Reinforced concrete structure

Abstract

To prevent cracks from forming in walls while maintaining beam widths.SOLUTION: A reinforced concrete structure includes concrete beams extending in one direction, and concrete walls which are joined to the beams and narrower in widths than the beams, and edge separating portions are provided in the central portion of the beams in the width direction to prevent the cross-sections of the beams on one side in the width direction from being integrated with those of the beams on the other side in the width direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to reinforced concrete structures. [Background technology]

[0002] The reinforced concrete structure described in Patent Document 1 is a reinforced concrete structure having a pair of columns and a precast concrete beam whose both ends are joined to the pair of columns, and the precast concrete beam is made up of multiple precast concrete beam pieces divided in the width direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-6859 A Summary of the Invention [Problem to be solved by the invention]

[0004] Beams generally have less drying shrinkage than walls because their cross section is restrained by stirrups, and the larger the width of the beam's integrated cross section (= the width that is restrained integrally by one set of stirrups and is integrated with the concrete), the greater the axial rigidity of the beam and the smaller the drying shrinkage tends to be. Also, when a concrete beam of different widths is joined to a concrete wall, cracks may occur in the wall due to the difference in the amount of drying shrinkage after the concrete is poured.

[0005] Here, the width of the beam is determined by the force acting on the beam. If the width of the beam is different from the width of the wall, the amount of drying shrinkage of the beam and the wall that occurs after pouring concrete in the longitudinal direction of the beam will differ. This will cause cracks in the wall, which is narrower than the width of the beam.

[0006] The objective of the present disclosure is to suppress the occurrence of cracks in walls while maintaining a beam width that is effective in terms of structural planning. [Means for solving the problem]

[0007] The reinforced concrete structure of the first embodiment comprises a concrete beam extending in one direction, and a concrete wall extending in the one direction, joined to the beam, and narrower in width than the beam, and is characterized in that a cutting edge is provided in the central portion of the width of the beam to prevent the cross-sections of the beam on one side in the width direction from being integrated with those of the beam on the other side in the width direction.

[0008] According to the above-mentioned embodiment, a cut-off portion is provided that prevents the cross-sections of the beams on one side in the width direction from being integrated with those of the beams on the other side in the width direction. This reduces the difference between the drying shrinkage force generated in the wall and the drying shrinkage force generated in the beams at the portion where the wall is joined, thereby making it possible to suppress the occurrence of cracks in the wall while maintaining the width of the beams that is effective in the structural design.

[0009] The reinforced concrete structure of the second aspect is the reinforced concrete structure described in the first aspect, characterized in that the beam portion on one side and the beam portion on the other side are arranged with the edge separation portion between them.

[0010] According to the above aspect, the beam portion on one side and the beam portion on the other side are disposed with the edge separation portion therebetween, which makes it easier to prevent the cross sections from being integrated, compared to a case in which the integration of the cross sections is prevented by forming a slit between the beam portion on one side and the beam portion on the other side.

[0011] A reinforced concrete structure according to a third aspect is the reinforced concrete structure according to the second aspect, characterized in that the edge separation portion is a sheet member made of resin.

[0012] According to the above-mentioned embodiment, the resin sheet member is used to prevent the cross-sections of the beams on one side in the width direction from being integrated with the cross-sections of the beams on the other side in the width direction. Therefore, the cross-sections can be prevented from being integrated more effectively than when a lath formwork is used. Effect of the Invention

[0013] According to the present disclosure, it is possible to suppress the occurrence of cracks in walls while maintaining a beam width that is effective in terms of structural planning. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing a reinforced concrete structure according to an embodiment of the present disclosure. [Diagram 2] 1A and 1B are process diagrams showing a construction process for a reinforced concrete structure according to an embodiment of the present disclosure. [Diagram 3] 1A and 1B are process diagrams showing a construction process for a reinforced concrete structure according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a cross-sectional view showing a reinforced concrete structure according to a comparative example to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An example of a reinforced concrete structure according to an embodiment of the present disclosure will be described with reference to Figures 1 to 4. Arrow H shown in each figure indicates the up-down direction, i.e., the vertical direction, arrow W shown in each figure indicates the width direction perpendicular to arrow H and also the horizontal direction, and arrow D shown in each figure indicates the depth direction perpendicular to arrows H and W and also the horizontal direction.

