JP2004190396A - Half precast floor slab and construction method of floor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate construction of a floor using a half precast floor slab. <P>SOLUTION: Cavity forming members used for the half precast floor slab are disposed integrally with the floor slab in a step of factory fabrication. Cast-in-place concrete can thereby be placed directly in construction, that is, a pre-concrete layer 9 is formed after welding the cavity forming members 7 to main reinforcements 3 simultaneously with truss reinforcements 5 to prevent the entry of concrete when placing the cast-in-place concrete later. In constructing the floor, these floor slabs are laid in the construction site, and the cast-in-place concrete is placed thereon to a desired thickness to form a floor face concrete layer 11. Neither time nor labor for disposing and fixing the cavity forming members 7 are thereby required. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a so-called half-precast floorboard in which a lower concrete layer is manufactured in a factory and an upper concrete layer is cast in place, and a method of constructing a floor using the floorboard.
[0002]
[Prior art]
For the floor of a concrete building, cast-in-place concrete is sometimes used, but in many cases, construction cost is reduced by adopting a precast floor plate manufactured in advance in a factory. However, since the thickness of precast slabs is fixed, it is difficult to respond to various floor thickness requirements, so the lower half is manufactured at a factory and laid at a construction site, A so-called half precast slab is used in which additional concrete is cast in place so as to have a desired floor thickness.
[0003]
As an example of a floor employing such a half precast floor plate, various structures are employed. As one example, as shown in FIG. 6, a floor 70 is formed by a half precast floor plate 71 and a void material. There is a so-called hollow member 73 and an additional concrete layer 75 cast at the construction site. The half precast floorboard 71 is manufactured in advance at the factory as described above, and its configuration is, for example, a plurality of main reinforcing bars 77 arranged in a form (not shown) and a plurality of reinforcing bars on these main reinforcing bars. It comprises a welded triangular truss 79 and a pre-concrete layer 81 filled at the factory so as to cover the lower part of the truss.
[0004]
The construction method of the floor 70 employing these half precast floor boards 71 is to dispose the above-mentioned hollow members 73 at the construction site to reduce the weight of the floor and the amount of concrete to be used, and to cast them into the concrete. At 75, it is buried in the floor. Since the hollow member 73 is intended to reduce the weight and the amount of concrete used as described above in principle, a thin hollow square steel pipe or the like is employed.
[0005]
As a second example, as shown in FIG. 7, a thin-walled cylindrical steel pipe is employed as the hollow member 93. Thin-walled cylindrical steel pipes are inexpensive and have a large cross-sectional area of being hollow per weight, but have the disadvantage that they tend to rise and displace when casting cast-in-place concrete. For this reason, the hollow member 93 is fixed on the truss bars 79 or the pre-concrete layer 81 before the cast-in-place operation using, for example, connecting means such as a support 95a, a beam 95b, and a band 95c.
[0006]
[Problems to be solved by the invention]
However, in the first example described above, the position of the hollow member 73 is likely to be displaced at the time of the cast-in-place operation, and in an extreme case, even the posture changes as shown by 73a in FIG. There is. In addition, the upper surface of the half precast floor plate 71 is difficult to walk, for example, the upper portion of the truss 79 is protruding. In the second example, the column 95a and the beam 95b are installed, and the hollow member 93 by the band 95c is further provided. These operations are extremely troublesome because the operations such as fixing the work are added.
[0007]
Therefore, an object of the present invention is to firstly provide a half-plext floorboard which does not require fixing work of a hollow member at a construction site. Second, it is an object of the present invention to provide a method for constructing a floor employing this floor plate, thereby reducing the cost of floor construction.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a half-precast floorboard comprising a pre-concrete layer having a predetermined thickness and a cavity forming member partially buried on one surface of the pre-concrete layer. By adopting the following means, the following functions and effects are produced.
