PCa foundation block joining structure

Abstract

To provide the joint structure of a PCa foundation block applicable to buildings of large and small various scales without causing construction cost increase and without restrictions on the dimensions, specifications for an embedded plate, and the number of bolts, and having high joint strength between two PCa foundation blocks.SOLUTION: Provided is a joint structure 100 of reinforced concrete PCa foundation blocks forming a rising part of foundation. In a space 35 between end faces 31 of two PCa foundation blocks 30, upper end reinforcements 13 and lower end reinforcements 14 are extended from each end face 31. In the space 35, the upper end reinforcements 13 and the lower end reinforcements 14 are jointed to a common embedded plate 40 by welding. The two embedded plates 40 are jointed by bolts via splice plates 50. The space 35 is closed by cast-in-place concrete 70.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a joint structure of PCa foundation blocks.

Background Art

[0002] In the foundation of a building, in order to shorten the construction period of the foundation and improve the dimensional accuracy of the foundation, the rising part of the foundation is manufactured as a precast concrete foundation block (PCa foundation block) at a factory, and this PCa foundation block is transported to the construction site and used for the construction of the foundation.

[0003] A plurality of PCa foundation blocks transported to the construction site are laid side by side in the extending direction of the foundation with a gap. From the end of the PCa foundation block to the side, the ends of main reinforcement bars such as upper end reinforcement bars and lower end reinforcement bars extending in the extending direction of the foundation protrude. The ends of the main reinforcement bars of two PCa foundation blocks laid side by side on the left and right of the gap are connected using a mechanical joint in the gap, and after filling the inside of the mechanical joint with grout to integrate the reinforcement bars, the gap is closed with in-situ concrete, so that a foundation such as a strip foundation capable of stress transmission between adjacent PCa foundation blocks can be constructed.

[0004] In addition to connecting the main reinforcement bars through a mechanical joint and integrating the main reinforcement bars by filling grout, an embedded plate is welded to the end of the main reinforcement bar, and after bolt-joining the embedded plates protruding from the ends of adjacent PCa foundation blocks into the gap, there is also a form in which the foundation is constructed by embedding both embedded plates with in-situ concrete. In this form, for example, individual embedded plates are welded to the upper end reinforcement bar and the lower end reinforcement bar protruding from the end of the PCa foundation block, respectively. In the gap, the embedded plates of the upper end reinforcement bars protruding from the ends of the two PCa foundation blocks are bolt-joined, and the embedded plates of the lower end reinforcement bars are bolt-joined.

[0005] In the PCa foundation block joint structure described above, where reinforcing bars are connected using mechanical joints, there are challenges such as high construction costs due to the high cost of the mechanical joints themselves, as well as the high cost of the grout used to fill them. Furthermore, measures to prevent grout leakage may involve the use of standard sealants or the addition of extra furring to the foundation, which also contribute to increased construction costs and labor.

[0006] Furthermore, in the joint structure of precast concrete (PCa) foundation blocks, where embedded plates welded to the main reinforcement bars are bolted together, the embedded plates of the upper reinforcement bars are bolted together, and the embedded plates of the lower reinforcement bars are bolted together. This naturally limits the dimensions and specifications of the embedded plates, as well as the number of bolts that can be used, potentially restricting the scope of construction to relatively small buildings.

[0007] Therefore, a PCa foundation block joining structure is desired that can be applied to buildings of various sizes without increasing construction costs, and without restrictions on the dimensions, specifications, or number of bolts of the embedded plates.

[0008] Here, Patent Document 1 proposes a connection structure for precast concrete strip foundation members, in which the strip foundation is divided into units, and consists of a foundation beam section and a footing section. Specifically, at the end faces of the foundation beam sections facing each other, embedded plates are embedded in two places, upper and lower, with a portion of them exposed, forming relative recesses at the end faces of the foundation beam section and the footing section. The adjacent strip foundation members are installed with a gap between their respective end faces, and a connecting plate is straddled between the embedded plates exposed at both end faces. The connecting plate and the embedded plate are bolted together, and mortar or concrete is filled between the end faces of both strip foundation members and within their respective recesses to connect them to each other. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 9-165756 [Overview of the project] [Problems that the invention aims to solve]

[0010] The connecting structure for precast concrete strip foundation members described in Patent Document 1 also involves bolting together separate embedded plates, each embedded in two locations (upper and lower) of adjacent strip foundation members, via a connecting plate. This structure, like the conventional structure described above where embedded plates are bolted together, has limitations on the dimensions and specifications of the embedded plates and the number of bolts, potentially limiting its application to small-scale buildings.

