How to calculate the amount of reinforcement for a strip foundation using an online calculator + calculation of formwork and section parameters
The strip foundation occupies the main place among all supporting structures for buildings and structures.
It is able to work effectively on the most difficult soils and has an optimal set of performance qualities.
Monolithic tape structures do not lose their performance qualities for up to 150 years, which exceeds the service life of the walls of a house.
Such high possibilities arose due to the high rigidity and strength of the tape, which is ensured by the joint work of concrete and metal reinforcement.
Each of them performs its own function, together providing reliability and high load-bearing capacity of the strip base.
How does reinforcement work in a strip foundation?
The reinforcement cage is necessary to compensate for axial counter-directional (tensile) loads that arise in the tape when deforming influences appear - bending or twisting forces.
The peculiarity of concrete is its ability to take gigantic pressures without any consequences.
At the same time, it is practically defenseless against multidirectional efforts, quickly becomes covered with cracks and collapses .
Therefore, any forces applied at one point are extremely dangerous for the tape - for example, lateral or vertical heaving loads. Reinforcing bars are designed to absorb these forces.
There are horizontal (working) and vertical reinforcement . The main loads are taken by horizontal rods.
They have a larger diameter and a corrugated surface that has good adhesion to concrete.
Vertical rods serve two functions:
- Fixation of working reinforcement in the required position until concrete is poured.
- Partial compensation of twisting forces.
The first task is the main one, and the second one is additional, since the presence of such specific loads is observed quite rarely.
In most cases, vertical (smooth) reinforcement serves only as a supporting structure that holds the working rods in the required position until pouring.
They are quite thick, since pouring is a process with fairly intense impacts on the frame, concentrated at one point (the place where heavy material falls into the formwork), and also distributed along the entire length (bayoneting, processing with a vibrating plate) .
Online calculator
How to calculate the strip foundation of a house? A specially designed service can help you with this - a strip foundation construction calculator.
Instructions for using the calculator
There are many online calculators on the Internet that help calculate the parameters of strip foundations for all important positions . Calculating reinforcement with their help takes literally a couple of minutes.
For example, on the website you only need to enter your own data into the appropriate windows of the program and click the “calculate” button.
A reinforcement diagram is given, in which the main parameters must be indicated - the number of working rods in one row, the total number of rows, the distance between vertical bars, etc. The cost of fittings per unit is indicated in a separate window.
As a result, the program displays the quantity of reinforcement and the total price. The calculation is simple and quick; in addition to the reinforcement, the resource provides the parameters of all elements of the tape - formwork , amount of concrete, etc.
The disadvantage of this calculator is the need to know in advance the reinforcement scheme, the diameter of the rods and the market value of the material.
If you need to determine the number and cross-section of rods, the resource is useless. It provides only quantitative information, without touching on qualitative aspects, which is sometimes not quite what is needed .
Calculation procedure
Let's look at how to calculate the reinforcement cage of the tape yourself.
First of all, it is necessary to determine the number of working rods in one row. To do this, you will need to use the requirement of SP 52-101-2003, which limits the maximum distance between adjacent rods to 40 cm.
Considering that depth of the working reinforcement should not exceed 2-5 cm, we obtain :
- For tapes less than 50 cm thick - 2 working rods.
- For tapes wider than 50 cm - 3 rods.
In cases where it is possible to use both 2 and 3 rods in one row, they usually try to play it safe and take a larger value, since the foundation is a responsible and important section of the building.
The second stage is to determine the diameter of the working rods. To do this, you will need to calculate the cross-sectional area of the working part of the tape by multiplying the width by the height.
The total cross-sectional area of the reinforcement is 0.1% of the cross-section (this is the minimum possible value, it can be increased, but cannot be decreased).
Having received this value, you need to divide it by the number of working rods. Using the table of diameters of reinforcing bars, the most successful option is found, which is accepted for work.
The diameter of the vertical reinforcement is selected based on the height of the tape:
- For heights up to 60 cm - 6 mm.
- From 60 to 80 cm - 8 mm.
The diameter of the transverse rods is usually taken to be 6 mm.
To calculate the number of working rods, you need to multiply their number in the lattice by the total length of the tape, after which the resulting value is divided by the length of the working rod (usually 6 m, but it is better to find out exactly this value from the sellers).
Vertical reinforcement is calculated by multiplying the number of clamps by the length of the unit.
The quantity is obtained by dividing the total length of the tape by the pitch of the clamps (usually 50-70 cm).
An example of calculating the required parameters
Let's consider the calculation of reinforcement for a strip foundation using an example.
Let's assume that the height of the tape is 100 cm and the width is 40 cm (a common version of a shallow foundation).
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 the minimum cross-sectional area 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 (6: 6 m tape with one 6 m jumper).
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 pitch of the clamps 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.
Types and sizes
There are two main types of fittings:
- 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 for the high-quality performance of their functions.
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. For private house construction, 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.
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 the need to create several connection points .
The diameters of the rods have long been worked out in practice; they are often chosen without preliminary calculation - for a tape width of about 30 cm, a 10 mm rod is used, for tapes 40 cm wide, 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 .
Source: https://expert-dacha.pro/stroitelstvo/fundament/lentochnyj-f/armatura-kalkulyator.html
Diameter of reinforcement for a strip foundation - an example of a simplified calculation - Piles Mania
Activities for the construction of any building are preceded by design work, during which the type of foundation base and the required amount of materials for its construction are determined. An important part of the foundation is the reinforcement cage.
It increases the strength of the base, dampens tensile forces and bending loads, and also prevents the formation of cracks. To carry out the work, you need to understand how much reinforcement is needed to reinforce a strip foundation, as well as for a columnar and slab foundation.
Let's look at the features of the calculations.
Consumption of reinforcement for reinforcing strip foundations
We are preparing to calculate the amount of reinforcement for the foundation - important points
When planning the construction of a private house, you should pay special attention to the design of the reinforcement grid, which can withstand significant loads on the foundation. A qualified design of the load-bearing grid and the use of the optimal cross-section of the reinforcement makes it possible to ensure the required safety margin of the foundation base, as well as its long service life.
You can independently calculate the reinforcement for the foundation in various ways.:
- using software and online calculators that perform reinforcement calculations after entering operating parameters;
- performing manual calculations based on information about the design features of the foundation, the magnitude of the forces and the lattice parameters.
The foundation takes the load from the mass of the building and evenly distributes it onto the supporting surface of the soil.
The construction of buildings is carried out on various types of foundations:
- tape;
- slab;
- columnar.
Calculation of reinforcement for strip foundations
Before starting the calculations, you should understand the design of the power frame, which consists of the following elements:
- vertical and transverse rods, between which an equal interval is maintained;
- knitting wire connecting longitudinally located jumpers and vertical rods;
- couplings that provide a strong connection and elongation of reinforcing bars.
