Construction calculator for foundations with reinforcement. Shallow strip foundation - calculation and design. Calculation of reinforcement for the frame

When constructing any building, it is important to correctly calculate the foundation. Calculate the foundation You can do this with the help of specialists or independently using a foundation calculator. Let's consider the most important points, this includes load calculation, the volume of the foundation pit and tips that need to be taken into account when creating a house foundation project. To calculate the foundation, you can use the foundation calculator.

1. Calculate the weight of the house structure.

An example of calculating the weight of a house structure: You want to build a house with a height of 1 floor, 5 m by 8 m, also an internal wall, the height of floor to ceiling is 3 meters.

Let's substitute the data and calculate the length of the walls: 5+8=13 meters, add the length of the inner wall: 13+5=18 meters. As a result, we get the length of all the walls, then we calculate the area, multiply the length by the height: S = 18 * 3 = 54 m.

We calculate basement floor area, multiply the length by the width: S=5*8=40 m. The attic floor will have the same area.

We calculate roof area, multiply the length of the sheet by the width, for example, a sheet of roofing has a length of 6 meters, and a width of 2 meters, as a result the area of ​​one sheet will be 12 m, in total we will need 4 sheets on each side. In total, you will get 8 roofing sheets with an area of ​​12 m. The total area of ​​the roofing will be 8 * 12 = 96 m.

2. Calculate the amount of concrete required for the foundation.

To begin the construction of a building, you need to draw up a project for the foundation of a private building, from which you can calculate the required amount of building materials for the construction of the structure. In our case, it is necessary to calculate the amount of concrete to create the foundation. The type of foundation and various parameters serve to calculate the amount of concrete.

3. Calculation of foundation area and weight.

The most important factor is the soil under the foundation; it may not withstand high loads. To avoid this, you need to calculate the total weight of the building, including the foundation.

An example of calculating the weight of a foundation: You want to build a brick building and have selected a strip foundation for it. The foundation goes deep into the ground below the freezing depth and will have a height of 2 meters.

Then we calculate the length of the entire tape, that is, the perimeter: P= (a+b)*2=(5+8)*2=26 m, add the length of the internal wall, 5 meters, and in the end we get the total length of the foundation 31 m.

Next we do volume calculation To do this, you need to multiply the width of the foundation by the length and height, let’s say the width is 50 cm, which means 0.5 cm * 31 m * 2 m = 31 m 2. Reinforced concrete has an area of ​​2400 kg/m3, now let’s find the weight of the foundation structure: 31m3*2400 kg/m=74 tons 400 kilograms.

The supporting area will be 3100*50=15500 cm2. Now we add the weight of the foundation to the weight of the building and divide it by the supporting area, now you have a load of kilograms per 1 cm 2.

Well, if, according to your calculations, the maximum load exceeded these types of soils, then we change the size of the foundation to increase its supporting area. If you have a strip foundation, then you can increase its supporting area by increasing the width, and if you have a columnar foundation, then increase the size of the column or their number. But remember, this will increase the total weight of the house, so it is recommended to re-calculate.

Construction technologies have been developing over many centuries.

One of essential elements Any building is the foundation, which ensures the integrity and durability of the entire house.

The main and most successful version of the base design is a simple and reliable type of support system.

With the advent of high-quality and affordable concrete, the tape has gained capabilities that are far superior to the properties of alternative options, primarily in terms of load-bearing capacity and efficiency.

At the same time, the performance of the tape is almost completely determined by the quality of the material, its composition and properties.

Class and grade are two independent quantities indicating the quality of concrete.

Both of them reflect the degree of compressive strength of the material, but differ in specialization.

Grade (M) - an indicator related to the quantitative value of cement content. Class (B) - an indicator of the material’s resistance to external loads.

The grade of concrete demonstrates the cement content. This is a very unstable and uninformative indicator, the main value of which is the freezing time.

Two pieces of hardened concrete with different qualities can have the same grade, since the cement content does not completely determine the finishing quality of the material. There are brands from M50 to M500.

The most common of them is M200, which is used for, production of stairs and other structural elements.

Smaller grades are used to fill the preparatory layer of the strip foundation or auxiliary elements.

