Half precast beam and method for manufacturing same

Abstract

To provide a half precast beam which can reduce the labor required for arranging beam reinforcement while reducing the labor required for installing and removing formwork, and which is high in quality and has high overall rigidity and integrity, and a method for manufacturing the same.SOLUTION: A half precast beam 100J is formed which includes a pair of reinforced precast concrete slabs 50Q in which a portion of each of a plurality of reinforcing bars 10L is embedded at intervals in the longitudinal direction of a precast concrete slab 20, and each reinforcing bar 10L has an open portion 10a, in which the pair of reinforced precast concrete slabs 50Q are arranged with the open portions 10a of both reinforcing bars 10L facing the other side, and with a gap G between them, with portions of both reinforcing bars 10L overlapping each other to form annular stirrup bars 10L', and a post-cast concrete body 60 is provided in the gap G.SELECTED DRAWING: Figure 21

Description

[Technical Field]

[0001] The present invention relates to a half precast beam and a method for manufacturing the same. [Background technology]

[0002] When constructing upper floor beams and foundation beams (hereinafter referred to as reinforced concrete beams) of a building made of RC (Reinforced Concrete) on site, a method may be applied in which a pair of PCa (Precast) concrete slabs manufactured in a factory or the like is placed at the beam construction position on site with a gap between them, beam reinforcement is placed in the gap, and concrete is poured into the gap using the precast concrete slabs as formwork (side frames) to construct the reinforced concrete beams, in order to reduce the labor required for installing temporary members and improve construction efficiency.

[0003] Because a portion of the reinforced concrete beam is formed from precast concrete slabs, reinforced concrete beams constructed using this construction method can be called half-precast beams. The use of half-precast beams reduces labor during formwork installation by using the precast concrete slabs as formwork. Since the precast concrete slabs remain as components of the half-precast beam, labor is also reduced during formwork removal. Furthermore, the formwork can be included in the thickness of the reinforcing steel, allowing the precast portion to be expected to have sufficient structural strength. Since the precast concrete slabs are fabricated in a factory, problems such as concrete junk and cracking, which are common when constructing an entire reinforced concrete beam on-site, can be reduced. By ensuring the accuracy of reinforcement, quality can be improved. Furthermore, so-called full-precast beams, in which the entire reinforced concrete beam is made from precast concrete slabs, suffer from issues such as increased weight, reduced portability, and the need for high-capacity lifting equipment, which can increase construction costs. However, the use of half-precast beams can solve these issues.

[0004] Here, Patent Document 1 proposes a beam construction method. This beam construction method is a method for constructing a foundation beam of reinforced concrete construction, in which the main reinforcement bars at the lower end of the beam are embedded in the longitudinal direction, the stirrup reinforcement bars are embedded in the lateral direction, and precast plates are first fabricated with one end of the stirrup reinforcement exposed from the side to form a stirrup anchorage section and the other end exposed from the top surface, the pair of precast plates are vertically installed on a concrete slab to face each other with the exposed sides of the stirrup anchorage section facing each other, center beam reinforcement is arranged to satisfy the required amounts of main reinforcement and shear reinforcement in the space formed by the pair of precast plates installed opposite each other, and concrete is poured into the space to anchor the center beam reinforcement and stirrup anchorage section in the concrete, thereby constructing the foundation beam.

[0005] Meanwhile, Patent Document 2 proposes a precast concrete foundation beam structure. This precast concrete foundation beam structure is a foundation beam structure consisting of a foundation beam and a pile head foundation, and is formed by placing a pair of precast concrete beam members, each having main beam reinforcement bars protruding in the longitudinal direction of the foundation beam and first stirrups protruding in the beam width direction of the foundation beam so as to surround the main beam reinforcement bars, on a base plate facing each other to form a first joint space in the beam width direction, and arranging second stirrups in a second joint space between the pair of precast concrete beam members and the pile head foundation so as to surround the pair of main beam reinforcement bars, and pouring concrete into the first and second joint spaces. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-79695 [Patent Document 2] Japanese Patent Publication No. 2023-19966 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the beam construction method described in Patent Document 1, when constructing reinforced concrete beams, the work related to beam formwork at the construction site can be significantly reduced, thereby realizing labor savings in on-site work.

[0008] Incidentally, while the application of half precast beams can greatly improve the labor savings when installing and removing formwork as described above, the beam construction method described in Patent Document 1 still requires the labor of arranging the beam reinforcement within the formwork, and when half precast beams are used, precast concrete slabs that function as formwork can be installed on the left and right sides of the beam reinforcement work space prior to the reinforcement work, which can reduce the workability and safety of the reinforcement work.Although labor savings can be achieved when installing and removing formwork, there is room for improvement in the workability of the entire work, including the reinforcement work.

[0009] Furthermore, in the precast concrete foundation beam structure described in Patent Document 2, the first stirrup bars of both of a pair of precast concrete beam members are arranged next to each other at positions separated from each other in the first joint space, and concrete is simply poured into the first joint space, which raises concerns about the low rigidity, integrity, and torsional strength of the foundation beam that is formed, and also raises concerns about the need to ensure space between the inner reinforcing bars and the large beam width due to the lack of reinforcing bars that are connected in a series in the beam width direction.

[0010] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a half precast beam and a method for manufacturing the same, which has high quality, high overall rigidity and integrity, and which can reduce the labor required for installing and removing formwork by using precast concrete slabs that make up the half precast beam, while also reducing the labor required for beam reinforcement arrangement. [Means for solving the problem]

[0011] In order to achieve the above object, one aspect of the half precast beam according to the present invention is as follows: a pair of reinforced precast concrete slabs, each of which has a plurality of reinforcing bars embedded at intervals in the longitudinal direction of the precast concrete slabs, and each of which has an opening; The pair of reinforced precast concrete slabs are arranged with the open parts of both reinforcing bars facing the other side, with a gap between them and parts of both reinforcing bars overlapping to form annular stirrup bars, and a post-cast concrete body is provided in the gap.

[0012] According to this aspect, a pair of reinforced precast concrete slabs are arranged with a gap between them, with the open parts of both reinforcing bars facing the other side and parts of both bars overlapping each other to form a ring-shaped stirrup bar, and a post-cast concrete body is placed in the gap, thereby forming a high-quality half-precast beam with high overall rigidity and integrity, which reduces the labor required for arranging the beam bars.

[0013] Here, the "annular" in annular stirrup bars includes rectangular frame shapes and circular ring shapes. The reinforcing bars may have hooks at the ends or may have no hooks and have a sufficient anchorage length.

[0014] In another aspect of the half precast beam according to the present invention, The plurality of reinforcing bars of each of the pair of reinforced precast concrete slabs are characterized in that main bars extending in the longitudinal direction are attached to the plurality of reinforcing bars of each of the pair of reinforced precast concrete slabs.

[0015] According to this aspect, since main reinforcement bars extending in the longitudinal direction are attached to the multiple reinforcing bars of both of a pair of reinforced concrete slabs, the beam reinforcement is automatically arranged when the pair of reinforced concrete slabs are installed.Therefore, the precast concrete slabs can eliminate or reduce the labor required for installing and removing formwork, while also eliminating the need for beam reinforcement arrangement work.

[0016] Another aspect of the half precast beam according to the present invention is as follows: The reinforcing bars are characterized in that the overlapping portions of some of the reinforcing bars are not connected.

[0017] According to this embodiment, the overlapping portions of the reinforcing bars are not connected, which further improves the manufacturing efficiency of half precast beams.

[0018] Another aspect of the half precast beam according to the present invention is as follows: The reinforcing bars are characterized in that the overlapping portions of the reinforcing bars are connected to each other.

[0019] According to this embodiment, by connecting the overlapping portions of the reinforcing bars, it is possible to form a half-precast beam in which the reinforcing bars are more firmly integrated together while eliminating or reducing the labor required for arranging the beam bars.

[0020] Another aspect of the half precast beam according to the present invention is as follows: The pair of reinforcing steel precast concrete slabs have the same shape and configuration.

[0021] According to this aspect, since a pair of reinforcing steel precast concrete slabs have the same shape and configuration, mass productivity of reinforcing steel precast concrete slabs can be improved.

[0022] Another aspect of the half precast beam according to the present invention is as follows: A pair of reinforced concrete slabs is provided, in which the vertical reinforcement bars, upper horizontal reinforcement bars bent at the upper ends of the vertical reinforcement bars and extending horizontally, upper hooks bent at the ends of the upper horizontal reinforcement bars and extending downward, lower horizontal reinforcement bars bent at the lower ends of the vertical reinforcement bars and extending horizontally, and lower hooks bent at the ends of the lower horizontal reinforcement bars and extending upward, are embedded in the longitudinal direction of the precast concrete slab at intervals, and upper end main reinforcement bars extending in the longitudinal direction are attached below the plurality of upper horizontal reinforcement bars, and lower end main reinforcement bars extending in the longitudinal direction are attached above the plurality of lower horizontal reinforcement bars, The pair of reinforced precast concrete slabs are arranged with a gap between them, with both upper horizontal bars overlapping each other and both lower horizontal bars overlapping each other, and a post-cast concrete body is provided in the gap.

[0023] According to this embodiment, a pair of reinforced precast concrete slabs, in which the vertical reinforcement bars that make up a plurality of C-shaped reinforcing bars are embedded, are arranged with a gap between them, with the upper horizontal reinforcement bars that make up both reinforcing bars overlapping each other and the lower horizontal reinforcement bars that make up both reinforcing bars overlapping each other, and upper main reinforcement bars are pre-attached below the plurality of upper horizontal reinforcement bars and lower main reinforcement bars are pre-attached above the plurality of lower horizontal reinforcement bars, and a post-cast concrete body is provided in the gap, so that the beam reinforcement is automatically arranged when the pair of reinforced precast concrete slabs are installed, and since the precast concrete slabs reduce the labor required for installing and removing formwork, the work of arranging the beam reinforcement can be eliminated or reduced, and because the work is manufactured in a factory, quality can be ensured.

[0024] Furthermore, by overlapping the reinforcing bars of a pair of steel-reinforced precast concrete slabs, a half-precast beam can be formed that has high torsional strength and can also ensure toughness by providing a sufficient restraint area.

[0025] The half precast beam of this embodiment can be applied to the beams of the upper floors and foundation beams that make up a building. When the beam width is small, it is extremely difficult for workers to enter a pair of precast concrete slabs to perform reinforcement work. Furthermore, even for foundation beams with a high beam depth of about 2 to 3 meters, it is difficult to enter a pair of precast concrete slabs to perform beam reinforcement work. Therefore, eliminating or reducing the labor required for entering a pair of precast concrete slabs to perform reinforcement work is desirable, as it significantly improves the workability of foundation beams.

[0026] Another aspect of the half precast beam according to the present invention is as follows: Among the upper end main reinforcements attached to the upper cross bars of each of the pair of reinforced concrete slabs, the upper end main reinforcements arranged at the lap positions of both upper cross bars are attached only below one of the upper cross bars, and are not attached below the other upper cross bar, Among the lower end main reinforcements attached to the lower transverse reinforcements of each of the pair of reinforced concrete slabs, the lower end main reinforcements arranged at the lap positions of both the lower transverse reinforcements are attached only above one of the lower transverse reinforcements, and are not attached above the other lower transverse reinforcement, When the upper horizontal reinforcements are overlapped with each other and the lower horizontal reinforcements are overlapped with each other, the upper main reinforcements are aligned horizontally at equal or approximately equal intervals, and the lower main reinforcements are aligned horizontally at equal or approximately equal intervals.

[0027] According to this aspect, of the upper main reinforcements (or lower main reinforcements) attached to each upper transverse reinforcement (or lower transverse reinforcement) of a pair of reinforced concrete slabs, the upper main reinforcements (or lower main reinforcements) arranged at the overlap positions of both upper transverse reinforcements (or lower transverse reinforcements) are attached only below (or above) one of the upper transverse reinforcements (or one lower transverse reinforcement), and are not attached below (or above) the other upper transverse reinforcement (or the other lower transverse reinforcement). When the upper transverse reinforcements are overlapped and the lower transverse reinforcements are overlapped, the multiple upper main reinforcements are aligned horizontally at equal or approximately equal intervals, and the multiple lower main reinforcements are aligned horizontally at equal or approximately equal intervals. This prevents interference between the multiple upper main reinforcements at the overlap positions of the upper transverse reinforcements and the multiple lower main reinforcements at the overlap positions of the lower transverse reinforcements, and allows the upper and lower main reinforcements to be aligned horizontally at equal or approximately equal intervals. Here, "approximately equal intervals" does not mean strictly equal intervals, but includes cases where the intervals vary from part to part of the beam from a design perspective, or cases where the intervals vary from place to place due to manufacturing errors (reinforcement errors).

[0028] Another aspect of the half precast beam according to the present invention is as follows: the upper end main reinforcement is disposed between the corresponding upper hooks of the pair of reinforcing bar-equipped precast concrete slabs, and both upper hooks are engaged with the upper end main reinforcement; The lower end main reinforcement is disposed between the corresponding lower hooks of the pair of reinforcing steel precast concrete slabs, and both lower hooks are engaged with the lower end main reinforcement.

[0029] According to this aspect, for example, one upper main reinforcement is arranged between the corresponding upper hooks of a pair of reinforced precast concrete slabs, engaging both upper hooks, and for example, one lower main reinforcement is arranged between the corresponding lower hooks, engaging both lower hooks, thereby effectively preventing each reinforcing bar from spreading out laterally.

[0030] Another aspect of the half precast beam according to the present invention is as follows: The precast concrete slab is characterized in that some of the upper main reinforcements among the plurality of upper main reinforcements are embedded, and some of the lower main reinforcements among the plurality of lower main reinforcements are embedded.

[0031] According to this embodiment, some of the upper main reinforcements (for example, one upper main reinforcement) of the multiple upper main reinforcements and some of the lower main reinforcements (for example, one lower main reinforcement) of the multiple lower main reinforcements are embedded in the precast concrete slab, so that in addition to the vertical reinforcements that make up the reinforcing bars, the upper and lower main reinforcements are embedded in the precast concrete slab, which makes it possible to suppress cracks during transportation and installation of the precast concrete slab that makes up the reinforced precast concrete slab before producing the half precast beam.

[0032] Another aspect of the half precast beam according to the present invention is as follows: The precast concrete slab comprises a vertical slab extending in the vertical direction, and an upper horizontal slab and a lower horizontal slab extending horizontally from the upper end and lower end of the vertical slab, respectively, and is characterized in that some of the upper main reinforcements among the plurality of upper main reinforcements are embedded in the upper horizontal slab, and some of the lower main reinforcements among the plurality of lower main reinforcements are embedded in the lower horizontal slab.

[0033] According to this aspect, in a configuration in which the precast concrete slab comprises a vertical slab and upper and lower horizontal slabs extending horizontally from the upper and lower ends of the vertical slab, some of the upper main reinforcing bars (for example, one upper main reinforcing bar) of the multiple upper main reinforcing bars are embedded in the upper horizontal slab, and some of the lower main reinforcing bars (for example, one lower main reinforcing bar) of the multiple lower main reinforcing bars are embedded in the lower horizontal slab.This means that in addition to the vertical reinforcing bars that make up the reinforcing bars, the upper and lower main reinforcing bars are embedded in the precast concrete slab comprising the upper and lower horizontal slabs, and cracks can be suppressed during transportation and installation of the precast concrete slab that constitutes the reinforced precast concrete slab before the half precast beam is manufactured.

