Building structure

Abstract

To provide the structure of a building, in which an existing steel frame and a new steel frame can be connected easily even when an existing beam is shifted from a specified place.SOLUTION: The building structure 1 includes an existing steel frame 11 constituting an existing beam portion 10 of an underground skeleton 2 or a foundation skeleton, a new steel frame 21 having the same size as the existing steel frame 11 and constituting a new beam portion 20 of the underground skeleton 2 or the foundation skeleton, and a connecting steel frame 40 having a larger size than the existing steel frame 11 and the new steel frame 21 and joined to the existing steel frame 11 by welding at one end and joined to the new steel frame 21 by welding at the other end.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reinforced concrete building structure that reuses the underground structure and foundation structure of an existing building. [Background technology]

[0002] For example, when constructing a new reinforced concrete building such as an office building, hotel, or apartment building, it has been proposed to reuse the underground structure and foundation structure of an existing building and construct the new building on top of it, thereby shortening the construction period and reducing costs associated with the construction of the new building (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-142687 Summary of the Invention [Problem to be solved by the invention]

[0004] In cases where the new building is larger than the existing building, the existing building's underground structure and foundation structure can be reused, and part of the existing structure can be demolished and a new structure can be built that is connected to the existing structure. In this case, the existing beams of the existing underground structure or foundation structure are cut in half to expose the existing steel frame, and then the new steel frame of the new beams that make up the new underground structure or foundation structure must be welded to the existing steel frame of the existing beams, and then covered with concrete.

[0005] However, because the new steel frame of the new beam and the existing steel frame of the existing beam are the same size, there was a problem in that if the existing beam shifted from its specified position due to deformation over time of the underground structure or foundation structure of the existing building, it became difficult to connect the existing steel frame to the new steel frame.

[0006] The present invention was made in consideration of such problems, and its purpose is to provide a building structure in which existing steel frames and newly constructed steel frames can be easily connected even if the existing beams are shifted from their specified positions. [Means for solving the problem]

[0007] The building structure of the present invention is a reinforced concrete building structure, characterized in that it comprises an existing steel frame that constitutes the existing beam portion of the underground structure or foundation structure, a newly constructed steel frame of the same size as the existing steel frame that constitutes the newly constructed beam portion of the underground structure or foundation structure, and a connecting steel frame that is larger in size than the existing steel frame and the newly constructed steel frame, and is joined to the existing steel frame by welding at one end and to the newly constructed steel frame by welding at the other end.

[0008] In the building structure of the present invention, in the above configuration, it is preferable that the existing steel frame, the newly constructed steel frame, and the connecting steel frame are each formed of H-shaped steel, and that the width and thickness of the flange of the connecting steel frame are larger than the width and thickness of the flange of the existing steel frame and the newly constructed steel frame. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a building structure in which existing steel frames and newly constructed steel frames can be easily connected even if the existing beams are misaligned from their specified positions. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a main part of a building structure according to one embodiment of the present invention, as viewed from the front. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] This is a diagram showing an existing beam with the existing steel frame exposed. [Figure 4] This is a diagram showing the state in which new steel frame has been placed next to an existing beam with the existing steel frame exposed. [Figure 5] This is a diagram showing the state in which the existing steel frame and the newly constructed steel frame are joined by connecting steel frames. [Figure 6] This is a diagram showing the exposed parts of the existing steel frame and the newly constructed steel frame covered with concrete. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a building structure according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0012] 1 and 2, a building structure 1 according to one embodiment of the present invention is constructed by reusing the underground structure 2 and foundation structure (not shown) of an existing building, i.e., an underground structure 2, to form part of a building 3 in which an above-ground portion (not shown) is constructed on top of the underground structure 2. The building 3 is made of reinforced concrete.

[0013] The underground structure 2 is made of reinforced concrete and constructed underground together with a foundation structure (not shown). The underground structure 2 has an existing section 2a that reuses the underground structure of an existing building, and a newly constructed section 2b.