[0011] This invention has been made in view of the above-mentioned problems, and aims to provide a PCa foundation block joining structure that can be applied to buildings of various sizes without increasing construction costs, without restrictions on the dimensions and specifications of the embedded plate or the number of bolts, and with high joint strength between two PCa foundation blocks. [Means for solving the problem]

[0012] To achieve the above objective, one embodiment of the PCa foundation block joining structure according to the present invention is: A joint structure for reinforced concrete PCa foundation blocks that form the rising portion of the foundation, In the gap between the end faces of the two PCa foundation blocks, upper and lower reinforcing bars protrude from each end face. In the aforementioned gap, the upper and lower reinforcing bars are welded to a common embedded plate, and the two embedded plates are bolted together via a splice plate. The gap is characterized by being sealed with cast-in-place concrete.

[0013] According to this embodiment, upper and lower reinforcing bars protrude from the end faces of two precast concrete (PCa) foundation blocks into the gap between their end faces, and the upper and lower reinforcing bars are welded to a common embedded plate. The two embedded plates are bolted together via a splice plate. As a result, a vertically long embedded plate is applied that spans the upper and lower reinforcing bars constituting the PCa foundation block, eliminating the problem of limitations on the dimensions and specifications of the embedded plate. This makes it applicable to PCa foundations for buildings of various sizes, from small to large. Furthermore, since it does not use mechanical joints that require grout filling, it does not lead to increased construction costs. In addition, the application of a vertically long embedded plate guarantees high shear strength.

[0014] Furthermore, in another embodiment of the PCa foundation block joining structure according to the present invention, The two embedded plates are sandwiched between a pair of splice plates at two locations, upper and lower, and are bolted together with high-strength bolts.

[0015] According to this embodiment, two embedded plates are sandwiched between a pair of splice plates at two locations, above and below them, and bolted together with high-strength bolts such as high-strength hexagonal bolts, thereby forming a joint structure with high joint strength.

[0016] Furthermore, in another embodiment of the PCa foundation block joining structure according to the present invention, Inside the aforementioned PCa foundation block, stirrups are provided that connect the upper and lower reinforcement bars in the longitudinal direction. There are no ribs in the aforementioned gap. The embedded plate is characterized in that it serves as a shear reinforcement member in the gap.

[0017] According to this aspect, instead of having web bars connecting the upper and lower bars vertically in the gap between two PCa foundation blocks, an embedded plate that spans across the upper and lower bars and is long in the vertical direction serves as a shear reinforcement member, thereby forming a joint structure with high shear strength in the gap.

[0018] Also, in another aspect of the joint structure of the PCa foundation block according to the present invention, each of the embedded plates and the splice plates is bolted together by a plurality of high-strength bolts arranged at intervals in the longitudinal direction of the PCa foundation block.

[0019] According to this aspect, the embedded plates and the splice plates are bolted together by a plurality of high-strength bolts arranged at intervals in the longitudinal direction of the PCa foundation block. In other words, since the embedded plate has a plurality of bolt holes at intervals in its lateral (horizontal) direction and is a wide embedded plate that is also long in the lateral direction, it serves as a shear reinforcement member across the entire lateral area. Also, for example, above and below each embedded plate, the embedded plate is bolted to the splice plate by a plurality of (for example, two or three) high-strength bolts, thereby forming a joint structure with even higher joint strength.

[0020] Also, in another aspect of the joint structure of the PCa foundation block according to the present invention, Two of the embedded plates have openings inside the wide surface, and the cast-in-place concrete enters the openings.

