Column base connection structure

Abstract

To provide a column base joint structure of a pin joint in which falling prevention at the time of a column rotation is guaranteed.SOLUTION: In a column base joint structure 100 for a reinforced-concrete column 10 and a base 20, the column 10 is placed on the base 20 in a state of being edge-cut so as to rotate with respect to the base 20, and a plurality of pressing materials 30 or one continuous pressing material fixed to the base 20 presse a plurality of places of or the whole periphery of a side surface 11 at a lower part of the column 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a column base joint structure.

Background Art

[0002] In a building made of reinforced concrete, by rigidly joining a column to a foundation such as a foundation base, footing, foundation beam, or pile, while the effect of suppressing deformation at the joint between the column base and the foundation is achieved, due to the rigid joint, the bending moment generated at the joint between the column base and the foundation generally becomes large, and it becomes necessary to arrange steel bars that can resist this bending moment in a dense manner. Therefore, there are problems from the viewpoints of constructability and construction cost (material cost).

[0003] Regarding the problems of the column base joint structure by this rigid joint, by pin-joining the column base and the foundation, since rotation at the joint between the column base and the foundation is allowed and no bending moment is generated, over-dense reinforcement at the joint is eliminated, and it becomes possible to solve the above-mentioned problems in constructability and construction cost included in the rigid joint structure. In a building structure having a pin-jointed column base joint structure, a brace structure or a truss structure is generally applied.

[0004] Here, Patent Documents 1 and 2 propose a column base joint structure of a building having a plurality of layers in which the flexural strength is reduced to avoid stress concentration on the lowermost layer and the reduction of other strengths is suppressed. The column base joint structure described in Patent Document 1 includes a reinforced concrete foundation structure, a first column bar erected on the foundation structure, connected to the foundation structure, and extending in the vertical direction, a reinforced concrete column having a second column bar extending in the vertical direction without being connected to the foundation structure, and a thin film or plate-shaped edge-cutting member disposed at least partially between the foundation structure and the column.

[0005] On the one hand, the column base joint structure described in Patent Document 2 includes a foundation structure of reinforced concrete, a first column bar that is erected on the foundation structure, connected to the foundation structure, and extends in the vertical direction, and a second column bar that extends in the vertical direction without being connected to the foundation structure. A column made of reinforced concrete having a fitting member disposed at least partially between the foundation structure and the column, and the fitting member is formed of a composite structure of rubber and a steel plate.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In both of the column base joint structures described in Patent Documents 1 and 2, since a part of the column bars is buried and joined to the foundation, it is not possible to form a pin joint (or a complete pin joint) column base joint structure, and it becomes a so-called semi-rigid joint column base joint structure. Therefore, a bending moment will inevitably occur at the joint between the column base and the foundation. Compared with the pin joint column base joint structure, the amount of reinforcement at the joint increases, and it is inevitably disadvantageous in terms of both constructability and construction cost.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide a column base joint structure that is a pin joint and ensures prevention of collapse when the column rotates.

Means for Solving the Problems

[0009] To achieve the above object, one aspect of the column base joint structure according to the present invention is a column base joint structure of a column and a foundation made of reinforced concrete, wherein the column is placed on the foundation in a state of being cut off from the foundation so as to be rotatable. A plurality of pressing members fixed to the foundation or a continuous single pressing member presses a plurality of locations or the entire circumference of the lower side surface of the column.

[0010] According to this aspect, since the column is placed on the foundation in a state where it is rotatably separated from the foundation, a column base joint structure with pin joints (complete pin joints) can be formed. With the pin joint column base joint structure, no bending moment is generated at the joint between the column base and the foundation. Therefore, over-dense reinforcement in the column base and the foundation can be prevented. Furthermore, since there is no fixing of the column bars to the foundation, good constructability can be enjoyed.

[0011] Furthermore, by a plurality of pressing members fixed to the foundation pressing a plurality of locations on the lower side surface of the column, or a continuous single pressing member pressing the entire circumference of the lower side surface of the column, it is possible to prevent the lateral collapse of the column that is rotatable with respect to the foundation. Also, the pressing member can bear (receive) the horizontal reaction force generated at the pin support point.

[0012] Here, the foundation made of reinforced concrete includes various forms of foundations such as a foundation base plate, a foundation pedestal, a footing, and a foundation beam. Also, the column includes various forms of columns such as a prismatic column with a rectangular cross-section (square or rectangular) or a polygonal cross-section other than rectangular, a cylindrical column, and an elliptical column.

