JP3510356B2 - Method for forming terminal fixing part of high strength fiber composite tension material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a terminal fixing portion of a high strength fiber composite tension material.

[0002]

2. Description of the Related Art High-strength fiber-twisted tension materials have excellent properties such as high strength, high elasticity, non-magnetic properties, and excellent corrosion resistance. Therefore, they are reinforcing materials for structures and buildings, such as prestressed concrete and pretensioned materials. -It is becoming widely used as a tension material for post tension concrete. This high-strength fiber composite tension material has strength as high as that of PC steel twisted wire with respect to tensile in the longitudinal direction, but is weak against local shearing force in the diametrical direction and surface scratches. For this reason, when introducing a tension force, the method of fixing the wedge by directly biting the wedge, which is adopted as a normal fixing method for PC steel stranded wire, may cause cutting due to shear fracture or the surface of the tension material. Slippage occurs due to the destruction of the tissue, and high fixation efficiency cannot be obtained. As measures against this, various methods have been proposed in which the fixing portion is processed at the end portion of the high-strength fiber composite tension material so that local concentration of stress does not occur at the time of fixing. As a typical example thereof, Japanese Patent Laid-Open No. 1-24930
As in Japanese Patent No. 4 and Japanese Utility Model Laid-Open No. 3-120598, the end of the tension material is inserted into the socket-type metal fitting, and a thermosetting resin is injected and cured between the outer circumference of the tension material and the socket-type metal fitting to seal the resin. A type with a mold end, and as in Japanese Patent Laid-Open No. 4-2893, insert the end portion of the tension material into a mold and injection-mold the low melting point alloy around the end portion of the tension material to obtain the tension material with the low melting point alloy. A type in which the end portion is inserted into a metal pipe and pressure-bonded is known.

[0003]

However, in the former prior art, it takes a long time to cure the sealing resin, and in order to cure the sealing resin in an environment where vibration, dust and the like are likely to occur, a socket is used. It requires complicated work such as covering the metal mold with a cover and controlling the temperature while holding the high strength fiber composite tension material and the socket metal mold so that they do not move. The latter uses a metal of over 400 ° C., which may adversely affect the fibers of the tendon, and also requires an expensive and large machine such as an injection molding machine, resulting in high cost, and It is not easy to carry in and move to the site, and a dedicated installation space must be secured. For this reason, the prior art has many problems as a fixing part construction method at the site where the tension material is used, and in reality, it must be processed in a factory. However, when applied as a fixing part processing method in a factory, accurate measuring and processing accuracy are required in order to cut the tension material to the length to be used, and sometimes expensive tension material is wasted due to measurement error. In addition, since the tensioned material having the terminal processed is transported to the site, there is a problem in that it is complicated and has a large capacity in terms of packaging and transportation, and the cost is increased. Further, in the prior arts of JP-A-1-249304 and JP-A-4-2893, since the resin or the low melting point alloy is already bonded as a tubular body to the tension material by the time of pressing the sleeve, There is a problem in that the fixing portion can be formed only at the position, and the fixing position cannot be freely adjusted so as to be able to cope with the site specifications and changes.

The present invention was devised in order to solve the above-mentioned problems, and an object of the present invention is to promptly provide a fixing unit having a good fixing efficiency at an optimum desired position in a place where a tension material is used. It is to provide a method that can be easily formed.

[0005]

In order to achieve the above object, the present invention is to insert a high-strength fiber composite tension material into a sleeve or a mold and fill the gap between the outer shell and the tension material with the material to cure it. By changing the conventional idea of creating a fixing part, a high-strength fiber composite tension material was inserted into a steel pipe containing a cylindrical molded soft resin, and a high-strength fiber composite tension material was created by the plastic flow of the soft resin due to the deformation of the steel pipe. It was designed to be integrated,
That is, in fixing the end of the twist type high strength fiber composite tension material that is a composite of high strength and low elongation fiber and thermosetting resin, using a steel pipe in which a cylindrical soft resin layer is previously integrated inside, A high-strength fiber composite tension material is inserted into the through hole of the soft resin layer, and the resin layer is plastically fluidized by compressing the outer circumference of the steel pipe in this state to press-fit and fill the valleys of the high-strength fiber composite tension material. It was done. The soft resin is preferably a thermosetting resin and the durometer hardness test D
Hardness D by mold is 60-75, elastic modulus is 0.8-1.5
A material having a kN / mm ^{2 level} is used.