Each type of foundation has its own foundation reinforcement scheme, which depends on the following factors::
- soil characteristics;
- building dimensions;
- design features of the structure;
- current loads.
Reinforcement with a ribbed surface is used, which differs:
- section size;
- class;
- level of perceived loads;
- location in the power grid;
- cost.
Laying reinforcement in a strip foundation
For various foundations, the following information is determined based on calculations:
- amount of reinforcement for the foundation;
- assortment of vertical and transverse rods;
- total mass of the reinforcement frame;
- methods of fixing steel rods in a load-bearing structure;
- load-bearing lattice assembly technology;
- step of tying reinforcement elements.
It is important to perform the calculation correctly. In this case, the reinforcement for the foundation will provide the necessary margin of safety. Let's consider what initial data is needed for calculations, and also study the methodology for performing calculations for various types of foundations.
Calculation of the amount of reinforcement for a strip foundation
The strip-type base provides increased stability of buildings on various soils.
The structure is a concrete strip that follows the contour of the building and is located under the main walls.
Reinforcement with steel reinforcement increases the strength characteristics of the concrete base and has a positive effect on its durability. To construct a spatial lattice, you can use reinforcement with a diameter of 10 mm.
Initial data for performing calculations:
- length and width of the foundation base;
- section of reinforced concrete strip;
- spacing between frame elements;
- total number of strapping belts;
- size of the power grid cells.
How much reinforcement is needed for a foundation?
Let's consider the order of calculations:
- Calculate the total length of the tape outline.
- Calculate the number of elements in the belts.
- Determine the footage of the horizontal bars.
- Calculate the need for vertical rods.
- Calculate the length of the crossbars.
- Add up the resulting footage.
Knowing the total number of joint sections, you can calculate the need for binding wire.
Calculation of the amount of reinforcement for a slab-type foundation
The foundation of a slab structure is used for the construction of residential buildings on heaving soils. To ensure strength characteristics, reinforcing bars with a diameter of 10–12 mm are used. With increased mass of buildings, the diameter of the rods should be increased to 1.4–1.6 cm.
You can calculate the amount of reinforcement for the foundation of a slab structure using the following information:
- a spatial frame made of reinforcement is constructed in two levels;
- the connection of the rods is made in the form of square cells with a side of 15–20 cm;
- The binding is performed with annealed wire at each connection point.
Scheme of reinforcement of a monolithic foundation slab
To determine the need for reinforcement, perform the following operations:
- Determine the number of horizontal rods in each tier.
- Calculate the total footage of the reinforcing bars that form the cells.
- Add the total length of the vertical supports connecting the tiers.
Adding up the obtained values, we obtain the total need for reinforcement. Knowing the number of joints, it is easy to determine the required volume of steel wire.
How to calculate reinforcement for a columnar structure foundation
Columnar type foundation is widely used for the construction of various buildings. It consists of reinforced concrete supports of square and round cross-section, installed in the corners of the building, as well as at the intersection points of the main walls and internal partitions. To increase the strength of the supporting elements, ribbed rods with a cross section of 1–1.2 cm are used.
It is easy to calculate the amount of reinforcement for a columnar foundation, taking into account the following data:
- the frame of the square profile support element is formed from 4 rods;
- the lattice of a reinforced concrete support with a circular cross-section is made of three rods;
- the length of the reinforcement elements corresponds to the dimensions of the supporting column;
- The transverse piping of the support column frame is carried out in increments of 0.4–0.5 m.
Algorithm for calculating the consumption of foundation reinforcement
Calculation algorithm:
- Determine the length of the vertical bars in one support.
- Calculate the footage of the cross-bracing elements of one frame.
- Calculate the total length by adding the resulting values.
Multiplying the result by the number of supports, we get the total length of the reinforcement.
How to calculate reinforcement for a foundation - example calculations
As an example, let's consider how much reinforcement is needed for a 10x10 foundation formed in the form of a monolithic reinforced concrete strip.
To perform calculations we use the following information:
- base width 60 cm, allows you to lay 3 horizontal rods in each belt;
- 2 reinforcement belts are made, connected by vertical rods at intervals of 1 m.
- for a building 10x10 m and a base depth of 0.8 m, reinforcement with a diameter of 10 mm is used.
Consumption of reinforcement for strip foundations
Calculation algorithm:
- We determine the perimeter of the building’s foundation by adding the length of the walls - (10+10)x2=40 m.
- We calculate the number of horizontal elements in one belt by multiplying the perimeter by the number of rods in one tier - 40x3 = 120 m.
- The total length of the longitudinal bars is determined by multiplying the resulting value by the number of tiers 120x2=240 m.
- We calculate the number of vertical elements installed 10 pairs on each side 10x2x4 = 80 pcs.
- The total length of the vertical rods will be 80x0.8=64 m.
- We determine the length of the jumpers, each measuring 0.6 m, installed on two belts (20 per side) - 10x2x4x0.6 = 48 m.
- Adding the length of the reinforcing bars, we get a total footage of 240+64+48=352 m.
Determining the length of steel wire is easy. The number of connections multiplied by the length of one piece of wire equal to 20–30 cm will give the desired result.
Let's summarize - how necessary is the calculation of reinforcement for the foundation?
When planning the construction of a house, bathhouse or country house, it is easy to determine the need for fittings with your own hands.
Step-by-step instructions will allow you to use a calculator to calculate the footage of the rods for the manufacture of a reinforcing grid that strengthens the base of the building. Knowing how to calculate reinforcement, you can perform the calculations yourself without resorting to the help of third-party specialists.
Correctly performed calculations will ensure the strength of the foundation, the stability of the building, as well as a long service life.
Source: https://svaimania.ru/drenazh/diametr-armatury-dlya-lentochnogo-fundamenta-primer-uproshhennogo-rascheta.html
How to calculate reinforcement for a foundation
The service life, reliability and stability of any structure depends on the strength of its foundation. Calculation of foundations and underlying soil foundations is a rather complex construction science. On an industrial scale, accurate calculations of foundations are of great economic importance and help prevent excess consumption of cement and reinforcement.
The width of the foundation must be calculated in accordance with the load that the soil foundation can withstand, the required percentage of reinforcement is determined and, in accordance with the assortment, the reinforcing bars and their number are selected, the reinforcement cage is designed.
Why do you need foundation reinforcement?
It is known that stone structures (which include concrete - artificial stone) withstand compressive loads well, but easily break when stretched or bent. The main load experienced by the foundation is central compression.
The question may arise: why do you need to reinforce the foundation at all, if concrete copes well with the loads acting on it even without reinforcement? This is exactly what builders reasoned at the beginning of the last century.
As a result, many buildings from those times of construction have defects in the form of gaping cracks in the walls and distortions.
Some of these buildings can no longer be restored and must be demolished. And all this in most cases is due to improperly executed foundations. Do not forget that the patent for reinforced concrete was received in France by J.
