JP2018159190A - Column base structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a column base structure capable of preventing concrete on a base plate and concrete outside a base plate continuing to the concrete from hindering the rotational deformation of a base plate.SOLUTION: A column base structure 1 includes a column body 3, a base plate 5 joined to a lower end of the column body 3, a frame body 6 arranged along at least a part of the outer periphery of the base plate 5 and extending above the base plate 5, and concrete 4 provided on both sides of the frame body 6. When a bending moment is generated in the vertical plane on the columnar body 3 and the base plate 5 tries to rotate, the concrete 4 on the frame body 6 is prone to cracking, and concrete 4 on the base plate 5 and concrete 4 continuous to the outside of the base plate are divided by a crack.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a column base structure.

  In a joint portion between a pillar such as a steel column and a foundation, it is common to fix a base plate joined to the lower end of the pillar with an anchor bolt (for example, Patent Document 1).

  In such a column base structure, it is necessary to secure a sufficient rigidity at the above-mentioned joint portion to withstand a bending moment in a vertical plane generated in the column body during an earthquake or the like, which causes an increase in cost. On the other hand, in Patent Document 2, when the bending moment is generated in the column body, the base plate is allowed to rotate and the above-mentioned joint portion is made to behave like a pin structure, thereby reducing the proof stress required at the joint portion. However, an example in which the cost is low is described.

JP 2013-64244 A JP 2016-223070

  In such a column base structure, from the viewpoint of improving aesthetics, concrete may be provided on the foundation to a higher level than the base plate so that the base plate cannot be directly seen.

  However, in such a case, there is a problem in that the rotational deformation of the base plate is hindered by the binding force between the concrete on the base plate and the concrete outside the base plate continuous with the concrete, and the above-described effects cannot be achieved.

  The present invention has been made in view of the above problems, and an object thereof is to provide a column base structure capable of preventing the concrete on the base plate and the concrete outside the base plate continuous with the concrete from hindering the rotational deformation of the base plate. And

  The present invention for solving the aforementioned problems includes a column, a base plate joined to a lower end of the column, and a plate member disposed along at least a part of the outer periphery of the base plate and extending above the base plate. And a concrete structure provided on both sides of the plate member.

  In the present invention, the base plate is covered with concrete, and at the same time, the concrete on the base plate and the concrete on the outside thereof can be divided by providing the above plate material. This prevents the concrete on the base plate and the concrete outside the base plate continuous with the concrete from hindering the rotational deformation of the base plate, and smoothly rotates and deforms the base plate when a vertical bending moment is generated in the column. Can be made.

It is preferable that there is a gap between the base plate and a base below the base plate, and the plate material extends also below the base plate.
By providing a gap below the base plate, the amount of rotational deformation of the base plate can be increased, but at this time, the above plate material can prevent the concrete from entering the gap.

The concrete is provided up to a level higher than the upper end of the plate material, for example.
In this case, when a bending moment is generated in the column and the base plate is rotationally deformed, a crack is generated in the concrete on the plate material, so that the concrete on the base plate and the concrete on the outside can be divided.

It is desirable that the plate material is not fixed to the base plate.
In this way, the plate material is not fixed to the base plate but only disposed along the outer periphery of the base plate, so that the plate material does not hinder the rotational deformation of the base plate. “The plate is not fixed to the base plate” means that the base plate can be displaced independently of the plate. The plate is lightly held on the base plate with tape or the like so that the plate does not substantially affect the displacement of the base plate. This case is also included.

  According to the present invention, it is possible to provide a column base structure capable of preventing the concrete on the base plate and the concrete outside the base plate continuous with the concrete from hindering the rotational deformation of the base plate.

The figure which shows the column base structure 1. FIG. The figure shown about the division | segmentation of the concrete 4 by the frame 6. FIG. The figure which shows the construction method of the column base structure 1. FIG. The figure which shows the column base structure 1a. The figure which shows another example of the range of the slits 53e and 53f and the mortar 9. FIG. The figure which shows column base structure 1a '. The figure which shows the column base structure 1b. The figure which shows the column 3c and the slits 53h and 53i.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
(1. Column base structure 1)
FIG. 1 is a view showing a column base structure 1 according to a first embodiment of the present invention. FIG. 1A is a view showing a vertical section of the column base structure 1, and FIG. 1B is a view of the upper surface of the base plate 5. Fig.1 (a) is a cross section along line AA of FIG.1 (b), and illustration of the concrete 4 is abbreviate | omitted in FIG.1 (b).

