Reinforced concrete runs - everything you need to know about

20-08-2018

Building

The run is a part of the construction of precast concrete or brick structures, installed in a horizontal position and based on the supporting beams or trusses. The elements themselves also have impressive strength and are used as a support for floor slabs or flooring. There is a separate GOST for reinforced concrete runs, which regulates all the requirements that must be met by the product.

In the photo - the girders are based on the beams and perform the supporting function when installing floors and roofing

The main features of this type of construction

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

Strength	The design load of the products must be at least 4,000 kgf / m, which allows the use of elements in the construction of load-bearing walls.
Types of sections	There are two types of sections: rectangular and tee. In construction reference books one can also find Z-shaped and C-shaped girders, but they represent a metal profile and are not used as elements of supporting structures.
Production material	The material used is heavy concrete M250, and for structures 6 meters long or more, an even stronger M350 must be used.
Reinforcement	There are two main types of reinforcement: non-stressed, consisting of a spatial steel reinforcement cage, and stress, which is a pre-stressed reinforcing bars and a spatial framework.
Installation Features	It is important to remember that the weight of the products is very large and it is unlikely that it will be possible to do the installation with your own hands - you need lifting equipment. It is for this reason that the runs are not often used in private buildings.

Note! Do not confuse runs with jumpers. Jumpers are used for similar purposes, but their sizes are much smaller, in addition, they are not designed for heavy loads and can not be used in systems of supporting structures. Runs are suitable for any purpose: from reinforcement of openings (especially large ones) to creation of additional strength in places of the supports of reinforced concrete slabs.

Runs are much larger and more massive than jumpers

Types of runs

The separation of products made by the type of section. There are two main options, each of which we consider in more detail.

Elements with a rectangular section

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

Each of the parameters is indicated by a Latin symbol, thanks to which all basic parameters can be easily identified by marking.

We note the main features of this product group:

The use of heavy grades of concrete provides high strength, which allows the use of runs on any industrial sites.
There are two main options for designs: solid and lattice. The second option has a smaller mass due to the presence of voids and is most often used for mounting on trusses, they are located in 6 meter increments.
Pre-stressed reinforcing bars are used to increase strength.. In ordinary products used conventional frame.

You should not forget that the dimensions of reinforced concrete girders are written in decimeters, the letter "T" means that heavy concrete was used for the manufacture. If there are additional factors, they are also marked in the labeling. Marking instructions are the same for all manufacturers, so it’s important to know the general rules.

Example. Let us consider the run variant 44.3.5-4Т, marking means that the element is 44 decimeter, thickness is 3, and height is 5 Dm, the design load is 4 tons per meter, heavy concrete was used in the manufacture.

Elements with T-section

Such elements are especially often used in areas with high seismic activity, as they are able to withstand shocks up to 7 points.

For this group of products we can say the following:

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

You can create a very sturdy construction with the help of tee runs.

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

Remember! Whichever option you choose, it is important that it be made in accordance with GOST. Since it will be subject to significant stress, the quality must be at the highest level.

Conclusion

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