Precast concrete beams, support support structures, and support construction and removal methods

Abstract

To provide a precast concrete beam, a timbering receiving structure, and a method for constructing and removing timbering, capable of extracting a receiving member for supporting the timbering and reusing the receiving member.SOLUTION: A precast concrete beam 12 is constructed so that a sheath tube 14 is longitudinally buried in a concrete part 30 and a top end 14 A of the sheath tube 14 is lower than a top end 38 A of a slab concrete 38 cast on the beam.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a precast concrete beam, a support support structure, and a support construction and removal method. [Background technology]

[0002] Conventionally, a support structure for supporting the beam formwork of the beams of the upper floor has been proposed.

[0003] Patent Document 1 listed below discloses a beam formwork support structure in which a PC (precast) beam member is provided with a support part that supports the beam formwork of the beams of the upper floor. The support part includes a formwork support member that supports the beam formwork from below, and a support member that is provided to connect the formwork support member and the PC beam member. A J-shaped steel member with a nut attached to its upper end is embedded in the PC beam member, and a support part is fixed to the nut at the upper end of this steel member, and the support member is connected to the support part (see, for example, Figure 8 of Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-53650 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the beam formwork support structure described in Patent Document 1 above, after removing the beam formwork unit equipped with a formwork support member and a support member, it is necessary to cut off the area near the nut at the upper end of the steel material protruding from the top edge of the slab concrete.

[0006] In consideration of the above, the present invention aims to provide a precast concrete beam, a support support structure, and a method for constructing and removing a support that allows the support member that supports the support to be removed and reused. [Means for solving the problem]

[0007] The precast concrete beam described in the first embodiment has a hollow pipe embedded vertically in the concrete part of the beam, and the top of the hollow pipe is lower than the top of the slab concrete poured on top of the beam, or is at the same height as the top of the slab concrete.

[0008] According to the first aspect of the precast concrete beam, a hollow pipe is embedded vertically in the concrete of the beam. A support member is inserted into this hollow pipe, and the top of the support member serves as a support for the support of the beam on the upper floor. This allows the support for the beam on the upper floor to be installed before the floor concrete is poured on the construction floor. Next, after the support is removed, the receiving member is not embedded in the slab concrete, or the embedded length is short, so it can be removed from the hollow pipe and reused. Furthermore, since the top of the hollow pipe is lower than or at the same level as the top of the slab concrete poured on top of the beam, the hollow pipe does not protrude from the top of the slab concrete, eliminating the need to cut the hollow pipe (i.e., work involving fire).

[0009] The support support structure described in the second aspect comprises a precast concrete beam described in the first aspect assembled to a column, a support member inserted into the hollow tube, and a connecting member attached to the support member to which a support member supporting the precast concrete beam on the upper floor is connected.

[0010] According to the second aspect of the shoring support structure, a hollow pipe is embedded in the precast concrete beam of the lower floor, which is attached to the column, and a support member is inserted into the hollow pipe. A connecting member is attached to the support member, and a support member that supports the precast concrete beam of the upper floor is connected to the connecting member. Therefore, the support for the precast concrete beam of the upper floor can be installed before the floor concrete of the construction floor is poured. Next, after the support is removed, the receiving member is not embedded in the slab concrete, or the embedded length is short, so it can be removed from the hollow pipe and reused. Furthermore, since the top of the hollow pipe is lower than or at the same level as the top of the slab concrete poured on top of the beam, the hollow pipe does not protrude from the top of the slab concrete, eliminating the need to cut the hollow pipe (i.e., work involving fire).

[0011] The support construction and removal method described in the third aspect includes the steps of assembling a precast concrete beam of a lower floor, which has a hollow pipe embedded vertically in the concrete part of the beam, to a column; inserting a support member into the hollow pipe; attaching a connecting member to the support member; connecting a support member that supports the precast concrete beam of an upper floor to the connecting member; arranging slab reinforcement for the lower floor; pouring slab concrete onto the upper surface of the lower floor and the upper surface of the precast concrete beam; after the slab concrete has hardened, removing the support member and the connecting member and extracting the support member from the hollow pipe; and filling the hollow pipe with concrete or mortar to finish the lower floor.