Monier in 1867, and the use of reinforced concrete structures in construction began from the beginning of the 20th century, and its widest distribution began in the war (for the creation of fortifications) and the post-war period (for the accelerated restoration and reconstruction of what was destroyed during the war).
It turned out that reinforcing foundations can significantly reduce the consumption of materials, make them stronger and more reliable, and withstand bending loads that occur during frost heaving of the soil (when the soil freezes, it increases in volume due to the water contained in it), during a sudden rise in groundwater or emergency leaks in utilities in subsidence soils that tend to sharply lose their bearing capacity when soaked.
For an individual house, you can, of course, contact a specialized construction organization, whose specialists, having carried out all the research and calculations, will issue a draft of the most optimal foundation for the given structure. However, the cost of such a project will be comparable to the cost of manufacturing the foundation itself.
Several decades of widespread construction of private residential buildings have made it possible to develop methods for making foundations that make it possible to calculate the need for concrete and reinforcement, suitable for most individual developers from different regions. In this case, the foundations are stronger than necessary, and some excess consumption of concrete and reinforcement is allowed. Moreover, the cost of overused materials is much less than the cost of special design work.
Calculation of reinforcement for strip foundations
For individual construction, strip foundations are most common. How to calculate the amount of reinforcement for a foundation of this type?
For example, consider the construction of a two-story house measuring 12,000 x 12,000 mm (12 x 12 m) with two intersecting internal load-bearing walls spaced from the external walls at a distance of 6,000 mm (which corresponds to a building module of 6 meters).
The thickness of the external walls is 510 mm (two bricks), the thickness of the internal walls is 390 mm (one and a half bricks).
Assuming that the freezing depth in the area of proposed construction is 1200 mm (1.20 m), we choose the height of the underground part - 1500 mm, and the above-ground (basement) - 700 mm.
The total height of the foundation will be 1500 + 700 = 2200 mm.
The thickness of the foundation of the external walls, which should be 50 mm wider than the wall on each side, is taken to be 510 (wall thickness) + 2 x 50 = 610 mm, the thickness of the foundation of the internal walls is 490 mm.
Now let's see how to calculate the amount of reinforcement for the foundation. As reinforcement we will use rods with a periodic profile. A-III d (diameter) equal to 16 mm - for working reinforcement and rods d = 14 mm - for additional.
For clamps we use ordinary wire class. A-III d = 6 mm.
The distance from the reinforcement to the outer surfaces of the foundation (thickness of the protective layer) will be taken as 20 mm.
At the bottom of the foundation there will be three working reinforcing bars d = 16 mm with a distance from the central rod to the outermost 285 mm for external walls or d = 14 mm with a distance from the central rod to the outermost 225 mm for internal walls.
At a height of 700 mm and 1400 mm, respectively, there will be two rows of 2 rods of additional reinforcement d = 14 mm at a horizontal distance between them of 596 mm.
In the upper part of the foundation we will install 3 additional reinforcement rods d = 14 mm at a distance from the central rod to the outermost 230 mm for external walls and 220 mm, respectively, for internal ones.
If you mentally make a cross-section in the foundation of the outer wall, you can find 3 rods d = 16 mm and 7 rods d = 14 mm, in the section of the foundation of the inner wall - 10 rods d = 14 mm.
All these rods must be connected using bent clamps. This is a closed four-sided loop made of wire d = 6 mm. The clamp installation step is 600 mm in the transverse planes of the foundation. The clamps, together with the reinforcement bars, form a calculated spatial frame. You can make clamps using a template, the easiest way to make which is to drive four pieces of reinforcement into the ground at the required distance and bend a wire clamp of the required size around them.
The clamps and reinforcing bars must be tied together with annealed steel or so-called binding wire d = 1.4 mm. Electric arc and electric welding are not allowed, as the metal at the joints will be weakened.
If it is not possible to purchase working and additional reinforcement rods of the required length, the rods can be joined either with an overlap, the overlap length should be from 150 mm, or with the help of an additional rod 300 mm long, superimposed on the reinforcement rods connected end-to-end. Any type of joint is tightly wrapped with binding wire.
To ensure that the resulting reinforcement frame does not deform inside the formwork due to its own weight or during concreting, braces should be made from tying wire, connecting them to the formwork so that this does not interfere with pouring concrete.
For one clamp for external walls you will need: [1700 (foundation height) + 610 (width)] x 2 – 4 x 20 (concrete protective layer) = 4540 mm of wire d = 6 mm.
For internal walls (1700 + 490) x 2 – 4 x 20 = 4300 mm of the same wire.
For one external wall you will need 3 rods d = 16 mm long 12000 (wall length) - 2 x 20 (concrete protective layer on each side) = 11060 mm, 7 rods d = 14 mm of the same length and 21 clamps for one internal wall respectively, 10 rods d = 14 mm, the number of clamps will remain the same.
To tie clamps and reinforcing bars with knitting wire you will need - 10 (ties) x 500 (length per tie) = 5000 mm.
For four external walls
Reinforcing bars d = 16 mm – 11060 x 3 x 4 = 132720 mm (133 m).
Reinforcing bars d = 14 mm – 11060 x 7 x 4 = 309680 mm (310 m).
Wire d = 6 mm - 4540 x 21 x 4 = 381360 mm (382 m).
Knitting wire – 21 x 4 x 5000 mm = 420000 mm (420 m).
The reinforcement of the foundation of the internal walls will differ in that instead of reinforcement d = 16 mm, reinforcement d = 14 mm is used, as well as in the size of the clamps.
Reinforcement consumption for four internal walls
Reinforcing bars d = 14 mm – 11060 x 10 x 4 = 442400 mm (443 m).
Wire d = 6 mm – 4300 x 21 x 4 = 361200 mm (362 m).
Knitting wire – 21 x 4 x 5000 mm = 420000 mm (420 m).
We use assortment
The weight of one linear meter of reinforcement d = 16 mm is 1.578 kg.
Required 133 meters, weight - 133 x 1.578 = 210 kg.
The weight of one linear meter of reinforcement d = 14 mm is 1.208 kg.
Required 310 + 443 = 753 meters, weight – 753 x 1.208 = 910 kg.
The weight of one linear meter of wire d = 6 mm is 0.222 kg.
Required 382 + 362 = 744 meters, weight – 744 x 0.222 = 165 kg.
The weight of one linear meter of knitting wire d = 1.4 mm is 0.012 kg.
Required 420 x 2 = 840 meters, weight – 840 x 0.012 = 10 kg.
Conclusion
Additional information in the video about the process of foundation reinforcement
Source: http://obrawa.ru/kak-pravilno-rasschitat-armaturu-na-fundament/
Calculation of reinforcement for a strip foundation of a private house
Many believe that the cross-section and number of metal rods in the laid foundation does not play a special role, and they use everything that comes to hand, from knitting wire to metal pipes. But such connivance can have a bad impact in the future, both for the foundation itself and for the house standing on it.
