Construction methods for prestressed concrete structures

Abstract

This invention provides a construction method for prestressed concrete structures that allows for easy support of PC steel materials along with reinforcing bars. [Solution] A method for constructing a prestressed concrete structure, in which a plurality of spacers 4 are attached to the reinforcement structure 1, each spacer 4 integrally comprising a main body 5 attached to the lower reinforcement 20 and the PC steel material 3, a lower reinforcement support part 6 that supports the lower reinforcement 20 at a certain height from the bottom line L1 in the finished state of the prestressed concrete structure, and a PC steel material support part 7 that supports the PC steel material 3 at different heights set for each spacer 4 from the bottom line L1, and each spacer 4 is attached to the lower reinforcement 20 and concrete is poured with the PC steel material 3 supported in the deflected state.

Description

Technical Field

[0001] The present invention relates to a construction method for prestressed concrete structures such as slabs and beams.

Background Art

[0002] When constructing prestressed concrete structures such as slabs and beams by in-situ casting, spacers are used to support reinforcing bars and PC steel materials at predetermined positions before concrete placement. As an example of a spacer, there was one formed by bending steel wires as in Patent Document 1 (Design Gazette).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, in order to apply tensile force to the PC steel material after placement, the PC steel material that is not under tension before concrete placement is in a deflected state, and it has been necessary to support it in that state. In such a deflected PC steel material, the position closer to the center is lower than the position closer to the edge in the planned structure formation area.

[0005] Therefore, in order to support the PC steel material in a deflected state, it has been necessary to use a plurality of spacers with different heights. On the other hand, the reinforcing bars are arranged at a constant height. Therefore, a plurality of spacers with a constant height for supporting the reinforcing bars and a plurality of spacers with different heights for supporting the PC steel material were separately required.

[0006] An object of the present invention is to provide a construction method for a prestressed concrete structure that easily supports PC steel materials together with reinforcing bars. [Means for solving the problem]

[0007] The present invention relates to a method for constructing a prestressed concrete structure having a reinforcement structure in which horizontally extending reinforcing bars and PC steel materials in a bent state are combined, wherein a plurality of spacers are attached to the reinforcement structure, and each of the plurality of spacers integrally comprises a main body attached to the lower reinforcing bars which are positioned below the PC steel materials and the PC steel materials, a lower reinforcing bar support portion provided on the lower side of the main body portion which supports the lower reinforcing bars at a certain height from the bottom line of the finished prestressed concrete structure, and a PC steel material support portion provided on the upper side of the main body portion which supports the PC steel materials at different heights set for each spacer from the bottom line, and each of the plurality of spacers is attached to the lower reinforcing bars and concrete is poured with the PC steel materials supported in the bent state.

[0008] With this configuration, each of the multiple spacers supports the horizontally extending reinforcing bars and also supports the deflected PC steel members, so it is only necessary to prepare spacers of the type corresponding to the deflection of the PC steel members. This makes the installation of spacers into the reinforcement structure easier.

[0009] Furthermore, in the construction method for the prestressed concrete structure, the PC steel support portion has an elastic claw that protrudes from the upper end of the main body, and the elastic claw may have an elastic force in the inward direction in the cross-section to prevent the PC steel placed in the PC steel support portion from detaching from the PC steel support portion.

[0010] With this configuration, PC steel materials can be easily supported by clamping them with elastic claws.

[0011] Furthermore, in the construction method for the prestressed concrete structure, the lower reinforcement support portion may be provided such that its support direction intersects, in a plan view, with respect to the support direction of the PC steel material in the PC steel material support portion, and may have a shape that is recessed laterally relative to the main body.

[0012] With this configuration, the spacer can be easily attached to the lower reinforcing bar by fitting the lower reinforcing bar into the recessed lower reinforcing bar support section.

[0013] Furthermore, in the construction method for the prestressed concrete structure, each of the plurality of spacers is provided with a branch-like portion that protrudes laterally from the main body, and the lower reinforcing bar support portion is provided extending from the recessed portion to the branch-like portion, and may be inclined in the installed state such that the inner side of the recessed portion is lower and the tip side of the branch-like portion is higher.

