Junction structure for beam and junction method for beam

Abstract

To enhance workability for a beam when the beam using precast concrete uses concrete differing in strength between an upper part and a lower part thereof.SOLUTION: A junction structure of a beam comprises: a half-precast concrete beam 22; a floor slab (half-precast concrete floor slab 42) provided to bridge the half-precast concrete beam 22; a precast concrete column 12 which has an end of the half-precast concrete beam 22 placed on its top surface; joint part concrete 14 which is cast at an upper joint part of the precast concrete column 12; and top concrete 24 which has smaller design standard strength than the half-precast concrete beam 22 and is cast over the half-precast concrete beam 22 and the top surface of the floor slab, the half-precast concrete beam 22 and the floor slab being a precast concrete composite beam 20 and a precast concrete composite floor slab.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a beam joining structure and a beam joining method.

Background Art

[0002] Patent Document 1 below describes a separate casting method in which high-strength concrete and normal-strength concrete of a beam and a floor are cast separately. In this method, high-strength concrete is cast into the beam form until it reaches the same level as the upper surface of the floor form, and then normal-strength concrete is cast on the high-strength concrete and on the floor form.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As shown in Patent Document 1 above, depending on the required strength, the strength of the concrete forming the upper part of the beam may be made smaller than that of the concrete forming the lower part of the beam.

[0005] When applying such a configuration to columns and beams using precast concrete, as an example, a method is to erect columns, support a beam formed of precast concrete between the columns with a shoring, and form the portion between the column and the beam, that is, the end of the beam, with in-situ concrete.

[0006] At this time, since the lower part of the beam is formed of high-strength concrete while the part integrated with the slab is formed of low-strength concrete, it is necessary to cast the in-situ concrete separately for the high-strength part and the low-strength part, which is time-consuming for construction.

[0007] In view of the above facts, an object of the present invention is to improve the workability of a beam when using concretes with different strengths for the upper and lower parts of the beam using precast concrete.

Means for Solving the Problems

[0008] The beam joint structure according to claim 1 includes a half-precast concrete beam, a floor slab spanned over the half-precast concrete beam, a precast concrete column with the end of the half-precast concrete beam placed on its upper surface, a joint concrete placed in the joint part above the precast concrete column, and top concrete having a design standard strength smaller than that of the half-precast concrete beam and placed over the upper surfaces of the half-precast concrete beam and the floor slab to form the half-precast concrete beam and the floor slab into a precast concrete composite beam and a precast concrete composite floor slab.

[0009] In the beam joint structure according to claim 1, the end of the half-precast concrete beam is placed on the precast concrete column. That is, the high-strength part at the lower part of the beam is formed of precast concrete over the entire length of the beam. Therefore, for the in-situ concrete forming the beam, only the top concrete, which is the low-strength part, needs to be placed.

[0010] Thereby, compared with the case where the beam end is formed of in-situ cast concrete and the concrete is placed separately for the upper and lower parts of the beam end, the placing work of the concrete forming the beam can be reduced.

[0011] Also, in this beam joint structure, the top concrete is placed over the upper surfaces of the half-precast concrete beam and the floor slab. Thereby, compared with the case where high-strength concrete is placed on the upper part of the beam and placed separately from the concrete of the floor slab, the placing work of the concrete can be reduced.

[0012] The joint structure of the beam according to claim 2 is the joint structure of the beam according to structural claim 1, wherein the joint portion concrete is reinforced with steel fibers.

[0013] In the joint structure of the beam according to claim 2, the joint portion concrete is reinforced with steel fibers. Thereby, the strength of the joint portion can be increased as compared with the case where it is not reinforced with steel fibers.

[0014] The joint structure of the beam according to claim 3 is the joint structure of the beam according to claim 1 or 2, wherein the end portion of the main reinforcement of the beam is disposed in the joint portion.

[0015] In the joint structure of the beam according to claim 3, the end portion of the main reinforcement of the beam is disposed in the joint portion. Thereby, even if the direction of the beam connected to the joint portion is freely set, it is not necessary to bend the main reinforcement, so that the construction is easy. For this reason, it is easy to arbitrarily set the direction of the beam, and for example, it is easy to form a building with a circular plan.

[0016] The joint structure of the beam according to claim 4 is the joint structure of the beam according to claim 1 or 2, wherein the floor slab is a half-precast concrete floor slab.

