JP6418805B2 - Embedded formwork for floor slabs - Google Patents

Description

  The present invention relates to an improvement of an embedded form for a floor slab.

  When the upper slab of a box culvert or the slab of a pier is made to have a large slab thickness and a large span, it is necessary to support the formwork with a large support that can withstand the concrete loading load. However, the installation of such support works not only extends the construction period but also limits the work in the space under the floor slab, and further requires a large scaffold for its installation and dismantling.

  As an embedded formwork, the slab part and the rib part manufactured separately from this and the part joined to the slab part are curved surfaces are joined to cause the slab part and the rib part to bend. (See Patent Document 1).

  According to this Patent Document 1, it is possible to generate a compressive stress on the lower surface of the slab portion when the rib portion and the slab portion are joined together, thereby generating the lower surface of the slab portion when placing the cast-in-place concrete. Since the tensile stress can be relaxed, it is possible to increase the span of the embedded formwork, and to eliminate or simplify the support work.

  However, in the concrete floor slab, the reinforcing bars are usually arranged on the upper side and the lower side, respectively, but in the case of Patent Document 1, the rib portion obstructs the arrangement of the lower reinforcing bars. If the lower reinforcement bars are arranged avoiding the rib portion, the distance between the lower reinforcement bars and the lower surface of the floor slab increases, so the effective height of the reinforcement bars becomes smaller and reinforcement by reinforcing bars The effect is reduced. If the height of the rib portion is reduced, the distance between the lower distribution bar and the lower surface of the floor slab can be reduced. However, since the bending rigidity and cross-sectional performance of the embedded formwork are reduced, the height of the rib portion is reduced. There is a limit to reducing the size.

JP 2010-248746 A

  The main problem to be solved by the present invention is that this kind of buried form can be easily and appropriately arranged with the arrangement of the reinforcing bars while being able to relieve the tensile stress generated during the placement of cast-in-place concrete. It is in the point to.

In order to achieve the above object, according to the present invention, from the first aspect, an embedded formwork for floor slabs is an embedded formwork in which cast-in-place concrete is placed on the upper side to constitute a floor slab. ,
A formwork bottom plate made of precast reinforced concrete, which is integrally provided with a steel lower rib material arranged along the length direction of the floor slab, as an embedded metal;
An upper rib member made of steel provided along the length direction on the mold bottom plate;
A plurality of connecting members for connecting the lower rib member and the upper rib member;
Among the plurality of connecting materials, the connecting material and the upper side connecting the left end portion of the lower rib member, the left end portion of the upper rib member, and the right end portion of the lower rib member and the right end portion of the upper rib member. The rib member can be temporarily fixed by a shaft body having an axis line along the width direction of the floor slab and a shaft hole through which the shaft member passes,
Among the plurality of connecting members, a connecting member other than the connecting member connecting the left end portion of the lower rib member and the left end portion of the upper rib member and the right end portion of the lower rib member and the right end portion of the upper rib member. The material and the upper rib member can be permanently fixed from the temporarily fixed state while applying an upward force to a position in the middle in the length direction of the mold bottom plate with the shaft body as a fulcrum .

  With the upper rib material integrated with the lower rib material, the embedded formwork can be supported without requiring any special support work. Further, since the lower rib member and the upper rib member are connected by the connecting material, the distribution bars can be easily and appropriately arranged through the gap between the connecting materials. Further, according to the above configuration, before the upper rib member is permanently fixed to the mold bottom plate, the left and right shafts can be lifted up between both ends of the mold bottom plate, and as described above. In the lifted-up state, it is possible to permanently fix the upper rib material to the mold bottom plate, and thereby it is possible to relieve the tensile stress generated in the mold bottom plate when placing on-site concrete.

In order to achieve the above object, according to the present invention, from the second point of view, an embedded formwork for floor slabs is an embedded formwork in which cast-in-place concrete is placed on the upper side to constitute a floor slab. ,
Formwork bottom plate made of precast reinforced concrete,
An upper rib member made of steel provided along the length direction on the mold bottom plate;
A plurality of connecting members that connect the reinforcing bars that are part of the main reinforcing bars of the mold bottom plate and the upper rib material;
Among the plurality of connecting members, the connecting member that connects the left end portion of the reinforcing bar and the left end portion of the upper rib member and the right end portion of the reinforcing bar and the right end portion of the upper rib member, and the upper rib member, With the shaft body along the axis in the width direction of the floor slab and the shaft hole through which it can be temporarily fixed ,
Among the plurality of connecting members, the connecting member other than the connecting member that connects the left end portion of the reinforcing bar, the left end portion of the upper rib member, the right end portion of the reinforcing bar, and the right end portion of the upper rib member, and the upper portion. The rib member can be permanently fixed from the temporarily fixed state while applying an upward force to a position in the middle in the length direction of the mold bottom plate with the shaft body as a fulcrum .

