Pile-column joint structure

Abstract

To provide a joint structure between a pile and a column requiring no footing.SOLUTION: A joint structure between a pile and a column comprises: a cast-in-place pile (pile 40); a reinforced concrete column (column 20)jointed to a pile head of the cast-in-place pile; a plurality of pile main reinforcements 42 buried in the cast-in-place pile, and having upper parts projected from the pile head and buried in the reinforced concrete column; and a plurality of reinforcement bars 26 buried in the reinforced concrete column and placed so as to surround a plurality of column main reinforcement bars when viewed from a vertical direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a joint structure between a pile and a column. [Background technology]

[0002] Patent Document 1 below shows a pile foundation structure including piles, foundation beams joined to the pile heads of the piles, footings supporting the pile heads, and columns supported by the footings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-200620 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the pile foundation structure of Patent Document 1, the main reinforcement of the column is connected to the footing, and the vertical reinforcement arranged inside the pile is connected to the footing. Therefore, the pull-out force acting on the column during an earthquake is transmitted to the pile via the footing. In other words, the pull-out force cannot be transmitted directly from the column to the pile.

[0005] In addition, in this pile foundation structure, the pile head joint pipe, which is constructed integrally with the footing, is placed on the lowered ground surface formed by excavating the ground, which requires construction time for excavating the ground.

[0006] In consideration of the above, an object of the present invention is to provide a joint structure between a pile and a column that does not require a footing. [Means for solving the problem]

[0007] The pile-column joint structure of claim 1 includes a cast-in-place pile, a reinforced concrete pillar joined to the pile head of the cast-in-place pile, a plurality of pile main bars embedded in the cast-in-place pile and having upper ends protruding from the pile head embedded in the reinforced concrete pillar, and a plurality of pile main bars embedded in the reinforced concrete pillar and having upper ends protruding from the pile head embedded in the reinforced concrete pillar when viewed from a vertical direction. stake and a plurality of reinforcing bars arranged surrounding the main bars.

[0008] According to the pile-to-column joint structure of claim 1, a reinforced concrete column is joined to the pile head of the cast-in-place pile. This makes it possible to omit the footing that is usually between the cast-in-place pile and the reinforced concrete column, and eliminates the need for excavation or earth retaining work to build the footing.

[0009] In addition, the upper end of the pile main bar is embedded in the reinforced concrete column, which allows the column to resist the pull-out force even without a footing.

[0010] Furthermore, reinforcement bars are arranged around the main column bars in the reinforced concrete columns, which helps prevent cracks from occurring in the reinforced concrete columns.

[0011] The pile-to-column joint structure of claim 2 is the pile-to-column joint structure of claim 1, wherein the horizontal cross section of the cast-in-place pile is circular and the horizontal cross section of the reinforced concrete column is rectangular, and where the outer diameter of the cast-in-place pile in its horizontal cross section is D and the length of the shortest side of the reinforced concrete column is L, L≧D, and a seismic isolation device is attached to the upper end surface of the reinforced concrete column.

[0012] According to the pile-column joint structure of claim 2, the length L of the shortest side of the rectangular reinforced concrete column is greater than the outer diameter D of the circular cast-in-place pile. Therefore, the cross-sectional area of ​​the reinforced concrete column is greater than the cross-sectional area of ​​the cast-in-place pile. This makes it possible to absorb the construction error of the cast-in-place pile. In addition, by making the cross-sectional area of ​​the column larger, it is easy to attach a seismic isolation device to the upper end surface of the reinforced concrete column, and to form a column head seismic isolation structure.

[0013] The joint structure between a pile and a column of claim 3 is the joint structure between a pile and a column of claim 1 or 2, wherein adjacent reinforced concrete columns are connected by a wall body made of reinforced concrete.