[0013] The pressing member is a member having rigidity capable of supporting the column from the side, such as a shaped steel material like a channel steel or an H-shaped steel, a frame body made of a plurality of shaped steel materials, or a reinforced concrete member, and is fixed to, for example, the upper surface of the foundation via an anchor bolt or the like. For example, there are forms in which specific pressing members are arranged at positions corresponding to each side surface of a prismatic column with a polygonal cross-section to press the corresponding side surface from the side, or forms in which the entire circumference of a cylindrical column is pressed from the side by an annular continuous pressing member arranged around it.

[0014] Moreover, another aspect of the column base joint structure according to the present invention is A support block, which has a smaller planar dimension than the column and is formed of concrete with higher strength than the column, is fixed to the upper surface of the foundation, and the column is placed on the support block.

[0015] According to this aspect, since a support block having a smaller planar dimension than the column is fixed to the upper surface of the foundation and the column is placed on the support block, smooth rotation of the column can be realized when, for example, a horizontal force acts on the column during an earthquake. Further, since the support block has a smaller dimension than the column, by forming the support block of concrete having higher strength (higher compressive strength) than the column, crushing of the support block can be prevented against the axial force acting on the support block from the column at all times and during an earthquake.

[0016] Further, in another aspect of the column base joint structure according to the present invention, the support block has a prismatic shape, and corners above the support block are chamfered.

[0017] According to this aspect, in the prismatic support block, by chamfering the corners including the upper corners thereof, it is possible to suppress the concentration of the load from the column on the corners of the support block and the breakage of the corners when the column rotates. Here, the chamfered form includes a tapered surface form, a curved surface form, a form in which a tapered surface and a curved surface are continuous, and the like.

[0018] Further, in another aspect of the column base joint structure according to the present invention, a sliding material is attached to at least one of the upper surface of the support block and the lower surface of the column.

[0019] According to this aspect, by attaching a sliding material to at least one of the upper surface of the support block and the lower surface of the column, smoother rotation of the column can be achieved. Here, "at least one of the upper surface of the support block and the lower surface of the column" includes both the upper surface of the support block and the lower surface of the column, only the upper surface of the support block, and only the lower surface of the column.

[0020] Further, in another aspect of the column base joint structure according to the present invention, a spherical seat made of steel and having a surface to be rotated is placed on the upper surface of the foundation or embedded inside from the upper surface of the foundation, a rotating body made of steel and having a rotating surface with a complementary shape to the surface to be rotated is attached to the lower surface of the column, and the rotating body is rotatably fitted into the spherical seat, and the column is placed on the spherical seat.

[0021] According to this aspect, a spherical seat made of steel and having a surface to be rotated is placed or the like on the upper surface of the foundation, and a rotating body made of steel and having a rotating surface with a complementary shape to the surface to be rotated, which is attached to the lower surface of the column, is rotatably fitted into the spherical seat. Thus, direct sliding between the reinforced concrete column and the foundation is eliminated, the durability of both sliding parts is enhanced, and smooth rotation of the column with respect to the foundation can be realized.

[0022] Further, another aspect of the column base joint structure according to the present invention is an elastic body is attached to the pressing member, and the elastic body presses the side surface of the column.

[0023] According to this aspect, since the elastic body attached to the pressing member directly presses the side surface of the column, when a horizontal force acts on the column and the column rotates, the pressing reaction force acting on the column is relaxed due to the deformation performance of the elastic body. Therefore, it is possible to prevent the side surface of the column from being damaged by receiving the pressing reaction force from the hard pressing member.

[0024] Further, another aspect of the column base joint structure according to the present invention is The column is rectangular in plan view and has four side surfaces, The pressing member is disposed at a position corresponding to each of the side surfaces or at the entire circumferential position of the side surface, and presses the four side surfaces.

[0025] According to this aspect, in a column having a rectangular shape in plan view (cross-sectional shape), which is the most common column shape in plan view, each side surface is pressed laterally by a specific pressing member corresponding to each of the four side surfaces or a pressing member continuous over the entire circumference of the four side surfaces. Therefore, no matter in which direction the column rotates 360 degrees in plan view, the column can be prevented from falling by being pressed by the pressing member.