[0034] Another aspect of the half precast beam according to the present invention is as follows: The precast concrete slab comprises a vertical slab extending in the vertical direction and a lower horizontal slab extending in the horizontal direction from a lower end of the vertical slab, and a plurality of the lower end main reinforcements are embedded in the lower horizontal slab, The end faces of the lower horizontal plates of the pair of reinforced precast concrete slabs abut against each other, and some or all of the lower main bars of the plurality of lower main bars are embedded in both lower horizontal plates.

[0035] According to this aspect, the precast concrete slab comprises a vertical slab and a lower horizontal slab extending horizontally from the lower end of the vertical slab, and in a configuration in which the end faces of both lower horizontal slabs of a pair of reinforced concrete slabs are in contact with each other, forming a gap above them, some or all of the multiple lower main reinforcements are embedded in both lower horizontal slabs of the pair of reinforced concrete slabs, so that in addition to the vertical reinforcement that constitutes the reinforcing bars, the lower main reinforcements are embedded in the precast concrete slab comprising the lower horizontal slab, and cracks can be suppressed during transportation and installation of the precast concrete slab that constitutes the reinforced precast concrete slab before the half precast beam is made.

[0036] Another aspect of the half precast beam according to the present invention is as follows: The precast concrete slab comprises a vertical slab extending in a vertical direction; An upper recess and a lower recess are provided on the inside of the upper end and the lower end of the vertical plate, respectively; The upper end main reinforcement adjacent to the upper depression is separated laterally, and the lower end main reinforcement adjacent to the lower depression is separated laterally.

[0037] According to this aspect, the vertical slab of the precast concrete slab has an upper recess and a lower recess on the inside of its upper end and lower end, respectively, and the upper end main reinforcement and lower end main reinforcement adjacent to each of the upper and lower recesses are separated laterally, so that when forming the post-cast concrete body, the concrete can be sufficiently wrapped around the upper end main reinforcement and lower end main reinforcement adjacent to the vertical slab, and the upper end main reinforcement and lower end main reinforcement arranged at the end can be embedded without gaps inside the post-cast concrete body.

[0038] Another aspect of the half precast beam according to the present invention is as follows: The reinforcing bars comprise a plurality of reinforcing bars, each of which has a vertical reinforcing bar, an upper horizontal reinforcing bar that is bent at the top end of the vertical reinforcing bar and extends horizontally, an upper hook that is bent at the end of the upper horizontal reinforcing bar and extends downward, a lower horizontal reinforcing bar that is bent at the bottom end of the vertical reinforcing bar and extends horizontally, and a lower hook that is bent at the end of the lower horizontal reinforcing bar and extends upward, all of which are connected to form a C-shape. The structure is provided with a plurality of separate reinforcing bars, each of which includes a separate vertical bar, a separate upper horizontal bar that is bent at the upper end of the separate vertical bar and extends horizontally, and a separate lower horizontal bar that is bent at the lower end of the separate vertical bar and extends horizontally, and these bars are connected to form a U-shape. The separate longitudinal reinforcement of each of the plurality of separate reinforcing bars is embedded at intervals in the longitudinal direction of the precast concrete slab, The upper and lower cross bars of the corresponding reinforcing bars are respectively lapped and arranged and tied or welded to the separate upper and lower cross bars of the separate reinforcing bars, a pair of second reinforcing bars in which upper end main reinforcements extending in the longitudinal direction are attached below the plurality of upper horizontal reinforcements and lower end main reinforcements extending in the longitudinal direction are attached above the plurality of lower horizontal reinforcements; The pair of precast concrete slabs with second reinforcing bars are arranged with a gap between them, with both upper horizontal bars overlapping each other and both lower horizontal bars overlapping each other, and a post-cast concrete body is provided in the gap.

[0039] According to this embodiment, the separate vertical reinforcements that form the multiple separate U-shaped reinforcement bars are embedded at intervals in the longitudinal direction of the precast concrete slab, and the upper and lower horizontal reinforcements of the multiple C-shaped reinforcement bars are respectively arranged and wrapped around the separate upper horizontal reinforcement and separate lower horizontal reinforcement that form each separate reinforcement bar, and after being tied together, upper main reinforcements are attached below the multiple upper horizontal reinforcement bars and lower main reinforcements are attached above the multiple lower horizontal reinforcement bars. A post-cast concrete body is provided in the gap between the pair of second reinforced precast concrete slabs, so that the beam reinforcement is automatically arranged when the pair of second reinforced precast concrete slabs are installed. Therefore, the precast concrete slabs reduce the labor required for installing and removing formwork, and the work of arranging the beam reinforcement can be eliminated or reduced, and quality can be ensured because the work is produced in a factory. Furthermore, compared to the separate U-shaped reinforcing bars where separate vertical bars are embedded in the precast concrete slab, the entire C-shaped reinforcing bars that are tied together are embedded in the post-cast concrete, which further enhances the shear reinforcement effect of the reinforcing bars. As a result, even if the precast concrete slab and the post-cast concrete body are not well integrated, the C-shaped reinforcing bars will provide a high shear reinforcement effect.

[0040] Another aspect of the half precast beam according to the present invention is as follows: The present invention is characterized in that, in the longitudinal direction, between the reinforcing bars that are tied or welded to the separate reinforcing bars, there are reinforcing bars that do not have opposing separate reinforcing bars.

[0041] According to this aspect, between the reinforcing bars that are tied to the separate reinforcing bars, there are reinforcing bars that do not have other separate reinforcing bars. In other words, in addition to the reinforcing bars that are connected to the separate reinforcing bars, there are reinforcing bars that are not connected to the separate reinforcing bars. This allows for the arrangement of a number of reinforcing bars that can obtain the desired shear reinforcement effect, regardless of the number of separate reinforcing bars. Here, the reinforcing bars that are not connected to the separate reinforcing bars are connected as a whole to the reinforcing bars that are connected to the separate reinforcing bars via the upper main reinforcing bars and the lower main reinforcing bars.

[0042] Another aspect of the half precast beam according to the present invention is as follows: The present invention is characterized in that wavy reinforcing bars that extend vertically and have a wavy shape are connected to the vertical bars and the separate vertical bars.

[0043] According to this aspect, by connecting the vertically extending wavy reinforcement bars to the vertical reinforcement bars and the separate vertical reinforcement bars, it is possible to achieve stronger integration between the U-shaped separate reinforcement bars and the C-shaped reinforcement bars. Furthermore, this configuration enables the vertical reinforcement bars, the separate vertical reinforcement bars, and the wavy reinforcement bars between them to resist, in a similar manner to a truss beam, pressure acting on the inside of the precast concrete slab when concrete is poured in the construction of a post-cast concrete body, and earth pressure acting on the outside of the precast concrete slab when soil is backfilled before concrete is poured.

[0044] Another aspect of the half precast beam according to the present invention is as follows: A feature of this method is that a core bar is further provided inside the C-shaped reinforcing bar, which is engaged with the upper end main bar and the lower end main bar.

[0045] According to this embodiment, a core bar is further provided inside the C-shaped reinforcing bar, which is engaged with the upper end main bar and the lower end main bar, thereby providing shear reinforcement through the core bar.

[0046] Another aspect of the half precast beam according to the present invention is as follows: The upper end main reinforcement is provided in a plurality of stages, and each stage includes a plurality of the upper end main reinforcement, The lower end main reinforcement is provided in a plurality of stages, and each stage includes a plurality of the lower end main reinforcement.

[0047] According to this embodiment, the upper main reinforcement is provided in multiple stages, each stage containing multiple upper main reinforcement, and the lower main reinforcement is provided in multiple stages, each stage containing multiple lower main reinforcement, thereby making it possible to form a half precast beam with even greater strength.

[0048] Another aspect of the half precast beam according to the present invention is as follows: Auxiliary reinforcement to prevent sagging or shaking of the upper horizontal reinforcement to which the upper end main reinforcement is attached is arranged so as to straddle the upper horizontal reinforcement or the upper hook and the vertical reinforcement, Auxiliary reinforcements for preventing the lower horizontal reinforcement to which the lower end main reinforcement is attached from sagging or swaying are arranged so as to straddle the vertical reinforcement from the lower horizontal reinforcement or the lower hook.

[0049] According to this aspect, auxiliary reinforcement is arranged to prevent the upper horizontal reinforcement to which the upper main reinforcement is attached from sagging or from swaying when hung, and auxiliary reinforcement is arranged to prevent the lower horizontal reinforcement to which the lower main reinforcement is attached from sagging or from swaying, so that the auxiliary reinforcement can effectively prevent the upper horizontal reinforcement and lower horizontal reinforcement from sagging or from swaying when hung, which is caused by the weight of the upper main reinforcement and lower main reinforcement.

[0050] Another aspect of the half precast beam according to the present invention is as follows: Among the multiple reinforcing bars arranged in the longitudinal direction, some of the reinforcing bars have a relatively large cross-sectional diameter, and these large diameter reinforcing bars prevent sagging or swaying of both the upper horizontal bars and the lower horizontal bars.

[0051] According to this aspect, some of the multiple reinforcing bars have a relatively large cross-sectional diameter, and these large diameter reinforcing bars prevent both the upper and lower transverse bars from sagging or swaying when hung.This makes it possible to effectively prevent the upper and lower transverse bars from sagging or swaying when hung, which is caused by the weight of the upper and lower main bars, using only some of the reinforcing bars, without using auxiliary bars.

[0052] Another aspect of the half precast beam according to the present invention is as follows: One of the upper hooks of each of the pair of reinforcing steel precast concrete slabs is a 90-degree hook or a 135-degree hook, and the other is a 135-degree hook; One of the lower hooks of each of the pair of reinforcing steel precast concrete slabs is a 90-degree hook or a 135-degree hook, and the other is a 135-degree hook.

[0053] According to this aspect, the pair of upper hooks and the pair of lower hooks that engage with each other are both a combination of a 135-degree hook and a 90-degree hook, or a combination of a 135-degree hook and a 135-degree hook, thereby improving the stress transferability between the reinforcing bars of a pair of reinforced precast concrete slabs. More specifically, when a tensile force acting on one of the reinforcing bars surrounding the upper or lower end main bars transfers the stress to the reinforcing bar on the opposite side, the upper or lower end main bars between them act as dowels, improving stress transferability compared to when the upper or lower end main bars are not present.

[0054] In addition, one aspect of the method for manufacturing a half precast beam according to the present invention is to A pair of reinforced precast concrete slabs is provided, each of which has a plurality of reinforcing bars embedded at intervals in the longitudinal direction of the precast concrete slab, and each of the reinforcing bars has an opening; One of the reinforcing bars is positioned with the open portion of the reinforcing bar facing the other side, and the other reinforcing bar is moved with the open portion of the reinforcing bar facing the other side, and portions of both reinforcing bars are overlapped to form annular stirrup bars and positioned with a gap between them; The method is characterized in that a half precast beam is produced by pouring concrete into the gap to form a post-cast concrete body.

[0055] According to this aspect, a pair of reinforced precast concrete slabs are arranged with a gap between them, with the open parts of both reinforcing bars facing each other and parts of them overlapping to form a ring-shaped stirrup bar, and concrete is poured into the gap to form a post-cast concrete body, thereby reducing the labor required for arranging the beam bars and producing a high-quality half-precast beam with high overall rigidity and integrity.

[0056] Another aspect of the method for manufacturing a half precast beam according to the present invention is to At the stage when the pair of reinforced precast concrete slabs is prepared, main reinforcements extending in the longitudinal direction are attached to the plurality of reinforcing bars of both slabs.

[0057] According to this aspect, when a pair of reinforced precast concrete slabs are prepared, main reinforcement bars extending longitudinally are attached to the multiple reinforcing bars on both slabs. As a result, when the pair of reinforced precast concrete slabs are installed, the beam reinforcement is automatically arranged, and the precast concrete slabs can eliminate or reduce the labor required for installing and removing formwork, while also eliminating the need for beam reinforcement arrangement work.

[0058] Another aspect of the method for manufacturing a half precast beam according to the present invention is to A pair of reinforced concrete slabs is prepared, in which a plurality of reinforcing bars are embedded in the longitudinal direction of the precast concrete slab at intervals, each of which has a C-shape consisting of vertical bars, upper horizontal bars that bend at the upper ends of the vertical bars and extend horizontally, upper hooks that bend at the ends of the upper horizontal bars and extend downward, lower horizontal bars that bend at the lower ends of the vertical bars and extend horizontally, and lower hooks that bend at the ends of the lower horizontal bars and extend upward, and upper main bars that extend longitudinally are attached below the plurality of upper horizontal bars, and lower main bars that extend longitudinally are attached above the plurality of lower horizontal bars, One of the reinforcing steel precast concrete slabs is positioned, and the other reinforcing steel precast concrete slab is moved laterally to pass its lower cross bars, lower hooks, and lower end main bars between the upper hooks and lower hooks of one of the reinforcing steel precast concrete slabs.The other reinforcing steel precast concrete slab is then lowered and installed using a crane, forklift, etc., so that the upper cross bars of both slabs overlap each other and the lower cross bars of both slabs overlap each other, while the other reinforcing steel precast concrete slab is positioned with a gap between it and the one of the reinforcing steel precast concrete slabs. The method is characterized in that concrete is poured into the gap to form a post-cast concrete body, thereby producing a half-precast beam.

[0059] According to this aspect, one of a pair of reinforced precast concrete slabs, each containing a C-shaped set of vertical reinforcing bars, is positioned, the other is moved laterally, and the lower horizontal reinforcing bars, lower hooks, and lower main reinforcing bars are inserted between the upper and lower hooks of the first reinforced precast concrete slab. The other is then lowered downward, overlapping the upper horizontal reinforcing bars and the lower horizontal reinforcing bars, forming a gap between the first reinforced precast concrete slab and the second reinforced precast concrete slab. This allows for automatic reinforcement arrangement after the pair of reinforced precast concrete slabs is positioned, eliminating or reducing the need for separate reinforcement arrangement work. Furthermore, by using the pair of reinforced precast concrete slabs as side frames and pouring concrete into the gap between them to form a post-cast concrete body, the labor required for formwork installation and removal can be reduced.

[0060] Another aspect of the method for manufacturing a half precast beam according to the present invention is to Among the upper end main reinforcements attached to the upper horizontal reinforcements of each of the pair of reinforced concrete slabs, the upper end main reinforcements arranged at the lap positions of both upper horizontal reinforcements are attached only below one of the upper horizontal reinforcements, and are not attached below the other upper horizontal reinforcement, Among the lower end main reinforcements attached to the lower transverse reinforcements of each of the pair of reinforced concrete slabs, the lower end main reinforcements arranged at the lap positions of both the lower transverse reinforcements are attached only above one of the lower transverse reinforcements, and are not attached above the other lower transverse reinforcement, The upper horizontal reinforcements are overlapped with each other and the lower horizontal reinforcements are overlapped with each other, so that the upper main reinforcements are aligned horizontally at equal or approximately equal intervals, and the lower main reinforcements are aligned horizontally at equal or approximately equal intervals.

