Prestress FRP rib self-resetting fabricated pier structure and construction process thereof

Abstract

The invention relates to a prestressed FRP (Fiber Reinforce Plastic) rib self-resetting fabricated pier structure and a construction process thereof, and the prestressed FRP rib self-resetting fabricated pier structure comprises a bearing platform, alkali-activated recycled aggregate concrete arranged in a groove in the upper surface of the bearing platform, and a prefabricated pier body arranged in the alkali-activated recycled aggregate concrete, the bearing platform, the alkali-activated recycled aggregate concrete and the prefabricated pier body are provided with through holes which are formed in the length direction and directly face each other, prestressed FRP ribs are arranged in the through holes, the first ends of the prestressed FRP ribs are anchored in counter bores in the lower surface of the bearing platform, and the second ends of the prestressed FRP ribs are anchored in counter bores in the upper surface of the prefabricated pier body; prestress is applied to the prestress FRP ribs in advance, so that the fabricated pier can recover to the initial state after being subjected to external force, the anti-seismic and anti-fatigue performance of the fabricated pier structure can be improved, the service life of the structure can be prolonged, and meanwhile energy conservation, emission reduction and sustainable development are achieved.

Description

Technical Field: The present invention relates to a prestressed structure technology for a new type of assembled pier, in particular to a prestressed FRP bar self - resetting assembled pier structure and its construction technology. Background Art: At present, after the assembled pier structure is subjected to a large external force impact, it is prone to tilt, and after tilting, it is prone to cause the risk of building collapse.

[0003] For example, in the Chinese patent "A multi - column assembled pier structure system with non - destructive control", publication number CN218596898U, which includes a capping beam, pier column, pile cap, and pile foundation arranged in sequence from top to bottom. A groove is provided on the upper surface of the pile cap, and the bottom of the pier column is placed in the groove. Isolation rubber pads are filled in both the end gap and the peripheral gap between the pier column and the groove. Connecting sleeves are reserved at the inner bottom of both the capping beam and the pier column. The upper parts of several reserved longitudinal bars in the pier column are lapped with several reserved steel bars buried in the capping beam through the connecting sleeves, and the lower parts of several reserved longitudinal bars in the pier column are lapped with several reserved steel bars of the pile cap through the connecting sleeves. Although the patent connects the pile caps through a tie beam and has excellent seismic isolation effect, which can reduce the impact of live load and seismic force on the building and greatly improve the seismic capacity of the bridge; however, after being subjected to a large external force impact, it is prone to tilt and cannot automatically return after tilting, which is prone to cause the risk of building collapse.

[0004] Another example is the Chinese patent "A hierarchical energy - dissipating self - resetting assembled pier column", publication number CN114412259B, which includes a spherical part provided at the bottom end of the column body; the base is provided with an arc groove for accommodating the spherical part, and a first friction pad is provided between the arc groove and the spherical part; energy - dissipating mechanisms are respectively arranged on both sides of the column body. The energy - dissipating mechanism mainly includes a first connecting plate, a second connecting plate, a cover plate, a first fastener, a second fastener, and a second friction pad. By setting the first friction pad and the energy - dissipating mechanism, when the pier column structure encounters disasters of different types and levels, it can provide hierarchical energy dissipation according to the structural deformation state and has the characteristics of quick disassembly, installation, and repair after an earthquake, realizing high - performance assembly; although this patent can achieve self - resetting after a disaster, its structure is complex, the construction period is long, and the cost is high. Summary of the Invention: In view of the above - mentioned deficiencies of the prior art, the purpose of the present invention is to provide a prestressed FRP bar self - resetting assembled pier structure and its construction technology with simple structure and convenient and fast construction.

[0006] The prestressed FRP bar self - resetting assembled pier structure of the present invention is characterized in that: it includes a bearing platform, alkali - activated recycled aggregate concrete arranged in a groove on the upper surface of the bearing platform, and a precast pier body arranged in the alkali - activated recycled aggregate concrete. The bearing platform, alkali - activated recycled aggregate concrete, and precast pier body are provided with through - holes arranged along the length direction and facing each other. A prestressed FRP bar is arranged in the through - hole. The first end of the prestressed FRP bar is anchored in a counterbore on the lower surface of the bearing platform, and the second end of the prestressed FRP bar is anchored in a counterbore on the upper surface of the precast pier body; by pre - applying prestress to the prestressed FRP bar, the assembled pier can return to its initial state after being subjected to external forces.

[0007] Preferably, a cushion block is arranged in the groove on the upper surface of the bearing platform, and the cushion block is embedded in the alkali - activated recycled aggregate concrete.

[0008] Preferably, the material of the prestressed FRP bar is carbon fiber reinforced composite material.

[0009] Preferably, the alkali - activated recycled aggregate concrete includes construction waste recycled aggregate, sand, fly ash, slag, alkaline activator, and water.