  With the upper rib material integrated with the reinforcing bar, the embedded formwork can be supported without requiring any special support work. In addition, since the reinforcing bar and the upper rib member are connected by a connecting material, the distribution bar can be easily and appropriately arranged through the gap between the connecting materials. Further, according to the above configuration, before the upper rib member is permanently fixed to the mold bottom plate, the left and right shafts can be lifted up between both ends of the mold bottom plate, and as described above. In the lifted-up state, it is possible to permanently fix the upper rib material to the mold bottom plate, and thereby it is possible to relieve the tensile stress generated in the mold bottom plate when placing on-site concrete.

  In the invention according to the first aspect and the invention according to the second aspect, it is preferable that the mold bottom plate is provided with an insert anchor at a position in the middle of the length direction. One of them.

  The embedded formwork according to the present invention has a structure that can relieve the tensile stress generated during the placement of cast-in-place concrete, and can easily and appropriately place the reinforcing bars on the formwork bottom plate. It has a feature that makes it easy to build floor slabs.

FIG. 1 is a block diagram showing the construction process of a box culvert according to an embodiment of the present invention, and shows a state in which a bottom plate is constructed. FIG. 2 is a block diagram showing the construction process of the box culvert, and shows the construction of the side wall following the state of FIG. FIG. 3 is a block diagram showing a construction process of the box culvert, and shows a state in which a beam material is provided on the upper portion of the side wall following the state of FIG. FIG. 4 is a perspective configuration diagram showing a state in which a formwork bottom plate of an embedded formwork constituting an upper floor slab of a box culvert is installed between the left and right beam members. FIG. 5 is a perspective configuration diagram illustrating a state in which the upper rib member is temporarily fixed to the formwork bottom plate from the state of FIG. 4. FIG. 6 is a front view of the state shown in FIG. FIG. 7 is a perspective configuration diagram showing a state in which lift-up means is attached to the embedded formwork from the state of FIG. FIG. 8 is a front configuration diagram of the state of FIG. FIG. 9 is a front configuration diagram showing a state in which the mold bottom plate and the upper rib member are finally fixed from a state in which an upward force is applied to the mold bottom plate by lift-up means from the state of FIG. FIG. 10 is a side configuration diagram showing a state where lift-up means is attached to the embedded formwork. FIG. 11 is a block diagram showing the construction process of the box culvert, and the embedded form laid between the side walls is in the state shown in FIG. FIG. 12 is a perspective configuration diagram of the box culvert. FIG. 13 is a side configuration diagram showing a state in which lift-up means is attached to a partial modification of an embedded formwork provided with an insert anchor. FIG. 14 is a perspective configuration diagram showing a state in which lift-up means (second example) is attached to the embedded formwork from the state of FIG. FIG. 15 is a front configuration diagram of the state of FIG. FIG. 16 is a side configuration diagram showing a state where lift-up means (second example) is attached to the embedded formwork. FIG. 17 is a perspective configuration diagram showing a state in which lift-up means (third example) is attached to the embedded formwork from the state of FIG. 5. FIG. 18 is a front configuration diagram of the state of FIG. FIG. 19 is a side configuration diagram showing a state in which lift-up means (third example) is attached to the embedded formwork. FIG. 20 is a front configuration diagram illustrating a state in which the upper rib member is temporarily fixed to a partial modification of the embedded formwork that does not have the lower rib member. FIG. 21 is a side configuration diagram showing a state in which lift-up means is attached to the partially modified example of FIG.

  Hereinafter, typical embodiments of the present invention will be described with reference to FIGS. The buried formwork according to this embodiment is constructed with cast-in-place concrete on the upper side thereof to constitute a floor slab of a structure such as an upper floor slab of a box culvert or a floor slab of a pier.

  In the example shown in the figure, an example is shown in which the upper floor slab D of the box culvert A is configured by such an embedded formwork. The box culvert A is a box-type embedded structure used as a road or a waterway. The box culvert A includes a bottom plate B, a side wall C, and an upper floor plate D (top plate). The bottom plate B is typically made of cast concrete. The side wall C is typically made of precast reinforced concrete (PCa). The upper floor slab D is installed between the left and right side walls C, C. Although illustration is omitted, one of the left and right side walls C, C may be a central wall that bisects the space in the box culvert A left and right.

