As one of the important stages of the construction of the stairs, reinforcement is used. This process is able to give the structure maximum strength due to the stabilization of concrete.
Concrete staircase reinforcement rules
A monolithic staircase during operation is subjected to various influences and loads. A similar structure is constantly under the influence of its weight and the mass of people who use it. This causes stretching of the lower layers of the material and compression of the upper.
Such deformations lead to destruction over time. In order to exclude such consequences, reinforcement of structures is used. Such work should be carried out in three stages, namely:
- formwork installation;
- installation of reinforcing cage;
- pouring concrete mortar.
Preparation of materials and tools
The most difficult is the first stage. Creating a formwork requires accuracy and attentiveness on the part of the master. Reinforcing a monolithic staircase is a rather complicated process, without it it will not be possible to achieve technical rigidity. For reinforcement, a standard set of building materials and tools is used. To carry out the manipulations, it is necessary to prepare:
- plastic clips
- fittings of suitable section;
- reinforcing clamps;
- nippers;
- knitting wire;
- 4 mm mesh.
The latter will be needed for the arrangement of steps. Among other things, it is necessary to prepare a reinforcement plan, you will need an electric screwdriver, a welding machine. It is important to determine the distance between the elements of the reinforcement, because metal rods should be laid according to the plan.
Formwork installation
Reinforcement of stairs involves the installation of formwork, for this, boards or plywood sheets are used. 5 mm canvases can be used. Thick wooden blocks are suitable for supports. Formwork must be protected from moisture by polyethylene or roofing material.
Separate elements must be fixed with universal screws or screws. In this case, the design after can be quite easily disassembled. The rods are connected together in one of two ways, it can be a knitting wire or spot welding. Home masters most often use knitting according to a manual technique. However, it is justified only in cases where the amount of work is relatively small. In other cases, welding equipment is used, this allows to reduce labor and material costs.
Annealed steel wire products with a diameter of 1 mm should be prepared for knitting. They are pre-cut into pieces whose length is 0.3 m, after which bundles are collected. This can be done with springs or plastic clamps.
Reinforcement frame preparation
You can connect wire nodes using one of several methods, among them:
- double row;
- angular;
- cross
- meter knot.
In order to simplify the knitting, because it is quite laborious, you should install a hook on the screwdriver, which can be purchased at a hardware store. If you don’t want to spend extra money, you can carry out such work with the help of wire cutters. Reinforcement of stairs should involve the linking of two rods, for this they are overlapped, the length of which must be calculated by multiplying the cross section of the reinforcement by 50. Then the elements are connected to each other in three places by steel wire.
Profile Selection and Frame Installation
Reinforcement of the staircase involves the use of a skeleton of A-400 or A-500 rods, the cross-section may be equal to the limit of 1 to 4 cm. Recently, Euro fittings are most often used. It is characterized by the presence of transverse ribs on both sides, with repeated loads it is able to increase the endurance of the reinforcement.
A profile with ribs is notable for a small amount of adhesion to the solution, so it is better to prefer four-sided euro rods, whose strength is 500 MPa. When deformed, the rods have high adhesion to the concrete mixture.
Reinforcement pattern
Reinforcement of stairs is most often carried out according to the technology, when the reinforcing mesh is installed bottom and top. The frame is prepared from individual elements by bonding or welding. If you use clamps, this allows you to install mesh products at a certain distance.
When it comes to monolithic staircases, most often they have a thickness of not more than 20 cm. For them, the latches should be selected so that their height does not exceed 10 cm. The upper and lower grids should be connected by hooks. Installation is made on the longitudinal rods, and they need to be staggered. The reinforced staircase reinforcement scheme also provides for the use of plastic bosses. They are located between the formwork and the reinforcement.
The use of such elements ensures uniform installation of the frame in the monolith of the staircase. From the lower to the upper edge of the structure, the frame is installed at a distance of 3 cm. Reinforcement should begin from the bottom, this is due to the fact that the loads on the structure are directed from above.
Reinforcement scheme selection
Reinforcement of concrete stairs should be done with the help of bar reinforcement, if we are talking about a simple shape design. When preparing a reinforcing cage, some home craftsmen lay it in the formwork in the form of steel channels located on the sides. Sometimes for this, beams are also used, as well as corners. It will not be worse from this, but such expenses of material and forces can be considered useless.
Reinforcement at the bottom is enough to absorb tensile forces. If you have to work with a monolithic single-march staircase, which does not have run-down steps of a monolithic platform, then the frame will need to be located only at the bottom of the plate, where tensile forces are concentrated. Sometimes the upper part of the stairs is reinforced with steel mesh with dimensions of 100 x 100 x 5 mm. This approach does not increase stiffness, but only protects the steps with strong impacts.
Such a simple nature of the impact on the single-flight ladder makes it possible to reinforce the structure using a simplified technique when drawing up a scheme. The distance between the transverse reinforcement is usually 40 cm. As it should be used 10 mm rods. Reinforcement of the steps of the ladder involves determining the height of the working plate, the diameter of the longitudinal reinforcement and the pitch between the rods. It is necessary to select these parameters, given the free span of the flight of stairs.
Thus, if the span is 2 m, then the minimum height of the staircase slab will be 10 cm, and the maximum distance between the rods will be 19 cm, and the diameter of the reinforcement should be 10 mm. The last parameter increases to 12 mm if the minimum height of the staircase slab is 20 cm, and the maximum distance between the rods is equivalent to 15 cm. In this case, the span of the staircase will be 4 m.
Main reinforcement units
You can independently carry out the reinforcement of the stairs. The nodes, which will be described below, must be arranged in accordance with the rules. For example, monolithic platforms need to be reinforced not only from below, but also from above, while the upper reinforcement partially continues in the staircase. The upper reinforcement cage must be matched similarly to the lower reinforcement.
The platforms of the two marching stairs will undergo great efforts, so they should be fixed to the wall. To do this, one of the nodes is used - a reinforced concrete crown, which deepens into the wall, its size should be 20x20 cm. To fix the monolithic site, walls of concrete blocks, concrete or brick will be needed. In the latter case, free recesses are made in the material, while when erecting walls of monolithic concrete, wooden trapezoid or foam products are laid in the formwork, which also represent the reinforcement units. To increase the structural rigidity of the stairs, monolithic platforms should be fixed in the reinforcing cage of the lower and upper reinforcement.
Rebar calculation
A staircase, reinforcement, the calculation of which you can carry out yourself, can be erected by you without outside help. You can determine the number of bars of longitudinal reinforcement by determining the length of the stairs, which must be divided into the step of the crate. Further, this value is multiplied by the length of the longitudinal rods. The same technology is applied in the case of cross-links, then these values are added and multiplied by 2, because the reinforcing cage involves the installation of rods in two rows.