Precast concrete foundation

Abstract

This invention provides a precast concrete foundation that avoids brittle failure of shear cotter by designating the shear cotter's failure mode as a bearing failure type. [Solution] The precast concrete foundation has a structure in which the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10 face each other with a gap G between them, and grout material is filled into the gap G. In the precast concrete foundation, both the first end face 11 and the second end face 12 are provided with a plurality of vertically elongated shear cotters 14 spaced apart in the horizontal direction. Each shear cotter 14 on the first end face 11 and each shear cotter 14 on the second end face 12 face each other.

Description

[Technical Field]

[0001] The present invention relates to a precast concrete foundation. [Background Art]

[0002] Building foundations are required to shorten the construction period and improve the dimensional accuracy of the foundation. In order to meet these requirements, a construction method is applied in which the rising portion of the foundation is manufactured as a concrete foundation block (precast concrete foundation block) in a factory, and this concrete foundation block is transported to a construction site for use in foundation construction. By laying a plurality of concrete foundation blocks transported to the construction site along the extending direction of the foundation, and constructing footings on site below the rising portions formed by the concrete foundation blocks so as to be integrated with the rising portions, the construction period for foundations such as strip foundations can be significantly shortened.

[0003] In precast concrete foundations, adjacent concrete foundation blocks in the extending direction of the foundation are joined to each other by filling grout material into the gap between the blocks. In order to increase the shear strength of the joint formed by the grout material, a structure is applied in which shear cotters are provided on the opposing end faces of both concrete foundation blocks, and the grout filled in the gap between the two end faces is allowed to enter the shear cotters and harden.

[0004] Box-type shear cotters are generally used for these shear cotters, but since the area bearing shear force is generally small, there are problems in terms of shear strength. Patent Document 1 proposes a precast concrete foundation material that solves this problem. The shear cotter provided on the end face of this precast concrete foundation material is formed into a shape in which a plurality of protrusions of a constant height are arranged vertically at equal intervals in the lateral direction, thereby forming a corrugated shear cotter in which peaks and valleys of a predetermined height are alternately formed. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-25667 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In the precast concrete foundation material described in Patent Document 1, the corrugated shear cotter has a horizontally elongated shape that extends laterally, so the failure mode in the shear cotter becomes shear failure type, and there is a risk that the shear cotter will fracture brittlely without deformation.

[0007] This invention has been made in view of the above problems, and aims to provide a precast concrete foundation that can avoid brittle failure in shear cotter by setting the failure mode in shear cotter to a bearing failure type. [Means for solving the problem]

[0008] To achieve the above objectives, embodiments of the present invention are provided. A precast concrete foundation that supports the superstructure of a building, wherein, among a plurality of precast concrete foundation blocks, the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block face each other with a gap between them, and the gap is filled with grout material, and the foundation supports the superstructure of a building. Both the first and second end faces are provided with a plurality of vertically elongated shear cotters spaced apart in the lateral direction. The present invention provides a precast concrete foundation characterized in that each of the shear cotters on the first end face and each of the shear cotters on the second end face face opposite each other.

[0009] According to this embodiment, in the precast concrete foundation, the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block face each other with a gap between them, and grout material is filled into the gap. Multiple vertically elongated shear cotters are provided on both the first and second end faces at intervals in the horizontal direction, with each shear cotter on the first end face facing each other on the second end face. With this configuration, multiple vertically elongated shear cotters can be evenly and comprehensively distributed on the first end face of one adjacent foundation concrete block and the second end face of the other concrete block. This ensures the load-bearing capacity of the joint provided by the grout material filled between the first and second end faces.

[0010] Furthermore, vertically elongated shear cotters include shear cotters whose vertical dimension is larger than their horizontal dimension, or shear cotters whose vertical dimension is more than twice, three times, or four times the horizontal dimension. In this way, the vertically elongated shape of the shear cotter improves the vertical shear strength of the shear cotter, and reduces the area of ​​the bearing surface of the shear cotter compared to cases where it does not have a vertical shape. The bearing surface is, for example, the interface between the grout material and the precast concrete (PCa) portion of the concrete foundation block at the lower end of the shear cotter. This makes it possible to provide a precast concrete foundation that avoids brittle failure of the shear cotter by making the failure mode of the grout material or PCa portion in the shear cotter a bearing failure type.

[0011] Another embodiment of the present invention is, in the aforementioned precast concrete foundation, The plurality of shear cotters are characterized in that they are arranged with intervals between them in the horizontal and vertical directions.

[0012] According to this embodiment, multiple vertically elongated shear cotters can be evenly and uniformly arranged on the first end face of one adjacent foundation concrete block and the second end face of the other concrete foundation block. This improves the load-bearing capacity of the joint formed by the grout material filled between the first and second end faces.

[0013] Yet another embodiment of the present invention is, in the aforementioned precast concrete foundation, The plurality of shear cotters are characterized by being arranged at equal intervals in the vertical direction.

[0014] According to this embodiment, multiple shear cotters can be evenly arranged in the longitudinal direction where the load is applied, on the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block. This allows each shear cotter to evenly receive the longitudinal load, improving the shear strength of the grout material or PCa portion in the multiple shear cotters. Furthermore, it facilitates strength calculations for the shear cotters.

