Precast concrete pillar, construction method for concrete pillar structure, and concrete form device

Abstract

To suppress concrete from flowing out of a hollow part when a precast concrete pillar having the hollow part is stood and the concrete is cast into the hollow part on the site.SOLUTION: A precast concrete pillar 20 comprises a pillar main reinforcement 21 provided on an outer peripheral side, a shearing reinforcement provided surrounding the pillar main reinforcement 21, and an outer shell concrete part 23 formed to embed the pillar reinforcement 21 and shearing reinforcement. The outer shell concrete part 23 has a hollow part 25 formed inside to communicate with the outside on a top surface 23t of the outer shell concrete part 23 and also extend upward and downward, and is formed solidly below the hollow part 25 of the outer shell concrete part 23 to close the lower side of the hollow part 25.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a precast concrete column, a method for constructing a concrete column structure using the precast concrete column, and a formwork device for manufacturing the precast concrete column. [Background technology]

[0002] 2. Description of the Related Art When constructing columns for building structures, it is common to manufacture precast concrete columns having a hollow portion, erect the columns, and pour concrete into the hollow portion on site. For example, Patent Document 1 discloses a hollow precast concrete column that is formed by pouring concrete between an outer form and an inner form. Patent document 2 also discloses a semi-PC column formed from a cylindrical inner formwork, an outer formwork surrounding the inner formwork with a gap on the outside, and concrete poured between the inner formwork and the outer formwork. Moreover, Patent Document 3 discloses a concrete column with a hollow portion formed by pouring concrete into the gap between an outer form and an inner form. In members such as those disclosed in Patent Documents 1 to 3, the hollow portion is provided so as to penetrate the member in the axial direction. Therefore, when these members are used to construct a concrete column, if the member is erected and concrete is poured into the hollow portion from above, the poured concrete may leak out from the opening of the hollow portion provided at the bottom end of the member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-278022 [Patent Document 2] Japanese Patent Application Publication No. 10-140736 [Patent Document 3] Patent No. 6906340 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to suppress the outflow of concrete from a hollow portion when a precast concrete column having a hollow portion is erected and concrete is poured into the hollow portion on-site. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention employs the following means. In other words, the precast concrete column of the present invention comprises column main reinforcements arranged on the outer periphery, shear reinforcement bars arranged to surround the column main reinforcements, and an outer shell concrete part formed to embed the column main reinforcements and the shear reinforcement bars, and is characterized in that a hollow part is formed inside the outer shell concrete part so as to communicate with the outside at the upper surface of the outer shell concrete part and extend in the vertical direction, and below the hollow part of the outer shell concrete part is formed solid, and the lower side of the hollow part is closed. According to the above-mentioned structure, the lower side of the hollow portion of the concrete shell is solid and the lower side of the hollow portion is blocked. Therefore, even if concrete is poured into the hollow portion from above, the poured concrete is prevented from flowing out of the hollow portion by the part that blocks the hollow portion of the concrete shell from below. Therefore, when a precast concrete column having a hollow portion is erected and concrete is poured into the hollow portion on site, it is possible to prevent concrete from flowing out of the hollow portion.

[0006] In one aspect of the present invention, the outer concrete shell has a communication passage extending from the bottom surface of the hollow portion to a side surface of the outer concrete shell, connecting the hollow portion with the outside. According to this configuration, the provision of a communicating passage allows rainwater and impurities that have entered the hollow space during construction to be discharged, thereby suppressing deterioration in the quality of the concrete that is subsequently poured into the hollow space.

[0007] The method for constructing a concrete column structure of the present invention is a method for constructing a concrete column structure using a precast concrete column as described above, and includes a step of installing the precast concrete column on the upper surface of a body, and a step of pouring concrete in place, in which concrete is poured into the hollow portion of the precast concrete column to form a poured-in-place concrete section and integrating the outer shell concrete section with the poured-in-place concrete section. The step of installing the precast concrete column is characterized in that a reinforcing bar protruding upward from the upper surface of the body is connected from below to a reinforcing bar connector which is embedded in the lower end of the outer shell concrete section and has an upper end to which the column main bar of the outer shell concrete section is connected, thereby connecting the column main bar and the reinforcing bar. According to this configuration, a precast concrete column is placed on the top surface of the skeleton, and the reinforcing bars protruding upward from the top surface of the skeleton are connected from below to reinforcing bar connectors embedded in the lower end of the outer concrete shell of the precast concrete column, thereby connecting the main column reinforcement and the reinforcing bars. After that, concrete is poured into the hollow part of the precast concrete column to form the cast-in-place concrete part, and the outer concrete part and the cast-in-place concrete part are integrated to construct the concrete column. At this time, since the bottom of the hollow part of the outer concrete shell is blocked, the outflow of the cast-in-place concrete from the hollow part is prevented. Therefore, the construction of the above-mentioned concrete pillar can be carried out efficiently.

