Pre-tensioning method CFRP bar concrete hollow slab, tensioning anchorage device and construction method

Abstract

The invention discloses a pre-tensioning method CFRP rib concrete hollow slab, a tensioning anchorage device and a construction method.The pre-tensioning method CFRP rib concrete hollow slab comprises CFRP embossed ribs, a framework structure, spiral ribs, PVC pipes, cushion blocks and concrete, the cushion blocks are arranged on the lower sides of bottom plate steel bars and the outer sides of vertical steel bars on the two sides respectively, and the CFRP embossed ribs are distributed at equal intervals, arranged in the framework structure and used for tensioning the framework structure; the spiral ribs penetrate through the prestressed CFRP embossed ribs and then are placed at the two ends of the bonding sections of the prestressed CFRP embossed ribs, the PVC pipes penetrate through the prestressed CFRP embossed ribs and then are placed at the two ends of the prestressed CFRP embossed ribs, unbonded sections are formed, concrete is poured on the periphery of the framework structure in cooperation with a mold after the CFRP embossed ribs are tensioned, the mold is dismantled after the concrete is formed, and the prestressed CFRP embossed ribs are formed. And the pre-tensioning method CFRP bar concrete hollow slab structure is formed. According to the scheme, the CFRP embossed ribs can be reliably bonded with concrete under high prestress, and bonding slippage failure is avoided. And secondly, provided anchoring is reliable, and shear damage of the CFRP ribs during tensioning is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a pre-tensioned CFRP reinforced concrete hollow slab, a tensioning anchor and a construction method. Background Art

[0002] With the advancement of technology, CFRP bars have begun to replace steel bars in concrete structures, forming CFRP bar concrete structures. However, since CFRP bars have lower compressive and shear strengths than tensile strengths, they are prone to compression and shear failure in concrete structures, resulting in a very low utilization rate of the tensile strength of CFRP bars, and the advantages of CFRP bars cannot be brought into play. Prestressed CFRP bar concrete structures can give full play to the high tensile strength of CFRP bars, and are a structural form in which CFRP bars and concrete are well combined.

[0003] Therefore, it is now necessary to provide a pre-tensioned CFRP reinforced concrete hollow slab structure to solve the above technical problems, which is a problem that needs to be solved in the art. Summary of the invention

[0004] In view of the technical problem that the existing CFRP bars in concrete structures are prone to compression and shear failure, resulting in a very low utilization rate of the tensile strength of the CFRP bars, the purpose of the present invention is to provide a pre-stressed CFRP bar concrete hollow slab structure, which has a high structural bearing capacity, good structural durability, and a lightweight structure, which can reduce carbon emissions and subsequent maintenance costs. On this basis, a tensioning anchor is also provided to realize the construction method of the pre-stressed CFRP bar concrete hollow slab, which effectively overcomes the problems existing in the prior art.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a pre-tensioned CFRP reinforced concrete hollow slab, comprising: CFRP embossed bars, a skeleton structure, spiral bars, PVC pipes, pads and concrete, wherein the pads are respectively placed on the lower side of the bottom plate steel bars and the outer side of the vertical steel bars on both sides, the CFRP embossed bars are equidistantly distributed and placed in the skeleton structure and tensioned, the spiral bars are inserted into the prestressed CFRP embossed bars and then placed at both ends of the prestressed CFRP embossed bars bonding section, the PVC pipe is inserted into the prestressed CFRP embossed bars and then placed at both ends of the prestressed CFRP embossed bars to form a non-bonded section, after the CFRP embossed bars are tensioned, concrete is cast in cooperation with a mold on the periphery of the skeleton structure, and after the concrete is formed, the mold is removed to form a pre-tensioned CFRP reinforced concrete hollow slab structure.

[0006] Furthermore, the skeleton structure includes top plate steel bars, vertical steel bars and bottom plate steel bars, wherein the bottom plate steel bars and the top plate steel bars are equidistantly distributed along the length direction of the hollow plate structure, and the vertical steel bars are arranged between the top plate steel bars and the bottom plate steel bars and are connected to the top plate steel bars and the bottom plate steel bars at both ends to form a steel cage.