[0015] Yet another embodiment of the present invention is, in the aforementioned precast concrete foundation, Both the first and second end faces are provided with a C-shaped fitting for engaging one end or the other end of an H-shaped fitting, a plurality of shear cotters arranged on both sides of the C-shaped fitting, and a plurality of shear cotters arranged at equal intervals in the lateral direction below the C-shaped fitting. The present invention is characterized by having a configuration in which one end and the other end of the H-shaped metal fitting are engaged with the C-shaped metal fitting on the first end face and the C-shaped metal fitting on the second end face, respectively.

[0016] According to this embodiment, the C-shaped metal fittings of one adjacent concrete foundation block and the C-shaped metal fitting of the other adjacent concrete foundation block are connected via the H-shaped metal fittings by engaging one end of the H-shaped metal fitting with the other end of the H-shaped metal fitting. Furthermore, each C-shaped metal fitting is connected, for example, to the upper reinforcement embedded in each concrete foundation block and extending in the direction of extension of the precast concrete foundation. Therefore, the upper reinforcement of one adjacent concrete foundation block and the upper reinforcement of the other concrete foundation block can be connected via the C-shaped metal fittings of each concrete foundation block and the H-shaped metal fittings engaged with them.

[0017] Furthermore, on the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block, multiple shear cotters are placed on both sides of the C-shaped metal fitting, and multiple shear cotters are placed at equal intervals horizontally on the lower side of the C-shaped metal fitting. In this way, by placing multiple vertically elongated shear cotters across the entire first and second end faces of the opposing first and second end faces of the adjacent concrete foundation blocks, including the narrow space on both sides of the C-shaped metal fitting, the load-bearing capacity of the joint filled with grout can be ensured.

[0018] Yet another embodiment of the present invention is, in the aforementioned precast concrete foundation, The plurality of shear cotters are characterized in that one shear cotter is arranged vertically with an interval between them horizontally.

[0019] According to this embodiment, the vertical dimension of the shear cotter can be made sufficiently larger than the horizontal dimension. This improves the vertical shear strength of the grout material or PCa portion in the shear cotter, making it possible to more reliably make the failure mode of the shear cotter a bearing failure type, and thus more reliably avoiding brittle failure in the shear cotter.

[0020] Yet another embodiment of the present invention is, in the aforementioned precast concrete foundation, Each of the first end face and the second end face is provided with a C-shaped metal fitting that engages one end or the other end of an H-shaped metal fitting, a plurality of said shear cotters arranged on both sides of said C-shaped metal fitting, and said shear cotter arranged on the lower side of said C-shaped metal fitting, characterized in that said C-shaped metal fitting on said first end face and said C-shaped metal fitting on said second end face are configured to have said one end and said other end of said H-shaped metal fitting engaged thereto, respectively.

[0021] According to the present embodiment, by engaging one end and the other end of the H-shaped metal fitting with the C-shaped metal fitting of one mutually adjacent concrete foundation block and the C-shaped metal fitting of the other mutually adjacent concrete foundation block, respectively, these C-shaped metal fittings are connected via the H-shaped metal fitting. Further, each C-shaped metal fitting is, for example, embedded in each concrete foundation block and connected to an upper reinforcing bar extending in the extending direction of the precast concrete foundation. Therefore, the upper reinforcing bar of one mutually adjacent concrete foundation block and the upper reinforcing bar of the other mutually adjacent concrete foundation block can be connected via the C-shaped metal fittings of each concrete foundation block and the H-shaped metal fitting engaged therewith.

[0022] Further, on both the first end face of one mutually adjacent concrete foundation block and the second end face of the other mutually adjacent concrete foundation block, a plurality of shear cotters are arranged on both sides of the C-shaped metal fitting, and a shear cotter is arranged on the lower side of the C-shaped metal fitting. In this way, by arranging a plurality of vertically elongated shear cotters over the entire first end face and second end face including the narrow spaces on both sides of the C-shaped metal fitting on the opposing first end face and second end face of mutually adjacent concrete foundation blocks, the yield strength of the joint filled with grout material can be ensured.

[0023] Still another embodiment of the present invention is the precast concrete foundation described above, characterized in that the shear cotter is a concave portion or a convex portion.

[0024] According to this embodiment, when the shear cotter is a recess, the grout material filled in the gap between the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block flows into the shear cotter between the first and second end faces and hardens. This ensures the load-bearing capacity of the joint provided by the grout material filled between the first and second end faces.

[0025] Furthermore, when the shear cotter has a convex shape, grout material is filled into the gap between the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block. The grout material then flows into the space around the shear cotter and hardens to fill that space. This ensures the load-bearing capacity of the joint due to the grout material filled into the gap between the first and second end faces. Also, because the shear cotter has a convex shape, compared to when the shear cotter is concave, the grout material can be easily flowed and filled into the gap between the first and second end faces along the elongated shear cotter.

