Channel - use and load. Calculation of a metal beam online (calculator) Which channel to use for an overlap of 5 meters

1. Collecting loads

Before starting to calculate the steel beam, it is necessary to collect the load acting on the metal beam. Depending on the duration of the action, the loads are divided into permanent and temporary.

own weight of a metal beam;
own weight of the floor, etc .;

long-term load (payload, taken depending on the purpose of the building);
short-term load (snow load, taken depending on geographic location building);
special load (seismic, explosive, etc. Within of this calculator not taken into account);

Beam loads are divided into two types: calculated and standard. Design loads are used to calculate the strength and stability of the beam (1 limit state). The standard loads are established by the norms and are used to calculate the deflection of the beam (2nd limit state). Design loads are determined by multiplying the standard load by the load factor for reliability. In this calculator, the design load is used to determine the deflection of a beam to stock.

After collecting the surface load on the floor, measured in kg / m2, it is necessary to calculate how much of this surface load the beam takes on. To do this, multiply the surface load by the spacing of the beams (the so-called load strip).

For example: We calculated that the total load is Qsurface = 500kg / m2, and the spacing of the beams is 2.5m. Then the distributed load on the metal beam will be: Qdist. = 500kg / m2 * 2.5m = 1250kg / m2. This load is entered into the calculator

2. Construction of diagrams

Next, the diagrams of moments, transverse forces are plotted. The diagram depends on the loading scheme of the beam, the type of support of the beam. The diagram is built according to the rules of structural mechanics. For the most frequently used loading and support schemes, there are ready-made tables with derived formulas for diagrams and deflections.

3. Calculation of strength and deflection

After plotting the diagrams, the calculation is made for strength (1 limit state) and deflection (2 limit state). In order to select a beam in terms of strength, it is necessary to find the required moment of inertia Wtr and select a suitable metal profile from the assortment table. The vertical limiting deflection fult is taken according to table 19 from SNiP 2.01.07-85 * (Loads and actions). Point 2.a depending on the span. For example, the ultimate deflection fult = L / 200 with a span of L = 6m. means that the calculator will select the section of the rolled profile (I-beam, channel or two channels in a box), the maximum deflection of which will not exceed fult = 6m / 200 = 0.03m = 30mm. To select a metal profile by deflection, find the required moment of inertia Itr, which is obtained from the formula for finding the ultimate deflection. And also a suitable metal profile is selected from the assortment table.

4. Selection of a metal beam from the assortment table

Of the two selection results (1 and 2 limiting state), a metal profile with a large section number is selected.

During the construction of residential buildings and other structures, everyone is faced with the need for correct calculation and installation of floors. The overlap is horizontal structure located inside the building, which divides it into adjacent rooms vertically (floors, attic, etc.). In addition, this structure is load-bearing, since it perceives all loads coming from furniture, people, equipment and the floor itself and transfers them either to the walls or to the columns (depending on the type of structure).

Floor types

Overlapping can be divided into:

basement - separate the first floor of the building from basement floor or basement
interfloor - aimed at dividing the floors of a building
attic. First. From the name of the second type it follows that they are. The latter separate the attic space from the residential building.

Depending on the design features they can be divided into slab and beam ceilings:

Tiled floors are most often mounted in large-sized stone houses using reinforced concrete slabs.
Beam floors used in the construction of low-rise residential buildings. For their installation, metal or wooden beams can be used.

Floor channel

Let us consider in more detail the structures from the channel for the ceiling as a load-bearing base. They are the ones who take all the load on the floors of the second floor. If U-shaped steel is used for the installation of the ceiling, then the following points must be taken into account:

the channel must be laid vertically, since the moment of resistance of the section in this direction is several times higher than the value of the moment in the opposite direction
the laying scheme is as follows - from the middle of the overlap, the profile should be turned in the opposite direction, since the center of gravity of the channel does not belong to its wall

This arrangement is necessary to compensate for tangential stresses. It should be remembered that floor channels are subject to bending stresses.

