JPH1161741A - Precast form and structure of floor slab using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a floor slab easily and rapidly on a bridge girder while surely ensuring the strength of the floor slab. SOLUTION: Form main body 31 formed in a plate shape, ribs 32 projecting from both side of the form body 31 to the lower side along the longitudinal direction and mounting 33 projecting in parallel with the form body 31 from the ribs 32 to the sides are molded integrally of concrete, thus constituting the precast forms 21. Lower-side distributing bars assembled in a lattice shape are buried into the form body 31, and parts of lower bars 3 (3a) configuring the lower-side distributing bars are projecting from both side sections of the form body 31 and used as lower-bar connecting parts 3a. The connecting parts 3a are lapped mutually in the bridge axial direction while a plurality of the connecting parts 3a are juxtaposed onto bridge girders 22 in the bridge axial direction, and concrete C is placed under the state, in which upper-side distributing bars 6 are disposed on the top face sides, and cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast formwork for constructing an elevated road such as an expressway and a structure of a floor slab using the formwork.

[0002]

2. Description of the Related Art Conventionally, a precast formwork has been used in order to shorten a construction period of an elevated road such as an expressway and to improve the efficiency of construction work. Here, a conventional example of the precast formwork will be described with reference to the drawings. In FIG.
Reference numeral 1 is a precast formwork. The precast form 1 is made of a plate material formed in advance of concrete or the like, and the precast form 1 is supported on a bridge girder.
A lower reinforcing bar 5 and an upper reinforcing bar 6 each having a lower bar 3 and an upper bar 4 combined with a main bar 2 are arranged on the upper portion thereof, and then, concrete C is cast on the upper surface side of the precast formwork 1 by cast-in-place. And the floor slab 7 was constructed.

[0003]

By the way, in the above-mentioned precast formwork 1, a floor slab made of concrete C in which a lower distribution reinforcement 5 and an upper distribution reinforcement 6 are buried above the precast form1. Since the structure provided with the portion 7a, that is, the structure in which the precast form 1 is not a part of the floor slab 7, was not expected from the precast form 1 as the floor slab 7. Therefore, the floor slab 7 has a problem that the weight is increased by the amount of the precast formwork, and the strength of the pier, the bridge girder, and the like must be increased, which leads to an increase in cost. For this reason, as shown in FIG. 8, a precast formwork 11 having a function as a part of the floor slab 7 in which a lower distribution reinforcing bar 5 composed of the main bar 2 and the lower bar 3 is embedded in advance is provided. Used. That is, the precast form 11 is supported on a bridge girder, and the upper force distribution reinforcing bar 6 is disposed on the upper part thereof. Then, concrete C is cast on the upper surface side of the precast form 11 by cast-in-place, and the floor slab is formed. 7 had been built.

[0004] At the joints between the precast molds 11, the lower streaks 3 protruding from the end faces of the respective precast molds 11 are wrapped with each other, and the molds 12 are installed below the joints. Concrete C was cast in the state and integrated. By the way, in this precast form 11, in order to sufficiently transmit the stress of the lower muscle 3 at the joint, the lower muscle 3 must be sufficiently wrapped. The space between each other becomes large, and in this portion, it is necessary to use a special formwork 12 for cast-in-place concrete C on the lower surface side. In other words, the joint is in the same state as a conventional cast-in-place concrete slab that does not use the precast formwork 11, and the advantage of using the precast formwork 11 is impaired. Also, when the space between the precast forms 11 is narrowed,
There has been a problem that the stress transmission of the lower muscle 3 becomes insufficient, and the strength of the floor slab 7 at this seam is greatly reduced. In addition, since the joint between the end face 11a of the precast form 11 and the cast-in-place concrete C is not well adapted to each other, when a wheel load is applied, cracks and cracks may occur along the joint. was there.

[0005] Further, in the above-mentioned precast forms 1 and 11, both of them are bent particularly when the bridge girder, that is, the span is large, and the finished surface of the upper surface of the floor slab 7 is lowered by that much. turn into. Here, this floor slab 7
If the construction is performed with priority given to the accuracy of the finished surface on the upper surface, the floor slab 7 becomes unnecessarily thick due to the bending of the precast forms 1 and 11, and the weight increases.

The present invention has been made in view of the above circumstances and makes it possible to construct a floor slab on a bridge girder very easily, does not bend when concrete is poured, and furthermore, cracks and cracks due to wheel loads. It is an object of the present invention to provide a precast formwork that can be reduced in weight and a floor slab structure using the same.

