Beam construction method for floor extension

Abstract

To provide a beam construction method for floor extension which has excellent workability by smoothly positioning and joining a new beam at an installation position of an existing member, while eliminating lifting of the new beam by an operator and enhancing work safety, in constructing a beam for floor extension at an open ceiling of an existing building.SOLUTION: A beam construction method for floor extension for constructing beams B1, B2 for floor extension with respect to an open ceiling of an existing building includes a new beam construction step of, out of a girder B1 and a beam B2 which are a plurality of new steel beams crossing each other, with respect to a floor extension area ZA with respect to the open ceiling, both end parts of the girder B1 are joined to existing steel members G3, G4 of the existing building, one end of the beam B2 is joined to the girder B1, and the other end is joined to existing members G1, G2. In the new beam construction step, at two points of the existing members G1, G2, a rope R is directly or indirectly mounted, and by a lifting instrument W mounted on the rope R, the new beam B1 is lifted and joined to the existing members G3, G4.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for constructing beams for floor expansion. [Background technology]

[0002] In existing buildings with a void, renovations are sometimes carried out to add floor space to the void, for example, when an additional family member is living together. In such renovations, new steel beams (expansion beams) are installed in the expanded area of ​​the void, and flooring is then installed on the new beams. The construction of these new beams is carried out in a way that the new steel beams that intersect with each other are joined to the existing steel members (existing beams, etc.) of the existing building.

[0003] In the above-mentioned method of joining a new steel beam to an existing steel member, a commonly used method is, for example, for a worker to stand on a stepladder installed on the first floor, lift the new beam to the installation position on the existing member, and then join the end of the new beam to the existing member while maintaining this position.

[0004] This increases the risk of the new beams falling while being held up by workers, posing a major issue in terms of work safety.In addition, there is also the issue of workability, as it is difficult for workers to smoothly align the bolt holes of the new beams with those of the existing members when they lift the beams.

[0005] In view of the above, there is a need for a method of constructing beams for expanding floor space in an atrium of an existing building that eliminates the need for workers to lift the newly installed beams, thereby increasing work safety, while allowing the new beams to be smoothly aligned to the installation positions of existing components, resulting in excellent workability.

[0006] Here, Patent Document 1 proposes a method for expanding the floor of a reinforced concrete structure. This method for expanding the floor of a reinforced concrete structure involves erecting multiple girders made of lightweight box-shaped steel pipes in parallel between opposing internal vertical wall surfaces of a void space in a reinforced concrete structure, stretching fire-resistant lightweight materials such as foamed concrete panels on the upper and lower surfaces of the girders, covering the upper surface of the upper fire-resistant lightweight material with a floor plywood, and covering the lower surface of the lower fire-resistant lightweight material with a ceiling base board, thereby forming an expansion floor in the void space. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 5-25944 Summary of the Invention [Problem to be solved by the invention]

[0008] The method for expanding floor spaces of a reinforced concrete structure described in Patent Document 1 is literally a method for expanding floor spaces of a reinforced concrete structure, and therefore does not propose a construction method for expanding floor spaces that eliminates the need for workers to lift newly constructed beams in construction to join existing steel frame members to existing steel frame members in an open space in an existing building, thereby improving work safety, as described above.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method for constructing beams for expanding floor space in an atrium of an existing building, which eliminates the need for workers to lift the newly installed beams, thereby increasing work safety, while allowing the new beams to be smoothly aligned and joined to the installation positions of existing components, resulting in excellent workability. [Means for solving the problem]

[0010] In order to achieve the above object, one aspect of the method for designing a beam for floor expansion according to the present invention is to A method for constructing an expansion beam in an existing building, comprising: A new beam construction process is provided for connecting both ends of a large beam and a small beam, which are a plurality of mutually intersecting steel-framed newly constructed beams, to existing members of the steel-framed structure of the existing building, connecting one end of the small beam to the large beam, and connecting the other end of the small beam to the existing member, for the expanded area for the atrium. The new beam construction process is characterized in that a rope is attached directly or indirectly to two points of the existing member, and the new beam is lifted by a lifting device attached to the rope and joined to the existing member.

[0011] According to this embodiment, a rope is attached directly or indirectly to two points on the existing component, and the new beam is lifted using a lifting device attached to the rope and joined to the existing component, eliminating the need for workers to lift the new beam and increasing work safety, while the new beam can be smoothly aligned and joined to the installation position of the existing component, thereby improving workability.

