The lintel as a structure above the opening, perceiving loads from overlying walls and ceilings, appeared a very long time ago, as soon as people began to build stone public buildings and housing.
A bit of history
Most of the lintels above the openings were arched, as the upper semicircular contour of the window somewhat weakened the load. They were made from large stones. These stones were carefully hewn, adjusted to each other, such work required a significant investment of time and effort.
The construction of buildings went on for a long time, the slightest inaccuracy in the installation of lintel stones, especially the central, castle ones, could lead to distortion and destruction of the structure. But when the magnificent building was built, its life was calculated in centuries.
With the advent of brick as a building material, lintels were still arched at first. But it was already easier to work, since the bricks were of the same size, and when arranging the jumper, it was possible to make seams of different thicknesses, due to which the desired opening radius was achieved
Slab reinforced concrete lintels
When people built houses from wood, a lintel over a window orthe doorway was a thick log overlapping the window with plenty of room.
With the development of science, technology, the discovery of new technologies in construction, in particular with the introduction of reinforced concrete, reinforced concrete lintels appeared. These jumpers have a rectangular section, their width is not more than 250 mm. They are intended for blocking openings in the brick walls of residential and public buildings. These products are produced in series 1.038.1- 1.
The photo above shows bar lintels. In addition to bar, slab, beam, facade lintels and girders are produced. All of them are fireproof structures.
Jumper markings
All jumper names consist of five groups of numbers and letters. For example, jumper 2 PB 19-3-p.
- 2 means cross-section number;
- PB stands for the name - bar lintel;
- 19 - product length in decimeters;
- 3 - design load in kN/m (kgf/m);
- p means mounting loops.
The first digits in the marking, from 1 to 5, indicate the dimensions of the cross-section of the product.
Those bar lintels, in the name of which the first digit is 1, with transverse dimensions of 120x65 (height) mm, can block openings in non-bearing brick partitions 120 mm thick.
If the first number is 2, then the transverse dimensions will be 120x140 (height) mm. These lintels can withstand loads up to 400 kgf/m and are used in self-supporting walls. If the first number is 3, then the transverse dimensions will be 120x220(height) mm. These jumpers are reinforced, they withstand the load from the overlap.
Each lintel has a certain depth of bearing on the wall, depending on its bearing capacity. If the load on the jumper does not exceed 400 kgf/m, then the support depth can be 120 mm, if the load is more than 400 kgf/m, then the support depth will already be from 170 mm to 230 mm.
In order to choose the right jumper, you need to know the width of the opening to be covered, the thickness of the wall where the opening is located, and whether the ceiling rests on it.
Depending on the thickness of the wall, two or three bar lintels are laid above the opening, and a reinforced one is laid on the side of the ceiling.
Features of transportation and installation
Sometimes, especially before transportation, it is necessary to calculate the volume of bar lintels. When calculating, it should be taken into account that the transport stack should have a height of no more than 2 m, and each jumper should be laid on two wooden spacers.. The top plane of the lintel should be flush with the top of the masonry.
The lintels are installed on a layer of M100 cement-sand mortar. The lintel, located at the outer edge of the wall, is installed 65 mm below the others, forming a quarter, necessary when installing windows so that the wind does not blow into them.