[0008] The formwork device of the present invention is a formwork device for manufacturing a precast concrete column as described above, and comprises an outer formwork which forms the outer shell of the precast concrete column, and an inner formwork which forms the hollow portion of the precast concrete column, the outer formwork being arranged so that the precast concrete column is manufactured with its axial direction being horizontal, the inner formwork being arranged so as to be movable in the axial direction from a portion of the outer formwork which corresponds to the top surface of the precast concrete column, and a plurality of rectangular frame bodies are temporarily fixed with bolts to the surface of the inner formwork, spaced apart in the axial direction, for forming recesses in the wall surface of the hollow portion. According to this configuration, the outer form is provided so that the precast concrete column is manufactured with its axial direction in the horizontal direction. The inner form is provided so as to be movable in the axial direction from a portion of the outer form corresponding to the upper surface of the precast concrete column. The inner form is provided inside the outer form, and concrete is poured between the outer form and the inner form to form the outer shell concrete portion. After the concrete hardens and develops the required strength, the inner form is moved in the axial direction from the portion of the outer form corresponding to the upper surface of the precast concrete column from the inside to the outside of the outer form in such a way that it is pulled out of the hardened concrete, whereby the inner form is removed and the hollow portion of the precast concrete column is formed. Here, a plurality of rectangular frame bodies are temporarily fixed to the surface of the inner formwork with bolts at intervals in the axial direction. Such frame bodies form recesses corresponding to the shape of the frame bodies in the wall surface of the hollow section. As a result, when a concrete column is constructed using a precast concrete column, when concrete is poured into the hollow section to form a cast-in-place concrete section, the poured concrete enters the recesses and hardens. As a result, a cotter that engages with the recesses of the outer shell concrete section is formed in the cast-in-place concrete section, and the outer shell concrete section of the precast concrete column and the cast-in-place concrete section are firmly integrated. In addition, when manufacturing a precast concrete column using a formwork device, concrete is poured between the outer and inner forms, and after the concrete hardens to form the outer concrete shell, the inner formwork is moved in the axial direction to be demolded. If a frame body is provided on the surface of the inner formwork as described above, the frame body will engage with the recess formed in the outer concrete shell, making it difficult to move the inner formwork in the axial direction to pull it out from the hollow part of the outer concrete shell and demold it. Here, according to the above configuration, the frame body is temporarily fixed to the inner formwork with bolts. Therefore, if the temporary fixation by the bolts is released, even if the frame body engages with the recess formed in the outer concrete shell, when the inner formwork is moved in the axial direction to be pulled out from the hollow part of the outer concrete shell, the frame body will be separated from the inner formwork and left in the recess, so that the inner formwork can be easily demolded. Effect of the Invention

[0009] According to the present invention, when a precast concrete column having a hollow portion is erected and concrete is poured into the hollow portion on site, it is possible to prevent concrete from flowing out of the hollow portion. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view showing a concrete column and a concrete column structure constructed using a precast concrete column according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the main column reinforcement and shear reinforcement of a precast concrete column. [Diagram 3] FIG. 3 is a cross-sectional view taken along the line II in FIG. 2. [Figure 4] FIG. 2 is a side view of a precast concrete column. [Diagram 5] This is a cross-sectional view of the outer concrete shell. [Figure 6] A top view of a precast concrete column. [Figure 7] FIG. 3 is a cross-sectional view taken along the line II-II of FIG. 2. [Figure 8]FIG. 2 is a diagram showing a joint between a concrete pillar and a beam. [Figure 9] FIG. 2 is a vertical cross-sectional view showing the configuration of a formwork device. [Figure 10] 10 is a cross-sectional view taken along the line III-III of the formwork device of FIG. 9 in a state in which concrete has been poured into the formwork device to form a precast concrete column. [Figure 11] A cross-sectional view showing a frame body attached to an inner formwork. [Figure 12] This is a diagram showing the state in which the inner formwork is assembled in the manufacturing method of a precast concrete column. [Figure 13] FIG. 2 is a diagram showing the state in which the column main reinforcement and shear reinforcement are arranged in the manufacturing method of a precast concrete column. [Figure 14] FIG. 4 is a cross-sectional view showing a mechanism for removing the inner form. [Figure 15] This figure shows the process of installing a precast concrete column on the top surface of a structure in a method of constructing a concrete column structure. [Figure 16] This figure shows the process of injecting grout material between the bottom end of a precast concrete column and the top surface of the structure in a method for constructing a concrete column structure. [Figure 17] 1 is a diagram showing a state in which a beam is installed on the column capital of a concrete column in a method for constructing a concrete column structure. [Figure 18] FIG. 13 is a diagram showing a concrete pillar structure according to a modified example of an embodiment of the present invention. [Figure 19] FIG. 19 is a diagram showing the concrete pillar shown in FIG. 18 in an exploded state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention relates to a precast concrete column having a hollow portion formed from the top surface of the column to the middle height position of the column and a concrete shell portion formed around the hollow portion, and a concrete column structure in which concrete is poured on-site into the hollow portion constituting the precast concrete column to integrate the concrete shell portion and the poured-in-site concrete. The present invention also relates to a formwork device for manufacturing the precast concrete column, and a method for constructing a concrete column structure using the precast concrete column. Hereinafter, with reference to the attached drawings, a description will be given of an embodiment for carrying out a precast concrete column, a method for constructing a concrete column structure, and a formwork device according to the present invention, based on the drawings. FIG. 1 is a cross-sectional view showing a concrete column and a concrete column structure constructed using a precast concrete column according to an embodiment of the present invention. As shown in FIG. 1, the concrete column structure 1 constitutes a column of the framework of various structures. The concrete column structure 1 is composed of a plurality of concrete columns 2, each having a predetermined length in the vertical direction, connected vertically. Each concrete column 2 is provided on each floor of the structure. A beam 7 is joined to the column capital 2a of the concrete column 2 on each floor. The concrete column 2 on the lowest floor is provided on a foundation 4. The concrete columns 2 provided on floors above the lowest floor are connected to the concrete column 2 on the floor directly below. The concrete pillar 2 comprises a precast concrete pillar 20 and a cast-in-place concrete section 30.

[0012] Fig. 2 is a diagram showing the column main reinforcement and shear reinforcement of a precast concrete column. Fig. 3 is a cross-sectional view taken along the line II in Fig. 2. 1 to 3, a precast concrete column 20 includes a column main reinforcement 21, a shear reinforcement 22, and an outer shell concrete portion 23. In this embodiment, the precast concrete column 20 is formed in a tubular shape with a rectangular cross section when viewed from above. The column main reinforcements 21 are provided on the outer periphery of the precast concrete column 20. As shown in Fig. 3, the column main reinforcements 21 are provided in a plurality of rows near each of the four corners 20c when viewed from above. Each column main reinforcement 21 extends in the vertical direction. As shown in Figs. 1 and 2, the column main reinforcements 21 are provided protruding upward from the upper surface 23t of the outer shell concrete portion 23. The shear reinforcement bars 22 are provided so as to surround the multiple column main reinforcements 21. The multiple shear reinforcement bars 22 are provided at intervals in the vertical direction.