[0012] Here, "attaching a rope directly or indirectly to two points of an existing member" includes not only directly attaching both ends of the rope to two existing members, but also indirectly attaching the rope to an existing member by attaching one end of the rope to another member, such as a support, that is attached to the existing member. New beams include main and secondary beams. Existing members include existing beams and existing columns. Furthermore, ropes include steel wires and chains in addition to ropes and cordage.

[0013] After the new beam is raised to the installation level by a lifting device attached to a rope, the end of the new beam and the existing member are joined by bolting or welding. Here, by using a one-sided bolt to join from the atrium side, in cases where it is not possible to reach the back side of the existing member, for example, when there is a room in use adjacent to the existing member, it is preferable to insert the bolt from the atrium side into a bolt hole already opened in the existing member or a bolt hole newly opened from the atrium side, so that the construction does not affect the room.

[0014] In addition, another aspect of the method for constructing beams for floor expansion according to the present invention is as follows: A tensioner is disposed at a midpoint of the rope, and tensions the rope using the tensioner.

[0015] According to this embodiment, the newly constructed beam can be lifted in a stable position by tensioning the rope using a tensioning device located midway along the rope, which is preferable.

[0016] In addition, another aspect of the method for constructing beams for floor expansion according to the present invention is as follows: Attaching a support directly or indirectly to the existing member; The method is characterized in that the rope is attached to the support and the lifting device attached to the rope is positioned at a position higher than the installation level of the new beam to be joined to the existing member.

[0017] According to this embodiment, a rope is attached to a support that is directly or indirectly attached to the existing member, and a lifting device attached to the rope is positioned at a position higher than the installation level of the new beam to be joined to the existing member, so that the new beam can be lifted to the installation level of the new beam and joined to the existing member.

[0018] Here, "the support pillar is directly or indirectly attached to the existing member" includes not only the support pillar being directly attached to the existing member, but also the support pillar being indirectly attached to the existing member by fixing the support pillar to another member, such as a support pillar fixing jig, which is attached to the existing member.

[0019] In addition, another aspect of the method for constructing beams for floor expansion according to the present invention is as follows: The method is characterized in that a support pillar fixing jig is attached to the existing member, and the support pillar is attached to the support pillar fixing jig.

[0020] According to this aspect, by attaching the support to which the end of the rope is attached to the support fixing jig attached to the existing member, the ease of installation is improved when the rope to which the hoisting device for hoisting the new beam is attached is installed at a level higher than the installation level of the new beam. For example, when the support is directly attached to the existing member, the length of the support becomes longer and the weight becomes heavier, which may reduce the ease of attaching the support to the existing member and the ease of handling the support, but such problems are solved by the method of attaching the support to the support fixing jig.

[0021] In addition, another aspect of the method for constructing beams for floor expansion according to the present invention is as follows: The rope is attached to the two pillars, the lifting device is attached to the rope, and the two pillars are attached to the corresponding pillar fixing jigs simultaneously or sequentially.

[0022] According to this embodiment, after both ends of the rope, to which the lifting device and tensioning device are attached, are attached to two pillars, two workers can simultaneously attach the two pillars to the corresponding pillar fixing jigs, or one worker can attach them sequentially, thereby efficiently attaching both ends of the rope, to which the lifting device is attached, to two points on the existing member.

[0023] In another aspect of the method for constructing floor extension beams according to the present invention, The two points are points where a straight line passing through the longitudinal center or its vicinity of the newly constructed beam to be lifted intersects with the existing building, and the lifting device is installed at or near the center.

[0024] According to this embodiment, the two points at which the ends of the rope are attached to the existing components are the points where a straight line passing through the longitudinal center of the newly constructed beam or its vicinity intersects with the existing building, and by installing a lifting device at or near this center of the rope, the newly constructed beam can be lifted stably while suppressing the rattle of the lifting device that lifts the newly constructed beam.

[0025] In another aspect of the method for constructing floor extension beams according to the present invention, The pillar or the pillar fixing jig is attached to the existing member by bolting from the open space side using a one-sided bolt.