[0012] According to the third aspect of the shoring construction and removal method, a precast concrete beam on a lower floor, which has a hollow pipe embedded vertically in the concrete of the beam, is assembled to a column. A support member is inserted into the hollow pipe embedded vertically in the concrete of the precast concrete beam on the lower floor. A connecting member is then attached to the support member. Then, a support member that supports the precast concrete beam on the upper floor is connected to the connecting member. This allows the support for the precast concrete beam on the upper floor to be installed before the slab concrete on the lower floor is poured. Next, the slab reinforcement for the lower floor is placed. Then, slab concrete is poured onto the upper surface of the lower floor and the upper surface of the precast concrete beams. After the slab concrete has hardened, the support members and connecting members are removed, and the support members are extracted from the hollow pipes. At this time, by not embedding the support members in the slab concrete or by shortening their embedding length, the support members can be removed from the hollow pipes and reused. In addition, by making the top of the hollow pipe lower or the same as the top of the slab concrete, the hollow pipe does not protrude from the top of the slab concrete, and cutting of the hollow pipe (i.e., work using fire) is not required. The hollow pipe is sealed by injecting concrete or mortar. [Effects of the Invention]

[0013] According to the present disclosure, the support member supporting the shoring can be removed from the hollow tube and the support member can be reused. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view showing the support receiving structure of the first embodiment. [Figure 2] 1A to 1E are configuration diagrams showing an example of a shoring construction and removal method to which the shoring support structure of the first embodiment is applied. [Figure 3] (A) is a front view showing a sheath pipe embedded in a precast concrete beam, (B) is a cross-sectional view showing the sheath pipe, and (C) is a cross-sectional view showing an example of a method for fixing a sheath pipe embedded in a precast concrete beam. [Figure 4] 2 is a cross-sectional view showing an example of a sheath tube, a bundle member, and a connecting member used in the support receiving structure of the first embodiment. FIG. [Figure 5] (A) is a front view showing the lower connecting member, and (B) is a front view showing a cross section of a portion of the lower connecting member and upper connecting member attached to the top of the beam, with a support member attached to the upper connecting member. [Figure 6] 1 is an elevation view showing an example of a structure to which the shoring support structure of the first embodiment is applied. FIG. [Figure 7] 10(A) to 10(E) are diagrams illustrating an example of a comparative example of a method for constructing and removing a support structure. DETAILED DESCRIPTION OF THE INVENTION

[0015] The embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, elements that are less relevant to the present invention are omitted. Note that the direction indicated by the arrow UP shown appropriately in each drawing is the upward direction in the vertical direction.

[0016] [First embodiment] A shoring support structure and a shoring construction and removal method according to a first embodiment will be described with reference to Figs.

[0017] <Overall structure of support structure> Fig. 1 shows a shoring support structure 10 according to a first embodiment. As shown in Fig. 1, the shoring support structure 10 includes a precast concrete beam (i.e., a PCa beam) 12 assembled to a column 20 (see Fig. 6), and a sheath pipe 14 embedded vertically in a concrete portion 30 of the precast concrete beam 12. The shoring support structure 10 also includes a beam 16 inserted into the sheath pipe 14, and a connecting member 18 attached to the beam 16 and to which a shoring member 22 supporting a beam on an upper floor is connected. Here, the sheath pipe 14 is an example of a hollow pipe, and the beam 16 is an example of a support member.

[0018] FIG. 6 shows a structure 100 to which a shoring support structure 10 is applied. As shown in FIG. 6, the structure 100 has a plurality of columns 20, to each of which a precast concrete beam 12 of the lower floor is attached. The precast concrete beams 12 attached to the columns 20 on both sides form part of the longitudinal direction of the beam 110 of the lower floor. The precast concrete beam 12 of the lower floor is provided with the shoring support structure 10. A beam 16 is inserted into a sheath pipe 14 embedded in the concrete portion 30 of the precast concrete beam 12 of the lower floor, and a connecting member 18 is attached to the beam 16. A shoring member 22 is connected to the connecting member 18. The shoring member 22 supports the precast concrete beam 12 of the upper floor.

[0019] (precast concrete beams) As shown in Fig. 1, the precast concrete beam 12 is fabricated in advance in a factory, and a sheath pipe 14 is embedded vertically (in the up-down direction in this embodiment) in a concrete portion 30. In this embodiment, the precast concrete beam 12 is a half precast concrete beam, and forms a longitudinal portion of a beam 110 of a lower floor (e.g., a construction floor) that is assembled to a column 20 (see Fig. 6).

