KR20230134910A - Precast concrete inner mould, precast concrete beam using the same and manufacturing, construction method thereof - Google Patents

Abstract

A precast inner form that uses a precast inner form to form a hollow part inside as a precast concrete beam to reduce self-weight, and also secures efficient bending rigidity by additionally installing beam reinforcement in the precast inner form, A precast concrete beam using this, and its manufacturing and construction method are disclosed.

Description

Precast inner formwork, precast concrete beam using the same, and manufacturing and construction method thereof {PRECAST CONCRETE INNER MOULD, PRECAST CONCRETE BEAM USING THE SAME AND MANUFACTURING, CONSTRUCTION METHOD THEREOF}

The present invention relates to a precast concrete beam manufactured using a precast inner formwork and beam reinforcement. More specifically, a precast inner formwork is used to form a hollow interior as a precast concrete beam to reduce self-weight, and additionally integrate beam reinforcement into the precast inner formwork to secure efficient bending rigidity. It relates to cast inner formwork, precast concrete beams using it, and their manufacturing and construction methods.

Figure 1a shows an example construction of a conventional precast concrete beam.

That is, the precast concrete beam 10 has a rectangular parallelepiped body portion 11 extending continuously in the longitudinal direction,

It can be seen that the connecting reinforcing bars 12 extending upward from the upper surface of the body portion 11 of the rectangular parallelepiped shape are formed as one piece.

Accordingly, decks 13 for floor plates are installed on the upper surfaces of both sides of the body 11 to be supported,

Slab concrete (14) is poured at a constant thickness between both sides of the body portion (11) and on top of the floor deck (13), and the connecting reinforcing bar (12) of the precast concrete beam (10) is connected to the slab reinforcing bar (15). You can see that it is being constructed to be tied together.

At this time, the precast concrete beam (10) is provided with more slab reinforcement (15) at the branch parts considering that a larger bending moment occurs at the branch parts than at the central part, and the branch parts are the areas where the column structure is located. It can be.

At this time, the precast concrete beam 10 is usually manufactured as a PC beam in which prestrain is introduced in advance as a tension member in the reinforced concrete beam. However, even with an extension length of about 10 m, there is a limit to its self-weight being considerably large, so it is divided into two. It is manufactured, assembled and installed.

Accordingly, it can be seen that it is very important in the construction of precast concrete beams to reduce the self-weight of the precast concrete beam 10 and secure bending rigidity more effectively.

Figure 1b is a construction example of a conventional hollow precast concrete beam.

The hollow precast concrete beam has a hollow part (S) formed inside it to reduce its own weight by the amount of concrete excluded by the hollow part.

Accordingly, when using an internal form to form the hollow part (S), manufacturing processes for installation and disassembly are added, so it can be seen that an embedded internal form is used rather than an internal form.

That is, a first step of installing a plurality of main bars 21 and a plurality of shear connecting reinforcing bars 22 whose both ends are bound to the main bars; A second step of installing a plurality of lightweight sections 24 equipped with a plurality of stud bolts 23 at the intersection of the shear connecting reinforcing bars 22, excluding the central part; A third step of installing a built-in internal form (25) to contact the outside of the plurality of shear connecting reinforcing bars (22) and the plurality of lightweight sections (24); A fourth step of installing a plurality of additional main bars (21) and major bars (26); An external form (OF) is installed at a predetermined interval on the outside of the large beam (26), and PC concrete (27) is poured between the external form (OF) and the embedded internal form (25) to form a hollow part (S ) and consists of the fifth step of forming,

The embedded internal form (25) is a rib-lath in the form of a reinforcing bar network with a through hole formed, and is not otherwise demolded. It is installed embedded in the filled concrete (28), and is used as an internal form when pouring PC concrete (27). Therefore, it can be seen that there is an advantage that there is no need for an internal form.

However, since the rib-lath embedded internal form (25, a type of reinforcing bar network) is installed to be supported by the shear connecting reinforcing bar (22), it is formed by the pouring pressure of the PC concrete (27) and the filled concrete (28). Because deformation may occur, there was a limitation that quality control was not easy.

Figure 1c shows an example of a conventional precast steel composite girder 30.

That is, a concrete member 31 extending with a hollow portion S in a first longitudinal direction and having a plurality of holes in a second width direction; A plurality of tension members disposed in a set direction in the concrete member to provide tension to the concrete member; A plurality of section steel members 32 having an exposed surface on the upper surface of the concrete member and integrally coupled with the concrete member; And a precast steel including a plurality of shear connection members 34 that are coupled to the exposed surfaces of each of the section steel members and extend upward, and are embedded in the floor plate member 33 that is integrally coupled to the upper side of the concrete member in the field. A composite girder is disclosed.