Advantages of the Invention

[0026] As can be understood from the above description, according to the column base joint structure of the present invention, a column base joint structure that is a pin joint and ensures prevention of falling during rotation of the column can be provided.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0028] Hereinafter, an example of the column base joint structure according to each embodiment will be described with reference to the accompanying drawings. In the present specification and drawings, substantially the same components may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0029] [Column Base Joint Structure According to the First Embodiment] First, with reference to FIGS. 1 to 3, an example of the column base joint structure according to the first embodiment will be described. Here, FIG. 1 is a longitudinal sectional view of an example of the column base joint structure according to the first embodiment, and FIG. 2 is a view taken in the direction of arrow II-II in FIG. 1. Further, FIG. 3 is a view for explaining a state in which a horizontal force acts on the column forming the column base joint structure according to the first embodiment and the column is rotating.

[0030] The column base joint structure 100 between the reinforced concrete column 10 and the foundation 20 is formed by placing the lower surface 12 of the column 10 in a state of being cut off so as to be rotatable in the X1 direction within a vertical plane with respect to the 360-degree direction in the plan view of the upper surface 21 of the foundation 20 as shown in the figure. With this configuration, a pin joint (full pin joint) column base joint structure is formed, and no bending moment is generated at the joint between the lower surface 12 of the column 10 and the upper surface 21 of the foundation 20.

[0031] The column 10 in the illustrated example is square in plan view (an example of a rectangle), and the lower ends of the column main reinforcements 15 are positioned at positions where a predetermined cover is ensured from the lower surface 12 of the column 10. Further, a plurality of hoop bars 16 are arranged around the plurality of column main reinforcements 15 at a predetermined pitch in the longitudinal direction of the column 10.

[0032] The foundation 20 in the illustrated example is, for example, a foundation base plate, and has a plurality of upper end main reinforcements 25 orthogonal to each other upward and a plurality of lower end main reinforcements 26 orthogonal to each other downward. Here, the foundation may be a footing, a foundation beam, or the like in addition to the bottom plate in the illustrated example.

[0033] On the upper surface 21 of the foundation 20, a support block 50 is fixed, which is formed of high-strength concrete having a smaller planar dimension than the column 10 having a square shape in plan view and a higher compressive strength than the column 10. For example, with respect to the design reference strength of the column 10 being 24 N / mm2, by applying a support block 30 having a design reference strength of, for example, 27 N / mm2, 30 N / mm2, etc., and desirably 50 N / mm2 or more, crushing, etc. of the support block 30 having a relatively small planar dimension can be prevented.

[0034] The support block 50 has a prismatic shape, and its upper corners (four side edges and four corner portions) are chamfered. Here, although the chamfered portion 54 in the illustrated example is formed by a tapered surface, it may be formed by a curved surface.

[0035] Furthermore, a sliding material 58 is attached to the flat top surface of the support block 50. Here, as the sliding material 58, a plate made of stainless steel (SUS), a fabric such as PTFE fiber (polytetrafluoroethylene), etc. can be applied.

[0036] In the illustrated example, the sliding material 58 is attached only to the top surface of the support block 50, but for example, a sliding material may be attached to the lower surface 12 of the column 10, or sliding materials may be attached to both the top surface of the support block 50 and the lower surface 12 of the column 10.

[0037] The foundation 20 is provided with fixing holes 23 extending from its upper surface 21 to the inside. And fixing bars 52 embedded inside the support block 50 and protruding downward from the lower surface are disposed in the fixing holes 23, and by filling the fixing holes 23 with non-shrink mortar 53 (an example of a filling material), the support block 50 is firmly fixed to the upper surface 21 of the foundation 20.

[0038] The lower surface 12 of the column 10 is placed on the sliding material 58 on the top surface of the support block 50. In this way, by placing the column 10 on the sliding material 58, when a horizontal force H acts on the column 10 during an earthquake as shown in Fig. 3, the column 10 can smoothly rotate in the X2 direction on the support block 50. Here, the horizontal force H acts not only during general-scale earthquakes or large earthquakes but also during strong winds such as typhoons.

[0039] Furthermore, since the upper corners of the support block 50 are chamfered, when the column 10 rotates in the X2 direction as shown in Fig. 3, it is possible to prevent the concentrated load from acting on the corners of the support block 50 from the lower surface 12 of the column 10 and damaging the corners.

[0040] Although the column 10 can be pin-jointed to the joint between the column 10 and the foundation 20 by placing the column 10 on the upper surface of the support block 50, this configuration alone cannot maintain the stable posture of the column 10 supported by the support block 50.