[0007] Furthermore, the surface of the CFRP embossed rib is provided with ribs formed by applying circumferential pressure during pultrusion of the CFRP rib.

[0008] In order to achieve the above-mentioned object, the present invention provides a tensioning anchor, which is arranged at both ends of the CFRP embossed bars in the pre-tensioned CFRP bar concrete hollow slab.

[0009] Furthermore, the tension anchor comprises an outer membrane sleeve and an inner membrane clip, wherein the inner membrane clip is arranged in the outer membrane sleeve and is integrally sleeved on both ends of the CFRP embossed rib to preliminarily tighten the CFRP embossed rib.

[0010] Furthermore, the two ends of the outer membrane sleeve are respectively a tensioning end and a connecting end, the interior of the tensioning end is an inverted cone, and the connecting end is a hollow sleeve with an internal thread.

[0011] Furthermore, the inner membrane clip is an inverted cone-shaped three-petal clip, and its length is consistent with the length of the tensioning end of the outer membrane sleeve.

[0012] Furthermore, the tensioning anchor is also provided with a pre-tightening tool, which includes an outer diameter adjustment tube, an ejector rod and a hand-lift pump connecting end. The outer diameter adjustment tube cooperates with the outer membrane sleeve, the outer membrane sleeve is inserted into the outer diameter adjustment tube, the ejector rod is placed in the threaded inner hole of the outer membrane sleeve, and then the whole is placed in the mold cavity of the tightening tool and arranged opposite to the hand-lift pump connecting end. The hand pump is connected through the hand-lift pump connecting end, and the hand pump is operated to push the cylinder piston out to tighten the inner and outer molds.

[0013] Furthermore, the connecting end of the outer membrane sleeve is provided with a tensioning device, and the tensioning device includes a connecting sleeve, a steel strand anchor and a tensioning pedestal. Both ends of the connecting sleeve are threaded, one end is connected to the connecting end of the outer membrane sleeve, and the other end is connected to the steel strand anchor. The tensioning pedestal is provided with an anchoring end and a tensioning end, and the steel strands on both sides are respectively fixed to the anchoring end and the tensioning end of the tensioning pedestal. The tensioning end is provided with a jack, and the jack at the tensioning end is operated to push out to tension the CFRP embossed ribs. After the tensioning is completed, concrete is poured on the hollow slab structure.

[0014] In order to achieve the above object, the present invention provides a construction process of a pre-tensioned CFRP reinforced concrete hollow slab, which is based on setting the above-mentioned tensioning anchors at both ends of the CFRP embossed bars and cooperating with tensioning equipment to complete the construction of the pre-tensioned CFRP reinforced concrete hollow slab. The construction method includes the following steps:

[0015] Step 1: The bottom plate steel bars and vertical steel bars are tied and formed by tying wire according to the design drawings and placed on the tensioning pedestal;

[0016] Step 2: Place the pads on the lower side of the bottom plate reinforcement and on the outer side of the vertical reinforcements on both sides;

[0017] Step 3: After the spiral ribs and PVC tubes are inserted into the CFRP embossed ribs, the ends of the CFRP embossed ribs are sequentially passed through the outer mold cone holes and the outer cone inner mold clips, and the inner and outer molds are preliminarily tightened manually;

[0018] Step 4: Put the outer mold into the outer diameter adjustment tube), put the ejector rod into the threaded inner hole of the outer mold, and then put the whole into the cavity of the tightening tool. Operate the hand pump by hand to push the cylinder piston out to tighten the inner and outer molds;

[0019] Step 5: The CFRP embossed reinforcement tensioning anchor is connected to the steel strand anchor through the connecting sleeve, and the steel strands on both sides are fixed to the anchor end and the tensioning end of the tensioning pedestal respectively;

[0020] Step 6: Operate the tensioning control device, and the tensioning end jack tensions the CFRP embossed ribs;

[0021] Step 7: Place a cross-bracing stirrup at one-third of the span at the bottom of the hollow slab structure, place a core mold on the stirrup, lay the top plate steel bars above the core mold, and form a steel cage with the vertical steel bars through binding wires;

[0022] Step 8: Place the end form and side form at the end and side of the steel cage respectively, connect the two by bolts to form a whole, and then start pouring concrete;

[0023] Step 9: After the prestressed CFRP embossed ribs are released, the CFRP embossed ribs at both ends of the hollow slab are cut off;

[0024] Step 10: After the concrete has been cured for 28 days, remove the mold and complete the production of the pre-stressed CFRP reinforced concrete hollow slab.

