JPH06294135A - Underground beam construction method - Google Patents

Abstract

PURPOSE:To eliminate the need for connection work which connects two precast concrete boards as a form and further reduce reinforcing bar arrangement work as well on a construction site in terms of underground beam construction method installed in a foundation area of a building. CONSTITUTION:Two precast concrete boards 15 are connected to each other with spacing holding reinforcing bars 13 in a shop, thus keeping a specified spacing. Vertical reinforcing bars 11A, which constitute a vertical portion of stirrup bars 11, are also buried. U type reinforcing bars 11B on permanent concrete already cast and the vertical reinforcing bars 11a constitute lap slices on a site. U-type reinforcing bars 11c which constitute the upper end of the stirrup bars 11 and upper main reinforcing bars 9 are framed preliminarily and they are covered from above so that the U type reinforcing bars 11C and the vertical reinforcing bars 11A constitute lap slices.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing an underground girder provided in a foundation of a building.

[0002]

2. Description of the Related Art For example, an underground beam provided as a reinforced concrete building foundation has been constructed as follows. In other words, excavate the underground, put abandoned concrete,
Underground beams and a part of the building will be integrated and concrete will be placed on it. At this time, the lower end main bar was reinforced at the lower end of the underground beam, that is, the upper part of the abandoned concrete, while the upper end main bar was reinforced at its upper end, that is, inside the building.
Then, the stirrup reinforcement is arranged in the vertical direction by winding around the lower end main reinforcement and the upper end main reinforcement.

In actual construction, it is conceivable to use two form members that form both side surfaces of the underground beam and leave them as they are after pouring concrete (Japanese Patent Publication No. 54-5207). In this case, the two formwork materials connected to each other with a member called a separator are used so that the two formwork materials installed on the discarded concrete do not fall outside due to the lateral pressure of the poured concrete. ing.

[0004]

However, according to the conventional construction method, a large amount of work is required for bar arrangement work and formwork erection work, handling of heavy objects, and underground work in the case of a large building. Since the height of the beam is increased and the amount of work at a high place is increased, labor saving is desired.

Further, in order to save labor, as described above, 2
Even in the case of using one sheet of form material, it is necessary to perform a connecting work with a separator in order to prevent the form materials from collapsing. In addition, a complicated work of arranging reinforcing bars, that is, stirrup bars, for strengthening the underground beam between the connected frame members has to be performed on site.

The present invention has been made to solve the above problems, and uses two precast concrete plates as a formwork, and further, the connection work by a separator is not necessary, and the work on site can be reduced. The purpose is to provide a construction method for beams.

[0007]

In order to achieve the above object, the present invention integrates the upper end of an underground beam into a building and arranges a lower end main bar and an upper end main bar at the lower end and the upper end. In the method of constructing an underground girder constructed by arranging a stirrup bar between the bottom main bar and the top main bar, the longitudinal bars that make up the vertical part of the stirrup bar are embedded, and both side surfaces of the underground girder are embedded. The two precast concrete plates that form the mold and form the formwork are integrally joined to each other by preliminarily maintaining a predetermined space by the space-retaining bar, and on the other hand, the bottom main bar is placed on the cast concrete. A U-shaped bar that is wound to form the lower end of the stirrup bar is placed, then the unitized precast concrete plate is installed on the discarded concrete, and then a U-shaped bar that constitutes the upper end of the stirrup bar. A precast concrete plate with the upper end main bar pre-assembled is covered from above, and the U-shaped bar and the vertical bar at the upper and lower ends of the stirrup bar are made into a lap joint structure, and then the unitized precast concrete plate is built. It is characterized by attaching the formwork on the side and finally pouring concrete.

According to the second aspect of the present invention, the space retaining muscles are truss muscles or spiral muscles.

[0009]

[Operation] Two precast concrete boards, which will be the formwork of the underground beam, are unitized in advance. At this time, the precast concrete plates are integrally joined to each other by the spacing-reinforcing bars, and the precast concrete plates are also arranged with vertical streaks constituting the vertical portion of the stirrup bar.

At the site, the U-shaped bar wound around the lower main bar and constituting the lower end of the stirrup bar is placed on the already cast concrete, and the unitized precast concrete plate is installed. From above, a U-shaped bar that constitutes the upper end of the stirrup bar and the upper main bar are preliminarily ground. Therefore, the work of arranging the work in the field is saved. At this time, the U-shaped reinforcements at the upper and lower ends of the stirrup reinforcement and the vertical reinforcement form a lap joint. Then, attach the formwork on the building side to the precast concrete board, and then place concrete,
Underground beams and buildings will be built together.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, an underground beam 3 is provided on a waste concrete 1 in the underground portion. Further, the floor slab 5 of the building is integrally provided on the underground beam 3. At the lower end of the underground beam 3, that is, at the upper part of the discarded concrete 1, a lower end main bar 7 is horizontally arranged. Similarly, an upper end main bar 9 is arranged horizontally in the upper end of the underground beam 3, that is, inside the floor slab 5. A stirrup bar 11 is arranged by being wound around the upper end main bar 9 and the lower end main bar 7. The stirrup muscle 11 has a substantially rectangular shape as shown in the drawing, is arranged in the vertical direction, and opposes the shearing force. Further, truss muscles are arranged in the lateral direction as the space keeping muscles 13. As will be described later, the space retaining ribs 13 are preliminarily embedded in two precast concrete plates 15 forming both side surfaces of the underground beam 3. The formwork 17 supporting the lower surface of the floor slab 5 is also a precast concrete board.

