JPH06108420A - Precast floor slab - Google Patents

Abstract

PURPOSE:To reduce the amount used of special concrete by projecting hoop-like joining reinforcement projections from both side ends of precast concrete in two steps in a thick direction to form. CONSTITUTION:Both ends of a pair of up and down reinforcing bars 17 and 18 extending widthwise of precast concrete 8 are folded to form loop sections 19 on both ends, and the reinforcing bars 17 and 18 are buried inside the concrete 8 in a multistage along lengthwise to form precast slabs 23 so that a part of the loop sections 19 is projected from both side ends. When the floor slabs 23 are joined, adjacent floor slabs 23 are so arranged that hoop-like joining reinforcement projections 20 and 21 lap each other, and after the reinforcing bars are arranged so as to join between the projections 20 and 21, special concrete is filled between the floor slabs 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast slab used as a reinforced concrete slab for bridges.

[0002]

2. Description of the Related Art As shown in FIG. 3, a reinforced concrete floor slab 1 for a bridge comprises a precast floor slab 2 produced in a factory in a desired shape at a predetermined interval above a main girder 3. It is formed by filling a special concrete 4 such as ultra-quick concrete between adjacent precast floor slabs 2 and curing it.

In the figure, reference numeral 5 is a pavement laid on the upper portion of the reinforced concrete floor slab 1.

As shown in FIGS. 4 and 5, the precast floor slab 2 has a reinforcing bar 6 bent at both ends so that the whole becomes an elliptical shape. It has a structure in which it is embedded in multiple stages in the longitudinal direction so as to project in a hoop shape from 9.

When joining the precast floor slabs 2, the adjacent precast floor slabs 2 are arranged so that the hoop-shaped reinforcing bar projecting portions 10 projecting from the side end surfaces 9 of the adjacent precast floor slabs 2 wrap and are joined together. After arranging a plurality of reinforcing bars 11 extending in the longitudinal direction so as to connect the reinforcing bar projecting portions 10, the special concrete 4 is filled as described above.

Thus, the adjacent precast floor slabs 2
By filling the special concrete 4 between them, the precast floor slabs 2 adjacent to each other are integrated, and the special concrete 4 filled in the hoop-shaped joining reinforcing bar projecting portion 10 and the wrap portion of the joining reinforcing bar projecting portion 10 is integrated. Thus, a tensile force in the width direction 12 that acts between the precast floor slabs 2 is applied.

[0007]

However, the above-mentioned conventional precast floor slab 2 has the following problems.

That is, since the special concrete 4 such as ultra-quick concrete for joining the precast floor slabs 2 is expensive, which is about 10 times as high as that of normal concrete, the space 13 between the precast floor slabs 2 is narrowed. Therefore, there is a demand to reduce the amount of the special concrete 4 used as much as possible. However, as shown in FIG. 6, by shortening the straight portion 14 of the hoop-shaped joining reinforcing bar projecting portion 10, the adjacent precast floor slabs are shortened. When the gap 13 between the two is narrowed, the shape of the lap portion between the joint reinforcing bar projecting portions 10 approaches a ring shape when viewed from the longitudinal direction, and therefore when an external force 15 acts on the hardened special concrete 4 portion. , Bending in the direction of arrow 16 centering on the substantially concrete special concrete 4 existing in the lap portion that receives the tensile force in the width direction 12 It means that the force is generated, it is impossible to narrow too the gap 13 between the precast slab 2.

In view of the above situation, it is an object of the present invention to provide a precast floor slab capable of reducing the amount of special concrete used by reducing the distance between the precast floor slabs. .

[0010]

DISCLOSURE OF THE INVENTION The present invention relates to a precast floor slab, characterized in that hoop-shaped reinforcing bar projections for joining are formed in two steps in the thickness direction from both end surfaces of the precast concrete. Is.

[0011]

The operation of the present invention is as follows.

