JP7253333B2 - Exposed column base structure and building - Google Patents

Description

The present invention relates to exposed column base structures and buildings.

Conventionally, an exposed column base structure has been put into practical use, in which the columns of buildings such as steel frames and steel pipe concrete structures are fixed to the foundation concrete via base plates. It is often used for small-scale steel-frame buildings such as houses.

In small-scale steel-framed buildings, it is required to make the outer diameter of the foundation column type as small as possible in order to secure a large building area in a narrow space. For this reason, at present, a tapered column that is configured so that the diameter becomes smaller as it goes down, or a small-diameter cylindrical column is used via a flat diaphragm, and the steel frame near the base of the column is used. A technique has been proposed for reducing the outer diameter of foundation column-shaped concrete by reducing the diameter of the columns (see, for example, Patent Document 1).

JP-A-10-183759

However, the tapered column is difficult to manufacture, and has poor deformability at the small diameter portion, so that the structural performance tends to be unstable. In addition, a flat diaphragm for connecting a small-diameter cylindrical column to the lower end of a large-diameter steel column body requires a complicated design. Since it was necessary to adopt a large and thick diaphragm to prevent collapse, there was a problem that a large amount of labor and cost was required in the manufacture and design of the exposed column base structure.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide an exposed column base structure that can keep the outer diameter of the foundation column small while ensuring good structural performance. .

In order to achieve the above object, an exposed column base structure according to the present invention uses a plurality of anchor bolts to fix a base plate fixed to the lower end of a steel-pipe steel frame column of a building to foundation concrete. A steel pipe steel frame column has a large diameter portion with a predetermined outer diameter, a smaller outer diameter than the large diameter portion, a predetermined length, and a vertical length than the large diameter portion. It has a small diameter portion arranged downward in the direction, a diaphragm connecting the large diameter portion and the small diameter portion, and the diaphragm has a tapered inner peripheral surface.

By adopting such a configuration, it is possible to reduce the diameter of the base plate by reducing the diameter of the lower portion of the steel pipe steel frame column, thereby making it possible to reduce the outer diameter of the foundation concrete. Therefore, since the space required for installing the exposed column base structure can be saved, the site can be effectively utilized. In addition, the large-diameter part and the small-diameter part of the steel pipe steel column are connected via a diaphragm that secures the length of the small-diameter part with a uniform cross section and has a tapered inner peripheral surface that suppresses deformation and excels in stress transmission. Therefore, the plastic deformation capability (energy absorption capability) at the small diameter portion can be improved.

In the exposed column base structure according to the present invention, the diaphragm can be a tubular diaphragm. The tubular diaphragm has a large diameter opening having an inner diameter corresponding to the inner diameter of the large diameter portion and a small diameter opening having an inner diameter corresponding to the inner diameter of the small diameter portion, the tapered inner peripheral surface being the large diameter opening. and the small diameter opening can be connected.

By adopting such a configuration, the weight of the diaphragm can be reduced, and the connection between the large-diameter opening and the small-diameter opening can be facilitated.

In the exposed-type column base structure according to the present invention, the length of the small diameter portion can be set to 0.8 times or more (and, for example, 1.2 times or less) of the outer diameter of the small diameter portion.

By adopting such a configuration, the length of the small diameter part of the steel pipe steel frame column is set to a specific value (0.8 times or more of the outer diameter of the small diameter part), so the plastic deformation capacity at the bottom of the column is greatly improved. can be made

In the exposed type column base structure according to the present invention, the outer diameter of the large diameter portion and the outer diameter of the diaphragm can be set to be substantially the same.

By adopting such a configuration, it is possible to prevent the occurrence of a step at the joint between the large-diameter portion and the diaphragm, thereby preventing interference with the inner surface of the outer wall and interior finishing.

In the exposed type column base structure according to the present invention, the cross-sectional area of the large-diameter portion and the cross-sectional area of the small-diameter portion can be set to be substantially the same.

By adopting such a configuration, the large-diameter portion and the small-diameter portion can have the same proof stress against the axial force (force caused by the weight of the building, etc.) generated in the steel pipe steel frame column.