[0026] Yet another embodiment of the present invention is, in the aforementioned precast concrete foundation, The shear cotter is characterized by having a rectangular parallelepiped shape.

[0027] According to this embodiment, a rectangular interface along the horizontal plane is formed between the grout material and the PCa portion of the concrete foundation block at the lower end of the shear cotter. As a result, the precast concrete foundation can evenly receive the bearing pressure acting in the vertical direction on each concrete foundation block at the rectangular interface of the shear cotter.

[0028] As a result, bearing failure can occur in the grout material or PCa portion at or near the bearing surface of the shear cotter without causing shear failure along the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block. This avoids brittle failure in the shear cotter. Furthermore, the rectangular parallelepiped shape of the shear cotter makes it easier to arrange and calculate the strength of the shear cotter compared to other shapes.

[0029] Yet another embodiment of the present invention is, in the aforementioned precast concrete foundation, The aforementioned shear cotter is characterized by having a truncated pyramidal shape.

[0030] According to this embodiment, at the lower end of the shear cotter, a trapezoidal bearing surface inclined with respect to the horizontal direction is formed between the grout material and the PCa portion of the concrete foundation block. As a result, the precast concrete foundation can evenly receive the bearing pressure acting in the vertical direction on each concrete foundation block at the trapezoidal bearing surface of the shear cotter.

[0031] As a result, bearing failure can occur in the grout material or PCa portion at or near the lower end of the shear cotter without causing shear failure along the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block. This avoids brittle failure in the shear cotter. Furthermore, compared to cases where the shear cotter has a rectangular parallelepiped shape, it is possible to facilitate mold removal during the molding of the concrete foundation block and improve the productivity of the concrete foundation block. In addition, the truncated pyramidal shape of the shear cotter makes it easier to arrange the shear cotter and calculate its strength compared to other shapes. [Effects of the Invention]

[0032] As can be understood from the above description, according to each of the above embodiments of the present invention, it is possible to provide a precast concrete foundation that avoids brittle failure in the shear cotter by setting the failure mode in the shear cotter to a bearing failure type. [Brief explanation of the drawing]

[0033] [Figure 1] This is a side view of an example of a precast concrete foundation according to the embodiment. [Figure 2] Figure 1 shows the end view, top view, and cross-sectional view of the concrete foundation block. [Figure 3] Figure 1 shows a top view and a cross-sectional view of the joint in the concrete foundation block. [Figure 4] Figure 2 shows a front view and a cross-sectional view of the shear cotter provided on the first end face. [Figure 5] Figure 2 shows an end view and a cross-sectional view of a modified concrete foundation block. [Figure 6] Figure 5 is a cross-sectional view of the joint in the concrete foundation block. [Figure 7] Figure 2 is an end view showing a modified example of the concrete foundation block. [Figure 8] Figure 2 shows an end view and a cross-sectional view of a modified concrete foundation block. [Modes for carrying out the invention]

[0034] Hereinafter, embodiments of the precast concrete foundation according to the present invention 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.

[0035] Figure 1 is a side view showing an example of a precast concrete foundation 100 according to this embodiment. The precast concrete foundation 100 of this embodiment is composed of a plurality of precast concrete foundation blocks 10 that form the rising portion of a foundation such as a strip foundation, and supports the superstructure of a building.

[0036] The concrete foundation block 10 has multiple upper and lower reinforcement bars (not shown in the illustration), multiple stirrups, and multiple web reinforcement bars. The upper and lower reinforcement bars extend in the direction of extension of the foundation. The stirrups connect the upper and lower reinforcement bars vertically and are arranged at a predetermined pitch in the direction of extension. The web reinforcement bars are located between the multiple upper and lower reinforcement bars and extend in the direction of extension.

[0037] The concrete foundation blocks 10 are manufactured in a factory and transported to the site, where they are arranged, for example, in the direction of extension of the foundation along the exterior wall of the building. As a result, the first end face 11 of one precast concrete foundation 100 and the second end face 12 of the other concrete foundation block 10 face each other with a gap G between them. Furthermore, grout material 50 is filled into the gap G between the first end face 11 and the second end face 12 to form a joint 60.

[0038] In this way, a precast concrete foundation 100 is formed by arranging multiple concrete foundation blocks 10 in the direction of extension of the foundation and joining the first end face 11 and the second end face 12 of mutually adjacent concrete foundation blocks 10 via a joint 60. Furthermore, a reinforced concrete footing 70, shown by a dashed line, is constructed on-site so as to be integrated with the lower end 13 of each concrete foundation block 10 that constitutes the precast concrete foundation 100, thereby forming a foundation such as a strip foundation.

[0039] Figure 2 shows an end view of the first end face 11 at one end of the concrete foundation block 10 that constitutes the precast concrete foundation 100 in Figure 1, a top view of that end seen from above, and a cross-sectional view of that end taken along line AA in the end view. The second end face 12 at the other end of the concrete foundation block 10 has the same configuration as the first end face 11 shown in Figure 2, so the reference numeral for the second end face 12 is added to the reference numeral for the first end face 11 in Figure 2, and the second end face 12 is omitted from the illustration.

