JPH0244974B2 - UGATAHANKISEIKONKURIITOHARINOSEIZOYOCHIKATAWAKU - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inner formwork for manufacturing a semi-prefabricated concrete beam having a U-shaped cross-sectional shape and having a kotsuta formed on its inner surface.

[Conventional technology]

Semi-prefabricated concrete beams can reduce form work and almost eliminate shoring, so
It is attracting attention as a method that can reduce construction costs and shorten the construction period. In particular, embankments with a U-shaped cross-section have been proposed because they reduce the weight of the unit and can improve the efficiency of work such as lifting and installation on site. In order to make such a U-shaped semi-prefabricated concrete beam not only function as a formwork, but also to be structurally integrated with concrete cast on site, the overall size of the beam can be made more compact and costs can be reduced. The joint between the semi-prefabricated concrete section and the cast-in-place concrete section must be able to adequately transmit shear forces.

On the other hand, so-called shear connectors that transmit shear force include those in which reinforcing bars, bolts, etc. are appropriately protruded, and those in which a wire mesh or the like is interposed. in general,
In semi-prefabricated concrete products, a kotsuta formed in an uneven shape is often used as a shear connector on the joint surface with the concrete to be poured on site.
A U-shaped semi-prefabricated concrete beam with grooves formed on its inner surface has also been proposed.

[Problem that the invention seeks to solve]

However, U-shaped semi-prefabricated concrete beams with grooves formed on their inner surfaces have not yet been manufactured with good workability due to the following problems. In other words, when demolding the inner formwork used to form the kotsuta on the inner surface, the inner formwork cannot be pulled upward as it is, as is generally the case when creating a U-shaped groove. For example, when creating a kotsuta with unevenness arranged in a checkered pattern, first move the inner form in a direction substantially perpendicular to the inner surface, and then move it above the height of the kotsuta's unevenness. It is necessary to raise it to This is because it is difficult to properly remove the inner mold that forms the kotsuta.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to provide an inner formwork with which a U-shaped semi-prefabricated concrete beam having a groove formed on the inner surface can be fabricated with good workability.

[Means for solving problems]

The characteristic structure of the inner formwork for manufacturing a U-shaped semi-prefabricated concrete beam according to the present invention is that a pair of weir plates each having a convex portion formed on the surface are erected facing each other with each convex portion facing outward. The lower ends of these compatible weir plates,
The structure is fixed in position to form a gap having a width larger than the height of the convex portion, and a band-shaped weir plate that closes the gap is connected and fixed to the compatible weir plate.

[Effect]

In other words, since the pair of upright weir plates and the band-shaped weir plate for forming the kotsuta on the inner surface of the U-shaped semi-prefabricated concrete beam are constructed separately, the inner mold made of each of these weir plates is When removing the frame,
First, by removing the band-shaped weir plate, it is possible to move the compatible weir plate in a direction approximately perpendicular to the inner surface of the beam, using the gap that the band-shaped weir plate was blocking. By positioning the lower edge of the standing weir plate in the gap that is larger than the height of the convex part formed on the weir plate, it is possible to completely remove the standing weir plate from the inner surface of the semi-prefabricated concrete beam. It can be done.

〔Effect of the invention〕

As a result, the inner formwork, which tends to be difficult to demold due to the increased adhesion area with concrete, can now be easily demolded and removed. In addition, even if the kotta is formed by arranging unevenness in a checkered pattern, for example, the convex part of the standing weir plate can be completely extracted from the concave part of the kotsuta, so the standing weir plate can be pulled up extremely easily. Now I can do it.

Therefore, as a whole, it has become possible to create a U-shaped semi-prefabricated concrete beam with a groove formed on the inner surface with good workability.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a cross section of a formwork for manufacturing a U-shaped semi-fabricated concrete beam according to the invention. This formwork consists of an inner formwork S _I and an outer formwork S _O , and the inner formwork S _I
consists of a pair of standing weir plates 1 made of steel plates and a band-shaped weir plate 2 located between their lower edges 1a.