[0014] The existing portion 2a has a part of a beam that was used as a beam of the existing building, i.e., an existing beam portion 10. The existing beam portion 10 has an existing steel frame 11 and an existing concrete portion 12 that covers the existing steel frame 11.

[0015] In this embodiment, the existing steel frame 11 is formed of an H-shaped steel. That is, the existing steel frame 11 has an upper flange portion 11a, a lower flange portion 11b, and a web portion 11c between the upper flange portion 11a and the lower flange portion 11b. The existing concrete portion 12 has a rectangular cross section perpendicular to the horizontal direction, and covers the entire existing steel frame 11 from above, below, left, and right.

[0016] The new construction portion 2b has a newly constructed beam, i.e., a new beam portion 20. The new beam portion 20 has a newly constructed steel frame 21 and a newly constructed concrete portion 22 that covers the newly constructed steel frame 21. The new construction portion 2b also has a newly constructed column, i.e., a new column 23, and the new beam portion 20 is supported by the new column 23. The new steel frame 21 is joined at one end to an internal steel frame 24 of the new column 23, and the concrete portion 25 that covers the new column 23 is provided integrally with the new concrete portion 22.

[0017] In this embodiment, the new steel frame 21 is formed of an H-shaped steel beam. Specifically, the new steel frame 21 has an upper flange portion 21a, a lower flange portion 21b, and a web portion 21c between the upper flange portion 21a and the lower flange portion 21b. The upper flange portion 21a of the new steel frame 21 is welded to an upper diaphragm 27 of a joint portion 26 provided on the internal steel frame 24 of the new column 23, the lower flange portion 21b is welded to a lower diaphragm 28 of the joint portion 26, and the web portion 21c is welded to the side surface of the joint portion 26, thereby fixing the new steel frame 21 to the internal steel frame 24. The new concrete portion 22, like the existing concrete portion 12, has a rectangular cross section perpendicular to the horizontal direction and covers the entire top, bottom, left, and right sides of the new steel frame 21. The concrete portion 25 has a rectangular cross section perpendicular to the vertical direction and covers the entire front, back, left, and right sides of the internal steel frame 24.

[0018] Multiple reinforcing bars 30 are arranged inside the existing concrete section 12 and the new concrete section 22. As shown in FIG. 1 , the multiple reinforcing bars 30 are arranged to extend horizontally around the existing steel frame 11 and the new steel frame 21, respectively. Each reinforcing bar 30 includes an existing reinforcing bar portion 31 that was used in the beam of the existing building and a newly arranged reinforcing bar portion 32, and the existing reinforcing bar portion 31 and the new reinforcing bar portion 32 are joined longitudinally at joints 33 by pressure welding or mechanical welding. For convenience, only two reinforcing bars 30, one at the top and one at the bottom, are shown in FIG. 1 . However, multiple reinforcing bars other than the illustrated reinforcing bars 30 are arranged in appropriate directions and positions inside the existing concrete section 12 and the new concrete section 22. Furthermore, although not shown, multiple reinforcing bars are arranged in appropriate directions and positions in the concrete section 25 of the new column 23.

[0019] The existing steel frame 11 and the new steel frame 21 are connected to each other by a connecting steel frame 40. That is, the connecting steel frame 40 is placed between the existing steel frame 11 and the new steel frame 21, and one end of the connecting steel frame 40 is joined to an end of the existing steel frame 11 by welding, and the other end of the connecting steel frame 40 is joined to an end of the new steel frame 21 by welding, thereby forming the beams 4 of the underground structure 2.

