JPH06322816A - Precast concrete form - Google Patents

Abstract

PURPOSE:To form a slit part, prevent damage, etc., caused by deterioration in strength in a part and impove reliability. CONSTITUTION:On a side face 1A of a precast concrete member 1 having a concrete 7 and a reinforcing ber 5 buried inside and forming a cylindrical state, a slit part 4A in which the reinforcing bar 5 is exposed is formed in advance at bardening of the concrete 7. At least between concrete on both sides of the slit part 4A, a shape holding bar 6 is provided apart from the reinforcing bar 5. As the slit part 4A is formed in advance in hardening of the concrete 7, later chipping is not needed, and as the shape holding bar 6 is provided between the concrete on both sides of the slip part 4A apart from the reinforcing bar 5, strength is further improved by this shape holding bar 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast concrete formwork for forming a column in which a reinforcing bar is embedded in a tubular concrete, and more specifically, it has a slit part for joining with a wall part. Precast concrete formwork.

[0002]

2. Description of the Related Art Conventionally, for the purpose of improving work efficiency, etc., a precast concrete formwork (fume box) in which reinforcing bars are embedded in a tubular concrete is previously prepared in a factory by a well-known centrifugal molding method. After manufacturing, the precast concrete formwork is used as a formwork at a predetermined position on the construction site to form a pillar by pouring cast-in-place concrete into it, a so-called half precast method is applied to the pillar. Has been adopted. In the above-mentioned construction method, when the wall portion is cast on the side surface portion of the precast concrete formwork, the side surface portion is provided with an open precast concrete formwork, and the cast-in-place concrete is placed inside the precast concrete formwork. After pouring and hardening of this cast-in-place concrete, a slit part where the reinforcing bar is exposed is formed by attaching the wall casting part on the side of the precast concrete formwork, and then this slit The wall part is placed including the part. However, the above-mentioned precast concrete formwork has a problem that cracking may occur during the chipping work. For this reason, a precast concrete formwork is being adopted in which the slit portion where the reinforcing bar is exposed is formed in advance at the time of molding in the factory (that is, at the time of concrete hardening) at the wall portion driving portion of the side surface portion. .

[0003]

In the precast concrete formwork in which the slits are formed in advance as described above, there is a problem in that the slits are composed of only reinforcing bars, so that the strength thereof is insufficient.

Therefore, an object of the present invention is to provide a precast concrete formwork in which the strength is not insufficient even when the slit portion is formed in advance.

[0005]

In order to achieve the above object, the precast concrete formwork of the present invention is one in which a reinforcing bar is embedded in a concrete having a tubular shape, and the side wall portion has the above-mentioned structure. It is characterized in that a slit portion in which the reinforcing bar is exposed is formed, and a shape-reinforcing bar is provided separately from the reinforcing bar at least between the concrete on both sides of the slit section.

[0006]

According to the precast concrete formwork of the present invention, the shape-reinforcing bar is provided separately from the reinforcing bar between the concrete on both sides of the slit formed on the side surface and in which the reinforcing bar is exposed. Therefore, the shape-retaining muscles increase the strength.

[0007]

EXAMPLE A precast concrete formwork (hereinafter referred to as a precast member) according to a first example of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the precast member 1 of the first embodiment has a rectangular tubular shape having four side surfaces 1A to 1D having a predetermined thickness so as to have a substantially square shape in a plan view. The side surface portions 1A to 1D are
Each has a thick portion 3 in the center and thin portions 2 and 2 on both sides of the thick portion 3 which are thinner than this. Here, the thick portion 3 at the center is formed for the purpose of obtaining sufficient strength against an impact load from the outside when handling the precast member 1 and a concrete pressure when placing concrete.

The precast member 1 is made of reinforced concrete and serves as a joint with a wall (not shown).
At a predetermined position of any of the side surface portions 1A to 1D, a slit portion made of only reinforcing bars is continuously formed over the entire range in the length direction. In addition, in the first embodiment, the slit portion 4A is provided in one thin portion 2 of the side surface portion 1A. Here, of the side surface portions 1A to 1D, the inner surface side of the corner portion formed by the boundary portion between adjacent ones is formed into a curved surface, that is, the R surface, and the outer surface side of the boundary portion between the adjacent ones is It has a flat chamfered shape. Of course, it is possible to make the inner surface of the corner flat and the outer surface R
It can also be a face.