The compatible weir board 1 has a plurality of protrusions 3 on the outer side of the inner formwork S _I , respectively, for forming a kotsuta on the inner side of the U-shaped semi-prefabricated concrete beam. . The convex portions 3 are made by cutting and welding flat bars, and are arranged in a checkered pattern when viewed from the front, as shown in FIG. 4. And this inner formwork S _I
The checkerboard-shaped kotsuta formed on both inner surfaces of the U-shaped semi-prefabricated concrete beam manufactured using the U-shaped semi-prefabricated concrete beam transmits shear force in both the vertical and horizontal directions at the joint surface with the concrete poured on-site, over a wide area. This allows for effective communication. On the surface opposite to the surface having the convex portion 3, flat bars are welded at appropriate locations in the longitudinal direction to form vertical ribs 4,
A flat bar is welded between adjacent vertical ribs 4 to form horizontal ribs 5a and 5b.

In addition, the lower edge 1a of the compatible weir plate 1 is bent approximately at right angles to the rising portions of the weir plate 1, and the lower surface of this lower end 1a has a
A plurality of rib-like protrusions 6 are formed along the longitudinal direction of each of the protrusions. And the lower edge 1 of both weir plates 1
a are located so as to form a gap having a width L larger than the height l of the checkered convex portion 3 described above, and the band-shaped weir plate 2 is provided so as to close this gap.

On the lower surface in the longitudinal direction of the strip-shaped weir plate 2, a compatible weir plate 1 is installed.
A protrusion 7 is formed at a position corresponding to the rib-like protrusion 6 formed on the lower edge 1a of the U-shaped semi-prefabricated concrete beam. , unevenness is formed. 8 in the figure is an angle steel for reinforcement.
Further, 19 and 20 are reinforcing bars buried in the U-shaped semi-prefabricated concrete beam.

As shown in Figs. 1 to 3, the band-shaped weir plate 2
A plurality of columns 9 are erected at appropriate positions in the longitudinal direction, and a reinforcing member 10 made of angle steel is provided to connect the upper ends of each column 9. This reinforcing member 10 and the horizontal rib 5 at the upper end of the compatible weir plate 1
a are fixed to the formwork attachment member 11 at multiple locations in the longitudinal direction of the weir plate 1. In addition, members 12 having holes 12a penetrating in the vertical direction are welded and fixed to the lower edge 1a of the compatible weir plate 1 so as to face each other. On the other hand, a pair of pin-shaped members 1 engage with each of the holes 12a located at opposing positions.
3 is attached to the band-shaped weir plate 2, and the compatible weir plate 1 and the band-shaped weir plate 2 are connected and fixed by an engaging portion F consisting of a hole 12a and a pin-shaped member 13.

The engaging portions F are provided at a plurality of locations along the longitudinal direction of the inner formwork S _I. Furthermore, a protrusion 14 is formed at the tip of the protrusion 7 on the lower surface of the band-shaped weir plate 2 where the pin-shaped member 13 is attached, and the bottom of the recess 22 on the inner bottom of the U-shaped semi-prefabricated concrete beam B. A hole H is formed in the hole H.

This hole H is used when removing the inner formwork S _I after manufacturing the U-shaped semi-prefabricated concrete beam B. That is, when demolding the inner formwork S _I , first, the formwork attachment member 11 is removed, and then the band-shaped weir plate 2 is pulled upward together with the supports 9 and the like. Thereafter, as shown in FIGS. 5A and 5B, each compatible weir plate 1 is demolded from the concrete surface using a demolding tool 15.

The demolding tool 15 has a pin 17 coaxial with the rod 16 and an eccentric pin 18 fixed at different heights to the lower end of the rod 16. Then, as shown in Fig. 5A, insert the rod 16 and the tip of the concentric pin 17 into the hole H formed in the concrete bottom inside the beam, and insert the rod 16 and one tip of the eccentric pin 18. It is inserted into the hole 12a provided in the lower edge 1a of the standing weir plate 1.

In this state, as shown in FIG.
By swinging the upper end of the weir plate 6 to the left in the figure, the lower side of the erected weir plate 1 can be released from the concrete surface. Next, the upper side of the standing weir plate 1,
By releasing the mold from the concrete surface using a tool such as a crowbar and performing the above-mentioned operations sequentially along the longitudinal direction of this inner formwork S _I , it is possible to remove the entire one standing weir plate 1 from the mold. It can be done.