[0040] As shown in Figure 2, multiple vertically elongated shear cotters 14 are provided at intervals in the horizontal direction on both the first end face 11 and the second end face 12 of the concrete foundation block 10. In the illustrated example, the multiple shear cotters 14 are arranged at intervals in both the horizontal and vertical directions. Note that on the first end face 11 and the second end face 12, the vertical direction is generally parallel to the vertical direction, and the horizontal direction is generally parallel to the horizontal direction.

[0041] Furthermore, in the example shown in Figure 2, each shear cotter 14 is a recess provided on the first end face 11 and the second end face 12. Each shear cotter 14 also has a truncated pyramidal shape. Each shear cotter 14 has the same shape and dimensions, except for manufacturing tolerances.

[0042] Furthermore, in the example shown in Figure 2, the vertically elongated shear cotter 14 has a vertical dimension that is more than twice its horizontal dimension. Note that a vertically elongated shear cotter 14 means that the vertical dimension of the shear cotter 14 is larger than its horizontal dimension, and this includes cases where the vertical dimension is more than three times, four times, or five times the horizontal dimension.

[0043] Furthermore, in the example shown in Figure 2, the multiple shear cotters 14 are arranged at equal intervals in the vertical direction. Specifically, shear cotters 14 adjacent to each other in the vertical direction are spaced apart in the vertical direction so that a precast concrete (PCa) portion having approximately the same cross-sectional shape and dimensions as each shear cotter 14 is formed between them.

[0044] Furthermore, in the example shown in Figure 2, C-shaped metal fittings 15 are provided on both the first end face 11 and the second end face 12 of the concrete foundation block 10. The C-shaped metal fittings 15 are connected to the ends of the upper reinforcement bars arranged inside each concrete foundation block 10. The C-shaped metal fittings 15 have a generally C-shaped concave shape when viewed from above the concrete foundation block 10 and are installed at the lower ends of the grooves 16 provided on the first end face 11 and the second end face 12. The grooves 16 on the first end face 11 and the second end face 12 extend vertically downward from the top surface 17 of the concrete foundation block 10 and open on the first end face 11 and the second end face 12, respectively.

[0045] Furthermore, in the example shown in Figure 2, the first end face 11 and the second end face 12 of the concrete foundation block 10 are provided with a plurality of shear cotters 14 positioned on both sides of the C-shaped metal fitting 15, and a plurality of shear cotters 14 positioned at equal intervals in the horizontal direction below the C-shaped metal fitting 15. In the illustrated example, one shear cotter 14 is provided on each side of the C-shaped metal fitting 15, but two or more shear cotters 14 may be provided on the left and right sides of the C-shaped metal fitting 15. Also, in the illustrated example, a total of 12 shear cotters 14 are provided below the C-shaped metal fitting 15, three in the vertical direction and four in the horizontal direction, but the number of shear cotters 14 in the vertical and horizontal directions is not particularly limited.

[0046] Figure 3(A) is a top view of a joint 60 provided between adjacent concrete foundation blocks 10 in the precast concrete foundation 100 of Figure 1. Figure 3(B) is a cross-sectional view of the joint 60 shown in the top view of (A), cut along the line BB. Note that in Figure 3, the grout material 50 that is filled into the gap G between the first end face 11 of one concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10, which are adjacent in the extension direction of the foundation, is not shown.

[0047] As shown in Figures 3(A) and (B), in the case of adjacent concrete foundation blocks 10, each shear cotter 14 provided on one first end face 11 and each shear cotter 14 provided on the other second end face 12 are facing each other in the direction of extension. As a result, when grout material 50 is filled into the gap G between the first end face 11 and the second end face 12, the grout material 50 flows from the gap G into each shear cotter 14 on the first end face 11 and the second end face 12 and hardens, joining the first end face 11 and the second end face 12 to form a joint 60.

[0048] Furthermore, before filling the gap G with grout material 50, a C-shaped metal fitting 15 provided on the first end face 11 of one concrete foundation block 10 and a C-shaped metal fitting 15 provided on the second end face 12 of the other concrete foundation block 10 are connected via an H-shaped metal fitting 20. Specifically, as shown in Figure 3(A), with the C-shaped metal fitting 15 on the first end face 11 and the C-shaped metal fitting 15 on the second end face 12 facing each other, one end of the H-shaped metal fitting 20 is engaged with the C-shaped metal fitting 15 on the first end face 11, and the other end of the H-shaped metal fitting 20 is engaged with the C-shaped metal fitting 15 on the second end face 12.

[0049] As a result, the upper reinforcement bars of one concrete foundation block 10 adjacent to the other concrete foundation block 10 in the direction of extension of the foundation are connected via a pair of C-shaped metal fittings 15 and H-shaped metal fittings 20. Subsequently, grout material 50 is filled into the grooves 16 of each concrete foundation block 10 and the gap G between the first end face 11 and the second end face 12, forming a joint 60.

[0050] The operation of the precast concrete foundation 100 in this embodiment will be explained below with reference to Figure 4.

