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

1. Collection of loads

Before starting the calculation of a steel beam, it is necessary to collect the load acting on the metal beam. Depending on the duration of the action, the load is 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 geographical location building);
special load (seismic, explosive, etc. within this calculator not taken into account);

The loads on the beam are divided into two types: design and standard. Design loads are used to calculate the beam for strength and stability (1 limit state). The normative loads are established by the norms and are used to calculate the beam for deflection (limit state 2). Design loads are determined by multiplying the standard load by the reliability load factor. Within the framework of this calculator, the design load is applied when determining the deflection of the beam to the margin.

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, you need to multiply the surface load by the step of the beams (the so-called cargo lane).

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

2. Plotting

Next, the diagram of the moments, the transverse force is plotted. The diagram depends on the beam loading scheme, the type of beam support. The plot is built according to the rules of structural mechanics. For the most commonly 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 strength (1st limit state) and deflection (2nd limit state) are calculated. In order to select a beam for strength, it is necessary to find the required moment of inertia Wtr and select a suitable metal profile from the assortment table. The vertical limit deflection fult is taken according to Table 19 of SNiP 2.01.07-85* (Loads and impacts). Paragraph 2.a depending on the span. For example, the maximum deflection is fult=L/200 with a span of L=6m. means that the calculator will select the section of the rolled profile (an I-beam, a 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 according to the deflection, the required moment of inertia Itr is found, which is obtained from the formula for finding the ultimate deflection. And also from the assortment table, a suitable metal profile is selected.

4. Selection of a metal beam from the assortment table

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

In the construction of residential buildings and other structures, everyone is faced with the need for proper calculation and installation of the ceiling. The cover 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 takes all the loads coming from furniture, people, equipment and the ceiling itself and transfers them either to the walls or to the columns (depending on the type of structure).

Types of floors

According to the purpose of the overlap can be divided into:

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

Depending on the design features their overlaps can be divided into tiled and beamed:

Tiled floors are most often mounted in large-sized stone houses using reinforced concrete slabs.
Beam ceilings 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 of the channel for overlapping as a supporting base. It is they who perceive the entire load falling on the floors of the second floor. If U-shaped rental 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 section modulus in this direction is several times greater than the value of the moment in the opposite direction
the laying scheme is as follows - from the middle of the overlap, the profile must be turned in the opposite direction, since the center of gravity of the channel does not belong to its wall

Such a laying scheme is necessary to compensate for tangential stresses. It should be remembered that the channels for overlapping are subject to bending stresses.

Calculation of the bending of the channel for floors

We will calculate the channel for overlapping based on the following conditions. There is a room with a size of 6x8 m. The step of the whips of the floor channel is p \u003d 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. Regulatory load per square meter will be 540 kg/m2, and the calculated one is 624 kg/m2 (according to SNiP, taking into account the reliability factors for each component of the load). Let the floor 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 on one running meter channel will be (normative 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 section of the channel 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

Let us determine the required section modulus by the expression:

Wtr = Мр/(γ∙Ry)∙1000, where

Ry = 240 MPa - resistance of steel C245, calculated
γ = 1 – coefficient of working conditions

Then Wtr = 60/(1∙240)∙1000 = 250 cm3

Section selection and channel stiffness test

According to the reference book (see GOST 8240-97 or GOST 8278-83), we select the channel profile, 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 (lash deflection).

Test of strength:

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

Stiffness test, channel bending where the relative deflection f/L must be less than 1/150 and is determined by the expression:

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

The rigidity condition is provided. Therefore, this channel can be used for overlapping according to the described scheme. You can reduce the channel number if the whips are laid with a smaller step.

It provides stability not only with a reliable foundation, but also with a system of solid floors. They are also necessary in any one in order to equip a basement or garage under it, and build a roof over it. Overlapping structures take up to 20 percent or more of all construction costs. Therefore, their installation is a very serious and responsible matter.

Installation of interfloor ceilings in a house from a bar

Interfloor;
Basement;
Basement.

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 an entrance hall, a dining room.

Scheme for arranging concrete floors

In addition, they, together with the foundation, must provide stable rigidity of the hull made of any material: wood, brick, aerated concrete. Some rise above ground level. If it is heated, then the structure that overlaps it is practically no different from interfloor devices.

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

Types of floors by material

Wooden;
Reinforced concrete;
Metal.