The procedure of this embodiment will be described below with reference to FIG. First, the two precast concrete plates 15 that form the form of the underground beam 3 are unitized in advance in a factory. That is, the interval holding muscles 13 are maintained at a predetermined interval.
Are integrally joined to each other.

The spacing-retaining bars 13 are arranged with respect to the reinforcing bars 18 of the precast concrete plate 15 itself. Therefore, after the precast concrete board 15 is manufactured, the space retaining ribs 13 are partially embedded in the precast concrete board 15. Further, the vertical streaks 11A are arranged in the precast concrete plate 15. The vertical streak 11A constitutes a vertical portion of the stirrup streak 11.

At the site, the underground is excavated and the concrete 1 is thrown away. The U-shaped muscle 11B and the lower end main muscle 7 are horizontally arranged on it.

On the other hand, this cast concrete 1
The precast concrete plate 15 unitized in the factory is installed with the U-shaped streaks 11B and the like sandwiched therebetween. Also, by this time, stirrup muscle 11
An upper bar arrangement 19 in which the U-shaped bar 11C constituting the upper end and the upper end main bar 9 are grounded in advance is prepared. This upper bar arrangement 19
From above the installed precast concrete plate 15.

And, so to speak, the upper, middle and lower three parts 11A, 1
The substantially rectangular stirrup streak 11 is completed by constructing each part of the stirrup streak 11 divided into 1B and 11C into a lap joint structure. That is, U at the upper and lower ends of the stirrup streak 11
The type reinforcements 11C and 11B and the vertical reinforcement 11A form a lap joint 21. Therefore, the tips of the U-shaped muscles 11B and 11C and the longitudinal muscle 1
1A is overlapped with a certain size in the vertical direction.

A formwork 17 for supporting the floor slab 5 of the building from below is attached to the upper end of the precast concrete plate 15. After the reinforcing work and the building work are completed in this way, concrete 23 is poured. When the cast concrete 23 hardens, the underground wall 3 and floor slab 5
Are integrated and constructed.

As described above, according to this embodiment,
Since the unitized precast concrete boards 15 are joined to each other at the factory by the spacing bars 13, it is not necessary to connect them with a separator as in the conventional case on site. In other words, the spacing retaining bar 13 can sufficiently prevent the precast concrete plate 15 from falling outward due to the lateral pressure of the cast concrete 23.

Further, since the spacing-retaining bar 13 is already reinforced at the factory and a part thereof is embedded in the precast concrete plate 15, it is not necessary to re-arrange at the site.

By dividing the stirrup bar 11 into, so to speak, upper, middle and lower three parts 11A, 11B and 11C, the U-shaped bar 11C constituting the upper end of the stirrup bar 11 and the upper end main bar 9 are preliminarily erected. Therefore, the work of arranging can be performed in parallel with other works, and the efficiency of the work of arranging can be improved. Therefore, it is possible to reduce troublesome work as compared with the conventional case where the stirrup reinforcement 11 and the spacing retention reinforcement 13 are arranged after the precast concrete plate 15 serving as the formwork is installed.

Further, by connecting the U-shaped reinforcements 11B and 11C of the upper and lower reinforcements of the stirrup reinforcement 11 and the longitudinal reinforcement 11A by the lap joint 21, the precast concrete plate 15 unitized for the work of connecting these reinforcements. Alternatively, it is not necessary to extend the vertical streaks from the lower end, and it is possible to improve the production efficiency of the precast concrete plate 15 and the work efficiency on site.

In the above-mentioned embodiment (FIGS. 1 and 2), the space retaining ribs 13 are the two precast concrete plates 1
Although the truss muscle is arranged in a zigzag manner between 5 in the vertical direction, it may be a spiral muscle 25 as shown in FIGS. 3 to 5 in other embodiments. In the present embodiment, the spiral streak 25 is repeatedly drawn in a substantially closed shape in the horizontal plane, and is arranged in a spiral shape in the vertical direction. Of these, FIG. 3 shows a figure 8 shape. By using the figure-8 spiral reinforcement 25, each rebar that appears as if a large number of reinforcements were arranged between the two precast concrete plates 15 is not only inclined vertically but also in the plane. Therefore, it is possible to improve the rigidity with respect to a force that shifts the precast concrete plates 15 from each other in the vertical and horizontal directions.