[0051] Figure 4(A) shows a front view, a vertical cross-sectional view, and a cross-sectional view showing the area of ​​the bearing surface 14a of a plurality of vertically elongated shear cotters 14 provided on the first end face 11 and the second end face 12 of the concrete foundation block 10 shown in Figure 2. Figure 4(B) shows a front view, a vertical cross-sectional view, and a cross-sectional view showing the area of ​​the bearing surface SC1a of comparative example 1 shear cotter SC1, which is different from the shear cotter 14 of this embodiment. Figure 4(C) shows a front view, a vertical cross-sectional view, and a cross-sectional view showing the area of ​​the bearing surface SC2a of comparative example 2 shear cotter SC2, which is different from the shear cotter 14 of this embodiment.

[0052] As described above, the precast concrete foundation 100 of this embodiment includes a plurality of precast concrete foundation blocks 10. The precast concrete foundation 100 has a configuration in which the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10 face each other with a gap G between them, and the gap G is filled with grout material 50. With this configuration, the precast concrete foundation 100 supports the superstructure of the building. In this precast concrete foundation 100, a plurality of vertically elongated shear cotters 14 are provided at horizontal intervals on both the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10. Furthermore, each shear cotter 14 on the first end face 11 faces each shear cotter 14 on the second end face 12.

[0053] This configuration allows multiple vertically elongated shear cotters 14 to be evenly and comprehensively placed on the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10 of the precast concrete foundation 100. This ensures the load-bearing capacity of the joint 60 formed by the grout material 50 filled between the first end face 11 and the second end face 12. Furthermore, as shown in Figure 4(A), the vertically elongated shape of the shear cotters 14 improves the vertical shear strength of the grout material 50 within the shear cotters 14.

[0054] Furthermore, Figure 4(A) shows the area of ​​the bearing surface 14a in the vertically elongated shear cotter 14. Also, Figure 4(B) shows the area of ​​the bearing surface SC1a in the shear cotter SC1 of Comparative Example 1, which has the same vertical and horizontal dimensions. Furthermore, Figure 4(C) shows the area of ​​the bearing surface SC2a in the horizontally elongated shear cotter SC2, which has a horizontal dimension greater than its vertical dimension. As shown in these figures, the area of ​​the bearing surface 14a in the vertically elongated shear cotter 14 of this embodiment is smaller than the areas of the bearing surfaces SC1a and SC2a in the shear cotters SC1 and SC2 of Comparative Examples 1 and 2, which are not vertically elongated.

[0055] As a result, in the shear cotter 14 of this embodiment, bearing failure occurs in the PCa portion or grout material 50 at or near the bearing surface 14a of the shear cotter 14 before shear failure occurs in the PCa portion or grout material 50 of the grout material 50 or the PCa portion of the concrete foundation block 10. This makes it possible to provide a precast concrete foundation 100 in which the failure mode of the PCa portion or grout material 50 in the shear cotter 14 is bearing failure type, thereby avoiding brittle failure of the PCa portion or grout material 50.

[0056] In contrast, in Comparative Examples 1 and 2, the shear cotters SC1 and SC2, which are not vertically elongated, have a larger bearing surface area SC1a and SC2a than the bearing surface area 14a in the vertically elongated shear cotter 14 of this embodiment. As a result, in the shear cotters SC1 and SC2 of Comparative Examples 1 and 2, shear failure of the PCa portion or grout material 50 occurs before bearing failure of the PCa portion or grout material 50 near the bearing surfaces SC1a and SC2a. That is, in the shear cotters SC1 and SC2 of Comparative Examples 1 and 2, the failure mode of the PCa portion or grout material 50 becomes shear failure type, and there is a risk of brittle failure occurring in the PCa portion or grout material 50.

[0057] Furthermore, in the precast concrete foundation 100 of this embodiment, the multiple shear cotters 14 are arranged with intervals between them in the horizontal and vertical directions.

[0058] This configuration allows multiple vertically elongated shear cotters 14 to be evenly and uniformly arranged on the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10. This improves the load-bearing capacity of the joint 60 formed by the grout material 50 filling the gap G between the first end face 11 and the second end face 12.

[0059] Furthermore, in the precast concrete foundation 100 of this embodiment, the multiple shear cotters 14 are arranged at equal intervals in the vertical direction.

[0060] This configuration allows multiple shear cotters 14 to be evenly distributed in the longitudinal direction where the load is applied, on the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10. As a result, each shear cotter 14 can evenly receive the longitudinal load, improving the shear strength of the multiple shear cotters 14. Furthermore, it simplifies the strength calculation of the shear cotters 14.

[0061] Furthermore, in the precast concrete foundation 100 of this embodiment, both the first end face 11 and the second end face 12 are provided with a C-shaped metal fitting 15 for engaging one end or the other end of an H-shaped metal fitting 20. In addition, both the first end face 11 and the second end face 12 are provided with a plurality of shear cotters 14 arranged on both sides of the C-shaped metal fitting 15, and a plurality of shear cotters 14 arranged at equal intervals in the lateral direction below the C-shaped metal fitting 15. The precast concrete foundation 100 has a configuration in which one end and the other end of an H-shaped metal fitting 20 are engaged with the C-shaped metal fitting 15 of the first end face 11 and the C-shaped metal fitting 15 of the second end face 12, respectively.