[0025] The pre-stressed CFRP tendon concrete hollow slab, tensioning anchor and construction method provided by the present invention firstly adopt prestressed CFRP tendons in prestressed concrete components. Compared with the pre-stressed steel strand concrete hollow slab, the structural bearing capacity is higher, the structural durability is better, and the structure is lightweight, which can reduce carbon emissions and subsequent maintenance costs.

[0026] The CFRP embossed ribs used at the same time can solve the problem of bonding with concrete and avoid bond slip failure.

[0027] Secondly, the CFRP embossed bar tensioning anchor provided in this solution can ensure the reliable anchoring of the CFRP bar, and will not cause slippage or shear failure of the CFRP bar during the tensioning process.

[0028] Finally, this proposal also provides a construction method for pre-stressed CFRP reinforced concrete hollow slabs, providing guidance for the industrialized production of pre-stressed CFRP reinforced concrete structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0030] Figure 1 This is the cross-sectional view of the pre-tensioned CFRP reinforced concrete hollow slab structure;

[0031] Figure 2 It is a three-dimensional schematic diagram of the pre-tensioned CFRP reinforced concrete hollow slab structure;

[0032] Figure 3 This is a schematic diagram of the CFRP reinforcement tightening tooling in the pre-tensioned CFRP reinforcement concrete hollow slab structure.

[0033] Figure 4 Schematic diagram of the connection between CFRP bars and steel strands in the pre-tensioned CFRP reinforced concrete hollow slab structure.

[0034] Figure 5 This is the construction schematic diagram of the pre-stressed CFRP reinforced concrete hollow slab structure.

[0035] The following is a description of the components in the accompanying drawings:

[0036] 1. Concrete 2. CFRP embossed bars 3-1 Bottom plate steel bars 3-2. Vertical steel bars 3-3. Top plate steel bars 4. Spiral bars 5. PVC pipes 6. Spacers 7. Stirrups 8. Tension anchors 9. Inner membrane clips 10. Outer membrane sleeves 11. Connecting sleeves 13. Outer diameter adjustment tubes 14. Ejector rods 15. Hand pumps 16. Anchoring ends 17. Tensioning ends 18. Jacks 19. End molds 20. Side molds 21. Core molds 22. Strand anchors. DETAILED DESCRIPTION

[0037] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0038] In view of the technical problem that the existing CFRP bars are prone to compression and shear failure in concrete structures, resulting in a very low utilization rate of the tensile strength of the CFRP bars, the present invention provides a pre-tensioned CFRP bar concrete hollow slab structure, which has a high structural bearing capacity, good structural durability, and a lightweight structure, and can reduce carbon emissions and subsequent maintenance costs. On this basis, a tensioning anchor that matches it is also provided, which can ensure the reliable anchoring of the CFRP bars, and will not slip or cause shear failure of the CFRP bars during the tensioning process, thereby effectively overcoming the problems existing in the prior art.

[0039] See also Figure 1-Figure 2 The pre-tensioned CFRP reinforced concrete hollow slab structure comprises CFRP embossed reinforcement 2, a skeleton structure, spiral reinforcement 4, a PVC pipe 5, a spacer 6 and concrete 1.

[0040] The skeleton structure is composed of a steel bar assembly, which includes a top plate steel bar 3-3, a vertical steel bar 3-2 and a bottom plate steel bar 3-1, wherein the bottom plate steel bar 3-1 and the top plate steel bar 3-2 are equidistantly distributed along the length direction of the hollow plate structure, and the vertical steel bar 3-2 is arranged between the top plate steel bar 3-3 and the bottom plate steel bar 3-1 and the two ends are respectively connected to the top plate steel bar 3-3 and the bottom plate steel bar 3-1 to form a steel cage.