Accordingly, since the neutral axis is moved to the compression section by the plurality of section steel members 32, the eccentricity of the tension member increases, allowing a large compressive stress to be introduced to the tension section even if the number of tension members is relatively small.

From this, it can be seen that the conventional precast concrete beam can form a hollow part (S) inside to reduce its own weight, but when using an internal form to form this hollow part (S), the efficiency of manufacturing is reduced by demolding. It is lowered, and there are cases where a built-in internal form (25) is used, but it can be seen that there is a limitation in that quality control is not easy.

In addition, it can be seen that a precast steel composite beam can be manufactured by installing additional section steel members to the PSC beam in order to increase the eccentricity effect, but even in this case, there is a limitation in that a separate internal form must be used.

Republic of Korea Patent Publication No. 10-2010-0069847 (Title of invention: Precast steel composite girder and manufacturing method, Publication date: June 25, 2010) Republic of Korea Patent No. 10-1570484 (Title of invention: HPC column using lightweight embedded internal form, manufacturing method thereof, and construction method using the same, Publication date: November 20, 2015)

Accordingly, the present invention reduces the self-weight by forming a hollow part (S) inside the precast concrete beam, but the hollow part can be formed without separately installing and dismantling the internal form, and the eccentricity effect can be increased. Therefore, the technical problem to be solved is to provide a precast inner form capable of cross-sectional optimization according to the increase in bending rigidity, a precast concrete beam using the same, and a method of manufacturing the same.

The precast inner form of the present invention for achieving the above problem is formed in a U-shaped shape, and the two precast inner forms are set so that the connecting flanges are in contact with each other to form a hollow portion (S) on the inside; and rib reinforcements formed integrally with each other on the inner surfaces of the two precast inner forms, spaced apart from each other. A precast inner form is provided,

The precast concrete beam using the precast inner formwork of the present invention is made of a concrete member in which a body portion (A1) and a connecting flange inside the body portion (A1) are in contact with each other so that a hollow portion (S) is formed. A cast inner mold; including, wherein both precast inner molds are formed in a U-shaped shape and are set so that connecting flanges contact each other to form a hollow portion (S) on the inside; and rib reinforcements formed integrally with each other on the inner surfaces of the two precast inner forms, spaced apart from each other, by PC concrete (C1) that is poured so that the exposed beam reinforcements are buried between the outer form and both precast inner forms. A hollow part (S) is formed by the two precast inner molds in the body part (A1) reinforced by the beam reinforcement.

According to the present invention, the precast inner form is made of precast concrete, and since it is a buried method, it does not need to be separately dismantled, making it convenient to manufacture. Therefore, it is possible to manufacture precast concrete beams more quickly and economically without complicated form equipment. .

In addition, according to the present invention, since a hollow part (S) is formed in the precast inner formwork, the self-weight is reduced accordingly, and the precast inner formwork can also be reduced in self-weight by using rib reinforcement, so it is attached to the hollow part (S). It is possible to maximize the self-weight reduction effect.

In addition, according to the present invention, the beam reinforcement is installed directly on the precast inner form, but the beam reinforcement is located on the top, side, and bottom, so that the position of the beam reinforcement can be naturally set while installing the precast inner form, and the beam reinforcement can be set naturally. By increasing the eccentric effect caused by the reinforcement, it becomes more effective in securing bending rigidity.

Figure 1a is a construction example of a conventional precast concrete beam,
Figure 1b is a construction example of a conventional hollow precast concrete beam,
Figure 1c is an example of a conventional precast steel composite girder,
Figures 2a and 2b are illustrations of the precast inner formwork of the present invention and a precast concrete beam (A) using the same;
Figure 2c is an illustration of the installation of the beam reinforcement of the present invention;
Figures 2d and 2e are illustrations of the construction cross-section of the precast concrete beam (A) of the present invention;
Figures 3a and 3b show the manufacturing and construction flowchart of a precast concrete beam using the precast inner formwork of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

[Precast inner form (100) of the present invention]

Figures 2a and 2b show examples of the precast inner formwork 100 of the present invention and a precast concrete beam (A) using the same.