[0014] According to the pile-column joint structure of claim 3, adjacent reinforced concrete columns are connected by a reinforced concrete wall. Therefore, the wall can bear the bending moment acting on the reinforced concrete column. This reduces the bending moment acting on the cast-in-place pile. The joint structure between a pile and a column of claim 4 is the joint structure between a pile and a column of claim 1, in which column main reinforcements are arranged between upper ends of the pile main reinforcements adjacent to each other in the circumferential direction, and the pile main reinforcements and the column main reinforcements form a lap joint. The pile-column joint structure of claim 5 is the pile-column joint structure of claim 1, in which the upper end of the pile main reinforcement and the lower end of the column main reinforcement are connected by a pressure welding or mechanical joint. A joint structure between a pile and a column according to claim 6 is the joint structure between a pile and a column according to claim 2, wherein the cast-in-place pile and the reinforced concrete column are arranged misaligned. Effect of the Invention

[0015] According to the present invention, it is possible to provide a joint structure between a pile and a column that does not require a footing. [Brief description of the drawings]

[0016] [Figure 1] 1 is a plan view showing a building to which a pile-column joint structure according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is an elevational view showing a joint structure between a pile and a column according to an embodiment of the present invention. [Diagram 3] 2. (A) is a cross-sectional view taken along line AA in FIG. 2, (B) is a cross-sectional view taken along line BB in FIG. 2, and (C) is a cross-sectional view taken along line CC in FIG. [Figure 4] (A) is a plan view showing the outer diameter of the pile and the cover depth of the pile, and (B) is a plan view showing the possible installation range of the pillar. [Diagram 5] (A) is a plan view showing a modified example in which walls are arranged along an axis passing through the center of the pillar, (B) is a plan view showing a modified example in which walls are joined to three sides of the pillar, (C) is a plan view showing another modified example in which walls are joined to three sides of the pillar, (D) is a plan view showing a modified example in which walls are joined to four sides of the pillar, and (E) is a plan view showing a modified example in which walls are not joined to the pillar. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a joint structure between a pile and a column according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in each drawing are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and may be present in multiple numbers.

[0018] In addition, the description of the same configuration and reference numerals in each drawing may be omitted. Note that the present invention is not limited to the following embodiment, and may be modified as appropriate within the scope of the object of the present invention, such as omitting configurations or replacing them with different configurations.

[0019] In each figure, the directions indicated by the arrows X and Y are directions along the horizontal plane and are perpendicular to each other. The direction indicated by the arrow Z is a direction along the vertical direction (up and down direction). The directions indicated by the arrows X, Y, and Z in each figure are assumed to be mutually consistent.

[0020] (building) 1 shows an example of a building 12 to which a pile-to-column joint structure 10 (hereinafter referred to as the joint structure 10) according to an embodiment of the present invention is applied. The building 12 includes, at its above-ground portion, reinforced concrete columns 20 and walls 30 connecting adjacent columns 20.

[0021] The wall body 30 is made of reinforced concrete and is disposed so as to be misaligned with the axis CL passing through the center of the column 20. The wall body 30 is a wall beam that also serves as a beam that is spanned between the columns 20, and is thinner and stronger than a typical foundation beam (e.g., 500 mm or more thick). The wall body 30 is thicker (i.e., thicker than 250 mm and less than 500 mm) than a typical wall (e.g., 250 mm or less thick). In this embodiment, the wall body 30 has a height that spans from the lower end to the upper end of the column 20, as shown in FIG. 2.

[0022] (Pile-column joint structure) As shown in FIG. 2, the joint structure 10 is formed including a column 20, reinforcing bars 26, reinforcing bars 28 (see FIG. 3(A)), a wall body 30, a pile 40, pile main bars 42, a seismic isolation device 50, and an upper structure 60.

[0023] (Pile) The pile 40 is a cast-in-place concrete pile directly joined to the column 20. "Directly joined" means that the column 20 and the pile 40 are joined in a state in which the lower end surface of the column 20 and the upper end surface of the pile 40 are in contact with each other and in a state in which stress can be transmitted between the column 20 and the pile 40.

[0024] 3(C), the pile 40 has a circular shape in a plan view (when viewed in a direction along the axial direction of the pile 40, in other words, when viewed in a vertical direction). The outer diameter (diameter) of the pile 40 is defined as D.

