Evaluation of extreme anchors
Introduction
The general term is Prestressed Concrete which includes Prestressed Concrete and Post-tensioned Concrete.
Post-tensioned concrete or post-tensioned concrete is called concrete/concrete that is subjected, after pouring and setting, to compression forces by means of active reinforcement (steel cables) mounted inside sheaths. Unlike pre-tensioned concrete, in which the reinforcement is tensioned before concreting, in post-tensioning the reinforcement is tensioned once the concrete has acquired its characteristic strength.
In this way, prestressing can be achieved in two ways: prestressing (with pre-tensioned reinforcement) and post-tensioning (with post-tensioning reinforcement). The general word "prestressed" is used to simultaneously refer to both prestressed concrete and post-tensioned concrete, where what changes is the moment at which the tensioning of the cables occurs.
As in pre-tensioned concrete, the advantage of post-tensioning is to compress the concrete before it is put into service, so that the traction that appears when the piece is bent translates into a loss of the previous compression, preventing to a greater or lesser extent the concrete from working in traction, an effort for which it is not a suitable material.
System Description
Unlike ordinary reinforced concrete, the reinforcement is not directly in contact with the concrete at the time of concreting, since otherwise it would transmit the tensile stress due to adhesion between the reinforcement and the concrete. For this reason, the armor is placed inside plastic or metal sheaths. These pods are positioned within the formwork (the mold) forming a curved line defined in the design phase, depending on the shape of the piece and the loads to which it will be subjected.
Once the working tension has been applied to the reinforcements, they are anchored to the structure using special pieces at both ends. Finally, there are two options:
• - In the "adherent" system, the interior of the pods is filled with high pressure resistance mortar, so that the reinforcement remains adhered to the concrete, forming a monolithic section. In turn, the mortar ensures the protection of the steel against corrosion.