[0013] Fig. 4 is a side view of a precast concrete column. Fig. 5 is a cross-sectional view of the outer concrete shell. For simplicity, the column main reinforcement 21 and the shear reinforcement 22 are not drawn in Fig. 5. Fig. 6 is a view of the precast concrete column seen from above. The outer concrete shell portion 23 is made of concrete. As shown in Fig. 1 and Fig. 4 to Fig. 6, the outer concrete shell portion 23 integrally includes a cylindrical portion 23s and a closing portion 23z. The cylindrical portion 23s extends in the up-down direction. The column main reinforcement bars 21 and the shear reinforcement bars 22 are embedded in the cylindrical portion 23s. In other words, the outer shell concrete portion 23 is formed so that the column main reinforcement bars 21 and the shear reinforcement bars 22 are embedded therein. The blocking portion 23z blocks the inside of the cylindrical portion 23s at the lower end of the cylindrical portion 23s. The blocking portion 23z makes the lower end of the outer shell concrete portion 23 solid. The blocking portion 23z is formed so that the portion below the middle portion in the vertical direction of the precast concrete column 20 is solid. In this embodiment, in particular, the blocking portion 23z is formed so that the lower end portion of the precast concrete column 20 is solid.

[0014] A hollow section 25 extending in the vertical direction is formed inside the cylindrical section 23s of the concrete shell 23. As shown in FIG. 6, the hollow section 25 is formed so that its shape when viewed from above is approximately rectangular. The hollow section 25 is defined by the four inner side surfaces of the concrete shell 23, which serve as wall surfaces 23f. The hollow section 25 opens upward at the upper surface 23t of the concrete shell 23 and communicates with the outside. The lower side of the hollow section 25 is closed by a closing section 23z. The hollow section 25 is formed so that the cross-sectional area perpendicular to the axial direction (vertical direction) gradually decreases from the upper surface 23t of the concrete shell 23 downward. Chamfered sections 25m are formed at the four corners of the hollow section 25 so that the rectangular corners are rounded. 5, a plurality of recesses 28 are formed at intervals in the axial direction of the concrete shell 23 on the four wall surfaces 23f of the concrete shell 23 that form the hollow portion 25. Each recess 28 is formed, for example, in a rectangular shape when viewed from a direction perpendicular to each wall surface 23f.

[0015] 6, a plurality of support plates 26 are provided on the upper surface 23t of the outer shell concrete portion 23. Each support plate 26 is made of metal, and is used when removing the inner formwork 120 (described later) during the manufacture of the precast concrete column 20. As shown in Figures 4 and 5, a communication passage 27 is formed in the outer concrete part 23. The communication passage 27 is formed so as to extend downward from the bottom surface 23u of the hollow part 25, i.e., the upper surface 23u of the closing part 23z, and then bends laterally to one side surface 23d of the outer concrete part 23. The communication passage 27 connects the hollow part 25 to the outside of the outer concrete part 23. The communication passage 27 is formed, for example, by burying a bent sheath tube 27P in the concrete that forms the closing part 23z.

[0016] As shown in Figs. 1 and 2, a plurality of reinforcing bar connectors 29 are embedded in the lower end of the outer shell concrete portion 23. The reinforcing bar connectors 29 are so-called mechanical connectors, and the lower ends of the column main reinforcements 21 are connected to the upper ends of the reinforcing bar connectors 29. Some of the reinforcing bar connectors 29A among the plurality of reinforcing bar connectors 29 are disposed above the other reinforcing bar connectors 29 by providing a height-raising jig 29k on the lower side. The height-raising jig 29k is provided with a communication hole (not shown) in the vertical direction. The lower end of the height-raising jig 29k is provided so as to be exposed on the lower surface 23g of the outer shell concrete portion 23. The lower ends of the other reinforcing bar connectors 29 other than some of the reinforcing bar connectors 29A are provided so as to be exposed on the lower surface 23g of the outer shell concrete portion 23.

[0017] 1, reinforcing bars S protruding upward from the top surface of the skeleton 3 are connected from below to each reinforcing bar connector 29. Here, the reinforcing bars protruding upward from the top surface of the skeleton 3 refer to reinforcing bars 5 protruding upward from the top surface of the foundation 4 in the case of a concrete column 2 placed on the lowest floor, and refer to main column bars 21 protruding upward from another concrete column 2 placed on the floor immediately below in the case of a concrete column 2 placed on a floor higher than the lowest floor. Among the reinforcing bars S protruding upward from the upper surface of the skeleton 3, some of the reinforcing bars SA have a larger upward protruding dimension than the other reinforcing bars S. These reinforcing bars SA are provided corresponding to the reinforcing bar connectors 29A arranged above, and are inserted into the reinforcing bar connectors 29A arranged above by being inserted through the communication holes of the height-raising jig 29k. When the precast concrete column 20 is installed, when the multiple reinforcing bars S protruding upward from the upper surface of the skeleton 3 are inserted into the multiple reinforcing bar connectors 29 of the precast concrete column 20, the reinforcing bars SA having a larger upward protruding dimension are inserted into the inside of the precast concrete column 20 from the lower surface 23g of the precast concrete column 20 before the other reinforcing bars S. This makes it possible to easily position the precast concrete column 20 relative to the skeleton 3, and the other reinforcing bars S can be easily and reliably inserted into the other reinforcing bar connectors 29.

