Construction of interfloor ceilings in a private house. Calculation of a metal beam online (calculator) Which channel to use for overlapping

Let's start with what is overlap?

An overlap is a structure that separates adjacent rooms in height.

talking plain language, overlap is a structure for the formation of floors, both for separating the living space from the attic and basement, and for separating the living quarters. They distinguish between interfloor, basement, basement and the magnitude of the withstand load (it is determined by the type of beams and the distance between the floor beams), as well as the sheathing of the beams.

Reinforcing cage for a monolithic floor slab

Cover requirements

The structure must have the necessary strength in order to withstand not only the load of its own weight, but also additional - such as the weight of people, furniture, equipment. The value of the expected load per square meter of flooring is determined depending on how the room is used.

The corresponding calculation is performed. Here are the loads:

for the basement and interfloor - at least 210 kg of load per sq. m of floor area.

Based on this, it is determined which timber to use and how to lay it.

load on one square meter basement ceiling must be at least 210 kg.

Ceilings must be sufficiently rigid so that deflections do not form. Wooden floor beams can be used as logs for the floor of the next floor. To determine which timber to use, you need to touch the resistance mat a little. Such a lag calculation is usually performed by architects, and those who want to build with their own hands use tables.

When renovating or building a new room division element, sound insulation must be taken into account. How to do this and what are the requirements for soundproofing - this is determined by regulatory building documents. This requires carefully closing existing gaps at the joints of structural elements and using appropriate materials to fill the gap between the beams.

Ceilings that divide the room, having, at the same time, a difference in temperature, must comply with heat protection requirements normative documents. To do this, we use heaters that fit between the beams. Their number determines the calculation. To prevent the lags from becoming cold bridges, the choice of lag material must be approached with appropriate knowledge.

The scheme of the beam ceiling, consisting of beams and internal filling.

Any floor structure must withstand prolonged fire exposure. Fire resistance limit various designs ranges from 15 to 50 minutes. Reinforced concrete floors, in this sense - the most persistent, wooden - the weakest. Therefore, before using wooden beam, it is necessary to impregnate the wood of the beam with an appropriate fire-resistant material or use plastering of the finished structure.

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Types of floors

According to the type of construction, two types of overlap are distinguished. The first type is beam. It consists of beams and internal filling. The second type is a beamless design. Beamless is made of homogeneous elements, such as deck slabs or deck panels.

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Beamed wooden floors

The frame of such an overlap is wooden beams (logs), which should be fixed at a uniform distance from each other. The calculation of this distance is made depending on the section of the beam and the width of the span between the supporting walls.

Experts have long made such a calculation. The distance between will tell the table:

Section (for a wooden beam) cm x cm	Floor span width3 m	Floor span width3.5 m	Floor span width4 m	Floor span width4, 5 m	Floor span width5 m
Beam 5 x 16	0.8 m	0.6 m	0.45 m	—	—
Beam 6 x 20	1.25 m	0.80 m	0.70 m	0.55 m	0.45 m
Beam 10 x10	0.60 m	0.45 m	0.35 m	—	—
Beam 14 x 18	—	—	—	1,8	1,48
Beam 15 x 20	—	—	—	2,4	2,0
Beam 16 x 22	—	—	—	—	2,5

Wooden beam structures are perfect for building a private country house.

Unfortunately, these are not all the disadvantages of a floor using metal structural materials. Other disadvantages of such an overlap include:

Rust formation in damp rooms.
The need for lifting mechanisms during installation.
Good sound and thermal conductivity (these disadvantages are combated by wrapping the ends metal structures felt).

Rolling on such beams is not only from boards, but also from slabs. It can be lightweight reinforced concrete slabs or slabs from other lightweight and durable building materials- their application regulates the calculation.

To avoid corrosion of the bearing beams, use reinforced concrete beams overlap. Such beams are laid at a distance of 0.6 -1.0 m. It is easy to fill the space between the beams concrete slabs or lightweight concrete blocks. On top of such an overlap, a screed is made under the floor, and the ceiling is plastered for whitewashing, painting or wallpaper.

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Beamless floors

Perform, at the same time, both the carrier and the enclosing (separating) functions. There are no beam crossbars in their design, and they consist of monolithic slab or several slabs or panels. There are three types of beamless floors:

Prefabricated.
Monolithic.
Prefabricated monolithic.