[0061] According to this aspect, of the upper main reinforcements (or lower main reinforcements) attached to each upper transverse reinforcement (or lower transverse reinforcement) of a pair of reinforced concrete slabs, the upper main reinforcements (or lower main reinforcements) arranged at the overlap positions of both upper transverse reinforcements (or lower transverse reinforcements) are attached only below (or above) one of the upper transverse reinforcements (or one lower transverse reinforcement), and are not attached below (or above) the other upper transverse reinforcement (or the other lower transverse reinforcement). When the upper transverse reinforcements are overlapped and the lower transverse reinforcements are overlapped, the multiple upper main reinforcements are aligned horizontally at equal or approximately equal intervals, and the multiple lower main reinforcements are aligned horizontally at equal or approximately equal intervals. This prevents interference between the multiple upper main reinforcements at the overlap positions of the upper transverse reinforcements and the multiple lower main reinforcements at the overlap positions of the lower transverse reinforcements, and allows the upper and lower main reinforcements to be aligned horizontally at equal or approximately equal intervals.

[0062] Another aspect of the method for manufacturing a half precast beam according to the present invention is to The precast concrete slab comprises a vertical slab extending in the vertical direction and a lower horizontal slab extending in the horizontal direction from a lower end of the vertical slab, and a plurality of the lower end main reinforcements are embedded in the lower horizontal slab, By abutting the end faces of the lower horizontal plates of the pair of reinforcing steel precast concrete slabs, both vertical plates and both lower horizontal plates form a U-shaped formwork with a cross-sectional shape perpendicular to the longitudinal direction that opens upward, The method is characterized in that concrete is poured into the formwork to form the post-cast concrete body.

[0063] According to this embodiment, the precast concrete slab comprises a vertical slab extending vertically and a lower horizontal slab extending horizontally from its lower end, and by abutting the end faces of the lower horizontal slabs of a pair of reinforced concrete slabs, a U-shaped formwork is formed with a cross-sectional shape perpendicular to the longitudinal direction that opens upward.This means that the entire formwork, including the side frames and lower frame, is formed by a pair of reinforced precast concrete slabs, completely eliminating the need to separately install the formwork (such as the lower frame, which is a component of the formwork) or to demold the formwork.As the formwork is U-shaped and opens upward and has a lower frame, the entire formwork can stand on its own.

[0064] Another aspect of the method for manufacturing a half precast beam according to the present invention is to At least one of the lower hooks of the plurality of reinforcing bars included in one of the reinforcing bar precast concrete slabs that is positioned first is a long lower hook that is longer than the length of the upper hooks of all of the reinforcing bars included in the other reinforcing bar precast concrete slab that is positioned later, When lowering the other reinforcing bar precast concrete slab downward, the long lower hook is passed through the lower cross bars of the other reinforcing bar precast concrete slab in advance, and then both upper cross bars are overlapped and both lower cross bars are overlapped, or At least one of the upper hooks of the plurality of reinforcing bars provided on the other reinforcing bar precast concrete slab to be positioned subsequently is a long upper hook that is longer than the length of the lower hooks of all of the reinforcing bars provided on the one reinforcing bar precast concrete slab to be positioned first, When the other reinforcing steel precast concrete slab is lowered downward, the long upper hook is first passed between the upper horizontal bars of one of the reinforcing steel precast concrete slabs, and then the upper horizontal bars of both slabs are overlapped and the lower horizontal bars of both slabs are overlapped.

[0065] According to this aspect, at least one of the lower hooks of the multiple reinforcing bars of one reinforced precast concrete slab that is positioned first is a long lower hook that is longer than the length of all of the upper hooks of the reinforcing bars of the other reinforced precast concrete slab that is positioned later.By doing so, when lowering the other reinforced precast concrete slab, the long lower hook can be passed first between the multiple lower horizontal bars of the other reinforced precast concrete slab, and the other lower hooks of the other reinforced precast concrete slab that is positioned later can be passed smoothly between the multiple lower horizontal bars of the one reinforced precast concrete slab that is positioned first.

[0066] Similarly, by making at least one of the upper hooks of the multiple reinforcing bars of the other reinforced precast concrete slab that is positioned later a long upper hook that is longer than the length of all of the lower hooks of the reinforcing bars of the one reinforced precast concrete slab that is positioned first, when the other reinforced precast concrete slab is lowered downward, the long upper hook can be passed first between the multiple upper horizontal bars of the one reinforced precast concrete slab, and the other upper hooks of the other reinforced precast concrete slab that is positioned later can be passed smoothly between the multiple upper horizontal bars of the one reinforced precast concrete slab that is positioned first.

[0067] Here, "at least one or more of the lower hooks" includes a configuration in which only one lower hook is longer than all of the upper hooks of the reinforced concrete slab that will be positioned later, a configuration in which multiple lower hooks are longer than all of the upper hooks of the reinforced concrete slab that will be positioned later but the lengths of the multiple long lower hooks are different, and a configuration in which all of the lower hooks are longer than all of the upper hooks of the reinforced concrete slab that will be positioned later.Similar variations are also included in "at least one or more upper hooks."

[0068] Furthermore, for example, if at least one of the lower hooks of the multiple reinforcing bars of a reinforced precast concrete slab that is positioned first is a long lower hook, the other lower hooks that are not long lower hooks, and the upper and lower hooks of the multiple reinforcing bars of a reinforced precast concrete slab that is positioned later, etc., hooks other than the long lower hooks have the minimum required length.

[0069] In another aspect of the method for manufacturing a half precast beam according to the present invention, In the embodiment having the long bottom hook, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the bottom hook of one of the reinforcing bars is the longest first long bottom hook, and the bottom hook of the other reinforcing bar is the next longest second long bottom hook, The first long lower hook is passed through between the plurality of lower hooks provided on the other reinforcing bar precast concrete slab, and then the second long lower hook is passed through between the plurality of lower hooks provided on the other reinforcing bar precast concrete slab, or In the embodiment having the long upper hook, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the upper hook of one of the reinforcing bars is the longest first long upper hook, and the upper hook of the other reinforcing bar is the next longest second long upper hook, The method is characterized in that the first long upper hook is first passed between the multiple upper hooks provided on one of the reinforcing steel precast concrete slabs, and then the second long upper hook is passed between the multiple upper hooks provided on one of the reinforcing steel precast concrete slabs.

[0070] According to this embodiment, in a configuration having long bottom hooks, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the bottom hook of one reinforcing bar is the longest, the first long bottom hook, and the bottom hook of the other reinforcing bar is the next longest, the second long bottom hook.The first long bottom hook is first passed between the multiple bottom hooks of the other reinforcing bar that will be positioned later, and then the second long bottom hook is passed between the multiple bottom hooks of the other reinforcing bar precast concrete slab.As a result, the bottom hooks located at both ends of the bottom hooks of the multiple reinforcing bars (the first long bottom hook and the second long bottom hook) are first passed between the multiple bottom hooks of the other reinforcing bar precast concrete slab, and therefore the other bottom hooks between the first long bottom hook and the second long bottom hook can be automatically and smoothly passed between the multiple bottom hooks of the other reinforcing bar precast concrete slab.

[0071] Similarly, in a configuration having long upper hooks, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the upper hook of one of the reinforcing bars is the longest, the first long upper hook, and the upper hook of the other reinforcing bar is the next longest, the second long upper hook.The first long upper hook is first passed between the multiple upper hooks of one of the reinforcing bars that has been positioned first, and then the second long upper hook is passed between the multiple upper hooks of one of the reinforcing bars.As a result, the upper hooks located at both ends of the multiple upper hooks of the reinforcing bars (the first long upper hook and the second long upper hook) are first passed between the multiple upper hooks of one of the reinforcing bars.As a result, the other upper hooks between the first long upper hook and the second long upper hook can be automatically and smoothly passed between the multiple upper hooks of one of the reinforcing bars. [Effects of the Invention]

[0072] As can be understood from the above explanation, according to the half precast beam and its manufacturing method of the present invention, the precast concrete slabs that make up the half precast beam can reduce the labor required for installing and removing formwork, while also reducing the labor required for reinforcing beam reinforcement, thereby providing a high-quality half precast beam with high overall rigidity and integrity. [Brief explanation of the drawings]

[0073] [Figure 1] FIG. 1 is a perspective view of a pair of precast concrete slabs with steel bars, which constitute an example of a half precast beam according to an embodiment. [Figure 2] 1A to 1E are process diagrams showing a manufacturing method for an example of a half precast beam according to an embodiment of the present invention, together with a longitudinal cross-sectional view perpendicular to the longitudinal direction of an example of a half precast beam according to an embodiment of the present invention. [Figure 3] These are process diagrams, in the order of (a) to (e), of a method for manufacturing another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of another example of a half precast beam according to an embodiment. [Figure 4] These are process diagrams, in the order of (a) to (d), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 5] These are process diagrams, in the order of (a) to (d), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 6] These are process diagrams, in the order of (a) to (d), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 7] These are process diagrams, in the order of (a) to (c), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 8] This is an oblique view of a pair of reinforced precast concrete slabs that constitute yet another example of a half precast beam according to an embodiment. [Figure 9] These are process diagrams, in the order of (a) to (e), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 10] 10(a) and 10(b) are both perspective views of a reinforced precast concrete slab constituting yet another example of a half precast beam according to an embodiment. [Figure 11] 10(a) to 10(c) are process diagrams showing still another example of a method for manufacturing a half precast beam according to an embodiment of the present invention. [Figure 12] 10(a) to 10(d) are process diagrams showing still another example of a method for manufacturing a half precast beam according to an embodiment of the present invention. [Figure 13]This is an oblique view of a precast concrete slab with steel bars that is positioned in advance, which constitutes yet another example of a half precast beam according to an embodiment. [Figure 14] 10(a) to 10(d) are process diagrams showing still another example of a method for manufacturing a half precast beam according to an embodiment of the present invention. [Figure 15] These are process diagrams, in the order of (a) to (e), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 16] This is an oblique view of a pair of reinforced precast concrete slabs that constitute yet another example of a half precast beam according to an embodiment. [Figure 17] These are process diagrams, in the order of (a) to (e), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 18] These are process diagrams, in the order of (a) to (e), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 19] (a) and (b) are both vertical cross-sectional views perpendicular to the longitudinal direction of a pair of reinforced precast concrete slabs assembled together, constituting yet another example of a half precast beam according to an embodiment of the present invention. [Figure 20] This is an oblique view of a pair of reinforced precast concrete slabs that constitute yet another example of a half precast beam according to an embodiment. [Figure 21] These are process diagrams, in the order of (a) to (c), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. [Figure 22]These are process diagrams, in the order of (a) to (c), of a method for manufacturing yet another example of a half precast beam according to an embodiment, along with a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0074] Hereinafter, an example of a half precast beam and a manufacturing method thereof according to an embodiment will be described with reference to the accompanying drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[0075] [Half precast beam according to the embodiment and its manufacturing method] 1 to 22, several examples of half precast beams according to the embodiment and methods for manufacturing the same will be described. Here, FIG. 1 is a perspective view of a pair of reinforcing steel precast concrete slabs that constitute an example of a half precast beam according to the embodiment. Also, FIG. 2 is a process chart of a manufacturing method for an example of a half precast beam according to the embodiment, in the order of (a) to (e), which also shows a longitudinal cross-sectional view of the example of a half precast beam according to the embodiment, perpendicular to the longitudinal direction.

[0076] The half precast beam 100 shown in Figure 2(e) has a pair of reinforced precast concrete slabs 50 arranged with a gap G between them, and a post-cast concrete body 60 provided in the gap G.

[0077] As shown in FIG. 1, a reinforced precast concrete slab 50 is formed by attaching a plurality of reinforcing bars 10 to a precast concrete slab 20 at intervals in the longitudinal direction thereof.

[0078] The reinforcing bar 10 is made up of vertical bars 11, upper horizontal bars 12 that bend at the top ends of the vertical bars 11 and extend horizontally, upper hooks 13 that bend at the ends of the upper horizontal bars 12 and extend downward, lower horizontal bars 14 that bend at the bottom ends of the vertical bars 11 and extend horizontally, and lower hooks 15 that bend at the ends of the lower horizontal bars 14 and extend upward, forming a C-shape with an open portion 10a. Both the upper hooks 13 and lower hooks 15 in the illustrated example are 90-degree hooks.

[0079] The precast concrete slab 20 has a vertical slab 22 extending in the vertical direction, and the vertical bars 11 extending in the vertical direction are embedded in the vertical slab 22, thereby attaching the reinforcing bars 10 to the precast concrete slab 20.

[0080] Although not shown in the drawings, the thickness of the precast concrete slab may be increased so that some of the upper end main reinforcements and some of the lower end main reinforcements (for example, one of each) are embedded inside the precast concrete slab. In a configuration in which the thickness of the precast concrete slab is increased, it is preferable to further embed some of the upper end main reinforcements 30 and the lower end main reinforcements 40 in addition to the vertical reinforcements 11, as this can prevent cracking of the precast concrete slab that constitutes the reinforced precast concrete slab before the half precast beam is fabricated.

[0081] A plurality of upper main reinforcements 30 extending in the longitudinal direction are attached below the plurality of upper cross reinforcements 12, and a plurality of lower main reinforcements 40 extending in the longitudinal direction are attached above the plurality of lower cross reinforcements 14. By attaching a plurality of upper main reinforcements 30 and lower main reinforcements 40 to the precast concrete slab 20 to which a plurality of reinforcing bars 10 are attached, a reinforced precast concrete slab 50 is formed.

[0082] Here, the entire reinforced precast concrete slab 50 shown in the figure may be manufactured in a factory or the like, transported to the site and installed at the installation location, or the precast concrete slab 20 and the upper main reinforcement 30 and lower main reinforcement 40 may be transported to the site without the upper main reinforcement 30 and lower main reinforcement 40 attached (everything other than the upper main reinforcement 30 and lower main reinforcement 40 may be manufactured in a factory or the like), and after the precast concrete slab 20 is installed at the installation location on site, the upper main reinforcement 30 and lower main reinforcement 40 may be attached to form the reinforced precast concrete slab 50.

[0083] The following description will be given assuming that the half precast beam to be manufactured is a beam for the upper floor. Regarding the manufacturing method of the illustrated example, first, as shown in Figure 2(a), a lower frame 91 is installed at the installation position of the beam, and one of a pair of reinforced precast concrete slabs 50 (the left reinforced precast concrete slab 50 in the illustrated example) is positioned on the lower frame 91 in an orientation such that the open portion 10a of each reinforcing bar 10 faces the side of the reinforced precast concrete slab 50 (the right reinforced precast concrete slab 50 in the illustrated example) that will be installed next.

[0084] Here, the reinforced precast concrete slab 50 on the left side, which is installed first, has four upper main reinforcements 30 attached to the upper horizontal reinforcements 12 at equal or approximately equal intervals in the horizontal direction, and three lower main reinforcements 40 attached to the lower horizontal reinforcements 14 at equal or approximately equal intervals in the horizontal direction.

[0085] On the other hand, the reinforced precast concrete slab 50 on the right side, which is installed later, has three upper main reinforcements 30 attached to the multiple upper cross reinforcements 12 at equal or approximately equal intervals in the horizontal direction, and four lower main reinforcements 40 attached to the multiple lower cross reinforcements 14 at equal or approximately equal intervals in the horizontal direction.

[0086] As will be explained below, a pair of reinforced concrete slabs 50 have one upper main reinforcement 30 arranged between both upper hooks 13 and one lower main reinforcement 40 arranged between both lower hooks 15, so that the reinforcing bars 10 of both slabs are overlapped. However, in this case, to prevent the upper main reinforcement 30 from interfering with each other at the overlap position of both reinforced concrete slabs 50 and the lower main reinforcement 40 from interfering with each other at the overlap position of one of the reinforced concrete slabs 50, the installation of the upper main reinforcement 30 and the lower main reinforcement 40 is omitted (in the illustrated example, one upper main reinforcement 30 and one lower main reinforcement 40 are omitted).