[0026] According to this embodiment, the pillars or pillar fixing jigs are attached to the existing components by bolting them from the open-air side with one-sided bolts. As described above, the bolts can be inserted from the open-air side into bolt holes that have already been opened in the existing components or into bolt holes that have been newly opened from the open-air side, which is preferable because it prevents the construction from affecting rooms currently in use.

[0027] Existing components such as existing beams may have bolt holes provided at predetermined intervals for fixing a jig for installing a safety net when constructing a new existing beam, so the bolt holes already provided in the existing component may be used. Alternatively, if there are no bolt holes in the existing component at the location where you want to install the support fixing jig, etc., the end of the new beam can be aligned to the installation position of the existing component while the new beam is suspended by a lifting device, and the bolt holes in the new beam can be used as a guide to construct bolt holes in the existing component.

[0028] Furthermore, in the case of welding, not only must the work be performed by a qualified person, but there are also issues such as the quality of the work depending on the skill of the worker, and furthermore, there is a possibility that the insulation material or wooden base laid inside the existing member may ignite during welding, and if welding is performed after removing surrounding members such as the ceiling and facings for safety, the work area will be wider than necessary, which is not desirable.In contrast, by using a one-sided bolt to perform the bolt connection from the atrium side, the various issues inherent to welding can be resolved. Effect of the Invention

[0029] As can be understood from the above explanation, according to the method for constructing beams for floor expansion of the present invention, when constructing beams for floor expansion in an open space in an existing building, it is possible to provide a method for constructing beams for floor expansion that is easy to work with by eliminating the need for workers to lift the newly installed beams, thereby increasing work safety, while also allowing the newly installed beams to be smoothly aligned and joined to the installation positions of existing components. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a floor plan of the second floor of an example of an existing building to which the method for constructing floor expansion beams according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method according to the embodiment. [Diagram 3] 2, this is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method according to the embodiment. [Figure 4] Continuing from FIG. 3, this is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method according to the embodiment. [Diagram 5] This is a diagram illustrating the state in which a lifting device is attached to a rope whose both ends are attached to two supports. [Figure 6] 4, this is an explanatory diagram for explaining the new beam construction process of the floor expansion beam construction method according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an example of a floor expansion beam construction method according to an embodiment will be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[0032] [Method of constructing beams for floor expansion according to the embodiment] An example of a floor expansion beam construction method according to the embodiment will be described with reference to Fig. 1 to Fig. 6. Here, Fig. 1 is a floor plan of the second floor of an example of an existing building to which the floor expansion beam construction method according to the embodiment is applied. Fig. 2 to Fig. 4 and Fig. 6 are explanatory diagrams for explaining the new beam construction process of the floor expansion beam construction method according to the embodiment, and Fig. 5 is a diagram for explaining a state in which a lifting device is attached to a rope whose both ends are attached to two pillars.

[0033] Below, we will explain an example of an existing building to which the extension beam construction method of the embodiment can be applied, using a steel-framed, multi-story detached house with an open void.

[0034] The second floor of the building to be constructed, shown in Figure 1, has a stairwell and free space around it. In the example shown, the stairwell is provided above the porch, entrance, and living room on the first floor (all of which are shown in parentheses as they are on the first floor). On the second floor, surrounding the stairwell, there is an existing beam G1 on the outdoor side between the first and second floors, an existing beam G2 on the indoor side facing the existing beam G1, and another pair of existing beams G3 and G4 perpendicular to these.

[0035] As shown in Fig. 2, a rectangular area in plan view surrounded by four existing beams G1 to G4 is set as an expansion area ZA. In this expansion area ZA, a plurality of new steel beams that intersect with each other are sequentially erected according to the load area of ​​the expansion area ZA.

[0036] Specifically, as shown in FIG. 3, a beam assembly BU consisting of two new beams B1, B2 intersecting each other is constructed as a beam assembly BU capable of supporting the floor load of the entire area of ​​the expanded area ZA.

[0037] In the illustrated example, of the two new beams B1 and B2, the other new beam B1 (winning beam) to which the end of the other new beam B2 is attached becomes the main beam, and the new beam B2 (losing beam) to which one end is attached becomes the minor beam. In construction, the main beam B1 is constructed first in the expansion area ZA, and then the set BU is constructed in the order of constructing the two minor beams B2.