[0010] The construction technology of the prestressed FRP bar self - resetting assembled pier structure of the present invention is characterized in that: (1) Precast a bearing platform with a groove on the upper surface, a counterbore on the lower surface, and a through - hole in the center; (2) Precast a precast pier body with a counterbore on the upper surface and a through - hole in the center; (3) Prepare alkali - activated recycled aggregate concrete; (4) Thread a FRP bar from bottom to top through the through - hole of the precast bearing platform. The first - end anchor head of the FRP bar is limited in the counterbore on the lower surface of the bearing platform, and the second end of the FRP bar extends out of the groove on the upper surface of the bearing platform; (5) Place a cushion block in the groove on the upper surface of the bearing platform and pour alkali - activated recycled aggregate concrete. Then, thread the second end of the FRP bar from the bottom to the top through its through - hole in the precast pier body, so that the second end of the FRP bar passes through the counterbore on the upper surface of the precast pier body, and vertically place the precast pier body above the cushion block in the groove; (6) Use a tensioning tool to tension the second end of the FRP bar and use a tensioning - end anchor to anchor it in the counterbore on the upper surface of the precast pier body.

[0011] By introducing FRP bars into the pier structure and applying prestress, the present invention can achieve self - reset function, thereby enhancing the seismic performance of the structure; and alkali - activated recycled aggregate concrete is set in the groove on the upper surface of the pile cap, which can effectively utilize construction waste and improve the durability and green environmental protection performance of the concrete; therefore, the present invention can improve the seismic and anti - fatigue performance of the assembled pier structure, extend the service life of the structure, and at the same time achieve energy conservation, emission reduction and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS: Figure 1 It is a schematic diagram of the connection structure of the present invention; In the figure: 1 - anchorage end; 2 - pile cap; 3 - alkali - activated recycled aggregate concrete; 4 - precast pier body; 5 - prestressed FRP bar; 6 - tension - end anchor; 7 - spacer; 8 - groove; 9 - through - hole. DETAILED DESCRIPTION OF THE INVENTION: The following further describes the present invention in conjunction with the drawings and specific embodiments.

[0014] The prestressed FRP bar self - reset assembled pier structure of the present invention includes a pile cap 2, alkali - activated recycled aggregate concrete 3 arranged in the groove 8 on the upper surface of the pile cap, and a precast pier body 4 arranged in the alkali - activated recycled aggregate concrete. Through - holes 9 are provided on the pile cap 2, alkali - activated recycled aggregate concrete 3 and precast pier body 4 and are arranged opposite to each other along the length direction. The prestressed FRP bar 5 is arranged in the through - hole. The prestressed FRP bar has self - reset ability by applying prestress. The first end of the prestressed FRP bar is anchored in the counterbore on the lower surface of the pile cap, and the second end of the prestressed FRP bar is anchored in the counterbore on the upper surface of the precast pier body; by pre - applying prestress on the prestressed FRP bar, the assembled pier can return to the initial state after being subjected to external forces.

[0015] The alkali - activated recycled aggregate concrete has excellent durability and anti - permeability performance, can improve the fire resistance and chemical corrosion resistance of the structure, and extend the service life of the structure; the alkali - activated recycled aggregate concrete 3 is filled around the prestressed FRP bar 5, which can enhance the overall performance of the structure.

[0016] Specifically, the alkali - activated recycled aggregate concrete 3 includes construction waste recycled aggregate, sand, fly ash, slag, alkaline activator and water. Using industrial solid wastes (such as mineral powder, fly ash) as cementitious materials, without calcination, avoiding high carbon emissions in traditional cement production.

[0017] By the anchor of the prestressed FRP bar 5 end and extending the depth of the prestressed FRP bar 5 embedded in the precast pier body 4 and pile cap 2, the bond between the prestressed FRP bar 5 and the precast pier body 4, pile cap 2, and alkali - activated recycled aggregate concrete 3 is enhanced, ensuring effective collaborative work among them.

[0018] By applying prestress between the prestressed FRP bars and the alkali-activated recycled aggregate concrete, the friction force at the interface between the FRP bars and the alkali-activated recycled aggregate concrete is increased, the interfacial bonding force is improved, and the overall stability and bearing capacity of the precast pier are further enhanced. Due to the use of prestressed FRP bars to achieve self-centering ability, the pier can automatically rebound after an earthquake without major repairs or demolition and reconstruction, reducing the later carbon expenditure.

[0019] Among them, a cushion block 7 is arranged in the groove on the upper surface of the bearing platform 2, and the cushion block is embedded in the alkali-activated recycled aggregate concrete 3. The cushion block 7 serves as an early support unit in the connection area, providing a certain operating space for construction, and dispersing the local stress during the tensioning of the prestressed steel bars and the load transfer, reducing stress concentration. In addition, the cushion block 7 has a certain roughness, forming a good mechanical interlocking effect with the alkali-activated recycled aggregate concrete, enhancing the bonding performance, and thus improving the shear strength of the interface.