[0018] FIG. 7 is a cross-sectional view taken along line II-II of FIG. 2, 4, and 7, the outer concrete portion 23 is formed with grout injection holes 31 and grout discharge holes 32 that communicate from the side surface of the outer concrete portion 23 to the inside of each reinforcing bar joint 29. The grout injection holes 31 are formed to communicate with the lower part of the reinforcing bar joint 29. The grout discharge holes 32 are formed to communicate with the upper part of the reinforcing bar joint 29.

[0019] When constructing a concrete column 2 using a precast concrete column 20 as a member, concrete is poured into the hollow portion 25 to fill it, forming a cast-in-place concrete portion 30 as shown in FIG. 1. The cast-in-place concrete portion 30 is formed to the same height as the upper end of a blocking plate 8 provided on the precast concrete column 20, which will be described next. In the hollow portion 25, the concrete of the cast-in-place concrete portion 30 fills a plurality of recesses 28 shown in FIG. 5. When the concrete that has filled each recess 28 hardens, a protrusion is formed in the cast-in-place concrete portion 30 that protrudes toward the outer shell concrete portion 23 located outside the cast-in-place concrete portion 30. This protrusion functions as a cotter that engages with the outer shell concrete portion 23, and the cast-in-place concrete portion 30 and the outer shell concrete portion 23 are firmly joined together.

[0020] FIG. 8 is a diagram showing a joint between a concrete pillar and a beam. 1 and 8, a beam 7 that supports the floor of each floor from below is joined to the column capital 2a of the concrete column 2. In this embodiment, the beam 7 is a steel beam. An angle plate 71, for example made of an L-shaped steel, is joined to the column main reinforcement 21 protruding upward from the upper surface 23t of the outer shell concrete portion 23 so as to extend in the horizontal direction. The beam 7 is provided so as to be supported on this angle plate 71. The gap between adjacent beams 7 is closed by a closing plate 8. The closing plate 8 is provided so as to surround the joint between the concrete column 2 and the beam 7 from the side. The closing plate 8 is provided so that its lower end is located on the outer peripheral surface of the outer shell concrete portion 23. As already explained, when concrete is poured into the hollow portion 25 to form the cast-in-place concrete portion 30, the concrete is poured up to the inside of the closing plate 8 located above the hollow portion 25. In this way, the cast-in-place concrete portion 30 is formed integrally between the inside of the hollow portion 25 and the inside of the closing plate 8. The portion of the beam 7 located inside the closing plate 8 and the angle plate 71 are embedded in the cast-in-place concrete portion 30.

[0021] (Formwork Equipment) Fig. 9 is a vertical cross-sectional view showing the configuration of the formwork device, Fig. 10 is a cross-sectional view taken along line III-III of Fig. 9 showing a state in which concrete has been poured into the formwork device to form a precast concrete column. As shown in Figures 9 and 10, the formwork device 100 for forming the precast concrete column 20 includes an outer formwork 110 and an inner formwork 120. The outer formwork 110 forms the outer shell of the precast concrete column 20. The outer formwork 110 is provided so that the precast concrete column 20 is manufactured with its axis direction aligned horizontally. The outer formwork 110 includes a lower frame plate 111, a pair of side frame plates 112, a first end plate 113, and a second end plate 114.

[0022] The lower frame plate 111 is placed on a base (bed surface) 101 provided on the floor surface of a factory, work yard, etc. in which the formwork device 100 is installed. The lower frame plate 111 is formed in a rectangular shape when viewed from above. The lower frame plate 111 forms one of the side surfaces of the outer concrete shell portion 23. More specifically, the lower frame plate 111 forms the side surface 23e of the outer concrete shell portion 23 opposite the side surface 23d in which the communication passage 27 is formed. The pair of side frame plates 112 rise upward from both widthwise sides of the lower frame plate 111. The pair of side frame plates 112 form two side surfaces adjacent to both sides of the side surface 23e of the outer concrete shell portion 23 formed by the lower frame plate 111.

[0023] As shown in Figure 9, the first end plate 113 closes the space between the lower frame plate 111 and a pair of side frame plates 112 on one axial side of the precast concrete column 20 to be formed (the left side of the paper in Figure 9). The first end plate 113 is provided along a plane perpendicular to the axial direction of the precast concrete column 20 to be formed. The first end plate 113 forms the lower surface 23g of the outer shell concrete portion 23. The lower frame plate 111, the pair of side frame plates 112, and the first end plate 113 of the outer formwork 110 are each made of metal, for example, and are detachably connected by bolts, nuts, etc. (not shown). The second end plate 114 is provided between the lower frame plate 111 and the pair of side frame plates 112 on the other axial side of the precast concrete column 20 to be formed (the right side of the paper in Figure 9). The second end plate 114 is provided along a plane perpendicular to the axial direction of the precast concrete column 20 to be formed. An opening 115 (see Figure 9) through which the inner formwork 120 can be inserted is formed in the center of the second end plate 114. The second end plate 114 forms the upper surface 23t of the outer shell concrete portion 23.

[0024] The inner formwork 120 integrally comprises a cylindrical portion 121 extending along the axial direction of the precast concrete column 20 to be formed, and an end plate 122. The cylindrical portion 121 is formed to have a rectangular shape when viewed from the axial direction. Each surface of the cylindrical portion 121 is formed to have a trapezoid shape such that the width, i.e., the length in the direction perpendicular to the axial direction, gradually decreases from the other side to one side in the axial direction. Such a cylindrical portion 121 forms the inner peripheral surface of the outer shell concrete portion 23, i.e., the wall surface 23f of the hollow portion 25. The cylindrical portion 121 is provided on the other side in the axial direction inside the opening 115 of the second end plate 114, and is detachably joined to the second end plate 114 by bolts and nuts.

