JPH07158210A - Frp tendon - Google Patents

Abstract

PURPOSE:To carry out effective unbonding surface treatment to a FRP member. CONSTITUTION:Carbon fiber, araimd fiber and glass fiber which are reinforced with plastics are used as FRP members 12 being the core materials of FRP tendons 10. Various types, namely bar type, twisted wire type and braid type are used as the members 12. The synthetic resin of polyethylene or polytetrafluorethylene which is small in the coefficient of surface friction is applied to the surface of the FRP member 12 as the first layer to form a synthetic resin layer 14. Especially a polytetrafluorethylene tape is small in the coefficient of friction and easy in covering work. The outer surface of the synthetic layer 14 is covered with a plastic sheath 16, and the covered layer 14 is the outermost surface of the FRP tension member 14. The surface of the FRP member is generally nonsmooth, and especially the surface of twisted wire type or braid type FRP member 12 is large in an irregularity, but can be smoothed by the covered synthetic resin layer 14, and a slide is carried out between the synthetic resin layer 14 and the plastic sheath 16 to make unbonding practicable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforced plastic fiber tension material (hereinafter referred to as "FRP tension material"), and particularly to an unbonded surface treatment for use in a prestressed concrete (hereinafter referred to as PC) structure. FR
It relates to P tension material.

[0002]

2. Description of the Related Art The method for constructing a PC structure includes:
A pre-tension method mainly applied to factory products,
There is a post tension method applied to a PC structure cast in situ. The post-tensioning method pre-stresses the PC tension material after placing concrete at the site, and roughly divides it into a structure and puts a sheath in the structure beforehand. A method of injecting grout material such as cement milk between them to integrate them as a structure, and grease on the surface of the tension material,
There is a method of simplifying construction by introducing pre-stress into a PC tension material that has been unbonded with a covering material or the like after placing concrete and omitting grout work.

Conventionally, unbonding treatment has been performed on PC steel materials such as PC steel rods and PC steel strands. In the case of a PC steel rod, the surface is smooth and straight, so a viscous asphalt-based film is applied, and a protective paper or the like is covered on the PC steel bar to improve the slip. In the case of unbonded PC steel rods and unbonded PC steel strands, grease having excellent rust prevention and lubricity is applied to the outer circumference of the steel material and covered with a sheath made of polyethylene or the like.

Further, a double-coated unbonded PC steel material is also known to improve durability against external damage and corrosion (Japanese Patent Laid-Open No. 64-10854).

As described above, the conventional PC tension material is P
Although C steel was used, PC steel still suffers from corrosiveness. Therefore, in recent years, research and development have been carried out using FRP tension materials in which carbon fibers, aramid fibers, glass fibers, etc. are reinforced with plastics instead of PC steel materials.

The FRP material is a material having high strength and light weight and excellent corrosion resistance, but it has a smaller Young's modulus and only a few percent of elongation ability as compared with the conventional PC steel material. In this case, the final proof stress of the member is not crushing of the concrete on the compression side, but there is a risk of causing brittle fracture by rupture of the tendons. In order to impart toughness by converting the member exhibiting such brittle fracture property into crushing of the concrete on the compression side, it is effective to apply the unbond coating to the FRP material. However, at present, no effective unbonded surface treatment method for FRP materials is known.

[0007]

OBJECT OF THE INVENTION It is an object of the present invention to provide a FRP tendon having excellent durability and high practicality.

[0008]

SUMMARY OF THE INVENTION The FRP tension material of the present invention is characterized in that the surface of the FRP material is coated with a synthetic resin and the outermost surface is coated with a plastic sheath. A friction reducing material may be interposed between the synthetic resin layer and the plastic sheath. The surface of the FRP material is smoothed by the synthetic resin layer, and the unbonding can be performed by sliding between the synthetic resin layer and the plastic sheath.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view of the FRP tension material 10, in which the FRP material 12 as the core material is double-coated. In the present invention, as the FRP material 12, carbon fiber,
Use aramid fiber, glass fiber, etc. reinforced with plastic. Further, the FRP material 12 is a rod type,
Either a twisted wire type or a braided type can be applied.