  The column base structure 1 is provided on a concrete foundation 2 and includes a column body 3, concrete 4, a base plate 5, a frame body 6 (plate material), and the like. In this column base structure 1, when a bending moment in a vertical plane is generated in the column body 3, the base plate 5 is rotationally deformed, so that the joint portion between the column body 3 and the foundation 2 functions as a pin structure.

  The column 3 is a prism, for example, and is formed from a square steel pipe or the like. A base plate 5 is joined to the lower end of the column 3. The base plate 5 is a steel plate-like member having a substantially rectangular plane, and the column body 3 is joined near the center. The base plate 5 is provided with a through hole 51 and slits 53a and 53b. The slits 53a and 53b are formed avoiding the position of the column 3.

  Anchor bolts 7 are embedded in the foundation 2. The upper end portion of the anchor bolt 7 protrudes from the foundation 2 and is inserted into the through hole 51 of the base plate 5. A nut 8 is fastened to the protruding portion of the anchor bolt 7 protruding from the through hole 51. For example, a double nut is used as the nut 8, but is not limited thereto.

  The through hole 51 is disposed at a position corresponding to the center of each outer side of the base plate 5 in the vicinity of the outer periphery of the base plate 5. As shown in FIG. 1B, the anchor bolt 7 is passed through each of the through holes 51, and the nut 8 is tightened.

  The slits 53a, 53b are cut in directions different from each other in the vicinity of each anchor bolt 7, and are formed so as to be substantially L-shaped. That is, the slit 53 a is cut inward from each outer side of the base plate 5. The slit 53b is formed so as to extend in parallel with each outer side of the base plate 5 from the tip of the slit 53a. Each anchor bolt 7 (through hole 51) is surrounded by the slits 53a and 53b and the outer side of the base plate 5 from three directions.

  Since the anchor bolt 7 is surrounded by the slits 53 a and 53 b and the outer side of the base plate 5, the easily deformable portion a is formed on the base plate 5 fixed by the anchor bolt 7. In the present embodiment, the easily deformable portion a is formed between the tip of the slit 53 b and the outer side of the base plate 5. The easily deformable portion a is a portion where the base plate 5 is easily deformed, and thereby, the rotational deformation of the base plate 5 when a bending moment is generated in the column 3 can be promoted with a simple configuration. However, the slits 53a and 53b can be omitted.

  A mortar 9 is provided between the base plate 5 and the foundation 2. The mortar 9 is provided to support the base plate 5 when the column body 3 is erected.

  The mortar 9 is disposed in the vicinity of the center portion of the base plate 5, and a gap 20 is formed between the base plate 5 and the foundation 2 below the outer side of the base plate 5. Thereby, the amount of rotational deformation of the base plate 5 can be increased with a simple configuration. Note that an elastic member such as a sponge may be disposed in the gap 20.

  The frame body 6 is a plate material installed on the foundation 2 along the outer periphery of the base plate 5 so as to surround the entire periphery of the base plate 5. The frame body 6 has a substantially rectangular planar shape that matches the planar shape of the base plate 5.

  The frame body 6 is disposed so that the base plate 5 is positioned at an intermediate portion in the height direction. That is, the frame body 6 is disposed so as to extend upward and downward from the base plate 5. For example, a metal plate is used for the frame body 6, but is not limited thereto. For example, it may be made of wood or may be made of resin such as polystyrene foam.

  There is a slight gap 50 between the frame body 6 and the base plate 5 (which does not allow the concrete 4 to enter, the same gap as the slits 53 a and 53 b), and the edges are cut off. The frame body 6 is not fixed to the base plate 5. For this reason, the frame body 6 does not hinder the rotational deformation of the base plate 5.

