JPH07156130A - Manufacture of semi-pc beam - Google Patents

Abstract

PURPOSE:To form a horizontal construction joint face which does not need polishing and cleaning by casting concrete into a form with beam reinforcement kept inverted and while a part of the beam reinforcement to be exposed being buried in a bulk material. CONSTITUTION:A box type form 2 is mounted on a form bed 1, and the form 2 is filled with a bulk material 3. A mixture in which sand and water are mixed in a specified ratio is preferably used as the bulk material 3. For making a semi-PC beam having a U-shaped cross section, beam reinforcement composed of main bars 6 and ST bars 7 is installed to an outer form 4 and a core 5, and the assembly is placed on the box type form 2. It is preferable that a vibrator is attached under the form bed 1 to vibrate the bulk material 3. After the ends of the ST bars 7 being completely buried in the bulk material 3, the vibration is stopped, and concrete is cast into the form 4. When the concrete was cured, the outer form 4 and the core are removed, and the ST bars are extracted from the bulk material 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a half-PC beam, particularly a half-PC beam having a U-shaped cross section.

[0002]

[Prior art and its problems] Half-PCs that are frequently used when building floors by splicing in construction work
A beam, that is, a PC beam provided with a reinforcing bar for splicing by exposing one end of a strap bar (hereinafter, ST bar) from the upper end surface, is a well-known pre-assembled beam bar in a formwork. It is manufactured by placing and pouring concrete into the formwork to a height where the exposed part of the beam rebar remains by a predetermined size.

Therefore, a concrete bulge is generated around the beam rebar exposed from the upper end surface of the half-PC beam,
In addition, concrete often adheres to the exposed part of the beam rebar, and concrete ridges may be formed on parts other than around the beam rebar on the upper end surface of the half-PC beam. In order to prevent this from happening, it was necessary to carry out polishing and cutting as needed and to perform cleaning work carefully.

In recent years, the use of semi-PC beams having a U-shaped cross section (hereinafter referred to as U-shaped half PC beams), which have been increasingly used due to their characteristics of light weight and high strength, have the following problems in manufacturing. I have a point. In addition, U type half P
The C-beam is manufactured as shown in FIGS. Here, FIG. 7 is a cross-sectional view showing a state in which a part of the beam rebar is arranged at a predetermined position in the formwork, FIG. 8 is a cross-sectional view showing a state in which concrete is placed in the formwork, and FIG. 9 is obtained. It is a perspective view of a U-shaped half PC beam.

7 to 9, B is a U-shaped half-PC beam, 11 is an outer mold, 12 is an inner mold, 13 is a main bar, 14 is an ST bar assembled around the main bar 13, and 15 is a striking rod. It is concrete that has been installed. That is, in the U-shaped half-PC beam B, a beam rebar composed of a main bar 13 and an ST bar 14 located at the lower end is arranged between the outer mold 11 and the floating inner mold 12 as shown in FIG. Then, as shown in FIG. 8, subsequently, the concrete 15 is poured into the space formed between the outer mold 11 and the inner mold 12, and the concrete 15 is cured.

U-shaped half-PC beam B manufactured in this way
As shown in FIG. 9, as in the case of the solid half-PC beam, the concrete ridge X around the ST streak 14 and the concrete swell U other than the ST streak 14 and the ST streak are also present. Due to the influence of the concrete V or the like adhering to 14 itself, there arises a problem that, for example, it becomes difficult to arrange the formwork when building.

When the concrete is poured from between the outer mold 11 and the inner mold 12, the gap width is narrow, so that it takes a considerable amount of time to perform the driving so that the lateral pressures on both sides become uniform. Since it takes time and the concrete is not fully spread, it is difficult to obtain a good product, and it is difficult to efficiently obtain a high quality product.

[0008]

In order to solve the above problems, the present inventor has eagerly conducted research on a method for manufacturing a half-PC beam, and as a result, the beam rebar is turned upside down, that is, inverted. Place the beam rebar in the form in the state, half PC
If concrete is poured from the side corresponding to the lower end surface of the beam, this will be done from the opening with a large area, so the work will be completed in a short time, and the lateral pressure on both sides will of course be uniform. As the concrete flows in well, we have reached the revelation that we will be able to obtain high quality products.