A first building according to the present invention is a steel pipe erected with an exposed column base structure in which a base plate fixed to the lower end of a steel pipe steel frame column of the building is fixed to foundation concrete using a plurality of anchor bolts. The steel pipe steel frame column has a plurality of steel columns, and the steel pipe steel column has a large diameter portion having a predetermined outer diameter, and an outer diameter smaller than the large diameter portion and a predetermined length. It has a small diameter portion arranged downward in the direction and a diaphragm connecting the large diameter portion and the small diameter portion, and the length of the small diameter portion in all the steel pipe steel frame columns is set to the same value is.

By adopting such a configuration, the length of the small diameter portion of all steel pipe steel columns (that is, the distance from the top surface of the base plate to the bottom end of the diaphragm) is set to the same value, so the cross-section change position setting during structural calculation becomes easier. In addition, since the member lengths of the small-diameter portions are uniform, labor required for procurement and processing of members can be reduced.

A second building according to the present invention is a steel pipe erected with an exposed column base structure in which a base plate fixed to the lower end of a steel pipe steel frame column of the building is fixed to foundation concrete using a plurality of anchor bolts. The steel pipe steel frame column has a plurality of steel columns, and the steel pipe steel column has a large diameter portion having a predetermined outer diameter, and an outer diameter smaller than the large diameter portion and a predetermined length. It has a small diameter part arranged downward in the direction and a diaphragm connecting the large diameter part and the small diameter part, and the length of the small diameter part in the steel pipe steel frame column is 0.2 to 0.5 times the floor height It is set in the range.

In a typical building composed of columns and beams, the point of inflection (the point where the bending direction of the column changes) is 0.2 to 0.5 times the floor height (almost equal to the total length of the column). It is known that the force that bends the column is small in the vicinity of this inflection point. Therefore, by setting the length of the small diameter portion in the range of 0.2 to 0.5 times the floor height so that the diaphragm is arranged in the range where such a reflex point exists, the vertical length of the diaphragm is reduced. can be shortened.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the exposure type|mold column base structure which can hold down the outer diameter size of a base column type|mold small, ensuring favorable structural performance.

It is a side view for explaining composition of exposed type column base structure concerning an embodiment of the present invention. 1. It is an enlarged side view of the tubular diaphragm vicinity part of the steel-pipe steel frame column which comprises the exposure type|mold column base structure shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the following embodiments are examples for explaining the present invention, and the present invention is not limited only to these embodiments. Therefore, the present invention can be embodied in various forms without departing from the gist thereof.

First, the configuration of an exposed column base structure 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

The exposed type column base structure 1 according to the present embodiment uses a plurality of anchor bolts B fixed to the foundation concrete C to fix the base plate P fixed to the lower end of the steel pipe steel frame column 10 of the building to the foundation concrete C. By doing so, the steel pipe steel frame column 10 is erected.

The anchor bolts B are made of SD490 steel, for example, and are arranged one by one only at each corner of the base plate P (four bolts in total). Each anchor bolt B has a first portion B ₁ embedded in the foundation concrete C and a second portion B ₂ not embedded in the foundation concrete C. If the second portion _B2 of the anchor bolt B has a diameter smaller than that of the first portion _B1 , stress can be concentrated on the second portion _B2 , and the second portion _B2 is subjected to tensile deformation and shearing. Deformation can be generated intensively. In addition, the number of anchor bolts B is not limited to four, and the number can be appropriately set according to the size of the foundation concrete C or the like.

The base plate P is a plate-shaped member having a predetermined thickness made of steel plate, casting, forging, or the like, and is integrally provided at the lower end of the steel pipe steel frame column 10 of the building. The base plate P in this embodiment has a rectangular shape in plan view, and is provided with insertion holes (not shown) through which the anchor bolts B are inserted at each corner thereof. A space formed between the insertion hole of the base plate P and the anchor bolt B inserted through the insertion hole is filled with grout.