[0017] In the joint structure of the beam according to claim 4, the floor slab is formed by a half-precast concrete floor slab. Therefore, it is easier to span over the half-precast concrete beam than in the case of forming the floor slab with in-situ concrete, for example.

[0018] The method for joining beams according to claim 5 includes a step of placing the end portion of the half-precast concrete beam on the upper surface of the precast concrete column, a step of placing joint portion concrete in the joint portion above the precast concrete column, a step of spanning a floor slab over the half-precast concrete beam, and a step of placing top concrete having a design standard strength smaller than that of the half-precast concrete beam over the upper surfaces of the half-precast concrete beam and the floor slab to form the half-precast concrete beam and the floor slab into a precast concrete composite beam and a precast concrete composite floor slab.

[0019] In the method for joining beams according to claim 5, the end of the half-precast concrete beam is placed on the precast concrete column. That is, the high-strength portion at the lower part of the beam is formed of precast concrete over the entire length of the beam. Therefore, for the in-situ concrete forming the beam, only the top concrete, which is the low-strength portion, needs to be placed.

[0020] This can reduce the placing work of the concrete forming the beam as compared with the case where the beam end is formed of in-situ concrete and the concrete is placed separately for the upper and lower parts.

[0021] Also, in this method for joining beams, the top concrete is placed over the upper surfaces of the half-precast concrete beam and the floor slab. This can reduce the placing work of the concrete as compared with the case where high-strength concrete is placed on the upper part of the beam and placed separately from the concrete of the floor slab.

Advantages of the Invention

[0022] According to the present invention, in the case of using concretes with different strengths for the upper and lower parts of a beam using precast concrete, the constructability of the beam can be improved.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0024] Hereinafter, the beam joining structure according to an embodiment of the present invention will be described with reference to the drawings. Components denoted by the same reference numerals in the respective drawings mean the same components. However, unless otherwise specified in the specification, each component is not limited to one, and a plurality of them may exist.

[0025] Also, descriptions of overlapping configurations and reference numerals in the respective drawings may be omitted. Note that the present disclosure is not limited to the following embodiments, and appropriate changes can be made and implemented, such as omitting configurations, replacing with different configurations, and combining one embodiment and various modification examples within the scope of the object of the present disclosure.

[0026] <Beam Joining Structure> The beam joining structure according to an embodiment of the present invention is formed including a precast concrete column 12, joint portion concrete 14, a precast concrete composite beam 20, and a precast concrete composite floor slab 40.

[0027] (Precast Concrete Column) Column main reinforcement 12A protrudes from the upper end surface of the precast concrete column 12. The column main reinforcement 12A is arranged through the joint portion concrete 14 and is inserted into a mechanical joint 12B arranged on the bottom surface of the precast concrete columns 12 adjacent in the vertical direction.

[0028] The end of the half-precast concrete beam 22, which will be described later, is placed on the precast concrete column 12.

[0029] (Precast concrete composite beam) The precast concrete composite beam 20 includes a half-precast concrete beam 22, top concrete 24, main reinforcement bars 26, and stirrups 28.

[0030] The half-precast concrete beam 22 is spanned between two adjacent precast concrete columns 12 in the lateral direction. As described above, the end of the half-precast concrete beam 22 is placed on the precast concrete column 12.

[0031] The top concrete 24 is the concrete cast in place above the half-precast concrete beam 22. The design standard strength of the top concrete 24 is lower than that of the concrete forming the half-precast concrete beam 22.

[0032] The required bearing capacity of the concrete forming the precast concrete composite beam 20 is ensured by the half-precast concrete beam 22 with a high design standard strength in addition to the top concrete 24 with a low design standard strength.

[0033] In other words, the design standard strength of the half-precast concrete beam 22 is determined so that the required bearing capacity as a beam is ensured even if the design standard strength of the top concrete 24 and the design standard strength of the top concrete 44 forming the precast concrete composite floor slab 40 are made equal.

[0034] The main reinforcement bars 26 include upper end bars 26A and lower end bars 26B. The upper end bars 26A are arranged in the top concrete 24, and the ends protrude from the top concrete 24 and are arranged in the joint concrete 14. A fixture J is fixed to the ends of the upper end bars 26A.

