JP2000038797A - Semi-precast floor slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily construct a floor slab of high strength while preventing cost and weight increase. SOLUTION: A floor slab is formed out of a semi-precast floor slab 2 and concrete placed on the upper part thereof for burying a reinforcement bar 3. A distributing bar 5 and a PC steel material 6 orthogonal therewith are buried in a mold floor slab 4 made of the concrete of the semi-precast floor slab 2. The lower ends of a plurality of dowel reinforcement bars 7 made to an annular form are buried in the mold floor slab 4, and a reinforcement bar 3 is connected to the upper end of the dowel reinforcement bar 7. Also, a plurality of recesses 8 are formed on the lower surface of the mold floor slab 4. The PC steel material 6 is tightened, thereby introducing pre-stress to the mold floor slab 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semi-precast slab used when constructing an elevated road such as an expressway.

[0002]

2. Description of the Related Art Conventionally, a slab constituting an expressway or the like has been constructed by casting concrete at a site, or a precast slab has been manufactured in advance at a factory, and the precast slab has been laid. Was. By the way, since a large dynamic load is applied to the floor slab as the vehicle travels, a large number of reinforcing bars are arranged inside to secure the strength.

[0003]

In recent years, there has been a demand for further increasing the strength of the floor slab in consideration of earthquake resistance and the like. There has been a problem that the thickness has to be increased, and not only the weight of the floor slab is increased, but also the cost is greatly increased. In particular, if the weight of the precast slab increases, it will take a lot of labor to transport and install the precast slab.

The present invention has been made in view of the above circumstances, and provides a semi-precast slab capable of easily constructing a high-strength slab in which enormous cost increase and weight increase are suppressed. It is intended to be.

[0005]

In order to achieve the above object, a semi-precast slab according to claim 1 is a semi-precast slab used for constructing a road surface such as an elevated road, and is formed from concrete. Having a plate-shaped form floor slab, and a reinforcing bar embedded in the form floor slab, the form floor slab has a plurality of recesses formed on a lower surface thereof,
A PC steel material is provided in the inside thereof, a prestress is previously introduced by the PC steel material, and a reinforcing steel bar is disposed on the formwork slab portion and concrete is cast to form a slab. It is characterized by that. In this way, a reinforcing bar is buried inside, and a concrete slab is formed on the upper surface side to form a floor slab, that is, the concrete is laid on the upper surface side at the site and constructed. As a result, the weight is significantly reduced compared to the case where all are precast.Moreover, since a plurality of recesses are formed on the lower surface side of the formwork floor slab, further weight reduction is achieved. It is planned. In addition, since prestress is introduced into the formwork slab by the PC steel material arranged inside,
Even if a concave portion is formed on the lower surface side of the formwork slab to reduce the weight, sufficient strength is ensured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the semi-precast slab of the present invention will be described below with reference to the drawings. 1 to 3, reference numeral 1 denotes a floor slab that forms an elevated road such as an expressway. The slab 1 is composed of a semi-precast slab 2 and concrete C which is laid so as to embed a reinforcing steel bar 3 disposed on the upper part of the semi-precast slab 2.

Next, the semi-precast slab 2 constituting the slab 1 will be described. Semi-precast floor slab 2
As shown in FIG. 4 and FIG. 5, a formwork slab 4 made of concrete, a force bar 5 embedded in the formwork slab 4, and a And a PC steel material 6 arranged in a direction perpendicular to the direction. The lower ends of a plurality of ring-shaped dowels 7 are buried in the formwork slab 4, and the upper ends of these dowels 7 are formed on the formwork slab 4.
Protruding from the upper surface side. The PC steel material 6 is passed through the dowel bar 7 in the formwork slab 4. Further, a plurality of recesses 8 are formed on the lower surface of the formwork slab 4. A prestress is previously introduced into the form slab 4 by tensioning the PC steel material 6.

[0008] In addition, the formwork floor slab 4 has, on its upper side,
The reinforcing bar 3 is provided. The main reinforcing bar 3a constituting the reinforcing reinforcing bar 3 is passed through the dowel bar 7, and the distribution bar 3b.
Is disposed orthogonal to the main muscle 3a, and is attached to the tip of the dowel muscle 7 by fixing it with a binding wire or the like.