Although not shown, in a region outside the region surrounded by the four anchor bolts 10 in the foundation concrete C, a plurality of vertical reinforcing bars extending in the vertical direction are arranged at predetermined intervals. Further, horizontal reinforcing bars extending horizontally are arranged around the vertical reinforcing bars so as to surround the outer sides of the vertical reinforcing bars. The vertical reinforcing bars function to suppress the occurrence of cone-shaped failure of the foundation concrete C, while the horizontal reinforcing bars function to constrain the vertical reinforcing bars and increase anchoring strength. The numbers of vertical reinforcing bars and horizontal reinforcing bars can be appropriately set so as to satisfy a predetermined condition.

As shown in FIG. 1, the steel pipe steel frame column 10 has a large diameter portion 11 having a predetermined outer diameter _D1 , an outer diameter _D2 smaller than the large diameter portion 11, and a predetermined length _L2 . It has a small diameter portion 12 arranged below the large diameter portion 11 in the vertical direction, and a tubular diaphragm 13 connecting the large diameter portion 11 and the small diameter portion 12 .

As the large-diameter portion 11 and the small-diameter portion 12, for example, hollow steel pipes satisfying a predetermined standard strength can be employed. In the present embodiment, cylindrical steel pipes are used as the large-diameter portion 11 and the small-diameter portion 12, but rectangular steel pipes may be used. The cross-sectional area of the large diameter portion 11 can be set to be substantially the same as the cross-sectional area of the small diameter portion 11 . In this way, the large-diameter portion 11 and the small-diameter portion 12 can have the same yield strength against the axial force (the force caused by the weight of the building, etc.) generated in the steel pipe steel frame column 10 .

The outer diameter D ₁ of the large-diameter portion 11 can be appropriately set (for example, within the range of 250 to 750 mm) depending on the scale and specifications of the building. The plate thickness of the large-diameter portion 11 can be appropriately set according to the size of the outer diameter D ₁ of the large-diameter portion 11 . For example, when the outer diameter D ₁ is set to 250 mm, the plate thickness can be set to 6 to 16 mm, and when the outer diameter D ₁ is set to 750 mm, the plate thickness can be set to 19 to 32 mm.

The outer diameter D ₂ of the small diameter portion 12 can be set to approximately 0.6 to 0.9 times the outer diameter D ₁ of the large diameter portion 11 . For example, when the outer diameter D ₁ of the large diameter portion 11 is 250 mm, the outer diameter D ₂ of the small diameter portion 12 can be set to 150 mm. Further, when the outer diameter D ₁ of the large diameter portion 11 is 500 mm, the outer diameter D ₂ of the small diameter portion 12 can be set to 400 mm. The plate thickness of the small diameter portion 11 can be appropriately set according to the size of the outer diameter D ₂ of the small diameter portion 12 . For example, when the outer diameter D ₂ is set to 150 mm, the plate thickness can be set to 6 to 12 mm, and when the outer diameter D ₂ is set to 400 mm, the plate thickness can be set to 9 to 25 mm.

In order to make the cross-sectional area of the large-diameter portion 11 and the cross-sectional area of the small-diameter portion 12 approximately the same, for example, when the outer diameter _D1 of the large-diameter portion 11 is set to 500 mm and the outer diameter _D2 of the small-diameter portion 12 is set to 400 mm, The plate thickness of the large diameter portion 11 may be set to 19 mm, and the plate thickness of the small diameter portion 12 may be set to 25 mm. Further, when the strength of the large diameter portion 11 and the small diameter portion 12 are different, by changing the plate thickness according to each strength, the large diameter portion 11 and the small diameter portion 12 have the same proof stress against the axial force. can be made

The length L ₂ of the small diameter portion 12 is set to 0.8 times or more the outer diameter D ₂ of the small diameter portion 12 . If the length L ₂ of the small diameter portion 12 is less than 0.8 times the outer diameter D ₂ , deformation is concentrated on the small diameter portion 12 , resulting in poor plastic deformation capability, which is not preferable. For example, when the outer diameter D ₂ of the small diameter portion 12 is 400 mm, the length L ₂ of the small diameter portion 12 is set to 320 mm or more. On the other hand, if the length _L2 of the small-diameter portion 12 is long, the deformability is ensured although the buckling may cause instability. Further, even if the tubular diaphragm 13 becomes unstable due to buckling, the length _L2 of the small-diameter portion 12 is set to, for example, 1.2 times or less of the outer diameter _D2 of the small-diameter portion 12, so that the tubular diaphragm 13 buckling, resulting in increased deformability of the small diameter portion 12 .

