Reinforcement technology helps to achieve optimal building strength in modern construction. The ways of its implementation are diverse and the choice of a specific one depends on a number of parameters of the object being strengthened. Reinforcement is most widely used as a foundation element - it is thanks to metal rods that a high-strength building component called reinforced concrete is formed. At the same time, the integration of the rods into the concrete base must be strictly calculated, otherwise all efforts to create a reliable platform will be in vain.
Parameters for reinforcement design
Calculation of the volume and parameters of the metal "skeleton" is impossible without knowledge of the required properties relative to the building itself. Based on its characteristics, reinforcement for the foundation is selected. The calculation is made according to several indicators that determine the technical and operational qualities of the building.
The list of base values includes the following parameters:
- mass of rods used;
- length of each element;
- total frame weight;
- diameter and ribbing;
- number of rods.
It would seem that the applicationthe maximum possible amount of reinforcement will achieve the highest technical and operational qualities of the building foundation. But this is not the case, since improper distribution of loads on the foundation can have the opposite effect, weakening the structure.
Calculation for slab foundation
One of the most popular types of foundation is slab. In this case, ribbed rods with a diameter of at least 1 cm are used. The choice of thickness depends on the planned mass of the house and the characteristics of the soil. For example, if a wooden structure is being erected, then the calculation of reinforcement for a slab foundation may assume a minimum allowable thickness. In the case of a stone or brick house, this figure is on average 1.5 cm. Based on these data, the optimal amount of reinforcing material is selected.
Step of reinforcing mesh
The number of rods, as well as their standard size, must be calculated according to the grid step. So, if reinforcement is planned on a 6x6 m slab foundation, then the gap will be 20 cm. That is, it will be necessary to install 31 rods along and across. Accordingly, the calculation of the amount of reinforcement for the foundation in this case shows the need to use 62 rods. But that's not all - since two belts are formed at the plate, the primary result is multiplied by two - as a result, 124 units are obtained. The total length of the material, provided that one rod has a length of 6 m, will be 744 m.
You will also need connecting fittings. It is calculated individually and based on the widthbelts are connecting rods a few decimeters long. In the case of the described foundation, the total length of the auxiliary reinforcement will be about 100 m.
Calculation for strip foundation
When constructing a tape base for a house, reinforcement with a diameter of 10-14 mm is also used. But there is one difference that determines the specifics of the consumption of rods in such foundations. The fact is that the tape-type concrete structure is more resistant to bending, so the thickness will initially be underestimated when compared with the slab counterpart.
A3 brand rods are used for longitudinal reinforcement. Their function is to receive a direct load on the foundation, which determines the need to use rods with a ribbed surface. Less high loads fall on vertical and transverse elements, so they can be smooth - grade A1. Usually, the calculation of reinforcement for a strip foundation involves the installation of four rods in the longitudinal direction - two for each chord. If the requirements for reliability increase due to the instability of the soil or the characteristics of the building itself, then an increase in the number of rods is possible.
Calculation for column foundation
This type of foundation involves the use of reinforcing rods with the smallest thickness - a diameter of 1–1.2 cm is common.) perform only the function of a bundle.
Bas an illustration of the fortification, you can take a column 2 m long and 40 cm in diameter. Here you will need four elements with a diameter of 1.2 cm, between which a step of 20 cm is maintained. Their fastening will be performed by smooth rods with a diameter of 6 mm. Regarding the length, the calculation of the reinforcement of a columnar foundation can be represented as follows: four vertical bars of 2 m each will total 8 m.
Reinforcement schemes
The shape of the metal frame in the concrete base depends on the chosen reinforcement scheme. The latter, in turn, will determine the effectiveness of the applied configuration - in each case it may be different.
The main rule in choosing a scheme for forming a structure from metal rods is a bias towards the correct forms. The installation of reinforcement elements in the form of a rectangle or square, as practice shows, provides the highest reliability to the building. However, other solutions for the construction of a reinforcing frame are not excluded if the project of the house itself deviates from the standards.
The layout of the bars in a concrete structure must also take into account additional reinforcement, which, however, is not so necessary if a slab foundation is being built. The calculation of reinforcement with reinforcement is usually used in strip reinforced concrete foundations when corners and joints are formed.
Fixing reinforcement
Even the correct calculation of the reinforcement will not ensure the reliability and durability of the foundation if an unsuccessful method of fixing the rods is chosen. Usually used to connect metal structures and parts.welding, but in the case of reinforcement, it is advisable to focus on wire fastening - the structure of the material will retain its original qualities, reliably strengthening the concrete.
For this, knitting wire and a special hook are used to create knots. Optimal frame strength is possible only with a uniform connection of the convergence sections of the rods - exceptions apply to corner sections that require reinforcement. Additional reinforced reinforcement for the foundation, the calculation of which takes into account the "problematic" places of joints and turns, will protect the structure from physical impacts.
On average, about 25 cm of knitting wire is consumed for each joint. You can increase the reliability of the nodal connection by double tying, and then using a knitting hook.
Errors in reinforcement
The best way to insure against incorrect selection and installation of fittings is to follow the design documentation steadily. Ignoring the established construction parameters may be due to the desire to save money, the lack of the necessary material, etc. Each of these cases poses a risk to the safety of the facility under construction. It is also not recommended to forget about the technological rules by which reinforcement for the foundation is selected. Calculating it will optimize further laying, but the main contribution to the success of the project will be made by the primary quality of the material.
In addition, in the organization and reinforcement itselfthe following errors should be prevented:
- The use of fittings that do not match the characteristics. Smooth rods cannot replace analogues with a ribbed surface, as well as one category of material - another.
- Unprepared metal surface. The presence of grease, corrosion and dirt is unacceptable, as it reduces the adhesive qualities of the material.
- Errors in the calculation of gaps, according to which reinforcement for the foundation is laid. The calculation of the step from one rod to another should not be less than 2 cm - this is unjustified from the point of view of the reliability of the structure and the proportional distribution of loads.
- Connection of reinforcement in places of tension of the concrete base. If there is not enough length of the reinforcement, the connection according to the overlay method is used. Although there are times when this technique is allowed, it is desirable to avoid unnecessary bonding points.
Features of the calculation of fiberglass reinforcement
The advantages of the composite analogue of metal rods determined its popularity. With regard to diameter and mass, the calculation of fiberglass reinforcement for the foundation is somewhat different. Firstly, the innovative material is many times lighter than steel - for example, the weight of a 100-meter fiberglass reinforcing wrap is 8 kg. Secondly, the composite improves the strength properties of concrete, which makes it possible to reduce the thickness of the reinforcement elements. For example, if metal rods with a diameter of 1 cm are declared in the project, then you can limit yourself to 0.8 cm in diameter.