[0014] With this configuration, the lower reinforcing bar can be guided along the slope into the recessed portion of the lower reinforcing bar support.

[0015] Furthermore, in the construction method for the prestressed concrete structure, each of the multiple spacers may be made of resin and integrally molded.

[0016] With this configuration, the spacers are easy to handle due to their integrated shape.

[0017] Furthermore, in the construction method for the prestressed concrete structure, each of the plurality of spacers may have a different color depending on the set height of the PC steel support portion from the bottom line.

[0018] With this configuration, differences in height between the PC steel support sections can be easily distinguished by their colors. [Effects of the Invention]

[0019] As described above, according to the present invention, it is possible to provide a construction method for a prestressed concrete structure that simply supports PC steel materials together with reinforcing bars.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a schematic perspective view of a construction method for a prestressed concrete structure according to the present embodiment. [Figure 2] FIG. 2 is a schematic side view of a construction method for a prestressed concrete structure. [Figure 3] FIG. 3 is a schematic diagram of a first spacer used in the construction method for the prestressed concrete structure, where FIG. 3(a) shows a front view and FIG. 3(b) shows a side view. [Figure 4] FIG. 4 is a schematic diagram of a second spacer used in the construction method for the prestressed concrete structure, where FIG. 4(a) shows a front view and FIG. 4(b) shows a side view. [Figure 5] FIG. 5 is a schematic diagram of a spacer used in a construction method for a prestressed concrete structure according to a modified example, where FIG. 5(a) shows a front view, FIG. 5(b) shows a side view, and FIG. 5(c) shows a rear view. [Figure 6] FIG. 6 is a schematic diagram of the spacer of FIG. 5, where FIG. 6(a) shows a plan view and FIG. 6(b) shows a bottom view.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, a construction method for a prestressed concrete structure according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, the prestressed concrete structure to be constructed has a reinforcement structure 1 in which reinforcing bars 2 extending in the horizontal direction and PC steel materials 3 in a deflected state are combined, and for example, it is a floor slab of an apartment building. Further, this construction method uses a plurality of spacers 4 attached to the reinforcement structure 1.

[0022] PC steel members 3 are members used to apply tension to prestressed concrete structures. As shown in Figure 2, PC steel members 3 extend in the first horizontal direction (lateral direction in Figure 2) in a bent state due to gravity between a pair of end-support members. In this embodiment, PC steel members 3 are stranded wires and are housed in, for example, a polyethylene sheath. After the concrete is poured and gains strength, PC steel members 3 are fixed in place with tensile force applied from both ends. The cross-sectional shape of PC steel members 3 is circular.

[0023] Reinforcement bars 2, like those in general reinforced concrete structures, are members used to reinforce the prestressed concrete structure. Reinforcement bars 2 extend in a first horizontal direction and in a second direction perpendicular to the first horizontal direction (the direction perpendicular to the plane of the paper in Figure 2). Reinforcement bars 2 also have lower reinforcement bars 20 positioned below the PC steel bars 3. Although reinforcement bars 2 are also positioned above the PC steel bars 3, their illustration and explanation are omitted.

[0024] Spacer 4 is a member that supports the reinforcement structure 1 (reinforcing bars 2 and PC steel members 3). Each of the multiple spacer 4 integrally comprises a main body 5, a lower reinforcement support 6 provided on the lower side of the main body 5 and supporting the lower reinforcement bars 20 at a certain height from the bottom surface line in the finished state of the prestressed concrete structure, and a PC steel member support 7 provided on the upper side of the main body 5. Spacer 4 also has branch-like portions 8 that protrude laterally from the main body 5. Furthermore, spacer 4 has leg portions 9 provided on the lower side of the main body 5.

[0025] In the construction method of this embodiment, multiple types of spacers 4 with different heights, specifically two types of spacers 41 and 42 with different heights, are used. In this construction method, each of the multiple spacers 4 is attached to the lower reinforcing bar 20, and concrete is poured with the PC steel material 3 supported in a bent state (see Figure 2). That is, after the lower reinforcing bar 20 and PC steel material 3 are in place, the spacers 4 are attached to them for support. Note that there may be three or more types of spacers 4 used during construction.

