Precast concrete foundation beam structure and construction method

Abstract

To provide a suitable foundation beam structure, in a foundation beam using precast concrete.SOLUTION: In a foundation beam structure 1, a pair of precast concrete beam members 10 in which a beam main reinforcement 14 projects in a long-axis direction of a foundation beam 5 are mounted on a bottom plate so as to be adjacent to each other in a beam width direction of the foundation beam 5, a stirrup reinforcement 21 is arranged in a joint space S1 between the pair of precast concrete beam members 10 and a pile head part foundation 8 so as to surround the outer peripheral part of the beam main reinforcement 14, and post-cast concrete 20 is placed in the joint space S1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a precast concrete foundation beam structure and a construction method, and more particularly to a precast concrete foundation beam structure and a construction method in which a precast concrete foundation beam is formed using a plurality of precast concrete members. [Background technology]

[0002] The foundation beam structure of a building is often constructed using conventional construction methods. However, because the conventional construction methods increase the amount of work and time required for construction, precast concrete is sometimes used not only for the superstructure but also for the substructure, which is the foundation beam structure.

[0003] When using precast concrete for foundation beam structures, in large buildings such as condominiums and buildings, the beam depth and beam span of the foundation beams become large, so the precast concrete foundation beams become much heavier than precast concrete columns. For this reason, the lifting equipment used on site must be large enough to handle the weight of the foundation beams, which leads to increased construction costs.

[0004] In order to address these problems, Patent Document 1 discloses a construction method for a foundation structure in which the weight of each precast concrete beam member is reduced by forming a foundation beam by pouring in-place concrete between two precast concrete beam members and integrating them together. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-145575 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the invention described in Patent Document 1, it is necessary to place pre-assembled reinforcing bars between the two precast concrete beam members that make up the foundation beam, and also to arrange the two precast concrete beam members at a predetermined distance from each other, which increases the labor and costs involved in constructing the foundation beam.

[0007] Therefore, an object of the present invention is to provide a suitable foundation beam structure for a foundation beam using precast concrete. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the precast concrete foundation beam structure of the present invention is a foundation beam structure consisting of a foundation beam and a pile head foundation, characterized in that a pair of precast concrete beam members with main beam reinforcement protruding in the longitudinal direction of the foundation beam are placed on a base plate so as to be adjacent to each other in the beam width direction of the foundation beam, stirrup reinforcement is arranged in a first joint space between the pair of precast concrete beam members and the pile head foundation so as to surround the outer periphery of the main beam reinforcement, and concrete is poured in the first joint space.

[0009] It is preferable that the weight of each of the pair of precast concrete beam members is equal to or less than the weight of the precast concrete column member to be placed on the upper surface of the pile head foundation.

[0010] It is preferable that the pair of precast concrete beam members are placed on the base plate so as to be adjacent to each other with a gap therebetween in the beam width direction of the foundation beam.

[0011] It is preferable that the pair of precast concrete beam members each consists of a pair of small-cut precast concrete beam members facing each other in the center of the longitudinal direction with a second joint space between them, and that the second joint space has main beam reinforcement bars protruding from each of the pair of small-cut precast concrete beam members, the stirrup reinforcement bars being arranged to surround the outer periphery of the protruding main beam reinforcement bars, and the concrete is poured.

[0012] In the first joint space, it is preferable that the stirrup reinforcement surrounds the main beam reinforcement protruding from one of the pair of precast concrete beam members and the main beam reinforcement on the outer periphery of the main beam reinforcement protruding from the other precast concrete beam member.

[0013] It is preferable that the gap is filled with grout or the concrete is poured into the gap.

[0014] It is preferable that the pair of precast concrete beam members are joined to each other at their upper or lower ends.

[0015] It is preferable that the pair of precast concrete beam members are placed on the main surfaces of a precast plate placed on the base plate.

