JP2005016078A - Cast-in-place hollow concrete slab, its construction method and spacer-cum-support used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a further improved cast-in-place hollow concrete slab capable of reducing the construction man-hour in a site, lessening the number of components and also facilitating the construction. <P>SOLUTION: A spacer and a support 30 equipped with an insertion body 32 into a buried material 20 between the upper surface of the buried material 20 and the upper end bar 14 is made to intervene. The insertion body 32 of the spacer and the support 30 is inserted in the buried material 20 to become a state to prevent the free movement in the horizontal direction, and uplift movement can be also controlled by the spacer and the support 30 to easily position the cast-in-place hollow concrete slab to a predetermined position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cast-in-place hollow concrete slab, a construction method thereof, and a spacer / support used therefor.
[0002]
[Prior art]
The cast-in-place hollow concrete slab has a formwork built at the construction site, and after placing the bottom reinforcement, embedding material, top reinforcement, etc., cast the cast-in-place concrete and wait for the concrete to harden. Built by removing the formwork. This construction method involves manufacturing a hollow concrete board with pre-cast concrete board (PC board) and embedding material and necessary reinforcements in the factory, bringing it into the construction site and installing it between the spans of the frame. Along with the construction method of hollow concrete slabs in which cast concrete is cast, it is widely used when building apartment houses and the like. The construction method using precast concrete plates involves lifting heavy precast concrete plates to the required number of floors at the construction site and installing them at predetermined positions between spans. I need. On the other hand, all cast-in-place hollow concrete slabs are construction sites and have the advantage of not requiring large cranes.
[0003]
In the construction of the cast-in-place hollow concrete slab, buoyancy is generated in the embedding material, which is a lightweight body, due to the casting of the cast-in-place concrete, so that it can be lifted or moved in an indefinite direction. Therefore, it is necessary to regulate the free movement of the embedding material.
[0004]
In Patent Document 1 (Japanese Patent Publication No. 64-9427), after placing a lower end bar on a formwork, an embedding material holder is attached to the formwork, and the embedding material is attached by the embedding material holder. Positioning and fixing in a state of floating from the bottom bar, placing an appropriate spacer on the fixed implant, placing the top bar there, and then placing the cast-in-place concrete A method is described. In this construction method, the free movement of the embedding material is regulated by the embedding material holder attached to the mold.
[0005]
In Patent Document 2 (Japanese Patent Laid-Open No. 9-250196), an embedding material, which is a lightweight body, is arranged in a small space partitioned in a grid pattern by upper and lower ends arranged vertically and horizontally, and In order to prevent the embedding material from being lifted by the concrete to be placed (so that the free movement of the embedding material can be restricted), the bottom surface side of the embedding material is fitted into an auxiliary muscle arranged on the lower end muscle side, A construction method is described in which a cast-in-place concrete is placed after a suspension member is disposed between the embedding material and the upper end reinforcement. Further, in Patent Document 3 (Japanese Patent Laid-Open No. 2002-266457), in a similar construction method, a latching tool provided with a latching recess for latching an auxiliary muscle is attached to an embedded material. A construction method is described in which the embedding material is prevented from floating and rotating simultaneously by being hooked to an auxiliary muscle attached to the upper end muscle.
[0006]
[Patent Document 1] Japanese Patent Publication No. 64-9427 [Patent Document 2] Japanese Patent Application Laid-Open No. 9-250196 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-266457
[Problems to be solved by the invention]
In the construction method described in Patent Document 1 (Japanese Patent Publication No. 64-9427), the free movement of the embedding material is regulated by the embedding material holder attached to the mold, and the distance from the upper end bar is also controlled by the spacer. Since it can be surely secured, a stable hollow concrete slab can be constructed. However, a lot of on-site work is required, such as an operation for attaching the embedding material holder to the mold and an operation for fixing the embedding material to the attached embedding material holder.