Referring to FIGS. 2C and 2D, the precast concrete beam (A) is arranged horizontally on a pillar structure to be constructed as a structure, and is installed so that the floor deck 300 is supported on the upper surfaces of both sides, and the central portion and the floor Floor slab concrete (C2) is poured onto the upper part of the deck for construction so that the precast concrete beam (A) and the floor slab deck 300 are integrated with each other.

Accordingly, the precast inner form 100 is formed as a hollow part (S) to reduce the self-weight of the precast concrete beam (A), as shown in Figure 2b, and is buried as is without installing or dismantling a separate inner form. It can be said to be a type of permanent form that allows for the quick and economical production of precast concrete beams (A).

For this purpose, referring to FIG. 2a, the precast inner formwork 100 is formed so that the two connection flanges 120 of the U-shaped precast inner formwork 110 are in contact with each other to form a hollow portion (S), and the concrete Since it is a material, it can be seen that it is formed to facilitate integration with PC concrete (C1, see Figure 3a).

That is, both connection flanges 120 of both precast inner forms 110 are in contact with each other to form a hollow part (S), and since it is made of concrete, it is integrated with PC concrete (C1, see Figure 3a), so that both precast It is composed of a cast inner formwork 110, rib reinforcement 130, and flange connection part 140, and the beam reinforcement 200 is integrally formed on the top, bottom, and sides.

First, it can be seen that both precast inner molds 110 are connected in the form of a square tube with the connecting flanges 120 in contact with each other, as shown in FIGS. 2A and 2B.

At this time, rib reinforcements 130 are formed on the inner surfaces of both precast inner forms 110 to be spaced apart from each other to minimize the thickness of both precast inner forms 110 and provide rigidity to effectively resist concrete pouring pressure. It can be seen that it is possible to provide.

Next, the rib reinforcement 130 is formed integrally with the inner surface of both precast inner forms 110, as shown in Figures 2a and 2b, and serves to reinforce both precast inner forms 110, and are spaced apart from each other. You can see that it is installed.

Accordingly, both precast inner formwork 110 and rib reinforcement 130 are manufactured as one piece, and both precast inner formwork 110 is manufactured from a concrete member, which is advantageous in ensuring integrity because it is the same material as PC concrete (C1). do.

Next, the flange connection portion 140 is used to connect the adjacent connection flanges 120 of the two adjacent precast inner molds 110 to each other, as shown in FIG. 2A.

For example, connection notches 141 are formed at the ends of both connection flanges of both precast inner molds 110, as shown in Figure 2a, and in both connection notches 141 of both precast inner molds 110 adjacent to each other. By inserting the notch strip 142, they are connected to each other and also serve to prevent the PC concrete (C1) from leaking into the hollow portion (S) between the end surfaces of both connecting flanges.

Next, the beam reinforcement 200 is a steel material formed integrally with the top, side, and bottom surfaces of both precast inner molds 110, respectively, as shown in FIG. 2C.

Referring to Figure 2c, studs 220 are formed on the upper and lower surfaces of the horizontal steel plate 210 to ensure unity with both precast inner formwork 110 and PC concrete (C1).

As shown in Figure 2c, the steel beam reinforcement 200 is positioned based on the neutral axis of the precast concrete beam A, which has the effect of increasing the eccentric distance.

Accordingly, depending on whether the bending moment acting on the precast concrete beam (A) is a positive moment or a negative moment,

In the section where positive moment acts, beam reinforcement (200) is formed on the upper surface of both precast inner forms (110),

In the section where the negative moment acts, beam reinforcement (200) is formed on the bottom of both precast inner forms (110),

Beam reinforcements 200 are formed on both sides of the precast inner formwork 110 to resist shear force.

Accordingly, the upper, side, and bottom surfaces of both precast inner molds 110 are formed integrally, so there is no need to install them separately.

[Precast concrete beam (A) using the precast inner formwork (100) of the present invention]

Figures 2d and 2e show an example construction cross-section of the precast concrete beam (A) of the present invention.

First, the precast concrete beam (A) using the precast inner formwork 100 will be simply referred to as precast concrete beam (A).

The precast concrete beam (A) is manufactured from a beam member with a hollow portion formed using the precast inner formwork 100 and beam reinforcement 200 discussed above.

Referring to FIG. 2C, it can be seen that the beam reinforcement 200 is formed by being integrated so that it is exposed to the top, side, or bottom in advance when manufacturing the precast inner formwork 100.