Calculation of the bending of the channel for floors

Let's calculate the channel for the overlap based on the following conditions. There is a room with a size of 6x8 m. The pitch of the whips of the ceiling channel is p = 2 m. It is logical to assume that the channel should be laid along a short wall, which will reduce the maximum bending moment acting on it. Standard load for one square meter will be 540 kg / m2, and the calculated one - 624 kg / m2 (according to SNiP, taking into account the safety factors for each component of the load). Let the ceiling channel on each side rest on a wall 150 mm long. Then the working length of the channel will be:

L = l + 2/3 ∙ lop ∙ 2 = 6 + 2/3 ∙ 0.15 ∙ 2 = 6.2 m

Load for one running meter the channel will be (standard and calculated, respectively):

qн = 540 ∙ р = 540 ∙ 2 = 1080 kg / m = 10.8 kN
qр = 540 ∙ р = 624 ∙ 2 = 1248 kg / m = 12.48 kN

The maximum moment in the channel section will be equal (for the standard and design load):

Мн = qн ∙ L2 / 8 = 10.8 ∙ 6.22 / 8 = 51.9 kN ∙ m
Мр = qр ∙ L2 / 8 = 12.48 ∙ 6.22 / 8 = 60 kN ∙ m

Determine the required moment of resistance of the section by the expression:

Wtr = Мр / (γ ∙ Ry) ∙ 1000, where

Ry = 240 MPa - resistance of steel С245, calculated
γ = 1 - coefficient of working conditions

Then Wtr = 60 / (1 ∙ 240) ∙ 1000 = 250 cm3

Selection of the section and check for the stiffness of the channel

According to the reference book (see GOST 8240-97 or GOST 8278-83), we select the profile of the channel, which has a moment of resistance greater than the calculated one. In this case, a 27P channel is suitable, Wx = 310 cm3, Ix = 4180 cm4. Next, it is necessary to check the strength and bending stiffness of the channel (whip deflection).

Test of strength:

σ = Мр / (γ ∙ Wx) ∙ 1000 = 60 ∙ 1000 / (1 ∙ 310) = 193 MPa< Ry = 240 МПа, что подтверждает условие прочности

Check for stiffness, channel bending where the relative deflection f / L should be less than 1/150 and is determined by the expression:

f / L = Mn ∙ L / (10 ∙ Е ∙ Ix) = 60 ∙ 103 ∙ 620 / (10 ∙ 2.1 ∙ 105 ∙ 4180) = 1/236<1/150

The stiffness condition is ensured. Therefore, this channel can be used for overlapping according to the described scheme. It is possible to decrease the channel number if the whips are laid with a smaller pitch.

Provides stability not only with a reliable foundation, but also with a system of solid floors. They are also necessary in anyone in order to equip a basement or garage under it, and erect a roof above it. Overlapping structures account for up to 20 percent or more of all construction costs. Therefore, their installation is a very serious and responsible business.

Installation of interfloor ceilings in a house from a bar

Interfloor;
Basement;
Basements.

The greatest load in the house falls on the basement and basement. Their horizontal partitions must withstand the weight of kitchen equipment, as well as the weight of the internal walls dividing the first floor into the hallway and dining room.

Scheme for arranging concrete floor slabs

In addition, they, together with the foundation, must ensure the stable rigidity of the body made of any material: wood, brick, aerated concrete. For some, it rises above ground level. If it is heated, then the structure covering it is practically no different from the interfloor devices.

The horizontal partition, designed to separate the floors, has a relatively small load: its own weight, furniture, residents. It is important that it has good sound insulation for a comfortable stay. or this problem is not so acute. For them, moisture insulation and warming are important.

Floor types by material

Wooden;
Reinforced concrete;
Metallic.