[0020] Among them, the material of the prestressed FRP bars is carbon fiber reinforced composite material. By pre-applying prestress, the precast pier using this material has a better ability to return to the initial state after being subjected to external forces.

[0021] The construction technology of the prestressed FRP bar self-centering precast pier structure of the present invention (1), precast a bearing platform with a groove on the upper surface, a counterbore on the lower surface, and a through hole in the center; (2), precast a precast pier body with a counterbore on the upper surface and a through hole in the center; (3), prepare alkali-activated recycled aggregate concrete; (4), vertically penetrate FRP bars through the through hole of the precast bearing platform from bottom to top. The first end anchor head of the FRP bars is limited in the counterbore on the lower surface of the bearing platform, and the second end of the FRP bars extends out of the groove on the upper surface of the bearing platform; (5), place a cushion block in the groove on the upper surface of the bearing platform and pour alkali-activated recycled aggregate concrete. Then, the second end of the FRP bars is vertically penetrated through the through hole from the bottom to the top of the precast pier body, so that the second end of the FRP bars penetrates out of the counterbore on the upper surface of the precast pier body, and the precast pier body is vertically placed above the cushion block in the groove; (6), use a tensioning tool to tension the second end of the FRP bars and use a tensioning end anchor to anchor in the counterbore on the upper surface of the precast pier body.

[0022] By introducing FRP bars into the pier structure and applying prestress, the present invention can achieve the self-centering function, thereby improving the seismic performance of the structure. Moreover, the structure is simple, the construction is convenient and fast, which is beneficial to shortening the construction period and cost. By setting alkali-activated recycled aggregate concrete in the groove on the upper surface of the pier cap, construction waste can be effectively utilized, and the durability and green environmental protection performance of the concrete can be improved. Therefore, the present invention can improve the seismic and anti-fatigue performance of the assembled pier structure, extend the service life of the structure, and at the same time achieve energy conservation, emission reduction and sustainable development.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the specific implementation manners of the present invention can still be modified or some technical features can be equivalently replaced without departing from the spirit of the technical solutions of the present invention, and they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A prestressed FRP tendon self-resetting assembled pier structure, characterized in that: It includes a cap, alkali-activated recycled aggregate concrete arranged in a groove on the upper surface of the cap, and a prefabricated pier body arranged in the alkali-activated recycled aggregate concrete. The cap, alkali-activated recycled aggregate concrete and the prefabricated pier body are provided with through holes arranged along the length direction and facing each other. Prestressed FRP tendons are arranged in the through holes. The first end of the prestressed FRP tendons is anchored in a countersunk hole on the lower surface of the cap, and the second end of the prestressed FRP tendons is anchored in a countersunk hole on the upper surface of the prefabricated pier body. By pre-applying prestress to the prestressed FRP tendons, the assembled pier can be restored to its initial state after being subjected to external force.

2. The prestressed FRP tendon self-resetting assembled pier structure according to claim 1 is characterized in that: A cushion block is arranged in the groove on the upper surface of the cap, and the cushion block is embedded in the alkali-activated recycled aggregate concrete.

3. The prestressed FRP tendon self-resetting assembled pier structure according to claim 1 or 2, characterized in that: The material of the prestressed FRP tendons is carbon fiber reinforced composite material.

4. The prestressed FRP tendon self-resetting assembled pier structure according to claim 3 is characterized in that: The alkali-activated recycled aggregate concrete comprises construction waste recycled aggregate, sand, fly ash, slag, alkaline activator and water.

5. A construction process for a prestressed FRP tendon self-resetting assembled pier structure, characterized in that: (1) A prefabricated cap having a groove on the upper surface, a countersunk hole on the lower surface, and a through hole in the center; (2) A prefabricated pier body with a countersunk hole on the upper surface and a through hole in the center; (3) Prepare alkali-activated recycled aggregate concrete; (4) FRP bars are inserted from bottom to top in the through hole of the prefabricated cap, with the first end of the FRP bar anchored in the countersunk hole on the lower surface of the cap, and the second end of the FRP bar extends out of the groove on the upper surface of the cap; (5) Place a pad in the groove on the upper surface of the cap and pour alkali-activated recycled aggregate concrete. Then, pass the second end of the FRP bar through the through hole from the bottom to the top of the prefabricated pier body, so that the second end of the FRP bar passes through the countersunk hole on the upper surface of the prefabricated pier body, and vertically place the prefabricated pier body above the pad in the groove; (6) Use the tensioning tool to tension the second end of the FRP tendon and use the tensioning end anchor to anchor it in the countersunk hole on the upper surface of the precast pier.

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