as a basis for floor slabs in order to increase their load-bearing functions;
to strengthen the installed rafter system;
in the form of reinforced concrete lintels over door and window openings;
when creating flat roofs with a slope of less than 5% (in some cases up to 25%);
in the form of connecting structures between individual elements of large buildings;
for the formation of technological niches.

Dimensions and support

Brand	Dimensions			Max opening width	Min support	Load kgf/m
Brand	Length	Width	Height	Max opening width	Min support	Load kgf/m
PRG28.1,3-4	2780	120	300	2420	180	4000
PRG32.1,4-4	3180	120	400	2820	180	4000
PRG36.1,4-4	3580	120	400	3220	180	4000
PRG42.2,5-4	4180	200	500	3780	200	4000
PRG48.2,5-4	4780	200	500	4380	200	4000
PRG54.2,5-4	5380	200	500	4980	200	4000
PRG60.2,5-4	5980	200	500	5580	200	4000

Product classifications

The classification of reinforced concrete girders is carried out according to several parameters - by cross-section, by shape and by type of reinforcement.

By section

Purlins are manufactured with different types of profile:

rectangular section. They have the shape of simple pillars that may have recesses;
T-bar. They have a T-shape in cross-section and are equipped with a shelf for laying slabs;
with one-sided shelf. The profile shape is L-shaped.

Reinforced concrete purlins by profile type

According to the shape of the shelf and type of reinforcement

Beams with a T-section are further divided into several types:

Table of sections of different sizes of reinforced concrete purlins

1PR. The placement of the shelf relative to the rib is at an angle of 90°, the reinforcement is formed from longitudinal rods;
2PR. The shelf is perpendicular to the rib, the reinforcement is tense, which increases the load-bearing capacity of the beam;
3PR. The shelf is placed perpendicularly, the frame is pre-stressed, used for roofs with a slight angle of inclination;
4PR. The shelf is at a slight angle, non-stressed reinforcement, used for roofs with a large angle of inclination;
5PR. Main characteristics - the shelf is installed at a slight angle and there is a prestressed frame.

Main features of this type of structure

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

Strength	The design load of the products must be at least 4,000 kgf/m, which allows the elements to be used in the construction of load-bearing walls.
Types of sections	There are two types of sections: rectangular and T-shaped. In construction reference books you can also find Z-shaped and C-shaped purlins, but they are a metal profile and are not used as elements of load-bearing structures.
Production material	The manufacturing material is heavy concrete grade M250, and for structures 6 meters long or more it is necessary to use the even more durable grade M350.
Reinforcement	There are two main options for reinforcement: unstressed, consisting of a spatial steel reinforcement frame, and stressed, consisting of prestressed reinforcing bars and a spatial frame.
Installation features	It is important to remember that the weight of the products is very large and it is unlikely that you will be able to carry out installation work yourself - you will need lifting equipment. It is for this reason that purlins are not often used in private development.

Important! Do not confuse purlins with jumpers. Lintels are used for similar purposes, but are much smaller in size and are not designed for heavy loads and cannot be used in load-bearing systems. Purlins are suitable for any purpose: from strengthening openings (especially large ones) to creating additional strength in places where reinforced concrete slabs support.

Purlins are much larger and more massive than jumpers

Marking of reinforced concrete beams

Products made of reinforced concrete are marked taking into account the type of their section.

Rectangular . Marking of rectangular cross-section purlins are marked as follows - PRG 60.2.5-5AIII, where:

PRG – rectangular section;
60 – length 6 m;
2 – width 20 cm;
5 – height 50 cm;
5 – permissible load 500 kg/p. m;
АІІІ – type of fittings used.

Rectangular purlins - marking

T-bars . Beams with a T-section have a completely different marking - 2PR-1 AtIV-P, where:

2PR – beam type;
1 – number responsible for the load-bearing capacity of the structure;
AtIV – class of fittings used;
N – the property of concrete to resist the negative effects of aggressive environments (N – impenetrable, P – reduced permeability).

PR 60.5.5-7 AIII

Characteristics of reinforced concrete purlins

The designation of PRG products, in addition to the letter combination, also contains groups of numbers. The first group of numbers contains information about the dimensions of the product, the second gives an idea of the design load parameters without taking into account its own weight.

For example, the product designation PRG 32-1.4-4t is deciphered as follows:

PRG – rectangular purlin,
32-1.4 – length 320 cm, thickness 10 cm, height 40 cm,
4t – parameters of the design load without taking into account its own weight (in tons per meter).

Specific parameters are selected depending on the dimensions of the openings to be closed and the created ceilings in strict accordance with the project.

For those who work with the ZhBI-4 plant on an ongoing basis, special terms of cooperation are provided. We provide services for the delivery of purchased products to the customer’s site.

Technical specifications

For the manufacture of reinforced concrete purlins PRG or PR, heavy types of concrete are usually used, which provides them with excellent load-bearing qualities. Their properties are selected taking into account the length of the product and the characteristics of its reinforcement:

Characteristics of purlins of different brands

M200. Used when the length of the beam does not exceed 3.5 m;
M250. Length within 3.1 m;
M300. With spatial reinforcement, length up to 6 m;
M350. Combined with prestressed reinforcement, product length up to 6 m.

For the manufacture of beams, dense concrete is used, where this indicator reaches a value of 2500 kg / cubic meter. m. Therefore, the weight of one product is quite impressive - no less than 150 kg. The bearing capacity of such girders is no less than 39.2 kN/m.

The range of runs is impressive. Factories produce a huge number of products with different technical characteristics. But even when it was not possible to find a suitable beam, you can always order a purlin of intermediate sizes.