[0016] The method for constructing a precast concrete foundation beam structure according to the present invention is a method for constructing a foundation beam structure consisting of a foundation beam and a pile head foundation, characterized in that the pile head foundation is constructed on top of a precast pile, a pair of precast concrete beam members with main beam reinforcement protruding in the longitudinal direction of the foundation beam are placed on a base plate between the two pile head foundations so that they are adjacent to each other with a gap in the beam width direction of the foundation beam, stirrup reinforcement is arranged in the joint space between the pair of precast concrete beam members and the pile head foundation so as to surround the main beam reinforcement, and concrete is poured into the joint space. Effect of the Invention

[0017] According to the present invention, it is possible to provide a suitable foundation beam structure in a foundation beam using precast concrete. [Brief description of the drawings]

[0018] [Figure 1](a) is a front view of a foundation beam structure according to an embodiment of the present invention, (b) is a plan view of (a), (c) is an enlarged cross-sectional view of a beam at part A in (a), and (d) is a cross-sectional view of a beam at the joint space S1 indicated by the Id-Id cross-sectional line in (a). [Diagram 2] FIG. 2(a) is a side cross-sectional view of a precast concrete foundation beam according to an embodiment, and FIG. 2(b) is a rear view of (a). [Diagram 3] (a) is a front view of the pile head foundation being poured in the embodiment, (b) is a front view of the precast beam members being arranged, (c) is a front view of the joint space being reinforced, and (d) is a front view of the foundation beam when construction is completed. [Figure 4] FIG. 10(a) is a front view of a foundation beam structure according to a modified example, and FIG. [Diagram 5] FIG. 10A is a front view of a foundation beam structure according to another modified example, and FIG. 10B is a cross-sectional view of the foundation beam of FIG. [Figure 6] (a) is a front view of a precast beam member relating to yet another modified example, (b) is a cross-sectional view taken along the VIb-VIb cross-sectional line of (a), (c) is a front view of a precast beam member to be fitted with the precast beam member of (a), and (d) is a cross-sectional view taken along the VId-VId cross-sectional line of (c). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The following describes a foundation beam structure according to an embodiment of the present invention with reference to the accompanying drawings. The same or equivalent components are given the same reference numerals. In addition, in each drawing, for the sake of simplicity, illustrations of the belly braces and width stop braces, which are not characteristic of the invention, are omitted.

[0020] 1(a), (b), (c), and (d) show a foundation beam structure 1 of a foundation beam and a pile head foundation according to an embodiment of the present invention. The foundation beam structure 1 is constructed by integrating a foundation beam 5 formed of precast concrete foundation beam members 10, 10 (hereinafter referred to as precast beam members 10) installed so that their main surfaces abut each other, and a pile head foundation 8 connected to both ends of the foundation beam 5 and the head of a precast pile P by pouring post-cast concrete 20 between them. In this embodiment, if the column span S=10m and the length of the precast concrete column members 7 (hereinafter referred to as precast column members 7) constituting the column 6 is 3m, the weight per member is about 10t and the column cross section is 1200mm×1200mm. In addition, as the precast pile P, for example, a shell steel pipe concrete pile (SC pile) having a diameter of Φ=1000mm is poured.

[0021] The foundation beam 5 is a beam with a beam width W=700 mm, which includes precast beam members 10, 10 with a beam depth H=1800 mm, a length L=5250 mm, a beam width W1=350 mm, and a weight of about 8 t as components. As shown in Figs. 2(a) and (b), the precast beam member 10 is arranged so that the beam main reinforcement 14 protrudes from the end faces 12, 12 of the beam concrete 11 in the longitudinal direction. When the precast beam member 10 is placed on the base plate so as to be adjacent to the other precast beam member 10 to form the foundation beam 5, a gap is formed between the inner surface 16 of the precast beam member 10 facing the other precast beam member 10, and the force acting on one precast beam member 10 is not transmitted to the other precast beam member 10 except at the end of the foundation beam 5 (the joint space S1 described later). In addition, since the upper and lower ends of the inner surface 16 of the precast beam members 10, 10 are waterproofed after being placed on the base plate, the reinforcement is arranged so that the covering thickness is thin.

