JP2014095282A - Large span concrete slab form and construction method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large span concrete slab form and a construction method using the same capable of omitting a falsework and expediting construction work through a structure which does not cause a fire resistance issue.SOLUTION: A bottom form plate 11 with steel rib materials 12 preliminarily fixed thereto is installed between a road side wall 1a and a central wall 1b without using an extensive falsework. A plurality of lower reinforcing bars 3a extended in a direction orthogonal to a span direction are inserted into each slit 13 on the steel rib material 12 with a space between the reinforcing bars 3a arranged in accordance with bar arrangement design. Other lower reinforcing bars 3b extended in the span direction are arranged on the lower reinforcing bars 3a and fixed thereto with binding wires. After arranging upper reinforcing bars 4a and 4b, concrete 7 is placed and cured. Fire-resistance performance is satisfied not by the bottom form plate 11 alone but by a reinforced concrete slab.

Description

  The present invention is, for example, a large-span concrete floor slab form that can be used when constructing a large-span concrete floor slab with a large slab thickness above a large underground space or semi-underground large space, and a large size using the form slab. The present invention relates to a method for constructing a span reinforced concrete slab.

  When building a concrete floor slab with a large slab thickness of 500 to 1000 mm, for example, on the upper part of a digging road or large underground / semi-underground space, the formwork should be supported by a large support that can withstand the concrete loading load. It is common.

  However, it takes a long period of time to install a large support work under the floor slab to be built, and the cost of the support work including installation work becomes enormous. Work in space is severely limited.

  In addition, the large-span structure has a large inside sky, and a scaffold for the installation and dismantling of support works becomes a major factor.

  On the other hand, for example, using a steel concrete composite slab having a bottom steel plate described in Patent Documents 1 and 2 and the like, it is conceivable to construct a large-span floor slab without supporting work.

Japanese Patent No. 3119169 JP 2008-144459 A

  As described above, the composite floor slab has the advantage that support work can be omitted and rapid construction is possible. However, in a structure in which fire resistance is a problem, the use of a steel-concrete composite floor slab in which the steel plate is exposed on the lower surface of the floor slab is limited in terms of fire resistance.

  The present invention is intended to solve the above-described problems, and a large-span concrete floor slab form and a floor slab form that enables rapid construction and omission of support work in a structure in which fire resistance is not a problem. The purpose is to provide the construction method used.

  The floor slab form of the present invention is a large-span concrete floor slab form for placing a reinforced concrete floor slab on a support structure such as a column or wall, and the form bottom plate and the form bottom plate A plurality of steel rib members that are parallel to each other and have a cross-sectional rigidity that can withstand the load during concrete placement, and can be used to place the reinforcing bars that are placed on the concrete floor slabs on the steel rib material web A plurality of are formed.

  The constructed floor slab is designed as a reinforced concrete floor slab with the required cross-sectional composition and strength, and the reinforcement of the reinforcing bar is designed.

  The steel rib material arranged in parallel on the formwork bottom plate only needs to have a cross-sectional rigidity that can withstand the load when placing concrete. preferable.

  The material of the mold bottom plate is not particularly limited, but a steel plate is preferable in that a steel rib material can be welded or bolted.

  Or you may use a precast concrete board (henceforth PCa version) for a formwork baseplate. Here, the PCa plate is, for example, a reinforced concrete plate, a steel reinforced concrete plate, a prestressed concrete plate, an ultrahigh strength fiber reinforced concrete plate, or the like. When the PCa plate is used for the formwork bottom plate, a steel rib material may be provided in the PCa plate in advance (see FIG. 5 (a)).

  In this case, the PCa plate can be used as a discarded formwork, and the thickness of the PCa plate can be used as a load-resistant coating (a part of the fog necessary for ensuring load-bearing performance).

