Compensation method for bridge vertical prestress loss based on surface embedding prestress slats

Abstract

The invention discloses a method for compensating the vertical prestress loss of bridges based on embedding prestressed slats on the surface. The steps are as follows: step S1: cutting out prefabricated grooves on the concrete protective layer of the web of the bridge structure; step S2: installing the plates The strip clamp and the tensioning device are fixed to the protective layer of the web at the fixed end and the tensioning end respectively, and the tensioning end strip clamp and the sensor are installed; Step S3: Anchoring and Stretching the slats; step S4: filling the prefabricated groove with adhesive; step S5: completing the stretching; after the adhesive reaches the curing strength, release the prestress applied by the tensioning device, so that the tensioning end and the fixed end clamp occur Sliding, the prestress on the slats is released. The invention has the advantages of good durability, good construction convenience, and can increase web cracking load and shear bearing capacity.

Description

technical field

[0001] The invention mainly relates to the technical field of bridge reinforcement, in particular to a method for compensating vertical prestress loss of bridges based on embedding prestress slats on the surface. Background technique

[0002] In the prior art, prestressed concrete box girders generally apply preload to the web by setting vertical prestressed steel bars to offset part of the main tensile stress caused by self-weight and external loads, so as to curb the occurrence of oblique cracking of the web . However, due to the limited height of the box girder, the length of the vertical prestressed tendons is relatively short. When the tensile control stress is reached, the elongation of the high-strength finish-rolled thick steel bar is limited. If there is a slight carelessness in anchoring, the steel bar will shrink. Too much vertical prestress is lost due to the large amount, and the shrinkage and creep of concrete often leads to serious prestress l...

Examples

Embodiment Construction

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0041] Such as figure 1 As shown, the bridge vertical prestress loss compensation method based on surface embedded prestressed slats of the present invention is applied to prestressed concrete box girders as an example, and its steps are:

[0042] Step S1: Grooving;

[0043] Use a slotting machine to cut a prefabricated slot 3 of the designed size on the concrete cover of the web 2 (such as a box girder web).

[0044] The slotting angle is the angle at which the slats 4 (such as FRP slats) are embedded, and can be designed as vertical or oblique 45° or other required angles (such as figure 2 , 3 ).

[0045] The depth, width, range and spacing of slots should be designed according to the amount of reinforcement to achieve the purpose of closing oblique cracks or compensating for the lost vertical prestress, and to ensure that the ...

technical field

[0001] The invention mainly relates to the technical field of bridge reinforcement, in particular to a method for compensating vertical prestress loss of bridges based on embedding prestress slats on the surface. Background technique

[0002] In the prior art, prestressed concrete box girders generally apply preload to the web by setting vertical prestressed steel bars to offset part of the main tensile stress caused by self-weight and external loads, so as to curb the occurrence of oblique cracking of the web . However, due to the limited height of the box girder, the length of the vertical prestressed tendons is relatively short. When the tensile control stress is reached, the elongation of the high-strength finish-rolled thick steel bar is limited. If there is a slight carelessness in anchoring, the steel bar will shrink. Too much vertical prestress is lost due to the large amount, and the shrinkage and creep of concrete often leads to serious prestress l...

Examples

Embodiment Construction

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0041] Such as figure 1 As shown, the bridge vertical prestress loss compensation method based on surface embedded prestressed slats of the present invention is applied to prestressed concrete box girders as an example, and its steps are:

[0042] Step S1: Grooving;

[0043] Use a slotting machine to cut a prefabricated slot 3 of the designed size on the concrete cover of the web 2 (such as a box girder web).

[0044] The slotting angle is the angle at which the slats 4 (such as FRP slats) are embedded, and can be designed as vertical or oblique 45° or other required angles (such as figure 2 , 3 ).

[0045] The depth, width, range and spacing of slots should be designed according to the amount of reinforcement to achieve the purpose of closing oblique cracks or compensating for the lost vertical prestress, and to ensure that the ...

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