The maximum load that the beam can withstand is 100x100. What loads can the beam withstand? An example of calculating a wooden beam

One of the most popular solutions for arranging interfloor floors in private homes is to use load-bearing structure from wooden beams. It must withstand the design loads without bending and, moreover, without collapsing. Before proceeding with the construction of the ceiling, we recommend using our online calculator and calculating the main parameters of the beam structure.

Publication date: 03/03/2018 00:00

What loads can the beam withstand?

Beam and logs have long been used in Russia for the construction of houses. wooden buildings have a number of advantages:

• Ease of construction.
• High construction speed;
• Low cost.
• Unique microclimate. The wooden house “breathes”, the air in it is much lighter and more pleasant;
• Excellent operational characteristics;
• A wooden house holds heat well. He's warmer brick buildings 6 times, and buildings made of foam concrete 1.5 times;
• Various types and sizes of this lumber allow you to realize a wide variety of projects and design ideas.

This type of building material is a log of rectangular section. It is considered the cheapest lumber and at the same time very convenient for construction.

A beam is made from saw logs, conifers.

• Double-edged - only two opposite sides are processed (cut off at the log), while the other two are left rounded.
• Three-edged. There are three sides cut off.
• Four-edged - cut 4-sides.

Dimensions:

The standard length of the beam is 6 meters. Glued laminated timber is a prefabricated structure, so here the length can reach 18 meters.

Section dimensions

• Thickness from 100 to 250 mm. The section step size is 25 mm, that is, the thickness is 100, 125.
• Width from 100 mm to 275 mm.

The choice of cross-section of the beam must be approached with particular care. After all, the safety of the building will depend on what load this building material can withstand.

For the correct calculation of the load, there are special formulas and programs.

1. Permanent. These are the loads on the beam that the entire structure of the building exerts, the weight of the insulation, finishing materials and roofs.

2. Temporary. These loads can be short-term, rare and long-term. These include soil movements and erosion, wind and snow loads, the weight of people at construction work. Snow loads are different, they depend on the region where the building was erected. In the north, the snow cover is greater, so the load on the timber will be higher.

In order for the calculation of the load to be correct in the formula (it can be found on the Internet), both types of loads, the characteristics of the building material, its quality, and humidity must be entered. Especially carefully you need to calculate the load on the timber during the construction of the rafters.

What load can a beam 150x150 withstand A bar with a section of 15 by 15 cm is widely used in the construction of buildings. It is used for the manufacture of supports, formwork and for the construction of walls, as it can withstand heavy loads. But the size of 15 by 15 is better to use for building houses in the southern regions, in the north you need additional insulation walls, since this lumber stores heat only at an air temperature of -15 degrees. But if you use a glued beam of this size, then in terms of its heat-saving properties it will be equal to a beam with a section of 25 by 20 cm.

What load can a beam 100 by 100 mm withstand

This beam is no longer so reliable, it can withstand less load, so its main application - manufacturing rafters and ceilings between floors. It is also necessary in the construction of stairs, the manufacture of props, arches, the design of attics, the ceiling of the house. You can also make a frame of a panel one-story house out of it.

What load can a beam 50 by 50 mm withstand

A beam of 50x50 mm is in great demand. You can’t do without this size when, the way it is auxiliary material. Of course, it is not suitable for building walls, since it can withstand a small load, but for building battens for exterior finish walls, frames, partitions, this size is needed. A wall frame is made from a 50 by 50 timber, onto which drywall is then attached. Here you can use a wide variety of fasteners from nails to staples or wire.

The beams in the house usually refer to the truss system or ceiling, and in order to get robust design which can be operated without any concern, it is necessary to use beam calculator.

What is the beam calculator based on

When the walls are already brought under the second floor or under the roof, it is necessary to do, in the second case, smoothly turning into rafter legs. In this case, the materials must be selected so that the load on the brick or log walls did not exceed the allowable, and the strength of the structure was at the proper level. Therefore, if you are going to use wood, you need to choose the right beams from it, make calculations to find out desired thickness and of sufficient length.

Sagging or partial destruction of the floor can be caused by various reasons, for example, too large a step between the lags, deflection of the crossbars, too small a cross-sectional area or defects in the structure. To exclude possible excesses, it is necessary to find out the estimated load on the floor, whether it is basement or interfloor, after which we use the beam calculator, taking into account their own mass. The latter can vary in concrete lintels, the weight of which depends on the density of reinforcement; for wood and metal, with a certain geometry, the mass is constant. An exception is damp wood, which is not used in construction work without prior drying.

