JP2024030269A - Column base structure - Google Patents

Abstract

To provide a column base structure of construction capable of reducing the bending moment with a simple structure.SOLUTION: The column base has a column body 3, and a base plate 5 joined to the bottom end of the column body 3. The column base is placed in a space formed by a surrounding slab concrete 13 and is buried with filler concrete 15. That is, the area around the column base is filled with the filler concrete 15. At least in part between the filler concrete 15 and the foundation 11, an elastic member 19a capable of compression deformation is arranged. Also, between the filler concrete 15 and the surrounding concrete slab 13, an elastic member 19b capable of compression deformation is arranged. That is, the entire circumference of the column base is surrounded by the elastic member 19b.SELECTED DRAWING: Figure 1

Description

The present invention relates to a column base structure for a structure.

As shown in FIG. 6, a typical structure 100 is composed of columns 101, beams 105, and the like. Column body 101 is joined to foundation 103. When a lateral force X is applied to such a structure 100, a bending moment M is generated in the column 101. In this case, the largest bending moment occurs at the joint between the column 101 and the foundation 103. Therefore, in order to suppress deformation of the column 101 and the foundation 103, high rigidity is required.

As a structure for connecting the lower part of the column 101 to the foundation 103, a common method is to fix a base plate joined to the column base to the foundation using anchor bolts (for example, Patent Document 1).

JP2013-64244A

Here, for example, in a low-to-medium-rise structure, the rigidity of the steel columns 101 and beams 105 is sufficient, but the rigidity of the concrete foundation 103 may be insufficient. In order to obtain a stronger foundation 103, a larger and deeper foundation 103 is required. For example, since the steel used for the column 101 is a standard product, even if the cheapest column 101 is selected, there may be sufficient margin for the rigidity required for a mid- to low-rise structure. On the other hand, the column base structure at the joint between the foundation 103 and the column body 101 needs to have sufficient rigidity to withstand the bending moment, which has been a factor in increasing costs.

On the other hand, there is also a method in which the joint between the foundation 103 and the column 101 has a pin structure. By using a pin structure, the bending moment generated in the column base can be reduced. Therefore, the foundation 103 can be smaller.

On the other hand, from the viewpoint of aesthetics, etc., a space may be formed in a part of a floor slab, a column pedestal structure is constructed in the space, and then a part of the column pedestal including the base plate is buried with filled concrete. However, with such a structure, even if the joint between the foundation 103 and the column 101 is a pin structure, the column base is restrained by the filling concrete around the column base and the concrete that makes up the surrounding floor slab. Therefore, there was a problem in that rotational deformation of the column base was hindered, and the above-mentioned effects could not be sufficiently obtained.

The present invention was made in view of such problems, and an object of the present invention is to provide a column base structure for a structure that has a simple structure and is capable of reducing bending moments.

In order to achieve the above-mentioned object, the present invention provides a column base having a column body and a base plate joined to the lower end of the column body, a foundation to which the base plate is fixed, and a base plate provided around the column base. and a compressively deformable elastic member is disposed between at least a portion of the filling concrete and the foundation, and between the filling concrete and surrounding slab concrete. It has a pillar base structure.

The base plate may include a hole through which an anchor bolt is inserted, and a slit formed at least partially around the hole, and a portion surrounded by the slit may function as an easily deformable portion. .

The elastic member placed between the filling concrete and the foundation may be placed over the entire circumference of the column base in plan view, or may be placed between the filling concrete and the foundation. The elastic member does not need to be arranged on at least one side of the column base in the circumferential direction in a plan view.

According to the present invention, by arranging compressively deformable elastic members around and below the filler concrete in which the column base is buried, the filler concrete is allowed to move between the surrounding slab concrete and the foundation. Ru. Therefore, when a bending moment is applied to the column base, the filled concrete itself rotates together with the column base, thereby reducing the bending moment.

Further, by making slits in the base plate, the base plate becomes easily deformable, and the column base becomes easy to rotate and deform. Therefore, the bending moment generated in the column base can be further reduced.

Moreover, if the elastic member placed between the filling concrete and the foundation is placed around the entire circumference of the column pedestal, the column pedestal can be allowed to rotate in all directions.

On the other hand, by not placing the elastic member placed between the filler concrete and the foundation in one direction of the column base, the elastic member can be placed in a direction where rotation of the column base does not occur, or in a direction where rotation is desired to be restricted. can be reduced.

According to the present invention, it is possible to provide a column base structure for a structure that has a simple structure and can reduce bending moment.

A diagram showing a column base structure 1. FIG. 2 is a sectional view taken along line AA in FIG. 1. A diagram showing a column base structure 1a. A diagram showing a column base structure 1b. (a), (b) is a figure showing operation of pillar structure 1. A conceptual diagram showing a structure 100.