In order for your future home to serve you for many years, it is necessary that the foundation of this house be strong enough and durable, and the correct calculation of the reinforcement for the foundation plays a huge role in this.
Calculating reinforcement for a strip foundation of a private house is not as complicated as it seems at first glance, and comes down to just determining the required diameter of the reinforcement and its quantity.
Strip foundation reinforcement scheme
To correctly calculate the reinforcement in a reinforced concrete strip, it is necessary to consider typical reinforcement schemes for strip foundations.
For private low-rise buildings, two reinforcement schemes are mainly used:
- four rods
- six rods
Which reinforcement scheme to choose? Everything is very simple:
And so, depending on the width of the strip foundation, we have chosen a reinforcement scheme; now we need to select the diameter of the reinforcement.
Calculation of the diameter of transverse and vertical reinforcement
The diameter of transverse and vertical reinforcement must be selected according to the table:
In the construction of one- or two-story private houses, as a rule, rods with a diameter of 8 mm are used as vertical and transverse reinforcement, and this is usually quite sufficient for strip foundations of low-rise private buildings.
Calculation of the diameter of longitudinal reinforcement
According to SNiP 52-01-2003, the minimum cross-sectional area of longitudinal reinforcement in a strip foundation should be 0.1% of the total cross-section of the reinforced concrete strip. This rule must be taken as a starting point when choosing the diameter of the reinforcement for the foundation.
Everything is clear with the cross-sectional area of the reinforced concrete strip; it is necessary to multiply the width of the foundation by its height, i.e. Let's say your tape width is 40 cm and the height is 100 cm (1 m), then the cross-sectional area will be 4000 cm2 .
The cross-sectional area of the reinforcement should be 0.1% of the cross-sectional area of the foundation, so the resulting area is 4000 cm2 / 1000 = 4cm2 .
In order not to calculate the cross-sectional area of each reinforcement rod, you can use a simple plate. Using it you can easily select the required diameter of the reinforcement for the foundation.
There are very minor inaccuracies in the table due to rounding of numbers, please ignore them.
Important: If the length of the tape is less than 3 m, the minimum diameter of the longitudinal reinforcement bars must be 10 mm.
When the length of the tape is more than 3 m, the minimum diameter of the longitudinal reinforcement should be 12 mm.
And so, we have a minimum calculated cross-sectional area of the reinforcement in the section of the strip foundation, which is equal to 4 cm2 (this takes into account the number of longitudinal rods).
With a foundation width of 40 cm, it is enough for us to use a reinforcement scheme with four rods. We return to the table and look in the column where the values for 4 reinforcement bars are given, and select the most suitable value.
Thus, we determine that for our foundation 40 cm wide, 1 m high, with a reinforcement scheme of four rods, the most suitable reinforcement with a diameter of 12 mm, since 4 rods of this diameter will have a cross-sectional area of 4.52 cm2.
Calculation of the diameter of the reinforcement for a frame with six bars is carried out in a similar way, only the values are already taken from the column with six bars.
Calculation of the amount of reinforcement for the foundation
It often happens that the reinforcement was brought to the construction site, and when they begin to knit the frame, it turns out that it is missing. You have to buy more and pay for delivery, and these are additional expenses that are not at all desirable in the construction of a private house.
To prevent this from happening, it is necessary to correctly calculate the amount of reinforcement for the foundation.
Let's say we have the following foundation diagram:
Let's try to calculate the amount of reinforcement for such a strip foundation.
Calculation of the amount of longitudinal reinforcement
In order to calculate the required amount of longitudinal reinforcement for the foundation, you can use a rough calculation.
First you need to find the length of all the foundation walls, in our case it will be:
6 * 3 + 12 * 2 = 42 m
Since we have a 4-rod reinforcement scheme, we need to multiply the resulting value by 4:
42 * 4 = 168 m
We have obtained the length of all longitudinal reinforcement bars, but do not forget that:
When calculating the amount of longitudinal reinforcement, it is necessary to take into account the launch of the reinforcement during joining, because it very often happens that the reinforcement is delivered to a section of a 4-6 m long rod, and in order to get the required 12 m, we will have to join several rods. The reinforcement bars must be joined with an overlap, as shown in the diagram below; the start of the reinforcement must be at least 30 diameters, i.e. when using fittings with a diameter of 12 mm, the minimum launch should be 12 * 30 = 360 mm (36 cm).
In order to take this launch into account, there are two ways:
- Draw up a diagram of the arrangement of rods and calculate the number of such joints
- Add about 10-15% to the resulting figure, as a rule, this is enough.
Let's use the second option and in order to calculate the amount of longitudinal reinforcement for the foundation, we need to add 10% to 168 m:
168 + 168 * 0.1 = 184.8m
We have calculated the number of only longitudinal reinforcement with a diameter of 12 mm, now let's calculate the number of transverse and vertical rods in meters.
Calculation of the amount of transverse and vertical reinforcement for a strip foundation
To calculate the amount of transverse and vertical reinforcement, let us again turn to the diagram, from which it can be seen that it will take one “rectangle”:
0.35 * 2 + 0.90 * 2 = 2.5 m.
I specifically took with a margin not 0.3 and 0.8, but 0.35 and 0.90 so that the transverse and vertical reinforcement would extend slightly beyond the resulting rectangle.
Important: Very often, when assembling a frame in an already dug trench, vertical reinforcement is placed at the bottom of the trench, and sometimes it is also driven a little into the ground for better stability of the frame. So this will need to be taken into account, and then it will be necessary to take into account not the 0.9 m length of vertical reinforcement, but increase it by about 10-20 cm.
Now let's count the number of such “rectangles” in the entire frame, taking into account that there will be 2 such “rectangles” at the corners and at the junction of the walls of the strip foundation.
Let's first take the longest side (12 m) and count the amount of transverse and vertical reinforcement on it.
As you can see from the diagram, on the 12 m side we have 6 of our “rectangles” and two parts of the wall of 5.4 m each, on which another 10 lintels will be located.
Thus, we get:
6 + 10 + 10 = 26 pcs.
26 “rectangles” on one side of 12 m. Similarly, we count the lintels on a 6 m wall and find that there will be 10 lintels on one six-meter strip foundation wall.
Since we have two 12-meter walls, and 3 6-meter walls, then
26 * 2 + 10 * 3 = 82 pieces.
Remember, according to our calculations, each rectangle had 2.5 m of reinforcement:
2.5 * 82 = 205 m.
Final calculation of the amount of reinforcement
We determined that we need longitudinal reinforcement with a diameter of 12 mm, and transverse and vertical reinforcement will have a diameter of 8 mm.
From previous calculations, we found out that we need 184.8 m of longitudinal reinforcement, and 205 m of transverse and vertical reinforcement.