[0087] In the illustrated example, the installation of the upper end main reinforcement 30 at the lap position from the left-side reinforced precast concrete slab 50 is omitted, and the installation of the lower end main reinforcement 40 at the lap position from the right-side reinforced precast concrete slab 50 is omitted, but it is also possible to omit the installation of the upper end main reinforcement 30 and the lower end main reinforcement 40 at the lap position of one of the left-side and right-side reinforced precast concrete slabs 50, and have both the upper end main reinforcement 30 and the lower end main reinforcement 40 installed at the lap position of the other precast concrete slab 50.

[0088] However, if one of the reinforced precast concrete slabs 50 does not have both the upper end main reinforcement 30 and the lower end main reinforcement 40 at the lap position, the amount of reinforcement in the left and right reinforced precast concrete slabs 50 will differ, making one of the left and right reinforced precast concrete slabs 50 too heavy.In addition, since the reinforced precast concrete slab 50 is one of the heaviest components to be lifted by a crane, in order to make the weight of the reinforced precast concrete slabs 50 as light as possible, it is preferable to omit one of the upper end main reinforcement and one of the lower end main reinforcement at the lap position, as in the example shown in the figure, so that the amount of reinforcement in a pair of reinforced precast concrete slabs 50 is approximately the same.

[0089] Next, as shown in Figure 2(b), the other precast concrete slab 50 (the reinforced precast concrete slab 50 on the right in the illustrated example) is moved laterally in the X1 direction with the open portion 10a of each reinforcing bar 10 facing the reinforced precast concrete slab 50 that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the reinforced precast concrete slab 50 on the left, and the lateral movement of the upper hook 13 of the right reinforced precast concrete slab 50 is stopped at the position where it has passed through the one upper main reinforcement 30 on the right side of the reinforced precast concrete slab 50 on the left.

[0090] Next, as shown in Figure 2(c), the right-side reinforced precast concrete slab 50 is lowered downward in the X2 direction, moving the upper hook 13 downward so as to straddle one of the upper main reinforcement bars 30 at the lap position.

[0091] As shown in Figure 2(d), by completely lowering the right-side reinforced precast concrete slab 50 and placing it on the lower frame 91, both upper horizontal bars 12 overlap each other, and both lower horizontal bars 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup bar 10'. A plurality of (seven in the illustrated example) upper main bars 30 are arranged at equal or approximately equal intervals in the horizontal direction for both upper horizontal bars 12 that overlap each other, and the central upper main bar 30 is surrounded by left and right upper hooks 13. Similarly, a plurality of (seven in the illustrated example) lower main bars 40 are arranged at equal or approximately equal intervals in the horizontal direction for both lower horizontal bars 14 that overlap each other, and the central lower main bar 40 is surrounded by left and right lower hooks 15. The reinforcement is automatically arranged, and a gap G is formed between the pair of reinforced precast concrete slabs 50.

[0092] Here, the overlapping upper horizontal reinforcements 12 and lower horizontal reinforcements 14 may be connected by bundling or the like, or they may not be connected. If the overlapping points are connected, the integrity of the stirrup reinforcement 10' can be further improved, and if the overlapping points are not connected, the manufacturing efficiency of the half precast beam can be further improved.

[0093] In this way, when a pair of reinforced precast concrete slabs 50 are installed with a gap G formed between them, the beam reinforcement is arranged at the same time, thereby eliminating or reducing the labor required for the beam reinforcement arrangement work.

[0094] Next, as shown in Figure 2(e), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100 having a pair of reinforced precast concrete slabs 50 and a post-cast concrete body 60.

[0095] In the manufacturing method shown in the figure, the precast concrete slab 20 functions as a formwork (side frame) when forming the post-cast concrete body 60, while being left in place as a component of the half precast beam 100, eliminating the need to install and remove the side frames, thereby reducing the labor required for installing and removing the formwork.

[0096] In this way, the method for manufacturing half precast beams using a pair of reinforcing steel precast concrete slabs 50 can eliminate or reduce the labor required for installing and removing formwork, while also eliminating the need for beam reinforcement work, resulting in a manufacturing method that is excellent in the manufacturability (or constructability) of the beams and can improve quality.

[0097] Furthermore, by forming a ring-shaped stirrup bar 10' by wrapping a portion of a pair of reinforced precast concrete slabs 50 together with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100 with high overall rigidity and integrity can be formed.

[0098] Furthermore, since both of a pair of reinforced concrete slabs 50 have the same shape and configuration except for the number of upper end main reinforcements 30 and lower end main reinforcements 40, the mass productivity of the reinforced concrete slabs 50 can be improved.

[0099] In the illustrated example, the reinforced precast concrete slab 50 has the upper end main reinforcements 30 and the lower end main reinforcements 40 attached beforehand when it is installed at the installation location, but a manufacturing method may also be used in which a reinforced precast concrete slab is prepared without the upper end main reinforcements 30 and the lower end main reinforcements 40, and after both the upper end main reinforcements 30 and the lower end main reinforcements 40 are installed, the upper end main reinforcements 30 and the lower end main reinforcements 40 are arranged. With this construction method, although the work of arranging the upper end main reinforcements 30 and the lower end main reinforcements 40 on-site is required, the weight of the reinforced precast concrete slab can be reduced, which leads to the downsizing of heavy machinery used to lift the reinforced precast concrete slab.

[0100] Next, a method for manufacturing another example of a half precast beam according to the embodiment will be described with reference to Fig. 3. Here, Fig. 3(a) to (e) are, in that order, process diagrams of the method for manufacturing another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of the other example of a half precast beam according to the embodiment.

[0101] A pair of reinforced precast concrete slabs 50A applicable to the manufacturing method shown in Figure 3 differs from the reinforced precast concrete slabs 50 comprising the precast concrete slabs 20 in that the precast concrete slabs 20A comprise vertical slabs 22 extending vertically and upper horizontal slabs 24 and lower horizontal slabs 26 extending horizontally from the upper and lower ends of the vertical slabs 22, respectively, and in that one upper main reinforcement 30 and one lower main reinforcement 40 are embedded in each of the upper horizontal slabs 24 and lower horizontal slabs 26.

[0102] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 3(a), a lower frame 91 is installed at the installation position of the beam, and one of a pair of reinforced precast concrete slabs 50A (the left reinforced precast concrete slab 50A in the illustrated example) is positioned on top of the lower frame 91 in an orientation in which the open portion 10a of each reinforcing bar 10 faces the side of the reinforced precast concrete slab 50A (the right reinforced precast concrete slab 50 in the illustrated example) that will be installed later.

[0103] Next, as shown in Figure 3(b), the other precast concrete slab 50A (the reinforced precast concrete slab 50A on the right in the illustrated example) is moved laterally in the X3 direction with the open portion 10a of each reinforcing bar 10 facing the reinforced precast concrete slab 50A that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the reinforced precast concrete slab 50A on the left, and the lateral movement of the upper hook 13 of the reinforced precast concrete slab 50A on the right is stopped at the position where it has passed through the one upper main reinforcement 30 on the right side of the reinforced precast concrete slab 50A on the left.

[0104] Next, as shown in Figure 3(c), the right-side reinforced precast concrete slab 50A is lowered downward in the X4 direction, moving the upper hook 13 downward so as to straddle one upper main reinforcement 30 at the lap position.

[0105] As shown in Figure 3(d), when the right-side reinforced precast concrete slab 50A is completely lowered and placed on the lower frame 91, both upper horizontal bars 12 overlap each other, and both lower horizontal bars 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup bar 10'. A plurality of (seven in the illustrated example) upper main bars 30 are arranged at equal or approximately equal intervals in the horizontal direction on both overlapping upper horizontal bars 12, and the central upper main bar 30 is surrounded by left and right upper hooks 13. Similarly, a plurality of (seven in the illustrated example) lower main bars 40 are arranged at equal or approximately equal intervals in the horizontal direction on both overlapping lower horizontal bars 14, and the central lower main bar 40 is surrounded by left and right lower hooks 15. The reinforcement is automatically arranged, and a gap G is formed between the pair of reinforced precast concrete slabs 50A.

[0106] Next, as shown in Figure 3(e), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100A having a pair of reinforced precast concrete slabs 50A and a post-cast concrete body 60.

[0107] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0108] Furthermore, by providing the precast concrete slab 20A with the lower horizontal slab 26, a stable upright posture can be formed when installed on the lower frame 91.

[0109] Furthermore, by forming a ring-shaped stirrup bar 10' by overlapping a portion of a pair of reinforced precast concrete slabs 50A with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100A with high overall rigidity and integrity can be formed.

[0110] Furthermore, since the precast concrete slab 20A is provided with upper horizontal slabs 24 and lower horizontal slabs 26 extending laterally, an engagement structure can be formed with the pair of upper horizontal slabs 24 and the pair of lower horizontal slabs 26 and the post-cast concrete body 60 provided in the gap G therebetween, thereby achieving even greater integration between the pair of reinforced precast concrete slabs 50A and the post-cast concrete body 60.

[0111] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 4. Here, Fig. 4(a) to (d) are, in that order, process diagrams of the method for manufacturing yet another example of a half precast beam according to the embodiment, and are also diagrams showing vertical cross-sectional views perpendicular to the longitudinal direction of yet another example of a half precast beam according to the embodiment.

[0112] A pair of reinforced precast concrete slabs 50B applicable to the manufacturing method shown in Figure 4 differs from the reinforced precast concrete slabs 50 comprising the precast concrete slabs 20 in that one precast concrete slab 20B comprises a vertical slab 22 and a lower horizontal slab 27A extending horizontally from the lower end of the vertical slab 22, and the other precast concrete slab 20C comprises a vertical slab 22 and a lower horizontal slab 27B extending horizontally from the lower end of the vertical slab 22, and in that all of the lower main reinforcements 40 are embedded in one lower horizontal slab 27A, and three of the four lower main reinforcements 40 are embedded in the other lower horizontal slab 27B.

[0113] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 4(a), one of the reinforced precast concrete slabs 50B is positioned on the lower frame 91 with the open portions 10a of each reinforcing bar 10 facing the reinforced precast concrete slab 50C that will be installed later, and the other precast concrete slab 50C is moved laterally in the X5 direction with the open portions 10a of each reinforcing bar 10 facing the reinforced precast concrete slab 50B that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the left reinforced precast concrete slab 50B, and the lateral movement of the upper hook 13 of the right reinforced precast concrete slab 50C is stopped at a position where it has passed through the one upper main reinforcement 30 on the right side of the left reinforced precast concrete slab 50B.

[0114] Next, as shown in Figure 4(b), the right-side reinforced precast concrete slab 50C is lowered downward in the X6 direction, moving the upper hook 13 downward so as to straddle one upper main reinforcement 30 at the lap position.

[0115] As shown in Figure 4(c), by completely lowering the right-side reinforced precast concrete slab 50C and placing it on the lower frame 91, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other to form a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup reinforcement 10', and multiple (seven in the illustrated example) upper end main reinforcements 30 are arranged at equal or approximately equal intervals in the horizontal direction relative to both overlapping upper horizontal reinforcements 12, and the central upper end main reinforcement 30 is surrounded by upper hooks 13 on the left and right.

[0116] Meanwhile, the end faces of both lower horizontal slabs 27A, 27B abut against each other, and the other lower horizontal reinforcing bar 14, part of the lower hook 15, and one bottom main reinforcing bar 40 are accommodated in the recess 27a of the lower horizontal slab 27A, forming a gap G between the pair of reinforced precast concrete slabs 50B, 50C. In this state, three bottom main reinforcing bars 40 are embedded at equal or approximately equal intervals in each of the lower horizontal slabs 27A, 27B, and one bottom main reinforcing bar 40 is further disposed at equal or approximately equal intervals between them.

[0117] As shown in Figure 4(c), when a pair of reinforcing steel precast concrete slabs 50B, 50C are installed, by forming a U-shaped formwork with an upwardly opening cross section perpendicular to the longitudinal direction, the entire formwork including the side frames and bottom frame is formed by the pair of reinforcing steel precast concrete slabs 50B, 50C, completely eliminating the need to separately install the formwork (its components such as the bottom frame) and the need to remove the formwork. Here, the bottom frame 91 shown in Figure 4 is not a bottom frame that forms the formwork, but is used as a platform on which the pair of reinforcing steel precast concrete slabs 50B, 50C are placed.

[0118] Next, as shown in Figure 4(d), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100B having a pair of reinforced precast concrete slabs 50B, 50C and a post-cast concrete body 60.

[0119] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0120] Furthermore, by forming a ring-shaped stirrup bar 10' by overlapping a portion of a pair of reinforced precast concrete slabs 50B, 50C with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100B with high overall rigidity and integrity can be formed.

[0121] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 5. Here, Fig. 5(a) to (d) are, in that order, process diagrams of a method for manufacturing yet another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of yet another example of a half precast beam according to the embodiment.

[0122] A pair of reinforced precast concrete slabs 50D applied to the manufacturing method shown in Figure 5 differs from reinforced precast concrete slabs 50 in that it has reinforcement bars 10A inside the C-shaped reinforcement bars, with core bars 16 engaged with the upper main bars 30 and the lower main bars 40.

[0123] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 5(a), one of the reinforced precast concrete slabs 50D is positioned on the lower frame 91 with the open portion 10a of each reinforcing bar 10A facing the side of the reinforced precast concrete slab 50D that will be installed later, and the other precast concrete slab 50D is moved laterally in the X7 direction with the open portion 10a of each reinforcing bar 10A facing the side of the reinforced precast concrete slab 50D that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the left reinforced precast concrete slab 50D, and the lateral movement of the upper hook 13 of the right reinforced precast concrete slab 50D is stopped at a position where it has passed through the one upper main reinforcement 30 on the right side of the left reinforced precast concrete slab 50D.

[0124] Next, as shown in Figure 5(b), the right-side reinforced precast concrete slab 50D is lowered downward in the X8 direction, moving the upper hook 13 downward so as to straddle one upper main reinforcement 30 at the lap position.

[0125] As shown in Figure 5(c), by completely lowering the right-side reinforced precast concrete slab 50D and placing it on the lower frame 91, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup reinforcement 10A', and a plurality of (seven in the illustrated example) upper main reinforcements 30 are arranged at equal or approximately equal intervals in the horizontal direction for both overlapping upper horizontal reinforcements 12, and the central upper main reinforcement 30 is surrounded by left and right upper hooks 13. Similarly, a plurality of (seven in the illustrated example) lower main reinforcements 40 are arranged at equal or approximately equal intervals in the horizontal direction for both overlapping lower horizontal reinforcements 14, and the central lower main reinforcement 40 is surrounded by left and right lower hooks 15. In this way, the reinforcement is automatically arranged, and a gap G is formed between the pair of reinforced precast concrete slabs 50D.

[0126] Next, as shown in Figure 5(d), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100C having a pair of reinforcing steel precast concrete slabs 50D and a post-cast concrete body 60.

[0127] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0128] Furthermore, by forming a ring-shaped stirrup reinforcement 10A' by wrapping a portion of each reinforcement bar 10A of a pair of reinforced precast concrete slabs 50D together with the open portions 10a of both reinforcement bars 10A facing the other side, a half precast beam 100C with high overall rigidity and integrity can be formed.

[0129] Furthermore, in the half precast beam 100C, a core bar 16 is further provided inside the C-shaped reinforcement bar 10A, which is engaged with the upper main reinforcement bar 30 and the lower main reinforcement bar 40, thereby providing shear reinforcement through the core bar 16.

