JP7822006B2 - Method for constructing slab-like members - Google Patents

Description

The present invention relates to a construction method for constructing slab-like members made of half-precast concrete.

In composite concrete structures containing reinforcing bars, such as reinforced concrete structures, slab-like members made of half-precast concrete, which combine precast members and cast-in-place concrete members, are used to reduce labor and manpower on site. For example, two concrete members (a precast concrete member and a cast-in-place concrete member) are combined to produce members that make up various structures, such as the top slab, beam members, and column members of a structure.

For example, Patent Document 1 discloses precast concrete slabs and the floor slab structure of a building equipped with them. According to the invention disclosed in Patent Document 1, by using a steel frame with vertical ribs as the upper end member that makes up the truss structure reinforcement, it is possible to reduce costs, shorten construction time, and improve on-site workability.

Japanese Patent Application Laid-Open No. 2000-1938

However, the technology described in Patent Document 1 uses a steel frame with vertical ribs as the top member, and because this top member needs to be strong, there are concerns that the member will become larger and heavier. Therefore, there is room for further improvement in terms of workability and cost. Reinforcing bar work for cast-in-place sections is done on-site, and workability is poor, especially when the reinforcing bars are densely arranged. Therefore, there is a need to improve workability and shorten the construction period for reinforcing bar work by, for example, unitizing the reinforcing bars. The inventors have conducted extensive research into technologies that can further improve workability and shorten construction periods for methods of constructing slab-like members made of half-precast concrete.

In light of the above circumstances, the object of the present invention is to provide a method for constructing slab-like members made of half-precast concrete that can improve workability and shorten construction time.

In order to achieve the above object, according to the present invention, there is provided a method for constructing a half -precast concrete slab-like member that is made of a precast slab and cast-in-place concrete, and that is installed by bridging a pair of support members that extend in the vertical direction and have shoulders and a top extending upward from the shoulders, the method comprising the steps of placing the widthwise ends of the precast slab on the shoulders of the pair of support members, placing the ends on the tops of the pair of support members and bridging supports above the precast slab, and attaching hanging members that extend downward from the supports bridging above the precast slab. a step of suspending the precast slab through a cast-in-place concrete support; a step of constructing a reinforcing bar structure above the precast slab; a step of pouring and curing cast-in-place concrete onto the top of the precast slab and the shoulder portion so that the top surface of the cast-in-place concrete is aligned with the upper end of the crest so as to embed at least a portion of the hanging material and the reinforcing bar structure; and a step of separating the hanging material from the shoring and removing the shoring, wherein the hanging material embedded in the cast-in-place concrete in the slab-like member functions as shear reinforcement.

The precast slab may be reinforced by a reinforcing material embedded in the precast slab, and in the process of suspending the precast slab, the lower end of the suspending material may be connected to the reinforcing material or the precast slab.

A male thread is machined on the upper end of the hanging material, and in the process of hanging the precast slab, the hanging material can be raised and lowered by tightening or loosening a nut that threads onto the male thread at the connection between the support and the hanging material, thereby adjusting the posture of the precast slab.

The hanging member has a structure in which an upper hanging member connected to the support and a lower hanging member connected to the precast slab are connected by joints,
In the step of removing the support, the lower hanging member may be separated from the support by removing the joint.

The lower hanging member may have fixings at its upper and lower ends.

The support member may be a culvert wall, and the slab-like member may be the top plate of the culvert.

The support member may be a column and the slab-like member may be a beam.

The reinforcing steel structure includes main reinforcing steel bars installed parallel to the width of the precast slab and distribution steel bars installed in a direction intersecting the main reinforcing steel bars, and the hanging member may be anchored to one or both of the main reinforcing steel bars and the distribution steel bars.

The precast slabs are installed adjacent to each other along the length of the culvert , and distribution bars extending along the length of the culvert are embedded in the precast slabs so that their ends protrude from the precast slab. Adjacent precast slabs are connected to each other by joints between the distribution bars, and in the process of pouring and curing the cast-in-place concrete, concrete may be poured between adjacent precast slabs as well.

This invention makes it possible to improve workability and shorten construction time when constructing slab-like members made of half-precast concrete.

The above effects are not necessarily limiting, and any of the effects described in this specification, or other effects that can be understood from this specification, may be achieved in addition to or instead of the above effects.