[0021] According to this aspect, the embedded plate has an opening inside the wide surface, and the cast-in-place concrete enters the opening. As a result, the cast-in-place concrete body that has entered the opening and hardened serves as a shear key, enhancing the joint strength between the cast-in-place concrete body that closes the gap and the embedded plate.

[0022] Also, in another aspect of the joint structure of the PCa foundation block according to the present invention, The end face of the PCa foundation block has a recess, and the in-situ concrete has penetrated into the recess.

[0023] According to this aspect, a recess (cotter) is provided on the end face of the PCa foundation block, and the in-situ concrete that has penetrated into the recess forms a shear key as the in-situ concrete body that has penetrated and hardened in the recess, and the bonding strength between the PCa foundation block and the in-situ concrete body can be enhanced.

[0024] Also, in another aspect of the joint structure of the PCa foundation block according to the present invention, the PCa foundation block is a laminated structure of a footing and a foundation beam, the upper end bars and the lower end bars forming the foundation beam are welded and joined to the embedded plate, and a gap is provided between the end faces of at least two of the foundation beams.

[0025] According to this aspect, since the PCa foundation block is a laminated structure of a footing and a foundation beam, a PCa foundation with a joint structure having high joint strength can be formed with a footing and a foundation beam. Here, "a gap is provided between the end faces of at least two foundation beams" includes a form in which a gap is provided only between the end faces of two foundation beams and no gap is provided between two footings, and a form in which gaps are provided over the entire area of the end faces of two laminated structures. In the former form, the end faces of the left and right footings can be joined to each other by filling with an adhesive or grout.

Effect of the Invention

[0026] As can be understood from the above description, according to the joint structure of the PCa foundation block of the present invention, without increasing the construction cost, it can be applied to buildings of various sizes without restrictions on the dimensions and specifications of the embedded plate and the number of bolts, and a joint structure of PCa foundation blocks with high joint strength between two PCa foundation blocks can be provided.

Brief Description of the Drawings

[0027] [Figure 1] This is a perspective view of a precast concrete (PCa) foundation block, which forms an example of a joint structure for a precast concrete (PCa) foundation block according to an embodiment, and is a perspective view in which the internal reinforcing bars are visible. [Figure 2] This is a view from the direction arrow II in Figure 1, and is a front view seen from the end face of the PCa foundation block. [Figure 3] This is a perspective view showing two embedded plates bolted together in a gap between the end faces of two precast concrete (PCa) foundation blocks, with the upper and lower reinforcing bars of both plates welded together. The view is transparent, allowing the internal reinforcing bars to be seen. [Figure 4] This is a view from the direction of arrow IV in Figure 3. [Figure 5] This is a perspective view of an example of a joint structure for a precast concrete (PCa) foundation block according to an embodiment, in which the internal reinforcing bars are visible. [Modes for carrying out the invention]

[0028] Hereinafter, an example of the joint structure of a PCa foundation block according to the embodiment will be described with reference to the attached drawings. In this specification and drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant explanations.

[0029] [Joining structure of PCa foundation block according to the embodiment] An example of a PCa foundation block joint structure according to the embodiment will be described with reference to Figures 1 to 5. Here, Figure 1 is a perspective view of a PCa foundation block forming an example of a PCa foundation block joint structure according to the embodiment, and is a perspective view in which the internal reinforcing bars are visible. Figure 2 is a view in direction II of Figure 1, and is a front view seen from the end face of the PCa foundation block. Figure 3 is a perspective view showing two embedded plates bolted together in a gap between the end faces of two PCa foundation blocks, with the upper and lower reinforcing bars of both plates welded together, and is a perspective view in which the internal reinforcing bars are visible. Figure 4 is a view in direction IV of Figure 3. Furthermore, Figure 5 is a perspective view of an example of a PCa foundation block joint structure according to the embodiment, and is a perspective view in which the internal reinforcing bars are visible.

[0030] As shown in Figure 1, the PCa foundation block 30 (precast concrete foundation block) is a laminated structure of a reinforced concrete footing 20 and a foundation beam 10 that forms the rising portion of a foundation such as a strip foundation. The foundation beam 10 has upper reinforcement bars 13 and lower reinforcement bars 14 (both main reinforcement bars) extending in the longitudinal direction, and multiple stirrups 15 equipped with hooks that connect the upper reinforcement bars 13 and lower reinforcement bars 14 in the longitudinal direction.

