JPH0796838B2 - FRP tension material tension fixing method in prestressed concrete structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension fixing method for a FRP tension material in a PC structure using a fiber reinforced plastic (hereinafter referred to as FRP) as a prestressed concrete (hereinafter referred to as PC) tension material.

[0002]

2. Description of the Related Art Conventionally, a PC structure using an FRP wire as a PC tension material has been proposed for the purpose of solving the problem of corrosion resistance. FRP in this kind of PC structure
To fix the end portion of the tension member, conventionally, as shown in FIG. 7, the end portion of the FRP tension member 1 is inserted into a cylindrical anchor head 2 having an external thread engraved on the outer periphery thereof, and the FRP tension member 1 is wedged into the anchor head 2 to form the FRP. After the tension member 1 is fixed and the anchor head 2 is pulled by a jack to give a tension force, the nut 3 screwed into the anchor head 2 is moved to contact the bearing plate 5 at the end of the concrete structure 4. It was common that they were brought into contact with each other and supported, and these were buried with the buried concrete 6.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Although all the end fixing devices of the tendons are made of steel, the corrosion resistance of FRP for the PC tendons and the corrosion resistance of the fixing devices when non-magnetic material is used. It is preferable to use a magnetic and non-magnetic material.

For this reason, it is possible to mold the conventional fixing device with a corrosion resistant, non- (or low) magnetic material such as high manganese steel or ceramics, but it is technically difficult to manufacture and expensive. Therefore, there has been a problem that it has not been put to practical use yet, and accordingly, the corrosion resistance and non-magnetization of the entire PC structure cannot be achieved.

In view of the above conventional problems, the present invention has been made for the purpose of attaining complete corrosion resistance and non-magnetization of a PC structure using an FRP tension material.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems and achieve the intended purpose, the gist of the present invention is to provide at least a tension side end portion of a sheath embedded in a concrete structure. A taper sheath whose outer end side is widened is provided in advance, and an end portion of the FRP tension material inserted into the sheath is projected through the taper sheath to simultaneously or simultaneously with concrete pouring of the concrete structure. At a different timing before and after installation, the taper sheath is filled with a filler having adhesiveness to FRP, and after the strength of the filler and the structure concrete is developed, the end of the FRP tension member is pulled to obtain tension. A force is applied to make it adhere, and the filler is refilled in the gap between the solidified filler pulled out from the inside of the tapered sheath by the tension and the inner surface of the tapered sheath,
The tension fixing method of the FRP tension material in the prestressed concrete structure is characterized in that the assumed adhesion is solved after the strength of the refilled filler material is developed.

[0007]

According to the method of the present invention, by filling and solidifying the filler in the taper sheath through which the FRP tension material is passed, a tapered block integrated with the FRP tension material in the taper sheath is formed. . When the protruding end of the FRP tension material is pulled after the desired strength of this block is developed, the tapered block is pulled out from the inside of the tapered sheath according to the elongation of the FRP, and a gap is created between the inner surface of the sheath and the block and the tension is increased. Is done. By filling the filler in the gap formed in this way and solidifying it, the block and the block made of the previous filler cannot return to the taper sheath, and by solving the assumed FRP adhesion, The FRP tension material is fixed by the adhesive force between the block and the filling material filled later, and the tension state is maintained.

[0008]

EXAMPLE An example of the present invention will be described with reference to FIGS.

1 (A) to 1 (F) show steps of the method of the present invention. First, as shown in FIG. 1 (A), a sheath 12 for inserting a tendon is inserted in a mold 11. Install. A diameter-expanding sheath 13 is connected to this sheath 12 on one tension member fixed end side, and a taper sheath 14 whose outer side is expanded is connected to the other tension end side. These sheaths 12, 1
The FRP tension material 15 is inserted into the parts 3 and 14.

The expanded sheath 13 and the tapered sheath 1
Partitions 16 and 16 are provided on the boundary of the sheath 4 with the sheath 12, respectively. As shown in FIG. 2, the expanding sheath 13 is provided with filler pouring and discharging holes 17a and 17b, and the taper sheath 14 is provided with the same. As shown in FIG. 3, a window 18 for filling the filling material is formed and is closed by a lid 19.

After arranging the sheaths 12, 13, and 14 in the mold 11, as shown in FIGS.
Concrete 20 is poured into the inside of 1. At the same time, the taper sheath 14 is filled with a high-strength filling material 21 having high viscosity, and the window 18 is closed by the lid 19. On the other hand, the expanded sheath 1
The inside of 3 is filled with a normal filler 22 having high fluidity.

Next, as shown in FIG. 1D, the filler 2
After waiting for the strength of the concrete 1, 22 and the concrete 20 to reach the desired strength, the form 11 is removed, and the reaction force receiving base 23 is set on the concrete end face of the taper sheath 14 side, and the center hole jack 24 is supported by this to support the FRP. The tip of the tension member 15 is pulled to make it tense.

At this time, since the other end of the FRP tension member 15 is fixed in the expanding sheath 13 by the adhesive force of the filler 22, the prestress of the concrete 20 is introduced. At the same time, the FRP tension material 15 expands, but the solidified filler material 21 in the taper sheath 14 becomes FR.
Since it is firmly fixed to the P-tension material 15, FRP
As the tension member 15 extends, the tension member 15 is pulled out from the inside of the taper sheath 14, and the inner surface of the taper sheath 14 and the solidified filler 2
A gap 26 is formed between the two.

