JPH07305443A - Structure of precast reinforced concrete - Google Patents

Abstract

PURPOSE:To increase workability and save labors and facilitate the strength control, by arranging a part of main reinforcements of beams in a slab and arranging shear transfer rods between the main reinforcements of the beam upper end in the slab. CONSTITUTION:A half-precast beam A is constituted of a high strength concrete. A part of the main reinforcements of the beam upper end are arranged in a slab. Shear transfer rods 6, 6 are arranged from the beam web into the slab so as to cross at right angles against the main reinforcements in the slab, between these reinforcements. Then ordinary strength concrete is placed in the post-casting position B. In this way, The effectiveness of a slab against a shearing force is increased and hence, even if concrete having a lower strength than the concrete of a half-precast beam A is used in a post-casting position B, a shearing resistant performance can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of precast reinforced concrete beams.

[0002]

2. Description of the Related Art In the conventional precast reinforced concrete construction, the concrete B of the post-casting portion is also cast with the same strength as the half precast beam portion A. (See FIGS. 6 and 7) In the figures, a is a beam main bar, b is a shear reinforcing bar, c is a floor main bar, and d is a floor force distributing bar.

Therefore, the precast half-beam made of high-strength concrete is also cast with high-strength concrete at the post-casting portion on site.

[0004]

Since high-strength concrete has poor workability in plastering work and the like, and strength control is difficult, it is not easy to handle on site. The present invention has been proposed in view of the above problems of the prior art, and its purpose is to provide a structure of a precast reinforced concrete beam with increased workability, labor saving, and easy strength management. In point.

[0005]

In order to achieve the above object, the structure of a precast reinforced concrete beam according to the present invention is such that a half precast beam portion is made of high strength concrete, and a part of the beam upper end main bar extends over the slab. The shear force transmission bars are arranged in the slab from the beam web section at right angles to the beam upper main bars in the slab, and normal strength concrete is placed in the post-casting section. There is.

[0006]

According to the present invention, since the beam top main bar is laid out not only to the beam end but also inside the floor, the main bar in the floor and the shearing force laid out orthogonally to the bar The effectiveness of the slab is increased by transmitting the shear force in the slab surface direction by the transmission muscles, and the shear resistance performance is secured even if concrete having a strength weaker than the beam concrete of the precast portion is used for the post-casting portion.

The use of ordinary strength concrete as the post-cast concrete improves workability and facilitates strength management on site.

[0008]

The present invention will be described below with reference to the illustrated embodiments. 1 and 2 show a first embodiment of the present invention, in which a half precast beam portion A is manufactured using high-strength concrete as in the prior art. 1 is a beam main bar, 2 is a shear reinforcement bar, 3 is a floor bar, 4 is a floor force bar, and 5 is a beam upper end bar which is bar-reinforced in the floor, and is for transmitting shear force in the slab from the beam web part. , Arranging the shear force transmitting muscles 6 between the beam main muscles 1,
Normal strength concrete is placed in the post-casting portion B. After that, finish the upper surface. Reference numeral 7 in the figure denotes a force transmission line between the rear striking portion B and the half precast beam portion A.

FIG. 3 and FIG. 4 show a second embodiment of the present invention, in which a force transmission bar 7 between the post-strike part B and the half precast beam part A is arranged between the shear reinforcement bars 2 of the beam. Has been done.
FIG. 5 schematically shows transmission of shearing force in the precast reinforced concrete beam.

[0010]

In the structure of the precast reinforced concrete beam according to the present invention, a part of the beam upper end rebar of the half precast beam portion is arranged over the slab, and the beam upper end rebar in the slab is orthogonal to this. The shear transfer reinforcement from the beam web section to the slab improves the effectiveness of the slab against shearing, and the shear resistance even when using concrete with weaker strength than the concrete of the half precast beam section for the post-casting section. Performance is secured.

As described above, the use of ordinary concrete for the post-casting portion improves the workability and saves labor, and since the concrete to be handled at the site is the ordinary concrete, the strength can be easily controlled. , Quality is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the structure of a precast reinforced concrete beam according to the present invention.

FIG. 2 is a plan sectional view of FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a plan sectional view of FIG.

5 (a), (b), (c), (d), and (e) are schematic diagrams showing the flow of shear force in the structure of the precast reinforced concrete beam according to the present invention.

FIG. 6 is a cross-sectional view showing a conventional structure.

7 is a plan sectional view of FIG.

[Explanation of symbols]

A Half-precast beam part B Battered part 1 Beam main bar 2 Shear reinforcing bar 3 Floor main bar 4 Floor force distribution bar 5 Beam top main bar 6 Shearing force transmission bar 7 Reinforced in floor Force transmission muscle between

Claims (1)

[Claims] 1. A half precast beam part is made of high-strength concrete, a part of a beam upper end main bar is laid in a slab, and a beam web part is orthogonal to the beam upper end main bar in the slab. The structure of precast reinforced concrete beams is characterized in that shear force transmission bars are arranged in the slab and ordinary strength concrete is placed in the post-casting part.