[0006]

According to the present invention, the high-strength fiber composite tension material is inserted into the cylindrical soft resin layer provided inside the steel pipe, and the steel pipe is compressed from the outer periphery in this state to form the fixing portion. Therefore, it suffices to prepare a steel pipe having a cylindrical soft resin layer in advance, and the high-strength fiber-composite tension material can be easily and immediately constructed by measuring the length with a site measurement. The steel pipe and resin are independent of the high-strength fiber composite tension material until the compression process of the steel pipe, and the relative position can be changed freely, so the fixing position can be adjusted arbitrarily, and therefore it is optimal for the specifications. It is possible to make a fixing unit at any position. In addition, the soft resin plastically flows due to the decrease in the cross-sectional area due to the compression of the steel pipe, and is press-fitted into the spiral troughs of the high-strength fiber composite tension material.The soft resin is consolidated due to the decrease in the cross-sectional area of the steel pipe. The outer peripheral side is constrained by the plastically deformed steel pipe, and the inner diameter side is pressed against the high-strength fiber composite tension material having a large surface area, and a large frictional force is generated. Furthermore, since the high-strength fiber composite tension material has a twisted structure, it has a large pull-out resistance. Therefore, it is possible to obtain excellent fixing performance even though the adhesive method is not used.

The present invention will be described in detail below with reference to the accompanying drawings. In FIG. 1, A is a twist type high-strength fiber composite tension material that is a composite of high-strength and low-elongation fibers and a thermosetting resin, and B is a fixing member. As shown in FIG. 2, the high-strength fiber composite tension material A is configured by twisting a plurality of strand-shaped fiber composite strands 1. Specifically, each fiber composite strand 1 has a strand structure in which a plurality of composite fiber cores 2 are twisted together. The composite fiber core 2 is a fiber yarn in which a large number of ultra-fine long fibers having high strength and low elongation property such as carbon fiber, polyaramid fiber, and silicon carbide fiber are assembled, and thermosetting epoxy resin, unsaturated polyester resin, polyurethane resin, etc. Of the resin matrix impregnated with the resin matrix, molded with a shaping die and the excess resin removed, and then a powder desiccant such as talc is applied to the surface of the resin-impregnated fiber yarn to dry the surface. Each of the fiber composite strands 1 is formed by twisting a plurality of composite fiber cores 2 and wrapping or braiding the outer periphery 3 with synthetic fibers such as nylon and polyester and outer fibers 3 made of high strength and low elongation fibers. Is made. The high-strength fiber composite tension material A is made by twisting the required number of fiber composite strands 1 at a stage where the impregnated matrix resin is uncured, and then heating to cure the matrix resin. The surface area may be increased by winding the required number of the composite strands 1 and winding a tape of plain weave or twill weave of the above-mentioned material on the outer periphery thereof. In this example, the high-strength fiber composite tension material A uses seven fiber composite strands 1 and has a 1 × 7 structure, but is not limited to this, and 1 × 2, 1 × 3, 1 × 1.
9, 1 × 37, etc. are optional.

On the other hand, the fixing member B comprises a steel pipe 5 and a cylindrical soft resin layer 6 inside the steel pipe 5. The steel pipe 5 withstands the pressure from the soft resin 6 at the time of compression, and when it is made of a soft material to some extent, the steel pipe 5 is still deformed according to the shape of the mold and deformed without uneven thickness to generate a uniform internal pressure. It is preferable because it can be performed. Deformation is likely to occur with a hard steel pipe, so the internal pressure also becomes non-uniform and the fixability deteriorates. In terms of material, for example, carbon steel pipe for piping (SGP), carbon steel pipe for pressure piping (STP)
G) or the like is used. The former has a tensile strength of 290kN
The latter has a tensile strength of 370 kN, and the latter is a softer material. As for the dimensions of the steel pipe 5, the thickness is required to be about 2.5 to 5 mm, and the length is required to be at least about 10 times the outer diameter of the high-strength fiber composite tension material A in view of fixing efficiency. However, when the steel pipe is compressed, it stretches and acts to pull the tendon. Therefore, if the length of the steel pipe is too large, the tension member breaks due to the tension generated inside in an extreme case. Therefore, the upper limit of the length dimension is about 25 times the outer diameter of the high strength fiber composite tension material A. For example, the high strength fiber composite tension material A has a 1 × 7 structure,
When the outer diameter is 12.5 mm, the steel pipe has a length of 150 to 300.
mm and an outer diameter of 21 to 30 mm are suitable. Steel pipe 5
May have a smooth inner surface or may have fine grooves.