[0025] Furthermore, pile main reinforcements 42 are embedded in the pile 40. The pile main reinforcements 42 are a plurality of reinforcing bars embedded inside the pile 40 along the axial direction of the pile 40, and are arranged at predetermined intervals along the circumferential direction of the circle.

[0026] The pile main reinforcements 42 are connected by annular ties 44 arranged to surround the pile main reinforcements 42. The ties 44 are arranged at predetermined intervals in the axial direction of the pile 40.

[0027] The concrete cover thickness of the pile 40 is set to d1. The concrete cover thickness d1 is the thickness of the concrete from the surface (the surface on the outer periphery) of the hoop 44 to the outer periphery of the pile 40.

[0028] As shown in Fig. 2, the upper ends of all the pile main reinforcements 42 protrude from the pile head of the pile 40 and are arranged inside the column 20. Note that the hoops 44, the hoops 24 and the reinforcing bars 28 described below are omitted in Fig. 2. The upper ends of the pile main reinforcements 42 form lap joints with the column main reinforcements 22. The configuration of the lap joints will be described later.

[0029] (Column) As shown in Fig. 2, the column 20 is a column made of reinforced concrete joined to the head of the pile 40. A seismic isolation device 50 is fixed to the upper end surface of the column 20. In addition, an upper structure 60 is fixed to the upper end surface of the seismic isolation device 50. This makes the building 12 a column-head seismic isolation structure.

[0030] As shown in Fig. 3(A), the pillar 20 has a substantially square shape in plan view with the length of each side being L. This length L is greater than the outer diameter D of the pile 40 (see Fig. 3(C)) (L ≥ D).

[0031] The column main reinforcements 22 are embedded in the column 20. The column main reinforcements 22 are a plurality of reinforcing bars embedded inside the column 20 along the axial direction of the column 20, and are arranged at predetermined intervals along the circumferential direction of the circle.

[0032] The column main reinforcements 22 are connected by annular ties 24 arranged to surround the column main reinforcements 22. The ties 24 are arranged at predetermined intervals in the axial direction of the column 20.

[0033] In addition, reinforcing bars 26, 28 are arranged in the column 20 on the outside of the column main reinforcements 22 and the tie bars 24. The reinforcing bars 26 are vertical reinforcements arranged in the axial direction of the column 20 at each of the four corners of the column 20.

[0034] The reinforcing bars 28 are ties arranged to surround the reinforcing bars 26. The reinforcing bars 28 are arranged in the axial direction of the column 20 at predetermined intervals.

[0035] The cover thickness of the pillar 20 is set to be d2. The cover thickness d2 is the thickness of the concrete from the surface of the reinforcing bar 28 to the outer peripheral surface of the pillar 20, and is smaller than the cover thickness d1 of the pile 40.

[0036] (lap joint) As shown in FIG. 2, the length B of the lap joint between the pile main reinforcement 42 and the column main reinforcement 22 (the vertical length from the upper end 42E of the pile main reinforcement 42 to the lower end 22E of the column main reinforcement 22) is appropriately set depending on the diameters and the type of steel of the pile main reinforcement 42 and the column main reinforcement 22, and in this embodiment, as an example, it is set to be 40 times or more the diameter of the pile main reinforcement 42.

[0037] As shown in Fig. 3(B), in the lap joints of the pile main reinforcements 42 and the column main reinforcements 22, the pile main reinforcements 42 and the column main reinforcements 22 are arranged alternately in the circumferential direction. In other words, the column main reinforcements 22 are arranged between the pile main reinforcements 42 adjacent to each other in the circumferential direction.

[0038] In this embodiment, the pile main reinforcement 42 and the column main reinforcement 22 form a lap joint, so that the tensile stress can be transmitted to each other. The length B of this lap joint can be shortened by folding back the upper end of the pile main reinforcement 42 and the lower end of the column main reinforcement 22 to form a hook, or by joining a bearing plate to the upper end of the pile main reinforcement 42 and the lower end of the column main reinforcement 22.