More durable grades - M300-M500 are used for casting special structures, dams, and critical reinforced concrete parts.

Unlike the grade, which shows the average strength value and allows significant fluctuations in quality, the concrete class indicates the ultimate strength, which is ensured in 95% of cases.

The class is a more accurate indicator, so most manufacturers switch to class when designating the quality of a material, although the use of the brand by inertia is also widespread.

Online calculator

Scheme for calculating cubic capacity for strip foundations

The volume of concrete is calculated based on the design parameters of the tape. In order to determine the required amount of material, it is necessary to calculate the volume of the tape.

The cross-sectional area is determined by multiplying the width by the height. Then the resulting value is multiplied by the total length of the strip foundation, taking into account the length of all sections, including lintels.

It is necessary to use the same units of measurement to avoid confusion in determining the digits.

If the length of the tape is in meters, then the cross-section must be calculated in square meters.

IMPORTANT!

Some sellers list their goods in tons, while others count their goods in cubic meters. The volume of concrete obtained in the calculation may need to be converted into weight units, for which it is necessary to know the specific gravity of the concrete of the desired grade. This table value, available in SNiP annexes. The volume is multiplied by the specific gravity to obtain the total amount of material.

How to count

Let's consider a specific example of calculation. There is a tape with a total length of 30 m, a width of 40 cm and a height of 1 m.

Determining the cross section:

0.4 1 = 0.4 m2.

Tape volume:

0.4 30 = 12 m3.

Weight of concrete (grade M200):

2.432 12 = 29.184 tons.

NOTE!

All values ​​must be increased by 10-15% in order to have some reserve just in case. Therefore, it is necessary to prepare the material at the rate of 32 tons (we increase 29.2 by about 10%).

What requirements must it meet?

Basic requirements for concrete used in the manufacture of critical load-bearing structures:

• Strength, resistance to all external loads.
• High load-bearing capacity.
• The combination of components should provide maximum compressive and torsional strength.
• High frost resistance.
• Resistance to moisture (for the most critical structures, special hydrophobic additives are used).

The numerical values ​​of the required parameters are determined by the purpose of the tape, magnitude of loads and operating conditions.

Self-production requires experience, the use of equipment and several assistants, otherwise there is a risk of interrupting the pouring of the foundation, which is unacceptable.

In what proportions should it be mixed?

If for some reason it is not possible to order ready-made concrete, you have to prepare it yourself. To do this, you need to know what components are used in the manufacture of the material and in what quantities they are present in the mixture.

Common types of concrete consist of the following elements:

• Sand.
• Crushed stone.
• Cement.
• Water.

IMPORTANT!

Do not confuse concrete for pouring the foundation and mortar for laying bricks. These are different materials. No additives for elasticity (soap solutions or lime) should be added. The material should be as rigid as possible.

The most common proportion for making structural types of concrete:

• Cement - 1 part.
• Sand - 3 parts.
• Crushed stone - 5 parts.
• Water - 0.5 parts.

Depending on the specialization and characteristics of the foundation, these proportions may change in one direction or another.

The cement usually used for the production of heavy concrete belongs to the M400 or M500 grades. Smaller species are not suitable for such purposes.

The sand must be clean and free of foreign impurities. Used river, less often - washed gully, without foreign impurities.

Organic matter and clay inclusions are especially undesirable. They increase the creep and shrinkage of the material, so they need to be gotten rid of.

The crushed stone used in preparing the mixture must be of medium size (1-3 cm) and free of organic impurities.

The presence of aggregates (sand and crushed stone) in concrete is mandatory. Water and cement form the so-called. concrete stone, highly susceptible to shrinkage, reaching up to 2 mm per meter of height.

The presence of fillers reduces shrinkage and forms a kind of, receiving loads and redistributing them throughout the entire volume of the material.

When talking about the proportions of concrete, we should focus on the units of measurement. Usually parts are counted in weight units.

In practice, they most often use volumetric measures, for example, buckets.

It must be borne in mind that the weight of one bucket is different for each material:

• Sand - 19 kg.
• Cement - 15 kg.
• Crushed stone - 17.5 kg.