[0020] The precast concrete beam 12 is provided with reinforcing bars 32. The reinforcing bars 32 include a plurality of first reinforcing bars 32A arranged in the longitudinal direction, a plurality of second reinforcing bars 32B arranged to surround the first reinforcing bars 32A, and a third reinforcing bar 32C arranged in the vertical direction and having both ends locked to the first reinforcing bars 32A. When the precast concrete beam 12 is fabricated in a factory, the lower sides of the reinforcing bars 32 (i.e., the lower sides of the first reinforcing bars 32A, second reinforcing bars 32B, and third reinforcing bars 32C) are embedded in the concrete portion 30, and the upper sides of the reinforcing bars 32 (i.e., the upper sides of the first reinforcing bars 32A, second reinforcing bars 32B, and third reinforcing bars 32C) are exposed to the outside of the concrete portion 30.

[0021] As an example, protrusions 30A protruding upward are provided on both sides in the width direction of the upper part of the concrete part 30. The protrusions 30A are bodies that support the spancrete (slab) 36.

[0022] A slab concrete 38 is poured on-site on top of the precast concrete beam 12 assembled to the column 20 (see FIG. 6). In this embodiment, when the slab concrete 38 is poured, the top end (upper end) 14A of the sheath pipe 14 is configured to be lower than the top end (upper end) 38A of the slab concrete 38.

[0023] (sheath tube) The sheath tube 14 is a tubular body having a length in the direction toward the center, and is embedded vertically (vertically in this embodiment) in the concrete portion 30 of the precast concrete beam 12. The inner diameter of the sheath tube 14 is larger than the outer diameter of the bundle 16, allowing the bundle 16 to be inserted inside the sheath tube 14. The sheath tube 14 has the function of supporting the bundle 16 inserted from above. The outer diameter of the sheath tube 14 is, for example, φ50 mm.

[0024] The upper side of the sheath pipe 14 is exposed upward from the concrete portion 30 of the precast concrete beam 12. In other words, the height of the top end 14A of the sheath pipe 14 is higher than the height of the upper surface of the concrete portion 30 of the precast concrete beam 12 and the upper ends of the reinforcing bars 32 (i.e., the upper ends of the first reinforcing bar 32A, the second reinforcing bar 32B, and the third reinforcing bar 32C).

[0025] Figures 3(A) and (B) show an example of a sheath pipe 14. Figure 3(C) shows an example of a fixing structure for the sheath pipe 14 when manufacturing a precast concrete beam 12 in a factory. As shown in Figure 3(A), a bottom cover 14B is provided at the lower longitudinal end of the sheath pipe 14, which is closed to prevent concrete from flowing in. A through hole 15 is formed in the bottom cover 14B. A nut 50 is attached to the underside of the bottom cover 14B, aligning the position of the through hole 15 with the position of the screw hole (see Figure 3(C)).

[0026] As shown in Fig. 3(B), a holding part 52 is attached to the upper part of the sheath tube 14. The holding part 52 is provided with a through-hole 53 through which a rod-shaped fixing jig 54 (see Fig. 3(C)) for fixing the sheath tube 14 is inserted.

[0027] As shown in FIG. 3(C), the fixing jig 54 is provided with a threaded portion 54A. The fixing jig 54 is inserted into the through-hole 53 and inserted into the sheath tube 14, and the tip of the threaded portion 54A of the fixing jig 54 is screwed into the nut 50. Then, a bolt 60 inserted into a through-hole 59 of the support frame 58 is screwed into a nut 56 attached to the top of the fixing jig 54, thereby fixing and supporting the sheath tube 14 to the support frame 58. In this state, concrete is poured to produce the precast concrete beam 12. Note that the reinforcing bars 32 (i.e., the first reinforcing bar 32A, the second reinforcing bar 32B, and the third reinforcing bar 32C) are omitted from FIG. 3(C).

[0028] The fixing structure of the sheath pipe 14 during the production of the precast concrete beam 12 is not limited to the above structure and can be modified.