[0026] The main body 5 is attached to the lower reinforcing bar 20 and the PC steel material 3. In this embodiment, the main body 5 is roughly U-shaped when laid on its side, as shown in Figures 3(a) and 4(a). Specifically, the main body 5 comprises a pair of wall sections 50 that extend in the height direction and a connecting section 51 that connects the upper ends of the pair of wall sections 50. In this embodiment, the main body 5 comprises an auxiliary connecting section 52 that connects the lower parts of the pair of wall sections 50. The height of the main body 5 differs between the first spacer 41 and the second spacer 42.

[0027] Each of the pair of wall sections 50 is, for example, a rectangular plate. The size and shape of the pair of wall sections 50 are the same. The height of the pair of wall sections 50 of the first spacer 41 is greater than the height of the pair of wall sections 50 of the second spacer 42.

[0028] The connecting portion 51 is, for example, a rectangular plate. The thickness of the connecting portion 51 is the same as the thickness of each wall portion 50. However, the thickness of the connecting portion 51 may be different from the thickness of each wall portion 50. In this embodiment, the connecting portion 51 is integrally molded with the pair of wall portions 50. Furthermore, the boundary between the connecting portion 51 and the wall portion 50, that is, the boundary formed by the horizontal end of the upper surface of the connecting portion 51 and the upper end of the outer surface of the wall portion 50, is a curved surface. The size and shape of the connecting portion 51 are the same for the first spacer 41 and the second spacer 42.

[0029] The auxiliary connecting portion 52 is, for example, a long plate. The auxiliary connecting portion 52 is also provided for reinforcement. In the first spacer 41, the auxiliary connecting portion 52 is positioned below the center in the height direction of the first spacer 41. In the second spacer 42, the auxiliary connecting portion 52 is positioned above the center in the height direction of the second spacer 42. Note that the main body portion 5 does not necessarily have to be equipped with the auxiliary connecting portion 52.

[0030] As shown in Figure 2, the PC steel support section 7 supports the PC steel 3 at different heights set for each spacer 4 from the bottom line; in this embodiment, at two different heights. Specifically, the PC steel support section 7 of the first spacer 41 supports the PC steel 3 at a first height. The PC steel support section 7 of the second spacer 42 supports the PC steel 3 at a second height, which is lower than the first height.

[0031] According to this construction method, each of the multiple spacers 4 supports the horizontally extending reinforcing bars 2 and also supports the deflected PC steel members 3. Therefore, it is only necessary to prepare spacers 4 of a type corresponding to the deflection of the PC steel members 3 (two types in this embodiment). In this way, since only a limited number of types (two types in this embodiment) of spacers 4 are needed, the installation of the spacers 4 to the reinforcement structure 1 becomes easier. The distance between adjacent spacers 4 is, for example, within 1800 mm.

[0032] The PC steel support section 7 has elastic claws 71 and 72 that protrude from the upper end of the main body section 5 (connecting section 51 in this embodiment). The elastic claws 71 and 72 have an elastic force in the inward direction in cross-section on the PC steel 3 placed in the PC steel support section 7, so as to prevent it from detaching from the PC steel support section 7. The elastic claws 71 and 72 are curved in shape and a pair is provided on one spacer 4. In this way, the PC steel 3 can be easily supported by being clamped by the elastic claws 71 and 72. In other words, the PC steel support section 7 can support the PC steel 3 without the need for the conventional method of tying the PC steel 3 to wire or the like.

[0033] In this embodiment, the distance between the pair of elastic claws 71 and 72 is narrower at the upper end compared to the central part in the vertical direction. Therefore, once the PC steel material 3 is held between the pair of elastic claws 71 and 72, it is difficult for it to come loose after being supported. Note that the pair of elastic claws 71 and 72 are not limited to this shape, and may be U-shaped. That is, the distance between the pair of elastic claws 71 and 72 may be the same at the central part and the upper end. In this case, the PC steel material 3 will be placed on the inner circumferential surface of the elastic claws 71 and 72. Furthermore, only one elastic claw 71 or 72 may be provided on a single spacer 4, in which case the PC steel material 3 may be supported by one elastic claw 71 or 72 and a fixed claw.