On beam systems in floors and roof structures exert a load of forces acting on the bending of the section, on torsion, on deflection along the length. For rafters, it is also necessary to provide for snow and wind loads, which also create certain forces applied to the beams. It is also necessary to accurately define necessary step between jumpers, because too a large number of crossbars will lead to excess mass of the floor (or roof), and too little, as mentioned above, will weaken the structure.

You may also be interested in the article on calculating the amount of unedged and edged board cubed:

How to calculate the load on the floor beam

The distance between the walls is called a span, and there are two of them in a room, and one span will necessarily be smaller than the other if the shape of the room is not square. Jumpers interfloor or attic floor should be laid over a shorter span, optimal length which is from 3 to 4 meters. Beams may be required for larger distances custom sizes, which will lead to some fluctuation of the flooring. The best way out in this case would be to use metal crossbars.

As for the section of a wooden beam, there is a certain standard that requires that the sides of the beam be in a ratio of 7: 5, that is, the height is divided into 7 parts, and 5 of them should make up the width of the profile. In this case, the deformation of the section is excluded, but if you deviate from the above indicators, then with a width exceeding the height, you will get a deflection, or, in case of a reverse discrepancy, a bend to the side. To prevent this from happening due to the excessive length of the beam, you need to know how to calculate the load on the beam. In particular, the allowable deflection is calculated from the ratio to the length of the jumper, as 1:200, that is, it should be 2 centimeters by 4 meters.

So that the timber does not sag under the weight of the lags and flooring, as well as interior items, you can carve it from below by several centimeters, giving it the shape of an arch, in which case its height should have an appropriate margin.

Now let's turn to the formulas. The same deflection, which was mentioned earlier, is calculated as follows: fnorm \u003d L / 200, where L- the span length, and 200 - the allowable distance in centimeters for each unit of subsidence of the timber. For reinforced concrete beam, distributed load q to which 400 kg / m 2 is usually equated, the calculation of the limiting bending moment is performed according to the formula M max \u003d (q · L 2) / 8. In this case, the number of reinforcement and its weight is determined according to the following table:

Cross-sectional areas and masses of reinforcing bars

The load on any beam of sufficiently homogeneous material is calculated using a number of formulas. To begin with, the moment of resistance W ≥ M / R is calculated. Here M is the maximum bending moment of the applied load, and R – design resistance, which is taken from reference books depending on the material used. Since most beams have rectangular shape, the moment of resistance can be calculated differently: W z \u003d b h 2 / 6, where b is the width of the beam, and h- height.

What else you should know about beam loads

The ceiling, as a rule, is at the same time the floor of the next floor and the ceiling of the previous one. So, you need to make it so that there is no risk of combining the upper and lower rooms by simply overloading the furniture. This is especially likely to occur when big step between the beams and the rejection of lags (plank floors are laid directly on the timber laid in the spans). In this case, the distance between the crossbars directly depends on the thickness of the boards, for example, if it is 28 millimeters, then the length of the board should not be more than 50 centimeters. In the presence of lags, the minimum gap between the beams can reach 1 meter.

You should also take into account the mass used for the floor. For example, if mats are laid from mineral wool, then square meter basement floor will weigh from 90 to 120 kilograms, depending on the thickness of the thermal insulation. Sawdust concrete will double the mass of the same area. The use of expanded clay will make the floor even harder, since the load per square meter will be 3 times more than when laying mineral wool. Further, we should not forget about the payload, which for interfloor ceilings is 150 kilograms per square meter minimum. In the attic, it is enough to accept an allowable load of 75 kilograms per square.

It is possible to make a reliable overlap only with the right size of the beams. To determine this most accurate size, you will need to make a calculation. This can be done with online programs, which is a kind of calculator.

Why do you need to count?

All load on interfloor overlap, rests on wooden beams, so they are load-bearing. The integrity of the building and the safety of the people in it depend on the strength of the floor beams.
Make a calculation wooden elements necessary to determine the allowable vertical load acting on it. Construction of a new or reconstruction old building without preliminary calculation cross-section carries a huge risk.