Taking into account the difference in volumetric weight, the optimal proportion of components (in buckets) will be the ratio 2-5-9 (C-P-SC).

Water is usually added to half the volume of cement. Knowledge of these subtleties will allow you to mix the composition correctly and avoid mistakes when creating such a critical design as strip foundation.

How to knead correctly

The best way to make concrete is to use a concrete mixer. It is not necessary to purchase it for your own use; you can rent the device for several days.

It is necessary to mix such an amount of material that can be used in 2 hours.

This rule allows material to be supplied rhythmically to the site without overloading workers..

It should be noted that the most important thing is to do the work as quickly as possible, so you should be guided by the requirements of the situation.

Concrete is mixed as follows::

• The required quantities of sand, cement and crushed stone are poured into a concrete mixer or a specially designated container.
• They are thoroughly mixed until a homogeneous mixture is obtained.
• Water is gradually poured in. Throughout the entire process, the material is constantly mixed.
• The result should be concrete that mixes fairly easily and does not roll off the shovel too freely.

If wet sand is used, the amount of water should be reduced slightly. In general, the consistency of the material is determined by your own feelings.

If necessary, add water, since the concrete is poured into it. Material that is too thick does not lay down evenly and forms bubbles that are difficult to get rid of.

Useful video

In this section you will find out how much concrete is needed for a strip foundation:

Conclusion

The quality of concrete directly depends on the properties of the components, proportions and manufacturing technology.

At self-production It is possible to control the composition of the mixture, but when using ready-mixed concrete, greater quality tolerances should be taken into account and a heavier grade should be chosen.

This will not make a big difference in costs, but will help to obtain a high-quality and durable material for filling the tape.

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A strip foundation is a prefabricated or monolithic foundation made of high-strength reinforced concrete blocks, which are laid along the perimeter of the future structure, as well as in areas of load-bearing structures. The formation of a strip foundation does not involve the use of heavy construction equipment, but at the same time it requires absolute accuracy of calculation and measurement operations. The interactive strip foundation calculator will allow you to quickly and accurately calculate the proportion of sand, cement and crushed stone when making concrete manually, the dimensions of the strip, as well as the parameters of the formwork and foundation reinforcement for a house made of foam concrete or aerated concrete.

Advantages of the online strip foundation calculator

• Saves time, nerves, effort and money when drawing up cost estimates for the purchase of building materials.
• Allows you to estimate the volume of creative actions, as well as predict the timing of the formation of a strip-type foundation.
• Proper calculation of the parameters of reinforcement and concrete guarantees high strength and reliability of the internal frame of the structure.
• The ability to instantly calculate parameters for a monolithic or prefabricated, shallow or deeply laid strip foundation.
• 2D and 3D visualization options allow you to clearly assess the adequacy of calculation manipulations and make the necessary corrections in a timely manner.

Problems that the calculator solves

Calculation of reinforcement for a strip foundation helps determine the total length and weight of the reinforcement cage, as well as the minimum diameter of the transverse and longitudinal bars, the number of rows in the reinforcement chords, the spacing of the clamps and the amount of overlap. Calculations are made in accordance with the rules of SP 52-101-2003.

Calculation of concrete for a strip foundation provides information on the proportions of sand, crushed stone and cement, as well as the weight of the main building material for pouring the strip foundation. The calculation results make it possible to correctly and competently distribute the load across the structure segments.

The calculation of the formwork specifies the total length of the perimeter, as well as the area of ​​the base and the outer side edge of the reinforced concrete strip.

An online calculator for calculating strip foundations works for you completely free of charge. If you have any questions, write below in the comments - we will definitely help you.

Calculating the load on the foundation from the future house, along with determining the properties of the soil at the building site, are two primary tasks that must be performed when designing any foundation.

An approximate assessment of the characteristics of load-bearing soils on our own was discussed in the article. And here is a calculator with which you can determine the total weight of the house being built. The obtained result is used to calculate the parameters of the selected type of foundation. A description of the structure and operation of the calculator is given directly below.

Working with the calculator

Step 1: We mark the shape of the house box we have. There are two options: either the box of the house has the shape of a simple rectangle (square), or any other shape of a complex polygon (the house has more than four corners, there are protrusions, bay windows, etc.).