[0034] Furthermore, while the PC steel support portion 7 is preferable if it is claw-shaped, as it can be attached to any position on the PC steel 3, it is not limited to this, as long as it can support the PC steel 3. For example, the PC steel support portion 7 may be formed in a ring shape so as to pass through the PC steel 3.

[0035] As shown in Figures 3(b) and 4(b), the lower reinforcement support section 6 is provided such that its support direction intersects (in this embodiment, is perpendicular to, or the second direction) with respect to the support direction (first direction) of the PC steel material 3 in the PC steel material support section 7 when viewed from above. Furthermore, the lower reinforcement support section 6 has a shape that is recessed laterally relative to the main body section 5.

[0036] In this embodiment, the spacer 4 can be easily attached to the lower reinforcing bar 20 by fitting the lower reinforcing bar 20 into the recessed lower reinforcing bar support part 6. In other words, the lower reinforcing bar support part 6 can support the lower reinforcing bar 20 without the need for tying it to the lower reinforcing bar 20 with wire or the like, as was done in the past.

[0037] Furthermore, the lower reinforcing bar support section 6 is provided extending from the recessed portion (recessed section 60) to the branch-like section 8. In addition, the lower reinforcing bar support section 6 is inclined such that, when installed, the back side of the recessed section 60 is lower and the tip side of the branch-like section 8 is higher. Therefore, the lower reinforcing bar support section 6 can guide the lower reinforcing bar 20 into the recessed section 60 along the inclination. Note that the lower reinforcing bar support section 6 may also have a non-inclined shape, i.e., a horizontal shape. The thickness of the lower reinforcing bar support section 6 is the same as the thickness of the wall section 50, but it may be different from the thickness of the wall section 50.

[0038] The lower reinforcing bar support section 6 is attached to the reinforcing bar 2 by first fitting the reinforcing bar 2 into the lower reinforcing bar support section 6, and then fitting the PC steel support section 7 onto the PC steel 3.

[0039] The leg portion 9 is provided for temporary placement before inserting the reinforcing bars 2. The leg portion 9 is a plate-shaped portion that extends continuously from the lower end of the main body portion 5. In this embodiment, the lower end of the leg portion 9 includes a plate-shaped plate portion 90 extending in the height direction, a first extension portion 91 extending from one end of the lower end of the plate portion 90 in the first direction, and a second extension portion 92 extending from the other end of the lower end of the plate portion 90 in the first direction. The thickness of the plate portion 90 is the same as the thickness of the wall portion 50, but it may be different from the thickness of the wall portion 50.

[0040] In this embodiment, each of the multiple spacers 4 is made of resin and integrally molded, making the spacers easy to handle due to their integrated shape. Note that each spacer 4 may be made of a material other than resin; for example, it may be integrally molded from metal. Furthermore, each spacer 4 may be a structure formed by combining separate parts.

[0041] Furthermore, in this embodiment, each of the multiple spacers 4 has a different color depending on the set height from the bottom line of the PC steel support section 7. For example, the first spacer 41 has a different color from the second spacer 42. Therefore, the difference in the type of spacer 4, that is, the difference in height of the PC steel support section 7, can be easily distinguished by color. As a result, it is less likely that mistakes will occur when installing the spacers 41 and 42 during construction, and the inspection time during inspection of the prestressed concrete structure after construction can be shortened, and inspection errors are also less likely to occur.

[0042] The difference in color of the spacers 4 can be achieved by mixing colorants into the material of the spacers 4, or by applying paint after molding. Furthermore, each of the multiple spacers 4 may be easily distinguishable by differences in appearance other than color, such as having a different mark or different shapes in parts not directly related to function.

[0043] It should be noted that the construction method for prestressed concrete structures of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of one embodiment can be deleted.

