JP2734930B2 - Manufacturing method of prestressed concrete members - 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 of manufacturing a prestressed concrete member by a post-tension method using an electrically-curable rope as a tendon.

[0002]

2. Description of the Related Art Manufacturing methods of prestressed concrete members are roughly classified into a pretension system and a post-tension system. In the post-tension method, concrete is poured around the tension member with a sheath interposed between the tension member and the concrete so that the unstrained tension member does not adhere to the concrete. In general, a grout material is injected under tension to integrate the tendon and the sheath, and the end of the tendon is fixed to concrete.

[0003]

SUMMARY OF THE INVENTION The present invention eliminates the complicated work of using a sheath, injecting a grout material, and fixing an end portion of a tendon material to concrete by a fixing body, while using a post-tension system, and efficiently uses it. It is intended to produce a prestressed concrete member.

[0004]

SUMMARY OF THE INVENTION According to the present invention, concrete is poured into a formwork on which an electrically-curable rope is arranged, and after the concrete is hardened, the electrically-curable rope is tensioned. This is a method for manufacturing a prestressed concrete member, characterized in that it is energized and cured, and then the tension is released.

The current-curing rope used in the present invention is a composite material that has recently attracted attention as a reinforcing material, and is formed by impregnating a carbon fiber bundle with a thermosetting resin (a typical resin is an epoxy resin). It is twisted to size. The electrically curable rope is mainly placed in an uncured state,
By passing electricity through the rope, the heat generated in the rope is used to cure the rope itself and to exert its performance as a reinforcing material.

According to the present invention, during the examination of the properties of such an electrically-curable rope, the uncured electrically-curable rope hardly adheres to concrete, but the rope hardened by energizing the electrically-curable rope under tension is used. It is based on the discovery of the fact that it has a high adhesion to concrete, and is an improvement over the conventional method by utilizing the properties of this electrically-curable rope as a tendon for prestressed concrete members.

[0007] The present invention applies equally well to factory-manufactured prestressed concrete members and on-site prestressed concrete members.

The present invention has the advantages of the post-tension system as compared with the pre-tension system. (1) The construction on site is easy. (2) The suspension type tension member can be arranged.
Compared to the pretensioning method, the post-tensioning method maintains the point that the time from the introduction of tension to the tendon material to the completion of the introduction of prestressing force to the member is short, and there is no need to maintain tension for a long time. Disadvantage of tension method (1)
This eliminates the need for a sheath, (2) requires a fixing body, and (3) requires grout material injection, and can be said to be a new post-tension system.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual view showing a state in which concrete cast around a non-tensioned, uncured state of an electrically-curable rope has hardened, in which (a) is a cross-sectional view and (b) is a longitudinal cross-section. FIG.

FIGS. 2A and 2B are conceptual diagrams showing a state in which the electrically-curable rope in the hardened concrete is tensioned. FIG. 2A is a cross-sectional view, and FIG.

The thermosetting resin is filled between the single fibers of the carbon fiber bundle in the non-tensioned electrically-curable rope 1, and the adhesion between the electrically-curable rope 1 and the concrete 2 is extremely small. When the electrically-curable rope 1 is tensioned, tension acts on the single fibers of the carbon fiber bundle, the distance between the single fibers decreases, and the thermosetting resin 3 contained therebetween is squeezed out and the electrically-curable rope 3 is removed. 1 covers the surface. When electricity is supplied to the electrically-curable rope 1 in this state, the thermosetting resin 3
At the same time as the carbon fiber bundle is hardened by the curing of the thermosetting resin 3 on the surface of the electrically-curable rope 1, the contact surface between the electrically-curable rope 1 and the concrete 2 is firmly bonded.

FIGS. 3A and 3B are vertical sectional views showing the construction sequence of an example in which the present invention is applied to a beam member constructed on site, where FIG. 3A shows a state before concrete is cast and FIG. (C) shows a state in which the tensioned current-cure rope is energized and cured.

(1) The column formwork 7 and the beam formwork 6 are manufactured.
The beam form 6 is supported by the shoring 8.

After reinforcing bars (not shown) are arranged in the column formwork 7 and the beam formwork 6, the current-curable rope 1 is placed in the beam formwork 6.
Are arranged in a suspended manner. (FIG. 3A) (2) Concrete is poured into the column formwork 7 and the beam formwork 6, and after the concrete is hardened, the form dam plate is removed. Next, tension is introduced into the electrically-curable rope 1 using the hydraulic jack 9. (FIG. 3 (b)) (3) The tensioned current-curable rope 1 is energized using the current-applying device 11 to generate heat, and the current-curable rope 1 is cured to obtain the carbon fiber reinforced plastic 10. At the time of curing, the carbon fiber reinforced plastic 10 firmly adheres to the beam concrete 5. Finally, the tension of the hydraulic jack 9 is released.
(FIG. 3 (c)) When the current is applied to the electrically-curable rope 1 to cure it, the temperature of the electrically-curable rope 1 rises to 120 to 170 ° C., but there is no adverse effect on the beam concrete 5. Has been confirmed by an adhesion property test with concrete.

[0016]

The advantages of the post-tension method compared to the pre-tension method are as follows: (1) Easy construction on site; (2) Arrangement of suspension type tension members is possible. (3) Tension to tension members. It is a disadvantage of the post-tension method compared to the pre-tension method, while maintaining that the time from the introduction to the completion of the introduction of the pre-stress force to the member is short and it is not necessary to maintain the tension for a long time. (1) A sheath is required. (2) A fixing body is required. (3) A grout material is required to be injected. Thus, a prestressed concrete member can be manufactured efficiently.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram showing a state in which a non-tensioned electrically-curable rope is buried in hardened concrete, where (a) is a transverse sectional view and (b) is a longitudinal sectional view.

FIGS. 2A and 2B are conceptual views showing a state in which a tension-carrying curable rope is buried in hardened concrete; FIG. 2A is a cross-sectional view, and FIG.

FIGS. 3A and 3B are vertical sectional views showing a construction sequence of an example in which the present invention is applied to a beam member constructed on site; FIG. 3A is a state before concrete is poured, and FIG. ,
(C) shows a state in which the energized curable rope in a tensioned state is energized and cured.

[Explanation of symbols] 1..Electrification-curable rope, 2..Concrete, 3 ..
Thermosetting resin, 4 ... column concrete, 5 ... beam concrete, 6 ... beam formwork, 7 ... column formwork, 8 ... support,
9 ・ ・ Hydraulic jack 、 10 ・ ・ Carbon fiber reinforced plastic 、 11 ・ ・ Electrification device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Akiyama 2-9-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd. (72) Inventor Kazumasa Okumura 2--19, Tobita-Shi, Chofu-shi, Tokyo No. 1 Kashima Construction Co., Ltd. Technical Research Institute (56) References JP-A-52-82921 (JP, A)

Claims (1)

(57) [Claims] An electric curable rope (hereinafter, simply referred to as an “electrically curable rope”) in which a yarn obtained by impregnating a carbon fiber bundle with a thermosetting resin is twisted into a desired size is disposed in a formwork. After placing concrete and hardening the concrete,
A method of manufacturing a prestressed concrete member, comprising: tensioning an electrically-curable rope, applying current to the electrically-curable rope under tension to cure the rope, and then releasing the tension.