When choosing the first option, you need to specify the length (A-B) and width (1-2) of the house, while the values ​​​​of the perimeter of the external walls and the area of ​​the house in plan required for further calculations are calculated automatically.

When choosing the second option, the perimeter and area must be calculated independently (on a piece of paper), because the options for the shape of the house box are very diverse and everyone has their own. The resulting numbers are entered into the calculator. Pay attention to the units of measurement. Calculations are carried out in meters, square meters and kilograms.

Step 2: We indicate the parameters of the basement of the house. In simple words, the base is the lower part of the walls of the house, rising above the ground level. It can be executed in several versions:

1. the base is the upper part of the strip foundation protruding above the ground level.
2. the base is a separate part of the house, the material of which differs from both the foundation material and the material of the walls, for example, the foundation is made of monolithic concrete, the walls are made of timber, and the base is made of brick.
3. the base is made of the same material as the outer walls, but since it is often lined with other materials than the walls and does not have interior decoration, we therefore consider it separately.

In any case, measure the height of the plinth from the ground level to the level on which the plinth rests.

Step 3: We indicate the parameters of the external walls of the house. Their height is measured from the top of the plinth to the roof or to the base of the pediment, as indicated in the figure.

The total area of ​​the gables as well as the area of ​​windows and doorways in external walls you need to calculate based on the project yourself and enter the obtained values ​​into the calculator.

The calculation includes the average statistical figures for the specific weight of window structures with double-glazed windows (35 kg/m²) and doors (15 kg/m²).

Step 4: We indicate the parameters of partitions in the house. In the calculator, load-bearing and non-load-bearing partitions are considered separately. This was done on purpose, since in most cases the load-bearing partitions are more massive (they take the load from the floors or roof). Non-load-bearing partitions are simply enclosing structures and can be built, for example, simply from plasterboard.

Step 5: Specify roof parameters. First of all, we select its shape and, based on it, set the required dimensions. For typical roofs, the areas of the slopes and their angles of inclination are calculated automatically. If your roof has a complex configuration, then the area of ​​its slopes and their angle of inclination, necessary for further calculations, will have to be determined again independently on a piece of paper.

The weight of the roofing covering in the calculator is calculated taking into account the weight rafter system, taken equal to 25 kg/m².

The calculation in the calculator is made based on formula (10.1) from SP 20.13330.2011 (Updated version of SNiP 2.01.07-85*):

S 0 = 1.4 ∗ 0.7 ∗ c e ∗ c t ∗ μ ∗ S g ,

where 1.4 is the reliability coefficient for snow load adopted according to paragraph (10.12);

0.7 - reduction factor depending on the average temperature in January for a given region. This coefficient is taken equal to one when the average January temperature is above -5º C. But since almost throughout the entire territory of our country the average January temperatures are below this mark (visible on map 5 of Appendix G of this SNiP), then in the calculator the change in the coefficient is 0.7 by 1 not provided.

c e and c t - coefficient taking into account snow drift and thermal coefficient. Their values ​​are taken equal to unity to facilitate calculations.

S g - the weight of the snow cover per 1 m² of the horizontal projection of the roof, determined based on the snow area we selected on the map;

μ is a coefficient whose value depends on the angle of inclination of the roof slopes. At an angle of more than 60º μ =0 (i.e. the snow load is not taken into account at all). At an angle less than 30º μ =1. At intermediate values ​​of the angle of inclination of the slopes, it is necessary to perform interpolation. The calculator does this based on a simple formula:

μ = 2 - α/30, where α is the slope angle in degrees

Step 6: Specify the parameters of the floors. In addition to the weight of the structures themselves, the calculation includes an operational load of 195 kg/m² for the basement and interfloor floors and 90 kg/m² for the attic floor.

Having entered all the initial data, click the “CALCULATE!” button. Whenever you change any of the initial values, also click this button to update the results.

Note! Wind load is not taken into account when collecting foundation loads in low-rise construction. You can look at paragraph (10.14) SNiP 2.01.07-85* “Loads and impacts”.

Then the cross-sectional area will be:

40 100 = 4000 cm2.