[0025] The end plate 122 closes one end of the axial direction of the cylindrical portion 121, i.e., the tip portion where the width of each face of the cylindrical portion 121 is smallest. The end plate 122 forms the upper surface 23u of the closing portion 23z of the outer shell concrete portion 23, i.e., the bottom surface 23u of the hollow portion 25. The cylindrical portion 121 and the end plate 122 are made of, for example, metal plates, and are welded together to form the inner formwork 120. The tip end side of the inner formwork 120, on which the end plate 122 is provided, is supported by a support metal fitting 128 provided on the lower frame plate 111. As will be described later, when concrete is poured into the formwork device 100 and the precast concrete column 20 is manufactured, the support metal fitting 128 is left embedded in the concrete. For this reason, for example, a fixed auxiliary material that is normally used to ensure the cover for the reinforcing bar position may be used as the support metal fitting 128.

[0026] As described above, the cylindrical portion 121 is detachably joined to the second end plate 114 by bolts and nuts. Therefore, by releasing the joining between the cylindrical portion 121 and the second end plate 114, sliding the second end plate 114 in the axial direction relative to the cylindrical portion 121, and then joining the cylindrical portion 121 and the second end plate 114 again by bolts and nuts, it is possible to adjust the axial distance H between the second end plate 114 and the end plate 122. This makes it possible to adjust the height (depth) of the hollow portion 25 of the precast concrete column 20 to be manufactured.

[0027] As shown in FIG. 9, a plurality of rectangular frame bodies 130 are provided on each side of the inner mold 120. FIG. 11 is a cross-sectional view showing a frame body attached to the inner formwork. The frame 130 includes a flat plate portion 130a having a rectangular shape in a plan view, and side plate portions 130b joined to the four end sides of the flat plate portion 130a. In this manner, the frame 130 is formed in a box-like shape without a lid. A plurality of frame bodies 130 are provided at intervals in the axial direction on each surface of the cylindrical portion 121. The frame body 130 is provided so that the end side of the side plate portion 130b opposite to the flat plate portion 130a abuts against the surface of the cylindrical portion 121. In the frame body 130, a nut 132 is welded to the side of the flat plate portion 130a facing the cylindrical portion 121. The frame body 130 is temporarily fixed to the inner formwork 120 in a detachable manner by screwing the tip end of a bolt 135 inserted into a female screw hole formed through the cylindrical portion 121 into the nut 132. In this way, the frame body 130 is provided so as to protrude from the surface of the cylindrical portion 121. The frame body 130 forms a recess 28 in the wall surface 23f of the hollow portion 25 when the precast concrete column 20 is manufactured.

[0028] (Manufacturing method of precast concrete columns) FIG. 12 is a diagram showing the inner formwork assembled in the manufacturing method for a precast concrete column. To form a precast concrete column 20 using such a formwork device 100, first, as shown in FIG. 12, the lower frame plate 111 is set on the base 101. Next, the inner form 120 is assembled on the lower frame plate 111, or the inner form 120 assembled at a different location is placed on the lower frame plate 111. The second end plate 114 is assembled integrally with the inner form 120. The second end plate 114 side of the inner form 120 in the axial direction is supported by grounding the second end plate 114 on the lower frame plate 111. The end plate 122 side of the inner form 120 in the axial direction is supported via a support metal fitting 128. In this way, the inner form 120 is fixed in a state where it is spaced upward from the lower frame plate 111.

[0029] FIG. 13 is a diagram showing the state in which column main reinforcement bars and shear reinforcement bars are arranged in a manufacturing method for a precast concrete column. Thereafter, as shown in Fig. 13, the column main reinforcement bars 21 and the shear reinforcement bars 22 are arranged around the inner formwork 120. The column main reinforcement bars 21 are inserted into through holes (not shown) formed in advance in the second end plate 114, and protrude to the other side in the axial direction. A reinforcing bar connector 29 is connected to one end of the column main reinforcement bars 21 in the axial direction. In addition, a support plate 26 is set in a prescribed position on the second end plate 114, as shown in Figs. 6 and 10. Furthermore, a sheath tube 27P for forming the communication passage 27 is set. The sheath tube 27P is provided so that one end thereof abuts against or penetrates the end plate 122 of the inner formwork 120. The other end of the sheath tube 27P is provided so as to open upward at a position opposite the second end plate 114 with respect to the end plate 122. In this way, by providing the sheath tube 27P so that the other end opens upward, it is possible to prevent concrete from entering the inside of the sheath tube 27P when pouring the concrete, as will be described later. Next, a pair of side frame plates 112 and a first end plate 113 are joined to the lower frame plate 111 and set in place to assemble the outer formwork 110.

[0030] Thereafter, concrete is poured from above so as to embed the inner form 120 inside the outer form 110 surrounded by the pair of side frame plates 112, the first end plate 113, and the second end plate 114. The concrete is poured up to the level of the upper ends of the pair of side frame plates 112, and the surface is smoothed. The poured concrete then hardens and develops a predetermined strength, forming the outer concrete shell portion 23.

[0031] FIG. 14 is a cross-sectional view showing a mechanism for removing the inner form. Thereafter, the form device 100 is removed. To do this, first, a worker enters the cylindrical portion 121 of the inner form 120 and loosens the bolts 135 shown in Fig. 11 to release the connections between the cylindrical portion 121 and each frame body 130. 14, the pressing bolts 92 are screwed into the nuts 91 welded to the second end plate 114 at positions corresponding to the receiving plates 26, and their tips are pressed against the receiving plates 26 through the second end plate 114. In this state, the pressing bolts 92 are rotated in a direction in which the tips of the pressing bolts 92 press against the receiving plates 26. Then, the second end plate 114 tries to move away from the upper surface 23t of the outer concrete part 23, which is further pressed by the receiving plates 26. Accordingly, the entire inner formwork 120 fixed to the second end plate 114 is pulled out from the hollow part 25 formed in the outer concrete part 23 to the other side in the axial direction.