  FIG. 12 shows an example of such a box culvert A. A plurality of box culverts A, A... Are connected to form the roads and waterways (the continuous direction of the roads is indicated by a symbol X in FIG. 12).

  The upper floor slab D includes an embedded mold 1 and a main body 2 formed of cast-in-place concrete that is driven into the embedded mold 1. At the same time, the embedded mold 1 includes a mold bottom plate 10 and a steel upper rib member 11 provided on the mold bottom plate 10.

  In the illustrated example, the mold bottom plate 10 is PCa having a lower surface portion 10c made of refractory concrete and an upper surface portion 10d made of ordinary concrete (see FIG. 10). Typically, when the thickness of the mold bottom plate is 150 mm, the lower surface portion 10c has a thickness of about 60 mm and the upper surface portion 10d has a thickness of about 90 mm. As the refractory concrete, typically, a material having a function of preventing explosion at the time of fire due to the organic fiber to be blended is used. The entire formwork bottom plate 10 may be made of refractory concrete.

  The mold bottom plate 10 has a rectangular plate shape having a length slightly shorter than the distance between the left and right side walls C. The formwork bottom plate 10 has its width direction W (also the width direction of the constructed upper floor slab / see FIG. 4) along the continuous direction X, and its length direction L (the length of the constructed upper floor slab). It is also installed between the left and right side walls C, C so as to be perpendicular to the continuous direction X. The mold bottom plate 10 includes a plurality of steel lower rib members 10a. Each of the lower rib members 10a, 10a,... Is made of a strip-shaped steel plate, the length direction thereof is along the length direction L of the mold bottom plate 10, and the plate surface is arranged vertically. A portion other than the upper edge portion 10 b protruding from the upper surface of the bottom plate 10 is embedded in the mold bottom plate 10, and is integrated with the mold bottom plate 10. That is, the lower rib member 10a is a buried metal object when the mold bottom plate 10 is manufactured. The plurality of lower rib members 10a, 10a,... Are arranged side by side with a space between the lower rib members 10a adjacent in the width direction W of the mold bottom plate 10. In addition, a plurality of connecting members 12, 12... Are fixed to each lower rib member 10a with a space between adjacent connecting members 12 in the length direction of the lower rib member 10a. Each connecting member 12 has a plate shape, and is fixed in a state where the plate surface thereof is in close contact with the plate surface of the lower rib member 10a on the lower end side (FIG. 10). Further, in the illustrated example, through holes 12 a are formed on the left and right of the upper end of each connecting member 12. The mold bottom plate 10 incorporates a desired number of desired reinforcing bars (not shown) such as reinforcing bars along the length direction L.

  In the illustrated example, the upper rib member 11 is made of angle steel. The upper rib member 11 is arranged such that one side of the bent portion 11a is vertically arranged and the length direction of the upper rib member 11 is along the length direction L of the mold bottom plate 10. It is integrated with the mold bottom plate 10 through the connecting material 12 protruding from the bottom. In the example shown in the figure, after connecting reinforcing bars (not shown) serving as distribution bars along the width direction W between adjacent connecting members 12 and 12 on each lower rib member 10a, each connecting member 12 is provided. The upper rib material 11 is integrally provided on each lower rib material 10a of the embedded mold 1 by bolting the upper end of the upper rib material 11 to the upper rib material 11 (FIG. 9).

  In the illustrated example, the box culvert A is constructed by the following procedure.

  First, the bottom plate B is constructed (FIG. 1). In the illustrated example, the bottom slab B is constructed by on-site concrete.

  Next, left and right side walls C and C are constructed on the bottom plate B (FIG. 2). In the illustrated example, the side wall C is constructed by standing a self-supporting PCa on the bottom plate B.

  Next, a desired number of brackets 3 protruding rightward are attached to the upper part of the left side wall C, and a desired number of brackets 3 protruding leftward are attached to the upper part of the right side wall C. Then, using the bracket 3 attached in this manner, the steel plate 4 having the length direction along the continuous direction X is horizontally supported on the upper part of the left side wall C and the upper part of the right side wall C, respectively. This is material 4 ′ (FIG. 3).

  Next, the embedded mold 1 is installed and supported between the left side wall C and the right side wall C using the beam material 4 '(FIG. 4).

  In this embodiment, the embedded mold 1 includes the left end portion of the lower rib member 10a, the left end portion of the upper rib member 11, the right end portion of the lower rib member 10a, and the upper rib member 11. The connecting member 12 'and the upper rib member 11 that are connected to the right end portion of the floor slab B are connected by a shaft body 5 having an axis line along the width direction W of the floor slab B and a shaft hole 6 through which the shaft member 5 passes. It has become.