FIG. 2 is a schematic plan view of the top plate structure. FIG. 2 is a schematic side cross-sectional view of the top plate structure. FIG. 2 is a schematic explanatory diagram showing an example of the configuration of a hanging material. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 10 is a process diagram for constructing a top plate structure. FIG. 1 is a schematic explanatory diagram showing an example of the configuration of a precast slab. FIG. 1 is a schematic explanatory diagram of the connection between a precast slab and a hanging member. This is a schematic cross-sectional view of a case where channel steel is used as support. This is a process diagram for constructing a beam. This is a process diagram for constructing a beam. This is a process diagram for constructing a beam. This is a process diagram for constructing a beam. This is a process diagram for constructing a beam. This is a process diagram for constructing a beam. This is a process diagram for constructing a beam. This is a schematic diagram of the installation of support via a platform between the support and the top. FIG. 10 is a schematic explanatory diagram showing another example of the configuration of the hanging material.

Embodiments of the present invention will be described below with reference to the drawings. In this specification and drawings, components having substantially the same functional configuration will be assigned the same reference numerals, and redundant description will be omitted. Note that this embodiment will be described by exemplifying the construction of a culvert top plate using the method for constructing a slab-like member according to the present invention. Furthermore, in the embodiments of this specification, for the purpose of explanation, some of the reinforcing bar structure and reinforcing bar arrangement may be omitted from illustration, or reinforcing bars inside the member may be illustrated.

In the following description, the direction in which the internal space of a culvert extends is referred to as the "length direction" of the culvert, the direction perpendicular to the length direction so as to cut across the internal space is referred to as the "width direction" of the culvert, and the direction perpendicular to these length and width directions is referred to as the "height direction." In the drawings, the length direction may be illustrated as the "Y axis," the width direction as the "X axis," and the height direction as the "Z axis." Furthermore, the width direction of the precast slab 20 described below refers to the same direction as the width direction of the culvert described above.

<Top plate structure configuration>
1 and 2 are schematic explanatory diagrams of a top plate structure 1 constructed by a method for constructing a slab-like member according to an embodiment of the present invention, with Fig. 1 showing a schematic plan view and Fig. 2 showing a schematic side cross-sectional view. This top plate structure 1 is an example of a slab-like member that is mounted across multiple support members, such as the side walls of a culvert. For the sake of explanation, Fig. 2 also shows, in addition to the top plate structure 1, support members (support members 10, described below) and shoring (shoring 30, described below) including hanging members that may eventually be removed.

As shown in Figures 1 and 2, the top plate structure 1 is mounted across a pair of support members 10 (10a, 10b), such as the side walls or middle walls of a culvert. The support member 10 includes a shoulder 12 on its upper surface for mounting a precast slab 20 (described below), and a top portion 14 extending upward from the shoulder 12. The top plate structure 1 includes multiple precast slabs 20 mounted on the shoulders 12, 12 with their widthwise (X-direction in the figure) ends facing each other, straddling the pair of support members 10. In the configuration of this embodiment, the multiple precast slabs 20 are mounted adjacent to each other along the length of the culvert (Y-direction in the figure).

The precast slab 20 may be a component (a so-called precast component) prefabricated in a factory or the like, or may be reinforced by including reinforcing material 27. The reinforcing material 27 is not particularly limited, but may be, for example, steel such as H-section steel or PC steel, or reinforcing bars.

Above the precast slab 20, shoring 30 is installed so as to span the opposing tops 14, 14 of the support members 10. The shoring 30 may be, for example, H-shaped steel. A number of hanging members 33 extending downward are connected to the shoring 30. Various steel materials may be used as the hanging members 33, such as deformed steel bars, separators, PC steel, and fully threaded bolts.

The means of connecting the shoring 30 and the hanging material 33 is optional. For example, the shoring 30 may be drilled, a male thread may be drilled into the upper end of the hanging material 33, and the connection between the shoring 30 and the hanging material 33 may be achieved by threading the male thread and tightening a nut.

Figure 3 is a schematic diagram showing an example of the configuration of the hanging member 33, and is an enlarged view of the dashed line portion in Figure 2. As an example, as shown in Figure 3, the hanging member 33 may be composed of an upper hanging member 33a connected to the shoring 30 and a lower hanging member 33b connected to the precast slab 20. A fixing device 34 may be provided at the upper end of the lower hanging member 33b. A similar fixing device (not shown in Figure 3) may also be provided at the lower end of the lower hanging member 33b. As shown in Figure 3, the upper hanging member 33a and the lower hanging member 33b may be connected by a joint 35 including a nut 35a and a P cone 35b.

