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The construction of a reinforcing cage is not to say that it is a very complex, but rather painstaking and laborious process. During the construction of the frame, there are a number of technological points that are important not to miss, and today we will talk about cross and corner reinforcement of the tape of a monolithic foundation.
Why are these elements the main focus?
Because it is in these nodes that the multidirectional forces of compression and tension are concentrated.
Leaving the corners without reinforcement, under the action of the sum of the acting forces, sliding of the reinforcement inside the concrete can be observed for due to insufficient connection of two ribbons at the corners, as a result - we get angular transverse cracks in the form of separation of the thickness concrete.
Separately taken reinforcement rods no longer work as a single system, and this is the main reason for the deformation of the structure.
According to the building rules (SP 50-101-2004) - monolithic strip foundations for all load-bearing walls of the structure must be combined into one rigid system of cross belts.
Rigid connection is provided by:
- anchoring reinforcing bars: bending in the form of a loop, hook or flattening of the end of the bar.
- bypass (overlap) value equal to> 50 bar diameters.
How to properly mate the frames of two tapes?
So, the corner of the foundation is two converging beams, on which forces act differently. One beam can undergo tension, the other - compression, therefore, the angle is the zone of concentration of multidirectional stresses.
Reinforcement depends on the type of crosshair. It can be both L-shaped and T-shaped, as well as have different angles: straight, obtuse, sharp.
Reinforcement elements are located in each row of the main rods.
Corner reinforcement (L-shaped crosshair)
Corner reinforcement with P-elements and G-elements
In the case of reinforcement with G-elements, a separate element can be omitted if it is possible to bend the main reinforcement bar at a right angle and bring it onto an adjacent wall. In this case, the longitudinal inner bar of the first wall is bent and the remaining part is joined to the outer bar of the second wall by an overlap size of not less than 50d of the bar.
It is important to reinforce the corners with diagonal elements not allowed. This technology cannot be applied when reinforcing corners with longitudinal bars, but additionally implies the use of a mesh with a cell of 200 mm * 200 mm. This is fully described in the book by Professor V.S. Sazhina “Don't bury the foundations deep” 2003
When reinforcing obtuse angles more than 160 °, reinforcement with G and P elements is not necessary.
Cross reinforcement (T-bar)
As with corner reinforcement, the overlap for each bend of the reinforcement should be at least 50 bar diameters.
T-cross reinforcement:
1) Legs and one U-shaped clamp;
2) Bend and overlap of the working reinforcement at 50d:
3) Reinforcement using G-elements:
It is important to pay enough attention to the reinforcement of the foundation and thoroughly double-check everything after the builders, since the foundation is the foundation of the house.
Its corners are subjected to much greater loads, in contrast to the longitudinal part and the usual intersection of the rods, which by itself it turns out in the corners when reinforcing the walls - it does not provide the proper rigidity of the structure and the bundles of walls between yourself.
I hope this article was useful to you!
Thanks for attention!
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