As shown in FIG. 3, a portion of the reinforcing bar embedded in the concrete 7 appears in the slit portion 4A, and the reinforcing bar 5 has a rectangular tubular shape similar to that of the precast member 1, and the reinforcing bar 5. It has a shape-retaining band (shape-reinforcing bar) 6 which is formed into a square ring and is made of deformed rebar or the like, through which the reinforcing bar 5 is inserted. Here, the reinforcing bar 5 improves the strength of the entire precast member 1,
As will be described later, the shape-retaining stirrup 6 maintains the shape of the precast member 1 while maintaining the distance between the slit portions 4A. Reinforcing bars 5 are provided inside the entire length of the precast member 1, and a plurality of shape-retaining bands 6 are arranged in the length direction of the precast member 1 at a predetermined pitch in a state of being along the horizontal direction. There is. Note that the shape-retaining streak 6
The pitches near the upper end and the lower end, which require the highest strength, are closer to the pitch than the other portions.

Here, in the first embodiment, the reinforcing bar 5 is a lattice-shaped body in which small-diameter reinforcing bars are joined by spot welding at intersecting portions. A description will be given by taking as an example the one that is joined to form a rectangular tube. The reinforcing bars 5 have a lattice shape with a small vertical distance and a large horizontal distance. The shape-retaining bar 6 has a diameter larger than the reinforcing bar diameter of the reinforcing bar 5.

Although not shown, the precast member 1 has, for example, an outer mold having an inner shape substantially the same as the outer shape of the precast member 1 and an outer shape having substantially the same shape as the inner shape of the precast member 1. In a state where the reinforcing bar 5 and the shape-retaining band 6 are arranged in a space formed by the inner mold, concrete is filled in the space and centrifugal molding is performed to manufacture the factory. It has become. In addition, the outer die is formed with an outer die protruding portion projecting inward in a portion corresponding to the slit portion 4A continuously in the length direction of the precast member 1, and the inner die also has the slit portion 4A. Inner die protrusions that protrude outward are formed continuously at corresponding portions in the length direction of the precast member 1. Then, the tip end surfaces of the outer die protrusion and the inner die protrusion on the protruding sides are joined together while sandwiching the reinforcing bar 5 and the shape-retaining band 6.
Concrete is prevented from entering this portion, and the slit portion 4A composed of the reinforcing bar 5, that is, the reinforcing bar 5 and the shape-retaining band 6, is preliminarily formed continuously along the lengthwise direction during hardening of the concrete. In addition, in the slit portion 4A, for example, the reinforcing bar 5 and the shape-retaining bar 6 are interposed between the outer mold and the inner mold that do not have the protruding portion so that concrete does not enter the formation position of the slit portion 4A. A core may be provided and the core may be removed after the concrete is hardened.

Then, the precast member 1 having such a slit portion 4A formed in advance in the manufacturing plant is transported to the building site, the precast member 1 is installed at a predetermined position of the building site, and inside the precast member 1 the site is installed. Pour out concrete. Here, the precast member 1
After the molding, a lath K such as a metal plate fitted to the slit portion 4A is attached with a binding wire to the inside of the reinforcing bar 5 and the shape-retaining band bar 6 of the slit portion 4A, and this is used as a net form to make a concrete stop. To do. After the cast-in-place concrete is hardened, the wall portion is laid out including the slit portion 4A, the wall formwork is assembled, and then the concrete is placed. Before the cast-in-place concrete is poured into the pillar portion, a horizontal bar arrangement of the wall portion is inserted into a predetermined position of the slit portion 4A of the side surface portion 1A of the precast member 1 if necessary.

According to the precast member 1 of the first embodiment having such a structure, the slit portion 4A is formed in advance on the side surface portion 1A corresponding to the driving position of the wall portion at the time of hardening of the concrete. Therefore, it is not necessary to carry out chipping for connecting the walls, and it is possible to eliminate the occurrence of cracks and rattles. Besides, between the concrete 7 on both sides of the slit portion 4A, the shape-retaining bar 6 is provided separately from the reinforcing bar 5.
Since the shape-retaining stirrups 6 are provided, the strength is improved. Therefore, damage or the like due to the strength reduction of the slit portion 4A will not occur. Also,
The drainage of the cast-in-place concrete is satisfactorily performed from the lath K, that is, the slit portion 4A.