When the precast slab 20 is suspended by the support 30, the lower end of the suspension member 33 is connected to the precast slab 20 or the reinforcing member 27. The means of connection is optional; for example, the reinforcing member 27 may be drilled and a nut (not shown) may be threaded through the drilled hole to engage with a male thread.

A reinforcing steel structure 40 is constructed above the precast slab 20. This reinforcing steel structure 40 includes multiple main reinforcing steel bars 44 installed parallel to the width of the precast slab 20, and multiple distribution reinforcement bars 42 installed in a direction intersecting (e.g., perpendicular to) the main reinforcing steel bars 44. At least a portion of the hanging member 33 may be anchored to one or both of the main reinforcing steel bars 44 and the distribution reinforcement bars 42. Note that this reinforcing steel structure 40 may be fabricated off-site in advance. "Off-site" refers to a location different from the installation site, and is a concept that excludes the installation site itself. In other words, the phrase "fabricated off-site" includes cases where the structure is fabricated in a factory or near the installation site, for example.

Above the precast slab 20, a cast-in-place concrete section 50 is constructed, in which concrete is poured to embed at least a portion of the hanging member 33 and the reinforcing steel structure 40. As shown in Figure 2, when constructing the cast-in-place concrete section 50, at least a portion of the hanging member 33 and the reinforcing steel structure 40 are buried inside, and concrete is also poured on the top of the shoulder section 12. For example, concrete may be poured so that the top surface is aligned with the top end of the peak 14 in the height direction.

The top slab structure 1 is constructed as described above with reference to Figures 1 to 3. During the construction process of the top slab structure 1, the shoring 30 shown in Figure 2 is used to suspend the precast slab 20. However, once the top slab structure 1 is finally constructed, the shoring 30 is removed. The shoring 30 may be removed, for example, by releasing the connection between the upper hanging member 33a and the lower hanging member 33b via the joint 35.

<How to construct the top plate structure>
Next, we will explain the method for constructing the top plate structure 1 described above. Figures 4 to 10 are process diagrams for constructing the top plate structure 1 using the method for constructing a slab-like member according to an embodiment of the present invention, and the processes are carried out in the order shown in Figures 4 to 10. For the purpose of explanation, each of Figures 4 to 10 shows a schematic plan view in (a), a schematic side cross-sectional view in (b), and an A-A cross-sectional view in (c), and Figures 5 to 10 also show a B-B cross-sectional view in (d).

First, as shown in Figure 4, a pair of support members 10 (10a, 10b), which serve as the side walls of a culvert, are constructed. The support members 10 are constructed to include shoulders 12 and a top 14, and reinforcing bars 15 may be embedded within them. Note that the support members 10 may be prefabricated in a factory or other facility (precast members), or may be constructed by casting on site.

As shown in Figure 5, the widthwise ends of the precast slab 20 are mounted on the shoulders 12 of each of a pair of support members 10 (10a, 10b), so that the precast slab 20 spans the opposing support members 10. For example, as shown in Figure 5(a), multiple precast slabs 20 may be installed along the length of the culvert, and in this case, the precast slabs 20 may be installed so that the reinforcement members 27 are positioned in the gaps formed between adjacent tops 14.

Furthermore, as shown in Figures 5(c) and (d), the precast slab 20 may have distribution bars 28 embedded in it, extending in the width direction of the precast slab 20, with their ends protruding from the precast slab 20. When multiple precast slabs 20 are installed, adjacent precast slabs 20 may be integrally constructed by connecting the distribution bars 28 with, for example, a joint structure. The specific configuration of the joint structure is arbitrary, and may be, for example, a loop joint, a mechanical joint, a half-flap joint, etc.

Then, as shown in Figure 6, a support 30 is installed above the precast slab 20 so that it spans the tops 14 of a pair of support members 10 (10a, 10b). At this time, a spacer 31 may be installed between the support 30 and the tops 14 to adjust the height of the support 30.

As shown in Figure 7, multiple hanging members 33 are then installed, extending downward from the support 30. For example, the upper ends of the hanging members 33 are connected to the support 30, and the lower ends are connected to the main body of the precast slab 20 or the reinforcing members 27, thereby firmly suspending the precast slab 20. Note that Figure 7 illustrates a configuration in which the hanging members 33 and the reinforcing members 27 are connected.

