JPH0610404A - Precast concrete beam - Google Patents

Abstract

PURPOSE:To increase the shearing yield strength of the joint between a beam and cast-in-place concrete by providing a plurality of dowels protrusively on the upper surface of precast concrete from which part of each stirrup is projected, each of the dowels having a flange piece. CONSTITUTION:Precast concrete 1a is provided along beam length except for the thickness of a floor slab and part of each stirrup 2, 2 is projected to the upper surface of the concrete la to form a precast concrete beam 1. A plurality of dowels 3... are provided protrusively on the upper surface of the precast concrete 1a and are each provided with a flange piece at a predetermined portion. The shearing yield strength of the joint between the precast concrete beam 1 and cast-in-place concrete is increased by the dowels 3 and the flange piece restrains rotation of the dowels 3 due to shearing displacement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast concrete beam having a dowel on its upper surface.

[0002]

2. Description of the Related Art In order to make up for an extreme labor shortage in recent years, or in order to improve workability and economy, precasting of reinforced concrete columns, beams, walls, floor slabs, etc. has been advanced. Of these, the precast concrete beams are
The beam slab except the floor slab was made of precast concrete, and some of the stirrups protruded on the upper surface,
So-called half PC beams are used.

This precast concrete beam is
As shown in (1) and (2) of the figure, the concave portion 10 and the dowel 20 are formed on the upper surface for joining with the floor slab and enhancing shear reinforcement.
Is provided. Of these, the dowel 20 shown in (2) is
It is embedded while being supported by the reinforcing bars 40 of the beam 30.

[0004]

However, a precast concrete beam having a concave portion on its upper surface has a problem that it is difficult to form the concave portion and the workability is poor, and a precast concrete beam having a dowel has the following problems. There was a problem that it was difficult to dispose the dowel if there were no reinforcing bars at appropriate positions when suspending the dowel. The present invention has been made in view of the above problems, and its purpose is to enhance the shear strength of the striking surface of the floor slab, and good workability,
It is to provide a precast concrete beam that can be formed by a simple method.

[0005]

Means for Solving the Problems The gist of the present invention for solving the above problems is to use precast concrete up to the beam slab except for the thickness of the floor slab. In the projecting precast concrete beam, a plurality of dowels are provided on the upper surface of the precast concrete, and the dowels are provided with collar pieces at predetermined positions.

[0006]

Since the dowel on the upper surface of the precast concrete beam is provided with the collar piece at a predetermined position, it is easily and accurately arranged on the upper surface of the beam to surely increase the shear strength. In addition, this collar piece can suppress rotation due to shear displacement.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of a precast concrete beam, FIG. 2 is a sectional view of the same, FIG. 4 is a sectional view of a floor slab placed, and FIG. 5 is a perspective view of a dowel.

FIG. 1 shows a precast concrete beam 1 according to the present invention. The precast concrete 1a is formed up to the beam slab except for the thickness of the floor slab. , A plurality of dowels 3 are provided on the upper surface. After the concrete 1a is cast in the mold, the dowel 3 is arranged so as to be floated on the upper surface of the concrete 1a by the brim piece 3a before it is hardened, and is fixed by hardening the concrete 1a.

As shown in FIG. 4, the dowel 3 is provided with a flange piece 3a at the center of a steel cylindrical body 3b. The upper part of the dowel 3 projects from the upper surface of the concrete 1a with the flange piece 3a as a boundary, and the lower part It is buried in concrete.

In FIG. 3A, a precast concrete beam 1 of the present invention having a dowel 3 is bridged between columns, and a precast concrete floor slab 4 is installed on the beam.
A floor slab 6 is formed by casting a cast-in-place concrete 5 on it and on the precast concrete beam 1. This allows precast concrete beams 1
The floor slab 6 and the floor slab 6 are integrally formed. The dowel 3 enhances the shear resistance of the striking surface, and the collar piece 3a also suppresses rotation due to displacement. In addition (2), dowel 3 is 2
This is an embodiment arranged in rows, and this is not limited to two rows, and it is of course possible to arrange more than that, and the arrangement method is not limited to parallel arrangement, and the arrangement may be made in a staggered manner or any other method. can do.