[0029] (bundle material) The bundle 16 has the function of receiving a support (not shown) having support members 22. In this embodiment, the axial length of the bundle 16 is longer than the longitudinal (axial) length of the sheath tube 14. When the bundle 16 is inserted into the sheath tube 14 from above, the lower end 16B of the bundle 16 comes into contact with the bottom cover 14B of the sheath tube 14. In this state, the upper end 16A of the bundle 16 is exposed upward from the top end 14A of the sheath tube 14.

[0030] As an example, the bundle 16 is a reinforcing bar. In this embodiment, the bundle 16 is a threaded bar having a spiral protrusion on the outer circumferential surface. The largest outer diameter of the bundle 16 is, for example, 46 mm.

[0031] (connecting member) The connecting member 18 has the function of connecting the strand 16 and the support member 22. As shown in Figures 4 and 5(B), in this embodiment, the connecting member 18 includes a lower connecting member 42 attached to the top of the strand 16, and an upper connecting member 44 attached on top of the lower connecting member 42.

[0032] As shown in Fig. 5(A), the lower connecting member 42 includes a plate-shaped base plate 46 and a tubular portion 48 extending downward from the base plate 46. As an example, the base plate 46 is generally rectangular in plan view, and has through-holes 46A on both sides in the width direction through which fasteners are inserted. As an example, the through-holes 46A are provided in two locations. For example, the base plate 46 has a length of 180 mm on one side in the vertical direction and a length of 140 mm on one side in the horizontal direction in plan view.

[0033] The tubular portion 48 is generally cylindrical and has an inner peripheral surface 48A. The inner diameter of the inner peripheral surface 48A is larger than the outer diameter of the bundle 16. This allows the tubular portion 48 of the lower connecting member 42 to be inserted into the upper end 16A of the bundle 16. When the tubular portion 48 is inserted into the upper end 16A of the bundle 16, the lower surface of the base plate 46 contacts the end surface of the upper end 16A of the bundle 16. In other words, the lower connecting member 42 is attached to the upper end 16A of the bundle 16 by inserting the tubular portion 48 onto the upper end 16A of the bundle 16 and contacting the base plate 46 with the upper end 16A of the bundle 16. The vertical length from the upper surface of the base plate 46 to the lower end of the tubular portion 48 is, for example, 85 mm. The insertion depth of the bundle 16 inserted into the tubular portion 48 is, for example, 76 mm.

[0034] The upper connecting member 44 includes a base plate 46 and a tubular portion 48 extending upward from the base plate 46. The upper connecting member 44 is vertically symmetrical to the lower connecting member 42 and is made up of similar materials. In this embodiment, the lower connecting member 42 uses the same materials as the upper connecting member 44, but inverted in the vertical direction.

[0035] (Shoring components) The shoring member 22 has the function of supporting the precast concrete beams 12 (see Figure 6) on the upper floor. The shoring member 22 is connected to the upper connecting member 44. As an example, the shoring member 22 is a substantially cylindrical tubular body. The inner diameter of the shoring member 22 is slightly larger than the outer diameter of the tubular portion 48. As a result, the lower end of the shoring member 22 is inserted onto the outside of the tubular portion 48 of the upper connecting member 44, and the end face of the lower end of the shoring member 22 contacts the base plate 46 of the upper connecting member 44. In other words, the shoring member 22 is attached to the upper connecting member 44 while being inserted onto the tubular portion 48 of the upper connecting member 44.

[0036] <Support construction and removal methods> Next, an example of a method for constructing and removing shoring will be described.

[0037] 2(A) to 2(E) show an example of a method for constructing and removing support according to this embodiment. As shown in Fig. 2(A), a precast concrete beam 12 is fabricated in a factory in advance, with a sheath pipe 14 embedded vertically in a concrete portion 30, and the precast concrete beam 12 is transported to a construction site. The upper side of the sheath pipe 14 embedded in the concrete portion 30 of the precast concrete beam 12 is exposed from the concrete portion 30.

[0038] This precast concrete beam 12 is assembled to the column 20 (see Figure 6) of the structure 100 as part of the beam on the lower floor. Although not shown in the figure, first, support for the beam on the lower floor is constructed, and the support is chucked up to support the precast concrete beam 12, thereby assembling the precast concrete beam 12 on the lower floor to the column 20. Mortar is then poured into the joint between the precast concrete beam 12 and the column 20 to join them. Furthermore, spancrete 36 (see Figure 1) is placed on the protruding portion 30A of the precast concrete beam 12 on the lower floor.