[0032] Here, since each frame body 130 is disconnected from the cylindrical portion 121, after the inner formwork 120 is pulled out, each frame body 130 is left inside the recess 28 formed corresponding to the frame body 130. After the inner formwork 120 has been completely pulled out from the hollow portion 25 formed in the outer concrete portion 23, a worker may enter the hollow portion 25 and remove each of the frame bodies 130 from the recesses 28 of the hollow portion 25. Also, each of the frame bodies 130 may be left in the recesses 28 as they are. Thereafter, the pair of side frame plates 112 and the first end plate 113 constituting the outer formwork 110 are dismantled and removed. In this manner, the precast concrete column 20 is manufactured.

[0033] (How to build a concrete column structure) Next, a method for constructing the concrete column structure 1 using the precast concrete column 20 as described above will be described. FIG. 15 is a diagram showing a process of installing a precast concrete column on the top surface of a framework in a method for constructing a concrete column structure. As shown in Fig. 15, the precast concrete column 20 manufactured as described above is installed on the upper surface of the skeleton 3. When the precast concrete column 20 is installed on the lowest floor, the skeleton 3 is the foundation 4. When the precast concrete column 20 is placed on a floor higher than the lowest floor, the skeleton 3 is another concrete column 2 that has already been constructed on the floor immediately below.

[0034] When installing the precast concrete column 20 on the top surface of the skeleton 3, the reinforcing bars S protruding upward from the top surface of the skeleton 3 are connected from below to reinforcing bar connectors 29 embedded in the lower end of the outer concrete shell 23. This connects the column main reinforcement bars 21 and the reinforcing bars S. Here, in the case of a concrete column 2 placed on the lowest floor, the reinforcing bars S are the reinforcing bars 5 protruding upward from the top surface of the foundation part 4, and in the case of a concrete column 2 placed on a floor higher than the lowest floor, the reinforcing bars S are the column main reinforcement bars 21 protruding upward from another concrete column 2 constructed on the floor immediately below. Here, when the reinforcing bars S protruding upward from the top surface of the skeleton 3 are connected to the reinforcing bar connectors 29 from below, some reinforcing bars SA with larger upward protruding dimensions are inserted from the bottom surface 23g of the precast concrete column 20 into the interior of the precast concrete column 20 prior to the other reinforcing bars S. This allows the other reinforcing bars S to be inserted easily and reliably into the other reinforcing bar connectors 29.

[0035] FIG. 16 is a diagram showing a process of injecting grout material between the bottom end of a precast concrete column and the top surface of a concrete structure in a method for constructing a concrete column structure. As shown in FIG. 16, after all the reinforcing bars S are connected to the reinforcing bar joints 29, high-strength grout material G is injected from the grout injection holes 31 (see FIG. 2 and FIG. 4). The grout material G injected from the grout injection holes 31 flows downward from the grout injection holes 31 into the joints between the lower surface 23g of the outer shell concrete part 23 of the precast concrete column 20 and the upper surface of the skeleton 3, while flowing upward from the reinforcing bar joints 29 into which the grout material G has been injected, and is filled inside the reinforcing bar joints 29. Then, the grout material G is discharged from the grout discharge holes 32 located above the grout injection holes 31 of the reinforcing bar joints 29 into which the grout material G has been injected, and the grout discharge holes 32 are plugged. Thereafter, the grout material G is circulated and filled into the other reinforcing bar joints 29 through the joints. After the precast concrete column 20 is installed on the top surface of the main body 3, and before concrete is poured on-site into the hollow section 25 as described below, rainwater, impurities, etc. that have entered the hollow section 25 are discharged through the connecting passage 27 (see Figures 4 and 5) from the bottom of the hollow section 25 to the outside of the outer shell concrete section 23.

[0036] FIG. 17 is a diagram showing a state in which a beam is installed on the column capital of a concrete column in a method for constructing a concrete column structure. After that, an angle plate 71 is joined to the column main reinforcement 21 protruding upward from the upper surface 23t of the outer shell concrete part 23 at the column head of the precast concrete column 20. Then, as shown in Fig. 17, a beam 7 is placed on the angle plate 71, and a closing plate 8 is installed. Next, as shown in Fig. 1, concrete is poured inside the closing plate 8. The concrete poured inside the closing plate 8 is poured in situ into the hollow portion 25 and inside the closing plate 8 from above the precast concrete column 20. As a result, a cast-in-situ concrete portion 30 is formed inside the hollow portion 25 and inside the closing plate 8. The concrete poured in situ inside the hollow portion 25 hardens and develops the required strength, thereby integrating the outer shell concrete portion 23 with the cast-in-situ concrete. In this way, the concrete pillars 2 for one story are constructed. After this, the concrete pillars 2 for each story are constructed in sequence using the same procedure as above.

[0037] The precast concrete column 20 as described above comprises column main reinforcements 21 provided on the outer periphery, shear reinforcement bars 22 provided to surround the column main reinforcements 21, and an outer shell concrete portion 23 formed to embed the column main reinforcements 21 and the shear reinforcement bars 22. Inside the outer shell concrete portion 23, a hollow portion 25 is formed which communicates with the outside at the upper surface 23t of the outer shell concrete portion 23 and extends in the vertical direction. Below the hollow portion 25 of the outer shell concrete portion 23, the outer shell concrete portion 23 is formed solid, and the lower side of the hollow portion 25 is blocked. According to the above-mentioned configuration, the lower side of hollow portion 25 of outer shell concrete portion 23 is formed solid, and the lower side of hollow portion 25 is blocked. Therefore, even if concrete is poured into hollow portion 25 from above, the poured concrete is prevented from flowing out of hollow portion 25 by the part that blocks hollow portion 25 of outer shell concrete portion 23 from below. Therefore, when a precast concrete column 20 having a hollow portion 25 is erected and concrete is poured into the hollow portion 25 on site, the outflow of concrete from the hollow portion 25 can be suppressed.

