JP7626585B2 - How to design the foundation structure of a detached building - Google Patents

Description

The present invention relates to a method for designing the foundation structure of a detached building having a columnar foundation structure.

Conventionally, as a building foundation supporting the base of a detached building, including a wooden structure, a building foundation having, for example, a rising wall portion, a slab footing, and a slab footing formed between the rising wall portion and the slab footing has been widely used.
In such detached buildings, moisture tends to accumulate under the floor, so there is a great demand for technology to improve the efficiency of the air cycle under the floor.
Meanwhile, various techniques have been disclosed for improving the air cycle efficiency of detached buildings (see, for example, Patent Document 1).

However, even if the technology described in Patent Document 1 improves the air cycle between the underfloor space and the attic in a detached building, the underfloor space, where moisture and other substances tend to accumulate, only has openings formed in the slab, so the improvement in air cycle efficiency is limited, and it is difficult to significantly improve the air cycle efficiency under the floor space.

As a result, a column foundation (columnar foundation structure), which is a cylindrical independent foundation, has been disclosed as a technology that can be applied to improve the efficiency of the air cycle by reducing the size of the walls of a slab or other structure erected under the floor (see, for example, Patent Document 2). The column foundation is placed over a linear underground beam and includes, for example, a vertically rising column main bar and a cylindrical concrete section that covers the main bar.

Traditionally, when designing foundation structures, including column foundations for detached buildings, the foundation structure has been designed individually for each detached building being constructed, depending on the bearing capacity of the soil, the weight of the building, the layout of the building, etc.

Japanese Utility Model Publication No. 63-040570 Japanese Patent Application Publication No. 11-043951

However, with the conventional foundation structure design method, in which the placement of column foundations was individually designed for each detached building being constructed, the design of the foundation structure took time and money, resulting in increased construction costs.

The present invention was made in consideration of these circumstances, and aims to provide a method for designing the foundation structure of a detached building that allows the design of the foundation structure of a detached building with a column foundation at low cost and in a short time.

In order to solve the above problems, the present invention proposes the following means.
That is, the design method of the foundation structure of the detached building of the present invention is a design method of the foundation structure of the detached building using a cylindrical foundation structure erected on a slab foundation, which is applicable to a detached building of two stories or less, a maximum height of 13 m or less, a maximum eaves height of 9 m or less, a floor height of 2.4 m to 3.0 m, and a bearing capacity of ²⁰ kN/m2 or more, and includes providing an outer periphery underground beam at the lower part of the outer wall of the detached building, forming a slab foundation main reinforcement structural part having a plurality of main reinforcements crossing each other along the horizontal direction on the inside of the outer periphery underground beam, and forming the slab foundation main reinforcement structural part into a plurality of sections in an endless manner along the lower part of the internal load-bearing wall of the detached building and between the adjacent slab foundation main reinforcement structural parts. The slab foundation is formed so that the maximum size of one section is 4,550 mm or less in both length and width, the cylindrical foundation structures are formed at intervals of 1,820 mm or less at least along the lower parts of the columns of the detached building and the internal underground beams, and when the interval between adjacent cylindrical foundation structures is 910 mm or more, a floor beam is formed in the middle part, and the cylindrical foundation structure further formed on the slab foundation is positioned directly below the base and so as to bear a floor load within a range of 16.0 m2 or less of ^the floor area of the first floor of the detached building.

The present invention provides a method for designing the foundation structure of a detached building that allows the design of the foundation structure of a detached building with a column foundation at low cost and in a short time.

This is an oblique view illustrating the state in which the foundation is installed on the building foundation. This is an oblique view explaining the general configuration of installing a foundation on a building foundation. FIG. 2 is a plan view for explaining an outline of a building foundation. FIG. 4 is a diagram for explaining the schematic configuration of the building foundation, and is a cross-sectional view taken along the line IV-IV in FIG. 3. FIG. 2 is a schematic plan view showing the arrangement of each part based on the design method for the foundation structure of a detached building of the present invention. This is an explanatory diagram showing an example of division of a slab foundation (slab floor) by internal underground beams. FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

Below, with reference to the drawings, a method for designing the foundation structure of a detached building according to one embodiment of the present invention will be described. Note that each embodiment shown below is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Also, the drawings used in the following description may show key parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

First, a schematic configuration of a building foundation including a columnar foundation structure formed by the molded member for columnar foundation structures of the present invention will be described.
FIG. 1 is a perspective view illustrating a state in which a base is installed on a building foundation, and FIG. 2 is a perspective view illustrating a schematic configuration of the building foundation.
The building foundation 1 comprises a rising wall portion 10 erected around a detached building (not shown), such as a two-story house, a slab foundation portion 20, an underground beam 30, a column base (columnar foundation structure) 40, and a floor beam 60.
In addition, the concrete portions constituting the rising wall portion 10, the slab foundation portion 20, the underground beams 30, and the column base 40 are integrally formed.

The foundation 2 of a detached building (not shown) is placed on the rising wall portion 10, and the pillars (not shown) of the detached building are erected. In addition, the foundation 2 and the pillars (not shown) are erected as appropriate between the column bases 40 formed on the underground beams 30.
In addition, floor beams 60 are provided below the base 2 and below the joists 6 as necessary.