Next, the semi-precast floor slab 2 having the above structure is used.
The case where the floor slab 1 is constructed will be described. (1) First, a semi-precast slab 2 is laid on a bridge girder, and a formwork (not shown) is installed below the semi-precast slabs 2. (2) Next, concrete C is cast on the upper surfaces of the semi-precast floor slab 2 and the formwork. At this time, the concrete C is sufficiently covered on the reinforcing steel bar 3 provided on the upper part of the semi-precast floor slab 2. In this way, the slab 1 in which the semi-precast slab 2 and the cast concrete C are integrated is constructed.

[0010] As described above, according to the semi-precast slab 2, the reinforcing bar composed of the distribution bars 5 is buried inside, and the concrete C is cast on the upper surface side to form the slab 1. Since it has the frame floor slab portion 4, that is, it is constructed by casting concrete C on the upper surface side at the site, it is possible to significantly reduce the weight as compared with the case where all are precast. Further, since the plurality of recesses 8 are formed on the lower surface side of the formwork floor slab 4, further weight reduction can be achieved, and labor during transportation and construction can be greatly reduced.

Further, since the prestress is introduced into the formwork slab portion 4 by the PC steel material 6 disposed inside,
Even if the concave portion 8 is formed on the lower surface side of the formwork floor slab portion 4 to reduce the weight, sufficient strength can be secured. This allows
Higher strength can be achieved without increasing the thickness, and a floor slab excellent in earthquake resistance can be constructed without increasing the cost.

Although the concrete C is cast on the upper surface, the concrete C can be cast at the same time as the concrete C is cast on the joint, so that it does not require much labor. Construction work can be performed. Further, in the above example, the reinforcing bar 3 provided on the upper part of the formwork slab 4 was welded and fixed to the dowel bar 7 in advance, but the reinforcing bar 3 Of course, it may be installed on the upper part.

[0013]

As described above, according to the semi-precast slab of the present invention, the following effects can be obtained. According to the semi-precast slab according to claim 1, a reinforcing bar is buried inside, and a concrete slab is cast on the upper surface side, and the slab has a formwork slab portion. Since it is constructed by casting concrete, it is possible to significantly reduce the weight compared to the case where all is precast, and furthermore, a plurality of recesses are provided on the underside of the formwork slab. Is formed, the weight can be further reduced, and labor during transportation and construction can be significantly reduced. In addition, since prestress is introduced into the formwork slab by the PC steel material arranged inside, sufficient strength is secured even if a concave portion is formed on the lower surface side of the formwork slab to reduce the weight. can do. Thereby, high strength can be achieved without increasing the thickness, and a floor slab excellent in earthquake resistance can be constructed without increasing the cost. In addition, concrete is cast on the upper surface, but since this concrete can be cast at the same time as concrete is cast on joints, construction work can be performed without much trouble. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view of a part of a slab constructed using a semi-precast slab illustrating a configuration and a structure of a semi-precast slab according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the floor slab along a force distribution bar for explaining a configuration and a structure of the semi-precast slab according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the floor slab along a PC steel material for explaining the configuration and structure of the semi-precast slab according to the embodiment of the present invention.

FIG. 4 is a perspective view of the semi-precast slab illustrating the configuration and structure of the semi-precast slab according to the embodiment of the present invention.

FIG. 5 is a diagram showing a distribution bar, a PC steel material, and an inner structure for explaining an internal structure of a formwork slab of a semi-precast slab according to an embodiment of the present invention.
It is a perspective view of a gibber and a reinforcing bar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Floor slab 2 Semi-precast slab 3 Reinforcing reinforcing bar 4 Formwork slab part 5 Reinforcing bar (reinforcing bar) 6 PC steel 8 Recess C concrete

Claims (1)

[Claims] 1. A semi-precast slab used when constructing a road surface such as an elevated road, wherein a plate-shaped form slab made of concrete and a reinforcing bar embedded in the form slab. The formwork slab has a plurality of recesses formed on a lower surface side thereof, a PC steel material provided therein, and a prestress is introduced in advance by the PC steel material. A semi-precast slab, characterized in that a reinforcing slab is arranged on a frame slab and concrete is cast to form a slab.