JPH047444A - Method for fixing frp tendon - Google Patents

Abstract

PURPOSE:To enhance fixing strength by introducing post tension into an FRP tendon to preliminarily provide depressed parts to a concrete material to be reinforced at the positions of the end parts of the FRP tendon so as to open to the outside. CONSTITUTION:Tapered cylindrical depressed parts 3, 3 are provided to a concrete material 1 so as to open to the outside. Next, the bundle of tendons 4 each composed of an FRP rod is inserted through a sheath 2 and reinforcing rods 5 are arranged around the tendons 4 drawn out into the depressed part 3 and grout 6 is injected in the depressed part 3 to form anchor parts 7. Subsequently, the other ends of the tendons 4 are drawn out of the depressed part 3 to be grasped by wedge-shaped cones 8, 8 and a fixing jig 9 is fitted to the cones 8, 8 to apply tension of desired force to the tendons 4. A fixing plate 11 is interposed and reinforcing rods 5 are arranged around the tendons 4 and the depressed part 3 is filled with the grout 6 to form an anchor part 7. By this method, fixing strength can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for fixing the ends of FRP (fiber-reinforced synthetic resin) tendons when reinforcing concrete material by introducing post-tension into the tendons.

[Problem to be solved by the invention]

FRP materials made of aromatic polyamide fibers (aramid fibers), carbon fibers, glass fibers, etc. as reinforcement materials and epoxy resins, unsaturated polyester resins, etc. as base materials have high tensile strength and tensile modulus, and are resistant to corrosive environments. Due to its excellent durability, it is attracting attention for its use as a reinforcing material for concrete, especially as a tension material.

However, in order to use tension materials such as FRP rods, the ends must be fixed, but unlike steel materials, fixing devices cannot be attached by means such as screwing. For this purpose, conventionally, for example, the fixing tool was attached by sandwiching and gripping the FRP tension material between two wedge-shaped cones inserted into a cylindrical fixing tool having a truncated cone-shaped space. Alternatively, the FRP tension material is inserted into a cylindrical fixing device, and the fixing device is filled with a synthetic resin or the like and fixed, thereby attaching the fixing device. However, the means of clamping and gripping between wedge-shaped cones has a low efficiency with respect to the strength of the tendon, and the means of fixing with synthetic resin has poor reliability in the long term.

[Means to solve the problem]

This invention has been made with attention to the above-mentioned problems, and the gist thereof is to introduce post-tension into the FRP tendon and to open it in advance on the outside at the end position of the FRP tendon of the concrete material to be reinforced. A recess is provided, the other end of the FRP tension material is penetrated through the concrete material and one end is fixed to the concrete material, and the other end is pulled out from the recess to introduce tension, and then the grout is filled and fixed in the recess. A method for fixing FRP tension material is provided.

〔Example〕

Figure 1 shows concrete material 1 that is to be reinforced by introducing post-tension into FRP tension material to form a beam.
A sheath 2 through which the tendon is inserted in the longitudinal direction is embedded, and tapered cylindrical recesses 3, 3 communicating with the sheath 2 and open to the outside are bored at both ends thereof.

Inside the sheath 2 of this concrete material 1, as shown in Fig. 2,
F with aramid fiber as reinforcement material and epoxy resin as base material
A bundle of tension material 4 of the RP rod is inserted and set, and one end (on the right side in the drawing) is used as a fixed end and is first fixed. That is,
After arranging reinforcement reinforcing bars or FRP iron reinforcing bars 5 around the tension material 4, which is a drawer, in the recessed part 3, the recessed part 3 is
It is filled with grout 6 to form an anchor portion 7 and to secure one end of the tendon.

After the grout 6 has hardened, as shown in FIG.
Attach the fixing tool 9 by gripping it between the two. The tension material 4 is pulled through this fixing device 9 with a jack or a traction device, and
Give the desired force tension. In this state, a fixing plate 11 is inserted between the tensioning frame 10 to which the fixing device 9 is attached and the concrete material l, the tensioning material 4 is temporarily fixed, and reinforcing bars 5 are placed around the tensioning material 4 in the concave portion 3. After placing reinforcement, grout 6
is filled to form the anchor part 7. As the grout hardens, the other end of the tensioned tension material 4 is fixed and fixed, so the fixing tool 9 is removed and the excess length of the tension material 4 is cut.

Finally, grout 6 is also injected into the sheath 2. Although this grout is effective in protecting the tendons 4 within the sheath 2, it is not necessary.

In the above embodiment, reinforcing bars 5 such as reinforcing bars or FRP rods are placed inside the concave portion 3 to increase the consolidation force of the grout 6 and improve the strength of a portion of the anchor. The anchor portion 7 may be formed by filling the grout 6 with a steel casing 13 having a shape that can be fitted into the recess 3 and having a through hole 12 communicating with the sheath 2.

The FRP tension material referred to in this invention is FRP reinforced with carbon fiber, aromatic polyamide fiber, glass fiber, etc.
The shape is a round bar, irregularly shaped bar, band shape, strand shape, etc., and one or more pieces are used in a row.

The grout referred to in this invention includes cement paste, cement mortar, synthetic resin paste (e.g., epoxy resin paste composition), resin mortar mixed with synthetic resin, etc., and depends on the type and shape of F R and P tendons, or the type of concrete material. Select according to the purpose of use, etc.

The depth and volume of the recess vary depending on conditions such as the tensile force acting on the tension material, the thickness of the tension material, and the number of tension materials. The anchoring strength of the tension material can be increased in proportion to the depth.

[Action and effect of the invention]

This method of fixing the FRP tendon can fix the end of the post-tensioned tendon by a simple method of filling a recess drilled in the concrete material with grout to form an anchor part. By selecting and using the depth and volume of the recessed portion, or the type and composition of the grout, sufficient fixing strength and long-term durability can be imparted.

[Brief explanation of the drawing]

Figures 1.2 and 3.4 are cross-sectional views showing the method of fixing FRP tendons for concrete materials in the order of steps in the example, and Figure 5.
The figure is a partial sectional view showing another embodiment of a part of the anchor. ■... Concrete material, 2... Sheath, 3... Concave portion, 4... FRP rod tension material, butt... Reinforcement bar,
6... Grout, 7... Part of the anchor, butt... Tree-shaped cone, 9... Anchor, 10... Tension frame, 11...
Fixed plate, 12... Through hole, 13... Casing.

Claims (1)

[Claims] (1) Post-tensioning is introduced into the FRP tendon to provide a recess that opens to the outside in advance at the end position of the FRP tendon of the concrete material to be reinforced, penetrates the inside of the concrete material, and fixes one end to the concrete material. After pulling out the other end of the FRP tension material from the recess and introducing tension,
A method for fixing FRP tension material, characterized by filling and fixing grout in the recessed part.