It is also possible to use, as the shape-retaining band, one that binds L-shaped muscles. Further, as shown in FIG. 4, it is also possible to provide the shape-retaining bar 6 inside the reinforcing bar 5, and with such arrangement, the unevenness on the surface side is eliminated and the reinforcing bar 5 is evenly arranged on the outer surface side. Since it is provided and molded, it is possible to further prevent cracks occurring on the surface of the precast member 1 due to the load when pouring concrete. Further, like the precast member 10 of the second embodiment shown in FIG. 5, two slit portions 11A, 11 are provided on the side surface portions 10A, 10C.
Of course, it is also possible to provide C or to provide the slit portions 16A, 16B, 16C at three places on the side surface portions 15A, 15B, 15C like the precast member 15 of the third embodiment shown in FIG.

Below, due to the difference in the number of slit portions of the precast members 1, 10 and 15 of the first to third embodiments,
The results of measuring the lateral pressure, the amount of strain, and the amount of flexure during cast-in-place concrete will be described. First, in each of the precast members 1, 10 and 15, the column width is 70 cm, the thin portion 2 has a thickness of 3 cm, the column height is 2.45 m, and the slit portion 4 is used.
Width W of A, 11A, 11C, 16A to 16C is 15 cm
And slit portions 4A, 11A, 11C, 16A to 16
A concrete lath is attached to C by mounting a lath (not shown) as in the case of the on-site construction. Here, there is no column clamp (concrete member reinforcing material) for clamping the reinforcement of the column reinforcing bars arranged in the precast members 1, 10 and 15 and the outside of the precast members 1, 10 and 15, and filling in-place concrete Is made of ready-mixed concrete, with a slump 18 cm and a hopper (capacity 1 m
Place by ³ ).

FIG. 7 shows each precast member 1, 10, 15
The specifications of. That is, the precast member 1 is
The age is 53 days, the number of slits is 1, and the reinforcing bar (mesh bar) and the hoop material of D10 (reinforcing bar pitch of 30 cm) are adopted as the reinforcing bar. 52 days, 2 slits,
The reinforcing bar (mesh bar) and the hoop material of D10 (bar arrangement pitch of 30 cm in the vertical direction) are adopted as the reinforcing bar. The precast member 15 has a material age of 49 days, the number of slits is 3, and the reinforcing bar. As the reinforcing bar (mesh bar) and the L-shaped bar of D10 are united (vertical bar arrangement pitch 30 cm).

Further, as shown in FIG. 2, at the end position of the slit portion 4A of the precast member 1 on the center side, the distance L ₁ from the adjacent one side surface portion 1B is 490 mm. Slit portions 11A, 11 of the precast member 10
As shown in FIG. 5, C is provided on the side surface portion 10A and the side surface portion 10C facing the side surface portion 10A, and any slit portions 11A and 11C are distances L ₁ and L ₂ from the adjacent one side surface portion 10B. Is 490 mm. As shown in FIG. 6, the slit portions 16A and 16C of the precast member 15 are provided on the side surface portion 15A and the side surface portion 15C facing the side surface portion 15A, and the slit portions 16A and 16C are adjacent to each other, as in the precast member 10. The distances L ₁ and L ₂ from the side surface portion 15B are set to 490 mm, and the slit portion 16B is located at the center position on the side surface portion 15B (that is, the distance L ₃ from the adjacent side surface portions 15A and 15C is 2).
75 mm).

The precast members 1 and 10 are
Are cast with cast-in-place concrete inside while vibrating with a high-frequency vibrator.
After pouring cast-in-place concrete on the inside, it was compacted with a high-frequency vibrator.

FIG. 8 shows the measurement positions of the precast member 1, FIG. 9 shows the precast member 10, and FIG. 10 shows the measurement positions of the precast member 15. Here, the strain amount measurement position measured by the strain gauge is indicated by "-", the deflection amount measurement position measured by the displacement gauge is indicated by "□", and the lateral pressure measurement position measured by the lateral pressure gauge is " It is shown by "○".