Determine the total cross-sectional area of ​​the reinforcement (minimum):

4000: 1000 = 4 cm2.

Since the width of the tape is 40 cm, 2 rods need to be placed in one grid, and the total quantity is 4 pieces.

Then minimum area The cross section of one rod will be 1 cm2. Using SNiP tables (or from other sources) we find the closest value. In this case, you can use reinforcing bars with a thickness of 12 mm.

Determine the number of longitudinal rods. Let's say the total length of the tape is 30 m (tape 6: 6 m with one jumper 6 m).

Then the number of working rods with a length of 6 m will be:

(30: 6) 4 = 20 pcs.

Determine the number of vertical rods. Let's say the clamp pitch is 50 cm.

Then, with a tape length of 30 m, you will need:

30: 0.5 = 60 pcs.

Determine the length of one clamp.

To do this, subtract 10 cm from the width and height of the section and add up the results:

(40 - 10) + (100 - 10) = 120 cm. The length of one clamp is 120 2 = 140 cm = 2.4 m.

Total length of vertical reinforcement:

2.4 60 = 144 m. The number of rods with a length of 6 m will be 144: 6 = 24 pcs.

NOTE!

The obtained values ​​should be increased by 10-15% in order to have a margin in case of errors or unexpected material costs.

Types and sizes

There are two main :

• Metal.
• Composite.

The metal bars used to assemble the reinforcement cage have a ribbed or smooth surface.

Ribbed rods are used for horizontal (working) reinforcement, as they have an increased adhesion force to concrete, which is necessary to perform their functions efficiently.

Vertical rods, as a rule, are smooth, since their task is to maintain the working rods in the desired position until pouring. The diameter of the rods ranges from 5.5 to 80 mm. Working rods of 10, 12 and 14 mm and smooth rods of 6-8 mm are used.

Composite reinforcement consists of different elements:

• Glass.
• Carbon.
• Basalt.
• Aramid.
• Polymer additives.

Fiberglass reinforcement is the most widely used.

It has the greatest strength, the most rigid and resistant to tensile loads of all other options.

Like all types of composite rods, fiberglass reinforcement is completely resistant to moisture.

Manufacturers claim constant performance throughout the entire service period, but in practice the validity of this statement has not yet been verified. The problem with composite reinforcement is the complexity of the technology, due to which the quality of the material differs markedly from different manufacturers.

In addition, composite rods are not able to bend, which is inconvenient when assembling frames and reduces the strength of the corner joints of the frame.

IMPORTANT!

Among builders, the attitude towards composite reinforcement is complex. Without denying positive qualities, they do not trust little-studied ones too much building materials that have not undergone a full cycle of operation. In addition, metal fittings have very specific specifications, while composite types have a fairly wide range of properties. All these factors limit the use of composite rods.

How to make the right choice

The choice of reinforcing bars is based on design data and builder preferences.

Typically, metal rods are chosen, although composite reinforcement is increasingly used every year in the construction of strip foundations. Preference is given to metal rods due to the ability to give them the necessary bend, which is impossible to do with fiberglass rods.

This is especially important when constructing belts with curved sections or when there are fracture angles other than 90°.

In addition, metal reinforcement is more economical, as it allows you to make clamps from a single rod, without having to create multiple connection points.

The diameters of the rods have long been worked out in practice; they are often chosen without preliminary calculation - for about 30 cm, a 10 mm rod is used, for strips with a width of 40 cm, 12 mm rods are chosen, and for a width of more than 50 cm - 14 mm. The thickness of the vertical reinforcement is determined by the height of the tape; up to 70 cm, 6 mm is chosen, and for heights above 70 cm, 8 mm or more.

Useful video

In this section you can also see how calculations are performed using the example of a real construction site:

Conclusion

A well-chosen reinforcement scheme and the material itself ensure the strength and resistance of the tape to possible loads.

Complex and problematic soils, prone to heaving or seasonal movements, require a responsible and attentive approach to.

It must be taken into account that all calculated values ​​determine the minimum design parameters that require some increase for a certain safety factor.

When choosing reinforcement and reinforcement scheme, you need to multiply all values ​​by 1.2-1.3 (reliability factor) to reduce the risk of unforeseen factors.

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