[0039] At this point, construction of the support for the upper floor begins. As shown in Figure 2(B), the beam 16 is inserted into the sheath pipe 14 that is embedded vertically in the concrete part 30 of the precast concrete beam 12 of the lower floor. In this state, the upper end 16A of the beam 16 is exposed upward from the top end 14A of the sheath pipe 14.

[0040] Next, the connecting member 18 is attached to the top of the bundle 16 (see Figure 2(B)). In this embodiment, the tubular portion 48 of the lower connecting member 42 is inserted into the upper end 16A of the bundle 16, and the base plate 46 of the lower connecting member 42 is brought into contact with the upper end 16A of the bundle 16 (see Figure 5(B), etc.). Furthermore, the base plate 46 of the upper connecting member 44 is placed on the base plate 46 of the lower connecting member 42, and these two base plates 46 are fixed together with fasteners 70 such as bolts and nuts. In this embodiment, the lower connecting member 42 has the same configuration as the upper connecting member 44, and the lower connecting member 42 is inserted into the upper end 16A of the bundle 16 with the top and bottom reversed.

[0041] Next, the shoring members 22 that support the precast concrete beams 12 (see Figure 6) on the upper floor are connected to the connecting members 18. In this embodiment, the lower end of the shoring member 22 is inserted into the outside of the tubular portion 48 of the upper connecting member 44, and the lower end of the shoring member 22 is brought into contact with the base plate 46 of the upper connecting member 44 (see Figure 5(B) etc.). This connects the shoring member 22 to the upper connecting member 44. Although not shown, other members that make up the shoring on the upper floor are attached to the shoring member 22. Then, assembly of the columns 20 and precast concrete beams 12 (see Figure 6) on the upper floor begins.

[0042] Additionally, slab reinforcement (not shown) for the lower floor is arranged near the precast concrete beams 12 of the lower floor. Then, as shown in FIG. 2(C), slab concrete 38 is poured on the upper surface of the lower floor floor and the upper surface of the precast concrete beams 12. At this time, the tops of the sheath pipes 14 and the beams 16 are covered with cloth or the like before the slab concrete 38 is poured, thereby preventing the slab concrete 38 from entering the inside of the sheath pipes 14. In this embodiment, the top end 14A of the sheath pipes 14 is set lower than the top end 38A of the slab concrete 38. As an example, a recess 62 recessed downward is formed around the top end 14A of the sheath pipes 14 on the upper surface of the slab concrete 38. For example, the top end 14A of the sheath pipes 14 is approximately 10 mm lower than the top end 38A of the slab concrete 38, allowing the slab concrete 38 to be poured up to the edge of the top end 14A of the sheath pipes 14.

[0043] As shown in FIG. 2(D), after the slab concrete 38 has hardened, the support members 22 and connecting members 18 are removed, and the struts 16 are extracted from the sheath tubes 14. At this time, the top ends 14A of the sheath tubes 14 and the struts 16 are not embedded in the slab concrete 38, so the struts 16 can be extracted from the sheath tubes 14. The extracted struts 16, connecting members 18, and support members 22 can be reused (repurposed) to construct support for the beams on the upper floor. In other words, in this embodiment, everything except the sheath tubes 14 can be reused. For example, the support members 22 and connecting members 18 may be removed after the precast concrete beams 12 (FIG. 6) on the upper floor are assembled to the columns 20, the slab reinforcement for the upper floor floor is arranged, and the slab concrete for the upper floor is poured.

[0044] 2(E), the lower floor is finished by filling the recessed portion 62 of the concrete slab 38 and the inside of the sheath pipe 14 with concrete 64. Note that instead of concrete 64, mortar may be filled into the recessed portion 62 of the concrete slab 38 and the inside of the sheath pipe 14.

[0045] <Action and effect> Next, the operation and effects of this embodiment will be described.

[0046] As shown in Figure 1, etc., the precast concrete beam 12 of this embodiment has a sheath pipe 14 buried vertically in the concrete section 30, and the top end 14A of the sheath pipe 14 is lower than the top end 38A of the slab concrete 38 poured on the beam and the lower floor.

[0047] In the above-described precast concrete beam 12, beams 16 are inserted into sheath pipes 14 embedded in concrete section 30, and the tops of beams 16 serve as supports for support members 22 that support the precast concrete beams 12 on the upper floor. This allows the support for the beams on the upper floor to be installed before the floor concrete on the lower floor, which is the construction floor, is poured.

