Fixing structure

Abstract

To provide a fixing structure for a rod material made of fiber-reinforced plastic, which can exhibit excellent fixing performance.SOLUTION: A fixing structure 1 fixes an FRP rod material 3 in a concrete 2. In the fixing structure 1, a fixing portion 30 for fixing the FRP rod material 3 to the concrete 2 is provided at the tip of the FRP rod material 3, and spiral reinforcement 4 is arranged to surround the general portion adjacent to the fixing portion 30 of the FRP rod material 3 and to restrain the concrete 2 around the general portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fixing structure for a rod material made of fiber-reinforced plastic. [Background technology]

[0002] In recent years, there has been an increasing number of cases where rods made of FRP (fiber reinforced plastic), which are lightweight, strong, and highly durable, are used as concrete reinforcement materials in place of steel bars and other steel materials.

[0003] Patent Document 1 describes a structure for fixing FRP rod material to concrete as a reinforcing material, in which a rod material is made of twisted FRP wires, the wires at the end are unwound to form clusters, and a filler material is filled between the wires to form an expanded diameter section.

[0004] In this anchorage structure, when a tensile force is generated in the rod material, the tensile force of the rod material is borne by the bearing resistance of the concrete at the base of the enlarged diameter section and the adhesion resistance between the surface of the enlarged diameter section and the concrete. Patent Document 1 also describes that by providing spiral reinforcement surrounding the enlarged diameter section, cracking of the concrete around the enlarged diameter section due to the enlarged diameter section sinking in can be prevented, improving the anchorage force. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6442104 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the anchorage structure of Patent Document 1, the concrete at the base of the enlarged diameter section bears a heavy burden, and if a large tensile force acts on the rod material, the concrete at the base of the enlarged diameter section may be destroyed by the bearing pressure. Another problem is that it is difficult to expect an effect on anchorage in the general section where the wires are not unraveled.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a fixing structure for a rod material made of fiber-reinforced plastic, which can exhibit excellent fixing performance. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a fixing structure for fixing a rod material made of fiber-reinforced plastic within a hardening material, characterized in that a fixing portion for fixing the rod material to the hardening material is provided at the tip of the rod material, and a restraining material is arranged to surround a general portion adjacent to the fixing portion of the rod material and restrain the hardening material around the general portion.

[0009] In this invention, an anchorage section is provided at the tip of a fiber-reinforced plastic rod, and a restraining member is placed around the general section of the rod adjacent to the anchorage section to restrain the hardened material around the general section. With this anchorage structure, the tensile force of the rod is borne by the bearing resistance of the concrete at the base of the anchorage section and the bond resistance of the general section of the rod. However, by restraining the hardened material around the general section of the rod with the restraining member, cracking of the hardened material can be prevented, making it easy to ensure bond resistance. Furthermore, because cracking of the hardened material is prevented in the position adjacent to the anchorage section, bearing resistance can also be improved.

[0010] The rod material may be, for example, fiber-reinforced plastic wires twisted together, and the fixing portion may be, for example, the wires unwound and a filler material filled between the wires. Alternatively, the fixing portion may be formed by bending the tip of the rod material. Furthermore, the fixing portion may be formed by attaching a fixing jig to the tip of the rod material. The rod material can be reliably fixed in the hardening material by subjecting the tip of the rod material to the above-mentioned untwisting and diameter expansion process or bending process, or by attaching a fixing jig to the tip of the rod material.

[0011] The restraining material is, for example, a spiral reinforcement. This makes it easy to install a restraining material with specifications that correspond to the adhesion resistance required of the rod material.

[0012] The restraining material may be arranged to surround general portions of the plurality of rod materials. This reduces the number of restraining materials that need to be installed, improving workability during construction. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a fixing structure for a rod material made of fiber-reinforced plastic, which can exhibit excellent fixing performance. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 shows a fixing structure 1. [Figure 2] A diagram showing formwork 5. [Figure 3] FIG. 10 is a diagram showing restraint members 4a and 4b. [Figure 4] An example of spiral muscle placement. [Figure 5] FIG. 1 shows anchoring structures 1a and 1b. [Figure 6] FIG. 1C is a diagram showing the fixing structure 1c. [Figure 7] FIG. 1D shows the fixing structure 1d. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0016] 1 is a diagram showing an anchoring structure 1 according to an embodiment of the present invention. The anchoring structure 1 anchors an FRP rod material 3 into concrete 2, which is a hardening material.

