Column support structure and method for constructing a column support structure

Abstract

To propose a column support structure that makes it easy to densely fill concrete and improve horizontal resistance performance, and a method for constructing the column support structure.SOLUTION: A column support structure 1 includes a foundation 2, a base plate 41 fixed to the foundation 2 via an anchor bolt 3, and a reinforcing base plate 5 interposed between the foundation 2 and the base plate 41. The reinforcing base plate 5 has an opening 51 formed therein, and also has a bolt insertion hole 52 formed therein in correspondence with a position of the anchor bolt 3. Further, a shear cotter 6 that is embedded in the foundation 2 is formed on a lower surface of the reinforcing base plate 5. Furthermore, the reinforcing base plate 5 is fixed integrally to the base plate 41.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a column support structure and a method for constructing the column support structure.

Background Art

[0002] As a method of erecting a steel column on a reinforced concrete foundation, the base plate of the column base may be fixed to the foundation through anchor bolts. When an external force such as an earthquake acts on such a column support structure, the shear force concentrates on the anchor bolts. Therefore, the anchor bolts need to ensure sufficient shear strength against the shear force. Further, when a large shear force acts on the anchor bolts, the foundation may be pressed by the anchor bolts, and there is a risk of horizontal cone failure. Therefore, Patent Document 1 discloses a structure in which a shear cutter (protruding member) is integrally formed on the base plate and a part of the shear force is borne by the shear cutter embedded in the foundation (foundation concrete), thereby reducing the load on the anchor bolts. Further, Patent Document 2 discloses a column support structure in which a shear cutter (protruding member) is integrally formed on the base plate and the shear cutter is embedded in a mortar layer provided in the middle of the length of the foundation beam. Furthermore, Patent Document 3 discloses a structure in which a part of the shear force is borne by a joining metal object having a shear cutter formed on the lower surface of the pace plate. In Patent Document 3, concrete is placed in a state where a die-cutting die is provided inside a casting die, thereby forming a foundation having a recess opening on the upper surface. With the shear cutter of the joining metal object disposed in the recess, the recess is filled with mortar. The base plate with a shear cutter of Patent Document 1 needs to be installed before placing concrete or mortar, which may interfere with the placing work. In addition, it was necessary to carefully perform the placing work so that poor filling does not occur around the shear cutter. Further, the column support structure of Patent Document 2 is laborious and costly because a space for forming a mortar layer is formed in the middle of the length of the foundation beam. Furthermore, the column support structure described in Patent Document 3 requires the formation of recesses in the base using box-cutting formwork or the like, which is time-consuming and costly. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-173018 [Patent Document 2] Japanese Patent Publication No. 2021-173022 [Patent Document 3] Japanese Patent Publication No. 2021-173023 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention aims to propose a column support structure and a method for constructing this column support structure that facilitates dense concrete filling and improves horizontal resistance performance. [Means for solving the problem]

[0005] The column support structure of the present invention comprises a base, a base plate fixed to the base via anchor bolts, and a reinforcing base plate interposed between the base and the base plate. The reinforcing base plate has openings and bolt insertion holes formed corresponding to the positions of the anchor bolts, and a shear cotter embedded in the base is formed on the lower surface of the reinforcing base plate, and the reinforcing base plate is integrally fixed to the base plate. Furthermore, the method for constructing this column support structure includes an anchor frame installation step of arranging anchor frames, a reinforcing bar assembly step of arranging reinforcing bars, a formwork assembly step of installing formwork, a base formation step of pouring concrete into the formwork to form a base, and a base plate installation step of installing base plates. In the anchor frame installation step, a reinforcing base plate having an opening in the center and a shear cotter embedded in the base is installed on the anchor frame, and anchor bolts protruding from the upper surface of the base are installed. In the base formation step, concrete is poured into the formwork through the opening. Furthermore, in the base plate installation step, the base plate is installed on the reinforcing base plate and fixed integrally with the reinforcing base plate, and the heads of the anchor bolts that pass through the reinforcing base plate and the base plate are fixed to the upper surface of the base plate. According to this column support structure and method for constructing the column support structure, since shear cotters are formed on the reinforcing base plate, the shear force acting on the column base is prevented from concentrating solely on the anchor bolts, and the shear force acting on the column base can be efficiently transmitted to the foundation. Furthermore, since concrete can be poured into the formwork using the openings formed in the reinforcing base plate, concrete can be filled efficiently, and pouring defects around the shear cotter are less likely to occur. Furthermore, the shear cotter includes a cylindrical portion that protrudes downward from the lower surface of the reinforcing base plate so as to surround the opening. ru. Such a shear cotter can be formed by fixing a steel pipe to the lower surface of the reinforcing base plate. [Effects of the Invention]