[0048] Next, after the support members 22 and the connecting members 18 are removed, the bundles 16 are no longer embedded in the slab concrete 38, so they can be extracted from the sheath tubes 14 and reused.

[0049] Furthermore, since the top end 14A of the sheath pipe 14 is lower than the top end 38A of the slab concrete 38 poured on top of the beam, the sheath pipe 14 does not protrude from the top end 38A of the slab concrete 38, eliminating the need to cut the sheath pipe 14 (i.e., work involving fire).

[0050] In the shoring support structure 10 of this embodiment, a sheath pipe 14 is embedded vertically in the concrete portion 30 of a precast concrete beam 12 on a lower floor that is assembled to a column 20 of a structure 100 (see FIG. 6), and a beam 16 is inserted into the sheath pipe 14. A connecting member 18 is attached to the beam 16, and a shoring member 22 that supports the precast concrete beam 12 on an upper floor is connected to the connecting member 18. Therefore, shoring for the precast concrete beam 12 on the upper floor (see FIG. 6) can be installed before the floor concrete of the construction floor is poured.

[0051] Next, after the support members 22 and the connecting members 18 are removed, the bundles 16 are no longer embedded in the slab concrete 38, so they can be extracted from the sheath tubes 14 and reused.

[0052] Furthermore, since the top end 14A of the sheath pipe 14 is lower than the top end 38A of the slab concrete 38 poured on top of the beam, the sheath pipe 14 does not protrude from the top end 38A of the slab concrete 38, eliminating the need to cut the sheath pipe 14 (i.e., work involving fire) (see Figure 2(D)).

[0053] In the shoring construction and removal method of this embodiment, a precast concrete beam 12 of the lower floor shown in FIG. 2(A) is assembled to a column 20 of a structure 100. A sheath pipe 14 is embedded vertically in the concrete portion 30 of the precast concrete beam 12 of the lower floor. Next, a beam 16 is inserted into the sheath pipe 14 embedded in the concrete portion 30 of the precast concrete beam 12 of the lower floor (see FIG. 2(B)). Furthermore, a connecting member 18 is attached to the beam 16. As an example, a lower connecting member 42 is attached to the top of the beam 16, and an upper connecting member 44 is attached to the lower connecting member 42 (see FIG. 2(B)). Then, a shoring member 22 that supports the precast concrete beam 12 of the upper floor is connected to the upper connecting member 44 that constitutes the connecting member 18 (see FIG. 2(B)). Therefore, the shoring for the precast concrete beam 12 of the upper floor can be installed before the slab concrete 38 of the lower floor is poured. In addition, there is no need for space to store the support members 22 on the lower construction floor.

[0054] Next, the slab reinforcement for the lower floor is arranged. Then, slab concrete 38 is poured onto the upper surface of the lower floor and the upper surface of the precast concrete beams 12 (see Figure 2(C)). After the slab concrete 38 has hardened, the support members 22 and connecting members 18 are removed, and the bundles 16 are extracted from the sheath pipes 14. At this time, by ensuring that the bundles 16 are not embedded in the slab concrete 38, the bundles 16 can be extracted from the sheath pipes 14 and reused (see Figure 2(D)).

[0055] In addition, the top end 14A of the sheath pipe 14 is made lower than the top end 38A of the concrete slab 38. This prevents the sheath pipe 14 from protruding from the top end 38A of the concrete slab 38, eliminating the need for cutting the sheath pipe 14 (i.e., work involving fire). Furthermore, the lower floor is finished by injecting concrete 64 or mortar into the sheath pipe 14 to seal it.

[0056] A comparative example of a method for constructing and removing shoring will now be described with reference to Fig. 7. In Fig. 7, the same components as those in this embodiment are denoted by the same reference numerals.

[0057] 7(A), in the comparative example of shoring support structure 200, when a precast concrete beam 202 is manufactured in a factory, a beam 204 is embedded (driven) vertically into a concrete section 30. An upper end 204A of the beam 204 is exposed above the concrete section 30. A plate-shaped support section 206 extending in a direction perpendicular to the axial direction of the beam 204 is provided at the upper end 204A of the beam 204.