However, in this case, of course, the interference between the projecting portion of the beam rebar and the form bottom plate cannot be avoided, so that a hole for inserting the beam rebar must be provided in the form bottom plate.
At the same time, it is necessary to consider the prevention of concrete leaks. Therefore, it was considered to use a special formwork in which the hole portion is pressed against the periphery of the beam rebar to close the gap, but this formwork is very troublesome to manufacture, so it becomes expensive, Moreover, it has a drawback that it takes a lot of time and effort to install and remove.

As a result of further research conducted by the present inventor, as a result, the concrete bottom was poured into the concrete without using the bottom plate of the formwork and the exposed portion of the beam reinforcement was buried in a granular material such as sand. It has been found that, by doing so, there is no adhesion of concrete to the buried part of the beam reinforcing bar, and a high quality product in which no concrete lumps are formed in the peripheral part of the beam reinforcing bar can be obtained.

It has also been found that when the beam reinforcing bars are embedded in the granular body, if the granular bodies are vibrated, the granular bodies are liquefied, so that the beam reinforcing bars can be embedded more easily. The present invention has been made based on the above findings, and an object of the present invention is to easily and efficiently obtain a high quality semi-PC beam having a horizontal piecing joint surface that does not require polishing or cleaning work. It is to provide a method of manufacturing a semi-PC beam capable of manufacturing.

An object of the present invention is to provide a method for manufacturing a half-PC beam in which a part of the beam rebar is exposed from the upper end surface, wherein the beam rebar is set upside down and exposed from the upper end surface of the half PC beam. Of a half-PC beam, the method comprising the steps of arranging a portion of the beam rebar to be embedded in a granular body and placing concrete in a formwork located outside the beam rebar. This is achieved by the manufacturing method.

A method of manufacturing a half-PC beam, in which a part of the beam rebar is exposed from the upper end surface, wherein the beam rebar is set upside down, and the beam rebar is exposed from the upper end surface of the half PC beam. A step of arranging a part thereof to be buried in a granular body; and a step of placing concrete in a space having a substantially U-shaped cross section formed by a mold located outside and inside the beam rebar. Is achieved by a method for manufacturing a half-PC beam.

It is preferable that the beam rebar is attached to the formwork in advance before a part of the beam rebar is embedded and arranged in the granular body. Further, it is preferable that the granular material is filled in a box-shaped mold, and the box positioned around the beam rebar is brought into contact with the box-shaped mold.
Further, in the step of arranging the portion exposed from the upper end surface of the half-PC beam so as to be embedded in the granular body, it is preferable that vibration is applied to the granular body.

The granules are preferably made of a mixture of sand and water in a predetermined ratio. Further, it is preferable that an insulating material is laid on the surface of the granular body before the beam reinforcing bar is arranged, and in particular, a cut corresponding to the beam reinforcing bar portion is formed at a predetermined position of this insulating material. Is preferred.

[0016]

1 to 5 show an embodiment of a method for manufacturing a half-PC beam according to the present invention. FIG. 1 is a sectional view showing a state in which a box-like mold is filled with a granular material. 2 is a cross-sectional view showing the arrangement of the beam rebars attached to the formwork, FIG. 3 is an enlarged cross-sectional view showing the laying state of the insulating sheet, and FIG. 4 is a cross-sectional view showing the state of placing concrete in the formwork, FIG. 5 is a perspective view of the obtained U-shaped half-PC beam.

In each drawing, A is a U-shaped half-PC beam, 1 is a form bed made of steel plate, etc., and the form bed 1 is moved in a predetermined direction by a vibration generator (not shown) provided below. It is configured to be able to vibrate. Reference numeral 2 denotes a box-shaped frame, and its height h may be equal to or larger than the exposed length 1 of the ST muscle or larger than that. In the present embodiment, it is necessary to bear a part of the load on the ST muscle. From the end of the ST muscle to the form bed 1, that is, the height h of the box form 2
Is equal to the exposed length l of the ST muscle.