[0017] The FRP rod material 3 is made by twisting together a plurality of wires 31 made of FRP (fiber reinforced plastic) in a spiral shape. The wires 31 are made by bundling a large number of continuous fibers and integrating them with resin, and the diameter and number of the wires are set appropriately. For example, carbon fiber or glass fiber is used as the fiber, and for example, a thermosetting resin such as epoxy resin is used as the resin, but the fiber and resin are not limited to these.

[0018] An anchoring portion 30 is provided at the tip of the FRP rod material 3. The anchoring portion 30 is an expanded diameter portion formed by untwisting the wires 31 of the FRP rod material 3 to form a tuft and filling the spaces between the wires 31 with a filler material 32 (called an untwisting and expanding diameter process). A hardening material such as mortar is used as the filler material 32, but it is not limited to this.

[0019] In this embodiment, the spiral reinforcement 4 is arranged so as to surround the general portion of the FRP rod 3 adjacent to the anchorage portion 30. The general portion is the portion of the FRP rod 3 other than the anchorage portion 30. Concrete 2 is also filled between the general portion of the FRP rod 3 and the spiral reinforcement 4. In this anchorage structure 1, one spiral reinforcement 4 is arranged per FRP rod 3.

[0020] The spiral reinforcement 4 functions as a restraining material that prevents the concrete 2 from cracking by restraining the concrete 2 around the general part of the FRP rod material 3 located inside it.

[0021] When a tensile force T is generated in the FRP rod material 3, the pressure (bearing pressure) applied from the anchorage part 30 to the concrete 2 is supported by the concrete 2 (see symbol A in FIG. 1) on the base side of the anchorage part 30. Hereinafter, this may be referred to as bearing resistance.

[0022] The tensile force T is also supported by the adhesion between the general portion of the FRP rod material 3 and the surrounding concrete 2 (see symbol B in FIG. 1). Hereinafter, this may be referred to as adhesion resistance.

[0023] In the anchorage structure 1 of this embodiment, by arranging the spiral reinforcement 4 so as to surround the general portion of the FRP rod material 3, the restraining effect of the spiral reinforcement 4 prevents cracking of the concrete 2 around the general portion of the FRP rod material 3, ensuring bond resistance. Furthermore, because cracking of the concrete 2 is prevented in positions adjacent to the anchorage portion 30, the bearing resistance can also be improved. As a result, the anchorage effect of the FRP rod material 3 due to the bond resistance and bearing resistance is enhanced.

[0024] In the anchorage structure 1, the tensile force borne by adhesion resistance can be set by adjusting the characteristics of the spiral reinforcement 4. In other words, the material, diameter, spiral spacing, length, etc. of the spiral reinforcement 4 are appropriately set according to the adhesion resistance required of the FRP rod material 3. In a corrosive environment, it is desirable for the spiral reinforcement 4 to be made of FRP, but it may also be made of steel.

[0025] Furthermore, if the gap between the FRP rod material 3 and the spiral reinforcement 4 is too small, the coarse aggregate of the concrete 2 will not be able to penetrate inside the spiral reinforcement 4. For this reason, it is desirable to leave an appropriate gap between the FRP rod material 3 and the spiral reinforcement 4. For example, by referring to the structural details of the Standard Specifications of the Japan Society of Civil Engineers, the gap can be set to at least 4 / 3 of the maximum dimension of the coarse aggregate of the concrete 2. Because the spiral reinforcement 4 is provided in the general part of the FRP rod material 3, which has a smaller diameter than the anchorage part 30, even if the gap is made larger to some extent, problems such as interference with other objects embedded in the concrete 2 (such as rebar) are unlikely to occur.

[0026] On the other hand, if this gap is too large, the confining effect of the spiral reinforcement 4 on the concrete 2 will be reduced. Therefore, the gap between the FRP rod material 3 and the spiral reinforcement 4 is set to an appropriate value, for example, 100 mm or less, taking the confining effect into consideration.