Next, the soft resin layer 6 is a resin that is well compatible with the steel pipe 5 and the high-strength fiber composite tension material A, and has a characteristic that it easily flows without being cracked or crushed by a compression force, and has the following properties. Thermosetting resins are suitable. 1) Durometer type hardness test D type hardness D (JIS
K7215) is 60 to 75 2) The elastic modulus is about 0.8 to 1.5 kN / mm ^{2 The} hardness D is required to be smaller than the hardness of the tendon.
When it is 75 or more, the fluidity is lowered, the filling and adhesion to the valley of the surface of the tendon are incomplete, and the tendon is damaged during compression, which is unsuitable. When the hardness D is 60 or less, creep causes creeping, which causes delayed fracture so that the tendon material slips out. Next, when the elastic modulus is 1.5 kN / mm ² or more, the internal pressure rises excessively, which causes damage to the tension material. When the elastic modulus is 0.8 kN / mm ² or less, the internal pressure is insufficient and the tension material is fixed. Unsuitable because the load cannot be increased. Other properties of the resin used include a compression strength of 0.
The compression elongation is 05 kN or more and the compression elongation is 5% or more, preferably about 10%. As a specific example of such a resin, any one of an amine resin such as a tertiary amine, a modified aliphatic polyamine, or a polyamide amine as a curing agent for an epoxy resin is used.
Examples include a mixture of two or more kinds, and a polysulfide compound added for imparting fluidity to the cured product. Also, hardness can be maintained by blending filler such as alumina fine powder.

The soft resin layer 6 has a cylindrical shape having a through hole 60 in the center, and the soft resin layer 6 is previously integrated inside the steel pipe 5 as shown in FIG. The method of obtaining the thing of FIG. 3 is arbitrary. That is, a mandrel-shaped core frame is inserted at the center of the steel pipe 5, and in this state, a thermosetting resin (mixture of main agent and curing agent) is filled or poured into the annular gap between the core frame and the steel pipe 5 to form the core frame. You may take the method of removing. As the core frame, one having poor adhesiveness to the thermosetting resin or one that can be eliminated can be used, or a method of rotating so as not to adhere to the thermosetting resin may be adopted. As another method, a method in which a thermosetting resin is filled or poured into the steel pipe 5 and the steel pipe 5 is rotated at a high speed before being hardened to be attached to the inner surface of the steel pipe by a centrifugal force before hardening.
Further, the steel pipe 5 may be filled with a thermosetting resin so as to be filled therewith, and after being hardened as a solid body, a through hole 60 may be formed in the center of the cross section by machining. The fixing member B shown in FIG. 3 is simple because a long element body is formed and cut into a required fixing length at a factory or on site.

The through hole 60 of the soft resin layer 6 may have a circular straight shape or a shape similar to the contour shape of the high strength fiber composite tension material A. The size of the through hole 60 matches the outer diameter of the high strength fiber composite tension material A or is appropriately large. The thickness of the soft resin layer 6 needs to be at least 0.5 mm or more in order to enable the flow during compression. Further, the upper limit is preferably 4 mm in order to transmit the grip force from the steel pipe.