[0016] (Overall composition) 1, the reinforced concrete structure 100 of this embodiment includes a concrete foundation beam 10 extending in the depth direction formed on a basing concrete 50, and a concrete floor slab 30 formed on the foundation beam 10. Furthermore, the reinforced concrete structure 100 includes a concrete wall 40 formed on the floor slab 30 and joined to the foundation beam 10 via the floor slab 30.

[0017] [Foundation beam 10] The foundation beam 10 is formed by pouring concrete on-site, and has a rectangular shape extending in the vertical direction and in the depth direction as shown in Fig. 1. The foundation beam 10 is an example of a beam, and the depth direction is an example of one direction.

[0018] The foundation beam 10 includes rectangular stirrups 12, 14 spaced apart in the depth direction, main reinforcements 16 extending in the depth direction and constrained by the stirrups 12 at the four corners of the stirrups 12, and main reinforcements 18 extending in the depth direction and constrained by the stirrups 14 at the four corners of the stirrups 14. Specifically, the stirrups 12 spaced apart in the depth direction and the stirrups 14 spaced apart in the depth direction are aligned in the width direction, and the stirrups 14 are arranged on one side of the stirrups 12 in the width direction (the right side in the figure). Details of the foundation beam 10 will be described later.

[0019] [Floor slab 30] The floor slab 30 is formed by pouring concrete on-site at the same time as the foundation beams 10, and is a plate with the thickness direction being in the vertical direction, as shown in Figure 1. The floor slab 30 is equipped with upper reinforcement bars 32 and lower reinforcement bars 34 that are spaced apart in the depth direction, and with distribution reinforcement bars (not shown).

[0020] [Wall 40] The wall 40 is formed by pouring concrete on-site after the foundation beams 10 and floor slab 30 are constructed, and is in the form of a plate extending in the depth direction with the width direction being the plate thickness direction as shown in Fig. 1. The width (thickness) of the wall 40 is narrower than the width of the foundation beams 10. The wall 40 also includes vertical reinforcement bars 42 that extend upward from the foundation beams 10 and are arranged at intervals in the depth direction, and horizontal reinforcement bars (not shown).

[0021] (Main part configuration) Next, the configuration of the foundation beam 10 and a construction method for the foundation beam 10 will be described. [Configuration of foundation beam 10] The cross section of the foundation beam 10 is rectangular extending in the vertical direction, and as mentioned above, stirrup reinforcement 14 and main reinforcement 18 are arranged on one side of the width of the foundation beam 10, and stirrup reinforcement 12 and main reinforcement 16 are arranged on the other side of the width of the foundation beam 10.

[0022] Furthermore, a resin sheet member 20 is provided in the center of the width of the foundation beam 10 to separate one side of the foundation beam 10 from the other side of the width. The sheet member 20 is an example of an edge separation portion.

[0023] The sheet member 20 is a so-called moisture-proof sheet that prevents the permeation of moisture and water vapor, and the base end portion of the sheet member 20 is embedded in the disposable concrete 50, and the tip portion of the sheet member 20 protrudes upward from the disposable concrete 50. The part of the sheet member 20 that protrudes upward is arranged so that the sheet surface faces the width direction. A metallic reinforcing plate 22 that reinforces the tip of the sheet member 20 is attached to the tip of the sheet member 20 by welding or the like. This reinforcing plate 22 extends in the depth direction, and through holes (not shown) are arranged at intervals in the depth direction in the reinforcing plate 22.

[0024] A wire 24 is inserted into this through hole (not shown), and this wire 24 is wrapped around the main reinforcement bars 16 and 18.