Following the above rule, we need to buy 190-200 m of reinforcement with a diameter of 12 mm and 210-220 m of reinforcement with a diameter of 8 mm.
If the reinforcement remains, don’t worry, you will need it more than once during the construction process.
Source: http://postroj-sam.ru/fundament-doma/raschet-armatury-dlya-lentochnogo-fundamenta-chastnogo-doma.html
How to calculate the amount of reinforcement for a strip foundation?
The construction of the foundation of a building under construction requires the solution of such a problem as calculating the reinforcement for a strip foundation necessary for constructing a frame. To resolve the issue, it is necessary to understand the purpose of the metal frame in concrete structures. Be able to design a strip foundation taking into account the effects of loads at the limit state of the structure. Know how calculations are performed and the frame is formed.
It is important to immediately decide on the quantity of reinforcement of one class or another and calculate the cost. The task is not easy, but doable even with independent design.
Why do you need fittings?
The use of reinforcement when installing a monolithic strip foundation turns concrete into a qualitatively new material - reinforced concrete. Concrete itself has a lattice structure at the nodes of which there are solid fractions of crushed stone or gravel, it has high compressive strength and low tensile strength.
When a distributed load is applied to a concrete beam, designed to be rigidly clamped at both ends, it bends.
In this case, the bottom of the beam works in bending, the top in compression, and vice versa when the soil is heaving. An example of frame calculation is given below.
To increase structural rigidity and stability, a frame made of metal or fiberglass (composite) reinforcement of the design diameter is installed inside the monolithic structure. The result is a reinforced concrete structure with high compression and tension characteristics.
Formation of frames in strip foundations
Working reinforcement is installed along the top and bottom of the frame (it is assumed that the middle layer is not deformed), and works in the beam together with concrete. When the limiting states of concrete for bending are reached, the reinforcement is included in independent work to maintain the structure in its design condition and position.
How to calculate the diameter and quantity of reinforcement
The quantity of reinforcement required for installation of rows of reinforcement, diameter and class is calculated at the drafting stage of the project and is indicated in the calculation part of the explanatory note. A full calculation of the foundation and frame requires professional knowledge, the ability to understand topics on foundations and foundations, structural mechanics, and correctly interpret the provisions of SNiP.
A complete correct calculation of frame reinforcement is carried out during the construction of class 1 structures according to engineering geological survey reports. During individual construction of a house with a 2-3 class of responsibility, reinforcement is assigned structurally, taking into account the requirements of SP 52-101-2003.
Using an online calculator
For those who trust themselves in solving this complex and important decision, it is recommended to use online calculators that are used for free on the appropriate services. Calculators are of the same type, with minimal requirements for questions for the database:
- The type of foundation is indicated. To do this, you need to choose one that is approximately similar to the design one from 5 options. On the site, it is possible to more accurately select the type of foundation, removing walls from the proposed extended option, changing the geometric location, getting closer to the project. The walls are removed by assigning a zero size.
- Select the grade of concrete for the strip foundation from the drop-down list.
- The total length of the foundation, including partitions (meters), is entered in the field.
- Enter the height and width of the tape in the appropriate fields (centimeters).
- Check the box next to “calculate reinforcement”. Choose whether there is concrete preparation or not. From the list, indicate in the field the length of the metal assortment that is sold at the wholesale warehouse, select the minimum cross-section of the load-bearing reinforcement.
This is what the online calculator looks like on the display:
- If you need to calculate the number of boards, check the box next to “formwork calculation” and enter the length, width, and thickness of the boards that are supposed to be used for formwork in the appropriate fields.
- Click on the "Calculate" button.
As a result, the calculator will make calculations and display the obtained data in the form of tables. The authors of the calculators claim that the program algorithm is based on the provisions and formulas of SP 52-101-2003, SNiP 3.03.01-87.
Report on foundations Report on the required number of boards for formwork This is what a report on frame metal looks like.
Self-calculation
As an option, calculate the amount of reinforcement, cross-section, and location on your own. The reinforcement must be assigned structurally.
Use the provisions of SP 52-101-2003: when calculating foundations based on the natural bearing capacity of soils and the limiting states of concrete structures for bending, take the minimum amount of the total cross-sectional area of working reinforcement equal to 0.001-0.005% of the cross-sectional area of the foundation. For strip foundations, it is recommended to use a coefficient of 0.oo2%.
An example and calculation algorithm looks like this:
- Select the height and width of the foundation in the project. Calculate the area. If the dimensions along the external and internal axes are different, calculate the sections separately to obtain the most reliable data on the reinforcement. For example: foundation height = 1200 mm, width = 400 mm. Area = 480,000 mm2.
- According to the position of the joint venture, we accept the constructively minimum cross-sectional area of the working reinforcement depending on the cross-sectional area for the strip foundation: 480 oo mm2 * 0.002 = 960 mm2.
- According to the table of sections, depending on the diameter of the reinforcement, we find: 4 rods of class A 400 (GOST 5781-82) with a diameter of 18 mm or 4 fiberglass rods with a diameter of 16 mm (GOST 31938-2011) are suitable from the conditions of equal strength of composite and steel products. If the foundation sections along the axes are different, calculate the reinforcement separately.
- Further calculation of how much metal is needed completely depends on the perimeter of the foundation along the axes.
When calculating the amount of working reinforcement and frame piping, it is necessary to take into account the provisions of SP 52-101-2003:
- The minimum protective layer of concrete for a metal frame = 40 mm or 50 mm for chemically aggressive soils (Table 1).
- The minimum distance between the working bars of the reinforcement cage along the lower chord = 25 mm, along the upper chord = 30 mm (clause 8.3.3).
- The length of the bypasses when joining for A 400 and A 250 is at least 250 mm. In one section, no more than 50% of the joints of working reinforcement and 25% of smooth structural reinforcement A 250 (clause 8.3.27).
Source: https://fasad-prosto.ru/fundament/raschet-armatury-dlya-lentochnogo-fundamenta.html
Strip foundation reinforcement
Calculator Reinforcement-Tapes-Online v.1.0
Calculation of longitudinal working, structural and transverse reinforcement for strip foundations. The calculator is based on SP 52-101-2003 (SNiP 52-01-2003, SNiP 2.03.01-84), Manual for SP 52-101-2003, Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete (without prestressing) .
If this menu item is selected, the calculator will calculate the minimum content of working longitudinal reinforcement for the foundation structure in accordance with SP 52-101-2003. The minimum percentage of reinforcement for reinforced concrete products lies in the range of 0.1-0.25% of the cross-sectional area of the concrete, equal to the product of the width of the tape and the working height of the tape.
SP 52-101-2003 Clause 8.3.4 (analogous to the Manual for SP 52-101-2003 Clause 5.11, Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, clause 3.8)
Manual to SP 52-101-2003 Clause 5.11
In our case, the minimum percentage of reinforcement will be 0.1% for the tension zone. Due to the fact that in a strip foundation the stretched zone can be both the top and bottom of the strip, the percentage of reinforcement will be 0.1% for the top chord and 0.1% for the bottom chord of the strip.