As shown in FIG. 8, the deflection amount of the precast member 1 is 200 mm (position A), 500 mm (position A), 7 from the bottom in the vicinity of the slit portion 4A of the side surface portion 1A.
50 mm (Position C), 1000 mm (Position D), 125
Each position of 0 mm (position E) and the side surface portion 1A of the side surface portion 1D
From the side, from the bottom, measurement is performed at the respective outer surface sides of 200 mm (position D), 500 mm (position D), 750 mm (position D), 1000 mm (position K), 1250 mm (position D). The strain amount of the precast member 1 is
On the side opposite to the slit portion 4A of the side surface portion 1A, from below,
200 mm (position), 500 mm (position), 750
mm (Position), 1000 mm (Position), 1250 m
From each position of m (position S) and the side surface 1C side of the side surface portion 1D, from the bottom, 200 mm (position position), 500 mm (position position), 750 mm (position position), 1000 mm (position position), 1250 mm (position) (G) Measured on the outer surface side of each position. The lateral pressure of the precast member 1 is measured on the inner surface side of the center of the lower end (position 0) of the side surface portion 1B.

As shown in FIG. 9, the precast member 10
The amount of deflection is 200 mm (position A), 500 mm (position A), 750 mm (position C), 1000 mm (position D), and 1250 mm (position E) from the bottom in the vicinity of the slit portion 11A of the side surface portion 10A. And the side part 10
In the vicinity of the slit portion 11C of C, from the bottom, 200 mm (position position), 500 mm (position position), 750 mm (position position), 1000 mm (position position), 1250 mm (position position) at the respective outer surface sides. taking measurement. The amount of strain of the precast member 10 is 200 mm (positioning), 500 mm (positioning), 750 mm (positioning) from the bottom on the side opposite to the slit portion 11A of the side surface portion 10A,
Each position of 1000 mm (Position), 1250 mm (Position S), and 200 mm (Position), 500 mm (Position), 750 mm (Position), from the opposite side to the slit portion 11C of the side surface portion 10C, from below. The measurement is performed on the outer surface side of each position of 1000 mm (position T) and 1250 mm (position G). The lateral pressure of the precast member 10 is measured on the inner surface side of the lower end center (position 0) of the side surface portion 10B.

As shown in FIG. 10, the precast member 1
The deflection amount of 5 is 200 mm (position A), 500 mm (position A), 750 mm (position C) from the bottom in the vicinity of the slit portion 16A of the side surface portion 15A and the side surface portion 15B.
200 mm (position D), 500 mm (position E), 750 mm (position D) near the slit portion 16B of
At each position of 1000 mm (position position) and in the vicinity of the slit portion 16C of the side surface part 15C, from the bottom, at each position of 200 mm (position position), 500 mm (position position), 750 mm (position position), on the outer surface side. taking measurement. The amount of strain of the precast member 15 is determined by the slit portion 16 of the side surface portion 15A.
200 mm from the bottom on the opposite side to A (position), 5
00 mm (Position), 750 mm (Position), 1000
mm (Position), 1250 mm (Position),
200 mm from below, on the side surface portion 15C side of the side surface portion 15B
(Position), 500 mm (Position), 750 mm (Position), 1000 mm (Position), 1250 mm (Position), and 200 mm from the opposite side to the slit portion 16C of the side surface portion 15C from the bottom. (Position), 500m
m (position d), 750 mm (position d), 1000 mm
(Position) and 1250 mm (Position) are measured on the outer surface side. The lateral pressure of the precast member 15 is measured on the inner surface side of the center of the lower end (position 0) of the side surface portion 15D.

The measurement was carried out at every casting height of 50 cm of cast-in-place concrete. Each precast member 1,1
FIG. 11 shows the pouring height with respect to the pouring time of 0, 15 cast-in-place concrete.