[0062] With this configuration, one end of an H-shaped metal fitting 20 can be engaged with the C-shaped metal fitting 15 of one adjacent concrete foundation block 10 and the C-shaped metal fitting 15 of the other concrete foundation block 10, respectively, and these C-shaped metal fittings 15 can be connected via the H-shaped metal fitting 20. In addition, each C-shaped metal fitting 15 is connected, for example, to the upper reinforcement embedded in each concrete foundation block 10 and extending in the direction of extension of the precast concrete foundation 100. Therefore, the upper reinforcement of one adjacent concrete foundation block 10 and the upper reinforcement of the other concrete foundation block 10 can be connected via the C-shaped metal fitting 15 of each concrete foundation block 10 and the H-shaped metal fitting 20 engaged with them.

[0063] Furthermore, on both the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10, multiple shear cotters 14 are placed on both sides of the C-shaped metal fitting 15. Also, on both the first end face 11 and the second end face 12, multiple shear cotters 14 are placed horizontally at equal intervals below the C-shaped metal fitting 15. In this way, on the opposing first end face 11 and second end face 12 of adjacent concrete foundation blocks 10, multiple vertically elongated shear cotters 14 can be placed over the entire first end face 11 and second end face 12, including the narrow space on both sides of the C-shaped metal fitting 15. Therefore, the load-bearing capacity of the joint 60 formed by filling the gap G between the first end face 11 and the second end face 12 with grout material 50 can be ensured.

[0064] Furthermore, in the precast concrete foundation 100 of this embodiment, the shear cotter 14 is a recess.

[0065] In this configuration, the grout material 50 filled in the gap G between the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10 flows into the shear cotter 14 of the first end face 11 and the second end face 12 and hardens. This ensures that the load-bearing capacity of the joint 60 is secured by the grout material 50 filled in the gap G between the first end face 11 and the second end face 12.

[0066] Furthermore, in the precast concrete foundation 100 of this embodiment, the shear cotter 14 has a truncated pyramidal shape.

[0067] This configuration creates a trapezoidal bearing surface 14a that is slightly inclined horizontally between the grout material 50 and the PCa portion of the concrete foundation block 10 at the lower end of the shear cotter 14. As a result, the precast concrete foundation 100 can evenly receive the vertical bearing pressure acting on each concrete foundation block 10 at the trapezoidal bearing surface 14a of the shear cotter 14.

[0068] As a result, bearing failure occurs at or near the bearing surface 14a of the shear cotter 14 without causing shear failure along the first end face 11 of one adjacent concrete foundation block 10 and the second end face 12 of the other concrete foundation block 10. This avoids brittle failure of the PCa portion or grout material 50 at the bearing surface 14a. Furthermore, compared to the case where the shear cotter 14 has a rectangular parallelepiped shape, it is possible to make the mold removal during the molding of the concrete foundation block 10 easier, thereby improving the productivity of the concrete foundation block 10. In addition, the truncated pyramidal shape of the shear cotter 14 makes it easier to arrange the shear cotter 14 and calculate its strength compared to other shapes.

[0069] As described above, according to this embodiment, a precast concrete foundation 100 can be provided in which the failure mode of the shear cotter 14 is set to a bearing failure type, thereby avoiding brittle failure of the shear cotter 14. It should be noted that the precast concrete foundation according to the present invention is not limited to the embodiments described above. Hereinafter, modifications of the precast concrete foundation 100 according to the above embodiment will be described.

[0070] [Example 1] Figure 5 is an end view showing a modified example 1 of the concrete foundation block 10 constituting the precast concrete foundation 100 according to the above embodiment, and a cross-sectional view obtained by cutting the concrete foundation block 10A according to modified example 1 in a cross section along the CC line shown in the end view. Figure 6 is a cross-sectional view of the joint 60A in the precast concrete foundation equipped with the concrete foundation block 10A of Figure 5. Note that in Figure 6, the grout material 50 that is filled into the gap G1 between the first end face 11 of one concrete foundation block 10A and the second end face 12 of the other concrete foundation block 10A, which are adjacent in the extension direction of the foundation, is not shown.

[0071] In this modified precast concrete foundation, the first end face 11 of one adjacent concrete foundation block 10A and the second end face 12 of the other concrete foundation block 10A have multiple elongated shear cotters 14A as protrusions. The other configurations of the precast concrete foundation in this modified version are the same as those of the precast concrete foundation 100 according to the above embodiment. Therefore, in the precast concrete foundation of this modified version, the same reference numerals are used for parts that are the same as those of the precast concrete foundation 100 in the above embodiment, and their description is omitted.

[0072] In this way, because the shear cotter 14A is a convex portion, the grout material 50 filled in the gap G1 between the first end face 11 and the second end face 12 of the adjacent concrete foundation block 10A shown in Figure 6 hardens to fill the space around the shear cotter 14A. This ensures the load-bearing capacity of the joint 60A formed by the grout material 50 filled in the gap G1 between the first end face 11 and the second end face 12.