[0006] According to the column support structure and method for constructing the column support structure of the present invention, it is possible to densely fill the concrete and improve the horizontal resistance performance. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows a column support structure of the first embodiment, where (a) is a plan view and (b) is a cross-sectional view. [Figure 2] This figure shows a reinforcing base plate of the first embodiment, where (a) is a plan view and (b) is a cross-sectional view. [Figure 3] This is a flowchart showing the method for constructing the column support structure of the first embodiment. [Figure 4] This diagram shows an overview of each step in the construction method of the column support structure according to the first embodiment, where (a) is the anchor frame installation step and (b) is the formwork assembly step. [Figure 5] This is a cross-sectional view showing an overview of the foundation formation process of the first embodiment, where (a) shows the concrete pouring process and (b) shows the curing process. [Figure 6] This figure shows the base plate installation process of the first embodiment, where (a) is a plan view and (b) is a cross-sectional view. [Figure 7] This figure shows a column support structure of the second embodiment, where (a) is a plan view and (b) is a cross-sectional view. [Figure 8] This figure shows a reinforcing base plate of the second embodiment, where (a) is a plan view and (b) is a cross-sectional view. [Figure 9] This is a flowchart showing the method for constructing the column support structure of the second embodiment. [Figure 10] This diagram shows an overview of each step in the construction method of the column support structure of the second embodiment, where (a) is the formwork assembly step, (b) is the shear cotter forming step, and (c) is the steel plate placement step. [Figure 11] The following cross-sectional view shows an overview of each step in the construction method of the column support structure, with (a) being the base formation step and (b) being the mortar filling step. [Figure 12] This figure shows the base plate installation process of the second embodiment, where (a) is a plan view and (b) is a cross-sectional view. [Figure 13] This diagram shows a modified column support structure, where (a) is a plan view and (b) is a cross-sectional view. [Modes for carrying out the invention]

[0008] The present invention relates to a column support structure and a construction method thereof, in which, at the joint between the support of the column base portion and the concrete base, concrete can be densely filled under the lower surface of the base plate of the support, and the column support structure has excellent horizontal resistance performance. Fig. 1 shows the column support structure according to an embodiment of the present invention.

[0009] <First Embodiment> As shown in Figs. 1(a) and (b), the column support structure 1 of the first embodiment includes a base 2, an anchor bolt 3 embedded in the base 2, and a support 4 fixed to the base 2 via the anchor bolt 3. A reinforcing base plate 5 is provided between the base 2 and the base plate 41 of the support 4. The base 2 of the present embodiment is made of reinforced concrete and has a prismatic shape with a square cross-section in plan view with a side length of 800 mm. Further, an M42 anchor bolt 3 is embedded in the base 2 of the present embodiment.

