JPH04111866A - Manufacture of hollow precast reinforced concrete column and beam member - Google Patents

Abstract

PURPOSE:To arrange core shearing reinforcing bars so that they are not in the way of the placement of inside forms by dismantling side forms after placed concrete exhibits its specific strength and, at the same time, discharging fluid filled in the hollow inside forms to strip them. CONSTITUTION:A plurality of main beam bars 3 opposed to each other up and down are placed in opposite side forms 2 at a required interval and, at the same time, outside circumferential shearing reinforcing bars 4 consisting of square hoops are placed to the outside circumference of the main beam bars 3 at a required interval. In addition, core shearing reinforcing bars 5 are placed between the main beam bars 3 and 3 opposed to each other in the central part. Then, bag-shaped hollow inside forms 7 capable of expansion and contraction are inserted and filled in spaces 6 partitioned with the outside shearing reinforcing bars 4 and core shearing reinforcing bars 5 in a state of contraction. After that, the insides of them are filled with fluid to expand, and a shape as an inside form is maintained while keeping the hollow inside forms 7 in a state of adherence to each other. In such a state, concrete 8 is placed in the side forms 2, the side forms 2 are dismantled after the concrete 8 exhibits its specific strength to solidify and, at the same time, the fluid in the hollow forms 7 is discharged and the form 7 is released.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method of manufacturing a precast reinforced concrete column/beam member having a hollow portion.

"Prior Art" In general, after supporting the end of a precast reinforced concrete beam member having a hollow part on a precast reinforced concrete column having a hollow part, concrete is poured into the hollow parts of both columns and beams. A construction method that integrates the two is being implemented.

Conventionally, when manufacturing members such as precast reinforced concrete columns and beams with hollow parts used in this type of construction method,
Install the inner formwork within the side formwork at the position that will become the hollow part,
After pouring concrete, the outward and outward formwork was dismantled to form a hollow section, or metal lath or other cast-in formwork that did not require disassembly was used.

"Problems to be Solved by the Invention" However, when placing core shear reinforcing bars inside in addition to shear reinforcing bars on the outer periphery as reinforcement for columns and beams,
This becomes an obstacle to the installation of the inner formwork, making it very difficult to install the formwork, and even if the inner formwork is installed by providing through holes for the core shear reinforcement, the core shear reinforcement There were quality issues such as concrete leaking from the joint with the inner formwork.

In order to solve the above-mentioned conventional problems, the present invention provides shear reinforcing bars and core shear reinforcing bars on the outside and inside of the main reinforcing bars arranged in the side formwork. After installing a bag-shaped hollow inner formwork that can be freely expanded and contracted by filling it with fluid in the space partitioned by the outer shear reinforcing bars and the core shear reinforcing bars, the inside of the side formwork is A precast reinforced concrete column and beam in which concrete is poured into the concrete, and after the concrete has developed a predetermined strength, the side formwork is dismantled, and the fluid in the hollow inner formwork is discharged to remove the hollow inner formwork. This paper proposes a manufacturing method for

"Operation" Even when shear reinforcing bars and core shear reinforcing bars are placed in the side formwork together with the main reinforcement, the hollow inner formwork is in the form of a bag that can be expanded and contracted, so the outer periphery can be sheared in the contracted state. It can be easily inserted into a narrow space partitioned by reinforcing bars and core shear reinforcing bars, and this hollow inner formwork can be easily inserted by filling the inside with a fluid such as air or water after volatilization. It expands and is maintained in the required shape as a formwork, making it possible to mold a hollow part with exposed core shear reinforcing bars without causing concrete leakage.

After the cast concrete has been molded and hardened, the hollow inner formwork can be easily demolded by discharging the fluid inside the formwork and shrinking it.

"Embodiments" Below, embodiments of the present invention shown in the drawings will be described.
Figure 1 shows the state in which a precast reinforced concrete beam with a U-shaped cross section and a hollow part' with an open upper part is formed. At the same time, a plurality of vertically opposing main beam reinforcements 3 are arranged, and peripheral shear reinforcing bars 4 made of square hoops are arranged at required intervals around the outer periphery of the upper and lower main beam reinforcements 3, and each of the upper and lower main beam reinforcements 3 is
Core shear reinforcing bars 5 are arranged between opposing beam main bars 3, 3 in the center of the row.