[0035] The lower end reinforcement bars 26B are arranged within the half-precast concrete beam 22, and their ends protrude from the half-precast concrete beam 22 and are arranged in the joint part concrete 14. Fixing tools J are also fixed to the ends of the lower end reinforcement bars 26B.

[0036] As shown in FIG. 2(B), the web reinforcement bars 28 are arranged surrounding the upper end reinforcement bars 26A and the lower end reinforcement bars 26B. The lower part of the web reinforcement bars 28 is embedded in the half-precast concrete beam 22, and the upper part is embedded in the top concrete 24.

[0037] (Joint part concrete) The joint part concrete 14 shown in FIG. 1 is the joint part of the precast concrete composite beam 20 with respect to the precast concrete column 12. The joint part concrete 14 is formed of steel fiber reinforced concrete. The joint part concrete 14 has the same planar shape as the precast concrete column 12.

[0038] As shown in FIG. 2(A), two precast concrete composite beams 20 protruding from the opposing end faces of the joint part concrete 14 are arranged at an angle to each other in plan view. In other words, these precast concrete composite beams 20 are not arranged on the same straight line.

[0039] (Precast concrete composite floor slab) As shown in FIG. 2(B), the precast concrete composite floor slab 40 includes a half-precast concrete floor slab 42 (an example of the floor slab in the present invention) and top concrete 44.

[0040] The half-precast concrete floor slab 42 is a panel material spanned over the half-precast concrete beam 22. The half-precast concrete floor slab 42 is formed using, for example, an ALC (Autoclaved Lightweight aerated Concrete) panel. Note that the floor slab in the present invention may be formed using a steel deck plate or a cast-in-place concrete slab.

[0041] The top concrete 44 is in-situ concrete placed above the half-precast concrete floor slab 42 and is placed integrally with the top concrete 24 in the precast concrete composite beam 20.

[0042] <Beam joining method> To construct the above-described beam joining structure, first, as shown in FIG. 3, a half-precast concrete beam 22 is spanned over the precast concrete column 12. At this time, as shown in FIG. 2(A), the installation angle of the half-precast concrete beam 22 is adjusted. As shown in FIG. 3, the lower end bars 26B and the stirrups 28 are arranged in the half-precast concrete beam 22. The upper end portion of the stirrup 28 protrudes from the upper end surface of the half-precast concrete beam 22.

[0043] Next, as shown in FIG. 4, the upper end bars 26A are arranged, a formwork surrounding the area surrounded by the dashed line is placed, and the joint concrete 14 is placed.

[0044] Next, as shown in FIG. 5, a half-precast concrete floor slab 42 is spanned over the half-precast concrete beam 22. Note that in FIG. 5, the half-precast concrete beam 22 indicated by the dashed line in FIG. 2(A) is shown as a beam extending in the front-rear direction of the paper. This beam may or may not be present. Also, the process of constructing the floor slab (including the half-precast concrete floor slab 42) in the present invention may be carried out before the process of placing the joint concrete 14.

[0045] Next, as shown in FIG. 6, the top concretes 24 and 44 are placed above the half-precast concrete beam 22 and above the half-precast concrete floor slab 42 to form a precast concrete composite beam 20 and a precast concrete composite floor slab 40.

[0046] Finally, place the upper precast concrete column 12 on top of the joint part concrete 14. At this time, insert the column main reinforcement 12A protruding from the upper end surface of the joint part concrete 14 into the mechanical joint 12B arranged on the lower end surface of the upper precast concrete column 12. Fill the mechanical joint 12B with grout.

[0047] Through the above steps, the precast concrete composite beam 20 is joined to the precast concrete column 12. Also, the precast concrete composite floor slab 40 is spanned over the precast concrete composite beam 20.

[0048] <Function and Effect> In the beam joint structure and joint method according to the embodiment of the present invention, as shown in FIG. 1, the end of the half-precast concrete beam 22 is placed on the precast concrete column 12. That is, the lower high-strength part of the precast concrete composite beam 20 is formed of precast concrete over the entire length of the precast concrete composite beam 20.

[0049] Therefore, for the in-situ concrete forming the precast concrete composite beam 20, only the top concrete 24, which is the low-strength part, needs to be placed. As a result, compared with the case where the beam end is formed with in-situ cast concrete and the concrete is placed separately for the upper and lower parts of the beam end, the placing work of the concrete forming the beam can be reduced.

