Lap joint device and lap joint method for FRP rib winding

Abstract

The invention discloses a lap joint device and method for FRP rib winding, and belongs to the technical field of prestressed composite material application, the device comprises a sleeve, a clamping piece and a connector, the inner surface of the sleeve is provided with taper, the outer surface of the sleeve is provided with curvature radius, and the rear end of the sleeve is provided with internal threads; the clamping piece is composed of three piece bodies, the inner diameter is slightly smaller than the diameter of the FRP rib, and the outer surface is provided with taper to form taper difference with the sleeve. One end of the joint is in threaded connection with the sleeve; the lap joint method comprises the steps that the clamping piece wraps the FRP rib to be inserted into the sleeve and anchored, and lap joint is completed through connection of the connector and the lock chain. According to the lapping device and method for FRP rib winding, the structure is simple, anchoring is reliable, construction is convenient and fast, and the lapping device and method are suitable for FRP rib prestress winding engineering.

Description

An overlapping device and method for FRP rebar winding Technical Field

[0001] This invention belongs to the field of prestressed composite material application technology, specifically an overlapping device and method for FRP bar winding. Background Technology

[0002] In modern civil engineering structural reinforcement, fiber-reinforced polymer (FRP) bars have gradually become an ideal replacement for traditional steel bars due to their advantages such as high strength, corrosion resistance, lightweight, and high design flexibility. In prestressed structures, applying prestress to FRP bars can effectively improve the crack resistance and load-bearing capacity of the structure, extending its service life. In practical engineering applications, FRP bars are often used to reinforce structures such as cylinders and pipes by winding them together to construct a ring-shaped prestressed system. However, due to the limited length of FRP bars at the factory and the need to ensure reliable connections between the bars during the winding process to maintain effective prestress transfer, the lap splicing and anchoring of FRP bars during winding have become key technical challenges.

[0003] Currently, existing FRP (Fiberglass Reinforced Plastic) rebar anchoring technologies are mainly divided into two categories: clamp-type anchors and bonded anchors. Clamp-type anchors rely on clamps to apply circumferential pressure to the FRP rebar for anchoring, but under high stress, they are prone to shearing effects, leading to shear failure of the FRP rebar. Bonded anchors use adhesives such as resin to bond the FRP rebar to a metal sleeve, and apply prestress after the adhesive cures. However, the creep problem of the adhesive leads to a decrease in anchoring performance over time, and the curing time of the adhesive is not conducive to on-site construction. The various anchors currently used cannot meet the engineering requirements for tensioning and lap splicing of FRP rebar during prestressed winding.

[0004] In terms of FRP (fiberglass reinforced plastic) bar lap splicing, traditional methods such as tying, welding, and mechanical connection are difficult to apply due to the inherent brittleness, anisotropy, and non-weldability of FRP bars. Existing lap splicing methods have significant shortcomings in prestress transfer efficiency, ease of winding construction, and long-term structural stability. This results in FRP bar prestressed structures failing to fully utilize the material's performance advantages, thus limiting the widespread application of FRP bars in prestressed winding engineering.

[0005] In conclusion, there is an urgent need to develop a dedicated lap splicing device and method for the winding construction of prestressed FRP bars, in order to overcome the shortcomings of existing technologies in terms of anchorage reliability, lap splicing efficiency, and construction convenience, and to promote the further development of FRP bar prestressing technology in the field of civil engineering. Summary of the Invention

[0006] To address the technical problems existing in the prior art, the present invention provides an overlapping device for FRP bar winding, which has high interception efficiency, strong synergy, and is adaptable to multiple scenarios.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] An overlapping device for FRP (fiberglass reinforced plastic) rebar winding includes an FRP rebar, clamps, a sleeve, a connector, and a chain. The sleeve has a tapered inner surface and an outer surface with a radius of curvature consistent with the winding structure radius. The inner surface of the rear end has a thread. There are three clamps, the inner surface diameter of which is smaller than the diameter of the FRP rebar, and the outer surface has a tapered shape, forming a tapered difference with the inner surface of the sleeve. A gap is reserved between the three clamps. One end of the connector has an external thread that connects to the rear end of the sleeve, and the other end connects to the chain.

[0009] As a further step in the above technical solution:

[0010] Preferably, the taper of the inner surface of the sleeve is consistent along the axial direction.

[0011] Preferably, the radius of curvature of the outer surface of the sleeve is the same as the radius of the winding wheel.

[0012] Preferably, the taper of the outer surface of the clip is greater than the taper of the inner surface of the sleeve.

[0013] Preferably, the gap between the clips is 0.1 mm.

[0014] This invention also discloses a method for lap splicing FRP reinforcement, which uses the above-mentioned lap splicing device to perform the lap splicing, and includes the following steps:

[0015] The lap splicing device and method for FRP rebar winding provided by this invention have the following advantages compared with the prior art:

[0016] The lap splicing device and method for FRP rebar winding of the present invention achieve reliable anchoring through the tapered fit between the sleeve and the clamp, preventing slippage or shear failure of the FRP rebar under prestress. The outer surface curvature of the sleeve of the present invention is consistent with the winding structure, preventing rebar bending and improving structural durability. The present invention uses threaded joints and chain connections, facilitating rapid on-site installation and adjustment, resulting in high construction efficiency. The device of the present invention has a simple structure, wide applicability, and can be used in various FRP rebar prestressed winding projects. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the overlapping device of the present invention.