  Moreover, when using a steel-frame reinforced concrete board for a formwork bottom plate, as shown in FIG. 6, a plurality of holes are provided in the reinforcing steel material and the lower rib material, and the reinforcing bars are installed so as to penetrate the holes. Since the holes provided in the reinforcing steel material and the lower rib material act as stoppers, it is possible to integrate the concrete and the steel material of the mold bottom plate.

  When placing concrete in the main body, the load acts in the direction of pulling out the lower rib material from the formwork bottom plate, but by providing a reinforcing steel material and a reinforcing bar that penetrates the lower rib material. Thus, it is possible to efficiently resist the pulling load.

  From the viewpoint of securing the cross-sectional rigidity that can withstand the load during concrete placement by the steel rib material, it is also conceivable to provide the steel rib material under the formwork bottom plate, not the floor slab side, In that case, the inner space cross section is affected, so there is a problem that the use space is reduced, and even if it is attempted to overcome this defect by removing the steel rib material, the removal is difficult due to the work at a high place. is there.

  Therefore, in the present invention, the steel rib material is dared to be buried, in addition to the function of stiffening the formwork to withstand the load at the time of placing concrete, the reinforcing bars arranged in the reinforced concrete floor slab, mainly the bottom reinforcement Therefore, a slit is provided at a position corresponding to the required cover thickness from the lower surface of the reinforced concrete floor slab.

  As described above, the floor slab form of the present invention, including the steel rib material, can be used as it is without removing the mold, but it is not expected to have fire resistance. It will be designed to meet the fire resistance required for reinforced concrete floor slabs by securing the reinforcing bars.

  In this case, since the reinforcing bars are laid between the slits, it will be difficult to place the slits, especially in the horizontal direction. It is preferable to have a long slot-like slit shape. If it is a long groove-like slit shape, it is possible to insert the reinforcing bars from an oblique state, or to insert a plurality of reinforcing bars together and then move them horizontally so as to obtain an appropriate interval.

  Thus, a reinforced concrete slab can be constructed by arranging one or more reinforcing bars arranged in the direction perpendicular to the support span of the concrete slab and placing concrete.

  The steel rib material can be divided into two parts: a lower rib material and an upper rib material that can be attached to and detached from the lower rib material via a connecting member.

  In this case, the lower rib member can secure a cross-sectional rigidity sufficient to support the load acting before placing the concrete in a state where the lower rib member is arranged in parallel on the mold bottom plate. In other words, even if it is not enough to support the load when placing concrete in that state, the worker can support the load acting before placing the concrete, such as performing reinforcement work on the formwork bottom plate. To do.

  After that, the reinforcing ribs placed on the concrete floor slab are placed on the upper end of the lower rib member, and the upper rib member is connected to the lower rib member via a connecting member. The cross-sectional rigidity should be sufficient to withstand this load.

  In this case, the reinforcing bars to be arranged on the floor slab may be placed on the upper end portion of the lower rib member, so that the reinforcing work is further facilitated as compared with the case where the reinforcing bars are inserted into the slits described above.

  The form and connection method of the connecting member are not particularly limited, but if a splice plate and a high-strength bolt are used, it is relatively easy to ensure rigidity in a state where the lower rib member and the upper rib member are connected.

  In this way, the upper rib member is installed in an unconnected state, and a plurality of reinforcing bars arranged in the direction perpendicular to the support span of the concrete floor slab are placed on the lower rib member, and the connecting member is used. After connecting the upper rib material to the lower rib material, the concrete reinforced concrete slab can be constructed by placing concrete.

  In the case of a composite floor slab in which the bottom steel plate constitutes a part of the floor slab as a structural member, there is a problem of fire resistance, whereas in the present invention, a reinforced concrete floor slab structure reinforced by a reinforcing bar that secures the necessary cover thickness Therefore, the problem of fire resistance can be cleared.

  By receiving the concrete casting pressure with the cross-sectional rigidity of multiple steel rib members arranged in parallel on the formwork bottom plate, large span construction is possible without requiring extensive support work, especially rapid construction. Useful under the required conditions. In addition, since the inner cross section is not eroded by the support work or the like, the work on the inner cross section can be performed in parallel.