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 device:

Some overlapping systems are held on horizontal beams. For the installation of other beams, they are not required, the plates of the required dimensions ordered at the factory are sufficient. They are stacked in the house using lifting equipment. And monolithic ceilings are poured directly on the construction site. Prefabricated-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 their lower side there are ribs that make up rectangles, together they resemble the surface of a waffle. In private housing construction, they are used very rarely. A hipped ceiling is a flat slab bordered with ribs. Usually it alone is enough for the ceiling of the entire room, under the size of which it is made.

Arched devices are necessary when it is required to block the curly spans of houses. Aerated concrete slabs are used in private one and two-story houses. The overlapping structure made of it has very good sound insulation, retains heat for a long time, therefore, in interfloor partitions, additional insulation may be superfluous. The material is light, odorless, it does not emit any fumes or harmful substances.

Its fire resistance is also very high. But he needs effective waterproofing, as 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. For monolithic structures, a variety of non-removable formwork is used. Sometimes their main part is hollow concrete panels, and the ceiling of a semicircular bay window is aerated concrete slabs, which are easy to give any shape and thickness with a hand saw.

A variant of the design of the ceiling of aerated concrete blocks

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

Cover requirements

All interfloor devices are subject to general requirements:

Strength - the ability to withstand the weight of all elements of the building.
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.
The service life corresponding approximately to the time of use of the entire building.

Wooden beams

In the construction of country houses, larch or pine solid beams are widespread. They are used for the 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, determining it at the end by the density of growth rings in a wooden log. In Rus', huts have long been built with a more durable side of the round timber outward.

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

Scheme of the design of wooden floors from logs

Very convenient not only for filing the ceiling, laying insulating materials and subflooring, but also for the installation of all communications. The niches in the I-beam seem to be specially designed for hidden laying of water pipes, gas pipelines and electrical wires.

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 the load-bearing beams. Since the wood is not heavy, gas-block walls can withstand its weight. Installation of the overlapping structure is possible without the involvement of complex technical means. And it will cost the developer relatively inexpensively.

Laying wooden beams

Builders are aware of the shortcomings of wood and try to minimize them. Before installing the ceiling, all wooden parts are treated with antiseptics that prevent rotting and insect damage. The points of contact between beams made of timber 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. Next, you will need simple materials that provide insulation, and you can’t do without the following tools:

The process of laying wooden floors from beams and boards

saws;
hammer;
mounting knife;
roulettes;
construction stapler.

The beams are reinforced with anchors in the niches of the brick wall. But before laying, they make an oblique cut at the ends of the timber and impregnate it with an antiseptic. The area of \u200b\u200bcontact between wood and brick is tarred, wrapped with roofing material. The ends of the supports in the niches must be closed tightly. Slots can be eliminated with mounting foam.

Then, floor logs are laid on the load-bearing beams, and rubber pads are placed under them to reduce the oscillation of the structure. From below perform filing for the ceiling. Attic and basement overlapping devices need insulation. Interfloor partitions can do without it, 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 in a summer cottage, other buildings and structures, everyone is faced with the need for the correct calculation and installation of the ceiling. The ceiling 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 takes all the 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 ceilings and channel for ceiling from APEX metal

By purpose, the floors can be divided into: basement, interfloor and attic. The first 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 mounted in large stone houses using reinforced concrete slabs. Beam ceilings 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 section modulus in this direction is several times greater 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 must be turned in the opposite direction, since the center of gravity of the channel does not belong to its wall.

Therefore, such a laying scheme is necessary to compensate for tangential stresses. It should be remembered that the channels for overlapping are subject to bending stresses.

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

We will calculate the channel for overlapping based on the following conditions. There is a room with a size of 6x8 m. The step of the whips of the floor 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 normative load per square meter will be 540 kg/m2, and the calculated load is 624 kg/m2 (according to SNiP, taking into account the reliability factors for each component of the load). Let the floor 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 (normative 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 section of the channel 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

Let us determine the required section modulus by the expression:

Ry \u003d 240 MPa - resistance of steel C245, calculated
γ=1 – coefficient of working conditions

Channel bending calculation - section selection and stiffness test

According to the reference book (GOST), we select the channel profile, 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 (lash deflection).

Test of strength:

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

Stiffness test, channel bending where the relative deflection f/L must be less than 1/150 and is determined by the expression:

The rigidity condition is provided. Therefore, this channel can be used for overlapping according to the described scheme. You can reduce the channel number if the whips are laid with a smaller step.

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