Next, in the space 6 partitioned by the outer circumferential shear reinforcement 4, the core shear reinforcement 5, and the core shear reinforcement 5, 5,
After inserting a bag-shaped hollow inner formwork 7 in a contracted state that can be expanded and contracted to a predetermined size by filling it with a fluid such as air or water, the inside is filled with fluid and expanded. The shape of the inner formwork is maintained while the hollow inner formworks 7 are brought into close contact with each other.

In this state, concrete 8 is poured into the side formwork 2, and after it has hardened and developed a predetermined strength, the side formwork 1 is dismantled and the fluid in the hollow formwork 7 is discharged to form the hollow mold. Remove the frame 7 from the mold.

Next, Fig. 2 shows the state in which a precast reinforced concrete column having a hollow part in the center is formed. ', and at the same time, outer peripheral shear reinforcing bars 4' made of square hoops are arranged at required intervals around the outer periphery of the main reinforcement 3'.
Furthermore, core shear reinforcing bars 5' are arranged between the opposing column main reinforcements 3' and 3' in the center of each of the three rows of column main reinforcements facing each other.

As in the case of the above-mentioned beam, a space 6' partitioned by the outer circumferential shear reinforcing bars 4', the core shear reinforcing bars 5', and the core shear reinforcing bars 5' and 5' is filled with a bag-like shape that can be expanded and contracted. After inserting the hollow inner formwork 7 in a contracted state, the inside is filled with fluid to expand it, and the hollow inner formworks 7 are kept in close contact with each other to maintain the shape as an inner formwork, and the side formwork 2 is formed. ′
After concrete 8 is poured inside and hardened, it is removed from the mold in the same manner as for the beam.

"Effects of the Invention" As described above, according to the present invention, even when shear reinforcing bars and core shear reinforcing bars are arranged in the side formwork together with the main reinforcement, the hollow inner formwork remains in the form of a bag that can be expanded and contracted. Therefore, it can be easily inserted into a narrow space partitioned by the outer shear reinforcing bars and the core shear reinforcing bars in the contracted state.
After insertion, this hollow inner formwork can be easily expanded by filling the inside with a fluid such as air or water, and the formwork can be maintained in the desired shape without causing concrete leakage. It becomes possible to mold the hollow part where is exposed.

Further, after the cast concrete has been molded and hardened, the hollow inner formwork can be easily demolded by discharging the fluid inside it and causing it to shrink.

In addition to manufacturing precast reinforced concrete columns and beams, this method can also be applied to manufacturing reinforced concrete structures having hollow parts that are cast on site.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional front view showing the molded state of a hollow beam according to the present invention, and FIG. 2 is a vertical sectional plan view showing the molded state of the hollow column.
FIG. 3 is a longitudinal sectional front view showing a hollow beam formed by a conventional method. 1...Bottom formwork, 2...Beam side formwork, 2'...Column side formwork, 3...Beam main reinforcement, 3'...Column main reinforcement, 4...Beam outer circumference shear reinforcement, 4'.
・Column outer circumference shear reinforcing bar, 5... Beam core shear reinforcing bar core, 5
′ ・・Column core shear reinforcement, 6.6′ ・・Space part,
7. Hollow inner formwork, 8. Concrete.

Claims (1)

[Claims] 1) Shear reinforcing bars and core shear reinforcing bars are arranged outside and inside the main reinforcing bars arranged in the side formwork, and a space partitioned by the outer shear reinforcing bars and the core shear reinforcing bars. After installing a bag-shaped hollow inner formwork that can be expanded and contracted by filling and discharging fluid, concrete is poured into the side formwork, and after the concrete has developed a predetermined strength,
A method for manufacturing a precast reinforced concrete column and beam, comprising dismantling the side formwork, discharging the fluid in the hollow inner formwork, and removing the hollow inner formwork.