[0041] The pads 6 are respectively placed on the lower side of the bottom plate reinforcement 3--1 and the outer side of the vertical reinforcement 3-2 on both sides, which are used to prevent the reinforcement from being closely attached to the formwork during pouring, resulting in the reinforcement being exposed after the pouring is completed.

[0042] The pad 6 in this scheme is preferably shaped like a plum blossom, and the middle of the plum blossom-shaped pad is a hollow structure, which can be inserted into the steel bars when tying the steel cage. At the same time, the pads are preferably placed every 80 cm along the length of the hollow slab to ensure the thickness of the protective layer of the pre-stressed CFRP reinforced concrete hollow slab.

[0043] The CFRP embossed bars 2 are used as prestressed bars, which are equidistantly distributed and placed in the steel bar assembly. The CFRP embossed bars in this solution are used as prestressed bars for the prestressed CFRP bar concrete hollow slab structure. The bar material is preferably in the form of ribs on the surface. The ribs are formed by applying circumferential pressure during the pultrusion of the CFRP bars to ensure the bonding strength between the prestressed CFRP bars and the concrete.

[0044] The spiral reinforcement 4 is inserted into the prestressed CFRP embossed reinforcement 2 and then placed at both ends of the concrete hollow slab. The configuration of the spiral reinforcement 4 can improve the local compressive strength of the end concrete and prevent the end concrete from cracking.

[0045] According to the requirements of structural reinforcement, the diameter of the spiral reinforcement should be 6-8mm, preferably 6mm, and the length should be 15-20mm, preferably 20mm. The diameter and length increase with the increase of prestress.

[0046] The PVC tube 5 is placed on the prestressed CFRP embossed ribs 2 and then placed at both ends of the hollow slab to form a non-bonded section. The PVC tube is configured to adjust the arch height in the middle of the hollow slab to ensure that the arch height is within the specification limit. The diameter of the PVC tube 5 is preferably slightly larger than the prestressed CFRP embossed ribs 2 to ensure that the PVC can be smoothly inserted into the CFRP embossed ribs.

[0047] The length is controlled according to the arch height of the CFRP reinforced concrete hollow slab structure. The length of the PVC pipe is the length of the unbonded section of the CFRP embossed reinforcement 2. The longer the unbonded section, the greater the stress of the bonded section of the CFRP embossed reinforcement 2, which increases the arch height of the hollow slab. The length arrangement principle of the PVC pipe is that the CFRP embossed reinforcement on both sides is the shortest, and the CFRP embossed reinforcement PVC pipe in the middle of the span is the longest.

[0048] The above-mentioned CFRP embossed ribs 2, steel bar components, spiral ribs 4, PVC pipes 5, and pads 6 cooperate to form the skeleton of the entire hollow slab structure, and then concrete 1 is poured in a mold around the outer periphery of the skeleton structure formed by the above scheme. After the concrete 1 is formed, the mold is removed to form a pre-tensioned CFRP reinforced concrete hollow slab structure.

[0049] Furthermore, the tension anchor 8 provided in this solution is a reusable clip-type anchor, which is arranged at both ends of the CFRP embossed rib 2, and can ensure reliable anchoring of the CFRP rib, and will not slip during the tensioning process of the CFRP embossed rib 2 before pouring, nor will it cause shear damage to the CFRP rib 2. The tension anchor 8 includes an outer membrane sleeve 10 and an inner membrane clip 9.

[0050] The connecting end of the outer membrane sleeve 10 is a hollow sleeve with an internal thread. The interior of the tensioning end of the outer membrane sleeve 10 is an inverted cone, and its diameter gradually increases along the port end assembled relative to the CFRP embossed rib 2. The inner membrane clip 9 is an inverted cone 3-petal clip, which is assembled inside the outer membrane sleeve and is used to generate friction and clamp the CFRP embossed rib 2 to ensure the reliability of the anchoring of the CFRP embossed rib 2.

[0051] When the CFRP embossed rib 2 is passed through the tapered hole of the outer membrane sleeve 10 and the outer cone inner mold clip in sequence, as it goes deeper, the extrusion pressure on the CFRP embossed rib 2 becomes greater and greater because the diameter of the tapered hole of the outer membrane sleeve 10 and the outer cone inner mold clip becomes smaller and smaller, so the CFRP embossed rib 2 can be anchored.