After the FRP is strained in this way, FIG.
As shown in (e), the end portion of the FRP tension member 15 is fixed to the reaction force receiving base 23 by using the assumed attachment 25, and the jack 24 is removed. In parallel with this, taper sheath 1
2 between the inner surface of 4 and the solidified filler 21 that has been pulled out
6 is filled with normal filler 22 having high fluidity, and the same filler 22 is injected into the sheath.

After that, the filler 2 in the taper sheath 14
After waiting for the strength of 2 to appear, the hypothetical fitting 25 is removed. As a result, the tensile force of the FRP tension member 15 is supported by the solidified fillers 21 and 22 in the taper sheath 14.

Then, as shown in FIG. 1F, the reaction force receiving base 23 is removed, and the taper-shaped solidified filler 21 and the FRP tension member 15 protruding from the concrete end surface are cut off from the protruding portion 21a from the concrete end surface. To do.

The high-strength filler 21 is, for example, a mixture of Portland cement with an expanding material, silica and silica sand, or a mixture of Portland cement with an expanding material and a thickening agent.

As an example, as shown in FIG. 4, the hypothetical fastener 25 includes an anchor head 30, a fixing wedge 31, and a retainer 3.
2, consisting of a lock nut 33, the FRP tension material 15 is passed through the taper hole 34 of the anchor head 30, the fixing wedge 31 of a half-cylindrical shape is inserted into the taper hole 34, and the retainer 32 is retained by the bolt 35. The FRP tension member 15 is fixed by pushing 32 in the press-fitting direction of the wedge, and is supported on the reaction force receiving base 23 via the lock nut 33 on the outer circumference of the anchor head 30.

In the above-mentioned embodiment, the filling material 21 is filled into the tapered sheath 14 at the same time when the concrete 20 is poured, but the filling material 21 is filled even before the concrete 20 is poured. Well, it may be after placement. Furthermore, as shown in FIG. 5 (a), the same taper sheath 14a as the taper sheath 14 to be embedded in the concrete 20 is used outside the mold 11, and after passing the FRP tension material 15 through this, a high strength filling material is used. 21 is filled and the end block 21a is formed. After that, as shown in FIG. 5B, the FRP tension material 15 is inserted into the sheaths 12, 13 and 14, and the other end side is expanded diameter sheath 13 It may be inserted into the inside and fixed by the filler 22, and thereafter, the tension may be fixed as in the case of FIG.

Further, in the above-mentioned embodiment, it is explained that one FRP tension member 15 is used, but in many cases, in reality, a plurality of FRP tension members 15, 1 are used as shown in FIG.
Use 5 …… for the same part. In FIG. 6, the same parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

[0021]

EFFECTS OF THE INVENTION The tension fixing method for FRP tension material of the present invention described above has the following effects. (1) By using FRP as the tension material and fixing it by this method, it becomes possible to construct a completely corrosion-resistant and non-magnetic PC structure. (2) Corrosion resistance such as high manganese steel and ceramics, which is extremely economical compared with the case of using an expensive fixing tool made of a non- (low) magnetic material. (3) Since the grout for attaching the tension material can be performed before the concrete is poured, the filling can be performed with high reliability while directly confirming it by a method easy to fill. Therefore, it is possible to reliably attach and fix. (4) Since it is easy to fill grout, it is not always necessary to use grout having good fluidity. Therefore, it is possible to use a material having a higher adhesion strength, for example, various types of grout or mortar which are hardened. (5) By using a filler with high adhesion strength,
The length of the tapered sheath can be shortened. Due to this shortening, the filling becomes more reliable and at the same time the construction becomes easier. (6) Since the grout of the gap generated in the tapered sheath after the tension is able to withstand the bearing stress mainly due to the fixing force, the filler can be cured for a short time, and the PC member can be used immediately.

[Brief description of drawings]

1 (a) to 1 (f) are cross-sectional views schematically showing each step of one embodiment of the method of the present invention.

FIG. 2 is a perspective view of the expanding sheath.

FIG. 3 is a perspective view of a tapered sheath used in the above-mentioned embodiment.

FIG. 4 is a sectional view of the hypothetical garment.

FIG. 5 is a cross-sectional view showing a more specific example of a PC structure manufactured by the method of the present invention.

6A to 6B are cross-sectional views showing steps of another embodiment of the method of the present invention.

FIG. 7 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 11 Formwork 12 Sheath 13 Expanding sheath 14 Tapered sheath 15 FRP tension material 16 Partition 17, 17b Filling material pouring hole 18 Window 19 Cover 20 Concrete 21, 22 Filling material 23 Reaction force receiving stand 24 Center hole jack 25 Assumption fitting 26 Gap 30 Anchor Head 31 Fixing Wedge 32 Retainer 33 Lock Nut 34 Tapered Hole 35 Bolt

Claims (1)

[Claims] 1. A taper sheath whose outer end side is widened is provided at least on the tension side end of a sheath embedded in a concrete structure, and the end of the FRP tension material inserted into the sheath is tapered. Project through the sheath,
After the filler having adhesiveness to FRP is filled in the taper sheath at the same time as the concrete pouring of the concrete structure or at another timing before and after pouring, the strength of the filler and the structural concrete is developed. The end portion of the FRP tension material is pulled, and a tension force is applied to make it adhere, and the tension refills the filler between the solidified filler material pulled out from the inside of the taper sheath and the inner surface of the taper sheath. A tension fixing method for an FRP tension material in a prestressed concrete structure, which is characterized in that the hypothetical adhesion is released after the strength of the refilled filler material is developed.