The means for connecting the shoring 30 and the hanging member 33 is arbitrary. For example, the upper end of the hanging member 33 may be externally threaded, a hole may be drilled in the shoring 30, and a nut (not shown) may be threaded through the drilled hole to engage with the external thread. Also, for example, in the configuration described with reference to Figure 3, the upper hanging member 33a may be connected to the shoring 30 in a similar manner.

The means for connecting the hanging member 33 to the precast slab 20 is optional. For example, the lower hanging member 33b described with reference to Figure 3 may be embedded in the precast slab 20 in advance. The upper hanging member 33a and lower hanging member 33b configured in this manner may be connected with a joint 35 to hang the precast slab 20.

When the precast slab 20 is suspended by the shoring 30 via the hanging member 33, the posture of the suspended precast slab 20 may be adjusted by raising or lowering the hanging member 33 at the connection point between the shoring 30 and the hanging member 33. The up and down movement of the hanging member 33 may be achieved, for example, by tightening or loosening the nut used as the connection means between the shoring 30 and the hanging member 33.

Then, as shown in Figure 8, a reinforcing steel structure 40 is constructed above the precast slab 20. At this time, at least a portion of the hanging member 33 may be anchored to one or both of the reinforcing bars 42 and main reinforcing bars 44 that make up the reinforcing steel structure 40. The reinforcing steel structure 40 may be constructed on-site, or may be prefabricated off-site and installed.

Then, as shown in Figure 9, concrete is poured and cured to bury at least a portion of the hanging material 33 and the reinforcing steel structure 40, forming a cast-in-place concrete section 50 (see the dashed line in the figure). As shown, concrete may be poured and cured so that the height of the top of the cast-in-place concrete section 50 matches the height of the upper end of the top 14 of the support member 10.

Then, as shown in Figure 10, at least a portion of the shoring 30 and the hanging member 33 are separated, and the shoring 30 is removed (see the dashed line in the figure). For example, in a configuration in which the upper hanging member 33a and the lower hanging member 33b are connected by a joint 35 as shown in Figure 3, the shoring 30 may be removed by disconnecting the joint 35 and removing the nut 35a and P cone 35b.

By using the construction method described above with reference to Figures 4 to 10, a top slab structure 1 is constructed as a slab-like member consisting of a precast slab 20 and a cast-in-place concrete section 50.

<Precast slab configuration>
The precast slab 20 may be a component prefabricated in a factory or the like, and its configuration is arbitrary. In other words, as long as it is possible to connect and hang the lower ends of the hanging members 33 (the lower ends of the lower hanging members 33b), the configuration is not limited. An example of the configuration of the precast slab 20 will be described below with reference to Figure 11. Figure 11 is a schematic explanatory diagram showing an example of the configuration of the precast slab 20, and both (a) and (b) are width-direction cross-sectional views.

As shown in Figure 11(a), one example of the configuration of the precast slab 20 is that the lower end of the hanging material 33 may be buried inside, and the buried location may have a protrusion 22 that protrudes above the precast slab 20. By providing the protrusion 22, it is possible to improve the anchoring efficiency and pull-out resistance when the hanging material 33 is buried in the precast slab 20. Also, as shown in the figure, one or more main reinforcing bars 24 may be buried inside the precast slab 20, extending in a direction perpendicular to the above-mentioned distribution bars 28 (longitudinal direction). This can improve the strength of the precast slab 20 itself.

As shown in Figure 11(b), one example of the configuration of the precast slab 20 is to install a steel plate 25 on its underside. In addition, a hanging member 33 embedded in the precast slab 20 may be joined to the steel plate 25. This not only improves the anchoring efficiency of the hanging member 33, but also makes it possible to suppress or tolerate the occurrence of cracks in the precast slab 20.

Fiber reinforced concrete (FRC), for example, may be used in the production of the precast slab 20. This increases the strength and toughness of the precast slab 20 itself. For example, if the precast slab 20 is reinforced with reinforcing materials 27 and the above-mentioned FRC and has sufficient bending rigidity to withstand the construction load before concrete is poured, the following construction procedure may be adopted. That is, after installing the precast slab 20, the reinforcing steel structure 40 may be constructed, and then shoring 30 may be installed to connect the hanging materials 33 to the main body of the precast slab 20 or the reinforcing materials 27, and the cast-in-place concrete section 50 may be formed by pouring concrete.

