Greetings, dear professionals and amateur self-builders!
Today, every forum discusses a bunch of problems on the reinforcement of various structures in buildings and other building structures, and it is incredible you can often see and hear from, to put it mildly, incompetent people that reinforcement in reinforced concrete works only in tension, and concrete itself only works in tension. compression!
Whatever reinforced concrete structure is given to them as an example, the answer will be the same.
"Is it true that concrete does not work in tension, but only in compression?", I once asked this question to the guys who are calculating the bridges. "This is nonsense, where did you hear that?"- the engineer answered me. This was one of the main questions after our acquaintance. And to this day, sometimes, in dialogues with rather experienced builders building high-rise buildings, I hear a refutation of these statements. And this is true, since the reinforcement works in tension, and concrete works in compression - this is a blatant injection of information that misinforms people.
If we imagine two completely opposite actions "stretch" and "squeeze", then even logically we can conclude that any material can resist these two actions.
And in fact, having lifted the codes of practice and materiel on the strength of materials, we will see that any building material works both in compression and in tension.
But where did this myth come from?
The fact is that builders (engineers) know that in some cases it is possible to simplify calculations, therefore in them for the sake of optimization and minimization of computations - the resistance of some materials neglected. In view of this, such a myth arose among inexperienced people.
The basic set of rules for reinforced concrete structures shows that both reinforcement and concrete work both in tension and compression. Don't believe me? See for yourself, as an example I cite a table of the design resistance of concrete, where there are its characteristics of resistance to both compression and tension:
As for the reinforcement, I think no one will doubt that it perfectly resists compression, try to flatten it - the concrete will fly faster than the bar will collapse. True, this only applies to steel, for composite reinforcement this indicator is very small and is not taken into account.
The tensile strength of concrete can be ignored, for example, when a reinforced concrete structure takes the form of a beam and we consider it to bend. This parameter is much lower than the tensile strength of the reinforcing steel bar and is easier to neglect than to complicate the task.
But, the tensile strength of concrete is very much taken into account in other calculations, for example, it is involved in the calculations of inclined sections and this parameter is very important there!
The reinforcement works both in tension and compression in all places where it is laid!
Summing up, I will repeat once again that both materials work in two directions, and the difference is only in the values of resistance to certain loads applied to them! If the resistance of any material is extremely low in relation to another material, then it sometimes does not participate in the calculations and everything depends solely on the calculated structure!