[0010] The support 4 is a so-called ball joint, and as shown in Figs. 1(a) and (b), includes a base plate 41, a pedestal 42 erected on the upper surface of the base plate 41, a spherical support globe 43 supported by the pedestal 4, and a plurality of ribs 44, 44,... erected on the upper surface of the base plate 41 around the pedestal 42. The base plate 41 is made of a steel plate with a side length of 640 mm and a thickness of 36 mm. Bolt insertion holes 45 with a size of 120×100 mm are formed in the base plate 41 corresponding to the positions of the anchor bolts 3. The base plate 41 is integrally fixed to the reinforcing base plate 5 by welding W at the periphery. The head of the anchor bolt 3 protrudes from the upper surface of the base 2, passes through a bolt insertion hole 45 formed in the base plate 41, and is fixed to the upper surface of the base plate 41 by a nut 31. In this embodiment, the nut 31 of the anchor bolt 3 is fastened to a washer 33 that covers the bolt insertion hole 45. The washer 33 is made of a steel plate measuring 200 x 190 mm and 22 mm thick, and is fixed to the base plate 41 by welding its perimeter W. In addition, in this embodiment, a double nut is used to prevent loosening.

[0011] Figure 2 shows the reinforcing base plate 5. The reinforcing base plate 5 is made of a steel plate that is square in plan view, with sides of 740 mm and a thickness of 36 mm. As shown in Figure 2, an opening 51 with a diameter of 180 mm is formed in the center, and bolt insertion holes 52 with a diameter of φ47 mm are formed corresponding to the positions of the anchor bolts 3 (see Figure 1). In addition, multiple (four in this embodiment) air vent holes 53 are formed around the opening 51. Furthermore, a shear cotter 6, which will be embedded in the foundation 2, is fixed to the lower surface of this reinforcing base plate 5. The opening 51 has an inner diameter larger than the outer diameter of the concrete pumping pipe used when forming the foundation 2.

[0012] The shear cotter 6 is formed along the periphery of the opening 51 and protrudes downward from the lower surface of the reinforcing base plate 5. The shear cotter 6 is a cylindrical portion with a circular cross-section of φ180 mm and a length of 200 mm, located on the lower surface of the reinforcing base plate 5 so as to surround the opening 51. In this embodiment, the shear cotter 6 is pre-formed integrally with the reinforcing base plate 5 by forging or the like.

[0013] The following describes the method for constructing the column support structure. Figure 3 shows the method for constructing the column support structure. As shown in Figure 3, the method for constructing the column support structure includes an anchor frame installation step S11, a rebar assembly step S12, a formwork assembly step S13, a base formation step S14, and a base plate installation step S15. Figure 4(a) shows the anchor frame installation process S11. As shown in Figure 4(a), the anchor frame installation process S11 is the process of installing the anchor frame 32 that supports the anchor bolts 3 and reinforcing base plate 5 at the position where the base 2 is formed. After the anchor frame 32 is installed, the anchor bolts 3 and reinforcing base plate 5 are installed. When installing the reinforcing base plate 5, the heads of the anchor bolts 3 are inserted through the bolt insertion holes 52. The anchor bolts 3 are made to protrude upward from the upper surface of the reinforcing base plate 5 so as to ensure the length necessary to fix the support 4. A fixing member is formed at the lower end of the anchor bolt 3.

[0014] Reinforcement assembly process S12 is the process of assembling the reinforcement bars (not shown) of the base 2. The reinforcement bars are placed around the anchor bolts 3 (anchor frame 32). The formwork assembly process S13 is the process of assembling the formwork 7 at the location where the base 2 will be formed, as shown in Figure 4(b). The formwork 7 is assembled to surround the anchor bolts 3, anchor frames 32, and reinforcing bars.

[0015] Figure 5(a) shows the base formation process S14. As shown in Figure 5(a), the base formation process S14 is the process of forming the base 2. The base 2 is formed within the formwork 7 with a design standard strength Fc = 30 N / mm 2 The concrete 21 is poured and cured until a predetermined strength is achieved. The shear cotter 6 formed on the lower surface of the reinforcing base plate 5 is inserted into the base 2 (concrete 21) for a predetermined length (200 mm in this embodiment). The concrete 21 is poured into the formwork 7 through the pumping pipe P with the pumping pipe P inserted into the opening 51. The concrete 21 is poured until its upper surface contacts the reinforcing base plate 5, as shown in Figure 5(b).