However, in some cases, when building a house, you can do without them, because the following types of floors are used according to the structural design:

Some ceiling systems are supported by horizontal beams. For the installation of other beams, they are not required, the slabs of the required dimensions ordered from the factory are sufficient. Stacked in the house using lifting equipment. And monolithic floors are poured right on the construction site. Precast monolithic devices between floors are a combination of beam supports and a concrete monolith.

Coffered horizontal structures are usually used for arranging the ceiling. On the underside of them there are ribs that make up rectangles, in the aggregate, they resemble the surface of a waffle. In private housing construction they are used very rarely. And the hipped roof is a flat slab bordered by ribs. Usually, it alone is enough for the ceiling of the entire room, to the size of which it is made.

Arched devices are necessary when it is required to block the curly spans of houses. In private one and two-story houses, aerated concrete slabs are used. The overlapping structure made of it has very good sound insulation, retains heat for a long time, therefore, additional insulation in the interfloor partitions may be superfluous. The material is lightweight, odorless, no fumes or harmful substances emanate from it.

Its fire resistance is also very high. But he needs effective waterproofing, since he absorbs moisture from the environment well.

In construction practice, partitions are used with a mixture of various materials. Wooden beams are reinforced with metal to increase strength. Monolithic structures use a variety of non-removable formwork. Sometimes their main part is hollow concrete panels, and the ceiling of a semicircular bay window is aerated concrete slabs, which can be easily given any shape and thickness using a hand saw.

Variant of floor construction from aerated concrete blocks

Such a variety of materials expands the architectural possibilities of overlapping devices, their sound insulation and insulation.

Floor requirements

All interfloor devices have general requirements:

Strength is the ability to support the weight of all building elements.
Rigidity, allowing not to bend under the weight of its own weight, heavy things on the floor.
Effective thermal insulation and sound insulation of floors.
Fire resistance, which is characterized by resistance to fire for some time.
A service life that corresponds approximately to the use time of the entire building.

Wooden beams

In the construction of country houses, solid larch or pine beams are widespread. They are used for installation of ceilings with a width of 5 m. And for large spans, glued ones are used, the strength of which is much higher.

Installation of floors from wooden beams

Rounded timber is a wonderful building material for floors. It is laid with the north side down, defining it at the end by the density of annual rings in a wooden log. In Russia, for a long time, huts were built with a more solid side of round timber outward.

A wooden I-beam has high strength. Its profile is the letter "H", glued in the factory from three parts. Some craftsmen collect it in their home workshop or in the country. Interfloor partitions with their use provide effective insulation and excellent sound insulation.

Diagram of the construction of wooden floors from logs

They are very convenient not only for filing the ceiling, laying insulating materials and sub-flooring, but also for installing all communications. Niches in the I-beam seem to be specially designed for hidden laying of water supply pipes, gas pipelines and electrical lines.

Wooden beams are used in almost any low-rise dwelling: wooden, block. But most of all they are suitable for buildings made of aerated concrete blocks. This material is porous, inferior in strength to all others and does not withstand the point load of load-bearing beams. Since the wood is not heavy, gas-block walls can quite withstand its weight. Installation of the overlapping structure is possible without the involvement of complex technical means. And it will cost the developer relatively inexpensive.

Laying wooden beams

Builders are aware of the disadvantages of wood and try to keep them to a minimum. Before installing the floor, all wooden parts are treated with antiseptics to prevent rotting, insect damage. The places of contact of timber beams with bricks, concrete slabs and aerated concrete blocks are insulated with various materials.

And in order to increase fire safety, wood is treated with solutions that do not allow it to flare up immediately when an open fire appears.

Installation of interfloor structures begins with pre-prepared load-bearing beams. They are laid parallel to the short wall of the dwelling. The laying step depends on the width of the span, but on average it is 1 m.Further, you will need simple materials that provide insulation, and you cannot do without the following tools:

The process of installing timber beams and planks

saws;
hammer;
assembly knife;
roulette;
construction stapler.