The tubular diaphragm 13 is a tubular steel pipe member that connects the large-diameter portion 11 and the small-diameter portion 12, and as shown in FIG. are doing. In the present embodiment, the cylindrical tubular diaphragm 13 is used to correspond to the shapes of the large diameter portion 11 and the small diameter portion 12, but a square cylindrical tubular diaphragm 13 may be used. The diaphragm in the present invention is not limited to a tubular one having a through hole, and may be a diaphragm having a partially closed portion. However, a tubular diaphragm is preferable because it can reduce weight.

The tubular diaphragm 13 includes a large-diameter opening 13a having an inner diameter _D31 corresponding to the inner diameter _D11 of the large-diameter portion 11, a small-diameter opening 13b having an inner diameter _D32 corresponding to the inner diameter _D22 of the small-diameter portion 12, and a large-diameter opening 13b. and a tapered inner peripheral surface 13c connecting the diameter opening 13a and the small diameter opening 13b. Here, “corresponding” means that the inner diameter D ₃₁ (D ₃₂ ) of the large-diameter opening 13a (small-diameter opening 13b) is the same as the inner diameter D 11 (D 22 ) of the large-diameter portion ₁₁ (small-diameter portion ₁₂ ). This does not mean that the dimension is set _to be "same" as the dimension, but as shown in _FIG . This is a concept that includes setting the inner diameter D ₁₁ (D ₂₂ ) of 12) to be slightly smaller.

For example, when the inner diameter D ₁₁ of the large diameter portion 11 is 436 mm, the inner diameter D ₃₁ of the large diameter opening 13a of the tubular diaphragm 13 can be set to about 410 to 420 mm, and the inner diameter D ₂₂ of the small diameter portion 12 can be set to about 410 to 420 mm. In the case of 350 mm, the inner diameter D ₃₂ of the small-diameter opening 13b of the tubular diaphragm 14 can be set to about 330-340 mm. Further, when the inner diameter D ₁₁ of the large diameter portion 11 is 218 mm, the inner diameter D ₃₁ of the large diameter opening 13a of the tubular diaphragm 13 can be set to about 200 to 210 mm, and the inner diameter D ₂₂ of the small diameter portion 12 can be set to about 200 to 210 mm. In the case of 126 mm, the inner diameter D ₃₂ of the small-diameter opening 13b of the tubular diaphragm 14 can be set to about 110 to 120 mm.

In this embodiment, as shown in FIG. 2, the outer diameter _D3 of the tubular diaphragm 13 is set substantially equal to the outer diameter _D1 of the large diameter portion 11. As shown in FIG. The outer diameter of a general flat plate-shaped diaphragm is set about 50 to 60 mm larger than the outer diameter of the steel column body, but in this case, interference with the inner surface of the outer wall or interior finishing may occur. By setting the outer diameter _D3 of the tubular diaphragm 13 to be substantially the same as the outer diameter _D1 of the large-diameter portion 11 as in the present embodiment, the occurrence of a step at the joint between the large-diameter portion 11 and the tubular diaphragm 13 can be prevented. Since it can be prevented, it is possible to prevent interference with the inner surface of the outer wall and the interior finish.

In _addition , when the tubular diaphragm 13 is viewed from the side as shown in FIG. Assuming that the angle formed by V ₂ is θ, it is preferable to set θ to 45° or less. By doing so, the efficiency of transmission from the large-diameter portion 11 to the small-diameter portion 12 can be increased, and deformation of the tubular diaphragm 13 can be suppressed.