Prefabricated ceilings cannot be assembled by hand, as this requires lifting mechanism and slingers. But such an overlap is quickly assembled and withstands heavy loads. It is assembled from hollow or U-shaped reinforced concrete slabs. For installation of coatings logs made of wood can be used.

With their own hands, most often, they make. It can be done slowly and slowly. The most time-consuming and responsible stage in its implementation is the installation of suspended formwork and reinforcement. Pouring a layer of concrete 8 - 12 cm, compared with these painstaking work, seems like a rest. Do-it-yourself concrete of the M200 brand is poured, any reinforcement is used.

To lay the floor on such a structure, it is desirable to lay wooden logs. For linoleum flooring or tiles, logs do not need to be laid.

For interfloor or attic floors not economical to use. For example, when the span is too large and therefore wooden beams are required to span it large section. Or when you have a good friend who sells not lumber, but rolled metal.

In any case, it will not be superfluous to know how much the ceiling can cost if you use metal beams rather than wooden ones. And this calculator will help you with this. With it, you can calculate the required moment of resistance and moment of inertia, which for selection of metal beams for ceilings according to assortments from the condition of strength and deflection.

The floor beam is calculated for bending as a single-span hinged-supported beam.

Calculator

Related Calculators:

Instructions for the calculator

Initial data

Operating conditions:

Span length (L)- the distance between the two inner faces of the walls. In other words, the span spanned by the calculated beams.

Beam pitch (P)- a step in the center of the beams through which they are laid.

Type of overlap- in case the last floor You will not live, and he will not be heavily littered with things dear to your heart, then he gets out "Attic", in other cases - "Interfloor".

Wall length (X)- the length of the wall on which the beams rest.

Beam characteristics:

Beam length (A)- the largest size of the beam.

Weight 1 p.m. - this parameter is used, as it were, in the second stage (after you have already selected the desired beam).

Design resistance R y - this parameter depends on the steel grade. For example, if the steel grade is:

C235 - Ry = 230 MPa;
C255 - Ry = 250 MPa;
C345 - Ry = 335 MPa;

But usually Ry = 210 MPa is used in the calculation in order to protect oneself from different kind"force majeure" situations. Still, we live in Russia - they will bring rolled metal from steel of the wrong grade and that's it ...

Elastic modulus E- This parameter depends on the type of metal. For the most common, its value is:

steel - E = 200,000 MPa;
aluminum - E = 70,000 MPa.

Values normative and design loads are indicated after their collection for overlapping.

Price for 1 ton- the cost of 1 ton of rolled metal.

Result

Strength calculation:

W required - required section modulus. It is located according to the assortment (there are GOSTs for profiles). The direction (x-x, y-y) is chosen depending on how the beam will lie. For example, for a channel and an I-beam, if you want to install them (i.e. larger size directed up - [ and Ι ), you need to select "x-x".

Deflection calculation:

J required - the minimum allowable moment of inertia. It is selected according to the same assortments and according to the same principles as W req.

Other options:

Number of beams- the total number of beams, which is obtained when laying them on the wall X step by step P.

total weight- weight of all beams length A.

Price- the cost of buying metal floor beams.

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 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, is taken depending on the geographical location of the building);
special load (seismic, explosive, etc. This calculator does not take into account);

The loads on the beam are divided into two types: design and standard. Design loads are used to calculate the strength and stability of the beam (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 we have collected the surface load on the ceiling, 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 turned out to be Qsurface = 500kg / m2, and the step 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 plot of moments is constructed, shear force. 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.

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 floors in a timber house

Interfloor;
Basement;
Basement.

The greatest load in the house falls on the basement and basement. Their horizontal partitions must support the weight of objects kitchen equipment, as well as the severity 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, enough plates the right sizes ordered from the factory. They are stacked in the house using lifting equipment. A monolithic floors 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. In private one and two-storey houses aerated concrete slabs are used. 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 redundant. 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 it absorbs the moisture of the environment well.

In construction practice, mixed partitions are used various materials. wooden beams to increase strength, reinforce with metal. At monolithic structures applies a variety of removable formwork. 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 construction 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 wooden log. In Russia, 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 soundproofing.

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 details treated with antiseptics that prevent decay, damage by insects. 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 raise fire safety, wood is treated with solutions that do not allow it to flare up immediately when an open fire appears.

Installation interfloor structures start 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.

Beams are reinforced with anchors in niches 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.

In the construction of residential buildings and other structures, everyone is faced with the need for proper 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.). Moreover, this design is a carrier, since 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 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 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 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. 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 - 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

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:

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.