[0052] After the spiral rib 4 and the PVC tube 5 are inserted into the CFRP embossed rib, the end of the CFRP embossed rib 2 is passed through the tapered hole of the outer membrane sleeve 10 and the outer cone inner mold clip 9 in turn, and exceeds the plane part of the inner mold. The CFRP embossed rib 2 is manually pulled. The friction force provided by the anchor is greater than the tension force, so that it is initially tightened with the inner and outer molds to ensure reliable anchoring.

[0053] It should be noted here that the present solution preferably chamfers the end of the CFRP embossed rib 2 after the spiral rib 4 and the PVC tube 5 are inserted into the CFRP embossed rib 2. The sharp edge or irregular shape of the end of the CFRP embossed rib 2 is processed into a smooth slope or arc by chamfering. When the end contacts the inner membrane clip, it is not easy to get stuck, thereby reducing the friction resistance during the assembly process and making it easier to slide into the inner membrane clip 9.

[0054] In order to further ensure the tension between the outer membrane sleeve 10 and the inner membrane clip 9, the tension anchor 8 is also equipped with a pre-tightening tool, see Figure 3 The pre-tightening tooling includes an outer diameter adjustment tube 13, an ejector rod 14 and a hand-lift pump connecting end 15.

[0055] The outer diameter adjustment tube 13 cooperates with the outer membrane sleeve 10, and the outer membrane sleeve 10 is inserted into the outer diameter adjustment tube 13, and the ejector rod 14 is placed in the threaded inner hole of the outer membrane sleeve 10, and then the whole is placed in the cavity of the jacking tool and arranged opposite to the hand-lifting pump connection end 15. The hand-pressing pump is connected through the hand-lifting pump connection end 15, and the hand-pressing pump is operated to push the cylinder piston out. The piston pushes out and generates an axial thrust. This force is transmitted to the contact interface between the inner membrane clip 9 and the outer membrane sleeve 10 through the ejector rod 14, so that the inner membrane clip 9 can gradually fit the inner wall of the outer membrane when ejecting. Then take out the outer diameter adjustment tube 13 and the ejector rod 14 in turn.

[0056] After the inner and outer membranes arranged at the end of the CFRP embossed rib are tightened, they are placed in the tensioning equipment, and the end of the CFRP embossed rib 2 is tensioned by the tensioning equipment, so that the concrete 1 is poured after the tensioning is completed. The CFRP bar concrete hollow slab structure thus formed has a higher structural bearing capacity and better structural durability than the pre-tensioned steel strand concrete hollow slab. It is also lightweight and can reduce carbon emissions and subsequent maintenance costs.

[0057] Here, the tensioning device includes a connecting sleeve 11, a steel strand anchor 22 and a tensioning pedestal, and the CFRP tendon tensioning anchor 22 is connected to the tensioning device through the connecting sleeve 11.

[0058] See also Figure 4 The connecting sleeve 11 is threaded at both ends, one end of which is connected to the CFRP tendon tensioning anchor 8, and the other end of which is connected to the steel strand anchor 22.

[0059] The tensioning platform is provided with an anchoring end 16 and a tensioning end 17 , and the steel strands 22 at both sides are fixed to the anchoring end 16 and the tensioning end 17 of the tensioning platform respectively.

[0060] The tensioning end 17 is equipped with a jack 18. The tensioning control device is operated to push out the tensioning end jack 18 to tension the CFRP embossed ribs 2. After the tensioning is completed, concrete is poured on the hollow slab structure.