[0009]
The half precast floorboard of the invention described in claim 1 is characterized in that the above-mentioned hollow forming member is cast on one surface of the above-mentioned pre-concrete layer at a predetermined thickness for embedding the hollow forming member. It is characterized in that it is formed so as to form a cavity into which the concrete does not enter. Since the half precast floorboard of the present invention is provided with a cavity forming member integrally with a pre-concrete layer or the like in advance at the factory manufacturing stage, after laying this at a building construction site, a cavity forming member as in the prior art is used. It is not necessary to dispose and fix the work. That is, since a desired floor thickness can be obtained by laying the half precast floorboard on the construction site and then directly casting the cast-in-place concrete, the construction cost of the floor using the half precast floorboard can be reduced. Here, the half precast floorboard refers to a floorboard as a semi-finished product manufactured in a predetermined shape at a factory, and the pre-concrete layer refers to a concrete layer formed in a factory in which main reinforcing bars and the like are embedded in advance.
[0010]
The invention described in claim 2 is embodied in the half precast floor panel according to claim 1. That is, this half precast floorboard has a predetermined plane shape and a pre-concrete layer in which the main reinforcing bars are buried, and a part of the pre-concrete layer is buried in the pre-concrete layer. A plurality of truss bars arranged in a state of being exposed on the upper surface, and juxtaposed between the truss bars, a part is embedded in the pre-concrete layer, and at least It is characterized in that it is constituted by a plurality of cavity forming members having a cross-sectional shape capable of forming a cavity in a portion exposed to the outside. Here, the truss bars refer to triangular bars provided on the main bars to reinforce the floor concrete layer formed by cast-in-place concrete. Since these truss bars are fixed on the main reinforcing bars, the placement of the cavity forming members prevents the lowering of the bonding strength between the concrete layer and the pre-concrete layer, which will be described later. Can be realized.
[0011]
According to a third aspect of the present invention, the cavity forming member is provided with an opening in a part of a cavity formed therein, and the opening is embedded in the pre-concrete layer. There is a feature. The cross-sectional shape of the cavity forming member is not particularly limited as long as the cavity can be formed, and the cavity may have a closed cross section by a circular tube, a square tube, or the like. However, if the cross-sectional shape of the cavity forming member is provided with an opening in the cavity and the opening side is buried in the pre-concrete layer, the production becomes easy, and the production cost of the half precast floor plate is reduced. It is advantageous for reduction. Since the opening formed in the lower part of the cavity forming member is closed by the pre-concrete layer at the factory manufacturing stage, there is a possibility that cast-in-place concrete will enter the cavity and reduce the area of the cavity. There is nothing.
[0012]
Further, the invention according to claim 4 provides the above-described cavity forming member such that a cavity portion can be formed with a single steel material over the entire length, thereby imparting a property as a reinforcing member against bending moment. There are some features. Since the half precast floor slabs were mainly intended to reduce the weight of the floor slabs and reduce the amount of concrete used, the prior art did not consider the strength factor. However, when the total length of the half precast floorboard increases, the bending moment acting on the halfprecast floorboard increases, so that the burden on the main reinforcing bar increases. Therefore, in the present invention, a steel member having high strength is adopted as the material of the cavity forming member, and the strength is improved by forming a single body over the entire length of the floorboard, thereby functioning as a reinforcing member against a bending moment acting in the longitudinal direction. There is a feature in the place where it is done. In addition, for those required to function as a reinforcing member, in addition to the above, increasing the thickness of the cavity forming member, adopting a tough steel material, forming a shape that increases the second moment of area, etc. It is desirable to meet some conditions.
[0013]
According to the invention as set forth in claim 5, when the invention is applied to a floor that does not require much strength, such as a floor plate having a small length or a floor having a small thickness, the strength against bending moment is left solely to the main reinforcing bar as before, This is to improve the original function of the precast floorboard. That is, the above-mentioned cavity forming member is constituted by a frame having a lower portion in which a plurality of aggregates that can be embedded in the pre-concrete layer are connected, and a wire mesh attached so as to cover the periphery of the frame. It is desirable that the wire mesh be a fine mesh that does not allow the gravel or the like of cast-in-place concrete to permeate. This half-precast floorboard reduces the weight of the cavity-forming member including the frame and the wire mesh, and can increase the volume of the cavity and is easy to manufacture. There is a characteristic in that it is more advantageous.
