Prestressing Systems and Anchorage Design

In the case of pretensioned concrete structures, the tensioning of the tendon is carried out before concreting. The prestressing force is held temporarily either by a specially constructed prestressing bed or by a mould or form. When the concrete strength reaches the specified transfer strength, detensioning and stress transfer to such structures can be performed. In practice these structures are prefabricated. 

Class 2 flexural tensile stresses but no visible cracking. 

Class 3 flexural tensile stresses but surface width of cracks not exceeding 0.1 mm for members in very severe environments and not exceeding 0.2 mm for all other members. 

The structural detailing of prestressed concrete members must take into consideration durability, fire resistance and stability. The relevant codes EC2 

Generally, high-strength concrete is used for prestressed concrete work. The steel used in prestressed concrete is generally of a much higher strength than mild steel. This aspect is discussed later on in the choice and evaluation of prestressing systems. 

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