[0058] As shown in Figure 7(B), a support member 210 that supports the precast concrete beam 202 on the upper floor is attached to the upper surface of the receiving portion 206 via a base plate 208. Although not shown in the figure, for example, the support member 210 is attached to the outside of a cylindrical portion that extends upward from the base plate 208.

[0059] Next, the slab reinforcement for the lower floor is arranged, and as shown in Figure 7(C), slab concrete 214 is poured onto the upper surface of the lower floor and the upper surface of the precast concrete beams 202. At this time, a recess 214B recessed downward is provided around the beam 204 at the top end 214A of the slab concrete 214.

[0060] As shown in Figure 7(D), after the slab concrete 214 has hardened, the support members 210 and base plate 208 are removed, and the upper side of the beam 204 is cut from the recessed portion 214B using fire. The cut upper side of the beam 204 is disposed of. The support members 210 and base plate 208 are used to support the precast concrete beams 202 on the upper floor.

[0061] Next, as shown in FIG. 7(E), concrete 216 is filled into the recessed portion 214B of the concrete slab 214, thereby completing the lower floor.

[0062] In the comparative example of the support construction and removal method, the pile members 204 are buried vertically in the concrete section 30, so the pile members 16 exposed above the slab concrete 214 must be cut using fire work.

[0063] In contrast, in the support construction and removal method of this embodiment, the bundle 16 is inserted into the sheath pipe 14 embedded in the concrete portion 30 of the precast concrete beam 12, so the bundle 16 can be removed and reused. In addition, the sheath pipe 14 does not protrude from the top end 38A of the slab concrete 38, so cutting the sheath pipe 14 (i.e., hot work) is not required.

[0064] [Example of change] In the above embodiment, the bundle 16 is inserted into the sheath pipe 14 embedded in the concrete portion 30 of the precast concrete beam 12, but the present disclosure is not limited to this configuration. For example, a single-pipe handrail may be inserted into the sheath pipe 14 embedded in the concrete portion 30 of the precast concrete beam 12 as a safety facility after the precast concrete beam 12 is assembled to the column 20. For example, a single-pipe handrail with an outer diameter of φ48.6 mm may be inserted into the sheath pipe 14.

[0065] 〔supplementary explanation〕 In the above embodiment, the top end 14A of the sheath pipe 14 is lower than the top end 38A of the slab concrete 38 poured on the precast concrete beam 12, but the present disclosure is not limited to this configuration. For example, the top end 14A of the sheath pipe 14 may be set to approximately the same height as the top end 38A of the slab concrete 38 poured on the precast concrete beam 12. In this case, after the support is removed, the embedded length of the pile members 16 in the slab concrete 38 is short, so the pile members 16 can be removed from the sheath pipe 14 and reused.

[0066] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to such embodiments, and that various other embodiments are possible within the scope of the present invention. [Explanation of symbols]

[0067] 12 Precast concrete beams 14 Sheath tube (hollow tube) 14A Top 16 Bundle material (receiving member) 18 Connecting member 20 pillars 22 Shoring components 30 Concrete Section 30A protrusion 38 Slab Concrete 38A Top 42 Lower connecting member (connecting member) 44 Upper connecting member (connecting member)

Claims

1. A precast concrete beam in which a hollow pipe with its lower end closed by a bottom cap is buried vertically in the concrete portion of a beam, and the top of the hollow pipe is made lower than the top of the beam, which is at the same height as the slab, or is made at the same height as the top of the beam, by the slab concrete poured on top of the concrete portion of the beam.

2. The precast concrete beam of claim 1 assembled to a column; a receiving member inserted into the hollow tube; A connection member attached to the receiving member and to which a support member supporting a precast concrete beam of an upper floor is connected; A support structure with a support structure.

3. A process of assembling precast concrete beams on the lower floor, each with a hollow tube embedded vertically in the concrete of the beam, to the columns; inserting a receiving member into the hollow tube; attaching a connecting member to the receiving member; a step of connecting support members supporting precast concrete beams of an upper floor to the connecting members; The process of placing reinforcement bars on the slab of the lower floor; Pouring slab concrete on the upper surface of the lower floor and on the upper surface of the precast concrete beam; After the slab concrete has hardened, removing the support members and the connecting members and extracting the receiving members from the hollow pipes; filling the hollow pipe with concrete or mortar to finish the lower floor; A method for constructing and removing a support structure.

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