[0018] Figure 2 is a schematic diagram of the connection position structure of the overlapping device when the present invention is applied.

[0019] Figure 3 is a schematic diagram of the structure of the sleeve of the present invention.

[0020] Explanation of the labels in the diagram:

[0021] 1. FRP rib; 2. Clamping plate; 3. Sleeve; 301. Outer curvature; 302. Internal taper; 303. Internal thread; 4. Joint; 5. Chain. Detailed Implementation

[0022] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0023] Figures 1 to 3 illustrate an embodiment of an overlapping device for FRP bar winding according to the present invention, comprising FRP bar 1, clamp 2, sleeve 3, connector 4, and chain 5.

[0024] In this embodiment, the inner surface of the sleeve 3 is provided with a taper 302, which is consistent along the axial direction. The outer surface of the sleeve 3 is provided with a radius of curvature 301, the value of which is consistent with the radius of the winding structure, preferably 0.6m. The inner surface of the rear end of the sleeve 3 is provided with an internal thread 303, the thread length of which is preferably 10mm.

[0025] In this embodiment, the inner surface of the sleeve has a taper of 1°, the sleeve has a uniform thickness on the same axial plane, the thickness at the anchoring front end is 2.52 mm, the thickness at the rear end is 2 mm, and the length is 30 mm.

[0026] In this embodiment, three clamping pieces 2 are provided. Each clamping piece is arc-shaped, and the inner diameter of the clamping piece is slightly smaller than the diameter of the FRP reinforcement. For example, when the FRP reinforcement diameter is 5mm, the inner diameter of the clamping piece is 4.7mm. The outer surface of the clamping piece has a taper, preferably 1.6°, forming a 0.6° taper difference with the taper of the inner surface of the sleeve. The taper of the clamping piece is greater than the taper of the inner surface of the sleeve. A 0.1mm gap is reserved between the three clamping pieces to prevent them from contacting each other, reducing the preload applied to the FRP reinforcement and lowering the anchoring efficiency.

[0027] In this embodiment, the clamping piece is 30mm long and is used in conjunction with the sleeve for anchoring.

[0028] In this embodiment, one end of the connector 4 is provided with an external thread, which mates with the internal thread 303 at the rear end of the sleeve, and the other end is connected to the chain 5.

[0029] The present invention provides a method for lap splicing FRP (fiberglass reinforced plastic) reinforcing bars, comprising the following steps:

[0030] Step S1: Wrap the end of the FRP bar 1 with three clips 2 and insert it into the sleeve 3.

[0031] Step S2: Use a hydraulic pump jack with a built-in reaction frame to press the clamp 2 into the sleeve 3 to achieve the anchoring of the FRP reinforcement.

[0032] Step S3: Connect the two connectors 4 to the two ends of the chain 5 respectively.

[0033] Step S4: Screw the two connectors 4 into the threaded holes at the rear ends of the two sleeves 3 with installed FRP bars to complete the lap joint.

[0034] During prestressed winding, the carbon fiber reinforcement at the lap joint will exhibit a curvature difference at the anchorage tip due to the thickness and length of the anchorage itself. Because of the poor shear resistance of the carbon fiber composite reinforcement, the end position may bend and fail due to the curvature difference and tensile force. The new small anchorage sleeve is five times shorter and about three times smaller in outer diameter than the traditional wedge-type anchorage, significantly reducing the possibility of shear failure at the anchorage tip during carbon fiber reinforcement winding at the lap joint. Simultaneously, increasing the taper difference between the wedge and the sleeve improves anchorage efficiency, allowing the applied prestress to be maintained.

[0035] The above embodiments are merely preferred examples of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. An lap splicing device for FRP bar winding, characterized in that, The device includes FRP ribs, clamps, sleeves, connectors, and chains. The inner surface of the sleeve is tapered, and the outer surface has a radius of curvature consistent with the radius of the winding structure. The inner surface of the rear end is threaded. There are three clamps. The inner surface diameter of each clamp is smaller than the diameter of the FRP rib, and the outer surface is tapered, forming a tapered difference with the inner surface of the sleeve. A gap is reserved between the three clamps. One end of the connector is threaded and connected to the rear end of the sleeve, and the other end is connected to the chain.

2. The lap splice device for FRP rebar winding according to claim 1, characterized in that, The taper of the inner surface of the sleeve is consistent along the axial direction.

3. The lap splice device for FRP rebar winding according to claim 1, characterized in that, The radius of curvature of the outer surface of the sleeve is the same as the radius of the winding wheel.

4. The lap splice device for FRP rebar winding according to claim 2, characterized in that, The taper of the outer surface of the clamp is greater than the taper of the inner surface of the sleeve.

5. The lap splice device for FRP rebar winding according to claim 1, characterized in that, The gap between the clips is 0.1 mm.

6. A method for winding and overlapping FRP reinforcement, characterized in that, The overlapping device according to any one of claims 1 to 5 is used to perform the overlapping, which includes the following steps: Step S1, wrapping the end of the FRP bar with three clamps and inserting it into the sleeve; Step S2, using a hydraulic pump jack with a built-in reaction frame to anchor the clamps into the sleeve; Step S3, connecting the two joints to the two ends of the chain respectively; Step S4, screwing the two joints into the threaded holes at the rear ends of the two sleeves respectively to complete the overlapping of the FRP bar.

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