[0073] Furthermore, the shear cotter 14A is a protrusion provided on the first end face 11 and the second end face 12 of the mutually adjacent concrete foundation block 10. Therefore, compared to the case where the shear cotter 14 is a recess, it becomes possible to easily fill the gap G between the first end face 11 and the second end face 12 of the mutually adjacent concrete foundation block 10 with grout material 50 along the vertically elongated shear cotter 14A.

[0074] Furthermore, the shear cotter 14A in this modified example is elongated vertically, similar to the shear cotter 14 in the previously described embodiment. As a result, the area of ​​the bearing surface 14a of the shear cotter 14A is reduced, and bearing failure occurs in the shear cotter 14A or the grout material 50 at or near the bearing surface 14a of the shear cotter 14A before shear failure occurs in the grout material 50 or the shear cotter 14A. Therefore, in this modified example as well, the failure mode in the shear cotter 14A is set to bearing failure type, and a precast concrete foundation is provided that can avoid brittle failure in the shear cotter 14A.

[0075] [Modifications 2 and 3] Figures 7(A) and 7(B) are end views showing modified examples 2 and 3 of the concrete foundation block 10 that constitute the precast concrete foundation 100 according to the above embodiment, respectively.

[0076] In the concrete foundation block 10B according to Modification 2 shown in Figure 7(A), the multiple shear cotters 14B, 14C are arranged with one shear cotter 14B, 14C in the vertical direction and one shear cotter 14B, 14C spaced apart in the horizontal direction. Also, the concrete foundation block 10C according to Modification 3 shown in Figure 7(B) does not have C-shaped metal fittings 15 and grooves 16 on the first end face 11 and the second end face 12. The other configurations of the concrete foundation blocks 10B, 10C according to Modifications 2 and 3 are the same as those of the concrete foundation block 10 according to the above embodiment, so the same reference numerals are used for the same parts and their description is omitted.

[0077] In the precast concrete foundation equipped with concrete foundation block 10B according to the modified example 2 shown in Figure 7(A), one shear cotter 14B, 14C is arranged vertically with a gap between them horizontally. Therefore, the vertical dimension of the shear cotters 14B, 14C can be made sufficiently larger than the horizontal dimension. This improves the vertical shear strength of the PCa portion or grout material 50 in the shear cotters 14B, 14C, making it possible to more reliably make the failure mode of the shear cotters 14B, 14C a bearing failure type. Thus, brittle failure of the shear cotters 14B, 14C can be more reliably avoided.

[0078] Furthermore, in the precast concrete foundation equipped with concrete foundation blocks 10B of Modification 2, C-shaped metal fittings 15 are provided on both the first end face 11 and the second end face 12 of adjacent concrete foundation blocks 10B to engage one end or the other end of an H-shaped metal fitting 20. In addition, multiple shear cotters 14B are provided on both sides of the C-shaped metal fitting 15, and a shear cotter 14C is provided below the C-shaped metal fitting 15. The precast concrete foundation of Modification 2 has a configuration in which one end and the other end of an H-shaped metal fitting 20 are engaged with the C-shaped metal fitting 15 on the first end face 11 and the C-shaped metal fitting 15 on the second end face 12, respectively.

[0079] This configuration allows one end of an H-shaped metal fitting 20 to engage with the C-shaped metal fitting 15 of one adjacent concrete foundation block 10B and the C-shaped metal fitting 15 of the other concrete foundation block 10B, respectively. This connects the C-shaped metal fittings 15 via the H-shaped metal fitting 20. Furthermore, each C-shaped metal fitting 15 is connected, for example, to the upper reinforcement embedded in each concrete foundation block 10B and extending in the direction of the extension of the precast concrete foundation. Therefore, the upper reinforcement of one adjacent concrete foundation block 10B and the upper reinforcement of the other concrete foundation block 10B can be connected via the C-shaped metal fitting 15 of each concrete foundation block 10 and the H-shaped metal fitting 20 engaged with them.

[0080] Furthermore, on the first end face 11 of one adjacent concrete foundation block 10B and the second end face 12 of the other concrete foundation block 10B, multiple shear cotters 14B are placed on both sides of the C-shaped metal fitting 15. In addition, on both the first end face 11 and the second end face 12, a shear cotter 14C is placed below the C-shaped metal fitting 15. In this way, on the opposing first end face 11 and second end face 12 of the adjacent concrete foundation blocks 10B, multiple vertically elongated shear cotters 14B, 14C can be placed over the entire first end face 11 and second end face 12, including the narrow space on both sides of the C-shaped metal fitting 15. This ensures the load-bearing capacity of the joint where the grout material 50 is filled in the gap G between the first end face 11 and the second end face 12.

[0081] Furthermore, the concrete foundation block 10C according to Modification 3 shown in Figure 7(B) does not have C-shaped metal fittings 15 and grooves 16 on the first end face 11 and the second end face 12, so the shear cotters 14 can be arranged more uniformly across the entire first end face 11 and the second end face 12. Therefore, in Modifications 2 and 3 as well, it is possible to provide a precast concrete foundation that avoids brittle failure in the shear cotters 14B, 14C, and 14 by setting the failure mode of the shear cotters 14B, 14C, and 14 to be bearing failure type.