For longitudinal working reinforcement, rods with a diameter of 10-40 mm are used. For the foundation, it is recommended to use rods with a diameter of 12 mm.
Manual to SP 52-101-2003 Clause 5.17
Guidelines for the design of concrete and reinforced concrete products made of heavy concrete, paragraph 3.11
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, paragraph 3.27
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, paragraph 3.94
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, paragraph 3.94
Distance between rods of longitudinal working reinforcement
Manual to SP 52-101-2003 Clause 5.13 (SP 52-101-2003 Clause 8.3.6)
Manual to SP 52-101-2003 Clause 5.14 (SP 52-101-2003 Clause 8.3.7)
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, paragraph 3.95
Structural reinforcement (anti-shrinkage)
According to the manual for the design of concrete and reinforced concrete structures made of heavy concrete, paragraph 3.104 (analogous to the Manual for SP 52-101-2003, paragraph 5.
16) for beams with a height of more than 700 mm, structural reinforcement is provided on the side surfaces (2 reinforcement bars in one horizontal row). The distance between the structural reinforcement bars in height should be no more than 400 mm.
The cross-sectional area of one reinforcement must be at least 0.1% of the cross-sectional area, equal in height to the distance between these rods, half the width of the tape in width, but not more than 200 mm.
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, paragraph 3.104 (Manual to SP 52-101-2003, paragraph 5.16)
According to calculations, it turns out that the maximum diameter of the structural reinforcement will be 12 mm. According to the calculator, it may turn out to be less (8-10mm), but still, in order to have a margin of safety, it is better to use reinforcement with a diameter of 12mm.
Example
Initial data:
- Foundation dimensions in plan: 10x10m (+one load-bearing internal wall)
- Tape width: 0.4m (400mm)
- Tape height: 1m (1000mm)
- Concrete cover: 50mm (selected by default)
- Reinforcement diameter: 12mm
Calculation:
Working height of the tape section [ho] = Tape height – (Protective layer of concrete + 0.5 * Diameter of working reinforcement) = 1000 – (50 + 0.5 * 12) = 944 mm
Sectional area of the working reinforcement for the lower (upper) chord = (Tape width * Working height of the tape section) * 0.001 = (400 * 944) * 0.001 = 378 mm2
We select the number of rods according to SP 52-101-2003 Appendix 1.
We select a section greater than or equal to the section found above.
The result was 4 reinforcement bars with a diameter of 12 mm (4F12 A III) with a cross-sectional area of 452 mm.
So, we have found rods for one belt of our tape (let's say the bottom one). For the top one it will be the same. Eventually:
Number of rods on the bottom belt of the tape: 4
Number of rods on the upper belt belt: 4
Total number of longitudinal working rods: 8
Total cross-section of longitudinal working reinforcement per strip = Cross-section of one rod * Total number of longitudinal rods = 113.1 * 8 = 905mm2
Total length of the tape = Foundation length * 3 + Foundation width * 2 = 10 * 3 + 10 * 2 = 50m (47.6m in the calculator taking into account the width of the tape)
Total length of rods = Total length of tape * Total number of longitudinal rods = 47.6 * 8 = 400m = 381m
Total weight of reinforcement = Weight of one meter of reinforcement (we find it from the table above) * Total length of rods = 0.888 * 381 = 339 kg
Volume of reinforcement per strip = Section of one longitudinal reinforcement * Total length of rods / 1000000 = 113.1 * 381 / 1000000 = 0.04m3
Design reinforcement
If this type of menu is selected, then the calculation of the longitudinal working reinforcement for the tension zone will be performed according to the formulas of the manual to SP 52-101-2003.
In our case, tensile reinforcement is installed at the top and bottom of the tape, so we will have working reinforcement in both the compressed and tension zones.
Transverse reinforcement (clamps)
Transverse reinforcement is calculated based on user data.
Transverse reinforcement standards
Manual to SP 52-101-2003 Clause 5.18
Manual to SP 52-101-2003 Clause 5.21
Manual to SP 52-101-2003 Clause 5.21
Manual to SP 52-101-2003 Clause 5.23
Manual to SP 52-101-2003 Clause 5.20
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete. Paragraph 3.105
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete. Paragraph 3.106
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete. Paragraph 3.107
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete. Paragraph 3.109
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete. Paragraph 3.111
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete. Clause 2.14
Manual to SP 52-101-2003 Clause 5.24
Manual to SP 52-101-2003 Clause 5.22
Protective layer of concrete
Manual to SP 52-101-2003 Clause 5.6
Manual for SP 52-101-2003 Clause 5.8 (Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete, clause 3.4)
Useful
Regulatory documentation
SP 52-101-2003 Concrete and reinforced concrete structures without preliminary
reinforcement stresses Manual for SP 52-101-2003 on the design of concrete and reinforced concrete structures without preliminary
reinforcement stress SNiP 2.03.01-84 Concrete and reinforced concrete structures
Guidelines for the design of concrete and reinforced concrete structures made of heavy concrete (without prestressing)
Books
Reinforcement of elements of monolithic reinforced concrete buildings I.N. Tikhonov 2007
Construction calculators
Source: https://www.gvozdem.ru/stroim-dom/kalkulyatory/armirovanie-lentochnogo-fundamenta.php
Calculation of reinforcement for strip foundations, price
Before calculating the foundation reinforcement, it is necessary to determine the thickness of the foundation and its base. To calculate this, it is necessary to conduct geological research on the site and calculate the weight of the house with all loads. Since this is a rather large topic, we have included it in a separate article - calculating the weight of a house. Well, this review is specifically about calculating the reinforcement of a strip foundation.
Reinforcement schemes for strip foundations
The strip foundation absorbs the main bending load in the horizontal (longitudinal) plane. That is, the longitudinal bars of the reinforcement work in tension as much as possible. It is also worth clarifying that the workers in the foundation are the upper and lower rows of reinforcement.
For low-rise buildings, two working reinforcement schemes are used:
- Four working rods (two rods on top and two on bottom)
- Six rods (three on top and three on bottom)
Selecting the desired scheme is quite simple. According to SNiP, the distance between the working reinforcement rods in one row should not exceed 40 cm.
If we take into account the protective layer of concrete on each side of 5 cm, we get the following:
- Foundation up to 50 cm wide - scheme with four rods .
- Width from 50 to 90 cm - scheme with six rods .
Structural longitudinal rows of reinforcement
It is worth noting that if the height of the foundation strip is more than 70 cm, then it is necessary to add structural longitudinal rows of reinforcement; they are called anti-shrinkage rows and they help keep the frame in the correct position. The diameter of structural reinforcement bars is usually between 8 and 10 mm.