Next, a variation of a building provided with a plurality of steel pipe steel columns 10 erected by the exposed column base structure 1 according to this embodiment will be described.

<First building>
In the first building, the length L ₂ of the small diameter portion 12 in all the steel pipe steel columns 10 is set to the same value. In a building having such a configuration, the length L ₂ of the small diameter portion 12 (that is, the distance from the upper surface of the base plate P to the lower end of the diaphragm 13) in all the steel pipe steel columns 10 is set to the same value, It becomes easy to set cross-section change position at the time of structural calculation. Further, since the member lengths of the small-diameter portions 12 are uniform, labor required for procurement and processing of members can be reduced. In general buildings, it is extremely rare for the cross section to change in the middle of a column, and structural calculation software that has a function to change the cross section in the middle of a column is rare. can be calculated by setting In this case _, if the length _L2 of the small diameter portion 12 is uneven, setting the virtual floors becomes complicated. Such an effect is preferably exhibited when the diaphragm having the tapered inner peripheral surface of the present invention is arranged, but a certain effect is exhibited even when a diaphragm having no tapered inner peripheral surface is used. can do.

<Second building>
In the second building, the length L ₂ of the small-diameter portion 12 of the steel pipe steel column 10 is set within the range of 0.2 to 0.5 times the floor height. In a typical building composed of columns and beams, the point of inflection (the point where the bending direction of the column changes) is 0.2 to 0.5 times the floor height (almost equal to the total length of the column). It is known that the force that bends the column is small in the vicinity of this inflection point. Therefore, by setting the length L ₂ of the small diameter portion 12 in the range of 0.2 to 0.5 times the floor height so that the tubular diaphragm 13 is arranged in the range where such reflex points exist, the tubular diaphragm The vertical length of 13 can be shortened. For example, in a building with a floor height (approximately equal to the total length of the steel pipe steel frame column 10) of 2.5 m, the length L ₂ of the small diameter portion 12 is set within the range of 500 to 1250 mm. Such an effect is preferably exhibited when the diaphragm having the tapered inner peripheral surface of the present invention is arranged, but a certain effect is exhibited even when a diaphragm having no tapered inner peripheral surface is used. can do.

In the exposed column base structure 1 according to the embodiment described above, since the diameter of the lower portion of the steel pipe steel frame column 10 can be reduced, the diameter of the base plate P can be reduced. It is possible to keep the dimensions small. Therefore, since the space required for installing the exposed column base structure 1 can be saved, the site can be effectively utilized. In addition, since the large diameter portion 11 and the small diameter portion 12 of the steel pipe steel frame column 10 are connected via the tubular diaphragm 13 having a tapered inner peripheral surface 13c that suppresses deformation and is excellent in stress transmission, Plastic deformation ability (energy absorption ability) can be improved. In particular, in the exposed column base structure 1 according to the present embodiment, the length L ₂ of the small diameter portion 12 of the steel pipe steel frame column 10 is set to a specific value (0.8 times or more the outer diameter D ₂ of the small diameter portion 12). Since it is set, the plastic deformation ability at the bottom of the column can be significantly improved.

Further, in the exposed column base structure 1 according to the embodiment described above, the outer diameter _D1 of the large-diameter portion 11 and the outer diameter _D3 of the tubular diaphragm 13 are set to be substantially the same. Since it is possible to prevent the occurrence of a step at the joint between the diameter portion 11 and the tubular diaphragm 13, it is possible to prevent interference with the inner surface of the outer wall and interior finishing.

Further, in the exposed type column base structure 1 according to the embodiment described above, the cross-sectional area of the large-diameter portion 11 and the cross-sectional area of the small-diameter portion 12 are set to be substantially the same, so that the axial force generated in the steel pipe steel frame column 10 The large-diameter portion 11 and the small-diameter portion 12 can have the same yield strength against (force caused by the weight of the building, etc.).