[0061] Based on the tensioning anchor and tensioning equipment provided in the above scheme, this scheme also provides the construction steps of the pre-tensioned CFRP reinforced concrete hollow slab, see Figure 5 The specific construction steps are as follows:

[0062] Step 1: The bottom plate steel bars 3-1 and the vertical steel bars 3-2 are tied together by tying wires according to the design drawings and placed on the tensioning pedestal;

[0063] Step 2: Place the pads on the lower side of the bottom plate reinforcement 3-1 and the outer side of the vertical reinforcement 3-2 on both sides;

[0064] Step 3: After the spiral rib 4 and the PVC tube 5 are inserted into the CFRP embossed rib, the end of the CFRP embossed rib is passed through the tapered hole of the outer mold 9 and the outer cone inner mold clip 10 in sequence, and the inner and outer molds are preliminarily tightened manually;

[0065] Step 4: Put the outer mold into the outer diameter adjustment tube 13, put the ejector rod 14 into the threaded inner hole of the outer mold, and then put the whole into the cavity of the tightening tool. Operate the hand pump 15 by hand to push the cylinder piston out and tighten the inner and outer molds.

[0066] Step 5: The CFRP embossed bar tensioning anchor is connected to the steel strand anchor 22 via the connecting sleeve 11, and the steel strands on both sides are fixed to the tensioning pedestal anchor end 16 and the tensioning end 17 respectively.

[0067] Step 6: operate the tensioning control device, and the tensioning end jack 18 tensions the CFRP embossed rib 2;

[0068] Step 7: Place a cross-bracing stirrup 7 at one-third of the span at the bottom of the hollow slab structure, place a core mold 21 on the stirrup, lay the top plate steel bars 3-3 above the core mold 21, and form a steel cage with the vertical steel bars 3-2 through binding wires.

[0069] Step 8: Place the end form 19 and the side form 20 at the end and side of the steel cage respectively, connect the two by bolts to form a whole, and then start pouring concrete.

[0070] Step 9: After the prestressed CFRP embossed ribs are stretched, the CFRP embossed ribs 2 at both ends of the hollow slab are cut off.

[0071] Step 10: After the concrete has been cured for 28 days, remove the mold and complete the production of the pre-stressed CFRP reinforced concrete hollow slab.

[0072] Based on the construction steps of the pre-tensioned CFRP reinforced concrete hollow slab provided by the above scheme, the following examples illustrate the construction steps of the pre-tensioned CFRP reinforced concrete hollow slab. The specific construction steps are as follows:

[0073] Step 1: Tie the bottom plate steel bars 3-1 and the vertical steel bars 3-2 into shape by tying wire according to the design drawings and place them on the tensioning pedestal;

[0074] Step 2: Place the pads on the lower side of the bottom plate reinforcement 3-1 and the outer side of the vertical reinforcement 3-2 on both sides, and place them every 80 cm along the length of the hollow slab;

[0075] Step 3: Install the prestressed CFRP embossed rib tensioning anchor: First, insert the spiral rib 4 and the PVC tube 5 into the CFRP embossed rib, then chamfer the end of the CFRP embossed rib 2 to facilitate installation into the inner mold, and then pass the end of the CFRP embossed rib through the tapered hole of the outer mold 9 and the outer cone inner mold clip 10 in turn, and extend about 5mm beyond the inner mold plane, and manually tighten the inner and outer molds preliminarily.

[0076] Step 4: Tighten the CFRP tendon tensioning anchor 8: Put the outer mold into the outer diameter adjustment tube 13, put the ejector rod 14 into the threaded inner hole of the outer mold, and then put the whole into the cavity of the tightening tool. Connect the hand pump through the hand pump connection end 15, operate the hand pump to push the oil cylinder piston out, tighten the inner and outer molds, and the pressure gauge reading is about 40Mpa-45Mpa. Loosen the oil pump, and the oil cylinder piston automatically retracts. Take out the outer diameter adjustment tube 13 and the ejector rod 14 in turn.

[0077] Step 5: The CFRP embossed rib 2 is connected to the tensioning pedestal, the CFRP embossed rib tensioning anchor 8 is connected to the connecting sleeve 11, and the other side of the connecting sleeve 11 is connected to the steel strand anchor 13, and the connection length must be more than 8 cm. The steel strands 22 on both sides are fixed to the tensioning pedestal anchor end 16 and the tensioning end 17 respectively.