Explanation of markings

Beams have different markings. For example, rectangular purlins are marked as follows: PRG 40.2.5−4AIII. Decryption occurs as follows:

PRG - rectangular shape;
40 - beam length is 400 cm;
2 - width 20 cm;
5 - height 50 cm;
4 - maximum pressure of approximately 4 quintals per m.p.;
AIII - configuration of rods.

These are not the most accurate parameters, but approximate ones. For example, sometimes a separate product can be 419 cm long; on the marking it looks like PRG 42. Some beams at the end of the marking are marked with the letter “P” - this indicates that the purlin is made of heavy concrete. T-bar reinforced concrete products 1.255−2 series are designated by a different marking (2PR-1 AtV-N). It deciphers like this:

2PR - by beam type;
1 - serial numbering of bearing capacity;
AtV - classification of rods;
N - this means that the permeability of aggressive substances is normal; in some beams, “P” is placed instead of “N”, which indicates reduced permeability, and purlins with this letter are used in conditions of an aggressive environment.

Some manufacturers express the load-bearing capacity of purlins in different ways: sometimes in centners, kilonewtons, but mostly in kilograms.

Regardless of the size of the run length, the maximum pressure per meter will be approximately 400 kg. Slight deviation is allowed.

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Features of installation of purlins

The technology for installing reinforced concrete girders is quite difficult. This is due to their impressive weight and large dimensions. Such products cannot be installed in the design position manually. For this purpose, special lifting equipment is used. To move the purlins from above, there are special loops or through holes on their surface, which ensures a reliable grip.

Purlin installation diagram

Four workers are usually involved in installation. Two of them are riggers below, who secure the run for later movement. Two more builders are at the site where the beam is being installed.

The purlins are always laid horizontally, supported by walls, columns, and reinforced concrete pads. They must be additionally fixed using cement mortar and welding of embedded parts. As a result, an additional stiffening rib is formed as part of the created structure.

After completing the installation work, they proceed to installing the roofing pie, taking into account the requirements of the project. If reinforced concrete purlins were used to strengthen the floor, proceed to the installation of slabs and other necessary elements.

Application area

The products are made from high-quality high-density concrete grades M200-M600. This material is waterproof, fireproof, frost-resistant and does not crack. Reinforced concrete purlins can be used for different purposes:

they are used to install roofs with a slope of at least 5°;
contribute to additional strengthening of the truss structure;
serve as the basis for interfloor slabs;
used as connecting elements between several separate sections of large structures;
installed above window and door openings in places subject to increased loads.

For reinforced concrete purlins there are special conditions for use. They are not recommended for use in aggressive environments with temperatures above +50 °C and below -40 °C.

Some deviation from the norm is acceptable, but if the products are exposed to constant extreme temperatures, then cracks and partial damage to the integrity of the reinforced concrete products will appear. There are specific types of buildings for which purlins are used:

for heated buildings with a roof slope of 5°;
for rooms without heating with a flat roof, equipped with lightweight fences;
for residential buildings, the roof of which is mounted directly on the lintels.

Reinforced concrete beams are capable of withstanding earthquakes with an amplitude of no more than 7 points and are capable of being in gas environment conditions no higher than the average level.

Prices, where to buy

When choosing a supplier of building materials, the main influencing factors are product cost and quality. Of course, the best balance of these parameters will be with a company that produces the products it sells.

StroyPromZhBI LLC is engaged in the sale of reinforced concrete products of its own production. Our plant in the Tula region began operations in 2009, since then we have achieved significant success and do not stop developing.

The price for our reinforced concrete purlins is so attractive that many organizations working in other regions (Moscow, Kaluga, Yaroslavl, Bryansk and others) prefer to buy them from us, even taking into account transportation costs. Contact us to discuss deliveries to your region.

Purpose of structures

So, they are used for the construction of objects, as well as other objects intended for residential and even industrial purposes, made of a metal frame. In a steel frame building, it usually serves as a convenient fastener for all fencing structures, roofing, and wall frame structures. It is also considered a reinforcing object for the rafter structure, which can bear almost all weather loads. They are usually capable of equally distributing almost all the loads from the roof structure to the main load-bearing structures, as well as the truss structures of the structure, these can be: frames, columns, walls, trusses.

Basic construction scheme

The scheme of any construction with purlin fastening consists of:

rafters;
beams;
Mauerlat;
ridge beam;
run;
strut;
puffs;
props.

Each run is treated with an anti-corrosion agent, thereby increasing the overall service life of the frame structure. During development, the steel material is subjected to a hot-dip galvanizing process, after which fine powder is applied. In this case, they are considered components of the double-sided frame of the structure, and special safety requirements may be imposed on them.

Manufacturing of reinforced concrete purlins in St. Petersburg

Dorjbi company produces reinforced concrete products for industrial construction. We offer construction organizations and individuals T-section purlins series 1.225-2.

Our catalog contains the following types:

P40-33;
P40-30;
P30-63 A-IV;
P30-63;
P30-60 A-IV;
P30-60.

The products are made of high-strength concrete M200 and M400, steel A-3, A-4, BP-2 is used for reinforcement. The purlins have a height of 440 mm, a width of 420 mm, and a length of 2980, 3280, 5980, 6280 mm. We produce reinforced concrete purlins to impart strength to buildings and structures, increase reliability and durability. To do this, you need to choose the right type of product. Our managers will help, advise, and accept your application. All products are manufactured in accordance with the requirements of GOST and TU; at the request of the customer, we will produce non-standard products. We strictly comply with the terms of the contract, we will produce and deliver purlins on time.