[0027] When constructing the anchorage structure 1, the FRP rod material 3 is untwisted and expanded on-site, and the untwisted and expanded FRP rod material 3 and spiral reinforcement 4 are placed, after which concrete 2 is poured and carefully compacted. The concrete 2 is also filled between the general part of the FRP rod material 3 and the spiral reinforcement 4. The spiral reinforcement 4 may be placed either before or after the untwisting and expansion of the FRP rod material 3.

[0028] As described above, in the anchorage structure 1 of this embodiment, the anchorage section 30 is provided at the tip of the FRP rod 3, and the spiral reinforcement 4 is arranged to surround the general section of the FRP rod 3 adjacent to the anchorage section 30 and restrain the concrete 2 around the general section. In this anchorage structure 1, the tensile force of the FRP rod 3 is borne by the bearing resistance of the concrete 2 at the base of the anchorage section 30 and the bond resistance of the general section of the FRP rod 3, but by restraining the concrete 2 around the general section of the FRP rod 3 with the spiral reinforcement 4, cracking of the concrete 2 can be prevented and bond resistance can be easily ensured. Furthermore, because cracking of the concrete 2 is prevented adjacent to the anchorage section 30, the bearing resistance can also be improved.

[0029] The anchoring portion 30 is formed by subjecting the tip of the FRP rod material 3 to the untwisting and diameter expansion process described above, thereby enabling the FRP rod material 3 to be reliably fixed in the concrete 2 .

[0030] Furthermore, in this embodiment, by using the spiral reinforcement 4 as a restraining material for the concrete 2, a restraining material with specifications according to the adhesion resistance required for the FRP rod material 3 can be easily constructed.

[0031] However, the present invention is not limited to the above-described embodiment. For example, as shown in FIG. 2 , the construction method of the anchorage structure 1 may be different. After arranging the FRP rods 3 and the spiral reinforcement 4, a cylindrical formwork 5 may be installed around the spiral reinforcement 4, and the formwork 5 may be filled with the hardening material 20. The hardening material 20 may be, for example, mortar, but it may also be concrete. After the hardening material 20 hardens, the formwork 5 is removed, and concrete 2 is poured to complete the anchorage structure. This reliably prevents improper filling of the hardening material 20 around the general portions of the FRP rods 3. It is also desirable to form irregularities on the surface of the hardening material 20 to ensure the integrity of the hardening material 20 and the concrete 2. The irregularities can be formed, for example, by providing protrusions on the inside of the formwork 5, but the method of formation is not limited thereto.

[0032] Furthermore, the restraining material for the concrete 2 is not limited to the spiral reinforcement 4. For example, the restraining material 4a in Fig. 3(a) is a cylindrical member with circumferential slits 41, and the restraining material 4b in Fig. 3(b) is a plurality of annular members 42 lined up and connected by rod-shaped members 43. The same effect as the spiral reinforcement 4 can be obtained by arranging these restraining materials 4a and 4b so that they surround the general portion of the FRP rod material 3.

[0033] Furthermore, as shown in the anchorage structure 1' in Figure 4(a), one spiral reinforcing bar 4 may be placed for multiple FRP rod materials 3. The spiral reinforcing bar 4 is placed so as to surround the general parts of the multiple FRP rod materials 3, and the dimensions of the spiral reinforcing bar 4 are adjusted so that the amount of reinforcement is approximately the same as when spiral reinforcing bar 4 is placed for each of the multiple FRP rod materials 3. This reduces the number of spiral reinforcing bars 4 to be installed, improving workability during construction.

[0034] Furthermore, when spiral reinforcement 4 is arranged for each of multiple FRP rods 3, adjacent spiral reinforcement 4 may be partially overlapped as shown in Figure 4(b). This reduces the space required to secure the FRP rods 3.

[0035] Furthermore, the FRP rod material 3 of this embodiment has unevenness on its surface caused by twisting together multiple wires 31, but in order to generate greater adhesion resistance, the surface of the wires 31 themselves may have annular protrusions like deformed steel bars.