[0020] In this embodiment, the connecting steel frame 40 is formed of an H-shaped steel. That is, the connecting steel frame 40 has an upper flange portion 40a, a lower flange portion 40b, and a web portion 40c between the upper flange portion 40a and the lower flange portion 40b. The connecting steel frame 40 connects the existing steel frame 11 and the new steel frame 21 by joining one end of the upper flange portion 40a to an end of the upper flange portion 11a of the existing steel frame 11 by welding, joining one end of the lower flange portion 40b to an end of the lower flange portion 11b of the existing steel frame 11 by welding, joining the other end of the upper flange portion 40a to an end of the upper flange portion 21a of the new steel frame 21 by welding, and joining the other end of the lower flange portion 40b to an end of the lower flange portion 21b of the new steel frame 21 by welding.

[0021] One end of the web portion 40c of the connecting steel frame 40 may be joined by welding to the end of the web portion 11c of the existing steel frame 11, and the other end of the web portion 40c of the connecting steel frame 40 may be joined by welding to the end of the web portion 21c of the newly constructed steel frame 21. A plate material 42 may be fixed to one surface of the web portions 11c, 40c as a backing by a plurality of fastening members 41 such as bolts and nuts so as to straddle the web portion 11c of the existing steel frame 11 and the web portion 40c of the connecting steel frame 40. A plate material 44 may be fixed to one surface of the web portions 21c, 40c as a backing by a plurality of fastening members 43 such as bolts and nuts so as to straddle the web portion 21c of the newly constructed steel frame 21 and the web portion 40c of the connecting steel frame 40. Note that in FIGS. 1 and 2, only some of the fastening members 41, 43 are indicated by reference numerals. Furthermore, in the existing steel frame 11, through holes for inserting fastening members 41 must be formed on-site, and because this work is cumbersome, the number of holes or fastening members 41 for fixing the plate materials 42 is kept to a minimum (three in the illustrated case). In contrast, in the new steel frame 21 and the connecting steel frame 40, through holes for inserting fastening members 41 can be formed in the factory where the new steel frame 21 or the connecting steel frame 40 is manufactured, so the number of holes or fastening members 43 for fixing the plate materials 44 is made greater (36 in the illustrated case) than the number of holes or fastening members 41 for fixing the plate materials 42. The number of holes or fastening members 41, 43 for fixing the plate materials 42, 44 can be changed as appropriate.

[0022] Here, in the building structure 1 according to this embodiment, the existing steel frame 11 and the new steel frame 21 are the same size, but the connecting steel frame 40 is larger in size than the existing steel frame 11 and the new steel frame 21. In other words, the existing steel frame 11 and the new steel frame 21 are formed from steel frames of the same standard dimensions, while the connecting steel frame 40 is formed from steel frames whose standard dimensions are larger than those of the existing steel frame 11 and the new steel frame 21.

[0023] In this embodiment, the width B1 (see FIG. 2) of the upper flange portion 40a and the lower flange portion 40b of the connecting steel frame 40 is wider (for example, +50 mm) than the width B2 (see FIG. 2) of the upper flange portion 11a and the lower flange portion 11b of the existing steel frame 11 and the upper flange portion 21a and the lower flange portion 21b of the new steel frame 21, and the thickness t1 (see FIG. 1) of the upper flange portion 40a and the lower flange portion 40b is thicker (for example, two sizes larger) than the thickness t2 of the upper flange portion 11a and the lower flange portion 11b of the existing steel frame 11 and the upper flange portion 21a and the lower flange portion 21b of the new steel frame 21. The height dimension of the connecting steel frame 40 is the same as the height dimension of the existing steel frame 11 and the new steel frame 21. The upper flange portion 40a and the lower flange portion 40b of the connecting steel frame 40, both end faces facing the existing steel frame 11 and the newly constructed steel frame 21, are inclined so that the upper side is away from the existing steel frame 11 or the newly constructed steel frame 21, and welding between the connecting steel frame 40 and the existing steel frame 11 or the newly constructed steel frame 21 is performed between the inclined both end faces and the end faces of the existing steel frame 11 or the newly constructed steel frame 21.