Then, in FIG. 12, each precast member 1,
The change of the lateral pressure with respect to the cast-in-place concrete pouring height of 10 and 15 is shown. Maximum lateral pressure is precast member 1,1
Both 0 and 15 are around 4.5 tf / m ² ,
No difference was observed depending on the number of slits. Further, although not shown in the drawing, the measured lateral pressure of the precast member having no slit portion is such that the caster height is 230 cm and the maximum lateral pressure is about 4.5 tf / m ² in both the column widths of 75 cm and 90 cm. It was found that there was no difference due to the size of the column width. In addition, the precast member 15 has a large lateral pressure up to the casting height of 150 cm with respect to the precast members 1 and 10, which makes the casting speed of the cast-in-place concrete very fast as shown in FIG. Therefore, the impact pressure was exerted, and the fact that only the precast member 15 did not use a vibrator during cast-in-place concrete casting caused little water drainage (pressure loss) from the slit portions 16A to 16C. it seems to do.

FIG. 13 shows changes in the amount of deflection of the precast member 1 with respect to the height of cast-in-place concrete.
Here, the casting speed of cast-in-place concrete is 24.9 m ³ / hr when the driving height is between 0 and 230 cm, and the average casting height per hour is 60.9 m / hr. The maximum amount of deflection is 4.67 mm, and it can be seen that the portion is bent like a cantilever from the corner formed by the side surface portion 1A and the side surface portion 1B.

FIG. 14 shows changes in the amount of strain of the precast member 1 with respect to the height of cast-in-place concrete.
All strain values are on the compression side, and it can be seen that a moment similar to the corner of the box frame is generated. In this case, it is considered that the shape-retaining stirrup 6 is also involved in the reinforcement.

FIG. 15 shows changes in the amount of deflection of the precast member 10 with respect to the height of cast-in-place concrete. Here, the casting speed of cast-in-place concrete is 33.9 m ³ / h when the driving height is between 0 and 230 cm.
The average casting height per hour is 82.8 m / hr. The maximum amount of deflection is 5.81 mm.

FIG. 16 shows changes in the amount of strain of the precast member 10 with respect to the height of cast-in-place concrete. All strain values are on the compression side.

FIG. 17 shows the change of the lateral pressure with respect to the elapsed time of the precast member 10, and FIG.
19 shows the change in the amount of deflection with respect to the elapsed time, and FIG. 19 shows the change in the amount of strain with time of the precast member 10.
Although shown respectively, it can be seen that all the measured values become smaller over time. In particular, the lateral pressure showed a maximum lateral pressure of 4.7 tf / m ² at the end of the driving, but after 1 hour, it became 1.85 tf / m ^{2 and} decreased by about 60%. It is considered that this is due to water leakage (pressure leakage) from the slit portions 11A and 11C.

FIG. 20 shows changes in the amount of deflection of the precast member 15 with respect to the height of cast-in-place concrete. Here, the casting speed of cast-in-place concrete is 116.9 m ³ / h when the driving height is between 0 and 230 cm.
r, the average casting height per hour is 285.5 m / hr, and the casting is performed under extremely severe conditions. Maximum deflection is 7.3
mm, the side surface portion 15B having a slit portion 16B in the center
There was almost no deflection. It is considered that this is because the slit portion 16B originally exists at the position where the maximum moment is generated, so that the moment does not occur here and the slit-like function is provided.

The precast member 15 is shown in FIGS.
The change of the amount of strain with respect to the height of cast-in-place concrete is shown. All strain values are on the compression side.

From the above measurement results, the lateral pressure of cast-in-place concrete is determined by the slit portions 4A, 11A, 11C and 16A.
It can be seen that the same change in lateral pressure is exhibited regardless of the presence or absence of 16C and the number thereof. In addition, the slit portions 4A, 11A,
It can be seen that since the water leakage from 11C and 16A to 16C is very large, the cast-in-place concrete lateral pressure is reduced by about 60% one hour after the completion of the casting. Further, although the precast member 15 used is one in which L-shaped muscles are bound and processed into a hoop shape, it can be seen that there is no difference from the integral shape retaining strap used in the precast members 1 and 10. In addition, slit parts 4A, 11A, 11C, 16A-16
Since the side pressure is reduced due to the water leakage from C, it can be seen that the method of controlling the side pressure by the driving speed is effective.