[0022] (joint structure) As shown in Fig. 1(a), (b), and (d), in the joint space S1, the beam main reinforcement 14 protruding from the axial end faces 12, 12 of the precast beam member 10 and the beam main reinforcement joint 9 arranged so as to protrude from the side of the pile head foundation 8 are joined via a mechanical joint 30. Furthermore, in this joint portion, stirrup reinforcement 21 arranged in the beam cross section so as to surround the outer periphery of the beam main reinforcement 14 and the beam main reinforcement joint 9, and core reinforcement 22 with hooks on both ends are arranged at a predetermined pitch in the beam longitudinal direction. Post-cast concrete 20 is poured in the joint space S1, and the foundation beam 5 and the pile head foundation 8 are integrated. In addition, the column main reinforcement (not shown) arranged so as to protrude from the upper surface of the pile head foundation 8 is joined to the mechanical joint (not shown) at the lower end of the precast column member 7. In addition, the precast column members 7 and the pile head foundation 8 are provided with predetermined structural and assembly reinforcement bars (not shown) to ensure the necessary strength and durability.

[0023] (How to build) As shown in FIG. 3(a), first, a pile head foundation 8 is formed by pouring predetermined reinforcement and concrete into the head of a prefabricated pile P, or by placing a precast pile cap member manufactured in a factory.

[0024] As shown in Fig. 3(b), next, the precast beam members 10, 10 are placed on the base plate between the pile head foundations 8 so that their main surfaces face each other with a gap between them and are adjacent to each other. In addition, the beam main reinforcement 14 and the beam main reinforcement joint 9 are connected to the joint space S1 between the pile head foundations 8 and the precast beam members 10, 10 via mechanical joints 30. The precast beam members 10, 10 are arranged so that the gap is as small as possible.

[0025] As shown in Figures 3(c) and 1(d), stirrup bars 21 and core bars 22 are arranged at predetermined intervals in the joint space S1 so as to surround the beam main bars 14 of one precast beam member 10 and some of the beam main bars 14 of the other precast beam member 10. After the arrangement of the bars, formwork (not shown) is assembled on the side of the joint space S1, and formwork support work is performed.

[0026] As shown in FIG. 3(d), post-cast concrete 20 is poured into the joint space S1, and after a predetermined period of curing, the formwork support is dismantled, the form is removed, and the foundation beam structure 1 is completed.

[0027] As described above, the foundation beam 5 and the pile head foundation 8 are integrated together to form the foundation beam structure 1.

[0028] According to the foundation beam structure 1 of this embodiment, the weight of each precast beam member 10 constituting the foundation beam 5 can be kept below the weight of each precast column member 7 constituting the column 6, and while a precast foundation beam is used in the foundation beam structure, the foundation beam structure can be easily constructed with a small lifting machine having the same capacity as when the foundation beam structure is constructed by a conventional construction method. In addition, there is no need to increase the capacity of the cranes at the precast factory, the trucks for transportation, etc. Furthermore, reinforcement is not required between the adjacent precast beam members 10, 10. In addition, formwork support can be omitted on the back of the precast beam member 10, and separators, etc. are also not required. Therefore, the construction labor and construction cost can be reduced, the foundation beam structure 1 can be easily constructed, and this is a suitable foundation beam structure for a foundation beam using precast concrete. In addition, although a gap is provided between the precast beam members 10, 10, the precast beam members 10, 10 are integrated at the end of the foundation beam 5, so they behave as one unit.

[0029] (Modification) In the above embodiment, the foundation beam 5 has two precast beam members 10 as components, but in order to make the weight of one precast beam member equal to or less than the weight of one precast column member 7 even when the foundation beam has a large beam depth or a long column span, for example, as shown in Figures 4(a) and (b), the foundation beam 5A may be configured with precast beam members 10A in which the beam main reinforcement 14 is divided into four pieces and joined by post-cast concrete 20 not only in the joint space S1 but also in the joint space S2 in the middle of the column span. Alternatively, the foundation beam may have more than four precast beam members as components.

[0030] In the above embodiment, the force acting on one precast beam member 10 is not transmitted to the other precast beam member 10, but for example, as shown in Fig. 5, a precast plate 40 may be installed on the base plate and the precast beam members 10, 10 may be placed on top of it so that the precast beam members 10, 10 behave as a single unit. Alternatively, the precast beam members 10, 10 may be fixed to the precast plate 40 with metal fittings or the like (not shown), or a recess may be provided in the precast plate and the lower end of the precast beam member 10 may be fitted into the recess.