[0031] On the other hand, the footing 20 has multiple base reinforcements 22, 21 inside that extend in two directions: the longitudinal direction and a direction perpendicular to it.

[0032] In addition, the illustrated example shows that some of the vertically extending anchor bolts 17 are embedded in the foundation beam 10, with their heads protruding upward from the top surface of the foundation beam 10. The heads of these anchor bolts 17 are inserted into bolt holes in the column base plates of a steel column (not shown) and tightened with nuts.

[0033] Although not shown in the diagram, the PCa foundation block may also have a parapet wall of a predetermined height further provided on the top surface of the foundation beam 10.

[0034] The upper reinforcement bars 13 and lower reinforcement bars 14 protrude laterally from the end face 31 of the PCa foundation block 30, forming protruding portions 13a and 14a.

[0035] In these protruding sections 13a and 14a, the center of each reinforcing bar is cut out, and a common steel embedded plate 40 is fitted into the cutouts of both reinforcing bars. The embedded plate 40 and the protruding sections 13a and 14a are then welded together, thereby integrating the embedded plate 40 with the upper reinforcing bar 13 and the lower reinforcing bar 14.

[0036] As clearly shown in Figure 2, the end face 31 of the PCa foundation block 30 is provided with a total of four recesses 32, two on the top and two on the bottom, at the left and right positions of the embedded plate 40.

[0037] Furthermore, the wide surface of the embedded plate 40 is provided with two openings 45 at the top and bottom, and multiple bolt holes 42 (two in the illustrated example) are provided at intervals along the longitudinal direction on both the top and bottom of the wide surface.

[0038] Furthermore, as shown in Figure 2, multiple height-adjusting legs 23 are provided on the underside of the footing 20, allowing the height of the PCa foundation block 30 to be adjusted as desired by adjusting the height-adjusting legs 23.

[0039] As shown in Figure 3, the two PCa foundation blocks 30 are arranged so as to leave a gap 35 of a predetermined width between their two end faces 31. In this gap 35, there are the protruding upper reinforcement bars 13 and lower reinforcement bars 14, respectively, which extend from the two end faces 31, and embedded plates 40 are welded to both protruding bars 13a and 14a.

[0040] Then, a pair of splice plates 50, each having four bolt holes positioned to correspond to the two bolt holes 42 located above and below the two embedded plates 40, sandwich the two embedded plates 40 from above and below. High-strength bolts 60 are inserted through the corresponding bolt holes and tightened, thereby bolting the two embedded plates 40 together via the pair of splice plates 50.

[0041] Here, as shown in Figure 4, one end 41 of the embedded plate 40 is embedded inward from the end face 31 of the PCa foundation block 30, thereby achieving a stronger integration between the PCa foundation block 30 and the embedded plate 40. In other words, in the factory, before pouring the concrete for the PCa foundation block 30, the protruding portions 13a and 14a of the upper reinforcement 13 and lower reinforcement 14 are welded together to the embedded plate 40. Then, the concrete is poured so as to enclose one end 41 of the embedded plate 40, and the PCa foundation block 30 equipped with the embedded plate 40 is manufactured. Consequently, the PCa foundation block 30 equipped with the embedded plate 40 is transported to the site and installed in the predetermined location. The joint shown in Figure 3 is formed simply by bolting it with high-strength bolts 60 via the splice plate 50, eliminating the need for welding work at the site.

[0042] As is clear from Figures 3 and 4, the embedded plate 40 to be applied is long in the vertical direction, spanning the protruding portions 13a and 14a of the upper reinforcement bars 13 and lower reinforcement bars 14, and is also long in the horizontal direction, with multiple bolt holes spaced apart in the longitudinal direction. As such, there are no issues with limitations on the dimensions or specifications of the embedded plate, and it can be applied to PCa foundations of buildings of various sizes, from small to large.