[0041] Therefore, in the column base joint structure 100, a plurality of pressing members 30 press a plurality of locations on the lower side surface 11 of the column 10 to prevent the column 10, which is rotatable with respect to the foundation 20, from falling sideways.

[0042] The pressing member 30 is an L-shaped steel block or a reinforced concrete block in side view. One piece of it is placed on the upper surface 21 of the foundation 20 and fixed to the foundation 20 via anchor bolts 35.

[0043] As clearly shown in Fig. 2, the pressing members 30 are arranged at positions corresponding to each of the four side surfaces 11 of the column 10 that is square in plan view, and the four side surfaces 11 of the column 10 are pressed by the four pressing members 30. Here, in addition to the illustrated example, a form in which a pressing member continuous in a square frame shape presses the entire circumferential side surface 11 of the column 10 may also be used.

[0044] Also, in the illustrated example, instead of the pressing member 30 directly pressing against the side surface 11 of the column 10, the side surface 11 of the column 10 is pressed via the elastic body 40. Here, the elastic body 40 can be formed of a resin member such as rubber, a woven fabric, a cloth, or the like.

[0045] In this way, since the elastic body 40 attached to the pressing member 30 directly presses against the side surface 11 of the column 10, when a horizontal force H acts on the column 10 as shown in FIG. 3 and the column 10 rotates in the X2 direction, it is possible to prevent the side surface 11 of the column 10 from receiving a pressing reaction force from the rigid pressing member 30 against the pushing forces P1 and P2 acting from the side surface 11 of the column 10 and being damaged. That is, the pushing forces P1 and P2 acting from the side surface 11 of the column 10 in this way are absorbed by the deformation performance of the elastic body 40, so that an excessive pressing reaction force does not act on the side surface 11 of the column 10.

[0046] Furthermore, since the elastic body 40 having deformation performance presses against the side surface 11 of the column 10, it is possible to prevent the column 10 from falling while pressing against the side surface 11 of the column 10 in a manner that does not inhibit the rotation of the column 10.

[0047] As shown in FIG. 3, when a horizontal force H during an earthquake acts on the column 10 and the column 10 rotates in the X2 direction with the support block 50 on the upper surface 21 of the foundation 20 as a fulcrum, the horizontal reaction force S is transmitted to the foundation through the pressing member 30 that receives the pushing forces P1 and P2 and through the anchor bolt 35 that fixes the pressing member 30 to the foundation 20.

[0048] According to the column base joint structure 100, since the column 10 is placed on the foundation 20 via the support block 50 in a state where it is freely rotatable and separated from the foundation 20, a column base joint structure 100 with a pin joint (complete pin joint) can be formed. With the pin joint column base joint structure 100, no bending moment is generated at the joint between the column base and the foundation. Therefore, over-dense reinforcement in the column base and the foundation can be prevented. Furthermore, since the column main reinforcement 15 is not fixed to the foundation 20, the workability is improved.

[0049] Furthermore, a plurality of pressing members 40 fixed to the foundation 20 press against a plurality of locations on the lower side surface 11 of the column 10, thereby effectively preventing the lateral collapse of the rotatable column 10 with respect to the foundation 20 while forming a full pin joint at the joint between the column 10 and the foundation 20.

[0050] [Column base joint structure according to the second embodiment] Next, with reference to FIGS. 4 and 5, an example of the column base joint structure according to the second embodiment will be described. Here, FIG. 4 is a longitudinal sectional view of an example of the column base joint structure according to the second embodiment, and FIG. 5 is a view taken in the direction of arrow V in FIG. 4.

[0051] In the column base joint structure 100A, a spherical seat 60 made of steel and having a surface to be rotated 62 is embedded inside from the upper surface 21 of the foundation 20. On the lower surface 12 of the column 10, a steel rotating body 70 having a rotating surface 72 with a complementary shape to the surface to be rotated 62 is attached. The rotating body 70 is rotatably fitted into the spherical seat 60 in the X2 direction, and the column 10 is placed on the spherical seat 60.

[0052] A plurality of fixing dowels 76 are welded to the upper surface 74 of the rotating body 70, and the plurality of fixing dowels 76 are fixed inside from the lower surface 12 of the column 10.

[0053] According to the column base joint structure 100A, the rotating surface 72 of the steel rotating body 70 is rotatably fitted into the surface to be rotated 62 of the steel spherical seat 60, and since the surface to be rotated 62 and the rotating surface 72 have complementary shapes, direct sliding between the reinforced concrete column 10 and the foundation 20 can be eliminated, and the durability of both sliding parts can be enhanced. Furthermore, smooth and stable rotation of the column 10 with respect to the foundation 20 can be realized.