Figure 3 is a plan view showing the general configuration of the building foundation, and Figure 4 is a cross-sectional view explaining the general configuration shown in the arrow IV-IV direction in Figure 3. For convenience, Figures 3 and 4 show simplified versions of parts of Figures 1 and 2.

The rising wall section 10 is erected, for example, around the exterior wall (periphery) of a detached building, and is formed around the slab foundation section 20. The rising wall section 10 includes a rising wall section main reinforcement 11 and a rising wall section concrete section 15.

The rising wall main reinforcement 11 has a rising portion 11A and an anchoring portion 11B, and the anchoring portion 11B is embedded in the slab foundation portion 20.
The rising wall concrete portion 15 is formed so as to cover the rising portion 11A.

The slab foundation section (slab floor) 20 is formed, for example, in the inner area surrounded by the rising wall section 10, and includes a slab foundation main reinforcement structural section 22 and a slab foundation concrete section 25.

The slab foundation main reinforcement structure 22 comprises a plurality of main reinforcements 22X arranged horizontally along the long side (first direction: X direction) of the rising wall portion 10, and a plurality of main reinforcements 22Y formed along the short side (second direction: Y direction) perpendicular to the direction in which the main reinforcements 22X are arranged.
The slab foundation concrete portion 25 has a thickness of, for example, about 200 mm, and is formed so as to cover the slab foundation main reinforcement structural portion 22 .

The underground beams 30 are composed of an outer periphery underground beam 30A arranged at the lower part of the rising wall part 10, and an inner underground beam 30B formed in the inner area surrounded by the outer periphery underground beam 30A so as to overlap with the mat foundation part 20. Such an underground beam 30 has a higher rigidity than the mat foundation part 20.
In addition, the internal underground beam 30B is formed along the long side (first direction: X direction) or the short side (second direction: Y direction) of the rising wall portion 10.

In this embodiment, the internal underground beam 30B comprises an underground beam main reinforcement structure 31, a diamond reinforcement section (reinforcement structure) 34, and an underground beam concrete section 35.
The underground beam main reinforcement structure 31 includes, for example, a plurality of underground beam main reinforcements 32 and a plurality of stirrups (hoop reinforcements) 33 .

The multiple underground beam main reinforcements 32 are formed, for example, along the long or short sides of the rising wall section 10, and are configured such that two (multiple) underground beam main reinforcements 32 are arranged horizontally, extending in parallel, in two sets (multiple) in the vertical direction.

In addition, the underground beam main reinforcements 32 arranged above and below are configured to be connected in the vertical direction by being surrounded by stirrups (hoops) 33, for example.
In addition, the underground beam main reinforcements 32 arranged above and below may be connected on three sides, the left and right and the bottom, to connect the underground beam main reinforcements 32 in the vertical direction.

In addition, in this embodiment, the diaphragm reinforcement portion 34 is formed below the position where the column base 40 is installed on the underground beam 30.
The diamond reinforcement section 34, for example, includes two (multiple) first reinforcement bars 34A that extend parallel to the underground beam main reinforcement bar 32 at a crossing angle of 45°, sandwiching the underground beam main reinforcement bar structural section 31, and two (multiple) second reinforcement bars 34B that extend parallel to the underground beam main reinforcement bar structural section 31 in a direction symmetrical to the first reinforcement bar 34A and the underground beam main reinforcement bar structural section 31, i.e., in a direction perpendicular to the first reinforcement bar 34A, sandwiching the underground beam main reinforcement bar structural section 31.

The underground beam concrete section 35 is formed to cover the underground beam main reinforcement structural section 31, and is, for example, approximately 300 mm thick in the vertical direction, which is thicker than the slab foundation concrete section 25.

(Columnar foundation structure molding member)
Next, the layout design of the column base (columnar foundation structure) based on the design method of the foundation structure of a detached building of the present invention will be described.
The following are examples of detached buildings to which the design method for the foundation structure of a detached building of the present invention can be applied.
(1) Structure: Wooden construction (conventional frame construction method)
(2) Building use: Detached house (3) Number of floors: 2 floors (4) Maximum height: 13m or less (5) Maximum eaves height: 9m or less (6) Floor height: 2.4m to 3.0m
(7) Earth bearing capacity: 20kN/m2 or ^more

First, when designing, the bearing capacity of the land on which the two-story wooden detached building is to be constructed must be confirmed. This must be determined, for example, by a ground survey, such as a Swedish sounding test, to ensure that the bearing capacity is 20 kN/ ^m2 or more. If the bearing capacity is less than 20 kN/ ^m2 , additional work such as ground improvement and reinforcement must be carried out.

Next, the positions of the columns and bearing walls of the detached building to be constructed are confirmed from the design drawings. For bearing walls, wall volume calculations and balance checks are to be carried out in accordance with Article 46 of the Enforcement Order of the Building Standards Act. The positions of the columns and bearing walls confirmed here will be referenced when designing the layout of the column base (columnar foundation structure), which will be described later.