[0016] The base plate installation process S15 is the process of installing the base plate 41 (bearing 4) on top of the reinforcing base plate 5. Figure 6 shows the base plate installation process S15. As shown in Figures 6(a) and (b), the base plate 41 is integrated with the reinforcing base plate 5 by welding its periphery to the reinforcing base plate 5. In addition, in the base plate installation process S15, a washer 33 through which an anchor bolt 3 that has passed through the reinforcing base plate 5 and the base plate 41 is inserted is installed on the base plate 41, and the periphery of the washer 33 is welded to the base plate 41. Then, a nut 31 is screwed onto the head of the anchor bolt 3, fixing the head of the anchor bolt 3 to the upper surface of the base plate 41 (washer 33).

[0017] According to the column support structure 1 of this embodiment, since shear cotters 6 are formed on the reinforcing base plate 5, the shear force acting on the column base is prevented from concentrating only on the anchor bolts 3, and the shear force acting on the column base can be efficiently transmitted to the foundation 2. Therefore, even when thrust force is generated at the column base, there is no need to increase the specifications (diameter or steel strength) of the anchor bolts 3, and the risk of horizontal cone failure by the anchor bolts 3 can also be reduced. Furthermore, since concrete 21 can be poured into the formwork 7 using the opening 51 formed in the reinforcing base plate 5, the concrete 21 can be filled efficiently, and pouring defects around the shear cotter 6 are less likely to occur. In addition, since the opening in the reinforcing base plate 5 has an inner diameter larger than the outer diameter of the concrete 21 pumping pipe P, concrete 21 can be poured without the need for a funnel or the like, improving work efficiency.

[0018] <Second Embodiment> The column support structure 10 of the second embodiment, as shown in Figures 7(a) and (b), comprises a base 2, anchor bolts 3 embedded in the base 2, and a support 4 fixed to the base 2 via the anchor bolts 3. A reinforcing base plate 5 is interposed between the base 2 and the base plate 41 of the support 4. The base 2 in this embodiment is made of reinforced concrete and has a prism shape with sides of 800 mm, forming a square in plan view. Furthermore, M42 anchor bolts 3 are embedded in the base 2 in this embodiment.

[0019] The support 4 is a so-called ball joint, and as shown in Figures 7(a) and (b), it comprises a base plate 41, a pedestal 42 erected on the upper surface of the base plate 41, a spherical support globe 43 supported by the pedestal 42, and a plurality of ribs 44, 44, ... erected on the upper surface of the base plate 41 around the pedestal 42. The base plate 41 is made of a steel plate with sides of 640 mm and a thickness of 36 mm. The base plate 41 has bolt insertion holes 45 measuring 120 x 100 mm formed in it, corresponding to the positions of the anchor bolts 3. The base plate 41 is integrally fixed to the reinforcing base plate 5 by welding its periphery W. The head of the anchor bolt 3 protrudes from the upper surface of the base 2, passes through a bolt insertion hole 45 formed in the base plate 41, and is fixed to the upper surface of the base plate 41 by a nut 31. In this embodiment, the nut 31 of the anchor bolt 3 is fastened to a washer 33 that covers the bolt insertion hole 45. The washer 33 is made of a steel plate measuring 200 x 190 mm and 22 mm thick, and is fixed to the base plate 41 by welding its perimeter W. In addition, in this embodiment, a double nut is used to prevent loosening.

[0020] Figure 8 shows the reinforcing base plate 5. The reinforcing base plate 5 is made of a steel plate that is square in plan view, with sides of 740 mm and a thickness of 36 mm. As shown in Figure 8, an opening 51 with a diameter of 180 mm is formed in the center, and bolt insertion holes 52 with a diameter of φ47 mm are formed corresponding to the positions of the anchor bolts 3 (see Figure 7). In addition, the reinforcing base plate 5 has multiple air vents 53 formed around the opening 51. Furthermore, a shear cotter 6, which will be embedded in the foundation 2, is fixed to the lower surface of the reinforcing base plate 5. The opening 51 has an inner diameter larger than the outer diameter of the concrete pumping pipe used when forming the foundation 2.