[0014]
According to a sixth aspect of the present invention, a method for constructing a floor using the half precast floor slab according to any one of the first to fifth aspects employs the following means. That is, this floor is constructed by laying a required number of the half precast slabs described above on the floor construction site, casting cast-in-place concrete to a desired thickness on the laying surface of these half precast slabs, and laying the floor concrete. Form a layer. Here, the floor concrete layer refers to a concrete layer formed by cast-in-place concrete to a thickness from the pre-concrete layer to the floor. In this construction method, the work at the construction site is only to cast the cast-in-place concrete on the laying surface of the half precast floorboard until the desired floor thickness is obtained, and in principle, other labor is not required, so the construction cost is low. It will be extremely cheap.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. First, a first example of the embodiment will be described with reference to FIGS. As shown in FIG. 2 (c), this half precast floor panel 1 lays this floor on an existing steel beam 15 in order, and forms a floor concrete layer 11 on the existing half precast floor panels 1, 1. Thus, the desired floor thickness (t) is obtained. The size of the half precast floorboard is usually about 0.9 m to 2 m in width and about 2 m to 5 m in length. As shown in FIG. 1, the structure of the half precast floor plate 1 is such that truss bars 5,... Are welded at predetermined intervals at predetermined positions on main reinforcing bars 3 arranged vertically and horizontally.
[0016]
As the truss bar 5, a steel bar having a diameter of 6 mm bent in a V shape and both ends bent outward to provide a welded portion is usually employed. Further, usually, the main reinforcing bar 3 employs a steel bar for a building material having a diameter of 10 mm, is arranged longitudinally, laterally and diagonally, and is fixed by binding or welding each intersection. Between the arranged truss bars 5,..., Cavity forming members 7,... Formed by forming a plate material into a U-shaped cross section, are juxtaposed in parallel to the longitudinal direction of the floor plate. Since the cavity forming member 7 is mainly intended to reduce the weight of the floorboard and the amount of concrete used, any material having a strength enough to withstand external pressure may be used. Therefore, as long as the object can be achieved, the material, thickness, and the like do not need to be considered. Here, a steel material is adopted as the cavity forming member 7, a welding portion is formed by bending an opening side end outward, and this portion is provided by welding to the main reinforcing bar 3.
[0017]
In this way, the main reinforcing bar 3, the truss bars 5, and the cavity forming member 7 are completely fixed to each other with the pre-concrete layer 9 so that the lower portions of the truss bars and the cavity forming member are submerged. The thickness (t1) of the pre-concrete layer 9 is usually about 70 mm, and the height of the portion where the cavity forming member 7 is exposed on the upper surface of the pre-concrete layer 9 is related to the height of the upper surface of the completed floor. It is preferable to be located at a distance of about 35 mm below the upper surface of the floor. That is, it is desirable that the thickness (t2) of the floor concrete layer 11 formed by cast-in-place is obtained by adding about 35 mm to the upper end of the cavity forming member 7. The half precast floorboard 1 is thus constituted by the above-described respective elements, and these are carried to a building construction site and used for floor construction.
[0018]
FIG. 2 shows a manufacturing procedure of the half precast floor panel 1 and a floor structure constructed using the same. FIG. 1A shows a state in which a main reinforcing bar 3 is provided on a formwork 13 at a factory, a truss bar 5 and a cavity forming member 7 are provided thereon, and these are fixed. FIG. 2B shows a pre-concrete layer 9 formed by pouring concrete into the mold 13 to a depth at which the lower portions of the truss bars 5 and the cavity forming members 7 are buried. The half precast floorboard 1 having the entire image as shown in FIG. 3 is obtained by removing the formwork 13 from this state. In addition, FIG. 2C shows that, as described above, the half precast floorboards 1 and 1 according to the present invention are juxtaposed on a beam 15 at a construction site and have a desired thickness (t) thereon. This shows a state in which the concrete is poured until the floor concrete layer 11 is formed. Although not shown, when pouring concrete at the construction site and placing the floor concrete layer 11, end covers are attached to the openings at both ends of the cavity forming member 7, and concrete enters through the openings. I try not to. Further, the half precast floorboards 1 and 1 may be formed in a state where the end lids are attached to the openings at both ends of the cavity forming member 7 in advance.