[0008]
The construction method described in Patent Document 2 (Japanese Patent Laid-Open No. 9-250196) and Patent Document 3 (Japanese Patent Laid-Open No. 2002-266457) is necessary for the work of arranging auxiliary bars in addition to the upper and lower bars. In addition, the field work is not only complicated, but also a hanging member (Patent Document 2) and a latching tool (Patent Document 3) provided with a latching recess are used as the embedded material. There is a need. Furthermore, in this construction mode, the size of one embedding material is small, and a lot of time and labor are required for the work of sequentially embedding a large number of small embedding materials in the grid. In addition, since it is necessary to ensure good wraparound of the cast-in-place concrete, the interval between the embedding material and the embedding material cannot be made very narrow, and as a result, there is a disadvantage that a high hollow ratio cannot be ensured.
[0009]
The present invention has been made in view of the circumstances as described above, and can be reduced on-site construction man-hours, the number of parts is small, construction is easy, and a high hollow ratio can be ensured. An object of the present invention is to provide a cast-in-place hollow concrete slab, a construction method thereof, and a spacer / support used therefor.
[0010]
[Means for Solving the Problems]
The cast-in-place hollow concrete slab according to the present invention is a cast-in-place hollow concrete slab constructed by placing cast-in-place concrete with at least the bottom reinforcement, the embedded material, and the top reinforcement placed on the formwork at the construction site. A spacer / support having an insert to the implant is interposed between the upper surface and the upper end of the implant, and the insert of the spacer / support is inserted in the implant. And lifting is restricted by the spacer / support.
[0011]
Further, the present invention provides a method for constructing the above-mentioned cast-in-place hollow concrete slab by embedding a spacer and a support tool including an insert to the embedded material between the upper surface and the upper end of the embedded material. It is inserted in the material, so that even if buoyancy is caused by cast-in-place concrete, the floating of the embedded material is restricted, and relative movement between the spacer and the support is not caused. Later, a method for constructing a cast-in-place hollow concrete slab characterized by casting a cast-in-place concrete is also disclosed.
[0012]
In the in-situ hollow concrete slab and the construction method thereof according to the present invention, the insertion member of the spacer / support is inserted into the embedding material, and the two are integrated so as not to move relative to each other. On the other hand, it is interposed in a state in which the floating of the embedding material is regulated. Therefore, in the present invention, a special member such as an “embedding material holder” is not used as in the method of Patent Document 1, and “auxiliary reinforcement” is not used as in the methods of Patent Documents 2 and 3. It is possible to effectively prevent the embedding material from unexpectedly moving due to concrete placement without separately arranging the bars.
[0013]
A spacer having a flat lower end surface is disposed between the embedding material and the upper streak by a conventional method. In the present invention, instead of such a spacer, the embedding material is disposed on the lower surface. The intended purpose described above can be achieved only by using a spacer / support provided with an insertion body, so that a significant labor saving of the entire construction method can be achieved. In addition, the size of the embedding material to be used is not restricted by the arrangement form of the upper end reinforcement as in References 2 and 3, so that an arbitrary size of the embedding material is placed between the lower end reinforcement and the upper end reinforcement. It is possible to arrange them in a large space, and the hollow ratio of the concrete slab as a whole can be increased.
[0014]
Preferably, two or more upper end bars are arranged on the upper surface side of the embedding material, and at least two or more spacers that are not supported by the same reinforcing bar between the upper surface and the upper end muscle of the embedding material A cum support is to be interposed. In this aspect, when buoyancy occurs in the embedded material due to the placement of cast-in-place concrete, it is possible to more reliably prevent the embedded material from moving irregularly or rotating in the horizontal direction. After the concrete is hardened, the embedding material is securely embedded in a preset position. Therefore, it is possible to reliably obtain a cast-in-place hollow concrete slab having rigidity and hollowness as designed.
[0015]
In the construction method of the present invention, the cast-in-place concrete is placed with a spacer / support interposed between the upper end bars so that the embedding material does not lift even when receiving the buoyancy of the cast-in-place concrete. However, when receiving the buoyancy of cast-in-place concrete, the embedding material is lifted by a predetermined distance, and after that, a spacer and support tool are interposed between the upper end bars so that the embedding material is positioned at that position. The cast-in-place concrete may be placed in a state in which it is left.