At this time, as explained earlier, the compatible weir plate 1
The lower edges 1a of the dam plates 1a are located so as to form a gap with a width L larger than the height 1 of the convex portion 3 formed on the surface of the erected dam plate 1, and this gap, which was previously blocked by the band-shaped dam plate 2, is located. Using the gap, install one of the standing weir plates 1,
It can be moved in a direction substantially perpendicular to that direction. Then, with the lower edge 1a of this erected weir plate 1 located in the above-mentioned gap, the convex portion 3 formed on the surface of the erected weir plate 1 was formed on the inner surface of the U-shaped semi-prefabricated concrete beam B. It can be completely pulled out from the recess 21 of the cotter C, and the standing weir plate 1 can be easily pulled upward. The other standing weir plate 1 can also be demolded by the same procedure as described above.

Next, a process of manufacturing a U-shaped semi-prefabricated concrete beam using the inner diameter frame S _I according to the present invention will be described.

First, as shown in Figure 6A, an outer formwork S _O consisting of three dam plates is assembled. Next, as shown in FIG. 6B, main reinforcing bars 19 and stirrups 20 are arranged inside this outer formwork _SO . Then, as shown in FIG. 6C, the outer formwork _SO is bolted to the member 11 to which the inner formwork S _I described earlier was fixed with bolts. After that, as shown in Figure 6 D, this inner formwork is
Concrete is poured and cured between S _I and outer formwork S _O.

After that, for example, after four weeks, the inner formwork S _I
When demolding the outer formwork S _{O and the outer formwork S O} , first, the formwork attachment member 11 is removed, and then the band-shaped weir plate 2 of the inner formwork S _I is removed. In this state, as shown in FIGS. 5A and 5B, the compatible weir plate 1 of the inner formwork S _I is demolded and removed using the demolding tool 15. Thereafter, the outer formwork _SO is also demolded to obtain a U-shaped semi-prefabricated concrete beam B having a U-shaped cross section and a ridge C formed on its inner surface, as shown in FIG. 6F.

In carrying out the present invention, the shape of the cotter C can be changed as appropriate; for example, instead of the checkered pattern described in the previous embodiment, it may be rib-shaped or bird-shaped. and accordingly,
The shape and arrangement of the protrusions 3 formed on the surface of the standing weir plate 1 can be changed as appropriate.

[Brief explanation of drawings]

The drawings show an embodiment of the inner formwork for manufacturing a U-shaped semi-prefabricated concrete beam according to the present invention, and FIG. 1 is a sectional view of the formwork for manufacturing a U-shaped semi-prefabricated concrete beam,
The figure is a plan view of the inner formwork, Fig. 3 is a partially cutaway perspective view of the inner formwork, Fig. 4 is a partially enlarged perspective view of the inner formwork, and Fig. 5 is a partially cutaway perspective view of the inner formwork.
Figures A and B are cross-sectional views showing the process of demolding the inner formwork;
Figures 6A to 6F are cross-sectional views showing the manufacturing process of a U-shaped semi-prefabricated concrete beam. DESCRIPTION OF SYMBOLS 1... Standing weir plate, 2... Band-shaped weir plate, 3... Convex part, 12a... Hole, 13... Pin-shaped member, 14...
...Protrusion, B...U-shaped semi-prefabricated concrete beam, C...
...Kotta.

Claims (1)

[Scope of Claims] 1. A pair of inner forms for manufacturing a semi-prefabricated concrete beam B having a U-shaped cross-sectional shape and having a ridge C formed on its inner surface, the inner formwork having a convex portion 3 formed on its surface. Weir plates 1 are erected facing each other with their respective protrusions 3 facing outward, and the lower edges 1a of these erected weir plates 1 are separated by a width L larger than the height l of the protrusions 3. This inner formwork for manufacturing a U-shaped semi-prefabricated concrete beam is fixed in position to form a gap, and a band-shaped weir plate 2 that closes the gap is connected and fixed to a compatible weir plate 1. 2. The means for connecting and fixing the coexisting weir plate 1 and the band-shaped weir plate 2 is a plurality of pairs of holes 12a that penetrate in the vertical direction and are formed at a plurality of locations facing each other on the lower edge 1a of the coexistence weir plate 1; A pin-shaped member 1 formed on the band-shaped weir plate 2 so as to engage with each hole 12a.
3, and the belt-shaped weir plate 2 has a protrusion 14 on the lower surface of the portion where the pin-shaped member 13 is formed. Internal formwork. 3. For manufacturing a U-shaped semi-prefabricated concrete beam according to claim 1 or 2, wherein the convex portions 3 are arranged in a checkerboard pattern with respect to each standing weir plate 1. Formwork.