The present invention is not limited to the above embodiments, and any design modifications made by those skilled in the art to such embodiments are also included in the scope of the present invention as long as they have the features of the present invention. . That is, each element provided in the embodiment and its arrangement, material, condition, shape, size, etc. are not limited to those illustrated and can be changed as appropriate. In addition, each element provided in the above embodiment can be combined as long as it is technically possible, and a combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

REFERENCE SIGNS LIST 1 Exposed column base structure 10 Steel pipe steel column 11 Large diameter portion 12 Small diameter portion 13 Tubular diaphragm 13a Large diameter opening 13b Small diameter opening 13c Tapered inner circumferential surface B Anchor bolt C Foundation Concrete _D1 ... Outer diameter of large diameter part _D11 ... Inner diameter of large diameter part _D2 ... Outer diameter of small diameter part _D22 ... Inner diameter of small diameter part _D3 ... Outer diameter of tubular diaphragm _D31 ... Large diameter opening of tubular diaphragm inner diameter of the part D ₃₂ ... inner diameter of the small diameter opening of the tubular diaphragm L ₂ ... length of the small diameter part P ... base plate

Claims (6)

An exposed column base structure in which the steel pipe steel frame column is erected by fixing a base plate fixed to the lower end of the steel pipe steel frame column of the building to the foundation concrete using a plurality of anchor bolts,
The steel pipe steel frame column has a large diameter portion having a predetermined outer diameter, and a small diameter portion having an outer diameter smaller than that of the large diameter portion and having a predetermined length and disposed vertically below the large diameter portion. and a diaphragm connecting the large diameter portion and the small diameter portion,
The diaphragm is a tubular steel pipe member that connects the large diameter portion and the small diameter portion, and has a tapered inner peripheral surface,
The outer diameter of the diaphragm is uniform and substantially the same as the outer diameter of the large diameter portion ,
The diaphragm has a large-diameter opening having an inner diameter smaller than the inner diameter of the large-diameter portion and a small-diameter opening having an inner diameter smaller than the inner diameter of the small-diameter portion. An exposed column base structure that connects the opening and the small-diameter opening . 2. The exposed column base structure according to claim 1 , wherein the length of said small diameter portion is set to be 0.8 times or more the outer diameter of said small diameter portion. The exposed type column base structure according to claim 1 or 2 , wherein the length of said small diameter portion is set to be 0.8 times or more and 1.2 times or less of the outer diameter of said small diameter portion. The exposed type column base structure according to any one of claims 1 to 3 , wherein the cross-sectional area of the large-diameter portion and the cross-sectional area of the small-diameter portion are substantially the same. A building comprising a plurality of the steel pipe steel columns erected with an exposed column base structure in which a base plate fixed to the lower end of the steel pipe steel frame column of the building is fixed to the foundation concrete using a plurality of anchor bolts,
The steel pipe steel frame column has a large diameter portion having a predetermined outer diameter, and a small diameter portion having an outer diameter smaller than that of the large diameter portion and having a predetermined length and disposed vertically below the large diameter portion. and a diaphragm connecting the large diameter portion and the small diameter portion,
The length of the small diameter portion of all the steel pipe steel columns is set to the same value,
The diaphragm is a tubular steel pipe member that connects the large diameter portion and the small diameter portion, and has a tapered inner peripheral surface,
The outer diameter of the diaphragm is uniform and substantially the same as the outer diameter of the large diameter portion ,
The diaphragm has a large-diameter opening having an inner diameter smaller than the inner diameter of the large-diameter portion and a small-diameter opening having an inner diameter smaller than the inner diameter of the small-diameter portion. A building that connects the opening and the small-diameter opening . A building comprising a plurality of the steel pipe steel columns erected with an exposed column base structure in which a base plate fixed to the lower end of the steel pipe steel frame column of the building is fixed to the foundation concrete using a plurality of anchor bolts,
The steel pipe steel frame column has a large diameter portion having a predetermined outer diameter, and a small diameter portion having an outer diameter smaller than that of the large diameter portion and having a predetermined length and disposed vertically below the large diameter portion. and a diaphragm connecting the large diameter portion and the small diameter portion,
The building, wherein the length of the small diameter portion of the steel pipe steel frame column is set within a range of 0.2 to 0.5 times the floor height.

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