Further, as shown in FIG. 4, it may be formed in a rectangular shape. Further, as shown in FIG. 5, it may have a triangular shape.

By thus forming the space-retaining bar 13 as the spiral bar 25, when the precast concrete plate 15 unitized in the factory is manufactured, the bar arrangement work is easy and the manufacturing efficiency can be improved.

[0025]

As described above, according to the method of constructing an underground girder of the present invention, the upper end of the underground girder is integrated with the building, and the lower end main bar and the upper end main bar are arranged at the lower end and the upper end. In the construction method of the underground beam constructed by arranging the stirrup between the lower and upper main reinforcements, the vertical reinforcement that constitutes the vertical part of the stirrup reinforcement is buried, Two precast concrete plates that form both sides and serve as a formwork are united by preliminarily joining them to each other with a predetermined spacing maintained by a space-retaining bar. A U-shaped bar, around which the main bar is wound to form the lower end of the stirrup bar, is arranged, then the unitized precast concrete plate is installed on this discarded concrete, and then the U-shaped bar that constitutes the upper end of the stirrup bar is installed. Type A precast concrete plate with the upper end main bar pre-assembled is covered from above, and the U-shaped bar and the vertical bar at the upper and lower ends of the stirrup bar are made into a lap joint structure, and then the unitized precast concrete plate is built. Since the formwork on the side was attached and the concrete was placed at the end, the two precast concrete plates would be integrally joined to each other beforehand with the gap-retaining bar. There is no need to do it.

Further, the stirrup bar is divided into upper, middle and lower parts, and the vertical stirrup constituting the vertical part is embedded in advance in the unitized precast concrete plate, and further the upper end of the stirrup bar is constituted. By arranging the U-shaped bar and the upper end main bar in advance, it is sufficient to simply arrange the upper, middle and lower parts of the bar arrangement work at the site, and the work can be reduced. Moreover, by using the lap joint, it is not necessary to take out the reinforcing bars from the upper and lower ends of the precast concrete plate for the work of joining the reinforcing bars, the precast concrete plate can be efficiently manufactured, and the workability on site is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic exploded perspective view of FIG.

FIG. 3 is a perspective view showing a first example in which a space holding muscle in FIG. 2 is a spiral muscle.

FIG. 4 is a perspective view showing a second example in which the space holding muscle in FIG. 2 is a spiral muscle.

FIG. 5 is a perspective view showing a third example in which the space holding muscle in FIG. 2 is a spiral muscle.

[Explanation of symbols]

 1 Discarded concrete 3 Underground beam 5 Floor slab 7 Bottom main bar 9 Top main bar 11 Stirrup bar 11A Longitudinal bar 11B, 11C U-shaped bar 13 Spacing bar 15 Precast concrete plate 17 Form 18 Reinforcing bar 19 Upper bar 21 Overlap joint 23 Concrete 25 spiral muscle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Haishi 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo headquarters (72) Inventor Tamura Etsunori 2-chome, Kandaji-cho, Chiyoda-ku, Tokyo Address Incorporated company Obayashi Tokyo Headquarters (72) Inventor Tatsuya Wakisaka 4-640 Shimoseido, Kiyose City, Tokyo Inside Obayashi Technical Research Institute Co., Ltd. (72) Noriyuki Furuya 4-640 Shimoseido, Kiyose City Tokyo (72) Inventor Kohei Kurita 4-640 Shimoseido, Kiyose-shi, Tokyo Obayashi Corporation Technical Research Institute

Claims (2)

[Claims] 1. An upper end of an underground beam is integrated with a building, a lower end main bar and an upper end main bar are arranged at the lower end and the upper end, and a stirrup bar is arranged between the lower end main bar and the upper end main bar. In the construction method of the underground beam to be constructed by building the vertical bar that constitutes the vertical part of the stirrup bar,
Two precast concrete plates, which form both sides of the underground beam and serve as a formwork, are integrally joined to each other with a predetermined spacing by a spacing-retaining bar in advance to form a unit. A U-shaped bar, which constitutes the lower end of the stirrup bar with the lower end main bar wound around it, is placed on the upper part of the stirrup concrete, and then the unitized precast concrete plate is installed on the discarded concrete. The U-shaped reinforcement and the upper-end main reinforcement that compose the above are ground in advance from above to the unitized precast concrete plate, and the U-shaped reinforcement and the vertical reinforcement at the upper and lower ends of the stirrup reinforcement are formed into a lap joint structure, and then the unit Construction method of underground girder characterized by mounting formwork on the building side to the converted precast concrete board and finally placing concrete 2. The method for constructing an underground girder according to claim 1, wherein the space retaining bar is a truss bar or a spiral bar.