A randomly built ceiling of weak wooden beams can collapse at any time, which will lead to large financial costs, and even worse, to injury to people. Large-section beams taken with a margin will create an extra load on the walls and the base of the building.

In addition to determining the strength, there is a calculation of the deflection of wooden elements. It determines the aesthetic side of the building more. Even if a strong floor beam can withstand the weight falling on it, it can bend. Except spoiled appearance, a sagging ceiling will create the discomfort of staying in such a room. According to the norms, the deflection should not exceed 1/250 of the beam length.

• Sunset of wooden beams made of timber in concrete or brick building must be at least 150 mm. If a board is used instead of a beam, its minimum entry is 100 mm. By wooden houses indicator is slightly different. The minimum entry of an element made from a bar or a board is 70 mm;
• When using metal fasteners, the span should be equal to the length of the floor structure. The weight of the ceiling and other elements will fall on the metal parts;
• The standard layout of the house has a span of 2.5–4 m. It can be covered with a six-meter element. Large spans overlap with glued beams or build additional partition walls.

Using a regular calculator to calculate, these recommendations will help to make a strong overlap.

Load definition

The overlap, together with the objects on it, creates a certain load on the wooden beams. It can be accurately calculated only in design organizations. An approximate calculation is made with a calculator, using the following recommendations:

• Attics insulated with mineral wool and hemmed with boards are distinguished by a minimum load, approximately 50 kg / m2. The calculation of the load is performed according to the formula: the value of the margin of safety - 1.3 is multiplied by the indicator maximum load - 70.
• If instead of mineral wool a heavier heat insulator and a massive hemmed board are used, the load increases to an average of 150 kg / m2. You can determine the total load in the following way: The safety factor value is multiplied by average load and the size of the required load is added to everything.
• When making a calculation for the attic, the load is allowed up to 350 kg / m2. This is due to the fact that the weight of the floor, furniture, etc. is added.

With this definition sorted out, now we go further.

Determination of the section and the installation step of the floor elements

This process requires adherence to the following rules:

1. The ratio of the width to the height of the structure is equal to 1.4 / 1. Therefore, the width of the floor elements depends on this indicator and can vary from 40 to 200 mm. The thickness and height of the wooden elements depends on the thickness of the thermal insulation, approximately 100–3000 mm;
2. The distance between the elements, that is, their pitch, can be from 300 to 1200 mm. Here it is necessary to take into account the dimensions of the thermal insulation with the hemming material. AT frame building the distance between the beams is equated to the step of the frame racks;
3. A slight bend is allowed for wooden beams, which is 1/200 for the attic floor, and 1/350 for the interfloor;
4. With a load of 400 kg/m2, the pitch to section ratio is 75/100 mm. In general, the larger the cross section of the beams, the more distance between them.

When using a calculator to determine the cross section, you must use reference materials for more accurate results.

In addition to the accurate results obtained, the strength of the structure depends on the quality of the material.

Blanks are used from coniferous wood, with a moisture content of up to 14%. Wood should not be affected by fungus and insects. Well, to increase the service life wooden structure, workpieces must be treated with an antiseptic before installation.
In the following video, you can watch an example of working in the program for calculating floors.

The main condition for any construction is the simplicity and reliability of the design, but in order to achieve this, it is necessary to produce correct calculations strength of the material. Since for the construction wooden houses, attic or attic space used wooden frame its choice must be approached with all responsibility, because the durability, reliability and stability of the built house will directly depend on what load the beam can withstand (100x100, 50x50, 150x150, etc.).

For the correct calculation of the load withstood by the beam, special programs or formulas can be used, but in this case, additional loads will have to be introduced into the calculations, which directly affect the strength of the structure. In order to calculate the load on the beam correctly, you will have to indicate the snow and wind effects that are present directly in the building region, as well as the characteristics of the materials used (heat isover, beam, etc.).

In this article, we will consider what kind of load a beam with a size of 50x50, 100x100, 150x150 can withstand. various designs, such as a log house, wooden floor and the truss system, and as an example, we will analyze the latter, because this is the most responsible and difficult work.

In the photo you can see the varieties of timber, which differ not only in shape, but also in the load capacity.

What will be discussed:

How does the cross-section of a log house affect its reliability?

When building a roof prerequisite its reliability is the cross-section of the timber used and the type of wood, which affects the durability.