  In the illustrated example, the through hole 12a of the connecting member 12 'and the corresponding through hole 11d of the upper rib member 11 function as the shaft hole 6, and the bolt 5' passed through the through holes 12a, 11d is the shaft. It functions as the body 5.

  With this configuration, in this embodiment, before the upper rib material 11 is permanently fixed to the mold bottom plate 10, the length direction of the mold bottom plate 10 using the left and right shaft bodies 5, 5 as fulcrums. The middle position can be lifted up (FIGS. 8 to 9), and the upper rib member 11 can be permanently fixed to the mold bottom plate 10 in such a lifted state. (FIG. 9), thereby, the tensile stress generated in the formwork bottom plate 10 when the cast-in-place concrete serving as the main portion 2 is placed is relieved.

  Specifically, first, the mold bottom plate 10 is installed (FIG. 4), and then the lower rib material 10a and the upper rib material 11 are temporarily fixed by the shaft body 5 and the shaft hole 6 (FIG. 5, FIG. 6). Next, the lift-up means 7 is installed between the middle position in the length direction of the upper rib member 11 and the middle position in the length direction of the mold bottom plate 10. An upward force is applied to the middle position in the length direction (FIGS. 8 to 9). Next, the upper ends of the plurality of connecting members 12, 12... Are bolted to the upper rib members 11, respectively, and the upper rib members 11 and the formwork bottom plate 10 are finally fixed (FIG. 9). Thereafter, the lift-up means 7 is removed, As described above, the reinforcing bars are placed and the cast-in-place concrete is placed to form the main body 2 (FIGS. 11 to 12).

  The example shown by FIGS. 1-12 has shown the example which comprised the lift-up means 7 including the jack 70. As shown in FIG. In the figure, reference numeral 70a is a movable part of the jack 70, and reference numeral 70b is a fixed part of the jack. In the illustrated example, the lower bar 71a and the upper bar 71b of the jig 71 composed of a lower bar 71a placed on the upper rib member 11, an upper bar 71b, and two bolt bodies 71c and 71c, The jack 70 is interposed between the two bolt bodies 71c and 71c so that the upward force is applied to the mold bottom plate 10 by the movement of the movable portion 70a of the jack 70. Yes. The two bolt bodies 71c, 71c are respectively passed from below through a through portion 10e provided on the mold bottom plate 10, and are inserted into the through portion 71b 'of the upper bar 71b through the through portion 71a' of the lower bar 71a. The upper end side is protruded upward, and a nut 71d is screwed to the protruding portion. The lower bar 71a has a length that is in contact with the plurality of upper rib members 11, 11.

  FIG. 13 shows an example in which the mold bottom plate 10 is provided with an insert anchor 10g as an embedded hardware at a position in the middle in the length direction. In the example shown in FIG. 13, the lower end side of the bolt body 71c passed through the passage portion 71a ′ of the lower bar 71a and the passage portion 71b ′ of the upper bar 71b is screwed to the insert anchor 10g. In the bolt body 71c, a nut 71d is screwed to a portion protruding upward from the upper bar 71b through the through portion 71b 'of the upper bar 71b. The remaining configuration in FIG. 13 is substantially the same as the example shown in FIGS.

  In the example shown in FIGS. 14 to 16, the lift-up means 7 is configured by an apparatus including a bar 72 a placed on the upper rib member 11 and two bolt bodies 72 b and 72 b. Each of the two bolt bodies 72b, 72b is passed from below through a through portion 10e provided on the mold bottom plate 10 and is inserted into the through portion 72a 'of the bar 72a so as to project the upper end side upward. The above-described upward force is applied to the mold bottom plate 10 by screwing the nut 72c screwed into the protruding portion. The bar 72a has a length that is simultaneously brought into contact with the plurality of upper rib members 11, 11,.

In the example shown in FIGS. 17 to 19, the lift-up means 7 is provided from below through a passage portion 10 e provided on the mold bottom plate 10, and is provided at a location 11 b that is horizontally disposed on the upper rib member 11. It was inserted through the through portion 11c and is constituted by a bolt member 73 to protrude the upper side upward, the upward force of the mold bottom plate 10 by causing screwed a nut 73a screwed on the projecting portion Is to be acted on. In the illustrated example, one bolt body 73 is linked to each upper rib member 11 as described above.