  Reinforcing work is easy because the reinforcing bars placed on the concrete slab are received by the slits formed in the steel rib material.

  If the steel rib material is divided into a lower rib material and an upper rib material, and the upper rib material is made detachable by a connecting member, the bar arrangement work is further facilitated.

  When the formwork bottom plate is a PCa plate, the formwork bottom plate can be used as a discarded frame and load-resistant coating (a part of the fog necessary for ensuring load-proof performance).

  In addition, when the PCa plate of the mold bottom plate is a steel reinforced concrete plate and a plurality of holes are provided in the reinforcing steel material and the lower rib, and a reinforcing bar penetrating both holes is installed, the holes provided in the reinforcing steel material and the lower rib are Acts as a detent and can integrate concrete and steel.

  When placing concrete in the main body, the load acts so as to pull out the lower rib from the bottom plate of the formwork, but by placing reinforcing bars that penetrate both the reinforcing steel and the lower rib, it is efficient against this pull-out load. Can resist.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention, where (a) is a plan view, (b) is a sectional view taken along line AA in (a), and (c) is a sectional view taken along line BB in (a). . (a) is the figure which expanded and showed a part of FIG.1 (b), (b) is the enlarged view of FIG.1 (c). It is the vertical sectional view which showed other embodiment of this invention. (a)-(d) is an expanded sectional view which shows the construction procedure in embodiment of FIG. It is one Embodiment at the time of using PCa plate for the formwork baseplate in this invention, and is the schematic perspective view which showed the time of laying the panel. FIG. 6 is a schematic perspective view showing the next procedure of the embodiment of FIG. 5 and showing the time when the bars are arranged below the floor slab. FIG. 7 is a schematic perspective view showing the next procedure of the embodiment of FIG. 6 and showing the time when the upper rib member is joined. In the present invention, an embodiment in which a steel frame reinforced concrete plate is used as a mold bottom plate is shown. (A) and (b) are cross-sectional views, and (c) is a reinforcing steel material, a reinforcing bar, and a lower rib material. It is the shown schematic perspective view.

  Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 and FIG. 2 show a floor slab for constructing a large span reinforced concrete floor slab having a span of about 7 m (between the side wall and the central wall) and a floor slab thickness of 50 cm as an embodiment of the present invention. The formwork is shown.

  1 (a) is a plan view, FIG. 1 (b) is a cross-sectional view taken along the line AA, FIG. 1 (c) is a cross-sectional view taken along the line BB, and FIG. 2 (a) is a part of FIG. FIG. 2 (b) is an enlarged view of FIG. 1 (c).

  The main formwork components are a formwork bottom plate 11 and a steel rib member 12 arranged in parallel on the formwork bottom plate 11, and a large support work between the road side wall 1a and the central wall 1b as a support structure. In the state where it is bridged without using the reinforced concrete floor slab 2, a large-span reinforced concrete slab 2 is constructed on the upper portions of the support structures 1 a and 1 b by performing the reinforcement work described later and placing and curing the concrete 7. In addition, although the illustration of the road sidewall on the opposite side is omitted, the structure is almost symmetrical.

  In the present embodiment, the mold bottom plate 11 is formed by connecting a plurality of long strip steel plates having a width of 50 cm in the width direction with a connection plate 11a, and a long strip steel plate having a height of 25 cm as a steel rib member 12 on the upper surface thereof. By matching the longitudinal direction with the vertical mounting, the cross-sectional rigidity to withstand the concrete pouring pressure is secured. The formwork bottom plate 11 and the steel rib member 12 are integrated by bolting or welding in advance.