When joining the precast floor slabs, the adjacent precast floor slabs are arranged so that the hoop-shaped joining reinforcing bar projecting portions projecting in two steps in the thickness direction from the side end faces of the precast floor slabs respectively wrap and Fill with special concrete such as ultra-quick concrete and cure.

According to the present invention, since the hoop-shaped joining reinforcing bar projecting portion is projected in two steps in the thickness direction from the side end surface of the precast floor slab, the pulling in the width direction acting between the adjacent precast floor slabs is performed. The force is applied to the lap between the reinforcing bar projections for joining and the special concrete existing in the lap,
Since it can be received by the lap part of the joint reinforcing bar projections and the two parts of the special concrete existing in the lap part, even if an external force acts on the hardened special concrete, the above two parts resist the external force and the special part As it prevents bending stress from occurring inside the concrete,
It is possible to reduce the amount of special concrete by narrowing the space between precast floor slabs without any problems.

[0014]

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

1 and 2 show an embodiment of the present invention.

Further, in the figure, the same components as those shown in FIGS. 3 to 6 are designated by the same reference numerals, and the explanation thereof will be omitted. Hereinafter, only the constitution unique to the present invention will be explained. go.

Width direction 12 of precast concrete 8
Both ends of a pair of upper and lower rebars 17 and 18 extending to be folded back to form loop portions 19 at both ends, and the respective rebars 17 and 18 are placed inside the precast concrete 8 so that a part of the loop portion 19 projects from both end faces 9. By embedding in a multi-tiered manner in the longitudinal direction, the precast floor slab 23 in which the hoop-shaped joining reinforcing bar projecting portions 20 and 21 project from the both end surfaces 9 of the precast concrete 8 in two steps in the thickness direction 22 is formed.

Next, the operation will be described.

When the precast floor slabs 23 are joined together, the adjacent precast floor slabs 23 are projected from the side end surface 9 in the thickness direction 22 in two steps to form a hoop-like joining reinforcing bar projecting portion 2.
0 and 21 are arranged so as to wrap, and a plurality of reinforcing bars 11 extending in the longitudinal direction so as to connect between the reinforcing bar projecting portions 20 and 21 of the respective stages are arranged appropriately, and then the precast floor slab 23 is superposed. Special concrete 4 such as immediate hardened concrete is filled and hardened.

According to the present invention, since the hoop-shaped joining reinforcing bar projecting portions 20 and 21 are projected from the side end surface 9 of the precast floor slab 23 in two stages in the thickness direction 22, the space between the adjacent precast floor slabs 23 is increased. The tensile force in the width direction 12 that acts on the special concrete 4 existing in the lap portion and the lap portion of the joint reinforcing bar protrusions 20 and the special concrete existing in the lap portion and the lap of the joint reinforcing bar protrusions 21. Since it can be received by the two parts of No. 4, even when an external force 15 acts on the hardened special concrete 4, the above two parts resist the external force and prevent bending stress from being generated inside the special concrete 4. Therefore, the space 13 between the precast floor slabs 2 can be narrowed without any problem, and the amount of the special concrete 4 used can be reduced.

The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0022]

As described above, according to the precast floor slab of the present invention, the excellent effect that the space between the precast floor slabs can be narrowed and the amount of the special concrete used can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is a cutaway front view of an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a state in which the precast floor slabs of FIG. 1 are joined together.

FIG. 3 is a partially cutaway perspective view showing a joint portion of a reinforced concrete floor slab of a bridge.

FIG. 4 is a cutaway front view of a conventional precast floor slab.

5 is a partially enlarged view showing a state in which the precast floor slabs of FIG. 4 are joined together.

FIG. 6 is a partially enlarged view showing a case where the joining interval is narrowed by using the precast floor slab of FIG. 4.

[Explanation of symbols]

 8 Precast concrete 9 Side end face 20,21 Reinforcing bar protrusion for joining 22 Thickness direction

Claims (1)

[Claims] 1. A precast floor slab characterized in that hoop-shaped joining reinforcing bar projecting portions are projectingly formed in two steps in the thickness direction from both end surfaces of the precast concrete.