[0039] In addition, by connecting the upper end of the pile main reinforcement 42 and the lower end of the column main reinforcement 22 with pressure welding or a mechanical joint, it is also possible to transmit stress between the pile main reinforcement 42 and the column main reinforcement 22 without using a lap joint.

[0040] (Action and Effects) According to a joint structure 10 according to an embodiment of the present invention, as shown in Fig. 2, a reinforced concrete column 20 is joined to the pile head of a cast-in-place pile 40. This makes it possible to omit the footing that is usually provided between the cast-in-place pile and the reinforced concrete column, and eliminates the need for excavation or earth retaining work to construct the footing.

[0041] In addition, the upper ends of the pile main reinforcements 42 are embedded in the columns 20. This makes it possible to resist the pull-out force applied to the columns 20 even if a footing is omitted.

[0042] 3(A), the column 20 has reinforcing bars 26, 28 arranged around the column main reinforcement 22. This makes it possible to prevent cracks from occurring in the column 20.

[0043] In addition, according to the joint structure 10 of this embodiment, the length L of one side of the rectangular pillar 20 is greater than the outer diameter D of the circular pile 40 (L≧D) as shown in FIG.

[0044] This makes it possible to absorb construction errors in the piles 40. Furthermore, by forming the column 20 with a large cross-sectional area, it becomes easy to attach the seismic isolation device 50 to the upper end surface of the column 20 as shown in Fig. 2, and to form a column-head seismic isolation structure.

[0045] Here, an overview will be given of the absorption margin for construction errors of the pile 40. As shown in Fig. 4(A), the cover thickness of the pile 40 having an outer diameter D is set to a cover thickness d1.

[0046] The pile 40 is formed by pouring concrete into a hole formed by excavating the ground. In general, it is more difficult to control the accuracy of drilling the pile hole and arranging the reinforcing bar cage formed by the pile main reinforcement 42 and the hoop reinforcement 44, compared to erecting steel members on the ground and constructing concrete. For this reason, it is preferable to absorb the construction error of the pile 40 by arranging the column 20 at the design position, as described below.

[0047] FIG. 4(B) shows a state in which the tie bars 24 surrounding the column main reinforcement 22 and the reinforcing bars 28 reinforcing the outer periphery of the column 20 are arranged in contact with each other at contact points PX and PY in the X and Y directions, respectively.

[0048] Since the column main reinforcement bars 22 and tie bars 24 are arranged in the same positions in a plan view as the pile main reinforcement bars 42 and tie bars 44 shown in Figure 4 (A), the planar positions of the column main reinforcement bars 22 and tie bars 24 are determined by the position of the pile 40 and cannot be freely installed.

[0049] On the other hand, the reinforcing bars 28 can be freely installed within the range surrounding the tie bars 24. For example, in the arrangement of the column 20 shown in Fig. 4(B), there is a distance ΔY between the upper part of the reinforcing bars 28 arranged in a rectangular shape and the tie bars 24. Therefore, the reinforcing bars 28 can be installed at any position within the range of ΔY.

[0050] This ΔY is calculated as follows: In the following calculation formula, the diameters of the tie bars 24 and the reinforcing bars 28 are not taken into consideration for the sake of simplicity.

[0051] ΔY = L - 2 × d2 - (D - 2d1) (1)

[0052] Equation (1) can be rearranged to yield equation (2).

[0053] ΔY = L - D + 2 × (d1 - d2) (2) L: Y-direction length of column 20 D: Outer diameter of pile 40 d1: Cover depth at pile 40 d2: Cover thickness at column 20

[0054] In this manner, in this embodiment, the Y-direction length L of the pillar 20 is greater than the outer diameter D of the pile 40, so that a larger installation range for the pillar 20 can be secured compared to a case where the Y-direction length L of the pillar 20 is equal to or less than the outer diameter D of the pile 40.

[0055] In addition, since the cover thickness d1 of the pile 40 in contact with the ground is larger than the cover thickness d2 of the pillar 20, a larger installation range of the pillar 20 can be secured compared to a case where the cover thickness of the pile 40 is equal to or smaller than the cover thickness of the pillar 20. The same applies to the movable range ΔX of the pillar 20 in the X direction.