  In the present embodiment, the formwork receiving material 14 is installed on the upper surfaces of the road side wall 1a and the central wall 1b that have already been constructed, and the steel rib material 12 protruding from both ends of the formwork bottom plate 11 by the formwork receiving material 14. The extra length part is supported. In addition, a haunch portion bottom plate 15 is attached to both ends of the mold bottom plate 11 via a connecting member 16 to form a bottom mold frame of the haunch portion.

  A plurality of slits 13 are formed in the steel rib member 12 at intervals in the longitudinal direction. The slit 13 is formed so that the lower end thereof has a height corresponding to the cover thickness of the lower end stripes 3a and 3b of the floor slab to be constructed. By inserting the lower end stripe 3a in the direction orthogonal to the span direction of installation, It functions as a spacer for the lower end muscle 3a. If the slit 13 is formed in the shape of a long groove, the work of inserting and temporarily placing the lower end stripe 3a is easy.

  The mold bottom plate 11 does not need to be removed from the mold, and becomes a discarded mold frame together with the steel rib member 12, but the fire resistance is not included in the strength, and the constructed floor slab is designed as a reinforced concrete floor slab.

  As a general construction procedure, a formwork bottom plate 11 divided into a predetermined width and pre-attached with a steel rib member 12 is installed between the road side wall 1a and the central wall 1b without using a large support work. In the spanned state, the connecting plate 11a is connected in the width direction with a high strength bolt or the like.

  The construction on the road side wall 1a and the central wall 1b is performed in such a manner that the extra length portion of the steel rib member 12 is supported by the mold receiving member 14 as described above, and the haunch bottom plate 15 is set at the haunch position. Moreover, a necessary side mold or the like (not shown) is set for the concrete placement range.

  Next, a plurality of lower end bars 3a in the span orthogonal direction (a direction perpendicular to the longitudinal direction of the steel rib member 12) are inserted into the long groove-like slits 13 of the steel rib member 12, and according to the bar arrangement design. The interval is adjusted, and the lower end stripe 3b in the span direction is further placed on the lower end stripe 3a, and fixed with a binding wire or the like. Subsequently, the upper end bars 4a and 4b are arranged using a spacer (not shown).

  In this state, concrete is placed and cured to complete the floor slab. The formwork bottom plate 11 is left as it is as a discarded formwork, but the side formwork or the like may be either removed from the mold or left as a formwork.

  Depending on the width of the slab, the above operation is repeated several times.

  3 and 4 show another embodiment of the present invention, and the objects and construction conditions are the same as those of the embodiment of FIGS.

  3 is a vertical cross-sectional view, and FIGS. 4A to 4D show the construction procedure corresponding to FIG. 3, with the left-hand side view being an enlarged cross-sectional view seen from the span orthogonal direction and the right-side view being perpendicular thereto. It is an expanded sectional view of the direction to do.

  In the present embodiment, the steel rib material is divided into a lower rib material 22a and an upper rib material 22b, and these are joined by a high bolt or the like via a plurality of connecting plates 23. .

  By attaching the connecting plate 23 to the lower rib member 22a or the upper rib member 22b in advance, field work is facilitated. In that case, the side to be attached in advance may be welded instead of bolted.

  The lower rib member 22a is sufficient to support a load acting before placing concrete, such as an operator performing reinforcement work on the mold bottom plate 11 in a state of being arranged in parallel on the mold bottom plate 11. Ensure that cross-sectional rigidity is ensured.

  Thereafter, lower end bars 3a and 3b arranged on the concrete floor slab 2 are placed on the upper end portion of the lower rib member 22a, and the upper rib member 22b is connected to the lower rib member 22a via the connecting member 23. By doing so, the cross-sectional rigidity which can endure the load at the time of placement of the concrete 7 is ensured.

  In this case, since the lower end bars 3a and 3b arranged on the floor slab need only be placed on the upper end portion of the lower rib member 22a, the lower end bars 3a are provided in the slit 13 as in the embodiment of FIGS. Compared to the case of inserting the bar, the bar arrangement work is easier. Other configurations are the same as those of the embodiment of FIGS.