[0007]

In order to achieve the above object, a precast formwork according to claim 1 is formed in advance of concrete, is installed on a girder in the bridge axis direction, and casts concrete on an upper portion thereof. By doing so, it is a precast formwork for constructing a floor slab that forms an elevated road together with the cast concrete, the formwork body portion formed in a flat plate shape, and both sides of the formwork body portion along the longitudinal direction. A rib portion protruding downward, and an installation portion protruding laterally from the end of the rib portion substantially in parallel with the mold body,
In the formwork body, a reinforcing bar assembled in a lattice shape is buried, and a part thereof is protruded from both sides to be a connecting portion, and the connecting portion is adjacent to the precast when it is installed on the girder. It is characterized in that it is wrapped with the connecting portion of the formwork.

According to a second aspect of the present invention, there is provided the precast formwork according to the first aspect, wherein the formwork body, the ribs, and the installation section are integrally formed of concrete. And Claim 3
In the structure of the floor slab using the precast formwork according to claim 1, the plurality of precast formworks according to claim 1 or 2 are provided on the girder, and a reinforcing bar arranged in a grid on the upper surface side is provided. It is characterized in that concrete is cast on the upper surface side so that the rebar is buried.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a precast mold according to the present invention and a structure of a floor slab using the same. The same components as those of the conventional technology are denoted by the same reference numerals, and description thereof is omitted. In FIG.
Is a precast formwork integrally formed of concrete in advance. The precast formwork 21 is bridged over a bridge girder 22, and a plurality of the precast formwork 21 are arranged in parallel in the axial direction of the bridge girder 22. The floor slab 23 is constructed on the bridge girder 22 by arranging the upper distribution steel bars 6 on the upper surfaces of the precast formwork 21 and casting concrete C.

As shown in FIG. 2, the precast mold 21 has a mold body 31 formed in a flat plate shape. Both sides of the mold body 31 extend in the longitudinal direction. And a rib portion 32 bent downward and projected is formed,
Further, the form body 3
The installation part 33 extends substantially in parallel with 1. That is, the precast mold 21 has a Z-shaped cross section including the ribs 32 and the installation portions 33 near both ends of the mold body 31.

A lower distribution reinforcing bar 5 is buried inside the precast formwork 21, and the lower reinforcement 3 constituting the lower distribution reinforcing bar 5 is formed on both sides of the form body 31. From the side. The lower muscle 3 protruding from the form body 31 is a lower muscle connecting portion (connecting portion) 3a, and the distal end thereof is bent upward. In addition, the installation portion 33 extending laterally from the end of the rib portion 32
The main reinforcement 2 is buried inside the main reinforcement 2, and the main reinforcement 2 and the outermost main reinforcement 2 of the formwork body 31 are provided with an installation portion 3.
The connection reinforcing bars 34 embedded in the ribs 3 and the ribs 32 are fixed. The ends of the connection reinforcing bars 34 on the side of the form body 31 protrude obliquely upward from the upper surface of the form body 31.

A plurality of pretend piano wires 35 are arranged in the precast form frame 21 along the longitudinal direction at intervals in the width direction.
By pretensioning the mold 5 during molding of the precast mold 21, prestress is introduced. The installation part 33 has a plurality of insertion holes 36 at the contact points with the bridge girder 22.
As shown in FIG. 3, bolts 37 for connection to the bridge girder 22 are inserted into these insertion holes 36. That is, the precast formwork 21 is disposed on the bridge girder 22, and the insertion hole 36 formed in the installation part 33 and the hole 22a formed in the bridge girder 22 are communicated with each other, so that the bolt 37 is inserted. By fastening a nut 38 to 37, the precast formwork 21 is fixed on the bridge girder 22.

As shown in FIG. 4, a positioning joint plate 41 formed in an L-shape in a side view is fixed to an end of the installation portion 33 by bolts or the like. The positioning joint plate 41 has a positioning plate portion 43 in which a hole portion 42 is formed.
When installed on the upper side, it comes into contact with the positioning plate portion 43 of the positioning joint plate 41 of the adjacent precast formwork 21. That is, the precast formwork 21 is
Positioning plate 4 that abuts each other when installed on top
By inserting the drift pins 44 into the holes 42 of No. 3, the upper, lower, left and right positions of the positioning plate portions 43 are matched, whereby the adjacent precast molds 21 are positioned.

An injection port 45 is formed in the form body 31 at a position above the bridge girder 22 when the form body is disposed on the bridge girder 22. The provided concrete C flows from the injection port 45 to the lower surface side. That is, as shown in FIG. 5, when the precast formwork 21 is disposed on the bridge girder 22, weir plates 46 are provided on both sides of the bridge girder 22 in gaps formed on the upper surfaces of the precast formwork 21 and the bridge girder 22. When concrete C is cast on the upper surface side of the precast formwork 21 in this state, the concrete C is injected from the injection port 45 into the precast formwork 21, the bridge girder 22 and the weir plate 4.
6, the space C is filled with concrete C, and is integrated with a stud 47 erected on the bridge girder 22.