As a result, referring to FIGS. 2d and 2e, the precast concrete beam (A) is formed by integrating the beam reinforcement 200 into the precast inner formwork 100 to form a hollow portion (S), and forming the outer formwork 400. By pouring PC concrete (C1), the precast inner formwork (100) and the beam reinforcement (200) are integrated with each other to form a hollow part (S), which serves to support the end of the floor deck (300). You can see that it is being done.

Looking specifically at this, the precast concrete beam (A) includes a body portion (A1), both upper flanges (A2), reinforcing bars (A3), tension members (A4), stirrup reinforcing bars (A5), as shown in FIGS. 2d and 2e. It can be seen that it was formed to include reinforcing bars (A6) for the floor plate.

First, it can be seen that it is manufactured in the form of a rectangular parallelepiped with both upper flanges (A2) protruding outward on the upper part of the body portion (A1), and a precast inner formwork 100 and beam reinforcement 200 are installed inside the body portion A1. It can be seen that the hollow portion (S) is formed by integration.

This body (A1) is made of reinforced concrete, and a tension member is placed inside so that it behaves as a PSC beam with pre-stress introduced in advance. The reinforcing bar (A3) including the stirrup reinforcing bar (A5) inside, and the tension member (A4) are of length. It can be seen that it is arranged inside the body portion A1 in this direction. The stirrup reinforcing bar (A5) extends upward to the upper surface of the body portion (A1) and is bound to the floor slab reinforcing bar (A6) when pouring the floor slab concrete (C2).

In addition, it can be seen that the precast concrete beam (A) supports the floor deck 300 on the upper surfaces of both sides of the body portion (A1).

In particular, Figure 2d shows that the body portion (A1) and both upper flanges (A2) are formed with a square cross-section, and Figure 2e shows that the body portion (A1) and both upper flanges (A2) are formed with a trapezoidal cross-section. .

In this way, when the body portion (A1) and both upper flanges (A2) are formed to have a trapezoidal cross-section, the cross-section is further formed above the neutral axis of the precast concrete beam (A), so that bending rigidity can be secured more effectively, allowing long-span spans to be secured more effectively. There is an advantage in that it is possible to produce a precast concrete beam (A).

At this time, as shown in Figures 2d and 2e, the precast inner formwork 100 installed inside the body portion (A1) has a hollow portion (S) with both connection flanges 120 of both precast inner formworks 110 in contact with each other. is formed, and since it is a concrete material, it is integrated with PC concrete (C1), and as we have seen, it is composed of both precast inner formwork 110, rib reinforcement 130, and flange connection part 140,

Next, the beam reinforcement 200 is integrally formed on the top, bottom, and side surfaces of the precast inner formwork 100, as shown in FIGS. 2D and 2E,

Next, referring to FIGS. 2D and 2E, the floor deck deck 300 is a deck member installed to construct a floor plate after installing the precast concrete beam (A).

Accordingly, the deck, also pre-fabricated using the precast method, is lifted and installed between the precast concrete beams (A), and floor plate concrete (C2) is poured on top to be integrated.

Next, referring to FIG. 3A, the external formwork 400 is a formwork for manufacturing a precast concrete beam (A) using both precast inner formworks 110.

That is, the side formwork 420 is set on the support plate 410, the stirrup reinforcement (A5) is placed inside the external formwork 400, and the beam reinforcement 200 is formed integrally with the precast inner formwork 110. After setting, reinforcing bars (A3) and tension members (A4) are additionally set inside the external formwork (400), PC concrete (C1) is poured, and when cured, the external formwork (400) is demolded to create the free form of the present invention. The production of the cast concrete beam (A) can be completed.

[Precast concrete beam (A) manufacturing and construction method using the precast inner formwork (100) of the present invention]

Figures 3a and 3b show a flowchart of manufacturing and construction of a precast concrete beam (A) using the precast inner formwork 100 of the present invention.

As described above, the precast concrete beam (A) manufacturing and construction method involves setting the precast inner formwork (100) and the beam reinforcement (200) inside the outer formwork (400) to pour and cure the PC concrete (C1). Afterwards, the external form is demolded to produce a precast concrete beam (A), installed on a column structure, etc., then the deck for the floor plate (300) is installed, and the floor plate concrete (C2) is poured and integrated. You can.

First, a precast concrete beam (A) is manufactured using the external form 400 as shown in Figure 3a.

At this time, referring to Figure 3a, the external formwork 400 can be seen that the side formwork 420 is set on the upper surface of the support plate 410 so that it is spaced apart from each other, and reinforcing bars (A3) and struts are placed on the upper surface of the support plate 410 inside both side formwork. You can see that the rub rebar (A5) is placed first.