[0021] The shear cotter 6 is formed along the periphery of the opening 51 and protrudes downward from the lower surface of the reinforcing base plate 5. The shear cotter 6 is formed by fixing a steel pipe with a circular cross-section of φ180 mm and a length of 250 mm to the lower surface of the reinforcing base plate 5 so as to surround the opening 51.

[0022] The following describes the method for constructing the column support structure. Figure 9 shows the method for constructing the column support structure. As shown in Figure 9, the method for constructing the column support structure includes a formwork assembly step S21, a shear cotter formation step S22, a steel plate placement step S23, a base formation step S24, a mortar filling step S25, and a base plate installation step S26. Figure 10(a) shows the formwork assembly process S21. As shown in Figure 10(a), the formwork assembly process S21 is the process of assembling the formwork 7 at the position where the base 2 will be formed. In the formwork assembly process S1, as the formwork 7 is assembled, the reinforcing bars (not shown) for the base 2 are placed inside the formwork 7, and anchor bolts 3 are installed. The anchor bolts 3 are made to protrude above the upper end of the formwork 7 in order to secure the length necessary to fix the support 4. A fixing member is formed at the lower end of the anchor bolt 3.

[0023] Figure 10(b) shows the shear cotter forming process S22. The shear cotter forming process S22 is the process of forming the shear cotter 6, as shown in Figure 10(b). The shear cotter 6 is formed by joining (welding) a steel pipe to the lower surface of the reinforcing base plate 5. An opening 51 is formed in advance in the reinforcing base plate 5, and the steel pipe that will become the shear cotter 6 is fixed along the periphery of the opening 51. The inner diameter of the steel pipe is the same as the inner diameter of the opening 51. Note that the order of the formwork installation process S21 and the shear cotter forming process S22 is not limited; the shear cotter forming process S22 may come first or simultaneously. Also, if the shear cotter 6 is already integrally formed with the reinforcing base plate 5, the shear cotter forming process S22 is omitted.

[0024] Figure 10(c) shows the steel plate placement process S23. The steel plate placement process S23 is the process of placing the reinforcing base plate 5, as shown in Figure 10(c). When placing the reinforcing base plate 5, the heads of the anchor bolts 3 are inserted through the bolt insertion holes 52. Although not shown in the figure, the reinforcing base plate 5 is supported by the formwork 7. The support structure of the reinforcing base plate 5 is not limited; for example, it may be placed on the upper end surface of the formwork 7, or it may be fixed to the formwork 7 via a jig or the like. The reinforcing base plate 5 may also be fixed to the anchor bolts 3. In this embodiment, the reinforcing base plate 5 is placed in a position where a predetermined height gap (50 mm in this embodiment) can be secured between the upper surface of the base 2 and the reinforcing base plate 5.

[0025] Figure 11(a) shows the base formation process S24. The base formation process S24 is the process of forming the base 2, as shown in Figure 11(a). The base 2 is formed within the formwork 7 with a design standard strength Fc = 30 N / mm 2 The concrete 21 is poured and cured until a predetermined strength is achieved to form the structure. The shear cotter 6 formed on the lower surface of the reinforcing base plate 5 is inserted into the base 2 (concrete 21) for a predetermined length (200 mm in this embodiment). The concrete 21 is poured (cast) into the formwork 7 through the pumping pipe P with the pumping pipe P inserted into the opening 51.

[0026] Figure 11(b) shows the mortar filling process S25. As shown in Figure 11(b), the mortar filling process S25 is a process of filling the gap between the upper surface of the base 2 and the reinforcing base plate 5 with non-shrink mortar 22. The non-shrink mortar 22 is filled so that no air bubbles remain on the lower surface of the reinforcing base plate 5. The non-shrink mortar 22 has the same design strength (Fc=30N / mm²) as the concrete that makes up the base 2. 2 Use the one from ).