When constructing a reinforced concrete structure 40 with shoring 30 already installed, as described above with reference to Figures 4 to 10, work is carried out with the upper section partially closed off. This raises concerns about reduced work efficiency depending on the structural conditions. On the other hand, by installing the shoring 30 after constructing the reinforced concrete structure 40, the reinforced concrete structure 40 can be constructed with the upper section open, improving work efficiency for transporting materials and assembling rebar.

<Connection between precast slab and hanging material>
In the method for constructing the top slab structure 1 described above, the important step is to hang the precast slab 20 from the support 30 via the hanging members 33 described with reference to Figure 7. The connecting means and its configuration during hanging are not particularly limited as long as they can reliably connect the hanging members 33 and the precast slab 20. Here, an example of the connecting means and its configuration between the precast slab 20 and the hanging members 33 will be described.

Figure 12 is a schematic diagram illustrating the connection between the precast slab 20 and the hanging member 33, and shows a schematic diagram of the connection configuration. As shown in Figure 12, various configurations are possible when connecting the lower end of the hanging member 33 (the lower end of the lower hanging member 33b) to the precast slab 20.

For example, the lower end of the hanging member 33 (the lower end of the lower hanging member 33b) may be configured to have a fixing device 32, and the lower end of the hanging member 33, including the fixing device 32, may be embedded directly into the precast slab 20, as shown in Figure 12(a). This can improve the anchoring efficiency and pull-out strength of the hanging member 33 to the precast slab 20.

Alternatively, for example, as shown in Figure 12(b), an insert 36 may be embedded in the precast slab 20, and the lower end of a threaded hanging member 33 may be connected to the insert 36 for connection.

Alternatively, for example, as shown in Figure 12(c), a notch 37 may be formed in the precast slab 20, and a hanging member 33 having a fixing device 32 at its lower end may be inserted into the notch 37 and then filled with grout 38 to connect the slabs.

Alternatively, for example, as shown in Figure 12(d), a steel pipe 39 may be installed on the precast slab 20, and a hanging member 33 having a fixing device 32 at its lower end may be inserted into the steel pipe 39 and then filled with grout 38 to connect the two.

<Configuration of support>
As described above, H-shaped steel is exemplified as the shoring 30, and the connection to the hanging material 33 is made by drilling holes in the shoring 30, machining male threads at the upper ends of the hanging material 33, and then machining male threads and fastening nuts at the connection points between the shoring 30 and the hanging material 33. However, this is not limitative, and various configurations of the shoring 30 and the connection configuration with the upper ends of the hanging material 33 are possible.

Figure 13 is a schematic cross-sectional view of a case where a channel steel is used as the support 30. As shown in Figure 13, the support 30 may be composed of two channel steels 30a and 30b, with a hanging member 33 installed between the two channel steels 30a and 30b, and the hanging member 33 joined with an anchor plate 60 and a nut 61. This reduces the amount of hole drilling required.

When installing the shoring 30, a platform 70, such as an H-shaped steel beam, may be placed between the shoring 30 and the crest 14. Figure 21 is a schematic diagram of installing the shoring 30 via a platform 70 between the shoring 30 and the crest 14. For example, by installing the platform 70 so that it straddles adjacent crests 14 and installing the shoring 30 on the platform 70 at the center of the span between the adjacent crests 14, it is possible to design a larger installation distance between adjacent crests 14.

<Action and effect>
According to the method for constructing the top slab structure 1 as a slab-like member explained above, in the process of suspending the precast slab 20 using the shoring 30, the suspension members 33 are used, and at least a portion of the suspension members 33 is embedded in the cast-in-place concrete portion 50. As a result, at least a portion of the suspension members 33 functions as shear reinforcement in the top slab structure 1. In other words, sufficient shear strength is ensured in the top slab structure 1 as a slab-like member consisting of the precast slab 20 and the cast-in-place concrete portion 50.

Furthermore, by having the hanging members 33 function as shear reinforcement in the top slab structure 1, there is no need to arrange separate shear reinforcement, which improves workability in reinforcing bar work and shortens construction time. Additionally, by fabricating the reinforcing bar structure 40 off-site and unitizing it, the workability of reinforcing bar installation is improved.