The number of structural longitudinal rows depends on the height of the tape. According to SNiP, the distance between structural rows of reinforcement should not exceed 40 cm.
Number of rows of structural reinforcement, depending on the height of the tape:
- Up to 70 cm - without structural longitudinal reinforcement.
- 71-90cm – 1 row of structural reinforcement
- 91-130 cm – 2 rows
- 131-170 cm – 3 rows.
- 171-210 cm – 4 rows.
Calculation of the diameter of longitudinal working reinforcement
The total cross-sectional area of the working longitudinal reinforcement must be at least 0.1% of the cross-sectional area of the foundation, that is, one thousandth of the cross-section of the foundation. The minimum diameter of working reinforcing bars is 12 mm.
Example: the height of the foundation strip is 100 cm, width is 40 cm.
- The cross-sectional area of the tape is 4000 cm2.
- We find the required cross-section of the working reinforcement - 4000/1000 = 4 cm2.
Next, according to the table, we select reinforcing bars of the required diameter, depending on the reinforcement scheme - 4 or 6 working bars.
In our case, these are 4 rods of 12th diameter, since in the table the closest suitable value is 4.52 cm (452 mm).
It is worth noting that the working rods of the longitudinal reinforcement must be of the same diameter, but if you do not have enough required reinforcement, then the thickest rods should be placed in the bottom row.
The overlap of the longitudinal reinforcement bars should be 40 diameters of the reinforcement, that is, 40 * 12 = 480 mm.
The distance between the clamps (rectangular frames) is 500 mm, and at the corners - 300 mm.
Calculation of the amount of reinforcement
For example, let's take a strip foundation with sides of 10 and 8 meters, with a central beam in the middle. The height of the tape is 1 meter, width is 40 cm. Reinforcement pattern of 4 working rods 12 mm.
- The length of the reinforcement rod is 11.7 meters.
- The total length of the tape is 10+10+8+8.4 = 43.4 m.
- The length of all bars of working longitudinal reinforcement is 43.4 x 4 = 173 m, + add 10 meters for overlaps, it comes out to 183 m.
- The length of the structural longitudinal will also be 183 m.
The clamps have the shape of a rectangle, and the perimeter of such a rectangle, taking into account the bends, will be: 90+90+35+35=250 cm.
- Since the distance between the clamps is 50 cm, we will need
- (43 x 2) + 4 = 90 clamps with a diameter of 8 mm.
- The total length of the reinforcement for the clamps is 90 x 2.5 = 225 meters.
- Number of horizontal transverse reinforcement bars – 90 x 2 =180
- The length of the horizontal transverse reinforcement bar is 30 cm, diameter is 8 mm. Total length – 180 x 0.3 = 54 m.
Don't forget about the protective layer of concrete - 5 cm!
Total number of fittings
- Working longitudinal reinforcement (12 mm) – 183 meters.
- Structural longitudinal reinforcement (8 mm) – 183 m.
- Rectangular clamps (8 mm) – 225 m.
- Horizontal transverse reinforcement (8 mm) – 54 m.
Since there will be remnants of reinforcement when cutting, you will have to add another 10% to the obtained values. All the same, the reinforcement is useful, for example, for reinforcing lintels, armored belts, aerated concrete walls and other things.
For our strip foundation you will need:
- 12 mm rods - 183 m + 10% = 200 m
- 8 mm rods - 420 m + 10% = 465 m
Calculation of the cost of reinforcement for the foundation, price
- The weight of a meter bar of reinforcement with a diameter of 8 mm = 0.395 kg.
- The weight of a linear meter of 12 mm rod is 0.888 kg.
- Let's calculate the total weight of the reinforcement - 0.395 x 465 + 0.888 x 200 = 362 kg.
- The approximate cost of a linear meter of 12 mm reinforcement is 50 rubles.
- The approximate cost of a meter of 8 mm reinforcement is 20 rubles.
- Total cost – 465 x 20 + 200 x 50 = 19,300 rubles
- Including knitting wire - 20,000 rubles.
Now you are familiar with how to calculate the approximate amount of reinforcement for a strip foundation.
Source: http://stroy-gazobeton.ru/82-raschet-armatury-dlya-lentochnogo-fundamenta-tsena
Calculation of reinforcement for strip, slab and pile foundations
Often in the process of preparing for construction, the question arises, what thickness of reinforcement is optimal? On the one hand, the correct calculation of the foundation reinforcement affects its strength, and therefore the reliability and durability of the entire structure. This is especially important considering the funds spent on construction. On the other hand, there is a natural desire not to overpay.
Professional builders, when calculating the parameters of foundation reinforcement, use the provisions of SNiP 52-01-2003 “Concrete and reinforced concrete structures”. In private construction, for calculations, it is more than enough to follow one single rule: in the cross-sectional area of a reinforced concrete structure, the share of the total area of all reinforcing rods should not be less than one thousandth (or 0.1%).
Although the wording may seem a little confusing, the rule is actually not difficult to use. For clarity, we will make, as examples, several practical calculations of the thickness and amount of reinforcement for strip, slab and pile foundations. In the calculations we will need some initial data, we will take them from the table below.
Table of cross-sectional area of reinforcement for reinforcing reinforced concrete structures
(GOST 5781-82)
| Rod diameter, mm. | Cross-sectional area of the rod, cm2 | Cross-sectional area of the rod, m2 |
| 6 | 0,283 | 0,0000283 |
| 8 | 0,503 | 0,0000503 |
| 10 | 0,785 | 0,0000785 |
| 12 | 1,131 | 0,0001131 |
| 14 | 1,540 | 0,000154 |
| 16 | 2,010 | 0,000201 |
| 18 | 2,540 | 0,000254 |
| 20 | 3,140 | 0,000314 |
| 22 | 3,800 | 0,000038 |
| 25 | 4,910 | 0,000491 |
| 28 | 6,160 | 0,000616 |
| 32 | 8,010 | 0,000801 |
| 36 | 10,180 | 0,001018 |
| 40 | 12,570 | 0,001257 |
| 45 | 15,000 | 0,0015 |
| 50 | 19,360 | 0,001936 |
| 55 | 23,760 | 0,002376 |
| 60 | 28,270 | 0,002827 |
| 70 | 38,480 | 0,003848 |
| 80 | 50,270 | 0,005027 |
Depending on the mechanical properties, reinforcing steel is divided into classes AI (A240), A-II (A300), A-III (A400), A-IV (A600), AV (A800), A-VI (A1000).
Reinforcing steel is manufactured in bars or coils. Reinforcing steel of class AI (A240) is made smooth, classes A-II (A300), A-III (A400), A-IV (A600), AV (A800) and A-VI (A1000) - periodic profile.
Strip foundation reinforcement
An example of calculating the reinforcement of a strip foundation
A strip foundation with the following section is designed:
- height 1.8 m;
- tape width 0.4 m.