[0016]
In the former case, it is necessary to support the embedding material in advance with respect to the upper end muscle so that a predetermined distance can be taken between the lower end muscle, and for that purpose, the upper end as a spacer and support tool is required. It is desirable to use one provided with a hanger for the muscle. In the latter case, a part of the spacer / support is engaged with the upper end muscle in the posture before the embedding material is lifted so that the free movement of the embedding material in the horizontal direction is restricted. It is desirable to use a spacer / support that allows the embedding material, that is, the spacer / support, to rise while maintaining the above.
[0017]
A more preferred embodiment of the construction method according to the present invention is as follows. First, an appropriate spacer is placed on the built-in formwork, the lower end bar is laid out using the spacer, and the lower end line and the formwork are partially fixed by an appropriate fastener. The spacer secures a desired distance between the lower surface of the slab and the bottom bar. Thereafter, a desired embedding material is arranged, and upper end bars are temporarily arranged so that at least two reinforcing bars are positioned on the upper surface side of the arranged embedding material.
[0018]
Next, the upper end muscle is lifted and set to a required height using an appropriate spacer, and the lower end muscle and the upper end muscle are fastened with a fastening tool. After that state, the spacer / support described above is attached between the upper end muscle and the surface of the embedding material while inserting the insert into the embedding material. As a result, the embedding material does not move irregularly in the horizontal plane, and depending on the form of the spacer / support, the embedding material is suspended from the upper end line or is placed on the lower end line. However, the movement other than the upward movement is restricted by the engagement between the upper end muscle and the upper end muscle contact body of the spacer / supporting tool. After that, cast in place concrete. After the concrete is hardened, the formwork is removed to complete the concrete slab according to the present invention.
[0019]
In the above construction method, in addition to the appropriate positioning of the embedding material as described above, it is also effectively prevented that the upper end muscle is displaced due to the buoyancy acting on the embedding material. In other words, the upper end muscle and the lower end muscle are partly fastened with an appropriate binding tool, and the lower end part of the state is partly fixed to the mold, so that the upper part of the upper part is caused by the buoyancy acting on the embedding material. The force to lift is effectively suppressed by the formwork.
[0020]
The present invention, as a spacer and support used in the construction method of the above-mentioned in-situ hollow concrete slab, a substrate that comes into contact with the surface of the embedded material, and an insert into the embedded material that is erected on the back surface of the substrate, Disclosed is a spacer / support that includes at least an upper muscle abutment attached to an upper surface of a substrate. You may make it equip an upper end muscle contact body with the suspending tool to an upper end muscle. The spacer / support for slab may be made of metal or a resin product such as polyethylene or polypropylene. You may make it provide the return | turnback in order to prevent omission in the insertion body to an embedding material.
[0021]
In the present invention, the embedding material is preferably a synthetic resin foam such as expanded polystyrene. However, if the specific gravity is smaller than the concrete cast on the spot, a known lightweight embedding material can be used. it can. The shape and size of the embedding material can be selected as appropriate according to the design conditions of the concrete slab to be constructed, provided that the above conditions are satisfied. It is preferable that at least the corner portion on the back surface side of the embedded body has a rounded shape so that it can go around. The shape in plan view is usually rectangular, but is not limited to this.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments. FIG. 1 is a perspective view showing a state in the middle of construction of a cast-in-place hollow concrete slab according to the present invention, and FIG. 2 is a side view showing a part thereof as seen from the direction of the arrow in FIG. FIG. 3 shows the spacer and support used there.
[0023]
In the construction of the on-site hollow concrete slab, first, a concrete casting mold 10 is made of plywood or the like. The lower end bars 12 are arranged vertically and horizontally through appropriate spacers 11 thereon. The spacer 11 ensures a certain distance between the mold 10 and the bottom stripe 12. Then, it fixes to the formwork 10 using the suitable fastener 13 so that the lower end reinforcement 12 cannot move upwards.