  “The frame body 6 (plate material) is not fixed to the base plate 5” means that the base plate 5 can be displaced independently of the frame body 6, and the frame body 6 is lightly fastened to the base plate 5 with a tape or the like. A case where the frame 6 does not substantially affect the displacement of the base plate 5 is also included. Further, the gap 50 may not be provided as long as the edge is cut between the frame body 6 and the base plate 5.

  Concrete 4 is provided on the foundation 2, and the concrete 4 covers the base plate 5 inside the frame body 6 and the foundation 2 outside the frame body 6. By covering the base plate 5 with the concrete 4 in this way, effects such as an improvement in aesthetics can be achieved. The concrete 4 is provided to a level higher than the upper end of the frame body 6. When a reinforcing bar is provided in the concrete 4, the reinforcing bar is prevented from interfering with the frame body 6. In addition, the concrete 4 is provided to a level that ensures the covering of the reinforcing bars.

  In the present embodiment, when a bending moment in the vertical plane is generated in the column 3 and the base plate 5 is about to rotate, cracks occur in the thin portion of the concrete 4 on the frame 6 as shown in FIG. 41 is easily generated, and the concrete 4 on the base plate 5 and the concrete 4 continuous to the outside thereof are divided by the crack 41.

  If these concretes 4 are continuous, the rotational deformation of the base plate 5 is hindered by the binding force of the continuous concrete 4, but in this embodiment, the concrete plates 4 are divided by the cracks 41, so that the base plate 5 The rotational deformation of 5 is not disturbed.

  In addition, you may make it provide the concrete 4 to the level of the upper end vicinity of the frame 6 as shown in FIG.2 (b). In this case, since the concrete 4 inside and outside the frame body 6 is divided without waiting for the generation of the crack 41, the same effect as described above can be obtained. In addition, the concrete 4 may be provided up to a level lower than the upper end of the frame 6, and in this case, the same effect can be obtained.

(2. Construction method of column base structure 1)
Next, the construction method of the column base structure 1 will be described. In this embodiment, first, as shown in FIG. 3A, the mortar 9 is installed on the foundation 2, and the base plate 5 is arranged thereon. The base plate 5 is arranged by inserting the upper end portion of the anchor bolt 7 protruding from the foundation 2 into the through hole 51. The column body 3 is joined to the upper surface of the base plate 5.

  Next, as shown in FIG. 3 (b), the base plate 5 is fixed to the base 2 by the anchor bolt 7 by tightening the nut 8 into the protruding portion of the anchor bolt 7 protruding from the base plate 5. Then, the frame 6 is installed on the foundation 2.

  Thereafter, as shown in FIG. 1A, the concrete 4 is placed on the base plate 5 inside the frame body 6 and on the foundation 2 outside the frame body 6. At this time, the frame 6 prevents the concrete 4 from entering the gap 20 between the base plate 5 and the foundation 2. The concrete 4 is cast to a level higher than the upper end of the frame body 6, thereby forming the column base structure 1 described above.

  As described above, according to the column base structure 1 of the present embodiment, the base plate 5 is covered with the concrete 4 and at the same time, the concrete on the base plate 5 and the concrete 4 on the outside of the base plate 5 are provided by providing the frame body 6 (plate material). Can be divided. This prevents the concrete 4 on the base plate 5 and the concrete 4 outside the base plate 5 continuous with the concrete 4 from interfering with the rotational deformation of the base plate 5, and the base plate 5 is removed when a bending moment is generated in the column 3. By smoothly rotating and deforming, the joint portion between the pillar 3 and the foundation 2 can be suitably functioned as a pin structure.

  In this embodiment, the amount of rotational deformation can be increased by providing the gap 20 below the base plate 5, but at this time, the concrete body 4 enters the gap 20 and closes the gap 20 by the frame body 6. Can be prevented.

  Further, in this embodiment, when a bending moment is applied to the column 3 and the base plate 5 is rotationally deformed, a crack 41 is generated in the concrete 4 on the frame 6, so that the concrete 4 on the base plate 5 and the concrete on the outer side thereof. 4 can be divided.