It is necessary to calculate possible options for longitudinal reinforcement and select the optimal one.
Let's calculate the cross-sectional area of the foundation: 1.8 x 0.4 = 0.72 sq.m.
Minimum total cross-section of reinforcement: 0.72 / 1000 = 0.00072 sq. m.
Dividing the obtained value by the cross-sectional area of reinforcement of various diameters (from the table above), we obtain the minimum required number of veins. So for reinforcement with a diameter of 6 mm we have:
0.00072 / 0.0000285 = 25.30580079 pcs.
Rounding the resulting value up (for the safety margin), we get: in order to reinforce a foundation with given dimensions with “six” reinforcement, you will need to install 26 longitudinal rods. Of course - not the best engineering solution.
Continuing the calculation for other reinforcement diameters, we obtain the following options:
- for rods with a diameter of 6 mm - 26 pcs., by analogy below (mm and pcs are omitted):
- 8 — 15;
- 10 — 10;
- 12 — 7 ;
- 14 — 5 ;
- 16 — 4 ;
- 18 — 4 ;
- 20 — 3 ;
- 22 — 3 ;
- 25 — 2 ;
- 28 — 2 ;
- 32 — 2 ;
- 36 — 1 ;
- 40 — 1 .
It is easy to see that “our” options are reinforcement bars with a diameter of 16 or 18 mm. 4 of them are required for the foundation - two each for the lower and upper tiers.
Slab foundation reinforcement
An example of calculating the reinforcement of a slab foundation
A slab foundation is being designed for a building 8 by 5 meters. The thickness of the slab is 35 cm. The owner has at his disposal fittings with a diameter of 10 mm. It is necessary to determine the parameters of the reinforcement structure.
Cross section. Let's determine its area: 8.0 x 0.35 = 2.8 square meters.
Minimum total cross-section of reinforcement: 2.8 / 1000 = 0.0028 sq.m.
Number of veins: 0.0028 / 0.000079 = 35.5 = 36 pieces
(18 in the top layer and 18 in the bottom).
In total, in the transverse direction, the upper and lower layers each contain 18 reinforcement bars.
Longitudinal section. Let's determine its area: 8.0 x 0.35 = 1.75 square meters.
Minimum total cross-section of reinforcement: 1.75 / 1000 = 0.00175 sq.m.
Number of veins: 0.00175 / 0.000079 = 22.2 = 23 pieces, accept 24 pieces. (12 in the top layer and 12 in the bottom).
In total, in the transverse direction, the upper and lower layers each contain 12 reinforcement bars.
Pile foundation reinforcement
An example of calculating the reinforcement of a pile foundation
Let us determine the most optimal and cost-effective method of reinforcing cast-in-place piles of circular cross-section with a diameter of 20 cm (0.2 m).
Let's determine the cross-sectional area of the pile:
Source: https://VolgaProekt.ru/stati/raschet-armirovaniya-fundamenta.html
Online strip foundation calculator: calculation of reinforcement, concrete, formwork
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 building, 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.
Source: https://calcstroy.ru/fundament/lentochnyj-fundament
Calculation of reinforcement for the foundation
Calculation of reinforcement for a foundation is an important stage in its design, so it must be carried out taking into account the requirements of SNiP 52-01-2003 for choosing the class of reinforcement, cross-section and its required quantity.
First you need to understand why metal reinforcement is needed in a monolithic concrete foundation. Concrete, after gaining industrial strength, is distinguished by high compressive strength and significantly lower tensile strength. An unreinforced concrete base is prone to cracking when the soil swells, which can lead to deformation of the walls and even destruction of the entire building.
Calculation of reinforcement for the foundation
Calculation of reinforcement for a slab foundation
Slab foundations are often used in the construction of cottages and country houses, as well as other buildings without a basement. It is a concrete slab reinforced with rods in both perpendicular directions; when the foundation thickness is more than 20 cm, the mesh is made in the upper and lower layers.
Before starting the calculation, it is necessary to decide on the brand of reinforcing bar.
For slab foundations built on strong, non-heaving soils, where the likelihood of horizontal shift of the building is negligible, it is allowed to use class AI ribbed reinforcing bars with a diameter of 10 mm or more.
If the soil is weak, heaving, or the building is on a slope, a rod must be selected at least 14 mm in diameter. For vertical connections between the lower and upper reinforcing mesh, a smooth rod with a diameter of 6 mm of class AI is sufficient.
The material of the walls also matters, since the load of the building differs significantly between frame or wooden houses and buildings made of brick or aerated concrete blocks. In general, for light small buildings it is allowed to use a rod with a diameter of 10-12 mm, for brick or block - reinforcement 14-16 mm in diameter.
The distances between the rods in the mesh are usually 20 cm in both the longitudinal and transverse directions. This means that 5 reinforcing bars must be laid per 1 meter of house length. Perpendicular intersecting rods are tied together with soft annealed wire using a crochet hook or a knitting gun.
Sample of installed foundation reinforcement
Calculation example
The house is made of aerated concrete blocks, installed on a slab foundation 40 cm thick on medium-heaving loam. The overall dimensions of the house are 9x6 meters.
- Since the thickness of the foundation is significant, two reinforcement meshes are needed, as well as vertical connections. Horizontal meshes for block structures on medium-heaving soil are made from reinforced rods with a diameter of 16 mm, and vertical meshes are made from smooth rods with a diameter of 6 mm.
- The number of longitudinal reinforcement bars is calculated as follows: the length of the larger side of the foundation is divided by the lattice pitch: 9/0.2 = 45 longitudinal reinforcing bars 6 meters long, and the total number of bars is 45 6 = 270 m.
- Similarly, find the number of rods for cross braces: 6/0.2 = 30 rods; 30·9 = 270 m.
- The total number of bars for two reinforcing meshes is: (270+270) 2 = 1080 m.
- Vertical ties have a length equal to the height of the foundation. Their number is determined by the number of intersections of longitudinal and transverse reinforcing bars: 45·30 = 1350 pieces. Their total length is 1350·0.4 = 540 meters.
- Thus, to complete the foundation it is necessary:
- 1080 meters of rod class A-III D16;
- 540 meters of AI D6 class rod.
- According to GOST 2590 we find its mass. A linear meter of D16 rod weighs 1.58 kg; meter of bar D6 – 0.222 kg. We calculate the total mass: 1080·1.58 = 1706.4 kg; 540·0.222 = 119.88 kg.
Total cross-sectional area of reinforcement bars
- The calculation of the binding wire depends on the tool used. When crocheting, the average wire consumption is 40 cm per connection. The number of connections in one row is 1350, in two – 2700. The wire consumption will be 2700·0.4 = 1080 meters. The mass of 1 meter of wire with a diameter d=1.0 mm is 6.12 g. To tie the foundation reinforcement you will need 1080·6.12 = 6610 g = 6.6 kg of wire.