In forming the fixing portion, the end portion a of the high strength fiber composite tension material A is inserted into the through hole 60 of the soft resin layer 6 from the state shown in FIG. Since the soft resin layer 6 and the terminal portion a are independent components that are not bonded to each other, the fixing member B can be arranged at an arbitrary length position of the terminal portion a, and therefore, the fixing portion forming position can be freely adjusted. can do. After the fixing portion forming position is determined in this way, the fixing tool B having the terminal portion a inserted therein is placed in the two split molds 7a and 7b of the cold press machine, and only a compressive force is applied. Good. The shape of the cavity may be circular, but it is polygonal in this example from the viewpoint of workability, that is, the inside can be uniformly restrained by one compression. The pressing pressure needs to be large enough to compress the steel pipe and reduce the cross section of the cylindrical resin by 15 to 30%. If the press pressure is too high, the tension material is damaged by excessive internal pressure, and the tension material is broken at a low load, and the fixing load is apparently reduced. On the contrary, if the compression is too low, a sufficient fixing load cannot be obtained. The optimum range of pressing pressure is generally about 1 to 2.5 kN / mm ² , although it depends on the strength, size, resin properties, etc. of the steel pipe 5 used. As a result, the resin adheres and internal pressure is applied, and the steel pipe-resin-tension material is integrated, so that a fixing member can be formed. If the press machine is operated with the above press pressure, the mold halves 7a, 7
In b, the steel pipe 5 is compressed from the entire circumference and is plastically deformed into a polygonal shape having a reduced cross-sectional area as shown in FIGS. 7 and 8. As the steel pipe 5 is pressed and plastic deformation is started, the soft resin layer 5 in the steel pipe receives a strong compressive force from the entire circumference. Soft resin layer 5
Has a hardness D of 60 to 75 and an elastic modulus of 0.8 to 1.5 kN /
Since it is a soft material such as mm ² , it does not crack and fall apart, and the soft resin portion in the region forming the through hole 60 causes plastic flow, and each fiber composite element that constitutes the terminal portion a. It is press-fitted into each spiral valley 10 between the lines 1 and 1 to completely fill the valley. Then, the soft resin layer 6 is consolidated in the process in which the steel pipe 5 is plastically deformed to a predetermined cross-sectional area, the outer diameter side is constrained by the inner surface 50 of the steel pipe 5, and the inner diameter side has a large surface area end portion a due to the twist structure. It comes into pressure contact with the surface of with a large friction force. Therefore, the terminal portion a, the soft resin layer 6 and the steel pipe 5 are tightly integrated. Further, since the fiber composite strands 1 and 1 have spiral irregularities and the soft resin is press-fitted into the spiral concave portions, a large pullout resistance can be obtained. As a result, the fixing portion C having high fixing efficiency is formed. Although not shown, the fixing portion C is formed on the other end of the high-strength fiber composite tension material A by the same procedure.

To obtain prestressed concrete by the post-tension method using the fixing portion C as described above, the fixing portion C is inserted into the socket 11 as shown in FIGS. 9 and 10, and the sectional shape of the plastically deformed steel pipe is obtained. A plurality of split wedges 12 each having a contact surface having a shape corresponding to are driven between the socket 11 and the fixing portion C, and the socket 11 is supported by the pressure plate 14. Then, similarly fix the fixing part on the other end with a wedge, jack up the socket with a tension fixing jack, and after reaching a predetermined tension, fix a shim plate between the front end of the socket and the pressure plate. Then you can remove the tension bar. In addition, in FIG. 10, 13 is a sheath tube. According to the present invention, as described above, the fixing portion C in which the terminal portion a, the soft resin layer 6 and the steel pipe 5 are tightly integrated is provided, so that the fixing efficiency is high and the outer shell of the fixing portion C is Since the soft resin layer 5 constituted by the steel pipe 5 functions as a cushioning material, even if the compressive force of the wedge acts, the shear fracture of the fiber is prevented and a high tension force can be applied.
Moreover, since the diameter of the steel pipe can be made small because the diameter of the steel pipe is relatively small, the reinforcement density of the tendon can be increased. These make it possible to produce lightweight and thin concrete having excellent corrosion resistance.

[0014]

EXAMPLES Examples of the present invention will be described below. As the composite twist type tension material A, 35 wt% of epoxy resin is added to carbon fiber yarn.
%, Impregnated, talc powder applied and prepreged into multiple strands, and polyester fibers are wound around the outer periphery to make a composite wire, and this composite wire is 1 × 7 with the resin being uncured. An outer diameter of 12.5 mmφ obtained by twisting the structure and heat treatment to cure the epoxy resin was used. The guaranteed breaking load of this composite twist type tension member A is 142 kN, the actual breaking load strength is 161 kN, and the target value of the fixing efficiency is 90% or more. The fixing tool B is made of SGP and S as steel pipes.
Two kinds of materials of TGP were used, and the resin layer had various thicknesses which were integrally molded by filling the inside of a steel pipe with a soft epoxy resin in which a main component was mixed with a modified aliphatic amine and curing it. The press machine was a two-way cold press machine having a hexagonal cavity, and the press pressure was varied.
The obtained fixing portion is fixed with three wedges and a socket having an outer diameter of 65 mm to give a tension force to the composite twist type tension member A,
The fixing efficiency (fixing load / breaking load of tendons × 100) was measured. The results are shown in Table 1. For comparison, Table 1 also shows specifications and fixing test results when a fixing portion is made of a resin having a high hardness and a resin having a high elastic modulus.