On the surface of the FRP material 12, a synthetic resin layer 14 is formed as a first layer by applying or coating a synthetic resin having a small surface friction coefficient. Examples of the synthetic resin include polyethylene, polyester, and fluororesins such as polytetrafluoroethylene known under the trademark of Teflon. In particular, a tape of polytetrafluoroethylene is preferable as a surface coating because it has a small friction coefficient and the coating operation is easy. Further, in this case, in order to reduce friction with a plastic sheath 16 described later, the tape may be wound in two layers and slid between the tapes to further exert the unbonding effect.

The outer surface of the synthetic resin layer 14 is covered with a plastic sheath 16, and this layer becomes the outermost surface of the FRP tendon 10. The plastic sheath 16 is made of polyethylene, polyester or the like.

The surface of the FRP material is generally not smooth, and in particular, the surface of the twisted wire type and the braided type FRP material 12 has large irregularities, but the coated synthetic resin layer 14 can be used to smooth the surface. The unbonding can be performed by sliding between the resin layer 14 and the plastic sheath 16.

FIG. 2 is a cross-sectional view of the FRP tension member 10 having three covering layers. In FIG. 2, the same layers as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the embodiment shown in FIG. 2, the synthetic resin layer 14 and the plastic sheath 1
6 is different from the above embodiment in that a friction reducing material 18 is interposed between the six. As the friction reducing material 18, grease or other lubricant, asphalt, tar or the like can be used.

The FRP tension member 10 can be manufactured according to the conventional unbonding method for PC steel.
That is, the surface of the FRP material 12 may be sequentially covered with a heat-shrinkable tube from the first layer to be heat-shrinked, extruded and coated with molten plastic, wound with a tape, or coated with grease or tar.

Next, the operation of the FRP tendon 10 will be described. The introduction of prestress as a tendon for PC structures can be done in the same way as conventional unbonded PC steel. Further, the FRP tension material 10 of the present invention
Is a conventional unbonded P as a multi-type tension material.
It can be used in the same way as C steel.

Further, in the case of attaching the grout type fixing tool to the unbonded tension material, which is one of the fixing materials of the tension material currently being developed, a sleeve is put on the outside of the solid FRP material 12 and the sleeve is covered. A grout material is injected between the FRP material 12 and the FRP material 12 to fix the material. At this time, if grease or asphalt is present on the outer peripheral surface of the FRP material 12, FR
The adhesion strength between the P material 12 and the grout material decreases, and the fixing efficiency deteriorates. However, the FRP tendon 10 of the present invention is
Since grease or the like does not directly contact the surface of the RP material 12, it is not necessary to remove the grease or the like even when the grout type fixing device is attached later.

[0018]

EFFECTS OF THE INVENTION The FRP tension material of the present invention reduces the friction loss at the time of introducing prestress by performing the effective unbonding surface treatment on the FRP material having high corrosion resistance, and at the same time, The surface can be protected from external damage.

Further, since the unbonding process is performed without directly contacting the FRP material with a lubricant such as grease, it is not necessary to remove the lubricant, and the fixing device can be mounted very easily. Furthermore, it is also possible to avoid chemical effects that are unclear at present whether grease or the like affects the FRP material.

The FRP tension member of the present invention can be used not only as a tension member by placing it in a concrete member, but also as it is, as an out cable, a lock anchor, an earth anchor or the like.

[Brief description of drawings]

FIG. 1 is a sectional view of an FRP tendon material according to the present invention.

FIG. 2 is a cross-sectional view of another FRP tendon material according to the present invention.

[Explanation of symbols]

 10 FRP tension material 12 FRP material 14 Synthetic resin layer 16 Plastic sheath 18 Friction reducing material

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshio Morii 7-8-1, Higashi Narashino, Narashino-shi, Chiba Suzuki Metal Industry Co., Ltd. (72) Inventor Yoshihiro Abe 7-8-1, Higashi Narashino, Narashino, Chiba Suzuki Metal Industry Co., Ltd. (72) Inventor Osamu Fujiwara 7-8-1, Higashi Narashino, Narashino City, Chiba Prefecture Suzuki Metal Industry Co., Ltd.

Claims (2)

[Claims] 1. The surface of the FRP material is coated with a synthetic resin,
FRP with the outermost surface covered with a plastic sheath
Tension material. 2. The FRP according to claim 1, wherein a friction reducing material is interposed between the synthetic resin layer and the plastic sheath.
Tension material.