Tensioning Technology of Low Retraction Anchorage

Prestress
  1. Home
  2. /
  3. Industry News
  4. /
  5. Tensioning Technology of Low Retraction...

Low-retraction anchorage is a kind of low-retraction and high-efficiency anchor specially developed for the short prestressed beam anchor, which has a large effective permanent prestress loss due to excessive tensioning and tensioning. It can be widely used in vertical prestressed structures of bridges such as large-span prestressed concrete continuous beams and continuous steel structures, transverse prestressed structures of railway beams, circumferential and transverse prestressed structures of cable-stayed bridge towers, slope anchor prestressed structures, and other various shorter prestressed tendon structures.

Low-retraction anchorage is abbreviated as DHM15-N, that is, N is 1~4 holes.

Compared with ordinary anchorages, structurally speaking, low-retraction anchorages have an additional nut device between the anchor head and the bearing plate to reduce the retraction amount, and a pressure plate (with bolts) is added to the extrusion anchor at the dead end.

Prestress
drawing of low retraction anchorage

In terms of use, the application of low-retraction anchorages is limited to a certain extent. It is suitable for short prestressed beams and straight prestressed beams.

The tensioning of low-retraction anchorages adopts a two-stage tensioning process. The following is the process method of tensioning using an ordinary multi-strand center hole jack.

First tensioning:

First tensioning is without pressure nuts, and its tensioning method is different from the common anchorage.

Second tensioning:

1. After the first tensioning, remove the tool anchorage, stressing jack, and limit plate, and screw the anchor nut into the working anchor head.

2. Install the stressing jack and tool anchorage.

3. Supply oil to the jack for tensioning, and the steel strand drives the working anchor head and nut to move together.

4. When tensioning to the designed prestressing value, tighten the anchor nut from the side with a special wrench, return oil to the jack, release tension and anchor.

5. Remove the tool anchorage and jack, and cut off the excess steel strand.

6. Grout and seal the anchor.

Share this post

Explore More...