  Furthermore, in the present embodiment, the frame body 6 is not fixed to the base plate 5 but only disposed around the base plate 5, so the frame body 6 does not hinder the rotational deformation of the base plate 5.

  However, the present invention is not limited to the above embodiment. For example, the frame body 6 may be provided along only a part or only one side of the outer periphery of the base plate 5 depending on a plan plan or the like, such as a case where the column body 3 is arranged at the outer edge or corner of the building. In addition, depending on the installation method of the frame body 6, a barrier material (not shown) for preventing the concrete 4 from entering the gap 20 is provided below the base plate 5, and the frame body 6 is only above the base plate 5. It can also be shaped to extend. Furthermore, the shapes of the column 3 and the base plate 5 are not particularly limited, and the planar shape of the frame 6 may be a shape that matches the planar shape of the base plate 5.

  Hereinafter, other examples of the present invention will be described as second to fourth embodiments. Each embodiment will explain different points from the embodiments described so far, and description of similar points will be omitted. In addition, the configurations described in each embodiment including the first embodiment can be used in combination as necessary.

[Second Embodiment]
FIG. 4 is a view showing a column base structure 1a according to a second embodiment of the present invention. 4A is a view showing a vertical cross section of the column base structure 1a, and FIG. 4B is a view of the upper surface of the base plate 5a. FIG. 4A is a cross section taken along line BB in FIG. 4B, and illustration of the concrete 4 is omitted in FIG. 4B.

  In 2nd Embodiment, the column 3a is a H steel pillar, and the baseplate 5a is joined to the lower end. Four through holes 51 are provided substantially at the center of the base plate 5 a, and the anchor bolts 7 are inserted into the respective through holes 51.

  The base plate 5 a is fixed to the anchor bolt 7 by being sandwiched from above and below by nuts 8 a and 8 b fastened to the anchor bolt 7. Therefore, the height of the gap 20 between the base plate 5a and the base 2 is larger than the thickness of the nut 8b below the base plate 5a.

  As shown in FIG. 4 (b), the anchor bolt 7 (through hole 51) is located inside each width with respect to the width in the vertical and horizontal directions of the plane of the column 3a, and is outside from the vertical and horizontal range of the column 3a. It doesn't stick out.

  The mortar 9 is formed in a range slightly larger than the range in which the anchor bolt 7 at substantially the center of the base plate 5a is disposed as shown by the dotted line in FIG. 4B, and the gap 20 is formed in a wide range on the outer peripheral side of the base plate 5a. Is formed. The length of the plane of the mortar 9 in the vertical and horizontal directions is, for example, in the range of 1/5 to 1/2 with respect to the length of the base plate 5a in the same direction.

  The nut 8b below the base plate 5a is not always necessary, and the base plate 5a may be provided directly on the foundation 2. In this case, the mortar 9 is unnecessary. Further, the base plate 5a may be supported only by the nuts 8a and 8b, and in this case, the mortar 9 is not necessary.

  The base plate 5a is provided with slits 53c and 53d. The slits 53c and 53d are cut in different directions, and are formed to be continuous in a substantially T shape. That is, the slit 53c is cut linearly inward from the center of the outer side on both sides of the base plate 5a with the column 3a interposed therebetween. The slit 53d is formed so as to be substantially orthogonal to the slit 53c and intersect the tip of the slit 53c.

  In the present embodiment, each anchor bolt 7 is surrounded from three directions by the slits 53c and 53d and the outer side of the base plate 5a, and the easily deformable portion a is between the tip of the slit 53d and the outer side of the base plate 5a (or , Between the tip of the slit 53d and the intersection of the slit 53c and the outer side of the base plate 5a).

  Further, in this embodiment, the anchor bolt 7 is moved as close to the center of the base plate 5a as possible so as not to protrude from the range of the column 3a, and the size (area) of the mortar 9 is reduced, thereby rotating the base plate 5a. The amount can be made larger.

  In the present embodiment, the anchor bolts 7 are arranged inside the vertical and horizontal widths of the plane of the column 3a. However, the anchor bolts 7 need only be arranged inside at least one of the widths. The anchor bolt 7 may be disposed outside the mortar 9.