[0043] Furthermore, although there are no stirrups in the gap 35 between the two precast concrete foundation blocks 30, the application of long embedded plates 40 in both the longitudinal and transverse directions allows the embedded plates 40 to act as shear reinforcement members in the gap 35, contributing to the formation of a joint structure with high shear strength.

[0044] Furthermore, since it does not use mechanical joints that require grout filling, it does not create issues such as increased construction costs.

[0045] At the construction site, a formwork (not shown) is installed in the gap 35, cast-in-place concrete is poured into the formwork, and after the concrete hardens, the formwork is removed. As shown in Figure 5, a cast-in-place concrete body 70, comprising a foundation beam section 71 and a footing section 72, is constructed between the two PCa foundation blocks 30, forming a joint structure 100 consisting of the two PCa foundation blocks and the cast-in-place concrete body 70 between them.

[0046] The cast-in-place concrete fills the opening 45 in the embedded plate 40 and hardens, and a portion of this filled-in cast-in-place concrete body 70 acts as a shear key, thereby increasing the joint strength between the cast-in-place concrete body 70 that closes the gap 35 and the embedded plate 40.

[0047] Furthermore, because a portion of the cast-in-place concrete body 70 fits into a plurality of recesses 32 provided on the end face 31 of the PCa foundation block 30, this portion of the cast-in-place concrete body 70 acts as a shear key, thereby increasing the joint strength between the PCa foundation block 30 and the cast-in-place concrete body 70.

[0048] Furthermore, other embodiments may be used in which other components are combined with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of symbols]

[0049] 10: Foundation beam 13: Upper end muscle 13a: Protruding section 14: Lower end muscle 14a: Protruding section 15: Ribs 17: Anchor bolts 20: Footing 21,22: Base muscles 23: Height-adjustable legs 30: PCa foundation block 31: End face 32: Recess 35: Gap 40: Recessed plate 41: One end 42: Bolt holes 45:Aperture 50: Splice plate 60: High-strength bolts 70: Cast-in-place concrete body (cast-in-place concrete) 71:Foundation beam part 72: Footing section 100: Joint structure (Joining structure of precast concrete foundation blocks)

Claims

1. A joint structure for reinforced concrete precast concrete (PCa) foundation blocks that form the rising portion of the foundation, In the gap between the end faces of the two PCa foundation blocks, upper and lower reinforcing bars protrude from each end face. In the gap, the upper and lower reinforcing bars of the two PCa foundation blocks are welded to the embedded plates provided in each PCa foundation block, and the embedded plates of the two PCa foundation blocks are bolted together via splice plates. A joint structure for precast concrete (PCa) foundation blocks, characterized in that the gap is sealed with cast-in-place concrete.

2. The joining structure for a precast concrete foundation block according to claim 1, characterized in that the two embedded plates are sandwiched between a pair of splice plates at two locations, upper and lower, and bolted together with high-strength bolts.

3. Inside the aforementioned precast concrete foundation block, stirrups are provided that connect the upper and lower reinforcement bars in the longitudinal direction. There are no ribs in the aforementioned gap. The PCa foundation block joining structure according to claim 1 or 2, characterized in that the embedded plate serves as a shear reinforcing member in the gap.

4. The PCa foundation block joining structure according to claim 2, characterized in that each of the embedded plates and the splice plates is bolted together by a plurality of high-strength bolts, which are arranged at intervals in the longitudinal direction of the PCa foundation block.

5. The PCa foundation block joining structure according to claim 1 or 2, characterized in that the two embedded plates have openings inside their wide surfaces, and the cast-in-place concrete is filled into these openings.

6. The PCa foundation block joining structure according to claim 1 or 2, characterized in that the end face of the PCa foundation block is provided with a recess, and the cast-in-place concrete is filled into the recess.

7. Each of the two precast concrete foundation blocks is a laminated structure of a footing and a foundation beam, The PCa foundation block joining structure according to claim 1 or 2, characterized in that each of the two PCa foundation blocks forms the foundation beam, and the upper and lower reinforcing bars protruding from the end faces of the foundation beams are welded to the embedded plates provided in each of the PCa foundation blocks, and the gap is provided between the end faces of the two foundation beams.

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