The precast mold 21 has the same cross section over the entire length and has a predetermined length (for example, 100 mm).
m), and is integrally formed with a length, provided with a pre-tension by providing a piano wire 35 if necessary, cut into a predetermined length after curing, and manufactured. However, the pretension does not need to be applied finely.

Next, a case where the floor slab 23 is constructed by the precast mold 21 having the above configuration will be described. (1) First, the precast formwork 21 is disposed on the bridge girder 22, and the bridge girder 22 and the installation portion 33 of the precast formwork 21 are connected by bolts 37 and nuts 38. (2) Next, the positioning plate portion 4 of the positioning joint plate 41 provided at the end of the installation portion 33 of each precast mold 21
The drift pins 44 are inserted into the holes 42 of the third mold 3 to position the adjacent precast molds 21 particularly in the vertical direction. By doing so, the lower muscle connecting portions 3a protruding from both sides of the precast mold 21 are in a state of being wrapped with each other.

(3) In this state, as shown in FIG. 3, joints 51 are filled in joints formed by gaps between the end faces of the installation portions 33 of the adjacent precast molds 21, sealed and wrapped together. Lower muscle connecting part 3a in the state
A plurality of reinforcing bars 52 are provided along the longitudinal direction of the precast formwork 21 and are fixed to the lower bar connecting portion 3a by welding or the like. In addition, dam plates 46 are attached to both sides of the bridge girder 22 between the precast formwork 21 and the bridge girder 22. (4) After the precast formwork 21 is arranged as described above, as shown in FIG. 6, the upper force distribution reinforcing bar 6 is arranged above the precast formwork 21, and thereafter, is set to a predetermined height. Concrete C is cast, hardened and cured. Here, when the concrete C is cast as described above, the concrete C is injected into the injection port 45 of the formwork body 31.
Flows into the lower side of the precast formwork 21, and the space C surrounded by the precast formwork 21, the bridge girder 22, and the weir plate 46 is filled with the concrete C. And when this concrete C hardens, the precast formwork 21
The gap S between the bridge girder 22 and the bridge girder 22 is closed by the concrete C, and is integrated with the stud 47 provided on the bridge girder 22 to combine the completed floor slab 23 and the bridge girder 22. In addition, although the said precast formwork 21 and the bridge girder 22 were compounded by concrete C, it is good also as non-composite.

As described above, according to the precast mold 21 of the above example, both sides of the plate-shaped mold main body 31 are Z-shaped having the ribs 32 and the mounting portions 33, so that the whole is formed. , The bending rigidity in the longitudinal direction is higher than that of the conventional flat precast molds 1 and 11, whereby the transportation can be performed without considering the strength. Even when the floor slab is constructed, the bending is minimized, and the upper surface of the floor slab 23 does not fall down due to the bending of the precast formwork 21. In addition, extra concrete C is used to prevent falling. Therefore, the weight of the floor slab 23 does not need to be increased, and the cost due to the extra use of the concrete C can be prevented.

Further, since the end faces of the installation portion 33 are used by abutting each other, a larger gap is formed at the joint as compared with the conventional precast mold 11 in which the lower reinforcing steel bars 5 are embedded. There is nothing. That is, the bridge girder 22
When laid on the top, the entire bridge floor is covered, so that only work on the upper surface of the precast formwork 21 is required at the time of site construction, and the work is efficient and safe. In addition, since the rebar is assembled only by the upper distribution rebar 6, the rebar can be quickly constructed.

Further, according to the floor slab 23 constructed using the above-mentioned precast formwork 21, since the lower reinforcement connecting portions 3a are wrapped with each other in the bridge axis direction and integrated with concrete C, the precast type Frame 21 to floor slab 23
, Thereby preventing the floor slab 23 from being unnecessarily thick for securing strength. That is, unlike the simple precast form 1, the precast form 21 can function as a part of the floor slab 23 without waste. Further, like the conventional precast formwork 11, the end face 11a and the concrete C
Since there is no seam, there is no occurrence of cracks, cracks, etc. along the seam even when a wheel load is applied.

The downwardly protruding Z-shaped portion consisting of the rib portion 32 and the installation portion 33 functions as a cross beam and stiffens the floor slab 23 in the span direction, so that the floor slab 23 becomes anisotropic. A floor slab (having different strength depending on the direction) will be formed. That is, the bending moment in the span direction (Mx in FIG. 1) increases, and the bending moment in the bridge axis direction (Mx in FIG. 1).
Middle My) is reduced, whereby the bending moment acting on the discontinuous portion (seam portion) of the precast formwork 21 is reduced. In other words, the discontinuous portion, which is relatively disadvantageous in strength, is strengthened by the rib portion 32 and the installation portion 33 and the bending moment in the bridge axis direction is reduced, so that a double advantageous state is provided. .