Furthermore, when using shoring 30 to suspend the precast slab 20 via the hanging members 33, various connection configurations such as those described with reference to Figures 11 to 13 can be used to connect the precast slab 20 to the hanging members 33 and to connect the shoring 30 to the hanging members 33, thereby improving anchorage efficiency and pull-out resistance.

The above describes one example of an embodiment of the present invention, but the present invention is not limited to the illustrated form. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

For example, in the above embodiment, a configuration using a joint 35 was described as an example of a means for connecting the upper hanging member 33a and the lower hanging member 33b, but the connecting means is not limited to this. That is, the connecting means may be a through-type fixing body and a mechanical joint, and nuts and polystyrene foam box punches may also be used. Furthermore, turnbuckles may also be used to eliminate rattle during connection.

In the above embodiment, Figure 3 illustrates a configuration of the hanging member 33 in which the upper hanging member 33a and the lower hanging member 33b are connected by a joint 35, but the configuration of the hanging member 33 is not limited to this. Figure 22 is a schematic explanatory diagram showing another configuration example of the hanging member 33, where (a) is an overhead view and (b) is a side view. Note that in Figure 22, components having the same functional configuration as those in the above embodiment are illustrated with the same reference numerals, and their description may be omitted.

As shown in Figure 22, the hanging member 33 may be composed of, for example, a hook-shaped upper hanging member 33c made of non-metallic material and a hook-shaped lower hanging member 33d made of bamboo-node rebar or threaded rebar. These hook-shaped upper hanging member 33c and hook-shaped lower hanging member 33d are configured so that they can be locked and connected when butted against each other in the height direction. As shown, the hook-shaped upper hanging member 33c and hook-shaped lower hanging member 33d may be connected via the distribution bars 42 of the steel structure 40.

When constructing the top slab structure 1, the hook-shaped upper hanging member 33c can be left in place or cut off at the top surface of the cast-in-place concrete section 50. Because the hook-shaped upper hanging member 33c is made of a non-metallic material, rust prevention treatment is not required. By configuring the hanging member 33 in this way, it is no longer necessary to remove the hook-shaped lower hanging member 33d or to fill the box when using a box cutter, thereby saving labor.

<Another embodiment of the present invention>
In the above embodiment, a top plate structure 1 constructed by the method for constructing a slab-like member according to the present invention has been illustrated and described as an example, but the scope of application of the present invention is not limited to this. Specifically, the present invention can also be applied to the construction of a beam as a slab-like member. Below, as another embodiment of the present invention, a method for constructing a beam using the method for constructing a slab-like member according to the present invention will be described with reference to the drawings. Note that in the following description of another embodiment, components having the same functional configuration as those in the above embodiment will be illustrated with the same reference numerals, and their description may be omitted.

Figures 14 to 20 are process diagrams for constructing a beam 100 using the slab-like member construction method of the present invention, with the processes being carried out in the order shown in Figures 14 to 20. For explanatory purposes, each of Figures 14 to 20 includes a schematic plan view (a), a schematic side cross-sectional view (b), and an A-A cross-sectional view (c). Furthermore, Figures 5 to 10 also include a B-B cross-sectional view (d).

First, as shown in Figure 14, support members 110 (110a, 110b, 110c, 110d) are constructed as column members. The placement of the support members 110 is designed as desired depending on the structure of the beam 100. This embodiment illustrates the construction of a beam 100 that is approximately rectangular in plan view, with support members 110 positioned at four locations on all four sides. The support members 110 are constructed to include shoulder portions 112 and a peak portion 114 located above the shoulder portions 112. Reinforcing bars 115 that protrude upward may be embedded around the periphery of the shoulder portions 112. The support members 110 may be prefabricated in a factory or the like (so-called precast members), or may be constructed by casting on site.

As shown in Figure 15, the widthwise ends of the precast slab 20 are mounted on the opposing shoulders 112 of the support members 110 (110a, 110b, 110c, 110d), so that the precast slab 20 is suspended across the opposing support members 110. For example, as shown in Figure 15(a), four precast slabs 20 may be suspended in a roughly rectangular shape. Here, the reinforcing members 27 included in adjacent precast slabs 20 may be connected at the intersections 128 by means of welding or other means.

Then, as shown in Figure 16, shoring 30 is installed above the precast slab 20 so that it spans the tops 14 of the support members 110 (110a, 110b, 110c, 110d). At this time, spacers 31 may be installed between the shoring 30 and the tops 114 to adjust the height of the shoring 30.

