JPH11100944A - End fixing structure of prestressed steel material in prestressed concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a stress distribution state due to tension force of PC steel material acting on a concrete structure in the neighborhood of a fixing plate by disposing a plurality of bearing plates of a shape in which the flange of a curved surface different in curvature or a flat plate is provided on the edge end part in a bowl type or a reverse bowl type in the form of joined kites. SOLUTION: The tension force of PC steel material 5 is transmitted from an anchor head 4 to a bearing plate 14 joined in the form of joined kites. The bearing plate 14 is brought into contact with concrete on a solid curved surface, the bearing force acts on a normal direction for the bearing force, and the dispersion state of a compression stress area and a spilt stress area acting on concrete can be controlled by the shape, the arrangement number and the intervals of the bearing plates 14. In order to relieve the stress concentration, the flange 15 of a curved surface changing curvature or a flat plate is provided on the edge end part of a semi-spherical bowl type or reversed bowl type bearing plate. Thereby fixing structure can be miniaturized, and PC structure member size optimal for the strength can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In a prestressed concrete structure, a tensioned prestressed steel material and a steel wire (hereinafter referred to as "PC steel material" and "steel wire") are supported by a concrete structure to fix the ends thereof. The present invention relates to an edge fixing structure.

[0002]

2. Description of the Related Art FIG.
FIG. 2 is a diagram of an end fixing structure of a PC steel material in a conventional PC structure. A concave portion 2 for fixing an end portion of a PC steel material is formed on an end surface of a concrete structure 1, and a supporting plate 3 is provided in the concave portion 2.
The anchor head 4 is supported on the end side of the concrete structure 1 of the support plate 3, and the end of the PC steel material 5 which is pierced through the anchor head 4 is anchored with a wedge 8 or a crimping grip (not shown). Generally, the head 4 is fixed, and after the fixing, the recess 2 is filled with a non-shrinkable mortar 7. A reinforcing steel bar 9 is embedded around the PC steel material. In such an end fixing structure of the conventional PC structure, a prestress is introduced into the concrete structure 1 through the support plate 3, and the stress spreads at a certain angle with respect to the tensile direction. Is transmitted to the concrete structure 1. FIG. 4 shows a general structure of the support plate 3 having a conventional fixing structure, and is a diagram formed by a rectangular flat plate. Then, the magnitude of the stress acting on the concrete structure 1 changes depending on the rectangular shape size 10. Therefore, the size of the supporting plate 3, the pitch 11, and the end opening 1 are set so that the stress of the concrete structure 1 is within the allowable stress level.
2 are determined.

As shown in FIG. 4, when the fixing structure as described above is arranged and the member size 13 of the concrete structure 1 is determined, the member size often exceeds the member size required for strength. Therefore, the dimensions of other members attached to the member determined in this way are often restricted, and there is a problem that the member becomes expensive. When the supporting plate 3 of the fixing structure is rectangular or small in size and the fixing structure, which is reduced in size by reducing the pitch 11 and the end opening 12 of the supporting plate 3, is placed in the concrete structure 1. Stress can greatly exceed the allowable stress of concrete. Therefore, the amount of the reinforcing steel bars 9 used for reinforcement shown in FIG. 3 also increases, and there is a problem that it becomes uneconomical.

The present invention has been made to solve such a problem, and the stress distribution state of the PC steel material 5 acting on the concrete structure 1 in the vicinity of the fixing plate 3 due to the tension can be controlled and the fixing can be performed. It is possible to reduce the size of the structure, and it is possible to set the optimum PC structural member size 13 in terms of strength without being affected by the dimensions of the fixing structure 10, the pitch 11, and the end holes 12, and to realize a PC that can be economically designed. An end anchoring structure for PC steel in a structure is provided.

[0005]

According to a first aspect of the present invention, there is provided a concrete structure in which one or a plurality of prestressing steel members are buried in a continuous kite-like manner in a concrete structure, and a prestressing steel material is provided on an end face of the concrete structure. An end fixing recessed portion is formed, and an anchor head is overlapped and supported on the end surface side of the concrete structure of the support plate in the recessed portion, and the end portion of the prestressed steel material that is tensioned by penetrating the anchor head is formed. Is anchored to an anchor head, and the concave portion is filled with non-shrink mortar. The end anchoring structure of a prestressed steel material in a prestressed concrete structure is characterized.

According to a second aspect of the present invention, the supporting plate through which the prestressed steel material as a part of the fixing structure according to the first aspect penetrates forms a bowl-shaped or inverted bowl-shaped rotating surface formed by rotating a curve. An end fixing structure for a prestressed steel material according to claim 1, characterized in that it is formed of a support plate provided with a curved surface or a flat flange having a different curvature at an edge portion thereof.

FIG. 1 is a view showing one embodiment of a fixing structure of the present invention.