[0130] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 6. Here, Fig. 6(a) to (d) are, in that order, process diagrams of the method for manufacturing yet another example of a half precast beam according to the embodiment, and are also diagrams showing vertical cross-sectional views perpendicular to the longitudinal direction of yet another example of a half precast beam according to the embodiment.

[0131] A pair of reinforced precast concrete slabs 50E applied to the manufacturing method shown in Figure 6 differs from the reinforced precast concrete slabs 50 equipped with reinforcing bars 10 in that the two lower main reinforcements 40 are not attached at the lap position of one lower horizontal reinforcement 14, and the two upper main reinforcements 30 are not attached at the lap position of the other upper horizontal reinforcement 12, i.e., the pair is equipped with reinforcing bars 10B in which the number of upper main reinforcements 30 and lower main reinforcements 40 at the lap position is two (an example of multiple reinforcements) instead of one.

[0132] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 6(a), one of the reinforced concrete slabs 50E is positioned on the bottom frame 91 with the open portions 10a of each reinforcing bar 10B facing the side of the reinforced concrete slab 50E that will be installed later, and the other reinforced concrete slab 50E is moved laterally in the X9 direction with the open portions 10a of each reinforcing bar 10B facing the side of the reinforced concrete slab 50E that will be installed first, and its lower cross bar 14, lower hook 15 and two lower main bars 40 are passed between the upper hook 13 and lower hook 15 of the left reinforced precast concrete slab 50E, and the lateral movement of the upper hook 13 of the right reinforced precast concrete slab 50E is stopped at a position where it has passed through the two upper main bars 30 on the right side of the left reinforced precast concrete slab 50D.

[0133] Next, as shown in Figure 6(b), the right-side reinforced precast concrete slab 50E is lowered downward in the X10 direction, moving the upper hook 13 downward so as to straddle the two upper main reinforcements 30 at the lap position.

[0134] As shown in Figure 6(c), when the right-side reinforced precast concrete slab 50E is completely lowered and placed on the lower frame 91, both upper horizontal bars 12 overlap each other, and both lower horizontal bars 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup bar 10B'. A plurality of (six in the illustrated example) upper main bars 30 are arranged at equal or approximately equal intervals in the horizontal direction between both overlapping upper horizontal bars 12, and the two central upper main bars 30 are surrounded by left and right upper hooks 13. Similarly, a plurality of (six in the illustrated example) lower main bars 40 are arranged at equal or approximately equal intervals in the horizontal direction between both overlapping lower horizontal bars 14, and the two central lower main bars 40 are surrounded by left and right lower hooks 15. In this way, the reinforcement is automatically arranged, and a gap G is formed between the pair of reinforced precast concrete slabs 50E.

[0135] Next, as shown in Figure 6(d), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100D having a pair of reinforcing steel precast concrete slabs 50E and a post-cast concrete body 60.

[0136] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0137] Furthermore, by forming a ring-shaped stirrup bar 10B' by overlapping a portion of a pair of reinforced precast concrete slabs 50E with the open portions 10a of both reinforcing bars 10B facing the other side, a half precast beam 100D with high overall rigidity and integrity can be formed.

[0138] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 7. Here, Fig. 7(a) to (c) are, in that order, process diagrams of a method for manufacturing yet another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of yet another example of a half precast beam according to the embodiment.

[0139] A pair of reinforced precast concrete slabs 50F, which are applicable to the manufacturing method shown in Figure 7, differ from reinforced precast concrete slabs 50 in that the upper parts of the vertical bars 11 of the reinforcing bars 10 protrude from the upper end of the precast concrete slabs 20, and the reinforcing bars 10 are attached at a relatively high position relative to the precast concrete slabs 20.

[0140] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 7(a), a pair of reinforced precast concrete slabs 50F are installed with the open portions 10a of both reinforcing bars 10 facing the other reinforced precast concrete slab 50F, and both upper horizontal bars 12 overlap each other and both lower horizontal bars 14 overlap each other to form a ring-shaped (rectangular frame-shaped in the illustrated example) stirrup bar 10', and the tops of both reinforcing bars 10 and multiple (seven in the illustrated example) upper main bars 30 protrude above the pair of precast concrete slabs 20.

[0141] Next, as shown in Figure 7(b), floor frames 92 are installed on the left and right sides of the pair of precast concrete slabs 20, and upper and lower floor reinforcement bars 93 are arranged so that they penetrate laterally above the reinforcing bars 10 and above and below the multiple upper main reinforcement bars 30, and further floor reinforcement bars 93 are arranged in a direction perpendicular to this.

[0142] Next, as shown in Figure 7(c), concrete is poured continuously into the gap G between a pair of reinforced precast concrete slabs 50F and into the space above the floor lower frame 92 to form a post-cast concrete body 60 and a concrete floor slab 60A, thereby producing a half precast beam 100E with a floor, which has a pair of reinforced precast concrete slabs 50F, a post-cast concrete body 60, and a concrete floor slab 60A.

[0143] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0144] Furthermore, by forming a ring-shaped stirrup bar 10' by wrapping a portion of a pair of reinforced precast concrete slabs 50F together with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100E with high overall rigidity and integrity can be formed.

[0145] Next, a method for manufacturing yet another example of a half precast beam according to an embodiment will be described with reference to Figures 8 and 9. Here, Figure 8 is a perspective view of a pair of reinforcing steel precast concrete slabs constituting yet another example of a half precast beam according to an embodiment. Also, Figure 9 is a process chart, in the order of (a) to (e), of a method for manufacturing yet another example of a half precast beam according to an embodiment, which also shows a longitudinal cross-sectional view perpendicular to the longitudinal direction of yet another example of a half precast beam according to an embodiment.

[0146] Of the pair of reinforcing bars 50G shown in Figures 8 and 9, the left reinforcing bar 50G has reinforcing bars 10C in multiple stages (two stages in the illustrated example) of stepping bars 17 that are engaged with the vertical bars 11 and the upper hooks 13, multiple upper end main reinforcements 30 are attached to each of the upper horizontal bars 12 and the two stages of stepping bars 17, multiple stages (two stages in the illustrated example) of stepping bars 17 that are engaged with the vertical bars 11 and the lower horizontal bars 14, and multiple lower end main reinforcements 40 are attached to each of the lower horizontal bars 14 and the two stages of stepping bars 17, and the right reinforcing bar In the precast concrete slab 50G, unlike the left side, the reinforcing bars 10C have multiple stages (two stages in the illustrated example) of step reinforcement bars 17 that are engaged with the vertical reinforcement bars 11 and the lower hooks 15, and multiple lower main reinforcements 40 are attached to each of the lower horizontal reinforcement bars 14 and the two stages of step reinforcement bars 17, and have multiple stages (two stages in the illustrated example) of step reinforcement bars 17 that are engaged with the vertical reinforcement bars 11 and the upper horizontal reinforcement bars 12, and multiple upper main reinforcement bars 30 are attached to each of the upper horizontal reinforcement bars 12 and the two stages of step reinforcement bars 17, which is different from a pair of reinforced precast concrete slabs 50 with reinforcing bars 10.

[0147] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 9(a), one of the reinforced precast concrete slabs 50G is positioned on the lower frame 91 with the open portions 10a of each reinforcing bar 10C facing the side of the reinforced precast concrete slab 50G that will be installed later, and the other reinforced precast concrete slab 50G is moved laterally in the X11 direction with the open portions 10a of each reinforcing bar 10C facing the side of the reinforced precast concrete slab 50G that will be installed first, and its lower cross bars 14, lower hooks 15, two rows of stepping bars 17, and 12 lower main bars 40 are passed between the upper hooks 13 and 15 of the left reinforced precast concrete slab 50G, and the upper hook 13 of the right reinforced precast concrete slab 50G is stopped from moving laterally when it has passed through the three upper main bars 30 in the right row of the left reinforced precast concrete slab 50G.

[0148] Next, as shown in Figure 9(b), the right-side reinforced precast concrete slab 50G is lowered downward in the X12 direction, moving the upper hook 13 downward so as to straddle the three upper main reinforcements 30 at the lap position.

[0149] As shown in Figure 9(c), by completely lowering the right-side reinforced precast concrete slab 50G and placing it on the lower frame 91, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other to form a ring-shaped (rectangular frame-shaped in the illustrated example) stirrup reinforcement 10C', and a plurality of upper end main reinforcements 30 (7 reinforcements x 3 rows in the illustrated example) are arranged at equal or approximately equal intervals in the horizontal direction with respect to both upper horizontal reinforcements 12 overlapping each other and the two rows of horizontally aligned setup reinforcements 17, and the center The three upper main reinforcements 30 lined up vertically in the center are surrounded by left and right upper hooks 13, and similarly, multiple (7 reinforcements x 3 rows in the illustrated example) lower main reinforcements 40 are arranged at equal or approximately equal intervals horizontally relative to both lower horizontal reinforcements 14 that overlap each other and the two rows of horizontally lined up reinforcements 17, and the three lower main reinforcements 40 lined up vertically in the center are surrounded by left and right lower hooks 15, so that the reinforcement is automatically arranged and a gap G is formed between a pair of reinforced precast concrete slabs 50G.

[0150] Next, as shown in Figure 9(d), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100F having a pair of reinforced precast concrete slabs 50G and a post-cast concrete body 60.

[0151] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0152] Furthermore, by forming a ring-shaped stirrup reinforcement 10C' by wrapping a portion of each reinforcement bar 10C together with the open portions 10a of both reinforcement bars 10C facing the other side of a pair of reinforced concrete slabs 50G, a half precast beam 100F with high overall rigidity and integrity can be formed.

[0153] Furthermore, the half precast beam 100F has multiple upper end main reinforcements 30 in multiple rows at each stage, and multiple lower end main reinforcements 40 in multiple rows at each stage, thereby forming an even stronger half precast beam.

[0154] Next, a reinforced precast concrete slab that constitutes yet another example of a half precast beam according to an embodiment will be described with reference to Fig. 10. Here, Fig. 10(a) and (b) are both perspective views of a reinforced precast concrete slab that constitutes yet another example of a half precast beam according to an embodiment.

[0155] The reinforced precast concrete slab 50H shown in Figure 10(a) has a configuration in which reinforcing bars 10D with a relatively large cross-sectional diameter are interposed between multiple reinforcing bars 10 attached to the precast concrete slab 20 and aligned in the longitudinal direction.

[0156] The relatively large diameter reinforcing bars 10D can prevent the upper horizontal bars 12 and the lower horizontal bars 14 from sagging due to the weight of the upper main bars 30 and the lower main bars 40, and from shaking when hung by a crane, etc.

[0157] On the other hand, the reinforced precast concrete slab 50I shown in Figure 10(b) has a configuration in which auxiliary bars 18A are arranged so as to straddle the upper horizontal bars 12 and upper hooks 13 to the vertical bars 11, and separate auxiliary bars 18B are arranged so as to straddle the lower horizontal bars 14 and lower hooks 15 to the vertical bars 11, forming reinforcing bars 10E.

[0158] The upper and lower reinforcing bars 18A, 18B can prevent the upper horizontal bars 12 to which the upper end main bars 30 are attached from sagging, and the lower horizontal bars 14 to which the lower end main bars 40 are attached from sagging.

[0159] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 11. Here, Fig. 11(a) to (c) are process diagrams of the method for manufacturing yet another example of a half precast beam according to the embodiment, in that order.

[0160] A pair of reinforced precast concrete slabs 50J applicable to the manufacturing method shown in Figure 11 differs from a reinforced precast concrete slab 50 having reinforcement bars 10 in which both upper hooks 13 and lower hooks 15 are 90-degree hooks in that the upper hooks 13A of the reinforcement bars 10F of one of the reinforced precast concrete slabs 50J are 135-degree hooks and the lower hooks 15 are 90-degree hooks, whereas the upper hooks 13 of the reinforcement bars 10F of the other of the reinforced precast concrete slabs 50J are 90-degree hooks and the lower hooks 15A are 135-degree hooks.

[0161] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 11(a), one of the reinforced precast concrete slabs 50J is positioned on the lower frame 91 with the open portion 10a of each reinforcing bar 10F facing the side of the reinforced precast concrete slab 50J that will be installed later, and the other reinforced precast concrete slab 50J is moved laterally in the X13 direction with the open portion 10a of each reinforcing bar 10F facing the side of the reinforced precast concrete slab 50J that will be installed first, and its lower cross bar 14, lower hook 15A and one lower main reinforcement 40 are passed between the upper hook 13A and lower hook 15 of the left reinforced precast concrete slab 50J, and the upper hook 13 of the right reinforced precast concrete slab 50J is stopped from moving laterally when it passes through the one upper main reinforcement 30 on the right side of the left reinforced precast concrete slab 50J.

[0162] Next, as shown in Figure 11(b), the right-side reinforced precast concrete slab 50J is lowered downward in the X14 direction, moving the upper hook 13 downward so as to straddle one upper main reinforcement 30 at the lap position.

[0163] As shown in Figure 11(c), when the right-side reinforced precast concrete slab 50J is fully lowered and placed on the lower frame 91, both upper horizontal bars 12 overlap each other, and both lower horizontal bars 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup bar 10F'. Multiple (seven in the illustrated example) upper main bars 30 are arranged at equal or approximately equal intervals laterally between the overlapping upper horizontal bars 12, with the central upper main bar 30 surrounded by the left and right upper hooks 13, 13A. Similarly, multiple (seven in the illustrated example) lower main bars 40 are arranged at equal or approximately equal intervals laterally between the overlapping lower horizontal bars 14, with the central lower main bar 40 surrounded by the left and right lower hooks 15, 15A. This automatic reinforcement arrangement forms a gap G between the pair of reinforced precast concrete slabs 50J. Concrete is poured into this gap G to produce a half precast beam (not shown).

[0164] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0165] Furthermore, by forming a ring-shaped stirrup reinforcement 10F' by wrapping a portion of a pair of reinforced precast concrete slabs 50J together with the open portions 10a of both reinforcing bars 10F facing the other side, a half precast beam with high overall rigidity and integrity can be formed.

[0166] Furthermore, the upper end main reinforcement 30 at the lap position is surrounded by the upper hook 13, which is a 90-degree hook, and the upper hook 13A, which is a 135-degree hook, and similarly the lower end main reinforcement 40 at the lap position is surrounded by the lower hook 15, which is a 90-degree hook, and the lower hook 15A, which is a 135-degree hook, thereby improving the stress transferability between the reinforcing bars 10F of a pair of reinforced precast concrete slabs 50J.

[0167] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 12. Here, Fig. 12(a) to (d) are process diagrams, in that order, of the method for manufacturing yet another example of a half precast beam according to the embodiment.

[0168] A pair of reinforced precast concrete slabs 50K applied to the manufacturing method shown in Figure 12 differ from a reinforced precast concrete slab 50J equipped with reinforcement bar 10F in that the upper hook 13A of the reinforcing bar 10G of one of the reinforced precast concrete slabs 50K is a 135-degree hook and the lower hook 15B is a 135-degree hook with its tip bent and extending in a 90-degree direction, while the upper hook 13B of the reinforcing bar 10G of the other reinforced precast concrete slab 50K is a 135-degree hook with its tip bent and extending in a 90-degree direction and the lower hook 15A is a 135-degree hook.