[0024]
A plurality of embedding materials 20 are arranged on the fixed lower end streak 12 while maintaining a required interval. Although the embedding material 20 has a rectangular shape in the illustrated example, the embedding material 20 may have any conventionally known shape used in hollow concrete slabs. The size of the embedding material 20 in a plan view is also arbitrary, and may be an appropriate size in consideration of workability. As an example, a rectangular parallelepiped shape such as 400 mm × 400 mm × 130 m may be used, and a rectangular parallelepiped shape having a size such as 400 mm × 1200 mm × 130 m may be used.
[0025]
The embedding material 20 is preferably a foamed resin molded body such as polystyrene foam, but if it is lighter than the concrete to be cast, it is foamed like a hollow non-foamed resin molded body or a hollow metal molded body. A material other than resin may be used. In addition, it is preferable that at least the corner portion on the back side be rounded. As a result, the cast-in-place concrete cast into the back surface of the embedding material 20 easily enters, and the construction is facilitated.
[0026]
The upper end stripes 14 are temporarily placed vertically and horizontally on each of the placed implants 20. The spacing between the lower reinforcing bars 12 and the upper reinforcing bars 14 is set in consideration of the strength of the structure required for the hollow concrete slab, but usually two or more upper ends on the upper surface side of the embedding material 20. The muscle 14 is positioned. In the example shown in FIG. 1, three vertical and horizontal upper streaks 14 are located on the upper surface of one embedding material 20. The temporarily placed upper streak is lifted to a predetermined height by using an appropriate upper streak spacer 15, and is vertically moved at a plurality of locations with a predetermined interval between the lifted upper streak 14 and the lower end rebar 12. The muscle tying tool 16 is attached. Accordingly, the upper end stripe 14 and the lower end stripe 12 are not freely separated in the vertical direction.
[0027]
Next, or in parallel with the lifting operation of the upper end bars, the spacer / supporting tool 30 having the shape shown in FIG. 3 is fixed to the upper surface of the embedding material 20 temporarily placed on the lower end bars 12. The spacer / support 30 has a substrate 31, and a plurality of inserts 32 are formed on the back surface of the substrate 31. The insertion body 32 is inserted into the embedding material 20 and has a barb 33 for retaining it in part. On the upper surface of the substrate 31, an upper end muscle contact body 34 is integrally formed. The return 33 may be omitted.
[0028]
The upper end muscle abutting body 34 has a required rigidity, and has a concave portion 35 of a size that allows the upper end muscle 14 to enter the upper end. Further, one end of a fastening belt 36 as a means for gripping the upper end muscle 14 is fastened to the lower side of the concave portion 35, and the other end of the fastening belt 36 is fastened to the upper side of the concave portion 35. A locking groove 37 is formed. In the illustrated example, the fastening belt 36 is made of spring steel, and the bent portion at the tip thereof is fitted into the locking groove 37. However, the means for gripping the upper end muscle 14 is not limited to this. Any means may be used.
[0029]
The number and position of the spacers / supports 30 to be fixed to one embedding material 20 are arbitrary, but as shown in FIG. 1, at least two spacers that are not supported by the same reinforcing bar constituting the upper end bar 14 It is desirable to fix the cum supports 30a and 30b to one embedding material 20. After fixing the required number of spacers / supports 30, the embedding material 20 is lifted, and the upper end bars 14 are inserted into the recesses 35 formed at the upper end of the upper end bar abutting body 34, and fixed by the fastening belt 36. Thereby, the embedding material 20 is fixed in a space suspended from the upper end muscle 14 in the space between the upper end muscle 14 and the lower end muscle 12. The spacer / support 30 can be made of metal or synthetic resin on condition that it has a required strength.
[0030]
Next, cast in-place concrete. By placing concrete, buoyancy is generated in the embedding material 20, and the upper material tries to move upward. However, the movement is blocked by the tension of the upper end muscle abutting body 34 formed on the spacer / support 30. Further, since the insertion body 32 is inserted into the implant member 20, even if buoyancy is applied, the position and posture of the implant body 20 do not change. Therefore, even after placing the cast-in-place concrete, all the embedding materials 20 are stopped at the initial position, and a hollow concrete slab as designed is constructed.