[0027] The base plate installation process S26 is the process of installing the base plate 41 (bearing 4) on top of the reinforcing base plate 5. Figure 12 shows the base plate installation process S26. As shown in Figures 12(a) and (b), the base plate 41 is integrated with the reinforcing base plate 5 by welding its periphery to the reinforcing base plate 5. In addition, in the base plate installation process S26, a washer 33 through which an anchor bolt 3 that has passed through the reinforcing base plate 5 and the base plate 41 is inserted is installed on the base plate 41, and the periphery of the washer 33 is welded to the base plate 41. Then, a nut 31 is screwed onto the head of the anchor bolt 3, fixing the head of the anchor bolt 3 to the upper surface of the base plate 41 (washer 33).

[0028] According to the column support structure 10 of the second embodiment, the same effects and advantages as the column support structure 1 of the first embodiment can be obtained.

[0029] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention. For example, the cross-sectional shape of the steel pipe constituting the shear cotter 6 is not limited to a circle. The steel pipe may be rectangular, for example, as shown in Figures 13(a) and (b). Also, the dimensions of the steel pipe constituting the shear cotter 6 are not limited. Furthermore, the method for forming the shear cotter 6 is not limited to forming it integrally with the reinforcing base plate 5 by forging or fixing a steel pipe to the lower surface of the reinforcing base plate 5. For example, it may be formed from a steel plate or multiple steel rods fixed to the lower surface of the reinforcing base plate 5. Furthermore, the shear cotter 6 does not necessarily have to be a continuous cylindrical body in the circumferential direction; for example, it may be formed intermittently by having slits or the like. Also, the steel pipe constituting the shear cotter 6 may have multiple holes formed in it.

[0030] A mortar other than the non-shrink mortar 22 may be filled between the reinforcing base plate 5 and the foundation 2. Furthermore, the design strength of the concrete 21 and the non-shrink mortar 22 can be determined as appropriate and are not limited to those shown in the above embodiment. The configuration of support 4 is not limited and does not necessarily have to be a ball joint. Furthermore, support 4 can be provided only as needed. The base plate 41 may be directly fixed to the lower end of the member that makes up the column. Furthermore, the dimensions and shapes of the base 2, base plate 41, reinforcing base plate 5, etc., can be determined as appropriate and are not limited to those shown in the above embodiment. [Explanation of Symbols]

[0031] 1 pillar support structure 2. Base 3 Anchor bolts 4 Bearing 41 Base Plate 5. Reinforcement base plate 51 Aperture 52 Bolt insertion holes 6 Sheer Cotter S11 Anchor frame installation process S12 Rebar Assembly Process S13 Formwork Assembly Process S14 Foundation Forming Process S15 Base plate installation process

Claims

1. A column support structure comprising a base, a base plate fixed to the base via anchor bolts, and a reinforcing base plate interposed between the base and the base plate, An opening is formed in the reinforcing base plate, and bolt insertion holes are formed corresponding to the positions of the anchor bolts. A shear cotter is formed on the lower surface of the reinforcing base plate, which is embedded in the base. The reinforcing base plate is fixed integrally with the base plate. The shear cotter is characterized by having a cylindrical portion that protrudes downward from the lower surface of the reinforcing base plate so as to surround the opening, thereby forming a column support structure.

2. The column support structure according to claim 1, characterized in that the shear cotter is a steel pipe fixed to the lower surface of the reinforcing base plate.

3. The anchor frame installation process involves arranging the anchor frame, The rebar assembly process involves placing the reinforcing bars, The formwork assembly process involves installing the formwork, A foundation formation step involves pouring concrete into the formwork to form the base, A method for constructing a column support structure comprising a base plate installation step of installing a base plate, In the anchor frame installation process, a reinforcing base plate having an opening in the center and a shear cotter embedded in the base is installed on the anchor frame, and anchor bolts protruding from the upper surface of the base are arranged. In the aforementioned base formation process, concrete is poured into the formwork through the opening. A method for constructing a column support structure, characterized in that, in the base plate installation step, the base plate is installed on the reinforcing base plate and fixed integrally with the reinforcing base plate, and the heads of the anchor bolts that pass through the reinforcing base plate and the base plate are fixed to the upper surface of the base plate.

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