The support plate 410 is in the form of a horizontal plate and is used as a formwork panel by installing a steel plate on the upper surface of a concrete base plate extending longitudinally on the ground.

The side formwork 420 may use a steel formwork in the form of two walls installed to continuously extend in the longitudinal direction corresponding to the shape of the body portion A1.

The reinforcing bars (A3) are arranged in large numbers to extend in the longitudinal direction at the lower part of the body portion (A1), and the U-shaped stirrup reinforcing bars (A5) extending upward while surrounding the reinforcing bars (A3) are also arranged in the longitudinal direction. It can be seen that many of them are spaced apart.

Next, referring to FIG. 3A, the precast inner formwork 100 with the beam reinforcement 200 installed between both side formworks 420 is installed.

The beam reinforcement 200 is installed integrally on the top, side, and bottom of the precast inner formwork 100, and the precast inner formwork 100 is provided by the beam reinforcement 200 between the U-shaped stirrup reinforcement bars (A5). The stud 220 can be fixedly set in such a way that it is fastened.

Accordingly, the studs 220 formed on the horizontal steel plate 210 of the beam reinforcement 200 also serve to integrate the poured PC concrete and the precast inner form 100, and the precast inner form 100 is installed. It can be seen that a hollow portion (S) is naturally formed due to this.

Next, as shown in Figure 3a, reinforcing bars (A3) and tension members (A4) are additionally placed between both side molds 420 and the set precast inner mold 100, and PC concrete (C1) is poured. . Accordingly, the precast inner formwork 100, the reinforcing bar (A3), the tension member (A4), and the U-shaped stirrup reinforcing bar (A5) are embedded and integrated by the PC concrete (C1).

Next, as shown in Figure 3a, the cured precast concrete beam (A) is demolded from the external formwork 400, the stirrup reinforcement (A5) is exposed to extend upward, and the body portion (A1) with both upper flanges is formed. Manufacturing of the formed precast concrete beam (A) is completed.

Next, as shown in Figure 3b, the precast concrete beam (A) is installed on the column structure, the floor deck 300 is installed on the precast concrete beam (A), and then the floor plate (B) is connected to the floor plate concrete (C2). ) is constructed by pouring.

The precast concrete beam (A) is installed to be horizontally connected to the pillar structure for the construction of a large structure, and the deck for the floor plate (300) is supported on the side of the precast concrete beam (A), and then the reinforcement bar (A6) for the floor plate is supported on the side of the precast concrete beam (A). ) is placed on the top of the U-shaped stirrup reinforcement (A5), and the floor plate concrete (C2) is poured and cured.

The precast concrete beam (A) is formed with a hollow portion (S) to reduce its own weight and is advantageous for installing the floor deck 300 by both upper flanges, and has bending rigidity thanks to the beam reinforcement 200. As enough materials are secured, they can be manufactured over long spans, making more rapid and economical precast concrete beam (A) construction possible.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: Precast inner form 110: Both precast inner form
120: Connection flange 130: Rib reinforcement
140: Flange connection 141: Notch for connection
142: Notch strip
200: beam reinforcement 210: horizontal steel plate
220: Stud 300: Deck for floor plate
400: External form 410: Support plate
420: Side formwork A: Precast concrete beam
A1: Body A2: Both upper flanges
A3: Rebar A4: Tension material
A5: Stirrup rebar A6: Rebar for floor plate
C1: PC concrete C2: Floor plate concrete

Claims (10)

