During the construction of foundations, it is not uncommon to resort to reinforcing processes that can improve the strength characteristics of foundations and thereby significantly extend the service life. Consider several options and the reasons why it is necessary to reinforce the strip foundation.
In the first case, if our strip foundation has dimensions at which its height is greater than the height of the base, then it is necessary to carry out its transverse reinforcement. To do this, reinforce the foundation cushions, for which a lower mesh is installed. This allows avoiding such a negative phenomenon as the occurrence of a bending moment with such a foundation geometry, at which the lower part of the foundation can stretch. And given the fact that concrete does not tolerate such tensile forces, therefore, there is a need for reinforcement.
In addition to the above-mentioned transverse, there is also longitudinal reinforcement of the strip foundation. Such a process of reinforcement is caused by uneven soil density, uneven loading on different parts of the foundation, the possibility of subsidence of the foundation and unevenness of this process, as well as the possibility of bending in the longitudinal plane. And in order for the foundation not to collapse, it is necessary to reinforce it. For these purposes, apply the upper and lower mesh. In this case, it is best to use grids made of reinforcement with a cross section of 12 mm.
Consider now the rules applied in the reinforcement process. Firstly, the reinforcement of the strip foundation is carried out in strict accordance with the rules for reinforcing concrete products and structures. In addition, the upper protective layer covering the upper mesh must be at least the size of the diameter of the reinforcement used in the mesh for work. And when reinforcing the foundation with a lower mesh, the protective layer should be equal to 70 mm. Basically, for reinforcing foundations, a mesh with a cell side of 200 mm is used. Moreover, the mesh design can be either welded or knitted.
Cross reinforcement of the strip foundation requires preliminary calculations. Take, for example, the condition that we will reinforce the foundation with reinforcement with a diameter of 12 mm and a cell side of 200 mm (mesh pitch). As mentioned earlier, the transverse reinforcement of the strip foundation depends on the moment of bending in the pillow (base) of the foundation. The bending moment itself can be calculated by the following formula: Q xbxb / 2, where the value of Q - is the pressure value exerted on the foundation cushion. The appropriate diameter of the reinforcement for reinforcement is calculated by calculating the cushion plate for the effect of the directly bending moment. As a rule, for these purposes, a grid pitch of 200 mm is taken.
In addition, the foundation pillow can be additionally calculated for the possibility of breaking through the wall (such deformations depend on the size of the brickwork you plan to use in the walls). If there is a likelihood of strong such punching, then the punching prism can be further enhanced by vertical grids for reinforcement.
It is also necessary not to forget about taking into account the deflections of the foundation edge relative to the central part. Such deformation can create uneven pressure of the foundation on the ground. And if the base cushion is wide, this can lead to a decrease in the effectiveness of the entire strip foundation as a whole.
If during the calculation process it is proved that even the use of reinforcement of the largest profile is not enough for reinforcement, then the dimensions of the foundation are revised, in the direction of thickening the pillow. However, it is worth remembering that with this approach, concrete consumption for the construction of a strip foundation can significantly increase.
In addition to foundations, brickwork reinforcement is also often performed . This allows the wall of the house, even in the case of uneven loads on the foundation, to distribute them more efficiently and evenly and protect the entire building structure from deformation and subsequent destruction.