[0054] Although not shown, a form in which the spherical seat has a surface to be rotated that is convex upward and the rotating surface of the steel rotating body is concave upward, that is, a form having a spherical seat and a rotating body with an uneven state opposite to the illustrated example may also be used.

[0055] [Column base joint structure according to the third embodiment] Next, with reference to FIGS. 6 and 7, an example of a column base joint structure according to the third embodiment will be described. Here, FIG. 6 is a longitudinal sectional view of an example of the column base joint structure according to the third embodiment, and FIG. 7 is a view taken in the direction of arrow VII in FIG. 6.

[0056] The column base joint structure 100B is different from the column base joint structure 100A in that a spherical seat 60A made of steel and having a surface to be rotated 62 is placed on the upper surface 21 of the foundation 20.

[0057] The spherical seat 60A is fixed to the foundation 20 by anchor bolts 35 together with a pressing member 30. Further, on the lower surface 12 of the column 10, a rotating body 70A having a rotating surface 72 with a shape complementary to the surface to be rotated 62 of the spherical seat 60A is fixed via a plurality of fixing dowels 76.

[0058] Also in the column base joint structure 100B, the rotating surface 72 of the rotating body 70A made of steel is rotatably fitted into the surface to be rotated 62 of the spherical seat 60A made of steel in the same manner, and since the surface to be rotated 62 and the rotating surface 72 are complementary in shape, direct sliding between the reinforced concrete column 10 and the foundation 20 can be eliminated, and the durability of both sliding portions can be enhanced. Further, smooth and stable rotation of the column 10 with respect to the foundation 20 can be realized.

[0059] Other embodiments in which other components are combined with the configurations and the like described in the above embodiments may be possible, and the present invention is not limited to the configurations shown here at all. In this regard, it can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form.

Explanation of Reference Numerals

[0060] 10: Column 11: Side surface 12: Lower surface 15: Main column reinforcement 16: Stirrup 20: Foundation 21: Upper surface 23: Fixing hole 25: Upper end main reinforcement 26: Lower end main reinforcement 30: Pressing material 35: Anchor bolt 40: Elastic body 50: Support block 52: Fixing reinforcement 53: Non-shrinking mortar 54: Chamfered part 58: Sliding material 60,60A: Ball seat 62: Rotating surface 70,70A: Rotating body 72: Rotating surface 74: Upper surface 76: Fixing dibel 100,100A,100B: Column base joint structure H: Horizontal force S: Horizontal reaction force P1,P2: Pushing force

Claims

1. A column-foot joint structure for a reinforced concrete column and a foundation, A support block, which is smaller in plan dimension than the column and is formed of concrete having a higher strength than that of the column, is fixed to the upper surface of the foundation, The column is placed on the support block in a state of being circumferentially cut so as to be rotatable with respect to the foundation, A plurality of pressing members fixed to the foundation or a continuous single pressing member presses a plurality of locations or the entire circumference of the lower side surface of the column, and the column-foot joint structure is characterized by this.

2. The support block has a prismatic shape, The column-foot joint structure according to claim 1, wherein upper corners of the support block are chamfered.

3. The column-foot joint structure according to claim 1 or 2, wherein a sliding material is attached to at least one of the upper surface of the support block and the lower surface of the column.

4. A column-foot joint structure for a reinforced concrete column and a foundation, A spherical seat made of steel and having a surface to be rotated is placed on the upper surface of the foundation or embedded inside from the upper surface of the foundation, A rotating body made of steel and having a rotating surface with a shape complementary to the surface to be rotated is attached to the lower surface of the column, The rotating body is rotatably fitted into the spherical seat, and the column is placed on the spherical seat in a state of being circumferentially cut so as to be rotatable with respect to the foundation, A plurality of pressing members fixed to the foundation or a continuous single pressing member presses a plurality of locations or the entire circumference of the lower side surface of the column, and the column-foot joint structure is characterized by this.

5. The column-foot joint structure according to any one of claims 1 to 4, wherein an elastic body is attached to the pressing member, and the elastic body presses the side surface of the column.

6. The column has a rectangular shape in plan view and has four side surfaces, The column base joint structure according to any one of claims 1 to 5, characterized in that the pressing member is disposed at a position corresponding to each of the side surfaces or at the entire circumferential position of the side surface to press the four side surfaces.

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