[0036] Furthermore, the anchoring portion 30 of the FRP rod material 3 is not limited to the above. For example, as shown in anchoring structures 1a and 1b in Figures 5(a) and 5(b), the tip of the FRP rod material 3 may be bent in advance at a factory or the like to form anchoring portions 30a and 30b. This also ensures that the FRP rod material 3 is securely fixed in the concrete 2, and makes it easy to form anchoring portions 30a and 30b. In the example of Figure 5(a), the anchoring portion 30a is an L-shaped bent portion, and in the example of Figure 5(b), the anchoring portion 30b is a U-shaped bent portion. Straight sections of an appropriate length are provided at these bent portions to prevent them from sliding out of the concrete 2.

[0037] As shown in the anchorage structure 1c in Figure 6, an anchoring jig 35 may be attached to the tip of the FRP rod 3 to form an anchorage portion 30c. This also allows the FRP rod 3 to be reliably fixed in the concrete 2, and further eliminates the need to process the FRP rod 3 itself. The anchoring jig 35 is a cylindrical body made of, for example, steel or FRP, and the tip of the FRP rod 3 is inserted into the interior of the body and filled with grout 36 to form the anchorage portion 30d. A bearing plate 351 is provided at the end of the anchoring jig 35 on the spiral reinforcement 4 side to generate bearing resistance in a wide area of the concrete 2. The bearing plate 351 is positioned so as to protrude outward from the anchoring jig 35.

[0038] In these anchorage structures 1a, 1b, and 1c, when a tensile force is generated in the FRP rod material 3, the pressure from the anchorage parts 30a, 30b, and 30c is supported by the concrete 2 (see symbol A in each figure) at the base of the anchorage parts 30a, 30b, and 30c, and the tensile force of the FRP rod material 3 is borne by this bearing resistance and the bond resistance of the concrete 2 (see symbol B in each figure) around the general part of the FRP rod material 3. Also, as described above, the bond resistance is ensured by the restraint effect of the spiral reinforcement 4 on the concrete 2, and the bearing resistance is also improved. Note that the FRP rod material 3 used in the anchorage structures 1a, 1b, and 1c is not limited to being made of multiple strands 31 twisted together, but may be a single wire.

[0039] 7, the anchoring portion 30d of the FRP rod 3 may be formed by subjecting the tip of the FRP rod 3 to the untwisting and diameter expansion process and then bending it into an L shape, so that the FRP rod 3 is securely anchored to the concrete 2. In this anchoring structure 1d as well, when a tensile force is generated in the FRP rod 3, the pressure from the anchoring portion 30d is supported by the concrete 2 (see symbol A in FIG. 7) on the base side of the anchoring portion 30d, and the tensile force of the FRP rod 3 is borne by this bearing resistance and the adhesion resistance of the concrete 2 (see symbol B in FIG. 7) around the general portion of the FRP rod 3.

[0040] 7, the tip of the FRP rod material 3 is bent into an L shape, but it can also be bent into a U shape. Also, instead of untwisting and expanding the diameter, a fixing jig 35 may be attached.

[0041] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas disclosed in this application, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0042] 1, 1', 1a, 1b, 1c, 1d: Anchoring structure 2: Concrete 3: FRP rod material 4: Spiral muscles 4a, 4b: Restraint material 5: Formwork 20: Hardening material 30, 30a, 30b, 30c, 30d: fixing section 31: Wire 32: Filling material 35: Fixing jig 36: Grout material

Claims

1. A fixing structure for fixing a rod material made of fiber reinforced plastic in a hardening material, a fixing portion for fixing the rod material to a hardening material is provided at a tip portion of the rod material; An anchoring structure characterized in that a restraining material is arranged to surround a general portion adjacent to the anchoring portion of the rod material, for restraining the hardening material around the general portion.

2. The rod material is made by twisting together wires made of fiber-reinforced plastic, 2. The anchoring structure according to claim 1, wherein the anchoring portion is formed by unwinding the wires and filling the spaces between the wires with a filler material.

3. 2. The fixing structure according to claim 1, wherein the fixing portion is formed by bending a tip end of the rod material.

4. 2. The fixing structure according to claim 1, wherein the fixing portion is a fixing jig attached to the tip of the rod material.

5. 2. The anchoring structure according to claim 1, wherein the restraining material is a spiral reinforcement.

6. 2. The anchoring structure according to claim 1, wherein the restraining member is disposed so as to surround general portions of the plurality of rod members.

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