[0025] In this configuration, the part of the foundation beam 10 on one side in the width direction is separated from the part of the foundation beam 10 on the other side by the sheet member 20. This prevents the part of the foundation beam 10 on one side in the width direction from being integrated with the part of the foundation beam 10 on the other side in the depth direction after concrete is poured.

[0026] [Construction method of foundation beam 10] 2(A), a basing concrete 50 is poured into the ground. Here, the base end portion of the sheet member 20 is embedded in the basing concrete 50.

[0027] 2(B), the formwork (not shown) for the foundation beam 10 is assembled, the main reinforcements 16, 18 and the stirrups 12, 14 are assembled, and the base end portions of the vertical reinforcements 42 are attached to the stirrups 14, etc. Furthermore, the formwork (not shown) for the floor slab 30 is assembled, and the upper reinforcements 32, lower reinforcements 34, and distribution reinforcements (not shown) are assembled.

[0028] Here, a wire 24 is inserted into the through hole of the reinforcing plate 22 attached to the end of the sheet member 20, and the inserted wire 24 is wrapped around the main reinforcements 16 and 18. By wrapping the wire 24 around the main reinforcements 16 and 18, the reinforcing plate 22 is positioned, the sheet surface of the sheet member 20 faces the width direction, and the sheet member 20 is placed between the stirrups 12 and 14.

[0029] In this state, concrete is poured into the formwork to form the foundation beam 10 and floor slab 30, as shown in Fig. 3(A). Here, in the foundation beam 10, concrete is poured on one side and the other side of the sheet member 20, respectively.

[0030] Next, a formwork (not shown) for the wall 40 is assembled, and concrete is poured into the formwork, forming the wall 40 as shown in FIG. 3(B).

[0031] (action) Next, the function of the reinforced concrete structure 100 (hereinafter "structure 100") will be described while comparing it with a reinforced concrete structure 200 (hereinafter "structure 200") according to a comparative embodiment. First, the structure 200 according to the comparative embodiment will be described, mainly focusing on the differences from the structure 100.

[0032] As shown in Figure 4, the comparative structure 200 comprises a concrete foundation beam 210 extending in the depth direction formed on a basin concrete 50, a concrete floor slab 30 formed on the foundation beam 210, and a concrete wall 40 joined to the foundation beam 10 via the floor slab 30.

[0033] The foundation beam 210 includes rectangular stirrups 212 spaced apart in the depth direction and main reinforcements 216 extending in the depth direction and restrained by the stirrups 212 at their four corners. The stirrups 212 of the foundation beam 210 are larger than the stirrups 12, 14 of the foundation beam 10, and the sheet member 20 is not provided on the foundation beam 210. In other words, the foundation beam 210 is integrally formed. The cross-sectional area of ​​the foundation beam 210 is equal to that of the foundation beam 10.

[0034] In the structures 100 and 200, concrete is poured on-site to form the foundation beams 10 and 210 and the walls 40, and drying shrinkage occurs in the depth direction after pouring the concrete. The foundation beams 10 and 210 are made wider than the walls 40, which increases the axial rigidity of the beams. Therefore, the foundation beams 10 and 210 shrink less in the depth direction than the walls 40.

[0035] Therefore, due to the difference between the amount of drying shrinkage of the foundation beams 210 and the amount of drying shrinkage of the wall 40, cracks extending in the vertical direction may occur in the lower end portion of the wall 40.

[0036] In contrast, in the foundation beam 10 according to this embodiment, the part of the foundation beam 10 on one side in the width direction is separated from the part of the foundation beam 10 on the other side by the sheet member 20. Therefore, integration of the cross section in the depth direction that occurs after pouring concrete is prevented between the part of the foundation beam 10 on one side in the width direction and the part of the foundation beam 10 on the other side.

[0037] For this reason, the difference in the amount of drying shrinkage caused by the foundation beams 10 relative to the wall 40 is smaller than the difference in the amount of drying shrinkage caused by the foundation beams 210 relative to the wall 40. Cracks occurring in the lower end portion of the wall 40 are suppressed.