FIG. 5 is a schematic plan view showing the layout of each part based on the design method of the foundation structure of a detached building of the present invention.
[Layout of outer foundation, internal underground beams, and slabs]
(1) The outer perimeter underground beams 30A are placed on the outer perimeter of the building.
(2-1) The internal underground beam 30B must be placed below the internal load-bearing wall W1.
(2-2) The internal underground beams 30B are placed on the lines that divide the slab foundation portion (slab floor) 20.
(2-3) Both ends of the internal underground beam 30B are positioned so as to contact the outer periphery underground beam 30A or other internal underground beams 30B, making the internal underground beam 30B endless.
(3) The size of the slab foundation portion (slab floor) 20 of one section surrounded by the outer underground beams 30A and the inner underground beams 30B shall be such that the maximum size is 4,550 mm or less in both length and width.
In addition, if the size of the slab foundation portion (slab floor) 20 of one section exceeds 4,550 mm in both length and width, an internal underground beam 30B is provided to divide the slab foundation portion (slab floor) 20 into two or more sections.
FIG. 6 shows an example of division of such a mat foundation portion (slab floor) 20 by internal underground beams 30B.

[Column-based placement]
(1) A column base (columnar foundation structure) 40 is placed directly below the column P1.
(2) The column base 40 is basically placed on the internal underground beam 30B. However, the column base 40 that satisfies the following conditions (2-1) and (2-2) may be placed on the mat foundation portion (slab floor) 20.
(2-1) A column base 40 located off the line of the internal underground beam 30B.
(2-2) Directly below where there are columns only on the first floor, or directly below where there are no columns and only the first floor load is borne (foundation/joists). In this case, the first floor floor area borne by the column base 40 is within 16.0 ^m2 . As an example, if the floor size of the location is 3.64 m x 3.185 m, the floor area is 11.6 ^m2 , which fits within 16.0 ^m2 , so the column base 40 can be installed.
(3) The column bases 40 are formed at intervals of 1820 mm or less along at least the lower part of the columns P1 of the detached building and along the internal underground beams 30B. When the interval between adjacent column bases 40 is 910 mm or more, a floor beam 60 (see FIG. 1) is formed in the middle part.

Based on the above-described design method for the foundation structure of a detached building of the present invention, by placing the outer perimeter foundation, internal underground beams, and slab floor, and then placing the column base, it is no longer necessary to design the column base placement each time according to the structure of each individual detached building, as was done in the past.
Therefore, it is possible to provide a method for designing the foundation structure of a detached building, which enables the design of the foundation structure of a detached building having a column foundation at low cost and in a short period of time.

FIG. 7 shows an example of a column base arrangement designed based on the design method for the foundation structure of a detached building of the present invention.
According to this embodiment, the position of the column base can be easily set in accordance with the above-mentioned design rules by simply identifying the outer underground beams 30A, the interior underground beams 30B, the slab foundation portion (slab floor) 20, etc. based on the floor plan of the detached building.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and gist of the invention.

REFERENCE SIGNS LIST 1 Building foundation 2 Foundation 3 Pillar 6 Joist 7 Joist 10 Rising wall section 11 Rising wall section main reinforcement 11A Rising section 11B Anchorage section 15 Rising wall section concrete section 20 Slab foundation section (slab floor)
22 Slab foundation main reinforcement structural part 25 Mat foundation concrete part 30 Underground beam 30A Peripheral underground beam 30B Internal underground beam 31 Underground beam main reinforcement structural part 32 Underground beam main reinforcement 33 Stirrup (hoop)
34 Diamond reinforcement section (reinforcement structure section)
35 Underground beam concrete section 40 Column base (columnar foundation structure)

Claims (1)

A design method for a foundation structure of a detached building using a cylindrical foundation structure erected on a slab foundation, which is applied to a detached building having a wooden structure of two stories or ^less , a maximum height of 13 m or less, a maximum eaves height of 9 m or less, a floor height of 2.4 m to 3.0 m, and a bearing capacity of 20 kN/m2 or more,
A periphery underground beam is provided at the lower part of the exterior wall of the detached building,
A mat foundation portion is formed on the inside of the outer periphery underground beam, the mat foundation portion being provided with a slab foundation main reinforcement structure portion having a plurality of main reinforcements crossing each other along a horizontal direction,
An internal underground beam is formed endlessly along the lower part of the internal load-bearing wall of the detached building and between the adjacent slab foundation main reinforcement structural parts, forming the slab foundation part into a plurality of sections;
The maximum size of each section of the mat foundation is 4,550 mm or less in both length and width,
The cylindrical foundation structure is formed at least along the lower part of the column of the detached building and the internal underground beam at intervals of 1820 mm or less,
When the interval between the adjacent cylindrical foundation structures is 910 mm or more, a floor beam is formed in the middle portion,
A method for designing the foundation structure of a detached building , characterized in that the cylindrical foundation structure further formed on the slab foundation portion is positioned directly below the base and so as to bear a floor load of up to 16.0 ^m2 of the floor area of the first floor of the detached building.

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