[0056] In addition, according to the joint structure 10 of this embodiment, as shown in Fig. 1, adjacent columns 20 are connected by a wall body 30 made of reinforced concrete. Therefore, the wall body 30 can bear the bending moment acting on the columns 20. This makes it possible to reduce the bending moment acting on the piles 40.

[0057] In this embodiment, the wall body 30 is disposed so as to be misaligned with the axis CL passing through the center of the pillar 20, but the embodiment of the present invention is not limited to this. For example, as shown in Fig. 5(A), the wall body 30 may be disposed so that the axis CL passing through the center of the pillar 20 becomes the center line.

[0058] In addition, in the present embodiment, the wall body 30 is joined to one end face in the X direction and one end face in the Y direction of the pillar 20 as shown in Fig. 1, but the embodiment of the present invention is not limited to this. For example, as shown in Fig. 5(B), the wall body 30 may be joined to one end face in the X direction and two end faces in the Y direction, or as shown in Fig. 5(C), the wall body 30 may be joined to two end faces in the X direction and one end face in the Y direction.

[0059] Alternatively, as shown in Fig. 5(D), the wall bodies 30 may be joined to the two end faces in the X direction and the two end faces in the Y direction of the pillar 20. Furthermore, as shown in Fig. 5(E), the wall bodies 30 may not be joined to the pillar 20.

[0060] Furthermore, these walls 30 may be of a height such that they are joined from the lower end to the upper end of the pillar 20 as shown in FIG. 1, or may be of a height such that they are joined only to the lower end of the pillar 20.

[0061] In addition, in this embodiment, the pillar 20 is a square with a side length of L in a plan view, but the embodiment of the present invention is not limited to this. For example, the pillar 20 may be a rectangle with each side having a length of L or more (the length of the shortest side is L or more).

[0062] In this embodiment, the length L of one side of the pillar 20 is greater than the outer diameter D of the circular pile 40 (L≧D), but the embodiment of the present invention is not limited to this. For example, the length of one side of the pillar 20 may be greater than or equal to the outer diameter D of the circular pile 40 (L≧D).

[0063] In addition, in this embodiment, the pillar 20 is rectangular, but the embodiment of the present invention is not limited to this. For example, the pillar 20 may be circular. In this case, the length L in the above description should be read as the outer diameter L. [Explanation of symbols]

[0064] 20 Pillars (reinforced concrete pillars) 40 Pile (cast-in-place pile) 42 Pile main reinforcement 26 Reinforcement 28 Reinforcement 30 wall 50 Seismic isolation device

Claims

1. Cast-in-place piles and A reinforced concrete column joined to the pile head of the cast-in-place pile; A plurality of pile main reinforcements are embedded in the cast-in-place piles, and upper ends protruding from the pile head are embedded in the reinforced concrete column; A plurality of reinforcing bars are embedded in the reinforced concrete column and arranged to surround the plurality of pile main reinforcements when viewed in the vertical direction; A joint structure between a pile and a column.

2. The planar cross section of the cast-in-place pile is circular, The horizontal cross section of the reinforced concrete column is rectangular, If the outer diameter of the cast-in-place pile in the horizontal section is D and the length of the shortest side of the reinforced concrete column is L, L ≧ D, A seismic isolation device is attached to the upper end surface of the reinforced concrete column. A pile-to-column joint structure according to claim 1.

3. Adjacent reinforced concrete columns are connected by a reinforced concrete wall. A joint structure between a pile and a column according to claim 1 or 2.

4. A column main reinforcement is disposed between the upper ends of the pile main reinforcements adjacent to each other in the circumferential direction, and the pile main reinforcement and the column main reinforcement form a lap joint. A pile-to-column joint structure according to claim 1.

5. The upper end of the pile main reinforcement and the lower end of the column main reinforcement are connected by a pressure welding or mechanical joint. A pile-to-column joint structure according to claim 1.

6. The cast-in-place pile and the reinforced concrete column are arranged with a misalignment. A joint structure between a pile and a column according to claim 2.

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