Both precast inner molds 110 are formed in a U-shaped shape and are set so that the connecting flanges 120 are in contact with each other and a hollow portion S is formed on the inside; and
A precast inner form comprising; rib reinforcements 130 formed integrally with each other on the inner surfaces of the two precast inner forms 110 and spaced apart from each other. According to paragraph 1,
Both precast inner formwork 110 further includes beam reinforcement 200,
The beam reinforcement 200 forms studs 220 on the upper and lower surfaces of the horizontal steel plate 210 to ensure integrity with both precast inner formwork 110 and PC concrete (C1), A precast inner form that increases the eccentric distance by the beam reinforcement (200) based on the neutral axis of the cast concrete beam (A). According to paragraph 1,
At the ends of both connection flanges 120 of both precast inner forms 110,
Connecting notches 141 are formed, and notch strips 142 are inserted into both connecting notches 141 of both precast inner forms 110 adjacent to each other to connect them, and PC concrete (PC concrete) is inserted between the end surfaces of both connecting flanges. Precast inner formwork that prevents C1) from leaking into the hollow part (S). It includes a body portion (A1) and a double precast inner formwork 110 made of a concrete member in which the connection flange 120 is in contact with each other inside the body portion A1 so that a hollow portion S is formed,
The two precast inner molds 110 are formed in a U-shape and are set so that the connecting flanges 120 are in contact with each other to form a hollow portion S on the inside; And rib reinforcements 130 formed integrally with each other on the inner surfaces of both precast inner molds 110, and spaced apart from each other,
The body part (A1) is reinforced by the beam reinforcement 200 by PC concrete (C1), which is poured so that the exposed beam reinforcement 200 is buried between the external form 400 and both precast inner forms 110. A precast concrete beam using a precast inner formwork such that a hollow portion (S) is formed by the two precast inner formworks (110). According to paragraph 4,
The beam reinforcement 200 is,
In the section where a positive moment acts on the precast concrete beam (A), the beam reinforcement (200) is formed on the upper surface of both precast inner forms (110),
In the section where the negative moment acts, the beam reinforcement 200 is formed on the bottom of both precast inner forms 110,
A precast concrete beam using a precast inner form so that the beam reinforcement (200) is formed on the sides of both precast inner forms (110) to resist shear force. (a) installing the precast inner formwork 100 with the beam reinforcement 200 installed between the two side forms 420 of the outer formwork 400; and
(b) pouring PC concrete (C1) between both side molds 420 and the set precast inner mold 100 and demolding the precast concrete beam (A) cured from the outer mold 400; Includes,
The precast inner formwork 100 includes two precast inner formworks 110 formed in a U-shape so that the connecting flanges 120 are in contact with each other to form a hollow part S on the inside; and rib reinforcements 130 formed integrally with each other on the inner surfaces of both precast inner forms 110, spaced apart from each other. A method of manufacturing a precast concrete beam using a precast inner form including a. According to clause 6,
The two precast inner formworks 110 are,
Further including a beam reinforcement (200) including a horizontal steel plate (210) formed integrally,
The beam reinforcement 200 forms studs 220 on the upper and lower surfaces of the horizontal steel plate 210 to ensure integrity with both precast inner formwork 110 and PC concrete (C1), A method of manufacturing a precast concrete beam using a precast inner formwork in which the steel beam reinforcement (200) is positioned based on the neutral axis of the cast concrete beam (A) to increase the eccentric distance. According to clause 6,
The external formwork 400 is,
Setting the side formwork 420 on the support plate 410, placing stirrup reinforcement (A5) inside the external formwork 400, and setting the precast inner formwork 110 in which the beam reinforcement 200 is integrally formed. Then, rebar (A3) and tension material (A4) are additionally set inside the external formwork (400), PC concrete (C1) is poured, and when cured, the external formwork (400) is demolded to form a precast concrete beam (A). ) Precast concrete beam manufacturing method using precast inner formwork to complete manufacturing. (a) installing the precast inner formwork 100 with the beam reinforcement 200 installed between the two side forms 420 of the outer formwork 400;
(b) pouring PC concrete (C1) between both side molds 420 and the set precast inner mold 100 and demolding the precast concrete beam (A) cured from the outer mold 400;
(c) installing the cured precast concrete beam (A) from the external formwork (400); and
(d) installing the floor deck 300 on the precast concrete beam (A) and then constructing the floor plate (B) by pouring floor concrete (C2);
The precast inner formwork 100 includes two precast inner formworks 110 formed in a U-shape so that the connecting flanges 120 are in contact with each other to form a hollow part S on the inside; and rib reinforcements 130 formed integrally with each other on the inner surfaces of both precast inner forms 110, spaced apart from each other. A precast concrete beam construction method using a precast inner form including a. According to clause 9,
The precast concrete beam (A) in step (b) is,
The precast inner formwork 100 and the beam reinforcement 200 are integrated to form a hollow part (S), and it is manufactured in the form of a rectangular parallelepiped with both upper flanges (A2) protruding outward at the top, and stirrup reinforcement ( It includes a body portion (A1) in which a reinforcing bar (A3) including A5) and a tension member (A4) are disposed inside in the longitudinal direction,
The stirrup reinforcing bar (A5) extends upward to the upper surface of the body portion (A1) to be bound to the floor plate reinforcing bar (A6) when pouring the floor plate concrete (C2), and the precast concrete beam (A) is connected to the body portion (A1). A precast concrete beam construction method using a precast inner form so that the floor deck 300 is supported on the upper surfaces of both sides of A1).