Here, the precast members 1, 10,
In order to further increase the rigidity of the column with wall using 15, it is possible to reduce the pitch of the shape-retaining band reinforcements 6.
Further, the slit portions 4A, 11A, 11C, 16A to 16C
It is also possible to dispose them as horizontal connecting portions of concrete intermittently at regular intervals, instead of being arranged continuously in the vertical direction, but it is more cost effective to provide them continuously. In addition, by casting the cast-in-place concrete several times, or by slowing the casting speed and utilizing the side pressure reducing effect from the laths, that is, the slit portions 4A, 11A, 11C, 16A to 16C. It is possible to effectively reduce the occurrence of cracks in the precast members 1, 10 and 15. Although it is possible to reinforce the precast members 1, 10 and 15 with a separator, those who do not use the precast members 1, 10 and 15 may be unexpectedly cracked by making holes. Is preferred.

In the above description, as the mesh form K, a punched wire mesh or a metal lath, such as expanded metal, which is formed by punching thin steel plates at regular intervals by punching and stretching the slits to form a mesh, is adopted. However, it is also possible to employ a welded mesh in which the assembled contacts are electrically welded in a grid pattern such as an iron wire to form a mesh, that is, a welded wire mesh or the like.

Further, when the reinforcing bar 5 in which iron wires or the like are assembled in a grid form and the contacts are electrically welded to form a net-shaped reinforcing bar 5 is formed into a rectangular tubular shape, a plurality of vertical bars are arranged in a rectangular shape in plan view. A plurality of angular ring-shaped strips may be welded and fixed vertically on the outer periphery of the vertical strips at a predetermined pitch. Alternatively, it is possible to spirally spirally stir the outer circumference of the vertical streaks so as to shift the positions vertically and weld and fix the spiral streaks. And, the arrangement pitch of the strap or the winding pitch of the spiral muscle,
A large pressure is generated when the cast-in-place concrete is placed inside by making the pitch of the lower part smaller than the upper part or making the lower part double at the lower end. The strength of the part can be increased. Further, it is possible to provide auxiliary muscles in parallel with the longitudinal muscles in the vicinity of the longitudinal muscles located at the four corners. In addition, since the reinforcing bar 5 is apt to be impacted at the upper and lower ends when handling the reinforcing bar 5, the upper and lower ends can be double wound to reinforce this part.

In the above description, the shape-retaining bar 6 is a square ring-shaped member made of deformed rebar or the like and is provided on the outside or inside of the reinforcing bar 5 over the entire circumference. If the main purpose is to maintain the positional relationship between the two, then at least between the concrete on both sides of the slit part where the reinforcing bar is exposed, at least one of the inside and the outside of it is provided with the shape-reinforcing bar. The shape-retaining muscle can be variously changed according to the position of the slit portion and the like.

For example, as in the precast member 17 of the fourth embodiment shown in FIG. 24, slit portions 18B and 18D are provided in the thin portion 2 on the side surface portion 17C and the side surface portion 17C facing the side surface portion 17D. When provided, the side wall portion 17A passes through the side wall portions 17B, 17C, 17D from substantially the center of the thin wall portion 2 on the side wall portion 17B side.
As shown in FIG. 25, the shape-retaining bar 19 extending to approximately the center of the thin portion 2 on the side portion 17D side of A or the thickness of the side portion 17C from the substantially center of the thin portion 2 on the side portion 17A side of the side portion 17B. The shape-retaining bar 20B extending to the side surface portion 17B side of the meat portion 3 and another side surface portion 1 of the thick portion 3 of the side surface portion 17C from the approximate center of the thin portion 2 on the side surface portion 17A side of the side surface portion 17D.
The shape-retaining muscle 20D extending to the 7D side, or the same as above,
As shown in FIG. 26, it is also possible to make the shape-retaining muscle 21 closed in a square ring shape.

Further, like the precast member 22 of the fifth embodiment shown in FIG. 27, the slit portion 23A is provided in the thin portion 2 on the side surface portion 22B side of the side surface portion 22A, and the thin portion on the side surface portion 22C side of the side surface portion 22D. 2 is provided with slit portions 23D, the side surface portion 22B passes through the side surface portions 22A and 22D from the side surface portion 22A side of the thick portion 3 of the side surface portion 22B.
Conformator 24 extending to the side surface 22D side of the thick portion 3 of 2C
Alternatively, as shown in FIG. 28, a shape-retaining bar 25A extending from the side surface portion 22A side of the thick portion 3 of the side surface portion 22B to a position beyond the thick portion 3 of the side surface portion 22A, and another
Shape-reinforcing bar 25D extending from the side surface 22D side of the thick portion 3 of the side surface portion 22C to a position beyond the thick portion 3 of the side surface portion 22D.
It is also possible to use the shape-retaining bar 26 closed in the shape of a square ring, as shown in FIG. 29, as described above.