As shown in Figure 17, multiple hanging members 33 are then installed, extending downward from the shoring 30. The upper ends of the hanging members 33 are connected to the shoring 30, and the lower ends are connected to the main body of the precast slab 20 or the reinforcing members 27, thereby firmly suspending the precast slab 20. Note that Figure 17 illustrates a configuration in which the hanging members 33 and the reinforcing members 27 are connected. The means of connecting the shoring 30 and the hanging members 33, and the means of connecting the hanging members 33 and the precast slab 20, are optional, and the connections may be made using the configuration described in the above embodiment.

Then, as shown in Figure 18, a reinforcing steel structure 40 is constructed above the precast slab 20. At this time, as in the above embodiment, at least a portion of the hanging member 33 may be moored to the reinforcing steel structure 40. The reinforcing steel structure 40 may be constructed on-site, or may be prefabricated off-site and installed.

Then, as shown in Figure 19, concrete is poured and cured to bury at least a portion of the hanging material 33 and the reinforcing steel structure 40, forming a cast-in-place concrete section 50 (see the dashed line in the figure). As shown, concrete may be poured and cured so that the height of the top of the cast-in-place concrete section 50 matches the height of the upper end of the peak 114.

Then, as shown in Figure 20, at least a portion of the support 30 and the hanging material 33 are separated, and the support 30 is removed (see the dashed line in the figure). As explained in the above embodiment, the support 30 may be removed, for example, by disconnecting the joint 35 and removing the nut 35a and P cone 35b.

As described above, the construction method described with reference to Figures 14 to 20 constructs a beam 100 as a slab-like member consisting of a precast slab 20 and a cast-in-place concrete section 50. In this way, by applying the construction method for a slab-like member according to the present invention to a beam-column structure, it is possible to improve workability and shorten construction time when constructing a beam 100, just as in the above embodiment.

Furthermore, the effects described in this specification are merely descriptive or exemplary and are not limiting. In other words, the technology disclosed herein may achieve other effects in addition to or in place of the above-mentioned effects that would be apparent to those skilled in the art from the description herein.

The following configurations also fall within the technical scope of the present invention.
(1) A method for constructing a slab-like member made of half precast concrete, which is made of a precast slab and cast-in-place concrete and is mounted across a pair of support members, comprising the steps of: mounting the widthwise ends of the precast slab on the pair of support members; suspending the precast slab from supports suspended above the precast slab via hanging members extending downward from the supports; constructing a steel structure above the precast slab; pouring and curing cast-in-place concrete above the precast slab so as to embed at least a portion of the hanging members and the steel structure; and separating the hanging members from the supports and removing the supports, wherein the hanging members embedded in the cast-in-place concrete in the slab-like member function as shear reinforcement.
(2) A method for constructing a slab-like member as described in (1), characterized in that the precast slab is reinforced by a reinforcing material embedded in the precast slab, and in the process of suspending the precast slab, the lower end of the suspending material is connected to the reinforcing material or the precast slab.
(3) A method for constructing a slab-like member described in (1) or (2), characterized in that the upper end of the hanging material is provided with a male thread, and in the process of hanging the precast slab, the hanging material is raised and lowered by tightening or loosening a nut that threads onto the male thread at the connection between the support and the hanging material, thereby adjusting the posture of the precast slab.
(4) A method for constructing a slab-like member described in any one of (1) to (3), characterized in that the hanging material has a structure in which an upper hanging material connected to the shoring and a lower hanging material connected to the precast slab are connected by joints, and in the process of removing the shoring, the lower hanging material is separated from the shoring by removing the joints.
(5) A method for constructing a slab-like member according to (4), characterized in that the lower hanging member has fixing devices at its upper and lower ends.
(6) A method for constructing a slab-like member described in any one of (1) to (5), characterized in that the support member has a shoulder portion and a top portion extending upward from the shoulder portion, the widthwise end portion of the precast slab is mounted on the shoulder portion, and the support is mounted so as to span the top portions of the pair of support members.
(7) A method for constructing a slab-like member described in any one of (1) to (6), characterized in that the support member is a wall of a culvert and the slab-like member is a top plate of the culvert.
(8) A method for constructing a slab-like member described in any one of (1) to (6), characterized in that the support member is a column and the slab-like member is a beam.
(9) A method for constructing a slab-like member described in any one of (1) to (8), characterized in that the reinforcement structure includes main reinforcement bars installed parallel to the width direction of the precast slab and distribution reinforcement bars installed in a direction intersecting the main reinforcement bars, and the hanging member is moored to one or both of the main reinforcement bars and the distribution reinforcement bars.
(10) A method for constructing a slab-like member described in any one of (1) to (7), characterized in that a plurality of the precast slabs are mounted adjacent to each other, distribution bars extending in the width direction of the precast slabs are embedded in the precast slabs so that the ends of the distribution bars protrude from the precast slabs, the distribution bars of adjacent precast slabs in the plurality of precast slabs are connected to each other with joints, and in the process of pouring and curing the cast-in-place concrete, concrete is poured including between adjacent precast slabs.
(11) A method for constructing a slab-like member described in (10), characterized in that the support member is a culvert wall, the slab-like member is the top plate of the culvert, and multiple precast slabs are installed in the longitudinal direction of the culvert.