Performing the calculation with your own hands, you will need to take into account such indicators as:

• what is the mass of all roofing building materials;
• the weight of the attic or attic finish;
• for rafter supports and beams, the calculated value is taken into account;
• the thermal and sedimentary effects of nature are taken into account.

In addition, you will need to specify:

• distance between beams;
• the length of the gap between the rafter supports;
• the principle of fastening the rafters and the configuration of its truss;
• the severity of precipitation and the effect of winds on the structure;
• other factors that may affect the reliability of the design.

All these calculations can be done manually using special formulas. But it will be simpler both in time and in quality to calculate the load of the beam using special programs, and even better when these calculations are performed by a professional.

What requirements must the beam meet?

So that the entire truss system is strong and reliable in quality building materials will have to take full responsibility. For example, there should be no defects on the beam (cracks, knots, etc.), and its moisture content should not exceed 20%. In addition, a log house of any size (50x50, 100x100, 150x150, etc.) must be processed protective equipment from shashel and other insects, rotting and fire.

Also, when choosing a material, you will have to take into account that additional loads may be applied to the timber, such as:

• Continuous load beam. These include directly the weight of the entire truss system, which includes: facing and roofing materials, heaters, etc. The data obtained for each material are summarized.
• Short-term loads can be of several types: especially rare, short-term and long-term effects. The first type includes incidents that happen very rarely (earthquakes, floods, etc.). Wind and snow impacts, the movement of people repairing the roof, etc. are short-lived. All other impacts that occur within a certain period of time are long-term loads.

We determine the wind and snow load on the beam

To determine what load the beam can withstand (100x100, 150x150.50x50, etc.) under wind and snow exposure, you can use certain tables.

To determine the effect of snow on the rafters different section apply the formula S=Sg*µ.

• Sg - is the calculated weight of snow lying on the ground, which affects 1 m².

Important! This value cannot be compared with the roof load.

• µ is the value of the load on the roof surface, which varies from horizontal to sloping. This coefficient can take various meanings, it all depends on the slope of the roof.

With a surface slope of up to 25 degrees, µ takes on the value 1.

When the slope of the roof is in the range of 25-60 degrees, µ is 0.7.

With a slope of 60 degrees or more, the coefficient µ is not taken into account because it practically does not affect the truss system.

Apart from snow load before the construction of the truss system, the wind load on wooden beam 50 to 50, 100x100, etc. If these indicators are not taken into account, as a result, everything can end in failure. Table values ​​and the formula W=Wo*k are used for the calculation.

Wo - is a tabular value of the wind load for each individual region.

k is the wind pressure, which has different meanings as altitude changes. These indicators are also tabular.

The table of beam loads shown in the photo when exposed to the elements is easy to use, you just need to remember that the 1st column shows the values ​​\u200b\u200bfor the steppe, desert regions, rivers, lakes, forest-steppe, tundra, seashores and reservoirs. The next column contains data related to urban areas and areas with 10 meter obstacles.

Important! In calculations, it is desirable to use information on the direction of wind movement, because this can make an important correction to the results.

By what rules is the desired cross section of the beam calculated?

Several parameters influence the selection of the log section for the truss system:

• what is the length of the rafter construction;
• the distance between each subsequent beam;
• the results of load calculations for the corresponding area.

To date, for each specific area, there are special tables with data already entered on the load values ​​for truss systems. An example is the Moscow region:

• in order to install a Mauerlat, you can use a bar with a section of at least 100x100, 150x100 and 150x150;
• timber 200x100 can be used for diagonal valleys and rafter supports (legs);
• runs can be created from wood 100x100, 150x100 or 200x100;
• log house 150x50 will become optimal solution for tightening;
• it is best to use a log house 150x150 or 100x100 as racks;
• a 150x50 rafter is suitable for a cornice, struts or filly;
• crossbars are best installed from rafters 150x100 or 200x100;
• As a sheathing or frontal, you can use a board of at least 22x100.

The above data are optimal, that is, less than this value, the material cannot be used. Also, all dimensions are in millimeters.

Summarize

To create a reliable and durable wooden structure, you need to carefully calculate everything possible loads, after which only to acquire timber. If you have doubts about the correctness of the calculations, it is best to use the services of a professional or use a special program that will calculate permissible load on a bar (150x150, 100x100, etc.).