[0031]
Due to the buoyancy acting on the embedding material 20, the upper end streak 14 tends to rise. However, the upper end bar 14 is connected to the lower end bar 12 by the upper and lower bar binding bracket 16, and the lower end bar 12 is connected to the mold 10 by the fastener 13. Therefore, even if an upward force is applied to the upper end muscle 14 via the embedding material 20, no positional deviation occurs.
[0032]
FIG. 4 shows another form of spacer / support. This spacer / support 30B has a recess 35b in which the upper end stripe 14 can be put on the upper end central portion of the upper end abutment body 34, and flanges 34b, 34b extending in the horizontal direction are formed on both sides thereof. A cut groove 34c having a bowl shape is formed in the flange 34b. In FIG. 4, 36b is a U-shaped fastener used together with the spacer / support tool 30B, and the lower ends of the left and right leg portions thereof are a locking portion 37b bent horizontally. The upper end bar 14 is brought into contact with the concave portion 35b of the spacer / support 30B, and the fastener 36b is lowered from above so that the locking portion 37b passes through the cut groove 34c. When the locking portion 37b reaches the back surface of the flange 34b, the locking portion 37b is pulled toward the left front side in the drawing. As a result, the locking portion 37b of the fastener 36b is supported on the back surface of the flange 34b, and the spacer / supporting tool 30B (and the embedding material 20) is suspended from the upper end muscle 14 as shown in FIG. It will be in a lowered state.
[0033]
FIG. 5 shows still another embodiment of the spacer / support. The spacer / support tool 30 </ b> C includes a concave groove 38 having a size that allows the upper end muscle 14 to enter the upper end muscle contact body 34. The length of the upper end muscle abutting body 34 is such that the recessed groove 38 formed in the upper end muscle abutting body 34 of the spacer / supporting tool 30C fixed to the embedding material 20 on the lower end muscle 12 is placed. The length is such that the upper end streak 14 enters the upper end portion. Further, the depth of the concave groove 38 in the vertical direction can ensure a required distance between the upper surface of the embedding material 20 and the upper end stripe 14 in a state where the upper end stripe 14 is in contact with the bottom 39 of the concave groove 38. It is said to be deep. In the example shown in the figure, the spacer / support 30C has the two upper end abutment members 34, but there may be one.
[0034]
FIG. 6 is a view corresponding to FIG. 2 for explaining a state in which the on-site hollow concrete slab is constructed using the spacer / support 30C shown in FIG. Similar to the case shown in FIGS. 1 and 2, the lower end bars 12 are arranged vertically and horizontally on the formwork 10, and a plurality of embedding materials 20 are provided on the lower end bars 12 while maintaining a predetermined interval. Temporarily placed. The spacer / supporting tool 30 </ b> C is fixed to the implant 20 while the insert 32 is inserted into the upper surface of the temporarily placed implant 20. In parallel with the operation, the upper end stripes 14 are temporarily placed vertically and horizontally. At that time, while the upper end bars 14 enter the recessed grooves 38 formed in the upper end bar contact body 34 of the spacer / support 30C, as shown in FIG. Temporary placement is performed so that the upper end stripes 14 or more are located. Next, in the same manner as in FIGS. 1 and 2, the temporarily placed upper bar 14 is raised to a predetermined height using an appropriate upper bar spacer 15.
[0035]
In this state, cast-in-place concrete is placed. By placing concrete, buoyancy is generated in the embedding material 20 and it floats. The embedding material 20 rises until the bottom 39 of the concave groove 38 formed in the upper end muscle abutting body 34 of the spacer / support 30C comes into contact with the upper end muscle 14, and stops there (indicated by a virtual line in FIG. 6). . The position is a predetermined position of the embedding material 20 in the hollow concrete slab, and the embedding material 20 is located at a predetermined distance from both the lower end bars 12 and the upper end bars 14. Also in this case, the spacer / support tool 30C rises while being regulated by the concave groove 38, and the embedding material 20 is integrated with the spacer / support tool 30C by inserting the insert 32. Therefore, the embedding material 20 does not rotate in the horizontal direction in the process of lifting, and the embedding material 20 is lifted while maintaining the posture of this place, and each of the embedding materials 20 after being lifted is positioned in the intended place. Is done.
