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Method and system for vertically prestressed steel strands in secondary tension low-retraction anchorage system

A vertical prestressing, steel strand technology, applied in the erection/assembly of bridges, bridge materials, bridges, etc., can solve the problems of large prestress loss, reduced service life of the main bridge box girder, low stress level, etc. The effect of large prestress loss, extended operation period and engineering quality assurance

Active Publication Date: 2016-12-07
CCCC SHEC FOURTH ENG +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The traditional vertical prestressed finish-rolled thread anchorage system has problems such as low stress level, small elongation, large prestress loss, and easy tendon breakage during construction, which greatly reduces the service life of the main bridge box girder and the design service life of the bridge. There are limitations

Method used

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  • Method and system for vertically prestressed steel strands in secondary tension low-retraction anchorage system
  • Method and system for vertically prestressed steel strands in secondary tension low-retraction anchorage system
  • Method and system for vertically prestressed steel strands in secondary tension low-retraction anchorage system

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Embodiment Construction

[0021] The following non-limiting examples illustrate the invention.

[0022] Such as Figures 1 to 3 As shown, a method for vertically prestressed steel strands in a secondary tension low-retraction anchorage system, in which the anchor cup 3 is externally threaded with a support nut 4, and the tension end pad 6 is placed below, and the support nut 4 supports the anchor cup 3. On the backing plate 6 at the tension end, the following steps are successively included:

[0023] One-time tensioning: single tension steel strand reinforcement 1 to the designed stress value σcom, holding load 120±30s, release tension, low retraction clip 2 anchor reinforcement reinforcement, three steel strand reinforcement reinforcement 1 in the same group The stretching is completed in sequence;

[0024] Secondary tensioning: After the primary tensioning low retraction clip 2 is anchored and retracted, at an interval of 2-16 hours, the anchor cup 3 of the steel strand reinforcement 1 of the same ...

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Abstract

The invention discloses a method and a system for secondary tensioning of low-retraction anchorage system vertical prestressed steel strands and belongs to a method and a system for prestressed construction of structural box beams on the upper portion of a bridge. The method includes: sequentially tensioning an individual steel strand force rib to the designed stress value of sigma com and with sustained stocks of 120+ / -30s, releasing and using clamping pieces to anchor the force ribs; after retraction of the primary tensioning and clamping piece anchoring, integrally tensioning anchor cups of the same-group steel strand force ribs to sigma com once every 2 to 16 hours till the anchor cups ascend by 3-10 mm in height with the sustained stocks of 120+ / -30s, fixing the height of the anchor cups and releasing. The secondary tensioning system is characterized in that a connecting sleeve is in threaded connection with the anchor cups and a pull rod, a pull rod nut is connected with the pull rod and a jack, the jack connects and pulls up the pull rod, and a tensioning support connects and supports the jack. By the arrangement, prestressed level can be improved, prestressed losses can be reduced, a box beam web plate can be effectively prevented from cracking, and service life of a bridge can be prolonged.

Description

technical field [0001] The invention belongs to a method and a system for prestressed construction of a box girder of a bridge superstructure, and is suitable for the vertical prestressed construction of a large-span continuous rigid structure and a continuous girder box girder web. Background technique [0002] 1) Traditional vertical prestressed finishing thread construction technology: [0003] The prestress is the skeleton structure of the main girder of the bridge superstructure. The main function of the vertical stress of the box girder web is to prevent the longitudinal cracks of the web, increase the overall stiffness of the bridge, and prolong the service life of the bridge. During conventional construction, the prestressed finish-rolled threaded steel bars are often pre-embedded on the web of the bridge box girder, and the construction is carried out with a tensioned anchorage system. The anchorage is anchored by manually tightening the finish-rolled threaded nuts...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E01D21/00E01D101/28
Inventor 王年福汪晓燕严登山
Owner CCCC SHEC FOURTH ENG
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