[0038] (summary) As described above, in the structure 100, the sheet member 20 that prevents the cross-sections of the part of the foundation beam 10 on one side in the width direction from being integrated with the part of the foundation beam 10 on the other side in the width direction is disposed. This makes it possible to suppress the occurrence of cracks in the wall 40 while maintaining the width of the foundation beam 10.

[0039] Furthermore, in the structure 100, the portion of the foundation beam 10 on one side in the width direction and the portion of the foundation beam 10 on the other side in the width direction are disposed with the sheet member 20 sandwiched therebetween. This makes it possible to easily prevent integration of the cross sections compared to the case where integration of the cross sections is prevented by forming a slit between the portion of the foundation beam 10 on one side and the portion of the foundation beam 10 on the other side.

[0040] Furthermore, in the structure 100, the integration of the cross sections is prevented by using the resin sheet member 20. This makes it possible to prevent the integration of the cross sections more effectively than in the case where the integration of the cross sections is prevented by using a lath formwork.

[0041] Although the present disclosure has been described in detail with respect to a specific embodiment, it is clear to those skilled in the art that the present disclosure is not limited to the embodiment, and various other embodiments can be adopted within the scope of the present disclosure. For example, although not specifically described in the above embodiment, the range in which the sheet member 20 is provided in the depth direction (longitudinal direction) of the foundation beam 10 is preferably 100, but may be 70 or more, or may be 40 or more, and may be provided only in the part of the wall 40 where cracks are likely to occur, assuming that the length of the foundation beam 10 in the longitudinal direction is 100.

[0042] In addition, in the above embodiment, the vertical range in which the sheet member 20 is provided is the entire foundation beam 10, but it is sufficient if the restraining force on the wall 40 is weaker than when it is formed integrally, and the vertical range in which the sheet member 20 is provided is preferably 50 or more, and more preferably 80 or more, when the entire vertical range is 100.

[0043] In addition, in the above embodiment, the vertical range in which the sheet member 20 is provided is the entire foundation beam 10, but it is sufficient that the restraining force on the wall 40 is weaker than when it is formed integrally, and in terms of the range in which the sheet member 20 is provided in the vertical direction of the foundation beam 10, providing it only in the upper part with respect to the vertical center of the foundation beam 10 can more effectively suppress cracks that occur in the wall 40 than providing it only in the lower part with respect to the vertical center of the foundation beam 10.

[0044] In addition, in the above embodiment, the sheet member 20 is used as an edge cutting portion that prevents the cross sections from being integrated, but a lath formwork, Styrofoam (registered trademark), etc. may be used. In this case, the effect of using the sheet member 20 as an edge cutting portion is not achieved.

[0045] In addition, in the above embodiment, the foundation beam 10 has been taken as an example of the beam, but other beams may be used.

[0046] In addition, in the above embodiment, the foundation beam 10 and the floor slab 30 are aligned in the vertical direction, the floor slab 30 is placed on top of the foundation beam 10, and the wall 40 is joined to the foundation beam 10 via the floor slab 30, but the foundation beam 10 and the floor slab 30 may be aligned in the width direction, the upper surface of the foundation beam 10 and the upper surface of the floor slab 30 may be arranged on the same plane, and the wall 40 may be joined directly to the foundation beam 10. [Explanation of symbols]

[0047] 10 Foundation beam (example of beam) 20 Sheet member (an example of an edge cutting part) 40 Wall 100 Structures (reinforced concrete structures) 200 Structures (reinforced concrete structures)

Claims

1. A concrete beam extending in one direction; a concrete wall extending in the one direction, joined to the beam, and narrowed relative to the beam; A reinforced concrete structure, wherein a border portion is provided in a central portion of the beam in a width direction to prevent integration of cross sections between a portion of the beam on one side in the width direction and a portion of the beam on the other side in the width direction.

2. The beam portion on the one side and the beam portion on the other side are arranged with the edge cutting portion therebetween.

2. The reinforced concrete structure according to claim 1.

3. The edge cutting portion is a resin sheet member.

3. The reinforced concrete structure according to claim 2.

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