[0078] Step 6: Tension the CFRP embossed ribs 2, operate the tensioning control equipment, push out the jack 18 at the tensioning end, and stop tensioning when the prestressing reaches 5%. Observe whether each prestressed CFRP embossed rib 2 remains in the tensioned state. After the inspection is completed, continue tensioning. Load in four levels according to 30%, 60%, 90%, and 100%. The four-level loading can reduce the friction and loss between the CFRP embossed ribs 2 and the tensioning anchor 8. After loading to 100%, let it stand for 8 hours to complete the tensioning.

[0079] Step 7: Top plate reinforcement binding, place a cross-bracing shaped stirrup 7 at one-third of the span at the bottom of the hollow plate structure, place a core mold 21 on the stirrup, lay the top plate reinforcement 3-3 above the core mold 21, and form a reinforcement cage with the vertical reinforcement 3-2 through binding wire.

[0080] Step 8: Concrete pouring. Place end formwork 19 and side formwork 20 at the end and side of the steel cage respectively. The two are connected by bolts to form a whole. Spray sealing foam on the bottom of the end formwork 19 to prevent leakage. Then start pouring concrete. Vibrate with a vibrator while pouring. At the same time, make 5 150mm cubic test blocks for later determination of whether the tensioning conditions are met, that is, the concrete strength reaches 90%.

[0081] Step 9: Release the prestressed CFRP embossed bars (2). When the concrete strength reaches 90%, release begins. The release is divided into four stages: 90%, 60%, 30%, and 0%. The staged release gradually releases the prestress so that the concrete can gradually withstand the increased stress, thereby effectively avoiding local cracking of the concrete or reduction in bearing capacity. After release, the CFRP embossed bars 2 at both ends of the hollow slab are removed.

[0082] Step 10: After the concrete has been cured for 28 days, the mold is removed and the pre-tensioned CFRP reinforced concrete hollow slab is produced.

[0083] The hollow slab structure constructed in the above scheme is combined with a pre-tensioned CFRP reinforced concrete hollow slab structure, a tensioning anchor and a construction method. The prestressed tendons in the structure adopt CFRP embossed tendons. The CFRP embossed tendons can be reliably bonded to the concrete under high prestress without bond slip failure.

[0084] Secondly, the provided tendon tensioning anchor has reliable anchoring, thus avoiding shear failure of the CFRP tendon during tensioning.

[0085] Finally, a complete set of construction methods for pre-stressed CFRP reinforced concrete hollow slabs was formed, providing guidance for the industrialized production of pre-stressed CFRP reinforced concrete structures.

[0086] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A pre-tensioned CFRP reinforced concrete hollow slab, characterized in that: include: CFRP embossed bars, skeleton structure, spiral bars, PVC pipes, pads and concrete, the pads are respectively placed on the lower side of the bottom plate steel bars and the outer side of the vertical steel bars on both sides, the CFRP embossed bars are equidistantly distributed and placed in the skeleton structure and tensioned, the spiral bars are inserted into the prestressed CFRP embossed bars and placed at both ends of the prestressed CFRP embossed bars bonding section, the PVC pipe is inserted into the prestressed CFRP embossed bars and placed at both ends of the prestressed CFRP embossed bars to form a non-bonded section, after the CFRP embossed bars are tensioned, concrete is poured in cooperation with the mold outside the skeleton structure, and after the concrete is formed, the mold is removed to form a pre-tensioned CFRP bar concrete hollow slab structure.

2. The pre-tensioned CFRP reinforced concrete hollow slab according to claim 1, characterized in that: The skeleton structure includes top plate steel bars, vertical steel bars and bottom plate steel bars, wherein the bottom plate steel bars and the top plate steel bars are equidistantly distributed along the length direction of the hollow plate structure, and the vertical steel bars are arranged between the top plate steel bars and the bottom plate steel bars and are connected to the top plate steel bars and the bottom plate steel bars at both ends to form a steel cage.

3. The pre-tensioned CFRP reinforced concrete hollow slab according to claim 1, characterized in that: The surface of the CFRP embossed rib is provided with ribs formed by applying circumferential pressure during pultrusion of the CFRP rib.

4. A tension anchor, characterized in that: The tensioning anchors are arranged at both ends of the CFRP embossed bars in the pre-tensioned CFRP reinforced concrete hollow slab.