[0050] Also, in this beam joint structure, as shown in FIG. 2(B), the top concretes 24 and 44 are placed over the upper surfaces of the half-precast concrete beam 22 and the half-precast concrete floor slab 42. As a result, compared with the case where high-strength concrete is placed on the upper part of the beam and separated from the concrete of the floor slab, the placing work of the concrete can be reduced.

[0051] In addition, in this beam joint structure, as shown in FIG. 1, the joint portion concrete 14 is reinforced with steel fibers. Thereby, the strength of the joint portion concrete 14 can be increased as compared with the case where it is not reinforced with steel fibers.

[0052] In addition, in this beam joint structure, as shown in FIG. 2(A), the end portions of the main reinforcing bars 26 of the precast concrete composite beam 20 are arranged inside the joint portion concrete 14. Thereby, even if the orientation of the precast concrete composite beam 20 connected to the joint portion concrete 14 is freely set, it is easy to construct because it is not necessary to bend the main reinforcing bars 26. For this reason, it is easy to arbitrarily set the direction of the precast concrete composite beam 20, and for example, it is easy to form a building with a circular plan. Further, not limited to a circle, it is also easy to form a building with an annular plan formed by combining arcs having a plurality of curvatures.

[0053] In addition, in this beam joint structure, a floor slab on which the top concrete 44 is placed upward is formed by the half-precast concrete floor slab 42. Thereby, it is easier to span the half-precast concrete beam 22 as compared with the case where the floor slab is formed of, for example, in-situ concrete.

[0054] <Other Embodiments> In the above embodiment, the joint portion concrete 14 is made of steel fiber reinforced concrete, but the embodiments of the present invention are not limited to this. For example, the joint portion concrete 14 may be formed of the same concrete as the concrete forming the precast concrete column 12 or the half-precast concrete beam 22, and can be appropriately selected according to the required strength, workability, etc.

[0055] In addition, in the above embodiment, the end portions of the main reinforcing bars 26 of the precast concrete composite beam 20 are arranged inside the joint portion concrete 14. That is, the main reinforcing bars 26 of the precast concrete composite beam 20 are divided inside the joint portion concrete 14, but the embodiments of the present invention are not limited to this. For example, the main reinforcing bars 26 may be used as a through member inside the joint portion concrete 14.

[0056] In particular, when two precast concrete composite beams 20 joined to the opposing side surfaces of the joint portion concrete 14 are arranged in a straight line respectively, it is difficult to make the main reinforcement bars 26 pass through the joint portion concrete 14 as a through member, and it is difficult to make the construction difficult. Thus, the present invention can be implemented in various modes.

Explanation of Signs

[0057] 12 Precast concrete column 14 Joint portion concrete 20 Precast concrete composite beam 22 Half precast concrete beam 24 Top concrete 26 Main reinforcement bar 26A Upper end bar (main reinforcement bar) 26B Lower end bar (main reinforcement bar) 40 Precast concrete composite floor slab 42 Half precast concrete floor slab 44 Top concrete

Claims

1. Half precast concrete beams, A deck slab spanned across the half precast concrete beam; a precast concrete column on whose upper surface the end of the half precast concrete beam is placed; A joint concrete is poured into the upper joint of the precast concrete column; top concrete, which has a design standard strength smaller than that of the half-precast concrete beam and is poured over the upper surfaces of the half-precast concrete beam and the floor slab, thereby forming the half-precast concrete beam and the floor slab into a precast concrete composite beam and a precast concrete composite floor slab; A beam joint structure equipped with

2. The joint concrete is reinforced with steel fibers. The beam joint structure according to claim 1 .

3. The end of the main reinforcement of the beam is disposed in the joint portion. The beam joint structure according to claim 1 or 2.

4. The floor slab is a half precast concrete floor slab. The beam joint structure according to claim 1 or 2.

5. placing an end of a half precast concrete beam on an upper surface of the precast concrete column; Pouring joint concrete into the upper joint of the precast concrete column; A step of bridging a deck slab across the half precast concrete beam; A step of pouring top concrete having a design standard strength smaller than that of the half-precast concrete beam over the upper surfaces of the half-precast concrete beam and the floor slab to convert the half-precast concrete beam and the floor slab into a precast concrete composite beam and a precast concrete composite floor slab; A beam joining method comprising:

Images