Hereinafter, a column pedestal structure 1 according to an embodiment of the present invention will be described. FIG. 1 is a front view showing the column base structure 1, and FIG. 2 is a sectional view taken along the line AA in FIG. Note that FIGS. 1 and 2 are perspective views of the filled concrete 15. The column base structure 1 mainly includes a column 3, a base plate 5, an anchor bolt 9, a foundation 11, a filled concrete 15, elastic members 19a, 19b, and the like.

The column base includes a column 3 and a base plate 5 joined to the lower end of the column 3. In the illustrated example, the column body 3 is an H steel column, but it may be a round column or a square column. Further, in the illustrated example, the brace 17 is joined to one side of the column 3 via a gusset plate, but the brace 17 is not necessarily required, and additional braces 17 may be arranged in different directions. It's okay.

The base plate 5 is a plate-like member made of steel. A plurality of holes are provided in the base plate 5 around the joint portion with the columnar body 3, and an anchor bolt 9 is inserted into each hole. One end of the anchor bolt 9 is buried in the foundation 11, and the base plate 5 is fixed to the foundation 11 by the anchor bolt 9.

Note that the arrangement and number of anchor bolts 9 are not particularly limited, but for example, they may be arranged near the four corners of the base plate 5, or as shown in FIG. You can also use it as

Mortar 7 is filled between the base plate 5 and the foundation 11. That is, no gap is formed below the base plate 5 with the foundation 11, and the entire lower surface of the base plate 5 contacts the mortar 7.

The column base is placed in a space formed in the surrounding concrete slab 13 (floor slab) and is buried with filling concrete 15. That is, filling concrete 15 is provided around the column base and is integrated with the column base. At least a portion between the filling concrete 15 and the foundation 11 is provided with a compressively deformable elastic member 19a. Further, an elastic member 19b that can be compressed and deformed is arranged between the filling concrete 15 and the surrounding concrete slab 13.

The elastic members 19b are arranged in four directions so as to surround the entire periphery of the column base. On the other hand, in the illustrated example, the elastic member 19a is arranged only on the side where the brace 17 is installed with respect to the base plate 5, and the elastic member 19a is not arranged in other directions.

Note that, as shown in FIG. 2, in this embodiment, the elastic member 19a is not arranged on the opposite side to where the brace 17 is arranged and in the direction perpendicular to the installation direction of the brace 17. , but not limited to this. That is, the arrangement of the elastic member 19a is not particularly limited as long as it is arranged on at least one side between the column base and the elastic member 19b.

For example, the elastic member 19a may be placed on the opposite side to the side where the brace 17 is placed, and the elastic member 19a may be placed in two directions between the column base and the elastic member 19b. Alternatively, the elastic member 19a may be arranged in one or both directions perpendicular to the installation direction of the brace 17, and the elastic member 19a may be arranged in two or three directions between the column base and the elastic member 19b. good.

Further, for example, as in the column pedestal structure 1a shown in FIG. 3, the elastic member 19a arranged between the filling concrete 15 and the foundation 11 may be arranged over the entire circumference of the column pedestal (base plate 5). In this way, as long as the elastic member 19a is arranged in at least one direction with respect to the circumferential direction of the column pedestal (base plate 5) in plan view, it may be arranged all around the column pedestal (four directions of the column pedestal); The elastic member 19a may not be disposed on one side.

Moreover, you may use the base plate 5a like the column base structure 1b shown in FIG. The base plate 5a is provided with a slit 21 at least partially around the anchor bolt 9 (the hole through which the anchor bolt is inserted). The slit 21 is formed in a substantially L-shape from the side surface of the base plate 5a. That is, the slits 21 are formed to surround each anchor bolt 9 (hole in the base plate 5a) from at least two directions.

In this manner, the anchor bolt 9 is arranged between the slits 21 in two different directions, so that the easily deformable portion 23 can be formed in the base plate 5a fixed with the anchor bolt 9. The easily deformable portion 23 is a portion where the base plate 5a deforms when an external force is applied to the column 3, allowing rotational deformation of the column 3. Note that the slit 21 is not necessarily essential.

The elastic members 19a and 19b can be made of, for example, foam or rubber. Normally, when pouring slab concrete 13, a formwork is installed on the foundation 11 so as to surround the part where the column base is to be installed, and concrete is placed outside the formwork. A space can be formed in the concrete 13 (so-called box cutting) in which a column base is installed.

At this time, a formwork such as the slab concrete 13 may be used as is as the elastic member 19b. For example, before placing the slab concrete 13, an elastic member 19b is installed around the area where the column base is to be installed, and the slab concrete 13 is placed in this state. Furthermore, after installing the column base in the space, the elastic member 19a is installed on the foundation 11, and the filling concrete 15 is placed so as to fill the space. Through the above steps, the column base structure 1 can be constructed.