[0082] [Differentiation Example 4] Figure 8 shows an end view of a modified concrete foundation block 10 that constitutes the precast concrete foundation 100 according to the above embodiment, and a cross-sectional view of the concrete foundation block 10D according to modified concrete foundation block 4, cut along the line DD shown in the end view. In Figure 8, the cross-sectional view when the shear cotters 14D provided on the first end face 11 and the second end face 12 of the concrete foundation block 10D are recessed and the cross-sectional view when they are convex are shown side by side.

[0083] In the precast concrete foundation according to Modification 4 shown in Figure 8, the shear cotters 14D provided on the first end face 11 and the second end face 12 of the concrete foundation block 10D have a rectangular parallelepiped shape. The other components of the concrete foundation block 10D according to Modification 4 are the same as those of the concrete foundation block 10 according to the above embodiment, so the same reference numerals are used for the same parts and their description is omitted.

[0084] According to this embodiment, a rectangular bearing surface 14a is formed horizontally at the lower end of the shear cotter 14D between the grout material 50 and the PCa portion of the concrete foundation block 10D. As a result, the precast concrete foundation can evenly receive the vertical bearing pressure acting on each concrete foundation block 10D at the rectangular bearing surface 14a of the shear cotter 14D.

[0085] As a result, bearing failure can occur in the PCa portion or grout material 50 at or near the lower end of the shear cotter 14D without causing shear failure along the first end face 11 and second end face 12 of the mutually adjacent concrete foundation block 10D. This avoids brittle failure in the shear cotter 14D. Furthermore, because the shear cotter 14D has a rectangular parallelepiped shape, the placement and strength calculations of the shear cotter 14 can be made easier compared to other shapes.

[0086] Therefore, in the modified example 4 as well, by setting the failure mode in the shear cotter 14D to a bearing failure type, it is possible to provide a precast concrete foundation that can avoid brittle failure in the shear cotter 14D.

[0087] Preferred embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above. Various modifications, substitutions, etc., can be applied to the embodiments described above without departing from the scope of the present invention. Furthermore, each of the features described with reference to the embodiments described above may be combined as appropriate, as long as they do not contradict the technical invention. [Explanation of symbols]

[0088] 10 Concrete foundation blocks 10A Concrete foundation block 10B Concrete foundation block 10C Concrete Foundation Block 10D Concrete Foundation Block 11 First end surface 12 Second end face 14 Sheer Cotter 14A Shear Cotter 14B Sheer Cotter 14C Shear Cotter 14D Shear Cotter 15 C type hardware 20 H-shaped metal fittings 50 Grout material 100 Precast concrete foundation G Gap G1 Gap

Claims

1. A precast concrete foundation that supports the superstructure of a building, wherein, among a plurality of precast concrete foundation blocks, the first end face of one adjacent concrete foundation block and the second end face of the other concrete foundation block face each other with a gap between them, and the gap is filled with grout material, and the foundation supports the superstructure of a building. Both the first and second end faces are provided with a plurality of vertically elongated shear cotters spaced apart in the lateral direction. A precast concrete foundation characterized in that each of the shear cotters on the first end face and each of the shear cotters on the second end face face opposite each other.

2. The plurality of shear cotters are characterized in that they are arranged with intervals between them in the horizontal and vertical directions. The precast concrete foundation according to claim 1.

3. The plurality of shear cotters are characterized in that they are arranged at equal intervals in the vertical direction. The precast concrete foundation according to claim 2.

4. Both the first and second end faces are provided with a C-shaped fitting for engaging one end or the other end of an H-shaped fitting, a plurality of shear cotters arranged on both sides of the C-shaped fitting, and a plurality of shear cotters arranged at equal intervals in the lateral direction below the C-shaped fitting. The H-shaped metal fitting is characterized in that one end and the other end of the H-shaped metal fitting are engaged with the C-shaped metal fitting on the first end face and the C-shaped metal fitting on the second end face, respectively. The precast concrete foundation according to claim 3.

5. The plurality of shear cotters are characterized in that one shear cotter is arranged vertically with an interval between them horizontally. The precast concrete foundation according to claim 1.

6. Both the first end face and the second end face are provided with a C-shaped fitting for engaging one end or the other end of the H-shaped fitting, a plurality of shear cotters arranged on both sides of the C-shaped fitting, and a shear cotter arranged below the C-shaped fitting. The H-shaped metal fitting is characterized in that one end and the other end of the H-shaped metal fitting are engaged with the C-shaped metal fitting on the first end face and the C-shaped metal fitting on the second end face, respectively. The precast concrete foundation according to claim 5.

7. The shear cotter is characterized by being a recess or a convex portion. A precast concrete foundation according to any one of claims 1 to 6.

8. The shear cotter is characterized by having a rectangular parallelepiped shape. The precast concrete foundation according to claim 7.

9. The shear cotter is characterized by having a truncated pyramidal shape. The precast concrete foundation according to claim 7.

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