Further, as in the precast member 28 of the sixth embodiment shown in FIG. 30, the slit portion 29A is formed in the thick portion 3 of the side surface portion 28A, and the slit portion 29A is formed in the thick portion 3 of the side surface portion 28C facing the slit portion 29A. When 29C is respectively provided, the side wall portion 2 of the thick wall portion 3 of the side wall portion 28D passes through the side wall portion 28A from the side wall portion 28A side of the thick wall portion 3 of the side wall portion 28B.
Shape-retaining muscle 30A extending to the 8A side, and other than this,
From the side surface portion 28C side of the thick portion 3 of the side surface portion 28B to the side surface portion 2
8C to form a shape-retaining bar 30C that extends to the side surface portion 28C side of the thick portion 3 of the side surface portion 28D, or as shown in FIG. The side surface portion 28A of the side surface portion 28D passing through the portion 28A
Side shape portion 31A extending to approximately the center of the thin portion 2 on the side, and another side portion of the side surface portion 28C that passes through the side surface portion 28C from substantially the center of the thin portion 2 on the side surface portion 28C side of the side surface portion 28B. Shape-retaining bar 31 extending to approximately the center of the thin portion 2 on the 28C side
It is also possible to set it as C, or as in the above, as shown in FIG.

In addition, it is also possible to form the shape-retaining bar by a spiral bar which is spirally wound around the reinforcing bar so as to gradually shift its position vertically. In addition, as for the shape-retaining bar, only the part where strength is particularly required (for example, the lower part where the pressure of cast-in-place concrete is high) is partially reduced as described above, or the diameter is increased. Is also possible. The shape-retaining bar may be provided outside the reinforcing bar, inside the reinforcing bar, or may be provided with only a predetermined part on the outside and other parts on the inside. Furthermore, the shape of the precast member and the reinforcing bars embedded therein is not limited to the above-described square tube shape,
It may be of various polygonal shapes such as an octagonal shape, or of course, a cylindrical shape. It is also possible to make multiple reinforcing bars.

[0041]

As described above in detail, according to the precast concrete formwork of the present invention, since the shape-reinforcing bar is provided separately from the reinforcing bar at least between the concrete on both sides of the slit portion, The shape-retaining bar improves the strength, and the shape is maintained with sufficient construction accuracy. Therefore, even if the slit portion is formed, excessive bending or damage due to the decrease in strength of this portion does not occur, reliability is improved and construction accuracy is good, and therefore construction quality can be improved. To be

[Brief description of drawings]

FIG. 1 is a perspective view showing a precast concrete formwork according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a precast concrete formwork according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing an example in which a part of the slit portion of the precast concrete formwork according to the first embodiment of the present invention is enlarged.

FIG. 4 is a perspective view showing another example in which a part of the slit portion of the precast concrete formwork according to the first embodiment of the present invention is enlarged.

FIG. 5 is a plan view showing a precast concrete formwork according to a second embodiment of the present invention.

FIG. 6 is a plan view showing a precast concrete formwork according to a third embodiment of the present invention.

FIG. 7 is a table showing specifications of precast concrete formwork according to the first to third examples of the present invention at the time of a cast-in-place concrete placing test.

FIG. 8 is a diagram showing respective measurement positions of lateral pressure, strain amount, and deflection amount in a cast-in-place concrete placing test of the precast concrete formwork according to the first example of the present invention.

FIG. 9 is a diagram showing respective measurement positions of lateral pressure, strain amount, and deflection amount of a precast concrete formwork according to a second embodiment of the present invention at the time of cast-in-place concrete placing test.

FIG. 10 is a diagram showing measurement positions of lateral pressure, strain amount, and deflection amount of a precast concrete formwork according to a third embodiment of the present invention during a cast-in-place concrete placing test.

FIG. 11 is a characteristic diagram showing changes in the pouring height with respect to the pouring time of concrete in the test for pouring concrete on site, in the precast concrete formwork according to the first to third examples of the present invention.