5. A tension anchor according to claim 4, characterized in that: The tension anchor comprises an outer membrane sleeve and an inner membrane clip. The inner membrane clip is arranged in the outer membrane sleeve and is integrally sleeved on both ends of the CFRP embossed rib to preliminarily tighten the CFRP embossed rib.

6. A tension anchor according to claim 5, characterized in that: The two ends of the outer membrane sleeve are respectively a tensioning end and a connecting end. The interior of the tensioning end is an inverted cone, and the connecting end is a hollow sleeve with an internal thread.

7. A tension anchor according to claim 5, characterized in that: The inner membrane clip is an inverted cone-shaped three-petal clip, and its length is consistent with the length of the tensioning end of the outer membrane sleeve.

8. A tension anchor according to claim 5, characterized in that: The tensioning anchor is also provided with a pre-tightening tool, which includes an outer diameter adjustment tube, an ejector rod and a hand-lift pump connecting end. The outer diameter adjustment tube cooperates with the outer membrane sleeve, the outer membrane sleeve is inserted into the outer diameter adjustment tube, the ejector rod is placed in the threaded inner hole of the outer membrane sleeve, and then the whole is placed in the cavity of the tightening tool and arranged opposite to the hand-lift pump connecting end. The hand pump is connected through the hand-lift pump connecting end, and the hand pump is operated to push the cylinder piston out to tighten the inner and outer molds.

9. A tension anchor according to claim 1, characterized in that: The connecting end of the outer membrane sleeve is equipped with a tensioning device, which includes a connecting sleeve, a steel strand anchor and a tensioning pedestal. Both ends of the connecting sleeve are threaded, one end is connected to the connecting end of the outer membrane sleeve, and the other end is connected to the steel strand anchor. The tensioning pedestal is provided with an anchoring end and a tensioning end, and the steel strands on both sides are respectively fixed to the anchoring end and the tensioning end of the tensioning pedestal. The tensioning end is equipped with a jack, and the jack at the tensioning end is operated to push out to tension the CFRP embossed ribs. After the tensioning is completed, concrete is poured on the hollow slab structure.

10. A construction process for a pre-tensioned CFRP reinforced concrete hollow slab, characterized in that: The tension anchor according to any one of claims 4 to 9 is arranged at both ends of the CFRP embossed bars according to any one of claims 1 to 3, and the construction of the pre-tensioned CFRP reinforced concrete hollow slab is completed in cooperation with the tensioning equipment. The construction method comprises the following steps: Step 1: The bottom plate steel bars and vertical steel bars are tied and formed by tying wire according to the design drawings and placed on the tensioning pedestal; Step 2: Place the pads on the lower side of the bottom plate reinforcement and on the outer side of the vertical reinforcements on both sides; Step 3: After the spiral ribs and PVC tubes are inserted into the CFRP embossed ribs, the ends of the CFRP embossed ribs are sequentially passed through the outer mold cone holes and the outer cone inner mold clips, and the inner and outer molds are preliminarily tightened manually; Step 4: Sleeve the outer mold into the outer diameter adjustment tube, put the ejector rod into the threaded inner hole of the outer mold, and then put the whole into the cavity of the tightening tool. Operate the hand pump by hand to push the cylinder piston out to tighten the inner and outer molds; Step 5: The CFRP embossed reinforcement tensioning anchor is connected to the steel strand anchor through the connecting sleeve, and the steel strands on both sides are fixed to the anchor end and the tensioning end of the tensioning pedestal respectively; Step 6: Operate the tensioning control device, and the tensioning end jack tensions the CFRP embossed ribs; Step 7: Place a cross-bracing stirrup at one-third of the span at the bottom of the hollow slab structure, place a core mold on the stirrup, lay the top plate steel bars above the core mold, and form a steel cage with the vertical steel bars through binding wires; Step 8: Place the end form and side form at the end and side of the steel cage respectively, connect the two by bolts to form a whole, and then start pouring concrete; Step 9: After the prestressed CFRP embossed ribs are released, the CFRP embossed ribs at both ends of the hollow slab are cut off; Step 10: After the concrete has been cured for 28 days, remove the mold and complete the production of the pre-stressed CFRP reinforced concrete hollow slab.

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