[0036]
【The invention's effect】
As described above, in the present invention, the spacer / supporting tool is provided with an insertion body to the implant material between the upper end muscle and the implant material and also has a function of suppressing the upward movement of the implant material. By interposing, it is possible to reduce the number of on-site construction man-hours, to reduce the number of parts, to facilitate construction, and to obtain a more improved on-site hollow concrete slab that can secure a high hollow ratio. .
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state in the middle of construction of a cast-in-place hollow concrete slab according to the present invention.
FIG. 2 is a side view showing a part of a cast-in-place hollow concrete slab according to the present invention as seen from the direction of the arrow in FIG.
FIG. 3 is a view showing an example of a spacer / support used.
FIG. 4 is a view showing another example of the spacer / support used.
FIG. 5 is a view showing still another example of the spacer / support used.
6 is a view corresponding to FIG. 2 showing a hollow concrete slab constructed using the spacer / support shown in FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Formwork, 11 ... Spacer, 12 ... Lower end bar, 13 ... Lower end bar clamp, 14 ... Upper end bar, 15 ... Upper end bar spacer, 16 ... Upper and lower barb fastener, 20 ... Implant, 30, 30B, 30C: spacer / support, 31 ... substrate, 32 ... insert, 33 ... return, 34 ... upper end abutment body, 35 ... recessed, 36 ... retaining belt, 37 ... locking groove, 38 ... recessed groove

Claims (8)

A cast-in-place hollow concrete slab constructed by placing cast-in-place concrete with at least the bottom reinforcement, the embedded material, and the top reinforcement placed on the formwork at the construction site, A spacer / support having an insert to the embedded material is interposed between the upper end bars, and the embedded material is inserted into the insert of the spacer / support and is lifted by the spacer / support. A cast-in-place hollow concrete slab characterized by regulation. Two or more upper end bars are located on the upper surface side of the embedding material, and at least two spacers / supports that are not supported by the same reinforcing bar are provided between the upper surface and the upper end of the embedding material. The hollow concrete slab according to claim 1, wherein the hollow concrete slab is interposed. A method for constructing a cast-in-place hollow concrete slab constructed by placing cast-in-place concrete with at least a bottom reinforcement, an embedded material, and a top-up reinforcement arranged on a formwork at a construction site, A spacer / support with an insert to the embedding material is interposed between the upper surface and the upper end of the insert with the insert inserted into the embedding material, so that the buoyancy by the cast-in-place concrete acts. However, the floating of the embedding material is restricted, and the cast-in-place hollow concrete slab is characterized by placing the cast-in-place concrete after the relative movement between the spacer and the support is prevented. Construction method. Two or more upper end bars are positioned on the upper surface side of the embedding material, and at least two spacers / supports that are not supported by the same reinforcing bar are interposed between the upper surface and the upper end of the embedding material. The construction method of a spot cast hollow concrete slab according to claim 3, wherein spot cast concrete is cast as a state. 5. The site according to claim 3 or 4, wherein the site-cast concrete is placed in a state where a spacer and a support are interposed so that the embedding material does not lift even when receiving the buoyancy of the site-cast concrete. Construction method for hollow concrete slabs. When receiving the buoyancy of cast-in-place concrete, the embedding material floats up a predetermined distance, and then the cast-in-place concrete is placed with spacers and supports interposed so that the embedding material can be positioned. The construction method of the in-situ hollow concrete slab according to claim 3 or 4. A spacer for a hollow concrete slab characterized by comprising at least a substrate that comes into contact with the surface of the embedding material, an insert into the embedding material that is erected on the back surface of the substrate, and a top muscle abutment that is attached to the upper surface of the substrate Support tool. The spacer / support for hollow concrete slabs according to claim 7, wherein the upper end muscle abutting body includes a hanging tool for the upper end muscle.

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