Reference numeral 3 is a granular material composed of sand to which an appropriate amount of water is added. The granular body 3 to be filled in the box-shaped mold 2 is not limited to the combination of sand and water, but may be any one having a characteristic of being liquefied by vibration. However,
It is preferable that the concrete material has a density similar to or higher than that of the concrete material described later. 4 is an outer mold, 5 is a core (inner mold), and especially the outer mold 4 is the side plates 4a, 4
b, and a joint 4c that connects the side plate 4a and the side plate 4b at an appropriate interval along the axial direction of the half PC beam.

6 is the main bar, and 7 is S combined with the main bar 6.
As the T muscle, the ST muscle 7 has a substantially U-shape with the tip of the exposed portion bent at about 135 °. Reference numeral 8 is an insulating sheet laid so as to cover the surface of the granular body 3, and, for example, water-resistant paper or non-woven fabric is used,
A cut is formed in the portion through which the ST muscle 7 is inserted.

That is, since the cast concrete and the granular material 3 are completely separated by the insulating sheet 8, as will be described later, they do not mix with each other, and even after the concrete is hardened, it is insulated. A simple concrete surface can be obtained simply by peeling off the sheet 8, and cleaning work is unnecessary. As the insulating sheet 8, it is not always necessary to use a large one that covers the entire surface of the granular body 3. For example, a long sheet having a width that can cover only the portion where the ST streak 7 is buried is used. It may be provided along the axial direction of the half-PC beam, or a plurality of sheets may be provided at a predetermined interval so as to be orthogonal to the axial direction of the half-PC beam only in the portion where the ST streak 7 is buried.

Reference numeral 9 is concrete that has been cast. In this embodiment, first, as shown in FIG. 1, a box-shaped mold 2 is installed on a mold bed 1, and sand and water are mixed in the box-shaped mold 2 at a predetermined ratio. The granules 3 are filled. Subsequently, as shown in FIG. 2, a beam reinforcing bar formed by assembling main bars 6 and ST bars 7 by vibrating the granular body 3 in the box-shaped mold 2 by a vibration generator provided below the mold bed 1. The outer mold 4 and the core 5 are attached to the box-shaped mold 2.

At this time, since the granular body 3 is liquefied by the vibration, the end portion of the ST streak 7 is smoothly embedded in the granular body 3 and is laid on the surface of the granular body 3 as shown in FIG. Since the formed insulating sheet 8 has a cut, it does not prevent the ST muscle 7 from entering. Note that, as can be seen from FIG. 2, the beam reinforcing bars are in an inverted state, and the surface to which the splice is made at the time of building is formed on the side facing the granular body 3.

After the end portion of the ST muscle 7 is completely buried in the granular body 3, the vibration is stopped and the granular body 3 is stabilized. At this time, the hardness of the sand can be appropriately adjusted by discharging water or injecting an admixture as necessary. After the space for placing concrete is formed as described above, concrete 9 is placed in the mold as shown in FIG.

Since the insulating sheet 8 is interposed at the boundary surface between the granular material 3 and the concrete 9 as described above, they do not mix with each other, and the sand particles are formed on the surface portion which becomes the upper end surface when building. Is never attached,
Therefore, cleaning after curing is unnecessary. After the concrete is hardened, the outer form 4 and the core 5 are removed, and the ST streak 7 is further pulled out from the granular body 3 to obtain an extremely high quality U-shaped half PC beam A as shown in the perspective view of FIG. can get.

As described above, according to the method of manufacturing a half-PC beam of the present invention, when manufacturing a half-PC beam having a U-shaped cross section, concrete can be poured from the bottom side of the half-PC beam having a wide opening. The time required for placing concrete can be greatly reduced and the work can be simplified. Moreover, the lateral pressure of the concrete is uniform on both sides, and the concrete is sufficiently spread to all parts in the formwork, so that it is possible to obtain a high-quality concrete product with no recesses or defects on the surface. .