[0019]
In the cross section of the half precast floorboard 1 thus completed, the floor surface concrete layer 11 is formed up to the cavity forming member 7, so that the cavity S is defined inside each cavity forming member. Incidentally, the cross-sectional dimensions of the half precast floorboard 1 are such that the thickness (t1) of the pre-concrete layer 9 is about 70 mm, and the thickness (t2) of the floor concrete layer 11 is the upper surface and the upper end of the truss bar 5. Is about 35 mm, and the floor thickness (t) when the floor 1 is completed is about 250 mm to 300 mm. In the case of cast-in-place concrete in floor construction employing this half precast floor slab 1, the cast-in-place concrete is cast without the necessity of arranging and fixing hollow members as in the prior art. All that is required is to form the floor concrete layer to the desired thickness.
[0020]
Next, a second example of the embodiment will be described with reference to FIG. In the second example, as shown in FIG. 4A, the cavity forming member is made of an aggregate and a wire mesh, thereby realizing a reduction in weight and cost. That is, the cavity forming member 47 is composed of a frame 47a having a lower portion in which a plurality of aggregates that can be embedded in the pre-concrete layer 49 are connected, and a wire mesh 47b attached so as to cover the periphery of the aggregate. It is. The frame 47a is formed by assembling an aggregate such as a flat steel, an L-shaped steel, or a round bar into a tower shape and having a welded portion to the main reinforcing bar 43 at a lower end. The wire netting 47b should have a strength that can withstand the weight of the cast concrete, and a mesh that cannot pass the small stones of the cast concrete and the like should be used. The wire netting 47b is bent along the outer peripheral portion of the frame 47a and welded to the frame at important points to join them together. As shown in FIG. 4B, when the cavity forming member 47 is manufactured in a factory, the frame 47 a is welded together with the truss bars 45 at the lower end to the main reinforcing bar 43, and then the pre-concrete layer 49 is filled. Thus, a half precast floor plate 41 is provided. Since the cavity forming member 47 is fixed in a state where the frame 47a and the wire netting 47b are connected to each other, a cavity S extending inward in the longitudinal direction is formed inside the frame.
[0021]
The construction procedure at the construction site of the floor using the half precast floor panel 41 of the second example is the same as that of the first example. Since the cavity forming member 47 is simple to manufacture and can form a large cavity with a light weight, it contributes to a reduction in the amount of concrete used, a manufacturing cost, a weight saving of the floor, and the like. As the structure of the aggregate, various modified examples other than the illustrated one can be adopted. In addition, it is also possible to employ | adopt a mesh steel plate instead of the said wire mesh.
[0022]
Next, a third example of the embodiment will be described with reference to FIG. In the above description, it is assumed that the bending strength of the floorboard and the like for the cavity forming member are not normally expected. However, when the floorboard becomes large and the total length of the floorboard becomes 5 m to 6 m, a large bending moment acts, and it is becoming difficult to cope with this only with the main reinforcing bars. Therefore, in order to cope with such a large bending moment, the present invention is configured to strengthen the precast floorboard so that the cavity forming member can bear bending stress. As a condition for increasing the bending strength, here, at least the cavity forming member is formed in a shape capable of forming a cavity with a single steel material over the entire length, and the wall thickness is increased as much as possible and It is desirable that the ratio between the height (h) and the maximum width (b) be 1 or more. This increases the section modulus (Z) and the second moment of area (I).
The components of the half precast floorboard 21 are the same as those of the half precast floorboard 1 of the first example (see FIG. 1). As described above, the feature is that a large bending strength is given to the cavity forming member 27. That is, it is preferable to increase the thickness of the cavity forming member 27 and adopt a steel material having a high tensile strength (TS) as well as the cross-sectional shape.