[0024] The connecting steel frame 40 is covered by the newly constructed concrete portion 22 together with the end portion of the existing steel frame 11 joined to the connecting steel frame 40 and the newly constructed steel frame 21 .

[0025] In this way, in the building structure 1 of this embodiment, in the reinforced concrete beam 4 in which the existing steel frame 11 and the newly constructed steel frame 21 are connected by the connecting steel frame 40, the existing steel frame 11 and the newly constructed steel frame 21 are made the same size, and the connecting steel frame 40 is made larger than the existing steel frame 11 and the newly constructed steel frame 21. Therefore, even if the existing part 2a of the underground frame 2, i.e., the existing steel frame 11, is shifted from the specified position due to deformation over time of the underground frame or foundation frame of the existing building, the connecting steel frame 40, which is larger in size than the existing steel frame 11 and the newly constructed steel frame 21, can absorb the positional shift of the existing steel frame 11 relative to the newly constructed steel frame 21 of the newly constructed part 2b, and the existing steel frame 11 and the newly constructed steel frame 21 can be easily connected by the connecting steel frame 40.

[0026] For example, if the existing steel frame 11 is horizontally misaligned relative to the specified position or the newly constructed steel frame 21, the width B1 of the upper flange portion 40a and lower flange portion 40b of the connecting steel frame 40 is wider than the width B2 of the upper flange portion 11a and lower flange portion 11b of the existing steel frame 11 and the upper flange portion 21a and lower flange portion 21b of the newly constructed steel frame 21, so that the upper flange portion 40a of the connecting steel frame 40 can be easily and reliably joined to the upper flange portion 11a of the existing steel frame 11 and the upper flange portion 21a of the newly constructed steel frame 21 by welding, and the lower flange portion 40b of the connecting steel frame 40 can be easily and reliably joined to the lower flange portion 11b of the existing steel frame 11 and the lower flange portion 21b of the newly constructed steel frame 21 by welding. At this time, the web portion 40c of the connecting steel frame 40 will shift horizontally relative to at least one of the web portion 11c of the existing steel frame 11 and the web portion 21c of the newly constructed steel frame 21, so filler plates (not shown) can be placed at appropriate positions between the web portions 11c, 21c, 40c and the plate materials 42, 44 to absorb the shift.

[0027] Furthermore, if the existing steel frame 11 is vertically misaligned relative to the specified position or the newly constructed steel frame 21, the thickness t1 of the upper flange portion 40a and lower flange portion 40b of the connecting steel frame 40 is thicker than the thickness t2 of the upper flange portion 11a and lower flange portion 11b of the existing steel frame 11 and the upper flange portion 21a and lower flange portion 21b of the newly constructed steel frame 21, so that the upper flange portion 40a of the connecting steel frame 40 can be easily and reliably joined to the upper flange portion 11a of the existing steel frame 11 and the upper flange portion 21a of the newly constructed steel frame 21 by welding, and the lower flange portion 40b of the connecting steel frame 40 can be easily and reliably joined to the lower flange portion 11b of the existing steel frame 11 and the lower flange portion 21b of the newly constructed steel frame 21 by welding.

[0028] The building structure 1 according to this embodiment can be constructed, for example, by the following procedure.

[0029] First, as shown in Fig. 3, a part of the underground skeleton 50 of the existing building is demolished, and in doing so, the existing beams 51 (existing steel frame 11 and existing reinforcing bar portion 31) are cut in the middle and the existing concrete portion 12 is chipped away to expose one end side portion of the existing steel frame 11 and the existing reinforcing bar portion 31 to the outside from the existing concrete portion 12. In addition, a hole 11d is formed in the web portion 11c of the existing steel frame 11.

[0030] Next, as shown in Fig. 4, the inner steel frame 24 and the new steel frame 21 are constructed adjacent to the existing beam 51. At this time, the end of the new steel frame 21 faces the end of the existing steel frame 11 with a predetermined gap therebetween.

