Which of the following post tensioning system adopts metallic sandwich plates, flat wedges and distribution plate for anchoring the wires?

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answered Feb 27, 2022 by Pravask (114k points)
selected Feb 27, 2022 by tushark

Best answer

Correct Answer - Option 1 : Magnel-Balton

Concept:

Various post-tensioning systems are discussed below:

Magnel-Balton system:

This method was introduced by a famous engineer, Prof. Magnel.
In Magnel Blaton system, two wires are stretched at a time.
In this system, the anchorage device consists of a sandwich plate having grooves to hold the wires and wedges which are also grooved. Each plate carries eight wires.
Between the two ends, the spacing of the wires is maintained by spacers. Wires of 5 mm or 7 mm are adopted. Cables consist of wires in multiples of 8 wires. Cables with as many as 64 wires are also used under special conditions.

Lee-McCall system:

This method is used to prestress steel bars. The diameter of the bar is between 12 and 28 mm.
Bars provided with threads at the ends are inserted in the performed ducts. After stretching the bars to the required length, they are tightened using nuts against bearing plates provided at the end sections of the member.

Gifford-Udall system:

This is a single-wire system. Each wire is stressed independently using a double-acting jack. Any number of wires can be grouped together to form a cable in this system.
There are two types of the anchorage device in this system:
- Tube anchorages
- Plate anchorages

Freyssinet system:

The Freyssinet system was introduced by the French Engineer Freyssinet and it was the first method to be introduced.
High strength steel wires of 5 mm or 7 mm diameter, numbering 8 or 12 or 16 or 24 are grouped into a cable with a helical spring inside. Spring keeps proper spacing for the wire. The cable is inserted into the duct.
Anchorage device consists of a concrete cylinder with a concentric conical hole and corrugations on its surface, and a conical plug carrying grooves on its surface.
Members are fabricated with the cylinder placed in position. Wires are pulled by Freyssinet double-acting jacks which can pull through suitable grooves all the wires in the cable at a time.