[0169] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 12(a), one of the reinforced precast concrete slabs 50K is positioned on the lower frame 91 with the open portion 10a of each reinforcing bar 10G facing toward the reinforced precast concrete slab 50K that will be installed later, and the other reinforced precast concrete slab 50K is moved laterally in the X15 direction with the open portion 10a of each reinforcing bar 10G facing toward the reinforced precast concrete slab 50K that will be installed first, and its lower cross bar 14, lower hook 15A and one lower main reinforcement 40 are passed between the upper hook 13A and lower hook 15B of the left reinforced precast concrete slab 50K, and the upper hook 13B of the right reinforced precast concrete slab 50K is stopped from moving laterally when it passes through the one upper main reinforcement 30 on the right side of the left reinforced precast concrete slab 50K.

[0170] Next, as shown in Figure 12(b), the right-side reinforced precast concrete slab 50K is lowered downward in the X16 direction, and then further lowered downward in the X17 direction as shown in Figure 12(c), thereby moving the upper hook 13B downward so as to straddle the upper main reinforcement 30 at the lap position. As is clear from Figures 12(b) and 12(c), the upper hook 13B and the lower hook 15B have portions 13a, 15a at the tips of the 135-degree hooks that are bent 90 degrees. As a result, by sliding the upper hook 13B and the lower hook 15B vertically along the other 135-degree hook, that is, the upper hook 13A or the lower hook 15A, a lap position can be formed in which one upper main reinforcement 30 or one lower main reinforcement 40 is sandwiched between the two 135-degree hooks, as shown in Figure 12(d).

[0171] As shown in Figure 12(d), when the right-side reinforced precast concrete slab 50K is fully lowered and placed on the lower frame 91, the upper horizontal reinforcements 12 and the lower horizontal reinforcements 14 overlap, forming a ring-shaped (rectangular frame-shaped) stirrup reinforcement 10G'. Multiple (seven) upper main reinforcements 30 are arranged at equal or approximately equal intervals across the overlapping upper horizontal reinforcements 12, with the central upper main reinforcement 30 surrounded by left and right upper hooks 13A and 13B. Similarly, multiple (seven) lower main reinforcements 40 are arranged at equal or approximately equal intervals across the overlapping lower horizontal reinforcements 14, with the central lower main reinforcement 40 surrounded by left and right lower hooks 15A and 15B. This automatic reinforcement arrangement forms a gap G between the pair of reinforced precast concrete slabs 50K. Concrete is poured into this gap G to produce a half precast beam (not shown).

[0172] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0173] In addition, by forming a ring-shaped stirrup reinforcement 10G' by wrapping a portion of each reinforcement bar 10G together with the open portions 10a of both reinforcement bars 10G facing the other side, a half precast beam with high overall rigidity and integrity can be formed.

[0174] Furthermore, the upper end main reinforcement 30 at the lap position is surrounded by upper hooks 13A and 13B, both of which are 135-degree hooks, and similarly the lower end main reinforcement 40 at the lap position is surrounded by lower hooks 15A and 15B, both of which are 135-degree hooks, thereby improving the stress transferability between the reinforcing bars 10G of a pair of reinforced precast concrete slabs 50K.

[0175] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Figures 13 and 14. Here, Figure 13 is a perspective view of a precast concrete slab with reinforcing bars that is positioned first, constituting yet another example of a half precast beam according to the embodiment. Figures 14(a) to 14(d) are process diagrams, in that order, of the method for manufacturing yet another example of a half precast beam according to the embodiment.

[0176] The reinforced precast concrete slab 50L shown in Figure 13 differs from the reinforced precast concrete slab 50 in that, of the multiple reinforcing bars (nine in the illustrated example) attached to the precast concrete slab 20, the lengths t3, t2 of the lower hooks 15C, 15D of reinforcing bars 10H, 10I at both ends of the longitudinal direction are longer than the length t1 of the lower hooks 15 of the other seven reinforcing bars 10, making them longer lower hooks.

[0177] More specifically, of the reinforcing bars 10H, 10I, the length t3 of the long lower hook 15C of one of the reinforcing bars 10H is set longer than the length t2 of the long lower hook 15D of the other reinforcing bar 10I, and the relationship between the lengths t3, t2, and t1 of the long lower hook 15C (first long lower hook), long lower hook 15D (second long lower hook), and lower hook 15 is t3>t2>t1.

[0178] Here, the length t1 of the lower hook 15 of the reinforcing bar 10 and the length of the upper hook 13 may be the minimum required length.

[0179] As shown in Figure 14, in the production of a half precast beam, the precast concrete slab 50L shown in Figure 13 is positioned first, and the precast concrete slab 50 positioned afterwards has all the upper hooks 13 of the same length and all the lower hooks 15 of the same length, as explained above.

[0180] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 14(a), one of the reinforced precast concrete slabs 50L is positioned on the lower frame 91 with the open portion 10a of each reinforcing bar 10H facing the side of the reinforced precast concrete slab 50 that will be installed later, and the other reinforced precast concrete slab 50 is moved laterally in the X18 direction with the open portion 10a of each reinforcing bar 10 facing the side of the reinforced precast concrete slab 50L that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main bar 40 are passed between the upper hook 13 and long lower hook 15C of the left reinforced precast concrete slab 50L, and the upper hook 13 of the right reinforced precast concrete slab 50 is stopped from moving laterally when it passes through the one upper main bar 30 on the right side of the left reinforced precast concrete slab 50L.

[0181] Next, as shown in Figure 14(b), by lowering the right-side reinforced precast concrete slab 50 downward in the X19 direction, the first long lower hook 15C of the longest reinforcement 10H of the nine reinforcement bars 10, 10H, 10I provided in the reinforced precast concrete slab 50L is passed between the multiple lower horizontal bars 14 of the right-side reinforced precast concrete slab 50.

[0182] By further lowering the right-side reinforced precast concrete slab 50 downward in the X19 direction, the second long lower hook 15D of the next longest reinforcing bar 10I will be passed between the multiple lower cross bars 14 of the right-side reinforced precast concrete slab 50.

[0183] In this way, by first focusing on passing the first long lower hook 15C between the multiple lower cross bars 14, and then focusing on passing the second long lower hook 15D between the multiple lower cross bars 14, when the long lower hooks 15C, 15D of the reinforcing bars 10H, 10I at both ends of the nine reinforcing bars 10, 10H, 10I have passed between the corresponding multiple lower cross bars 14, the left and right reinforced precast concrete slabs 50L, 50 can be positioned parallel to each other.

[0184] Therefore, as shown in Figure 14(c), the right-side reinforcing bar precast concrete slab 50 can be smoothly lowered downward in the X20 direction, and as shown in Figure 14(d), by completely lowering the right-side reinforcing bar precast concrete slab 50 and placing it on the lower frame 91, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other to form ring-shaped (rectangular frame-shaped in the illustrated example) stirrup reinforcements 10H', and the upper horizontal reinforcements 12 overlap each other at equal intervals or In the illustrated example, multiple (seven in the illustrated example) upper end main reinforcements 30 are arranged at approximately equal intervals, with the central upper end main reinforcement 30 surrounded by left and right upper hooks 13, 13, and similarly, multiple (seven in the illustrated example) lower end main reinforcements 40 are arranged at equal or approximately equal intervals laterally relative to the overlapping lower transverse reinforcements 14, with the central lower end main reinforcement 40 surrounded by left and right lower hooks 15, 15C (15, 15D), so that reinforcement is automatically arranged and a gap G is formed between the pair of reinforcing bar precast concrete slabs 50L, 50. By pouring concrete into this gap G, a half precast beam (not shown) is produced.

[0185] Even with the manufacturing method shown in the illustration, a pair of reinforced precast concrete slabs 50L, 50 are formed by wrapping portions of both reinforcing bars 10H, 10 together with the open portions 10a facing the other side to form a ring-shaped stirrup bar 10H', thereby forming a half precast beam with high overall rigidity and integrity.

[0186] Here, as in the illustrated example, among the multiple reinforcing bars provided on the left-hand reinforced precast concrete slab, which is positioned first, the reinforcing bars at both ends may have long bottom hooks, or the bottom hooks of any one of all the reinforcing bars may be long bottom hooks, or, for example, the bottom hooks of three or more reinforcing bars may be long bottom hooks, and all of the long bottom hooks may be of different lengths (neither is shown).

[0187] Furthermore, although not shown in the figures, this may be a manufacturing method in which at least one or more of the upper hooks of the multiple reinforcing bars of the right-side reinforced precast concrete slab, which is positioned later, are long upper hooks that are longer than the length of all of the lower hooks of the reinforcing bars of the left-side reinforced precast concrete slab, which is positioned first, and when the right-side reinforced precast concrete slab is lowered, the long upper hooks are passed first between the multiple upper horizontal bars of the left-side reinforced precast concrete slab, and then the left and right reinforced precast concrete slabs are positioned so that both upper horizontal bars are overlapped and both lower horizontal bars are overlapped.

[0188] Even in this form, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the upper hook of one reinforcing bar is the longest, the first long upper hook, and the upper hook of the other reinforcing bar is the next longest, the second long upper hook.The first long upper hook is first passed between the multiple upper horizontal bars of the reinforced precast concrete slab on the right side, and then the second long upper hook is passed between the multiple upper horizontal bars of the reinforced precast concrete slab on the right side.This allows the reinforced precast concrete slabs on the left and right to be positioned parallel to each other, and the right side reinforced precast concrete slab can be smoothly lowered to position both.

[0189] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 15. Here, Fig. 15(a) to (e) are, in that order, process diagrams of the method for manufacturing another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of the other example of a half precast beam according to the embodiment.

[0190] A pair of reinforced precast concrete slabs 50M applicable to the manufacturing method shown in Figure 15 differs from the reinforced precast concrete slabs 50 comprising the precast concrete slab 20 in that the vertically extending vertical slabs 22 of the precast concrete slab 20D have upper recesses 28 and lower recesses 29 on the inside of their upper and lower ends, respectively, and the upper end main reinforcements 30 adjacent to the upper recesses 28 are spaced apart horizontally, and the lower end main reinforcements 40 adjacent to the lower recesses 29 are spaced apart horizontally.

[0191] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 15(a), one of the reinforced precast concrete slabs 50M is positioned on the lower frame 91 in an orientation in which the open portion 10a of each reinforcing bar 10H faces the side of the reinforced precast concrete slab 50M that will be installed later.

[0192] Next, as shown in Figure 15(b), the other reinforced concrete slab 50M is moved laterally in the X21 direction with the open portion 10a of each reinforcing bar 10 facing the side of the reinforced concrete slab 50M where the first reinforcement will be installed, and its lower cross bar 14, lower hook 15A and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the left reinforced precast concrete slab 50M, and the upper hook 13 of the right reinforced precast concrete slab 50M is stopped from moving laterally at a position where it has passed through one upper main reinforcement 30 on the right side of the left reinforced precast concrete slab 50M.

[0193] Next, as shown in Figure 15(c), the right-side reinforced precast concrete slab 50M is lowered downward in the X22 direction, moving the upper hook 13 downward so as to straddle one upper main reinforcement 30 at the lap position.

[0194] As shown in Figure 15(d), by completely lowering the right-side reinforced precast concrete slab 50M and placing it on the lower frame 91, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup reinforcement 10', and multiple (seven in the illustrated example) upper main reinforcements 30 are arranged at equal or approximately equal intervals in the horizontal direction for both overlapping upper horizontal reinforcements 12, and the central upper main reinforcement 30 is surrounded by left and right upper hooks 13. Similarly, multiple (seven in the illustrated example) lower main reinforcements 40 are arranged at equal or approximately equal intervals in the horizontal direction for both overlapping lower horizontal reinforcements 14, and the central lower main reinforcement 40 is surrounded by left and right lower hooks 15, so that the reinforcement is automatically arranged and a gap G is formed between the pair of reinforced precast concrete slabs 50M.

[0195] Next, as shown in Figure 15(e), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100G having a pair of reinforced precast concrete slabs 50M and a post-cast concrete body 60.

[0196] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0197] Furthermore, by forming a ring-shaped stirrup bar 10' by wrapping a portion of a pair of reinforced precast concrete slabs 50M together with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100G with high overall rigidity and integrity can be formed.

[0198] Furthermore, the vertical slabs 22 of the precast concrete slab 20D have upper and lower recesses 28 and 29 on the inside of their upper and lower ends, respectively, and the upper end main reinforcements 30 and lower end main reinforcements 40 adjacent to the upper and lower recesses 28 and 29 are spaced apart laterally, so that concrete can be sufficiently wrapped around the upper end main reinforcements 30 and lower end main reinforcements 40 adjacent to the vertical slab 22 when forming the post-cast concrete body 60, and the upper end main reinforcements 30 and lower end main reinforcements 40 arranged at the ends can be embedded without gaps inside the post-cast concrete body 60. Here, the vertical slabs 22 of the precast concrete slab 20D in the illustrated example have both the upper recess 28 and the lower recess 29, but the vertical slab 22 may have either the upper recess 28 or the lower recess 29.

[0199] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Figures 16 and 17. Here, Figure 16 is a perspective view of a pair of reinforcing steel precast concrete slabs that constitute yet another example of a half precast beam according to the embodiment. Also, Figures 17(a) to 17(e) are, in that order, process diagrams of a method for manufacturing yet another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of the yet another example of a half precast beam according to the embodiment.

[0200] As shown in Figure 16, a pair of second reinforced precast concrete slabs 50N differ from reinforced precast concrete slabs 50 in that the separate vertical reinforcements 11J forming the multiple separate U-shaped reinforcements 10J are embedded at intervals along the longitudinal direction of the precast concrete slab 20, and the upper horizontal reinforcements 12 and lower horizontal reinforcements 14 of the multiple C-shaped reinforcements 10 are respectively arranged in an overlapping manner with the separate upper horizontal reinforcements 12J and separate lower horizontal reinforcements 14J forming each separate reinforcement 10J, and are tied together, etc.

[0201] The separate reinforcing bar 10J is formed by a series of separate vertical bars 11J, separate upper horizontal bars 12J that bend at the upper end of the separate vertical bars 11J and extend horizontally, and separate lower horizontal bars 14J that bend at the lower end of the separate vertical bars 11J and extend horizontally, forming a U-shape.

[0202] In the vertical slab 22 of the precast concrete slab 20, the separate vertical reinforcing bars 11J of the plurality of separate reinforcing bars 10J are embedded at intervals in the longitudinal direction, and the separate upper horizontal reinforcing bars 12J and separate lower horizontal reinforcing bars 14J of each separate reinforcing bar 10J are respectively arranged in an overlapping manner with the separate upper horizontal reinforcing bars 12 and the separate lower horizontal reinforcing bars 14 of the corresponding reinforcing bars 10 and are then tied or welded. A plurality of upper end main reinforcing bars 30 extending in the longitudinal direction are attached below the plurality of upper horizontal reinforcing bars 12, and a plurality of lower end main reinforcing bars 40 extending in the longitudinal direction are attached above the plurality of lower horizontal reinforcing bars 14, thereby forming a second reinforcing bar-equipped precast concrete slab 50N.

[0203] Here, the entire precast concrete slab 50N with second steel reinforcement shown in the figure may be manufactured in a factory or the like, transported to the site and installed at the installation location, or the precast concrete slab 20, reinforcing bars 10, upper main reinforcement 30 and lower main reinforcement 40 may be transported to the site without the reinforcing bars 10, upper main reinforcement 30 and lower main reinforcement 40 attached (everything other than the reinforcing bars 10, upper main reinforcement 30 and lower main reinforcement 40 may be manufactured in a factory or the like), and after the precast concrete slab 20 is installed at the installation location on site, reinforcing bars 10 are attached to separate reinforcing bars 10J, and the upper main reinforcement 30 and lower main reinforcement 40 are attached to reinforcing bars 10 to form the precast concrete slab 50N with second steel reinforcement.