Further, also on the jointing surface where the ST streak protrudes, it is difficult to cause problems such as bulging of concrete, adhesion of concrete to the ST streak, and formation of a convex portion on the concrete placing surface, and an extremely smooth horizontal surface can be obtained. Therefore, it is possible to build immediately without performing the smoothing treatment and concrete removal treatment that were indispensable in the conventional method.
Can perform efficient construction.

In the above embodiment, the manufacture of the U-shaped half-PC beam has been described, but the manufacture of a normal half-PC beam can be carried out in the same manner, that is, in this case, the core 4 is not used and concrete is used. By adopting this method, it is not necessary to remove or clean the concrete ridges around the exposed ST streaks, and the manufacturing work is greatly simplified.

Further, the ST muscle may have a shape other than the U-shape, for example, as shown in FIG.
The T muscle 10 can be used. In this case, it is preferable to make a long cut corresponding to the width of the loop-shaped ST streak 10 in the insulating sheet.

[0029]

According to the present invention, a high-quality semi-PC beam having a horizontal piecing surface that does not require polishing or cleaning work can be easily manufactured.
And it can be obtained efficiently.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a granular material is filled in a box-shaped mold.

FIG. 2 is a cross-sectional view showing an arrangement state of beam reinforcing bars attached to a formwork.

FIG. 3 is a cross-sectional view showing a laid state of an insulating sheet.

FIG. 4 is a cross-sectional view showing a state in which concrete is placed in a formwork.

FIG. 5 is a perspective view of the obtained U-shaped half-PC beam.

FIG. 6 is a cross-sectional view of a U-shaped half-PC beam with looped strap streaks.

FIG. 7 is a cross-sectional view showing an arrangement state of beam reinforcing bars in a mold according to a conventional method.

FIG. 8 is a cross-sectional view showing how concrete is cast into a mold according to a conventional method.

FIG. 9 is a perspective view of a U-shaped half-PC beam obtained by a conventional method.

[Explanation of symbols]

 AU type half PC beam 1 Form bed 2 Box form 3 Granular body 4 Outer form 5 Core (inner form) 6 Main bar 7 Strap bar (ST bar) 8 Insulation sheet 9 Concrete 10 Loop strap bar

Claims (8)

[Claims] 1. A method of manufacturing a half-PC beam, wherein a part of the beam reinforcing bar is exposed from the upper end surface, wherein the beam reinforcing bar is set upside down, and the beam reinforcing bar is exposed from the upper end surface of the half PC beam. A method of manufacturing a half-PC beam, comprising: a step of arranging a part of the beam to be embedded in a granular body; and a step of placing concrete in a formwork located outside the beam rebar. 2. A method for manufacturing a half-PC beam, wherein a part of the beam reinforcing bar is exposed from the upper end surface, wherein the beam reinforcing bar is inverted and the beam reinforcing bar exposed from the upper end surface of the half PC beam is used. A step of arranging a part thereof to be buried in a granular body; and a step of placing concrete in a space having a substantially U-shaped cross section formed by a mold located outside and inside the beam rebar. A method for manufacturing a half-PC beam, comprising: 3. The semi-PC beam of claim 1 or 2, wherein the beam rebar is attached to the formwork in advance before a part of the beam rebar is embedded and arranged in the granular body. Production method. 4. The granular body is filled in a box-shaped mold, and the box positioned around the beam rebar is brought into contact with the box-shaped mold. The method for manufacturing a half-PC beam according to claim 1. 5. The method according to claim 1, wherein in the step of arranging the part exposed from the upper end surface of the half-PC beam so as to be buried in the granular body, vibration is applied to the granular body. PC beam manufacturing method. 6. The granular material is formed by mixing sand and water in a predetermined ratio.
Manufacturing method of half-PC beam. 7. The method of manufacturing a half-PC beam according to claim 1, wherein an insulating material is laid on the surface of the granular body before the beam reinforcing bars are arranged. 8. The method of manufacturing a half-PC beam according to claim 7, wherein a cut corresponding to the beam reinforcing bar portion is formed at a predetermined position of the insulating material.