Reinforcement of ladders: calculation and scheme
Reinforcement is one of the important stages in the construction of the staircase. This process is able to give the design maximum strength due to the stabilization of concrete.
Rules for reinforcing a concrete staircase
Staircase monolithic construction in processoperation is subjected to different impacts and loads. Such a structure is constantly still under the influence of its weight and the mass of people who use it. This causes the stretching of the lower layers of the material and the squeezing of the upper layers.
Similar deformations with time lead to destruction. In order to exclude such consequences, reinforcement of structures is used. Such work should be conducted in three stages, namely:
- installation of formwork;
- installation of reinforcing cage;
- pouring of concrete.
Preparation of materials and tools
The most difficult is the first stage. Creation of the formwork requires accuracy and attention on the part of the master. Reinforcement of the monolithic ladder is a rather complicated process, without it you will not be able to achieve technical rigidity. For reinforcement, a standard set of building materials and tools is used. For carrying out manipulations it is necessary to prepare:
- plastic clips;
- reinforcement of a suitable section;
- clamps rebar;
- knitting wire;
- 4-mm grid.
The latter will be needed to arrange the steps. Among other things, you need to prepare a reinforcement plan, you need an electric screwdriver, a welding machine. It is important to determine the distance between the elements of the reinforcement, because the metal rods must be laid according to the compiled plan.
Installation of formwork
Reinforcement of stairs involves installationformwork, for this purpose boards or plywood sheets are used. You can apply a 5-mm cloth. For the poles thick wooden blocks are suitable. Formwork must be protected from moisture by polyethylene or roofing material.
Individual elements must be fixeduniversal screws or screws. In this case, the construction after it can be fairly easy to disassemble. Connect the rods together in one of two ways, this can be a knitting wire or spot welding. Home masters most often use knitting by manual technique. However, it is justified only in cases when the volume of work is relatively small. In other cases, welding equipment is used, this reduces labor and material costs.
For knitting you should prepare annealed steelwire products, the diameter of which is 1 mm. They are preliminarily cut into pieces, the length of which is 0.3 m, after which bundles are collected. You can do it with springs or plastic clips.
Preparation of the reinforcing cage
Link wire nodes can be one of several techniques, among them:
- double row;
- meter node.
In order to simplify the binding, because it isenough labor-consuming, you should install a hook on the screwdriver, which can be purchased at the building store. If you do not want to spend extra money, you can do such work with a pliers. Reinforcement of the stairs should involve the binding of two bars, for this they are overlapped, the length of which must be calculated by the method of producing a section of the reinforcement by 50. Then the elements are joined together in three places by steel wire.
Selecting a profile and installing a frame
Reinforcement of the stairs providesthe use of a skeleton from A-400 or A-500 rods, the cross-section may be equal to the limit of 1 to 4 cm. Recently, the euro fittings have been used most often. It is distinguished by the presence of transverse ribs on both sides, with multiple loads it is able to increase the endurance of the armature.
Profile with ribs differs insignificantlythe value of adhesion to the solution, so it is better to prefer four-sided europrints, the strength of which is 500 MPa. When deformed, the rods have high adhesion to the concrete mix.
The reinforcement of stairs is most oftentechnology, when the reinforcement mesh is installed from below and from above. The frame is prepared from individual elements by the method of binding or welding. If you use fixatives, then it allows you to install grid products at a certain distance.
When it comes to monolithic staircasesstructures, they most often have a thickness of not more than 20 cm. For them, the locks should be selected in such a way that their height does not exceed 10 cm. The upper and lower meshes must be connected together by hooks. Installation is made on longitudinal rods, and they need to be staggered. Scheme reinforcement monolithic stairs also provides for the use of bosses made of plastic. They are placed between the formwork and the armature.
Use of such elements providesuniform installation of the frame in the ladder monolith. From the bottom to the top edge of the structure, the frame is set 3 cm apart. Reinforcement should begin from the bottom, this is because the load on the structure is directed from above.
Choice of reinforcement scheme
Reinforcement of the concrete staircase mustIt is produced with the help of rod reinforcement, when it comes to the design of a simple mold. Some home masters in the preparation of the reinforcing cage lay it in a formwork in the form of steel channels, located at the sides. Sometimes for this purpose also beams are used, and also corners. Worse, this will not happen, but such material and force costs can be considered useless.
The reinforcement at the bottom is sufficient forperception of tensile forces. If it is necessary to work with a monolithic single-ladder ladder that does not have the steps of the monolithic landing stage, then the skeleton will need to be located only in the lower part of the plate, where the tensile forces are concentrated. Sometimes the upper part of the ladder is reinforced with a steel mesh with dimensions of 100 x 100 x 5 mm. This approach does not increase the rigidity, but only protects the steps with strong shocks.
Such a simple nature of the impact ona single-ladder ladder allows you to reinforce the structure in a simplified procedure. The distance between the transverse reinforcement is usually 40 cm. 10 mm rods should be used as it. 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 bars. It is necessary to select these parameters, taking into account the free flight of the ladder march.
Thus, if the span is 2 m,then the minimum height of the stove plate will be 10 cm, and the maximum distance between the bars will be 19 cm, and the diameter of the reinforcement should be 10 mm. The last parameter is increased to 12 mm if the minimum height of the stove working plate is 20 cm and the maximum distance between the rods is equivalent to 15 cm. The length of the flight of the ladder is 4 m.
Basic reinforcement units
You yourself can be implementedreinforcement of the stairs. The nodes, which will be described below, must be arranged taking into account the rules. For example, monolithic sites need to be reinforced not only from below, but also from above, while the upper reinforcement is partially continued in the staircase. The upper reinforcement cage should be chosen similarly to the lower reinforcement.
The platforms of two marching stairs will undergogreat effort, so they should be fixed in 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 a monolithic site, walls of concrete blocks, concrete or bricks will be needed. In the latter case, free grooves are made in the material, whereas when building walls from monolithic concrete, wooden trapezium or foam products are laid in the formwork, which also represent reinforcement nodes. To increase the structural stiffness of the ladder, the monolithic platforms must be fixed in the reinforcement frame of the lower, as well as the upper armature.
Ladder, reinforcement, calculation of which you canindependently, can be built by you without outside help. Determine the number of bars of longitudinal reinforcement can be a method of determining the length of the ladder, which must be divided into a 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 assumes the installation of rods in two rows.