[0031] In the above embodiment, the gaps are left as open spaces, but for example, the gaps may be made larger and filled with grout, or concrete may be poured at the same time as concrete is poured into the joint space S1 to integrate the precast beam members 10, 10. Alternatively, grout may be filled even if the gaps are not large.

[0032] In the above embodiment, a gap is provided between the precast beam members 10, 10, but for example, as shown in each drawing of Fig. 6, the precast beam members 10B, 10C may be integrated by a concave groove 17 along the longitudinal direction of one precast beam member 10B and a convex portion 18 that can fit into the concave groove 17, or by other methods, such as attaching metal fittings to the upper or lower ends of the precast beam members. Alternatively, the precast beam members may be made of half precast concrete, and then integrated by pouring post-cast concrete 20 along the longitudinal direction.

[0033] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention. [Explanation of symbols]

[0034] 1,2,3 Foundation beam structure 5,5A foundation beam 6 Pillars 7 Precast concrete column members (precast column members) 8 Pile head foundation 9 Beam main reinforcement connection reinforcement 10, 10A, 10B, 10C Precast concrete foundation beam members (precast beam members) 11 Beam Concrete 12,13 End face 14 Main beam reinforcement 15,21 Stirrup muscle 16 Inner Surface 20 Post-cast concrete 30 Mechanical couplings 40 Precast Plate P Prefabricated pile S1,S2 joint space

Claims

1. A foundation beam structure consisting of a foundation beam and a pile head foundation, A pair of precast concrete beam members having beam main reinforcements protruding in the longitudinal direction of the foundation beam are placed on the base plate so as to be adjacent to each other in the beam width direction of the foundation beam, Stirrup reinforcements are arranged in a first joint space between the pair of precast concrete beam members and the pile head foundation so as to surround the outer periphery of the beam main reinforcement, Concrete is poured into the first joint space. A precast concrete foundation beam structure.

2. The weight of each of the pair of precast concrete beam members is equal to or less than the weight of the precast concrete column member to be placed on the upper surface of the pile head foundation.

2. The precast concrete foundation beam structure of claim 1.

3. The pair of precast concrete beam members are placed on the base plate so as to be adjacent to each other with a gap therebetween in the beam width direction of the foundation beam.

2. The precast concrete foundation beam structure of claim 1.

4. The pair of precast concrete beam members each include a pair of small precast concrete beam members facing each other at the center in the longitudinal direction with a second joint space therebetween, In the second joint space, the beam main reinforcement protrudes from each of the pair of small-split precast concrete beam members, the stirrup reinforcement is arranged so as to surround the outer periphery of the protruding beam main reinforcement, and the concrete is poured.

2. The precast concrete foundation beam structure of claim 1.

5. In the first joint space, the stirrup reinforcement surrounds the beam reinforcement protruding from one of the pair of precast concrete beam members and the beam reinforcement at the outer periphery of the beam reinforcement protruding from the other precast concrete beam member.

2. The precast concrete foundation beam structure of claim 1.

6. The gap is filled with grout or the concrete is poured into the gap.

4. The precast concrete foundation beam structure of claim 3.

7. The upper or lower ends of the pair of precast concrete beam members are joined to each other.

2. The precast concrete foundation beam structure of claim 1.

8. The pair of precast concrete beam members are placed on the main surfaces of the precast plate placed on the base plate.

2. The precast concrete foundation beam structure of claim 1.

9. A method for constructing a foundation beam structure including a foundation beam and a pile head foundation, comprising: Constructing the pile head foundation on the top of the prefabricated pile; Between the two pile head foundations, a pair of precast concrete beam members having beam main reinforcement protruding in the longitudinal direction of the foundation beam are placed on the base plate so as to be adjacent to each other with a gap in the beam width direction of the foundation beam, Stirrup reinforcements are arranged in the joint space between the pair of precast concrete beam members and the pile head foundation so as to surround the beam main reinforcement, Pour concrete into the joint space; A method for constructing a precast concrete foundation beam structure.

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