[0015]

[Table 1]

As is clear from Table 1, Examples 1 to 4 have good fixing efficiency. This is because the material of the steel pipe, the resin hardness D and the elastic modulus, the resin thickness, and the pressing pressure are appropriate. In Comparative Examples 1 and 2, the material and length of the steel pipe are appropriate, but the resin hardness D is too soft (Comparative Example 1) or too hard (Comparative Example 2), so that the fixing efficiency is low.

[0017]

According to the present invention described above, the steel pipe 5 in which the cylindrical soft resin layer 6 is previously integrated inside is used,
The high-strength fiber composite tension material A is inserted into the through-hole 60 of the soft resin layer 6, and the steel pipe 5 is compressed from the outer periphery in this state to plastically flow the resin layer and the valley of the high-strength fiber composite tension material A. Since the steel pipe 5 and the high-strength fiber composite tension material A are relatively rotated and fitted to each other, there is no need to wait for the resin to harden, and to manage the temperature, etc.
Further, it is not necessary to use a special machine such as an injection molding machine or a heating device, and it is possible to extremely easily and efficiently make a fixing unit having a good fixing efficiency at a use site. Further, there is no need to form a spiral groove in the soft resin layer 6 that matches the pitch of the high-strength fiber composite tension material, and it is not necessary to form a tubular layer for the fixing portion on the outer periphery of the high-strength fiber composite tension material. Since it is possible to measure and cut the product in a straight state while it is aligned with the site, it can be shipped from the factory, transported, etc. easily and with a small capacity, and can be fixed freely until the steel pipe is compressed. Since the position can be changed, the excellent effect that the fixing portion can be provided at an economical and optimum position for the specifications and the tension can be applied can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing a state before starting formation of a terminal fixing portion of a high-strength fiber composite tension material according to the present invention.

FIG. 2 is an enlarged sectional view showing an example of a high-strength fiber composite tension material used in the present invention.

FIG. 3 is a vertical sectional side view showing an example of a fixing member used in the present invention.

FIG. 4 is a vertical sectional side view showing a first stage of the present invention.

FIG. 5 is a vertical sectional side view showing a second stage of the present invention.

FIG. 6 is a vertical cross-sectional front view showing the engagement with the press die in the second stage.

FIG. 7 is a vertical cross-sectional side view of the fixing unit obtained by the present invention.

FIG. 8 is a cross-sectional view taken along line XX of FIG.

FIG. 9 is a perspective view showing a fixing state using the fixing unit according to the present invention.

FIG. 10 is a side sectional view showing a state in which the fixing portion according to the present invention is applied to the production of prestressed concrete.

[Explanation of symbols]

A high strength fiber composite tension material a Terminal B Fixing member 5 steel pipe 6 Soft resin layer 50 through holes C fixing unit

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-7-27630 (JP, A)                 Japanese Patent Laid-Open No. 5-179761 (JP, A)                 Japanese Patent Laid-Open No. 4-203068 (JP, A)

Claims (2)

(57) [Claims] 1. A cylindrical soft resin layer is preliminarily integrated inside in order to obtain a fixing portion in a twist type high strength fiber composite tension material which is a composite of high strength and low elongation fiber and thermosetting resin. Using a steel pipe, a high-strength fiber composite tension material is inserted into the through hole of the soft resin layer, and in this state the steel pipe is compressed from the outer circumference to plastically flow the soft resin layer and the valley of the high-strength fiber composite tension material. A method for forming a terminal fixing portion of a high-strength fiber composite tension material, which comprises press-fitting and filling. 2. The high strength fiber composite tension material according to claim 1, wherein the soft resin layer is a thermosetting resin having a hardness D of 60 to 75 and an elastic modulus of about 0.8 to 1.5 kN / mm ^2. Method for forming terminal fixing part.