  As a general construction procedure, the frame bottom plate 11 divided into a predetermined width and previously attached with the lower rib member 22a is installed between the road side wall 1a and the central wall 1b without using a large support work. In the spanned state, the connecting plate 11a is connected in the width direction with a high-strength bolt or the like (see FIG. 4 (a)).

  Construction on the road side wall 1a and the central wall 1b is performed by supporting the extra length of the lower rib member 22a with the mold receiving member 14, and the haunch bottom plate 15 is set at the haunch position (see FIG. 3).

  Next, the lower end reinforcement 3a in the span orthogonal direction is placed on the upper end portion of the lower rib member 22a, the interval is adjusted according to the arrangement of the reinforcement, and the lower end reinforcement 3b in the span direction is further placed on the lower end reinforcement 3a. And fix it with a binding wire (see Fig. 4 (b)).

  After performing the bar arrangement work of the lower end bars 3a and 3b, the upper rib member 22b is connected to the upper side of the lower rib member 22a through the connecting plate 23 by high-strength bolt bonding or the like (see FIG. 4C).

  Subsequently, the upper end bars 4a and 4b are laid using a spacer (not shown), the concrete 7 is placed and cured, and the floor slab is completed (see FIG. 4 (d)). .

  Other operations are the same as those in the embodiment of FIGS.

  5 to 8 show other embodiments of the present invention, and the objects and construction conditions are the same as those of the embodiments of FIGS. 1 and 2.

  FIGS. 5-7 is a schematic perspective view at the time of using the hybrid formwork which combined the PCa plate and the steel rib material 12 with the formwork baseplate 11 of this invention, and has shown the construction procedure. The steel rib material is the same as in FIGS. 3 and 4, and is divided into a lower rib material 22 a and an upper rib material 22 b, and these are joined by a high bolt or the like via a plurality of connecting plates 23. It is a thing.

  First, as step 1, FIG. For the mold bottom plate 11, a PCa plate provided with a lower rib member 22a in advance at a factory or the like is used.

  The lower rib member 22a is sufficient to support a load acting before placing concrete, such as an operator performing reinforcement work on the mold bottom plate 11 in a state of being arranged in parallel on the mold bottom plate 11. Ensure that cross-sectional rigidity is ensured.

  By attaching the connecting plate 23 to the lower rib member 22a in advance, field work is facilitated. In that case, the side to be attached in advance may be welded instead of bolted.

  Next, as Step 2, FIG. 6 shows the bar arrangement below the floor slab. Lower end bars 3a and 3b arranged on the concrete floor slab 2 are placed on the upper end portion of the lower rib member 22a, and the lower rib member 22a is used as a spacer.

  As Step 3, FIG. 7 shows joining of the upper rib member 22b. The upper rib member 22b is connected to the lower rib member 22a via the connecting member 23 to ensure a cross-sectional rigidity that can withstand the load when the concrete 7 is placed.

  In this case, since the lower end bars 3a and 3b arranged on the floor slab need only be placed on the upper end portion of the lower rib member 22a, the lower end bars 3a are provided in the slit 13 as in the embodiment of FIGS. Compared to the case of inserting the bar, the bar arrangement work is easier.

  Further, the PCa plate can be used as a discarded formwork, and the thickness of the PCa plate can be used as a load-resistant coating (a part of the fog necessary for ensuring load-bearing performance).

  Other configurations and other operations are the same as those in the embodiment of FIGS.

  FIG. 8 shows a case where a steel reinforced concrete plate provided with channel steel as a reinforcing steel material is used for the PCa plate of the mold bottom plate 11 of the present invention, and FIGS. 8 (a) and 8 (b) are sectional views, FIG. 8C is a perspective view.

  As shown in FIGS. 8A to 8C, a plurality of holes are provided in each of the groove steel 31 and the lower rib member 22a, and the holes of the groove steel 31 and the lower rib member 22a are passed through. Reinforcing bars are provided to form a PCa plate.

