Dimensions of beams. Weight and designation of beams

There are many types of beams. They are divided by purpose: foundation, for floors, supporting; By material: steel, wood, reinforced concrete. In most cases, all information lies in the designation of the element, but it is clear only to specialists. To find out what is behind the abbreviations in the titles, how to know the size of the beams, determine the weight, the desired type, consider the main categories of construction products.

General concept

The beam is a horizontal structural element of the structural system, having from one to several points of support. It can overlap as one (split), and several spans (continuous). According to the material, the beams are divided into:

• Metal (steel).
• Wooden.
• Reinforced concrete.

They are used in construction as load-bearing structures working on bending, and in mechanical engineering (for example, as an element of a bridge crane).

Metal beams

The largest group. Classification, according to which it is possible to get a general idea of metal beams:

1. According to the working scheme:

1.1. Single-span (split).

1.2. Multiple-span (continuous).

1.3. Cantilever (with one support in the form of pinching).

Cutting is the most convenient for manufacturing and installation in comparison with multi-span. Unshielded beams are advisable to be installed on reliable supports, where there is no danger of uneven subsidence.

2. By type of section :

2.1. Rolling (one-T, I, through).

2.2. Composite: welded, bolted, riveted.

The most common in the application are I-beam beams - they are simple in production and are universal in use. Further, we will consider them.

Parameters of the I-beam

Metal products are distinguished by their reliability and high technical performance. I-beams are no exception. They are referred to the category of long products, production is carried out according to technical specifications. In turn, the specifications are based on the requirements to which the beam must conform: GOST 535-2005 "Graded and shaped rolled steel of ordinary quality carbon" they are regulated.

By the form of the beam profile can be:

1) With parallel shelves:

1.1) Normal (B).

1.2) With a wide shelf (W).

1.3) Colonies (K).

In the product name, the profile type is always encrypted. For example, the beam size 20b1 implies the following: height 20 cm, B - normal, width 100 mm (10 cm).

2) With a slope of internal faces:

2.1) Ordinary - 6-12% of the slope.

2.2) Special: M - for hanging ways of cranes and other equipment (≤12%).

2.3) C - for reinforcement of shafts (≤ 16%)

I-beam: dimensions and weight

These values depend on each other, as well as on the type of steel used for production. To determine them, you need to use look-up tables. Where can I get them?

There are grades based on GOST 8239-89, 19425-74, 26020-83. By type of profile, select the appropriate table, find in it the necessary dimensions of the beams, for each specific case, the weight of the product is given per 1 running meter. This value is considered to be a reference, used in calculations, but in practice it may slightly differ from the actual (if the production is conducted according to the specification).

For example: beam 20b1. Dimensions according to the assortment: height - 200 mm, width - 100 mm, wall thickness - 5.6 mm, shelf size - 8.5 mm, radius of curvature of the inner edge - 12 mm.

The I-beam, whose dimensions and weights are indicated in the table, is the standard for this species. When purchasing products, the manufacturer must provide information about the actual parameters of the elements to the customer.

Wooden beams

Most often used in the construction of houses as elements of overlapping floors, floors, the finishing layer of the ceiling, as part of the construction of trusses, rafters for the installation of roofs. The element is a bar of rectangular section with parameters for height - 140-250 mm, width - 50-160 mm. The length can be from 2 to 5 meters (without regard to the amount of support).

The composition of the bar can be either whole or glued (multi-layered). For production, coniferous trees are used because they have good elasticity and work on bending, which is important for horizontal bearing elements.

Dimensions of wooden beams depend on the size of the load on the future overlap, on the type of filling the volume of the structural element (heaters, rolls), from the size of the span. All these parameters are regulated by GOST 4981-87 "Wooden floor beams".

Features of the installation

Before use, wooden elements must be treated with antiseptic compositions that prevent rotting, damage by microorganisms and rodents, and also increase the fire resistance of the beams.

Elements of ceilings are installed in specially constructed nests during the management of masonry or by cutting into the upper crown of the structure of walls from various wooden materials. Installation is made from the extreme to the central bars. The support end should not be shorter than 15 cm.

• When laying the timber on the external walls, the free ends are cut down at 60 ^° , treated with antiseptics and protected with a ruberoid or roofing felt.
• When embedding the beams in the masonry, the end of the bar must be dried and treated with bitumen to prevent its decay.
• Fill the space niche in the wall with a heater. You can arrange a wooden box.
• In thick walls, it is necessary to leave a ventilation duct, through which moisture will be removed from the free end.
• With thin walls (up to two bricks) the space in the niches can be filled with cement mortar.
• On the inner walls of the beams are laid on the roofing layer.

The beam can be replaced with a log, the diameter of which corresponds to the height of the rectangular section of the element. This is economical in terms of material purchase, but it is worth remembering that fixing should be done in a special way using anchors with walling.

Reinforced concrete beams

Widely used in large-scale construction of residential and public buildings.

Classify the beam by several parameters, the main one can be considered the division by purpose and the type of section simultaneously:

• Fundamental . They are used for the device of the foundations of industrial objects and apartment houses in zones of increased seismic activity. They can have a T-shaped profile or a section in the form of a trapezoid.
• Rafting gable or single-deck systems serve for roof overlapping in production and farming complexes. They have ledges for fastening rails.
• Rectangular beams with different configurations (tie bars, I-beams, L-shaped and T-shaped profiles) serve to cover the spans of facades, floors up to 18 meters.

The dimensions of the beams depend on their purpose and have different parameters. For example, rafters have a length of up to 24 m, and ordinary floor elements can be supported on a span of up to 18 m. The remaining parameters are determined individually for each product.

The dimensions of the floor beams can be found in the catalogs of the State Standard or from specific manufacturers, since they may differ. GOST 20372-90 "Trusses and rafter reinforced concrete" defines the basic requirements for products, materials and reinforcement of the structure, on this basis the enterprises create a technical specification.

Basic calculation

All the building structures in Soviet times were divided into series. There are unified catalogs of concrete products, in which all types and sizes of blocks, beams, plates produced in factories of different regions are given. In the tabular reports, the dimensions of all parts of the elements, their calculated mass, are presented. This literature can still be used as a reference in the design of buildings, but engineers necessarily compare the data of concrete products with the availability of such products from modern suppliers.

There are several principles for calculating reinforced concrete beams. The dimensions must correspond to the following parameters:

1. The height is at least 5% of the length of the span to be overlapped.
2. The width of the beam is determined by the ratio 5: 7 (width to height).
3. Reinforcement of the product is carried out according to the scheme: 2 bars from below and from above (resistance to deflection). For the frame take the steel rods with a diameter of 12-14 mm.

In this way, you can determine the required beam dimensions for a particular section.