  The embedded rib 1 can be supported by the upper rib material 11 integrated with the built-in rib material 10a without requiring any special support work. Various rebars are arranged on the mold bottom plate 10, and the bottom mold 8 is arranged below the portion to be the haunch portion E, and cast-in-place concrete is cast above the buried mold 1 and directly above the side wall C. As a result, the upper floor slab D is formed and the joint between the upper floor slab D and the side wall C is formed (FIG. 11).

  After the curing, the bracket 3 and the steel plate 4 are removed, and a box culvert with a constant span is constructed in the continuous direction X (FIG. 12).

  20 and FIG. 21 show the length of the reinforcing bar 10f that is a part of the main reinforcing bar of the mold bottom plate 10, that is, the length of the mold bottom plate 10 without providing the mold bottom plate 10 with the lower rib member 10a. An example in which a part of the reinforcing bar 10f along the direction is connected to the upper rib member 11 by the connecting member 12 is shown. In the example shown in FIGS. 20 and 21, the lower ends of the connecting members 12 are welded to the reinforcing bars 10f. 20 and FIG. 21, the left end of the reinforcing bar 10f and the left end of the upper rib member 11 and the right end of the reinforcing bar 10f and the right end of the upper rib member 11 are connected. The connecting member 12 ′ and the upper rib member 11 are connected by a shaft body 5 ′ having an axis line along the width direction of the upper floor slab D and a shaft hole 6 through which the shaft member 5 ′ passes. Also in this case, before the upper rib material 11 is permanently fixed to the mold bottom plate 10, the upper end of the mold bottom plate 10 can be lifted upward using the left and right shaft bodies 5 ′ as fulcrums. In addition, the upper rib member 11 can be permanently fixed to the mold bottom plate 10 in the lifted-up state as described above, and the tensile stress generated in the mold bottom plate 10 at the time of placing the cast-in-place concrete can be thereby reduced. It can be mitigated. 20 and 21 are substantially the same as the examples shown in FIGS. 1 to 12, and the description thereof is omitted.

  Of course, the present invention is not limited to the embodiments described above, but includes all embodiments that can achieve the object of the present invention.

DESCRIPTION OF SYMBOLS 1 Embedded form 10 Mold form bottom plate 10a Lower rib material 11 Upper rib material 12 Connecting material 5 Shaft body 6 Shaft hole

Claims (3)

It is an embedded formwork which is casted with cast-in-place concrete on the upper side and constitutes a floor slab,
A formwork bottom plate made of precast reinforced concrete, which is integrally provided with a steel lower rib material arranged along the length direction of the floor slab, as an embedded metal;
An upper rib member made of steel provided along the length direction on the mold bottom plate;
A plurality of connecting members for connecting the lower rib member and the upper rib member;
Among the plurality of connecting materials, the connecting material and the upper side connecting the left end portion of the lower rib member, the left end portion of the upper rib member, and the right end portion of the lower rib member and the right end portion of the upper rib member. The rib member can be temporarily fixed by a shaft body having an axis line along the width direction of the floor slab and a shaft hole through which the shaft member passes,
Among the plurality of connecting members, a connecting member other than the connecting member connecting the left end portion of the lower rib member and the left end portion of the upper rib member and the right end portion of the lower rib member and the right end portion of the upper rib member. An embedded mold for floor slabs , in which a material and the upper rib material can be permanently fixed from the temporarily fixed state while an upward force is applied to a position in the middle in the length direction of the mold bottom plate with the shaft body as a fulcrum. frame. It is an embedded formwork which is casted with cast-in-place concrete on the upper side and constitutes a floor slab,
Formwork bottom plate made of precast reinforced concrete,
An upper rib member made of steel provided along the length direction on the mold bottom plate;
A plurality of connecting members that connect the reinforcing bars that are part of the main reinforcing bars of the mold bottom plate and the upper rib material;
Among the plurality of connecting members, the connecting member that connects the left end portion of the reinforcing bar and the left end portion of the upper rib member and the right end portion of the reinforcing bar and the right end portion of the upper rib member, and the upper rib member, With the shaft body along the axis in the width direction of the floor slab and the shaft hole through which it can be temporarily fixed ,
Among the plurality of connecting members, the connecting member other than the connecting member that connects the left end portion of the reinforcing bar, the left end portion of the upper rib member, the right end portion of the reinforcing bar, and the right end portion of the upper rib member, and the upper portion. An embedded formwork for floor slabs that can be fixed to a rib material while applying an upward force to a position in the middle of the mold bottom plate from the temporarily fixed state with the shaft body as a fulcrum .
Embedded formwork for floor slabs.   The embedded formwork for floor slabs according to claim 1 or 2, wherein the mold bottom plate is provided with an insert anchor at a position in the middle of the length direction.

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