[0038] To explain the method of constructing beams for floor expansion in detail, first, as shown in FIG. 4, the main beam B1 is placed on the floor surface of the first floor in a position where it can be lifted.

[0039] Here, an example of equipment for lifting the main girder B1 and attaching it to the existing girder G1, G2 will be described with reference to Fig. 5. The equipment shown in the illustrated example is also used to lift the sub-girder B2, and it is attached to the existing girder G3, G4 and the main girder B1.

[0040] A worker attaches a support fixing jig J to each of the opposing existing beams G1, G2, for example, using a stepladder or the like placed on the first floor floor.

[0041] The support pillar fixing jig J is formed by welding a single pipe C1 having a diameter of, for example, 48.6 mm to a steel fixing plate E. The fixing plate E has a bolt hole H2 formed therein.

[0042] A worker aligns bolt hole H2 of fixing plate E with bolt hole H1 pre-drilled in existing beams G1, G2, and attaches pillar fixing jig J to main girder B1 by inserting one-sided bolt SB in the X1 direction from the atrium side. If bolt hole H1 does not exist in the existing beams G1, G2 at the position where pillar fixing jig J is to be attached, bolt hole H1 may be drilled at the desired position from the atrium side.

[0043] Here, the support pole fixing jig can have various forms other than the illustrated example, such as a form in which a steel plate that is inserted into the inside of a support pole made of a single pipe is connected to a steel fixing plate, or a form in which a single pipe clamp that grips the support pole is connected to a steel fixing plate.

[0044] In addition, there are various types of one-sided bolts SB that can be used, but the type shown in the figure is one in which the roll plate is freely rotatable around the rotation axis at the tip, and is inserted into bolt holes H2, H1 that communicate from the atrium side.When the roll plate protrudes from bolt hole H2 to the outside of the main girders G1, G2, the roll plate rotates around the rotation axis, and the entire plate assumes an L shape, and the roll plate engages with the main girders G1, G2.

[0045] Although not shown, other types of one-sided bolts include those that include a washer and a leg-spreading member, and after the leg-spreading member is inserted into the bolt holes of multiple joined members, the leg-spreading member opens to the side and approaches the washer when the bolt is tightened, and the multiple joined members are joined by the washer and the open leg-spreading member. Still another type is one in which a bolt is screwed into the bolt holes of multiple joined members to join the multiple joined members.

[0046] In this way, by attaching the pillar fixing jig J to the existing beams G1, G2 by bolting it from the open-air side with a one-sided bolt SB, the bolt can be inserted into the bolt hole H1 of the existing beams G1, G2 from the open-air side, which is preferable as it prevents the construction from affecting rooms currently in use.

[0047] For example, FIG. 4 shows positions P1 and P2 at which a pair of support fixing jigs J are attached to existing beams G1 and G2.

[0048] The installation position P1 of the pillar fixing jig is located in a position where it is not possible to reach the back of the existing beam G1 (jointing from the back side is not possible), so construction can be done by bolting from the open space side using one-sided bolt SB.

[0049] On the other hand, the pillar fixing jig installation position P2 is located behind the existing beam G2, where there is free space available for use by residents. Similarly, since workers cannot reach the back side of the existing beam G2, construction can be performed by bolting from the open space side using a one-sided bolt SB.

[0050] On the first floor floor, fasteners F on both ends of a rope R are hooked to hooks Ca at the heads of a pair of pillars C2, and an electric winch W (an example of a hoisting device) is attached to the rope R, and, for example, two workers simultaneously lift each pillar C2 and stand on a stepladder to insert the lower end of the pillar C2 into the single pipe C1 of the pillar fixing jig J in the X2 direction, thereby spanning the rope R to which the electric winch W is attached via the pair of pillar fixing jigs J and the pillars C2 to two points (P1, P2) of the opposing existing beams G1, G2. Here, a method in which one worker sequentially attaches the corresponding pillars C2 to each pillar fixing jig J may also be used.

[0051] The support column C2 is formed of, for example, a single pipe of φ42.7 mm, and is firmly fixed without rattling when inserted into the single pipe C1 of φ48.6 mm as described above. A stopper ST made of a pin, reinforcing bar, a relatively large-diameter short single pipe, etc. is attached to the lower part of the support column C2, and when the lower part of the support column C2 is inserted into the single pipe C1 to a position where it is stable in terms of strength, the insertion of the support column C2 is stopped by the stopper ST.