[0031] Next, as shown in Figure 5, connecting steel frame 40 is placed between existing steel frame 11 and newly constructed steel frame 21, and one end of upper flange portion 40a of connecting steel frame 40 is welded to the end of upper flange portion 11a of existing steel frame 11, one end of lower flange portion 40b of connecting steel frame 40 is welded to the end of lower flange portion 11b of existing steel frame 11, the other end of upper flange portion 40a of connecting steel frame 40 is welded to the end of upper flange portion 21a of new steel frame 21, and the other end of lower flange portion 40b of connecting steel frame 40 is welded to the end of lower flange portion 21b of new steel frame 21. In addition, web portion 40c of connecting steel frame 40 is welded and joined to web portion 11c of existing steel frame 11 and web portion 21c of new steel frame 21 using backing plates 42, 44 and fastening members 41, 43. As a result, the existing steel frame 11 and the newly constructed steel frame 21 are connected by the connecting steel frame 40. After the existing steel frame 11 and the newly constructed steel frame 21 are connected by the connecting steel frame 40, the newly constructed steel bar portion 32 is joined to the end of the existing steel bar portion 31 by pressure welding or mechanically.

[0032] Next, as shown in Figure 6, concrete is poured to cover the existing steel frame 11 and the exposed portions of the existing reinforcing bar portions 31 from the existing concrete portion 12, the connecting steel frame 40, and the new steel frame 21 to form the new concrete portion 22, and concrete is poured around the inner steel frame 24 to form a concrete portion 25 integral with the new concrete portion 22. This allows the construction of a portion of the underground skeleton 2, which includes a beam 4 in which the steel frame portion, in which the existing steel frame 11 and the new steel frame 21 are connected by the connecting steel frame 40, and the reinforcing bars 30 are embedded in the new concrete portion 22, and a new column 23 in which the inner steel frame 24 is embedded in the concrete portion 25.

[0033] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0034] For example, in the above embodiment, the present invention is applied to the beams 4 that constitute the underground skeleton 2 of the building 3, but the present invention may also be applied to beams (foundation beams) that constitute the foundation skeleton of the building 3.

[0035] Furthermore, in this embodiment, the existing steel frame 11, the new steel frame 21, and the connecting steel frame 40 are each formed of H-shaped steel, but this is not limiting and they may be formed of steel frames of other shapes. [Explanation of symbols]

[0036] 1. Building structure 2 Underground structure 2a Existing part 2b New section 3. Building 4 beams 10 Existing beam section 11 Existing steel frame 11a Upper flange part 11b Lower flange part 11c Web section 11d hole 12 Existing concrete section 20 New beam section 21 New steel frame 21a Upper flange part 21b Lower flange part 21c Web section 22 Newly constructed concrete section 23 New pillar 24 Internal steel frame 25 Concrete Section 26 Joint 27 Upper diaphragm 28 Lower diaphragm 30 Reinforced concrete 31 Existing rebar section 32 Newly installed rebar section 33 Joint 40 Connected Steel Frame 40a Upper flange part 40b Lower flange part 40c web section 41 Fastening members 42 Plate material 43 Fastening members 44 Plate material 50 Underground structure 51 Existing beam B1 width B2 width t1 thickness t2 thickness

Claims

1. A building structure made of reinforced concrete, The existing steel frame that constitutes the existing beam portion of the underground structure or foundation structure, A new steel frame having the same size as the existing steel frame, which constitutes a new beam portion of the underground frame or the foundation frame; A building structure characterized by having a connecting steel frame that is larger in size than the existing steel frame and the newly constructed steel frame, and is joined to the existing steel frame by welding at one end and to the newly constructed steel frame by welding at the other end.

2. The existing steel frame, the new steel frame, and the connecting steel frame are each formed of H-shaped steel, The building structure according to claim 1 , wherein the width and thickness of the flanges of the connecting steel frame are larger than the width and thickness of the flanges of the existing steel frame and the new steel frame.

Images