Slow-bonded low-retraction prestressed short cable system, calculation thereof and tensioning method thereof

Abstract

The invention provides a slow-bonded low-retraction prestressed short cable system. The slow-bonded low-retraction prestressed short cable system includes a clip-type anchorage device, an anchor cup,a support nut, a first backing plate and a slow-bonded prestressed tendon, wherein a clip of the clip-type anchorage device at the tension end is used to combine the slow-bonded prestressed tendon with the anchor cup together, and then the tensioned pre-stress is transmitted to the first backing plate by threaded engagement between the support nut and the anchor cup. The invention also provides adesign calculation method and a tensioning method of the slow-bonded low-retraction prestressed short cable system, capable of reducing the anchoring retraction loss and solving the problem of the grouting quality.

Description

technical field [0001] The invention relates to the technical field of civil engineering design and construction, in particular to the lateral and vertical prestressing of prestressed concrete bridges. Background technique [0002] The web cracks of prestressed concrete bridges are concentrated between 25° and 45°, which are structural main tensile stress cracks, which mainly appear in the cast-in-place section of the side hole of the continuous box girder bridge, near the L / 4 section or the thickness of the beam web change section. The oblique cracks in the web develop continuously from the vicinity of the support to the compression zone with the passage of time, the number of cracks continues to increase, and the crack area gradually expands to the mid-span direction. Judging from the overall distribution characteristics of cracks, such cracks are mostly in the direction perpendicular to the main tensile stress in the web, which can basically be determined as the cracking...

AI Technical Summary

Problems solved by technology

[0010] (2) Insufficient quality of vertical grouting

Using movable struts and pouring mortar in the casing may cause strength problems caused by the retraction caused by the pitch of the rebar

However, in the tensioning method, movable struts, sleeves, and reinforcing rings are set, which makes the construction difficult and the process complicated

[0020] Chinese patent CN103726447A discloses a method and system for vertically prestressed steel strands in a secondary tension low-retraction anchorage system, which only relies on secondary tension to solve the problem of low retraction, but does not solve the problem of insufficient grouting quality, steel bars Bonding with concrete slurry causes problems such as stress concentration; in addition, the parameters in the tensioning method are determined by experience, and the range value is too large to make accurate adjustments according to the actual situation

[0021] Chinese patent CN205531024U discloses a prestressed anchorage system for low-retraction fine-rolled threaded steel bars, using threaded steel bars and secondary tensioning technology, the problems of retraction and tensioning accuracy caused by the pitch cannot be solved

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