The beams are reinforced with anchors in the niches of the brick wall. But before laying, an oblique cut is made at the ends of the timber and impregnated with an antiseptic. The area of contact of wood with brick is smeared, wrapped with roofing material. The ends of the supports in the niches should be tightly closed. Crevices can be filled with polyurethane foam.

Then logs for the floor are laid on the supporting beams, and rubber gaskets are placed under them, in order to reduce the vibration of the structure. From below, a ceiling filing is performed. Attic and basement ceiling devices require insulation. Interfloor partitions can be dispensed with, but good sound insulation is required.

How to choose the right channel for floors, knowing its bending calculations

During the construction of a residential building, a garage, summer houses at a summer cottage, other buildings and structures, everyone is faced with the need for correct calculation and installation of the floor. The slab is a horizontal structure located inside the building, which divides it into adjacent rooms vertically (floors, attic, etc.). In addition, this structure is load-bearing, because it perceives all loads coming from furniture, people, equipment and the floor itself and transfers them either to the walls or to the columns (depending on the type of structure).

Types of slabs and channel for slabs from APEX metal

By purpose, the floors can be divided into: basement, interfloor and attic. The first ones separate the first floor of the building from the basement or basement. From the name of the second type, it follows that they are aimed at dividing the floors of the building among themselves. The latter separate the attic space from the residential building.

Depending on the design features of the floor, they can be divided into slab and beam. Tiled floors are most often installed in large-sized stone houses using reinforced concrete slabs. Beam floors are most often used in the construction of low-rise residential buildings. For their installation, metal or wooden beams and filler material can be used.

firstly, it must be laid vertically, since the moment of resistance of the section in this direction is several times higher than the value of the moment in the opposite direction;
secondly, the scheme of their laying is as follows - from the middle of the overlap, the profile should be turned in the opposite direction, since the center of gravity of the channel does not belong to its wall.

Therefore, this arrangement is necessary to compensate for tangential stresses. It should be remembered that floor channels are subject to bending stresses.

Calculation of the bending of a channel from APEX metal used for floors

Let's calculate the channel for the overlap based on the following conditions. There is a room with a size of 6x8 m. The pitch of the whips of the ceiling channel is p = 2 m. It is logical to assume that the channel should be laid along a short wall, which will reduce the maximum bending moment acting on it. The standard load per square meter will be 540 kg / m2, and the calculated one - 624 kg / m2 (according to SNiP, taking into account the safety factors for each component of the load). Let the ceiling channel on each side rest on a wall 150 mm long. Then the working length of the channel will be:

The load per linear meter of the channel will be (standard and calculated, respectively):

qн = 540 ∙ р = 540 ∙ 2 = 1080 kg / m = 10.8 kN
qр = 540 ∙ р = 624 ∙ 2 = 1248 kg / m = 12.48 kN

The maximum moment in the channel section will be equal (for the standard and design load):

Мн = qн ∙ L2 / 8 = 10.8 ∙ 6.22 / 8 = 51.9 kN ∙ m
Мр = qр ∙ L2 / 8 = 12.48 ∙ 6.22 / 8 = 60 kN ∙ m

Determine the required moment of resistance of the section by the expression:

Ry = 240 MPa - resistance of steel С245, calculated
γ = 1 - coefficient of working conditions

Calculation of channel bending - section selection and rigidity check

According to the reference book (GOST), we select the profile of the channel, which has a moment of resistance greater than the calculated one. In this case, a 27P channel is suitable, Wx = 310 cm3, Ix = 4180 cm4. Next, it is necessary to check the strength and bending stiffness of the channel (whip deflection).

Test of strength:

σ = Мр / (γ ∙ Wx) ∙ 1000 = 60 ∙ 1000 / (1 ∙ 310) = 193 MPa

Check for stiffness, channel bending where the relative deflection f / L should be less than 1/150 and is determined by the expression:

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