Предварительно напряженный бетон 12 7 мм опорный Натяжной цилиндр и клиновидный

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Трекер стоимости

Характеристики

12.7mm Prestressed Concrete and Post-tensioning barrel and Wedges factory

The main systems of prestressing are pretensioning and posttensioning.

In the case of pretensioning, the prestressing tendons are tensioned before the casting of concrete. The prestress will be released from the temporary anchorages and transferred to the element after the concrete hardens. The transmission of the prestressing force to the structural element is generally ensured by bonding over the interface of prestressing tendons and concrete. The common types of prestressing steels are eccentrically placed straight strands with nominal diameters of 13 or 15 mm. This technology is mainly used to produce precast bridge girder beam elements in precast plants.

 

Posttensioning is the commonly used technology in long-span cast-in-situ r.c. bridge constructions. In this case, the prestressing tendons are tensioned after the concrete hardens. Special-end anchorages are fixed to the concrete, which transfer the prestressing forces to the structural element. Prestressing can be provided by prestressing wires, strands, cables, or bars. Cables usually consist of 3 to 55 strands as a function of the prestressing force. The layout of tendons for posttensioning can be selected so as to have the optimal effect of prestressing.

 

The tendon must be freely movable in the element to be tensioned after hardening the concrete. To achieve this, the tendons are enclosed in metal or plastic ducts. The ducts are generally filled by cement grout to improve corrosion protection and provide bonding between tendons and the surrounding concrete.