In addition, when using the elastic member 19b in the formwork of the slab concrete 13, the elastic member 19b is compressed without being completely crushed by the lateral pressure of the slab concrete 13 and the lateral pressure of the filling concrete 15 that will be placed afterwards. It is necessary to have a compressive elastic modulus and thickness to the extent that elastic deformability remains. Similarly, the elastic member 19a disposed on the foundation 11 should have a compressive elastic modulus and a thickness that will not completely collapse when the filling concrete 15 is cast above, and will still have compressive elastic deformability. Must have.

Next, the operation when a bending moment is applied to the column base structure 1 will be described. Note that the same applies to the column base structures 1a and 1b. FIG. 5(a) is a partial cross-sectional view of the column base structure 1. As described above, the base plate 5 is fixed on the foundation 11, and the base plate 5 and the columns 3 (and a part of the gusset plate, etc.) are buried in the filling concrete 15. Elastic members 19a and 19b are arranged around and below the filling concrete 15.

As shown in FIG. 5(b), in this state, for example, when a force is applied to the column 3 in the direction of the brace 17 (arrow B in the figure), a portion of the elastic members 19a and 19b collapses, causing the filled concrete to collapse. 15, the column base is allowed to rotate in the B direction. In this way, by rotating the column base with respect to the foundation 11 (slab concrete 13), the bending moment applied to the column base can be reduced.

Note that when the force in the B direction is removed, the column base returns to its original state. At this time, the elastic members 19a and 19b also return to their original states, and the formation of a gap between the filled concrete 15 and the slab concrete 13 is suppressed.

As described above, according to the present embodiment, when an external force is applied to the column body 3, rotational deformation of the filling concrete 15 integrated with the column base is allowed due to compressive elastic deformation of the elastic members 19a and 19b. Can be done. Therefore, the rotational rigidity of the column base can be reduced. Therefore, it is possible to reduce the bending moment applied to the column base with a simple structure.

At this time, the elastic member 19a is placed on the foundation 11, and the elastic member 19b only needs to be placed around the column base, so there is no need to make it into a special shape depending on the shape and external shape of the column base. For example, when attempting to arrange elastic members on the outer surface of a column base, it is necessary to arrange the elastic members finely to match the uneven shape of the outer surface of the column 3 and the brace 17, which makes construction difficult. In this embodiment, plate-shaped members can be used as they are as the elastic members 19a and 19b. Therefore, construction is easy.

Furthermore, forming the slit 21 in the base plate 5 also facilitates deformation of the base plate 5. Therefore, even by deforming the base plate 5, the effect of reducing the bending moment to the column base can be obtained.

Further, the elastic member 19a only needs to be placed at least on the side of the tensile force applied to the column base, and does not need to be placed around the entire circumference of the column base. For example, when considering the force from the brace 17, the elastic member 19a may be arranged in the direction in which the brace 17 is arranged. For example, in the example shown in FIG. 3, the braces 17 are arranged on both sides of the column 3, but in this case, the elastic members 19a may be arranged only in the direction in which the braces 17 are arranged.

In this way, the elastic member 19b is arranged so as to surround the entire circumference of the column base, but the elastic member 19a only needs to be arranged in the direction in which rotational deformation is expected. That is, it is not necessary to arrange the elastic member 19a in a direction in which rotational deformation is not expected or in a direction in which rotational deformation is restricted.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not limited to the embodiments described above. It is clear that those skilled in the art can come up with various changes and modifications within the scope of the technical idea stated in the claims, and these naturally fall within the technical scope of the present invention. It is understood that it belongs.

1, 1a, 1b...... Column base structure 3... Column bodies 5, 5a... Base plate 7... Mortar 9... Anchor bolt 11... Foundation 13... Slab concrete 15... Filled concrete 17...Brace 19a, 19b...Elastic member 21...Slit 23...Easy deformation part 100...Structure 101...Column 103...Foundation 105...Beam

Claims (4)

a column base having a column body and a base plate joined to the lower end of the column body;
a foundation to which the base plate is fixed;
Filler concrete provided around the column base;
Equipped with
A column base structure characterized in that an elastic member capable of compressive deformation is disposed at least partially between the filling concrete and the foundation and between the filling concrete and surrounding slab concrete. The base plate is
A hole through which an anchor bolt is inserted;
a slit formed at least partially around the hole;
Equipped with
The column pedestal structure according to claim 1, wherein a portion surrounded by the slit functions as an easily deformable portion. 2. The column pedestal structure according to claim 1, wherein the elastic member disposed between the filling concrete and the foundation is disposed over the entire circumference of the column pedestal in plan view. The column pedestal structure according to claim 1, wherein the elastic member disposed between the filling concrete and the foundation is not disposed on at least one side of the column pedestal in a circumferential direction in a plan view.

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