[0044] In the above embodiment, the lower reinforcing bar support portion 6 had a shape that was recessed laterally relative to the main body portion 5, but it may also have a shape that is recessed on the lower side in the height direction relative to the main body portion 5. Furthermore, the lower reinforcing bar support portion 6 may not have a branch-like portion 8, and may be configured to support the lower reinforcing bar 20 with only the recessed portion 60. The lower reinforcing bar support portion 6 may also be composed of an elastic claw that is provided to protrude from the lower end of the main body portion 5.

[0045] In the above embodiment, the PC steel material support portion 7 was composed of elastic claws 71 and 72 provided so as to protrude from the upper end of the main body portion 5, but it may have a shape that is recessed in the lateral direction or the lower side in the height direction with respect to the main body portion 5.

[0046] In addition, the attachment of the lower reinforcing bar 20 to the lower reinforcing bar support portion 6 and the attachment of the PC steel material 3 to the PC steel material support portion 7 are not limited to clamping or fitting. For example, the lower reinforcing bar 20 may be fixed to the lower reinforcing bar support portion 6 by a separate member such as a wire, or the PC steel material 3 may be fixed to the PC steel material support portion 7.

[0047] Also, the spacer 4 may have a shape as shown in FIGS. 5(a) to 5(c), FIGS. 6(a), and 6(b). In this spacer 4, the auxiliary connecting portion 52 is disposed at the central portion in the height direction of the spacer 4.

Explanation of Reference Numerals

[0048] 1... Reinforcement structure, 2... Reinforcing bar, 3... PC steel material, 4... Spacer, 5... Main body portion, 6... Lower reinforcing bar support portion, 7... PC steel material support portion, 8... Branch portion, 9... Leg portion, 20... Lower reinforcing bar, 41... First spacer, 42... Second spacer, 50... Wall portion, 51... Connecting portion, 52... Auxiliary connecting portion, 60... Recessed portion, 71, 72... Elastic claws, 90... Plate portion, 91... First extending portion, 92... Second extending portion, B... Both-end support member

Claims

1. A construction method for a prestressed concrete structure having a reinforcement structure in which horizontally extending reinforcing bars and flexible PC steel members are combined, Using a plurality of spacers attached to the aforementioned reinforcement structure, Each of the aforementioned plurality of spacers is The lower reinforcing bars among the aforementioned reinforcing bars are positioned below the PC steel material, and the main body is attached to the PC steel material. A lower reinforcement support section is provided on the lower side of the main body and supports the lower reinforcement at a certain height from the bottom line of the finished prestressed concrete structure, A PC steel support section is provided on the upper side of the main body and supports the PC steel at different heights set for each spacer from the lower surface line, Equipped with an integrated system, A method for constructing a prestressed concrete structure, wherein each of the plurality of spacers is attached to the lower reinforcing bar, and concrete is poured with the PC steel material supported in the deflected state.

2. The PC steel support portion has an elastic claw that protrudes from the upper end of the main body portion. The method for constructing a prestressed concrete structure according to claim 1, wherein the elastic claw has an elastic force in the inward direction in the cross-section to prevent the PC steel material, which is placed in the PC steel material support portion, from detaching from the PC steel material support portion.

3. The method for constructing a prestressed concrete structure according to claim 1, wherein the lower reinforcing bar support portion is provided such that its support direction intersects, in a plan view, with respect to the support direction of the PC steel material in the PC steel material support portion, and has a shape that is recessed laterally relative to the main body portion.

4. Each of the aforementioned plurality of spacers is provided with a branch-like portion that protrudes laterally from the main body, The method for constructing a prestressed concrete structure according to claim 3, wherein the lower reinforcing bar support portion is provided extending from the recessed portion to the branch-like portion, and in the installed state, the inner side of the recessed portion is lower and the tip side of the branch-like portion is higher.

5. A method for constructing a prestressed concrete structure according to any one of claims 1 to 4, wherein each of the plurality of spacers is made of resin and integrally molded.

6. A method for constructing a prestressed concrete structure according to any one of claims 1 to 4, wherein each of the plurality of spacers has a different color according to the set height of the PC steel support portion from the lower surface line.

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