In the fixing structure of the present invention, the tension of the PC steel material 5 is transmitted from the anchor head 4 to the supporting plate 14 connected in a continuous kite shape. The supporting plate 14 is in contact with the concrete on a three-dimensional curved surface, and the supporting pressure acts on the supporting plate in the normal direction, and the supporting pressure is dispersed by the number of the disposed supporting plates. The distributed state of the compressive stress region and the split stress region that act on can be controlled by the shape, the number, and the intervals of the support plates 14. In the vicinity of the edge of the hemispherical bowl-shaped or inverted bowl-shaped supporting plate, the degree of compressive stress acting on the concrete becomes excessive due to stress concentration. To alleviate this stress concentration,
A curved or flat flange 15 having a changed curvature is provided at the edge of a bowl-shaped or inverted bowl-shaped supporting plate on a hemispherical surface.

Therefore, since the stress distribution state due to the tension of the PC steel material 5 acting on the concrete structure 1 in the vicinity of the support plate 3 can be controlled, the fixing structure can be miniaturized, and the fixing structure 10, the pitch 11, the edge opening, and the like. The PC structure member size 13 which is optimal in terms of strength can be set without being affected by the size of the concrete structure 12, and the concrete structure 1 can be designed economically.

FIG. 2 is a front view of the continuous kite-shaped fixing structure.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing one embodiment of a fixing structure according to the present invention.

In the concrete structure 1, a supporting plate 14 is buried in which one or more PC steel materials penetrate in a continuous kite shape. The supporting plate 14 is integrally formed by casting or welding. When a plurality of supporting plates 14 are provided, their sizes may be the same or different. This is determined by the distribution plan of bearing stress. Then, a concave portion 2 for fixing the end portion of the PC steel material 5 is formed on the end surface of the concrete structure 1, and the anchor head 4 is overlapped on the end surface side of the concrete structure 1 in the concave portion 2 in which the supporting plate 14 is embedded. The end of the PC steel material 5 which has been tensioned by penetrating the anchor head 4 is held by a wedge 8 or a crimping grip (not shown).
The recess 2 is filled with a non-shrink mortar 7 to form a fixing section.

The support plate 14 has a semispherical bowl shape, and a flange 15 having a different curvature is provided at an edge. In this embodiment, the size of the support plate 14 is slightly smaller as the support plate disposed from the concrete surface to the inside. Further, the concrete structure 1 near the anchoring structure is provided with reinforcing bars 9 (spiral bars or grid bars) for preventing splitting. In this case, steel fibers may be mixed into concrete to prevent splitting.

[0015]

The effects of the present invention are as follows.

In the PC steel material end fixing structure of the present invention, one or more supporting plates are arranged in a continuous kite shape. The supporting plate has a bowl shape or an inverted bowl shape, and is a supporting plate having the same size or a different size. Further, the edge portion has a curved surface or a flat flange having a different curvature. By the shape and the number of the supporting plates, the stress distribution state due to the tension of the PC steel acting on the concrete structure near the fixing plate can be controlled, and the fixing structure can be miniaturized. Without being affected, it is possible to set the optimal PC structural member dimensions in terms of strength, and it is possible to design an economical concrete structure.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a fixing structure of the present invention.

FIG. 2 is a front view of a continuous kite-shaped fixing structure.

FIG. 3 is a view showing an end fixing structure of a PC steel material in a conventional PC structure.

FIG. 4 is a view showing a general structure of a support plate 3 of a conventional fixing structure, which is formed by a rectangular flat plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Concrete structure, 2 ... Recessed part, 3 ... Conventional bearing plate, 4 ... Anchor head, 5 ... PC steel, 6
... Sheath, 7 ... Non-shrink mortar, 8 ... Fixing wedge, 9
... Reinforcing bars (spiral bars), 10... Dimensions of fixing structure, 11... Pitch, 12...
C structural member dimensions, 14: bowl-shaped supporting plate, 15: flange of supporting plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaaki Okano 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Tohru Inomata 1-2-7 Moto-Akasaka, Minato-ku, Tokyo No. Kashima Construction Co., Ltd. (72) Inventor Hitoshi Goto 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Shunsuke Tanaka 1-2-7 Moto-Akasaka, Minato-ku, Tokyo No.Kashima Construction Co., Ltd.

Claims (2)

[Claims] 1. A supporting plate in which one or more prestressing steel materials penetrate in a concrete kite form in a continuous kite shape,
A concave portion for fixing an end portion of a prestressed steel material is formed on an end surface of the concrete structure, and an anchor head is overlapped and supported on the concave portion on the end surface side of the concrete structure of the support plate. Fix the end of the prestressed steel material that was pierced and tensioned to the anchor head,
An end anchoring structure of a prestressed steel material in a prestressed concrete structure, characterized in that the recess is filled with post-cast concrete. 2. A supporting plate through which a prestressed steel material, which is a part of the fixing structure according to claim 1, penetrates, forms a bowl-shaped or inverted bowl-shaped rotating surface formed by rotating a curve, and has an edge thereof. 2. The end fixing structure for a prestressed steel material in a prestressed concrete structure according to claim 1, comprising a support plate having a curved surface or a flat flange having a different curvature at an end.