  The hole provided in the channel steel 31 and the lower rib member 22 acts as a stopper, so that the concrete of the formwork bottom plate and the steel material can be integrated.

  Operations after the joining plate 23 is joined to the lower rib member 22a with a high bolt or the like and other configurations are the same as those in the embodiment of FIGS.

  When a steel frame reinforced concrete plate is used for the mold bottom plate 11, when concrete is placed on the main body, a load acts in such a direction that the lower rib member 22 a is pulled out from the mold bottom plate 11. However, by providing a reinforcing bar that penetrates the reinforcing steel member 31 and the lower rib member 22a, it is possible to efficiently resist this pulling load.

  Although the example in which the grooved steel 31 is installed outward in FIG. 8 (a) and inward in FIG. 8 (b) is shown, both are effective.

  Here, an example in which channel steel is used as the reinforcing steel material is shown, but a plurality of holes can be provided in the H-shaped steel and other reinforcing steel materials, and any material may be used as long as it has no problem in strength, and is not particularly limited.

DESCRIPTION OF SYMBOLS 1a ... Side wall (support structure), 1b ... Center wall (support structure), 2 ... Large span reinforced concrete floor slab, 3a, 3b ... Lower end reinforcement, 4a, 4b ... Upper end reinforcement, 5 ... Wall main reinforcement, 6 ... Shear reinforcement Muscle, 7 ... concrete,
DESCRIPTION OF SYMBOLS 11 ... Bottom plate, 11a ... Connection plate, 12 ... Rib material, 13 ... Slit, 14 ... Formwork receiving material, 15 ... Haunch part bottom plate, 16 ... Connection material,
22a ... lower rib material, 22b ... upper rib material, 23 ... connecting plate,
31 ... Reinforced steel (channel steel), 32 ... Rebar

Claims (6)

  A large-span concrete floor slab formwork for placing reinforced concrete floor slabs on a support structure, parallel to the formwork bottom plate and the formwork bottom plate, and capable of withstanding the load during concrete placement A plurality of steel rib members having a cross-sectional rigidity, wherein the steel rib members are formed with a plurality of slits on which reinforcing bars arranged on the concrete floor slab can be placed. Concrete floor slab formwork.   2. The large-span concrete floor slab form according to claim 1, wherein the steel rib member is a strip steel plate or a shape steel.   The large-span concrete floor slab form according to claim 1 or 2, wherein the slit is a long groove-like slit long in the longitudinal direction of the steel rib material.   A large-span concrete floor slab formwork for placing reinforced concrete floor slabs on a support structure, parallel to the formwork bottom plate and the formwork bottom plate, and capable of withstanding the load during concrete placement A plurality of steel rib members having a cross-sectional rigidity, wherein the steel rib members are capable of supporting a load acting before placing the concrete, and the lower rib members are connected via a connecting member. The upper rib member is divided into two parts, the upper rib member being detachable and supporting the load at the time of placing the concrete in a state where the lower rib member and the upper rib member are connected. A large-span concrete slab formwork characterized in that a reinforcing bar placed on the concrete slab can be placed on the part.   A large-span concrete floor slab form according to claim 1, 2, or 3 is laid between support spans by the support structure, and reinforcing bars are arranged in each slit in a direction perpendicular to the support span of the concrete floor slab. A method for constructing a reinforced concrete slab using a large-span concrete slab formwork, wherein one or a plurality of slabs are placed and concrete is placed.   5. A large-span concrete floor slab form according to claim 4, wherein the upper rib member is unconnected between support spans by the support structure, and the concrete floor slab is supported on the lower rib member. A large-span concrete floor characterized by placing a plurality of reinforcing bars arranged in a direction perpendicular to the span, connecting the upper rib material to the lower rib material using a connecting member, and then placing concrete. Construction method of reinforced concrete floor slab using plate formwork.