FIG. 12 is a characteristic diagram showing changes in lateral pressure with respect to the concrete pouring height in the precast concrete pouring test of the precast concrete formwork according to the first to third examples of the present invention.

FIG. 13 is a characteristic diagram showing changes in the amount of deflection of the precast concrete formwork according to the first example of the present invention with respect to the concrete pouring height during a test for in-place pouring of concrete.

FIG. 14 is a characteristic diagram showing a change in strain amount with respect to a concrete pouring height in a cast-in-place concrete pouring test of the precast concrete formwork according to the first example of the present invention.

FIG. 15 shows changes in the amount of deflection of a precast concrete formwork according to a second example of the present invention with respect to the concrete pouring height during a test for in-place concrete pouring.

FIG. 16 is a characteristic diagram showing changes in the amount of strain with respect to the concrete pouring height in the cast-in-place concrete pouring test of the precast concrete formwork according to the second example of the present invention.

FIG. 17 is a characteristic diagram showing changes in lateral pressure of a precast concrete formwork according to a second example of the present invention with respect to elapsed time during a cast-in-place concrete placing test.

FIG. 18 is a characteristic diagram showing changes in the amount of deflection of the precast concrete formwork according to the second example of the present invention with respect to the elapsed time during a cast-in-place concrete placing test.

FIG. 19 is a characteristic diagram showing changes in the amount of strain with time in a cast-in-place concrete placing test of a precast concrete formwork according to a second example of the present invention.

FIG. 20 is a characteristic diagram showing the change in the amount of deflection of the precast concrete formwork according to the third example of the present invention with respect to the concrete pouring height during a test for in-place pouring of concrete.

FIG. 21 is a characteristic diagram showing a part of the change in strain amount with respect to the concrete pouring height in the cast-in-place concrete pouring test of the precast concrete formwork according to the third example of the present invention.

FIG. 22 is a characteristic diagram showing another part of the change in strain amount with respect to the concrete pouring height in the cast-in-place concrete pouring test of the precast concrete formwork according to the third example of the present invention.

FIG. 23 is a characteristic diagram showing yet another portion of the change in strain amount with respect to the concrete pouring height in the precast concrete pouring test of the precast concrete formwork according to the third example of the present invention.

FIG. 24 is a plan sectional view showing an example of the shape-retaining bar of the precast concrete formwork according to the fourth embodiment of the present invention.

FIG. 25 is a plan cross-sectional view showing another example of the shape retention bar of the precast concrete formwork according to the fourth example of the present invention.

FIG. 26 is a plan sectional view showing still another example of the shape-retaining bar of the precast concrete formwork according to the fourth example of the present invention.

FIG. 27 is a plan sectional view showing an example of the shape-retaining bar of the precast concrete formwork according to the fifth embodiment of the present invention.

FIG. 28 is a plan cross-sectional view showing another example of the shape retention bar of the precast concrete formwork according to the fifth example of the present invention.

FIG. 29 is a plan sectional view showing still another example of the shape-retaining bar of the precast concrete formwork according to the fifth embodiment of the present invention.

FIG. 30 is a plan sectional view showing an example of the shape-retaining bar of the precast concrete formwork according to the sixth embodiment of the present invention.

FIG. 31 is a plan sectional view showing another example of the shape retention bar of the precast concrete formwork according to the sixth embodiment of the present invention.

FIG. 32 is a plan sectional view showing still another example of the shape-retaining bar of the precast concrete formwork according to the sixth embodiment of the present invention.

[Explanation of Codes] 1,10,15,17,22,28 Precast Concrete Formwork 1A to 1D, 10A to 10D, 15A to 15D, 17A
-17D, 22A-22D, 28A-28D Side surface part 4A, 11A, 11C, 16A-16C, 18B, 18
D, 23A, 23D29A, 29C Slit part 5 Reinforcing bar 6 Reinforcing strip (retaining bar) 7 Concrete K Las (reticulated form)

Claims (1)

[Claims] 1. A precast concrete formwork in which reinforcing bars are embedded in a tubular concrete, wherein a slit part in which the reinforcing bars are exposed is formed on a side surface part, and at least the slit part. A precast concrete formwork, characterized in that shape-reinforcing bars are provided between the concrete on both sides of the mold in addition to the reinforcing bars.