4 (1) to 4 (4) show another embodiment of the dowel 3, and FIG. 4 (1) shows a case in which a collar 3a is provided on both sides of a rectangular cylindrical body 3b. (2) is formed by connecting the rectangular cylindrical body 3b with the collar piece 3a.
Further, (3) is a projecting flange piece 3a on both sides of the vertical piece 3c, and (4) is a cross piece 3d provided with a flange piece 3a at the corners thereof. Shall be used according to the shape and size of. Further, the dowel 3 of the present invention is not limited to the above (1) to (4), and is not limited to the shape as long as it has the collar piece 3a, and the material thereof is the above. The material is not limited to steel, but may be ceramic or plastic.

[0012]

EFFECTS OF THE INVENTION In a precast concrete beam formed by precast concrete up to the beam except the thickness of the floor slab, and a part of the stirrups projecting on the upper surface of the precast concrete, a plurality of dowels are formed on the upper surface of the precast concrete. By providing a collar piece at a predetermined position, the shear strength of the joint between the precast concrete beam and the cast-in-place concrete is enhanced by the dowel,
Moreover, rotation of the dowel is suppressed by the collar piece, and the dowel can be easily arranged after the concrete is poured, and the workability can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a precast concrete beam.

FIG. 2 is a cross-sectional view of a precast concrete beam.

3 (1) and (2) are cross-sectional views of a precast concrete beam in which a floor slab is constructed.

FIG. 4 is a perspective view of a dowel.

FIG. 5 is a perspective view showing another embodiment of the dowel.

FIG. 6 is a cross-sectional view of a conventional precast concrete beam.

[Explanation of symbols]

 1 Precast concrete beams 2 Stirrups 3 Dowels 3a Collar pieces

[Procedure amendment]

[Submission date] August 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

FIG. 4 (1) shows that the precast concrete beam 1 of the present invention having the dowels 3 is bridged between columns, and a precast concrete floor slab 4 is laid on the beam.
A floor slab 6 is formed by casting a cast-in-place concrete 5 on it and on the precast concrete beam 1. This allows precast concrete beams 1
The floor slab 6 and the floor slab 6 are integrally formed. The dowel 3 enhances the shear resistance of the striking surface, and the collar piece 3a also suppresses rotation due to displacement. In addition (2), dowel 3 is 2
This is an embodiment arranged in rows, and this is not limited to two rows, and it is of course possible to arrange more than that, and the arrangement method is not limited to parallel arrangement, and the arrangement may be made in a staggered manner or any other method. can do.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

5 (1) to 5 (4) show another embodiment of the dowel 3, and FIG. 5 (1) shows a case in which a flange 3a is provided on both sides of a rectangular cylindrical body 3b. (2) is formed by connecting the rectangular cylindrical body 3b with the collar piece 3a.
Further, (3) is a projecting flange piece 3a on both sides of the vertical piece 3c, and (4) is a cross piece 3d provided with a flange piece 3a at the corners thereof. Shall be used according to the shape and size of. Further, the dowel 3 of the present invention is not limited to the above (1) to (4), and is not limited to the shape as long as it has the collar piece 3a, and the material thereof is the above. The material is not limited to steel, but may be ceramic or plastic.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 is a perspective view of a dowel.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

4 (1) and (2) are cross-sectional views of a precast concrete beam in which a floor slab is constructed.

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A precast concrete beam having a floor slab up to the beam slab except for the thickness of the floor slab, wherein a part of stirrups is projected on the upper surface of the precast concrete, and a plurality of dowels are formed on the upper surface of the precast concrete. A precast concrete beam, wherein the dowel is provided with a collar piece at a predetermined position.