[0022]

As described above, according to the precast form of the present invention and the structure of the floor slab using the same, the following effects can be obtained. According to the precast formwork of claim 1, Z having a rib portion and an installation portion at both ends.
Because it is a mold, its bending rigidity in the longitudinal direction is greater than that of a flat precast formwork, so that it can be transported without considering strength, and when building a floor slab However, the deflection is reduced as much as possible, so that the upper surface of the floor slab does not fall down due to the bending of the precast formwork, and there is no need to cast extra concrete to eliminate the falling down, An increase in the weight of the plate and an increase in cost due to the use of extra concrete can be avoided. In addition, since the end surfaces are used in abutting manner, no gap is formed at the joint as compared with the conventional precast formwork in which only the lower distribution steel bars are buried. In other words, when laid on a bridge girder, it will cover the entire bridge floor, so only work on the top of the precast formwork at the time of site construction,
Work is efficient and safe. In addition, since the rebar is assembled only by the upper distribution rebar, it can be constructed quickly.

According to the precast mold of the second aspect, since the mold main body, the rib, and the installation portion are integrally formed of concrete, the rigidity can be further increased. According to the structure of the floor slab using the precast form according to claim 3, since the connecting portions are wrapped with each other and integrated by concrete, the precast form can function as a structure of the floor slab. This makes it possible to prevent the floor slab from being unnecessarily thick for securing the strength. That is, unlike a simple precast formwork, it can function as a part of the floor slab without waste. Furthermore, since there is no seam between the end face and the concrete unlike the conventional precast formwork, cracks, cracks, and the like do not occur along the seam even when a wheel load is applied. Also, the downwardly protruding Z-shaped portion consisting of the rib portion and the installation portion functions as a cross beam and stiffens the floor slab in the span direction, so that the floor slab is anisotropic (strength varies depending on the direction). A floor slab will be formed. That is, the bending moment in the span direction increases, and the bending moment in the bridge axis direction decreases, whereby the bending moment acting on the discontinuous portion (joint portion) of the precast formwork decreases. That is, the discontinuous portion, which is relatively disadvantageous in strength, is strengthened by the rib portion and the installation portion, and the bending moment in the bridge axis direction is reduced, so that a double advantageous state is provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a viaduct for explaining the structure of a precast formwork and a floor slab using the same according to an embodiment of the present invention.

FIG. 2 is a side view of the precast formwork for explaining the configuration and structure of the precast formwork according to the embodiment of the present invention.

FIG. 3 is a side view of a joint portion of the precast formwork for explaining a structure of the precast formwork according to the embodiment of the present invention and a method of installing the same.

FIG. 4 is a side view and a front view of the positioning joint plate for explaining the shape and function of the positioning joint plate provided on the precast mold according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view in the width direction of the floor slab for explaining the installation structure of the floor slab on the bridge girder using the precast formwork according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view in the bridge axis direction of the floor slab at a joint portion of the precast form, illustrating a structure of the floor slab using the precast form according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view of a floor slab constructed using a conventional precast formwork.

FIG. 8 is a cross-sectional view of a floor slab constructed using a precast formwork in which a conventional distribution reinforcing bar is embedded.

[Explanation of symbols]

 3a Lower bar connecting portion (connecting portion) 5 Lower distributed reinforcing bar (reinforcing bar) 6 Upper distributed reinforcing bar (reinforcing bar) 21 Precast formwork 22 Bridge girder (girder) 23 Floor slab 31 Formwork body portion 32 Rib portion 33 Installation portion C concrete

Claims (3)

[Claims] 1. A precast formwork that is formed in advance of concrete and is provided on a girder in the direction of a bridge axis, and concrete is cast on an upper portion thereof to construct a floor slab that forms an elevated road together with the cast concrete. A mold body formed in a flat plate shape, ribs protruding downward along the longitudinal direction on both sides of the mold body, and the mold being laterally extended from an end of the rib. A main body part and an installation part protruding substantially parallel to the main body part, the formwork main body part is buried with a reinforcing bar assembled in a lattice shape, a part of which is protruded from both sides to form a connecting part. The connecting portion is wrapped with a connecting portion of an adjacent precast form when the connecting portion is provided on the girder. 2. The precast mold according to claim 1, wherein said mold body, said ribs, and said installation part are integrally formed of concrete. 3. A plurality of the precast forms are provided on the girder, a reinforcing bar arranged in a grid on the upper surface side, and a concrete on the upper surface side so that the reinforcing bar is buried. 2. The device according to claim 1, wherein the device is cast.
Or the structure of the floor slab using the precast formwork of Claim 2.