[0204] Furthermore, the precast concrete slab 20 and the upper main reinforcement 30 and the lower main reinforcement 40 may be transported to the site without the upper main reinforcement 30 and the lower main reinforcement 40 being attached (all reinforcement other than the upper main reinforcement 30 and the lower main reinforcement 40 may be manufactured in a factory, etc.), and after the precast concrete slab 20 is installed at the installation position on site, the upper main reinforcement 30 and the lower main reinforcement 40 may be attached to the reinforcing bar 10 to form the precast concrete slab 50N with second steel bars.

[0205] Although not shown in the drawings, a reinforcing bar 10 without a corresponding reinforcing bar 10J may be disposed between reinforcing bars 10 connected to separate reinforcing bars 10J. For example, in addition to reinforcing bars 10 connected to separate reinforcing bars 10J, reinforcing bars 10 not connected to separate reinforcing bars 10J may be disposed. In other words, any number of reinforcing bars 10 among the multiple reinforcing bars 10 constituting the reinforced precast concrete slab 50 shown in FIG. 1 may be provided instead of the reinforcing bars 10 connected to the separate reinforcing bars 10J of this embodiment. In this way, by combining reinforcing bars 10 of different embodiments, a number of reinforcing bars 10 sufficient to obtain the desired shear reinforcement effect can be disposed.

[0206] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 17(a), one of the second reinforced precast concrete slabs 50N is positioned on the lower frame 91 in an orientation in which the open portion 10a of each reinforcing bar 10 faces the side of the reinforced precast concrete slab 50N that will be installed later.

[0207] Next, as shown in Figure 17(b), the other second reinforced precast concrete slab 50N is moved laterally in the X23 direction with the open portion 10a of each reinforcing bar 10 facing the reinforced precast concrete slab 50N that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the left second reinforced precast concrete slab 50N, and the lateral movement of the upper hook 13 of the right second reinforced precast concrete slab 50N is stopped at the position where it has passed through the one upper main reinforcement 30 on the right side of the left second reinforced precast concrete slab 50N.

[0208] Next, as shown in Figure 17(c), the second reinforcing bar-equipped precast concrete slab 50N on the right side is lowered downward in the X24 direction, moving the upper hook 13 downward so as to straddle one upper end main reinforcement 30 at the lap position.

[0209] As shown in Figure 17(d), by completely lowering the right-side second steel-reinforced precast concrete slab 50N and placing it on the lower frame 91, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup reinforcement 10', and multiple (seven in the illustrated example) upper main reinforcements 30 are arranged at equal or approximately equal intervals in the horizontal direction for both upper horizontal reinforcements 12 that overlap each other, and the central upper main reinforcement 30 is surrounded by left and right upper hooks 13. Similarly, multiple (seven in the illustrated example) lower main reinforcements 40 are arranged at equal or approximately equal intervals in the horizontal direction for both lower horizontal reinforcements 14 that overlap each other, and the central lower main reinforcement 40 is surrounded by left and right lower hooks 15, so that the reinforcement is automatically arranged and a gap G is formed between the pair of second steel-reinforced precast concrete slabs 50N.

[0210] Next, as shown in Figure 17(e), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100H having a pair of second reinforcing bar-equipped precast concrete slabs 50N and a post-cast concrete body 60.

[0211] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0212] Furthermore, by forming a ring-shaped stirrup bar 10' by wrapping a portion of a pair of reinforced precast concrete slabs 50N together with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100H with high overall rigidity and integrity can be formed.

[0213] Furthermore, in contrast to the separate U-shaped reinforcing bars 10J in which separate vertical bars 11J are embedded in the precast concrete slab 20, the entire C-shaped reinforcing bars 10, which are tied together or the like, are embedded in the post-cast concrete body 60, thereby further enhancing the shear reinforcement effect of the reinforcing bars 10. As a result, even if the degree of integration between the precast concrete slab 20 and the post-cast concrete body 60 is not good, the C-shaped reinforcing bars 10 will provide a high shear reinforcement effect.

[0214] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 18. Here, Fig. 18(a) to (e) are, in that order, process diagrams of the method for manufacturing another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of the other example of a half precast beam according to the embodiment.

[0215] A pair of second reinforced precast concrete slabs 50P applied to the manufacturing method shown in Figure 18 differs from the second reinforced precast concrete slabs 50N in that wavy reinforcement bars 19 (truss bars) that extend vertically and have a wavy shape are connected to the separate vertical bars 11J of the separate reinforcement bars 10J and the vertical bars 11 of the reinforcement bars 10.

[0216] The crests and valleys of the wavy reinforcement bars 19 are welded to the separate vertical bars 11J and the vertical bars 11, thereby joining these three members together.

[0217] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 18(a), one of the second reinforcing bar precast concrete slabs 50P is positioned on the lower frame 91 in an orientation in which the open portion 10a of each reinforcing bar 10 faces the side of the reinforcing bar precast concrete slab 50P that will be installed later.

[0218] Next, as shown in Figure 18(b), the other second reinforced precast concrete slab 50P is moved laterally in the X25 direction with the open portion 10a of each reinforcing bar 10 facing the side of the reinforced precast concrete slab 50P that will be installed first, and its lower cross bar 14, lower hook 15 and one lower main reinforcement 40 are passed between the upper hook 13 and lower hook 15 of the left second reinforced precast concrete slab 50P, and the lateral movement of the upper hook 13 of the right second reinforced precast concrete slab 50P is stopped at the position where it has passed through the one upper main reinforcement 30 on the right side of the left second reinforced precast concrete slab 50P.

[0219] Next, as shown in Figure 18(c), the second reinforcing bar-equipped precast concrete slab 50P on the right side is lowered downward in the X26 direction, thereby moving the upper hook 13 downward so as to straddle one upper end main reinforcement 30 at the lap position.

[0220] As shown in Figure 18(d), by completely lowering the right-side second reinforcing bar-equipped precast concrete slab 50P and placing it on the lower frame 91, both upper horizontal bars 12 overlap each other, and both lower horizontal bars 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup bar 10', and multiple (seven in the illustrated example) upper main bars 30 are arranged at equal or approximately equal intervals in the horizontal direction for both overlapping upper horizontal bars 12, and the central upper main bar 30 is surrounded by left and right upper hooks 13. Similarly, multiple (seven in the illustrated example) lower main bars 40 are arranged at equal or approximately equal intervals in the horizontal direction for both overlapping lower horizontal bars 14, and the central lower main bar 40 is surrounded by left and right lower hooks 15, so that the reinforcement is automatically arranged and a gap G is formed between the pair of second reinforcing bar-equipped precast concrete slabs 50P.

[0221] Next, as shown in Figure 18(e), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100I having a pair of second reinforcing bar-equipped precast concrete slabs 50P and a post-cast concrete body 60.

[0222] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0223] Furthermore, by forming a ring-shaped stirrup bar 10' by overlapping a portion of a pair of reinforced precast concrete slabs 50P with the open portions 10a of both reinforcing bars 10 facing the other side, a half precast beam 100I with high overall rigidity and integrity can be formed.

[0224] Furthermore, by connecting the vertical reinforcement 11 of the C-shaped reinforcement 10 and the separate vertical reinforcement 11J of the U-shaped separate reinforcement 10J with wavy reinforcement 19 that extends vertically and has a wavy shape, it is possible to achieve a stronger integration of the two. Also, with this configuration, the vertical reinforcement 11, the separate vertical reinforcement 11J, and the wavy reinforcement 19 between them can resist, in a similar manner to a truss beam, pressure acting on the inside of the precast concrete slab 20 when concrete is poured in the construction of the post-cast concrete body 60, and earth pressure acting on the outside of the precast concrete slab 20 when soil is backfilled before concrete is poured.

[0225] 1 to 18, half precast beams applied to beams on the upper floors of a building and their manufacturing methods have been described above, but as shown in Fig. 19, half precast beams may also be applied to foundation beams of a building. Here, Figs. 19(a) and 19(b) are both longitudinal cross-sectional views perpendicular to the longitudinal direction of a pair of reinforcing steel precast concrete slabs assembled together, which constitute yet another example of a half precast beam according to an embodiment, and both show an example in which a pair of reinforcing steel precast concrete slabs 50G described with reference to Fig. 9 is applied to a foundation beam.

[0226] In the example shown in Figure 19(a), leveling materials (such as crushed stone 95 and basal concrete 96) are laid on a floor surface created by excavating the ground to ensure levelness, and a pair of reinforcing steel precast concrete slabs 50G are placed on top of the basal concrete 96, forming a gap G between them. Concrete is poured into the gap G to produce a foundation beam, which is a half-precast beam (not shown).

[0227] On the other hand, the example shown in Figure 19(b) involves placing a precast concrete slab 20E that also serves as a lower frame on top of crushed stone 95, and fitting the lower ends of a pair of reinforced precast concrete slabs 50G into a pair of recesses 25 provided on the upper surface of the precast concrete slab 20E that also serves as a lower frame.

[0228] The lower end of the reinforcing steel precast concrete slab 50G is fitted into the recess 25 of the precast concrete slab 20E which also serves as the lower frame, so that the stable upright position of the reinforcing steel precast concrete slab 50G can be maintained while eliminating the need for leveling materials.

[0229] Next, a method for manufacturing yet another example of a half precast beam according to an embodiment will be described with reference to Figures 20 and 21. Here, Figure 20 is a perspective view of a pair of reinforcing steel precast concrete slabs that constitute yet another example of a half precast beam according to an embodiment. Figures 21(a) to 21(c) are, in that order, process diagrams of a method for manufacturing yet another example of a half precast beam according to an embodiment, and are also diagrams showing vertical cross-sectional views perpendicular to the longitudinal direction of the yet another example of a half precast beam according to an embodiment.

[0230] The pair of reinforced precast concrete slabs 50Q shown in Figures 20 and 21 differ from the reinforced precast concrete slab 50 having reinforcement bars 10 with upper hooks 13 and lower hooks 15 in that neither reinforcement bar 10L has upper and lower hooks.

[0231] Since the reinforcing bar 10L does not have an upper hook or a lower hook, the open portion 10a is set relatively long in the vertical direction.

[0232] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 21(a), one reinforced concrete slab 50Q is positioned on the lower frame 91 with the open portion 10a of each reinforcing bar 10 facing the side of the reinforced concrete slab 50Q that will be installed later, and the other reinforced concrete slab 50Q is moved laterally in the X27 direction with the open portion 10a of each reinforcing bar 10 facing the side of the reinforced concrete slab 50Q that will be installed first.

[0233] Next, as shown in Figure 21(b), by lowering the right-side reinforced precast concrete slab 50Q downward in the X28 direction, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup reinforcement 10L', and multiple (seven in the illustrated example) upper main reinforcements 30 are arranged at equal or approximately equal intervals in the horizontal direction on both upper horizontal reinforcements 12 that overlap each other, and similarly, multiple (seven in the illustrated example) lower main reinforcements 40 are arranged at equal or approximately equal intervals in the horizontal direction on both lower horizontal reinforcements 14 that overlap each other, so that the reinforcement is automatically completed, and a gap G is formed between the pair of second reinforced precast concrete slabs 50Q.

[0234] Here, since neither reinforcing bar 10L has an upper hook or a lower hook, it is desirable to set the lap length between the upper horizontal bars 12 and the lap length between the lower horizontal bars 14 to a predetermined lap joint length, and it is preferable to lap the reinforcing bars 10L with a nominal diameter d of, for example, 40d.

[0235] Next, as shown in Figure 21(d), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100J having a pair of reinforced precast concrete slabs 50Q and a post-cast concrete body 60.

[0236] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0237] Furthermore, by forming a ring-shaped stirrup reinforcement 10L' by wrapping a portion of a pair of reinforced precast concrete slabs 50Q together with the open portions 10a of both reinforcing bars 10L facing the other side, a half precast beam 100J with high overall rigidity and integrity can be formed.

[0238] Next, a method for manufacturing yet another example of a half precast beam according to the embodiment will be described with reference to Fig. 22. Here, Fig. 22(a) to (c) are, in that order, process diagrams of the method for manufacturing another example of a half precast beam according to the embodiment, and are also diagrams showing longitudinal cross-sectional views perpendicular to the longitudinal direction of the other example of a half precast beam according to the embodiment.

[0239] One of the reinforced precast concrete slabs 50R shown in Figure 22 has all of the upper main reinforcements 30 (seven in the illustrated example) arranged on the upper hooks 12, and no lower main reinforcements 40 arranged on the lower hooks 14, while the other reinforced precast concrete slab 50S differs from the reinforced precast concrete slab 50Q in that no upper main reinforcements 30 are arranged on the upper hooks 12, and all of the lower main reinforcements 40 (seven in the illustrated example) are arranged on the lower hooks 14.

[0240] Regarding the manufacturing method of the illustrated example, first, as shown in Figure 22(a), one of the reinforced precast concrete slabs 50R is positioned on the lower frame 91 in an orientation in which the open portions 10a of each reinforcing bar 10 face toward the reinforced precast concrete slab 50S that will be installed later, and the other reinforced precast concrete slab 50S is moved laterally in the X29 direction in an orientation in which the open portions 10a of each reinforcing bar 10 face toward the reinforced precast concrete slab 50R that will be installed first.

[0241] Next, as shown in Figure 22(b), by lowering the right-side reinforced precast concrete slab 50S downward in the X30 direction, both upper horizontal reinforcements 12 overlap each other, and both lower horizontal reinforcements 14 overlap each other, forming a ring-shaped (in the illustrated example, rectangular frame-shaped) stirrup reinforcement 10L', and multiple (seven in the illustrated example) upper main reinforcements 30 are arranged at equal or approximately equal intervals in the horizontal direction on both upper horizontal reinforcements 12 that overlap each other, and similarly, multiple (seven in the illustrated example) lower main reinforcements 40 are arranged at equal or approximately equal intervals in the horizontal direction on both lower horizontal reinforcements 14 that overlap each other, so that the reinforcement is automatically arranged, and a gap G is formed between the pair of second reinforced precast concrete slabs 50R, 50S.

[0242] Here too, since neither reinforcing bar 10L has upper and lower hooks, it is desirable to set the lap length between the upper horizontal bars 12 and the lap length between the lower horizontal bars 14 to a predetermined lap joint length.

[0243] Next, as shown in Figure 22(d), concrete is poured into the gap G to form a post-cast concrete body 60, thereby producing a half precast beam 100K having a pair of reinforced precast concrete slabs 50R, 50S and a post-cast concrete body 60.

[0244] The manufacturing method shown in the illustration also eliminates or reduces the labor required for beam reinforcement arrangement while reducing the labor required for installing and removing formwork, resulting in a manufacturing method that is superior in beam manufacturability and can improve quality.

[0245] Furthermore, by forming a ring-shaped stirrup reinforcement 10L' by wrapping a portion of each reinforcement bar 10L together with the open portions 10a of both reinforcement bars 10L facing the other side, a half precast beam 100J with high overall rigidity and integrity can be formed.