  Furthermore, the arrangement of the slits is not limited to the above. For example, as shown in FIG. 5A, slits 53e and 53f that are not continuous with the outer side of the base plate 5a may be provided. The slits 53e and 53f are cut in different directions and are formed to be substantially E-shaped. That is, three slits 53e are formed in parallel to each other on both sides of the column 3a of the base plate 5a. One slit 53f is formed so as to be substantially orthogonal to the three slits 53e and to intersect the front ends of the slits 53e on the column body 3a side.

  The anchor bolt 7 is disposed between adjacent slits 53e, and is surrounded by these slits 53e and 53f from three directions. In this case, an easily deformable portion a that connects the distal ends of the slit 53e on the outer side of the base plate 5a is formed. The slits 53e on both sides of the three slits 53e may be omitted. In this case, the anchor bolt 7 is surrounded by the remaining central slit 53e and slit 53f, and the tip of the slit 53f and the base plate 5a of the slit 53e. An easy-to-deform portion is formed between the outer edge side of each of the two.

  In this way, in order to form the easily deformable portion, the anchor bolt 7 may be surrounded from a plurality of directions by continuous slits in different directions. Alternatively, the anchor bolt 7 may be surrounded from a plurality of directions by a slit formed in at least one direction and an outer side of the base plate that is continuous with the slit and has a direction different from the slit. As described above, the easily deformable portion can be formed by surrounding the anchor bolt 7 from at least two directions (preferably three or more directions) with only the slit or with the slit and the outer side of the base plate.

  Further, as shown in FIG. 5 (b), the mortar 9 does not necessarily have to be arranged only in the center as long as it is smaller than the size of the base plate 5a. In the example of FIG. 5B, the length in one direction (vertical direction in the drawing) of the plane of the mortar 9 is substantially the same as the length of the base plate 5a in that direction. Also in this case, a gap 20 can be formed between the base plate 5a and the foundation 2.

[Third embodiment]
FIG. 6 is a view showing a column base structure 1a ′ according to a third embodiment of the present invention. This column base structure 1 a ′ differs from the column base structure 1 a of the second embodiment in that a metal plate 10 is provided under the mortar 9. The metal plate 10 is, for example, a steel plate or a stainless steel plate. The thickness of the mortar 9 is, for example, about 50 mm, and the thickness of the metal plate 10 is, for example, about 5-30 mm, but is not limited thereto.

  Here, the mortar 9 and the concrete of the foundation 2 have substantially the same elastic rigidity. Usually, the strength of the mortar 9 is larger than the strength of the concrete of the foundation 2. Furthermore, in this embodiment, since the size of the mortar 9 is small and the bearing area is small, a large compressive stress is applied to the concrete of the foundation 2. For this reason, when the compression axial force which acted on the column 3 is transmitted to the foundation 2 via the mortar 9, there is a possibility that the concrete of the foundation 2 may be destroyed.

  On the other hand, in this embodiment, by arranging the metal plate 10 between the mortar 9 and the foundation 2, the compressive fracture strength of the concrete of the foundation 2 can be improved by the local bearing effect.

  The local bearing effect means that the bearing area (area that gives force to the concrete) is smaller than the bearing area (concrete area that the force from the bearing area exerts) and the concrete is subjected to local compression. It means that concrete strength that is several times the original is generated in concrete that receives direct force from the bearing area due to the restraining effect from concrete. In order to effectively obtain such a local bearing effect, it is necessary that a member for applying a force to the concrete has sufficiently larger elastic rigidity than the concrete.

  In this embodiment, since the metal plate 10 having a large elastic rigidity is disposed between the mortar 9 and the concrete of the foundation 2, the local bearing effect can be obtained efficiently, and the size of the mortar 9 can be reduced. Can also suppress the destruction of the concrete of the foundation 2.

  In the present embodiment, the length in the vertical and horizontal directions of the plane of the metal plate 10 is about the same as that of the mortar 9, but the length in either direction or both directions is about the thickness of the metal plate 10 and larger than the mortar 9. May be. However, the length of the plane of the metal plate 10 in the vertical and horizontal directions is not limited to these, and can be increased to, for example, the range of the base plate 5a (however, the local bearing effect does not change). Further, the top and bottom of the metal plate 10 and the mortar 9 may be interchanged.