[0038] Further, in the outer concrete portion 23, a communication passage 27 is formed which extends from the bottom surface 23u of the hollow portion 25 to the side surface 23d of the outer concrete portion 23 and connects the hollow portion 25 with the outside. According to this configuration, by providing the communicating passage 27, rainwater and impurities that have entered the hollow portion 25 during construction can be discharged, thereby suppressing deterioration in the quality of the concrete that is subsequently poured into the hollow portion 25 on-site.

[0039] In addition, the hollow portion 25 is formed so that its cross-sectional area gradually decreases downward from the upper surface 23t of the outer shell concrete portion 23, and a plurality of recesses 28 are provided in the wall surface 23f of the hollow portion 25 at intervals in the axial direction of the outer shell concrete portion 23. According to this configuration, the hollow section 25 is formed so that its cross-sectional area gradually decreases from the top surface 23t of the outer concrete section 23 downward, and therefore the inner formwork 120 forming the hollow section 25, which is used when manufacturing the precast concrete column 20, has a corresponding shape that gradually becomes narrower from the top surface 23t toward the tip. Therefore, when manufacturing the precast concrete column 20 using the formwork device 100, it is easy to pull out the inner formwork 120 from the top surface 23t side of the outer concrete section 23. Furthermore, a plurality of recesses 28 are provided on the wall surface 23f of the hollow portion 25 at intervals in the axial direction of the outer shell concrete portion 23. Therefore, when constructing the concrete pillar 2 using the precast concrete column 20, when concrete is poured into the hollow portion 25 to form the cast-in-place concrete portion 30, the poured concrete fills the recesses 28 and hardens. As a result, a cotter is formed in the cast-in-place concrete portion 30, and the outer shell concrete portion 23 of the precast concrete column 20 and the cast-in-place concrete portion 30 are firmly integrated.

[0040] Furthermore, the method for constructing the concrete column structure 1 as described above is a method for constructing the concrete column structure 1 using the precast concrete column 20 as described above, and includes a step of installing the precast concrete column 20 on the upper surface of the main body 3, and a step of pouring concrete in situ in the hollow portion 25 of the precast concrete column 20 to form the cast-in-situ concrete portion 30 and integrating the cast-in-situ concrete with the outer shell concrete portion 23. In the step of installing the precast concrete column 20, the reinforcing bar S protruding upward from the upper surface of the main body 3 is connected from below to a reinforcing bar connector 29 which is embedded in the lower end of the outer shell concrete portion 23 and has the column main bar 21 of the outer shell concrete portion 23 connected to its upper end, thereby connecting the column main bar 21 and the reinforcing bar S. According to this configuration, the precast concrete column 20 is placed on the top surface of the skeleton 3, and the reinforcing bars S protruding upward from the top surface of the skeleton 3 are connected from below to reinforcing bar joints 29 embedded in the lower end of the outer shell concrete portion 23 of the precast concrete column 20, thereby connecting the column main reinforcement 21 and the reinforcing bars S. Thereafter, concrete is poured into the hollow portion 25 of the precast concrete column 20 on site to form the cast-in-place concrete portion 30, thereby integrating the outer shell concrete portion 23 and the cast-in-place concrete portion 30, and the concrete column 2 is constructed. At this time, since the lower side of the hollow portion 25 of the outer concrete shell portion 23 is closed, the outflow of the cast-in-place concrete from the hollow portion 25 is prevented. Therefore, the construction of the concrete pillar 2 as described above can be carried out efficiently.

[0041] Furthermore, the formwork device 100 of the present invention is a formwork device 100 for manufacturing a precast concrete column 20 as described above, and comprises an outer formwork 110 which forms the outer shell of the precast concrete column 20, and an inner formwork 120 which forms the hollow portion 25 of the precast concrete column 20, the outer formwork 110 is provided so that the precast concrete column 20 is manufactured with its axial direction being horizontal, the inner formwork 120 is provided so as to be movable in the axial direction from a portion of the outer formwork 110 which corresponds to the upper surface 23t of the precast concrete column 20, and a plurality of rectangular frame bodies 130 are temporarily fixed to the surface of the inner formwork 120 with bolts 135, spaced apart in the axial direction, for forming recesses 28 in the wall surface 23f of the hollow portion 25. According to this configuration, the outer form 110 is provided so that the precast concrete column 20 is manufactured with its axial direction in the horizontal direction. The inner form 120 is provided so as to be movable in the axial direction from a portion of the outer form 110 corresponding to the upper surface 23t of the precast concrete column 20. The inner form 120 is provided inside the outer form 110, and concrete is poured between the outer form 110 and the inner form 120 to form the outer shell concrete portion 23. After the concrete hardens and develops a required strength, the inner form 120 is moved in the axial direction from the portion of the outer form 110 corresponding to the upper surface 23t of the precast concrete column 20 from the inside to the outside of the outer form 110 as if it were pulled out of the hardened concrete, whereby the inner form 120 is removed from the form, and the hollow portion 25 of the precast concrete column 20 is formed. Here, a plurality of rectangular frame bodies 130 are temporarily fixed to the surface of the inner formwork 120 with bolts 135 at intervals in the axial direction. Such frame bodies 130 form recesses 28 corresponding to the shape of the frame bodies 130 on the wall surface 23f of the hollow portion 25. As a result, when constructing the concrete column 2 using the precast concrete column 20, when concrete is poured into the hollow portion 25 to form the cast-in-place concrete portion 30, the poured concrete enters the recesses 28 and hardens. As a result, a cotter that engages with the recesses 28 of the outer shell concrete portion 23 is formed in the cast-in-place concrete portion 30, and the outer shell concrete portion 23 of the precast concrete column 20 and the cast-in-place concrete portion 30 are firmly integrated. In addition, when manufacturing a precast concrete column 20 using the formwork device 100, concrete is poured between the outer formwork 110 and the inner formwork 120, and after the concrete hardens to form the outer concrete shell 23, the inner formwork 120 is moved in the axial direction to be removed. If the frame body 130 is provided on the surface of the inner formwork 120 as described above, the recess 28 formed in the outer concrete shell 23 and the frame body 130 will engage, making it difficult to remove the inner formwork 120 by moving it in the axial direction so as to pull it out of the hollow portion 25 of the outer concrete shell 23. Here, according to the above configuration, the frame body 130 is temporarily fixed to the inner formwork 120 by the bolts 135. Therefore, if the temporary fixation by bolt 135 is released, even if the recess 28 formed in the outer shell concrete portion 23 engages with the frame body 130, when the inner formwork 120 is moved axially so as to be pulled out from the hollow portion 25 of the outer shell concrete portion 23, the frame body 130 will separate from the inner formwork 120 and be left in the recess 28, so that the inner formwork 120 can be easily removed.