[0052] Here, the attachment position of the electric winch W relative to the rope R is set to the center position of the rope R (a position at a distance t from a pair of supports C2), and it is preferable to take anti-slip measures (not shown) to prevent the electric winch W from shifting from this center position.

[0053] A tensioner T is provided midway along the rope R (near the fastener F on the right side in the illustrated example), and when the electric winch W is used to lift the girder B1, the rope R is tensioned by the tensioner T and stretched around a pair of supports C2. For example, the rope R extending from the tensioner T can be hung down to a height within reach of a worker on the first floor, and the worker can pull on the rope R to tension it.

[0054] In Fig. 5, the dashed line connecting the opposing existing beams G1 and G2 represents the girder B1 that will be spanned between the existing beams G1 and G2. Since the girder B1 will be spanned between the existing beams G1 and G2, the electric winch W that lifts the girder B1 needs to be positioned at a higher level than the installation level of the girder B1.

[0055] As shown in the illustrated example, by attaching the support C2 to which the end of the rope R is attached to the support fixing jig J attached to the existing beams G1, G2, the ease of installation is improved when installing the rope R to which the electric winch W is attached at a level higher than the installation level of the main girder B1. For example, a method of directly attaching the support to the existing beams G1, G2 may be used, but the length of the support may become longer than necessary, and in that case, the weight of the support may also become heavy, which may reduce the ease of attaching the support to the existing beams G1, G2 and the ease of handling the support.

[0056] In contrast, by attaching the pillar fixing jig J to the existing beams G1, G2 and attaching the pillar C2 to each pillar fixing jig J as in the illustrated example, the pillar C2 is prevented from becoming excessively long, and the pillar C2 is easy to install and easy to handle.

[0057] As shown in Fig. 4, the mounting positions P1, P2 for the pair of support pillar fixing jigs are the intersection points where a straight line L1 (virtual line) passing through the center O1 of the main girder B1, which is placed in a position where it can be lifted straight up on the first floor, intersects with the opposing existing beams G1, G2. Such support pillar fixing jig mounting positions P1, P2 can be set in various ways, but as described above, they may be set at a location where a bolt hole H1 is already drilled, or at a location where the workability during lifting construction is good. In the latter case, if the bolt hole H1 does not exist in the existing beams G1, G2, the bolt hole H1 can be drilled.

[0058] The rope R tensioned by the tensioner T is positioned directly on the straight line L1 shown in FIG.

[0059] By lifting the center O1 of the main girder B1 placed on the first floor with an electric winch W attached to the center of a rope R stretched between a pair of supports C2, the main girder B1 can be lifted to the installation level in a stable posture while suppressing the lateral swaying of the main girder B1, and both ends of the main girder B1 can be smoothly aligned to the installation positions of the existing beams G3 and G4.

[0060] With the girder B1 suspended by the electric winch W, a worker standing, for example, on a stepladder joins both ends of the girder B1 to a pair of existing beams G3, G4 by bolting or welding using bolts or one-sided bolts (joints D3, D4 in Figure 3).

[0061] Here, even when connecting the main girder B1 to the existing beams G3, G4, if workers are unable to reach behind the existing beams G3, G4 to work, or if it is considered not to use a welded connection due to the issues involved, a bolt connection using a one-sided bolt from the atrium side is applied.

[0062] Next, as shown in Figure 6, the same method as for lifting the main beam B1 and joining it to the existing beams G3 and G4 is applied to lifting the two secondary beams B2 and joining each secondary beam B2 to the existing beam G2 and the main beam B1, and to joining the existing beam G1 to the main beam B1.

[0063] Regarding the upper secondary beam B2 in Figure 6, the pillar fixing jig J used when lifting the main beam B1 is replaced and installed at the pillar fixing jig mounting positions P3 and P4 where the straight line L2 passing through the center O2 of the secondary beam B2 placed on the first floor floor surface intersects with the existing beams G3 and G4.

[0064] Similarly, the pillar C2 to which both ends of the rope R to which the electric winch W is attached, which was used to lift the main girder B1, is rearranged and attached to a pair of pillar fixing jigs J, and the secondary beam B2 is lifted to the installation level using the electric winch W, and both ends of the secondary beam B2 are joined to the main girder B1 and the existing beam G2.