[0246] The present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0247] 10, 10A, 10B, 10D, 10E, 10F, 10G, 10H, 10I, 10L: Reinforcement bars 10', 10A', 10B', 10D', 10E', 10F', 10G', 10H', 10I', 10L': Stirrup muscles 10C: Reinforcement bars (large diameter reinforcing bars) 10J: Separate reinforcement 10a: Open part 11: Vertical stripes 11J: Separate vertical reinforcement 12: Upper transverse muscle 12J: Separate upper horizontal muscle 13: Upper hook (90 degree hook) 13A, 13B: Upper hook (135 degree hook) 13a: The part that bends and extends in a 90-degree direction 14: Lower transverse muscle 14J: Separate lower transverse muscle 15: Bottom hook (90 degree hook) 15A, 15B: Lower hook (135 degree hook) 15C: Lower hook (first long lower hook, long lower hook) 15D: Lower hook (second long lower hook, long lower hook) 15a: The part that bends and extends in a 90-degree direction 16: Core muscle 17: Preparation muscle 18A, 18B: Accessory muscles 19: Wavy reinforcement bars 20, 20A, 20B, 20C, 20D: Precast concrete panels 20E: Precast concrete slab (also used as lower frame) 25: Recess 22:Vertical version 24: Upper horizontal version 26,27A,27B: Lower horizontal version 27a: Recess 28: Upper concave 29: Downward depression 30: Top main reinforcement 40: Bottom main reinforcement 50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I, 50J, 50K, 50L, 50M, 50Q, 50R, 50S: Reinforced precast concrete panel 50N, 50P: Precast concrete slab with secondary rebar 60: Post-cast concrete body 60A: Concrete deck 91: Bottom frame 92: Floor frame 93: Floor line 95: Crushed stone (land leveling material) 96: Disposable concrete (land leveling material) 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H, 100I, 100J, 100K: Half precast beams G: Gap

Claims

1. a pair of reinforced precast concrete slabs, each of which has a plurality of reinforcing bars embedded at intervals in the longitudinal direction of the precast concrete slabs, and each of which has an opening; A half precast beam characterized in that the pair of reinforced concrete slabs are arranged with a gap between them, with the open portions of both reinforcing bars facing the other side and parts of both reinforcing bars overlapping each other to form an annular stirrup bar, and a post-cast concrete body is provided in the gap.

2. 2. The half precast beam according to claim 1, wherein the plurality of reinforcing bars of both of the pair of reinforced precast concrete slabs have main bars attached thereto extending in the longitudinal direction.

3. 3. The half precast beam according to claim 1, wherein the overlapping portions of the reinforcing bars are not connected to each other.

4. 3. The half precast beam according to claim 1, wherein the overlapping portions of the reinforcing bars are connected to each other.

5. 3. The half precast beam according to claim 1, wherein the pair of reinforced precast concrete slabs have the same shape and configuration.

6. a pair of reinforced concrete slabs, each of which has a plurality of vertical reinforcing bars embedded at intervals in the longitudinal direction of the precast concrete slab, each of which has a vertical reinforcing bar, an upper horizontal reinforcing bar bent at the upper end of the vertical reinforcing bar and extending horizontally, an upper hook bent at the end of the upper horizontal reinforcing bar and extending downward, a lower horizontal reinforcing bar bent at the lower end of the vertical reinforcing bar and extending horizontally, and a lower hook bent at the end of the lower horizontal reinforcing bar and extending upward, forming a C-shape; A half precast beam characterized in that the pair of reinforced precast concrete slabs are arranged with a gap between them, with both upper horizontal reinforcements overlapping each other and both lower horizontal reinforcements overlapping each other, and a post-cast concrete body is provided in the gap.

7. Among the upper end main reinforcements attached to the upper cross bars of each of the pair of reinforced concrete slabs, the upper end main reinforcements arranged at the lap positions of both upper cross bars are attached only below one of the upper cross bars, and are not attached below the other upper cross bar, Among the lower end main reinforcements attached to the lower transverse reinforcements of each of the pair of reinforced concrete slabs, the lower end main reinforcements arranged at the lap positions of both the lower transverse reinforcements are attached only above one of the lower transverse reinforcements, and are not attached above the other lower transverse reinforcement, 7. The half precast beam according to claim 6, wherein, when the upper horizontal reinforcements are overlapped with each other and the lower horizontal reinforcements are overlapped with each other, the upper main reinforcements are aligned horizontally at equal or approximately equal intervals, and the lower main reinforcements are aligned horizontally at equal or approximately equal intervals.

8. the upper end main reinforcement is disposed between the corresponding upper hooks of the pair of reinforcing bar-equipped precast concrete slabs, and both upper hooks are engaged with the upper end main reinforcement; 8. The half precast beam according to claim 6 or 7, wherein the lower end main reinforcement is arranged between the corresponding lower hooks of the pair of reinforced precast concrete slabs, and both lower hooks are engaged with the lower end main reinforcement.

9. 8. The half precast beam according to claim 6 or 7, wherein some of the upper main reinforcements among the plurality of upper main reinforcements are embedded in the precast concrete slab, and some of the lower main reinforcements among the plurality of lower main reinforcements are embedded in the precast concrete slab.

10. 8. The half precast beam according to claim 6 or 7, characterized in that the precast concrete slab comprises a vertical slab extending in the vertical direction, and an upper horizontal slab and a lower horizontal slab extending horizontally from the upper end and lower end of the vertical slab, respectively, and some of the upper main reinforcements of the plurality of upper main reinforcements are embedded in the upper horizontal slab, and some of the lower main reinforcements of the plurality of lower main reinforcements are embedded in the lower horizontal slab.

11. The precast concrete slab comprises a vertical slab extending in the vertical direction and a lower horizontal slab extending in the horizontal direction from a lower end of the vertical slab, and a plurality of the lower end main reinforcements are embedded in the lower horizontal slab, A half precast beam as described in claim 6 or 7, characterized in that the end faces of the lower horizontal plates of each of the pair of reinforced precast concrete plates abut against each other, and some or all of the lower main bars of the multiple lower main bars are embedded in both of the lower horizontal plates.

12. The precast concrete slab comprises a vertical slab extending in a vertical direction; An upper recess and a lower recess are provided on the inside of the upper end and the lower end of the vertical plate, respectively; 8. The half precast beam according to claim 6 or 7, wherein the upper end main reinforcement adjacent to the upper depression is spaced apart in the horizontal direction, and the lower end main reinforcement adjacent to the lower depression is spaced apart in the horizontal direction.

13. The reinforcing bars comprise a plurality of reinforcing bars, each of which has a vertical reinforcing bar, an upper horizontal reinforcing bar that is bent at the top end of the vertical reinforcing bar and extends horizontally, an upper hook that is bent at the end of the upper horizontal reinforcing bar and extends downward, a lower horizontal reinforcing bar that is bent at the bottom end of the vertical reinforcing bar and extends horizontally, and a lower hook that is bent at the end of the lower horizontal reinforcing bar and extends upward, all of which are connected to form a C-shape, The structure is provided with a plurality of separate reinforcing bars, each of which includes a separate vertical bar, a separate upper horizontal bar that is bent at the upper end of the separate vertical bar and extends horizontally, and a separate lower horizontal bar that is bent at the lower end of the separate vertical bar and extends horizontally, and these bars are connected to form a U-shape. The separate longitudinal reinforcement of each of the plurality of separate reinforcing bars is embedded at intervals in the longitudinal direction of the precast concrete slab, The upper and lower cross bars of the corresponding reinforcing bars are respectively lapped and arranged and tied or welded to the separate upper and lower cross bars of the separate reinforcing bars, a pair of second reinforcing bars in which upper end main reinforcements extending in the longitudinal direction are attached below the plurality of upper horizontal reinforcements and lower end main reinforcements extending in the longitudinal direction are attached above the plurality of lower horizontal reinforcements; A half precast beam characterized in that the pair of precast concrete slabs with second reinforcing bars are arranged with a gap between them, with both upper horizontal bars overlapping each other and both lower horizontal bars overlapping each other, and a post-cast concrete body is provided in the gap.

14. A half-precast beam as described in claim 13, characterized in that in the longitudinal direction, between the reinforcing bars that are tied or welded to the separate reinforcing bars, there are reinforcing bars that do not have the other separate reinforcing bars present.

15. The half precast beam according to claim 13, wherein wavy reinforcement bars extending in the vertical direction and having a wavy shape are connected to the vertical reinforcement bars and the additional vertical reinforcement bars.

16. 8. The half precast beam according to claim 6 or 7, characterized in that a core bar is further provided inside the C-shaped reinforcing bar, which is engaged with the upper end main bar and the lower end main bar.

17. The upper end main reinforcement is provided in a plurality of stages, and each stage includes a plurality of the upper end main reinforcement, 8. The half precast beam according to claim 6 or 7, wherein the lower end main reinforcement is provided in a plurality of stages, and each stage includes a plurality of the lower end main reinforcement.

18. Auxiliary reinforcement to prevent sagging or shaking of the upper horizontal reinforcement to which the upper end main reinforcement is attached is arranged so as to straddle the upper horizontal reinforcement or the upper hook and the vertical reinforcement, The half precast beam according to claim 17, characterized in that auxiliary reinforcement for preventing sagging or swaying of the lower horizontal reinforcement to which the lower end main reinforcement is attached is arranged so as to straddle the lower horizontal reinforcement or the lower hook and the vertical reinforcement.

19. A half-precast beam as described in claim 17, characterized in that among the multiple reinforcing bars aligned in the longitudinal direction, some of the reinforcing bars have relatively large cross-sectional diameters, and these large diameter reinforcing bars prevent sagging or swaying of both the upper horizontal bars and the lower horizontal bars.

20. One of the upper hooks of each of the pair of reinforcing steel precast concrete slabs is a 90-degree hook or a 135-degree hook, and the other is a 135-degree hook; 8. A half precast beam as described in claim 6 or 7, characterized in that one of the lower hooks of each of the pair of reinforced precast concrete slabs is a 90-degree hook or a 135-degree hook, and the other is a 135-degree hook.

21. A pair of reinforced precast concrete slabs is provided, each of which has a plurality of reinforcing bars embedded at intervals in the longitudinal direction of the precast concrete slab, and each of the reinforcing bars has an opening; One of the reinforcing bars is positioned with the open portion of the reinforcing bar facing the other side, and the other reinforcing bar is moved with the open portion of the reinforcing bar facing the other side, and portions of both reinforcing bars are overlapped to form annular stirrup bars and positioned with a gap between them; A method for manufacturing a half precast beam, characterized in that concrete is poured into the gap to form a post-cast concrete body, thereby manufacturing a half precast beam.

22. 22. The method for manufacturing a half precast beam as described in claim 21, characterized in that, at the stage when the pair of reinforced precast concrete slabs are prepared, main reinforcements extending in the longitudinal direction are attached to the plurality of reinforcing bars of both slabs.

23. A pair of reinforced concrete slabs is prepared, in which a plurality of reinforcing bars are embedded in the longitudinal direction of the precast concrete slab at intervals, each of which has a C-shape consisting of vertical bars, upper horizontal bars that bend at the upper ends of the vertical bars and extend horizontally, upper hooks that bend at the ends of the upper horizontal bars and extend downward, lower horizontal bars that bend at the lower ends of the vertical bars and extend horizontally, and lower hooks that bend at the ends of the lower horizontal bars and extend upward, and upper main bars that extend longitudinally are attached below the plurality of upper horizontal bars, and lower main bars that extend longitudinally are attached above the plurality of lower horizontal bars, One of the reinforcing steel precast concrete slabs is positioned, and the other reinforcing steel precast concrete slab is moved laterally to pass its lower cross bars, lower hooks, and lower end main bars between the upper hooks and lower hooks of one of the reinforcing steel precast concrete slabs.The other reinforcing steel precast concrete slab is then lowered downward to overlap the upper cross bars of both slabs and to overlap the lower cross bars of both slabs, while positioning the other reinforcing steel precast concrete slab with a gap between it and the one of the reinforcing steel precast concrete slabs. A method for manufacturing a half precast beam, characterized in that concrete is poured into the gap to form a post-cast concrete body, thereby manufacturing a half precast beam.

24. Among the upper end main reinforcements attached to the upper horizontal reinforcements of each of the pair of reinforced concrete slabs, the upper end main reinforcements arranged at the lap positions of both upper horizontal reinforcements are attached only below one of the upper horizontal reinforcements, and are not attached below the other upper horizontal reinforcement, Among the lower end main reinforcements attached to the lower transverse reinforcements of each of the pair of reinforced concrete slabs, the lower end main reinforcements arranged at the lap positions of both the lower transverse reinforcements are attached only above one of the lower transverse reinforcements, and are not attached above the other lower transverse reinforcement, 24. The method for manufacturing a half precast beam according to claim 23, characterized in that the upper transverse reinforcements are overlapped with each other and the lower transverse reinforcements are overlapped with each other, thereby arranging the upper main reinforcements in the horizontal direction at equal or approximately equal intervals and arranging the lower main reinforcements in the horizontal direction at equal or approximately equal intervals.

25. The precast concrete slab comprises a vertical slab extending in the vertical direction and a lower horizontal slab extending in the horizontal direction from a lower end of the vertical slab, and a plurality of the lower end main reinforcements are embedded in the lower horizontal slab, By abutting the end faces of the lower horizontal plates of the pair of reinforcing steel precast concrete slabs, both vertical plates and both lower horizontal plates form a U-shaped formwork with a cross-sectional shape perpendicular to the longitudinal direction that opens upward, 25. The method for manufacturing a half precast beam according to claim 23 or 24, characterized in that concrete is poured into the formwork to form the post-cast concrete body.

26. At least one of the lower hooks of the plurality of reinforcing bars provided in one of the reinforcing bar precast concrete slabs that is positioned first is a long lower hook that is longer than the length of the upper hooks of all of the reinforcing bars provided in the other reinforcing bar precast concrete slab that is positioned later, When lowering the other reinforcing bar precast concrete slab downward, the long lower hook is passed through the lower cross bars of the other reinforcing bar precast concrete slab in advance, and then both upper cross bars are overlapped and both lower cross bars are overlapped, or At least one of the upper hooks of the plurality of reinforcing bars provided on the other reinforcing bar precast concrete slab to be positioned subsequently is a long upper hook that is longer than the length of the lower hooks of all of the reinforcing bars provided on the one reinforcing bar precast concrete slab to be positioned first, A method for manufacturing a half precast beam as described in claim 23, characterized in that when lowering the other reinforced concrete slab downward, the long upper hook is first passed between the multiple upper cross bars of one of the reinforced concrete slabs, and then the upper cross bars of both slabs are overlapped and the lower cross bars of both slabs are overlapped.

27. In the embodiment having the long bottom hook, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the bottom hook of one of the reinforcing bars is the longest first long bottom hook, and the bottom hook of the other reinforcing bar is the next longest second long bottom hook, The first long lower hook is passed through between the plurality of lower horizontal bars of the other reinforcing bar-equipped precast concrete slab, and then the second long lower hook is passed through between the plurality of lower horizontal bars of the other reinforcing bar-equipped precast concrete slab, or In the embodiment having the long upper hook, of the two reinforcing bars located at both ends of the longitudinal direction of the precast concrete slab, the upper hook of one of the reinforcing bars is the longest first long upper hook, and the upper hook of the other reinforcing bar is the next longest second long upper hook, A method for manufacturing a half precast beam as described in claim 26, characterized in that the first long upper hook is first passed between the multiple upper cross bars of one of the reinforced precast concrete slabs, and then the second long upper hook is passed between the multiple upper cross bars of one of the reinforced precast concrete slabs.

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