[0042] (Modification of the embodiment) The precast concrete columns, the method for constructing a concrete column structure, and the formwork device of the present invention are not limited to the above-mentioned embodiments described with reference to the drawings, and various modifications are possible within the technical scope. For example, in the above embodiment, the columns on each floor are described as being formed from the same precast concrete columns 20, but this is not limited to the above. Fig. 18 is a diagram showing a concrete pillar structure according to a modified example of the embodiment of the present invention, and Fig. 19 is a diagram showing the concrete pillar shown in Fig. 18 in an exploded state. For example, as shown in Fig. 17 and Fig. 18, the concrete column 2 on the lowest floor may be formed by a precast concrete column 20 having an outer shell concrete part 23 with a closing part 23z at the lower end as described above, and a precast concrete column on an upper floor placed on the precast concrete column 20 may be formed by an upper precast concrete column 20J having a structure different from that of the precast concrete column 20. The upper precast concrete column 20J does not have a closing part 23z like the precast concrete column 20 on the lowest floor. In other words, the outer shell concrete part 23J of the upper precast concrete column 20J is cylindrical, and the hollow part 25J is formed so as to penetrate the outer shell concrete part 23J of the upper precast concrete column 20J from above to below. Moreover, the lower precast concrete column 20 in this modified example has a plurality of recesses 81 recessed downward on the upper surface 23t of the outer shell concrete portion 23. Moreover, the upper precast concrete column 20J arranged on the upper side has a protrusion 82 protruding downward on the lower surface of the outer shell concrete portion 23J. When connecting the upper precast concrete column 20J to the lower precast concrete column 20, the protrusions 82 are inserted into the recesses 81, and the lower precast concrete column 20 and the upper precast concrete column 20J are joined while suppressing misalignment between the lower precast concrete column 20 and the upper precast concrete column 20J. As a result, the hollow portion 25 of the lower precast concrete column 20 and the hollow portion 25J of the upper precast concrete column 20J are continuous vertically, so that by pouring concrete into the hollow portion 25J of the upper precast concrete column 20J from above, a poured-in-place concrete portion 30 can be formed so that the upper and lower floors are integrated. In addition, the configurations described in the above embodiments can be selected or changed as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0043] 1 Concrete column structure 25 Hollow section 2 Concrete pillar 28 Recess 3 Structure 27 Communication passage 20 Precast concrete columns 29 Steel bar connectors 21 Column reinforcement 30 Cast-in-place concrete section 22 Shear reinforcement 100 Formwork equipment 23 Outer shell concrete section 110 Outer formwork 23d Side 120 Inner formwork 23t Top surface 130 Frame 23u Top of the closure (bottom of the hollow section) 135 volts 23f (Hollow section) Wall S Reinforcement

Claims

1. A precast concrete column, A column main reinforcement provided on the outer periphery side; A shear reinforcement bar provided so as to surround the column main reinforcement; An outer shell concrete portion formed to embed the column main reinforcement and the shear reinforcement; Equipped with A hollow portion is formed inside the concrete shell portion so as to communicate with the outside at the upper surface of the concrete shell portion and to extend in the vertical direction, A precast concrete column, characterized in that the outer shell concrete portion is formed solid below the hollow portion, and the lower side of the hollow portion is closed.

2. The concrete shell has a communication passage extending from the bottom surface of the hollow portion to a side surface of the concrete shell, connecting the hollow portion to the outside.

2. A precast concrete column according to claim 1.

3. A method for constructing a concrete column structure using the precast concrete column according to claim 1 or 2, comprising the steps of: Installing the precast concrete column on the upper surface of a structure; A step of casting concrete in place, which forms a cast-in-place concrete section by casting concrete in the hollow section of the precast concrete column, and integrating the cast-in-place concrete with the shell concrete section, In the step of installing the precast concrete pillar, A method for constructing a concrete column structure, comprising the steps of: connecting a reinforcing bar protruding upward from the top surface of the structure from below to a reinforcing bar connector that is embedded in the lower end of the outer concrete section and has an upper end to which the column main bar of the outer concrete section is connected, thereby connecting the column main bar and the reinforcing bar.

4. A formwork device for manufacturing a precast concrete column according to claim 1 or 2, An outer formwork that forms the outer shell of the precast concrete column; An inner formwork for forming the hollow portion of the precast concrete column; Equipped with The outer form is provided so that the precast concrete column is manufactured with its axis in a lateral direction; The inner formwork is provided so as to be movable in the axial direction from a portion of the outer formwork corresponding to the upper surface of the precast concrete column, A formwork device characterized in that a plurality of rectangular frame bodies are temporarily fixed with bolts to the surface of the inner formwork, spaced apart in the axial direction, for forming recesses in the wall surface of the hollow portion.

Images