[0065] Next, with regard to the lower small beam B2 in Figure 6, the pillar fixing jig J used when lifting the previously installed small beam B2 is replaced and installed at the pillar fixing jig mounting positions P5, P6 where the straight line L3 passing through the center O3 of the small beam B2 placed on the first floor floor surface intersects with the existing beams G3, G4.

[0066] Similarly, the pillar C2 to which both ends of the rope R to which the electric winch W is attached, which was used to lift the previously installed secondary beam B2, is rearranged and attached to a pair of pillar fixing jigs J, and the secondary beam B2 is lifted to the installation level using the electric winch W. Both ends of the rope R are then joined to the main beam B1 and the existing beam G1, and a beam assembly BU consisting of the main beam B1 and secondary beam B2 is constructed in the expanded area ZA (this concludes the new beam construction process).

[0067] According to the illustrated method of constructing beams for floor expansion, a rope R is attached directly or indirectly to two points on the existing members G1 to G4, and the new beams B1, B2 are lifted by a lifting device W attached to the rope R and joined to the existing members G1 to G4, thereby eliminating the need for workers to lift the new beams B1, B2 and improving work safety, while the new beams B1, B2 can be smoothly aligned and joined to the installation positions of the existing members G1 to G4, thereby improving workability.

[0068] In addition, the present invention is not limited to the configuration shown here, and may be implemented in other embodiments in which other components are combined with the configurations and the like of the above-mentioned embodiment. In this regard, the present invention may be modified within the scope of the gist of the present invention, and may be appropriately determined according to the application form. [Explanation of symbols]

[0069] ZA: Expansion area B1: Newly installed beam (large beam, beam for floor expansion) B2: Newly installed beam (small beam, beam for floor expansion) BU: Beams (for floor expansion) G1: Existing members (existing beams, existing permanent beams, channel steel) G2: Existing members (existing beams, channel steel) G3: Existing members (existing beams, channel steel) G4: Existing members (existing beams, channel steel) GU: Existing unit beam (existing beam) D1, D2, D3, D4: Joints R: Rope W: Lifting device (electric winch) T: Tension machine F: Zipper J: Pillar fixing jig C1: Single tube E: Fixing plate C2: Pillar Ca: Hook H1,H2 N: Nut SB: One-sided bolt P1~P6: Pillar fixing jig installation positions L1, L2, L3: Straight line (imaginary line) O1: Center of girder O2, O3: Center of the trabecula

Claims

1. A method for constructing an expansion beam in an existing building, comprising: A new beam construction process is provided for connecting both ends of a large beam and a small beam, which are a plurality of mutually intersecting steel-framed newly constructed beams, to existing members of the steel-framed structure of the existing building, connecting one end of the small beam to the large beam, and connecting the other end of the small beam to the existing member, for the expanded area for the atrium. The method for constructing beams for floor expansion, characterized in that in the new beam construction process, a rope is attached directly or indirectly to two points of the existing member, and the new beam is lifted by a lifting device attached to the rope and joined to the existing member.

2. 2. The method for constructing a beam for floor extension according to claim 1, characterized in that a tensioner is interposed at a midpoint of the rope, and the rope is tensioned by the tensioner.

3. Attaching a support directly or indirectly to the existing member; The method for constructing beams for floor expansion described in claim 2, characterized in that the rope is attached to the support and the lifting device attached to the rope is positioned at a position higher than the installation level of the newly constructed beam to be joined to the existing member.

4. The method for constructing beams for floor expansion according to claim 3, characterized in that a pillar fixing jig is attached to the existing member, and the pillar is attached to the pillar fixing jig.

5. The method for constructing beams for floor expansion described in claim 4, characterized in that the rope is attached to two of the pillars, the lifting device is attached to the rope, and the two pillars are attached to the corresponding pillar fixing jigs simultaneously or sequentially.

6. The method for constructing beams for floor expansion described in claim 1, characterized in that the two points are points where a straight line passing through the longitudinal center or its vicinity of the newly constructed beam to be lifted intersects with the existing building, and the lifting device is installed at or near the center.

7. The method for constructing beams for floor expansion according to claim 3 or 4, characterized in that the support or the support fixing jig is attached to the existing member by bolting from the open space side using a one-sided bolt.

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