  As described above, the mortar 9 is provided substantially at the center of the base plate 5a, and the length of at least one direction of the plane of the mortar 9 is in the range of 1/5 to 1/2 of the length of the base plate 5a in that direction. It is desirable that If the size of the mortar 9 is too small, the bearing area from the mortar 9 to the foundation 2 with respect to the compression axial force from the column 3 becomes too small, which is not desirable. If the size of the mortar 9 is too large, the amount of rotational deformation of the base plate 5a is reduced.

[Fourth Embodiment]
FIG. 7 is a view showing a column base structure 1b according to a fourth embodiment of the present invention. FIG. 7A is a view showing a vertical cross section of the column base structure 1b, and FIG. 7B is a view of the upper surface of the base plate 5b. Fig.7 (a) is a cross section along line CC of FIG.7 (b), and illustration of the concrete 4 is abbreviate | omitted in FIG.7 (b).

  In the column base structure 1b, the column 3b is a prism, and a notch 31 is formed therebelow. As shown in FIG. 7B, the notches 31 are provided on each of a pair of opposing sides of the plane of the column 3b, and a slit 53g is formed at a portion of the base plate 5b corresponding to the notch 31. Thereby, the slit 53g can be formed avoiding the position of the column 3b.

  The slits 53g are cut inward from the outer side of the base plate 5b, and are formed in parallel. Anchor bolts 7 are arranged in a region surrounded by the slits 53g and the outer side of the base plate 5b. The anchor bolts 7 are disposed at a total of two locations, and each anchor bolt 7 is surrounded by the two slits 53g described above and the outer side of the base plate 5b that is continuous with the slits 53g and in a direction different from the slits 53g. In this case, the easily deformable portion a is formed between the ends of the two slits 53g.

  The column body 3b is not limited to a rectangular column and may be a cylinder. Even in this case, by providing the same notch 31 as described above, the slit 53g can be formed while avoiding the position of the column 3b.

  In addition, as shown in FIG. 8, slits 53h and 53i that are not continuous with the outer side of the base plate 5b may be formed inside a columnar body 3c such as a prism without a notch. These slits 53h and 53i intersect substantially orthogonally and are formed in a substantially X shape.

  The anchor bolts 7 are respectively arranged at four locations partitioned by the slits 53h and 53i, and are surrounded by continuous slits 53h and 53i in different directions. In this case, the easily deformable portion a is formed between the tips of the slits 53h and 53i, and the region surrounding the anchor bolt 7 between the easily deformable portion a and the slits 53h and 53i is triangular.

  Thus, the region surrounding the anchor bolt 7 by the easily deformable portion and the slit need not be rectangular, and the slit need not be parallel or perpendicular to the outer side of the base plate. In addition, the slit need not be linear and may be arcuate. Even in this case, one arc-shaped slit is a continuous slit in different directions. That is, it is only necessary that the anchor bolt is surrounded from a plurality of directions by one continuous arc-shaped slit in different directions.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

1, 1a, 1a ′, 1b: column base structure 2: foundation 3, 3a, 3b, 3c: column body 4: concrete 5, 5a, 5b: base plate 6: frame body 7: anchor bolts 8, 8a, 8b: nuts 9: Mortar 10: Metal plate 20, 50: Gap 31: Notch 41: Crack 51: Through hole 53a to 53i: Slit

Claims (4)

The column,
A base plate joined to the lower end of the pillar,
A plate member disposed along at least a part of the outer periphery of the base plate and extending above the base plate;
Concrete provided on both sides of the plate,
Column base structure characterized by comprising. There is a gap between the base plate and the base below the base plate,
The column base structure according to claim 1, wherein the plate member also extends below the base plate.   The column base structure according to claim 1, wherein the concrete is provided up to a level higher than an upper end of the plate member.   The column base structure according to any one of claims 1 to 3, wherein the plate member is not fixed to the base plate.

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