[0024]
In the above description, the shape of the cavity forming member is a U-shaped cross-section, the opening portion of the cavity is downward, and the lower portion is buried in the pre-concrete layer to form the cavity. However, the shape of the cavity forming member is not limited to this. For example, it may be of a square pipe shape as employed in the section of the prior art, or of a circular cross section. When adopting such a shape as the cavity forming member, it is necessary to fix these members to the main reinforcing bar before forming the pre-concrete layer, but it is not necessarily required by welding, but by means such as binding. They may be combined. Further, the material of the cavity forming member is not limited to steel, but may be another material such as plastic or wood.
[0025]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, since construction of the floor which has a hollow part becomes very easy, the construction cost of a floor can be reduced. In addition, if a structure in which the bending strength of the cavity forming member is increased is adopted, the strength of the floor can be increased, so that a long half-precast floor plate can be adopted.
[Brief description of the drawings]
1A and 1B show a structure of a half precast floorboard according to a first example of an embodiment of the present invention, wherein FIG. 1A is a partially cutaway sectional view, and FIG. 1B is a partially cutaway perspective view.
FIGS. 2A and 2B show a method for manufacturing and constructing a half-precast floorboard according to a first example of an embodiment of the present invention, and FIG. 2A is a cross-section showing a state where a truss bar and a cavity forming member are fixed to a main reinforcing bar. (B) is a cross-sectional view showing a state in which a pre-concrete layer is formed on (a), and (c) is a cross-sectional view showing a state in which a half-precast floorboard is laid at a building site to cut a floor concrete layer. FIG.
FIG. 3 is a perspective view showing an entire configuration of a half precast floorboard according to a first example of an embodiment of the present invention.
4A and 4B show a second example of the embodiment of the present invention, wherein FIG. 4A is a perspective view of a cavity forming member, and FIG. 4B is a partially cutaway sectional view of a half precast floor plate.
FIG. 5 is a partially cutaway sectional view showing a half precast floorboard according to a third example of an embodiment of the present invention.
FIGS. 6A and 6B show a configuration of a half precast floorboard according to a first example of the prior art, where FIG. 6A is a partially cutaway sectional view and FIG. 6B is a perspective view.
FIG. 7 is a partially cutaway sectional view showing a configuration of a half precast floorboard according to a second example of the related art.
[Explanation of symbols]
1, 21, 41 Half precast floorboards 3, 23, 43 Main reinforcing bars 5, 25, 45 Truss bars 7, 27, 47 Cavity forming members 9, 29, 49 Pre-concrete layer 11 Floor surface concrete layer 47a Frame 47b Wire mesh S Cavity

Claims (6)

A pre-concrete layer having a predetermined thickness, and a cavity forming member partially buried in one surface of the pre-concrete layer,
The hollow forming member forms a hollow portion into which the concrete does not enter when concrete is poured into a predetermined thickness for embedding the hollow forming member on one surface of the pre-concrete layer. Half precast floorboard. A pre-concrete layer having a predetermined plane shape and burying the main reinforcing bar,
A plurality of truss bars partially buried in the pre-concrete layer and arranged so that the remaining portion is exposed on the upper surface of the pre-concrete layer,
A plurality of truss bars are juxtaposed and have a cross-sectional shape capable of forming a cavity at least in a portion exposed on the pre-concrete layer while being partially buried in the pre-concrete layer. A half precast floorboard comprising a cavity forming member. The cavity forming member according to any one of claims 1 and 2, wherein an opening is provided in a part of the cavity, and the opening is embedded in the pre-concrete layer. And half precast floorboards. The half precast floor plate according to any one of claims 1 to 3, wherein the cavity forming member is a single steel material formed in a shape capable of forming a cavity over the entire length. The cavity forming member according to any one of claims 1 to 3, wherein the cavity forming member includes a frame formed by combining a plurality of aggregates, and a wire mesh attached so as to cover the periphery of the frame. A half precast floorboard characterized by the following. A required number of half precast floorboards according to any one of claims 1 to 5 are laid on a floor construction site, and cast-in-place concrete is cast on a laying surface of these half precast floorboards to a desired thickness. A floor construction method using a half-precast floorboard, wherein a floor concrete layer is formed by forming the floor.

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