The present invention can be applied to a construction method for constructing slab-like members made of half-precast concrete.

DESCRIPTION OF SYMBOLS 1...Top slab structure 10...Support member 12...Shoulder 14...Top 15...Reinforcing bar 20...Precast slab 27...Reinforcing material 28...(Precast slab) distribution bar 30...Support 33...Hanging material 34...Anchor 35...Joint 40...Reinforcing bar structure 42...Distribution bar 44...Main reinforcing bar 50...Caused-in-place concrete section 100...Beam

Claims (9)

A method for constructing a half-precast concrete slab-like member that is made of precast slab and cast-in-place concrete, and that is installed across a pair of support members that extend in the vertical direction and have shoulders and a top that extends upward from the shoulders, comprising:
placing widthwise ends of the precast slab on shoulder portions of the pair of support members;
a step of placing a support structure above the precast slab by placing its end on the top of the pair of support members;
A step of suspending the precast slab via a suspension member extending downward from a support structure suspended above the precast slab;
constructing a reinforcing steel structure above the precast slab;
Pouring and curing cast-in-place concrete onto the precast slab and the upper portion of the shoulder portion so as to embed at least a portion of the hanging material and the reinforcing bar structure until the upper surface position of the cast-in-place concrete coincides with the upper end of the top portion ;
Separating the hanging material from the support and removing the support,
A method for constructing a slab-like member, characterized in that the hanging members embedded in the cast-in-place concrete in the slab-like member function as shear reinforcement. The precast slab is reinforced by a reinforcing material embedded in the precast slab,
2. The method for constructing a slab-like member according to claim 1, wherein in the step of suspending the precast slab, the lower end of the suspension member is connected to the reinforcement member or the precast slab. A method for constructing a slab- like member as described in claim 1 or 2, characterized in that a male thread is machined on the upper end of the hanging material, and in the process of hanging the precast slab, the hanging material is raised and lowered by tightening or loosening a nut that engages with the male thread at the connection between the support and the hanging material, thereby adjusting the posture of the precast slab. The hanging member has a structure in which an upper hanging member connected to the support and a lower hanging member connected to the precast slab are connected by joints,
3. A method for constructing a slab-like member according to claim 1 or 2, characterized in that in the step of removing the support, the lower hanging member is separated from the support by removing the joint. A method for constructing a slab-like member as described in claim 4, characterized in that the lower hanging member has fixings at its upper and lower ends. 3. A method for constructing a slab-like member according to claim 1 or 2, characterized in that the support member is a wall of a culvert and the slab-like member is a top plate of the culvert. 3. A method for constructing a slab-like member according to claim 1 or 2, characterized in that the support members are columns and the slab-like members are beams. The reinforcing bar structure includes main reinforcing bars installed parallel to the width direction of the precast slab and distribution bars installed in a direction intersecting the main reinforcing bars,
3. The method for constructing a slab-like member according to claim 1 or 2, wherein the hanging member is anchored to one or both of the main reinforcing bars and the distribution bars. The precast slabs are installed adjacent to each other in the longitudinal direction of the culvert,
In the precast slab, a distribution bar extending in the longitudinal direction of the culvert is embedded so that the end of the distribution bar protrudes from the precast slab,
7. The method for constructing a slab-like member according to claim 6, wherein the precast slabs adjacent to each other are connected by joints at the distribution bars, and the process of pouring and curing the cast-in-place concrete includes pouring concrete between adjacent precast slabs.