Method for connecting steel beams

Abstract

To provide a connection method of a steel frame beam capable of easily connecting the steel frame beam to an existing structure of reinforced concrete construction or reinforced steel frame concrete construction of an existing building.SOLUTION: A method of connecting a steel frame beam 20 to an existing structure 10 of reinforced concrete construction or reinforced steel frame concrete construction of an existing building, the method comprising: a chipping step of chipping a part of an existing concrete portion 12 of the existing structure 10 to form a chipped portion 14; a steel frame beam arranging step of arranging a new steel frame beam 20 having a headed stud 24 fixed to a leading end thereof such that the headed stud 24 is positioned in the chipped portion 14; and a new concrete portion placing step of placing a new concrete portion 15 in the chipped portion 14 to embed the headed stud 24 in the new concrete portion 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for connecting steel beams to an existing structure of reinforced concrete or reinforced steel concrete in an existing building. [Background technology]

[0002] For example, when constructing a new 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 constructing 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 underground structure and foundation structure of the existing building can be reused and the new underground structure or foundation structure can be connected to the existing underground structure or foundation structure. However, in this case, it is necessary to connect steel beams to the existing reinforced concrete or reinforced steel concrete structure that makes up the existing underground structure or foundation structure, i.e., the existing beams or columns, and this connection can be difficult.

[0005] The present invention has been made in consideration of such problems, and its purpose is to provide a method for connecting steel beams that can easily connect steel beams to existing reinforced concrete or reinforced steel concrete structures of existing buildings. [Means for solving the problem]

[0006] The method for connecting steel beams of the present invention is a method for connecting steel beams to an existing structure made of reinforced concrete or reinforced steel concrete in an existing building, and is characterized by comprising: a chipping process in which a portion of the existing concrete section of the existing structure is chipped to form a chipped section; a steel beam placement process in which a new steel beam with a headed stud fixed to its tip is placed so that the headed stud is positioned in the chipped section; and a new concrete section pouring process in which a new concrete section is poured into the chipped section and the headed stud is embedded in the new concrete section.

[0007] In the steel beam connection method of the present invention, in the above configuration, the existing structure is an existing beam made of reinforced concrete and equipped with existing steel frames formed from H-shaped steel, and in the chipping process, it is preferable to chip off the existing concrete portion on one side of the web portion of the existing steel frame to form the chipped portion. [Effects of the Invention]

[0008] According to the present invention, a method for connecting steel beams can be provided that can easily connect steel beams to existing reinforced concrete or reinforced steel concrete structures of existing buildings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a main part of a building structure constructed using a steel beam connecting method according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] A cross-sectional view showing the state of the existing beam before it was reused. [Figure 4] 1A and 1B show the state of an existing beam in which a chipped portion has been formed by a chipping process, in which (a) is a cross-sectional view and (b) is a plan view. [Figure 5] This is a diagram showing the state in which a newly constructed steel beam with a headed stud fixed to its tip is placed next to an existing beam in which a notch has been formed in the steel beam placement process. [Figure 6]This is a diagram showing the state in which a new concrete section has been poured into the chipped section through the new concrete section pouring process. [Figure 7] This is a diagram showing the state in which concrete has been poured on top of the existing beams and steel beams to form a new floor. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a method for connecting steel beams according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0011] The building structure 1 shown in Figures 1 and 2 is constructed by reusing the underground structure 2 and foundation structure (not shown) of an already constructed building, i.e., an existing building, on top of which the above-ground portion (not shown) is constructed.It has an existing beam 10 as an existing structure that constitutes the underground structure 2 of the existing building, and a steel beam 20 connected to the existing beam 10 using a steel beam connecting method according to one embodiment of the present invention.

[0012] The underground structure 2 is made of reinforced concrete and constructed underground together with a foundation structure (not shown). The existing beams 10 that make up the underground structure 2 have existing steel frames 11, existing concrete sections 12 that cover the existing steel frames 11, and multiple reinforcing bars 13 buried in the existing concrete sections 12. Note that the reinforcing bars 13 are not shown in Figure 2.

[0013] 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 in a portion other than the portion where the steel beam 20 is connected, and covers the entire existing steel frame 11 from above, below, left, and right. A plurality of reinforcing bars 13 are arranged appropriately, for example, arranged in a direction along the existing steel frame 11 and as hoop reinforcement surrounding the existing steel frame 11.

[0014] At the portion of the existing beam 10 where the steel beam 20 is connected, a recessed chipped portion 14 is formed by chipping (scraping) a portion of the existing concrete portion 12. In this embodiment, the chipped portion 14 is formed by chipping off the portion of the existing concrete portion 12 surrounded by the upper flange portion 11a, the lower flange portion 11b, and the web portion 11c of the existing steel frame 11 on the side where the steel beam 20 is connected, while leaving most of the portion below the lower flange portion 11b unchipped, thereby forming a recessed shape. The chipped portion 14 is filled with the new concrete portion 15, and the new concrete portion 15 is integrated with the existing concrete portion 12. In other words, the portion of the existing beam 10 where the steel beam 20 is connected is formed with the same cross-sectional shape as the other portion where the chipped portion 14 is not provided, because the chipped portion 14 is filled with the new concrete portion 15.

[0015] In this embodiment, an existing floor (floor slab) 16 is integrally provided with the existing beam 10. The existing floor 16 is formed of concrete integrally with the existing concrete portion 12, and extends horizontally from the upper end of the existing beam 10. Note that the existing beam 10 may have a configuration in which the existing floor 16 is not integrally formed.

[0016] The steel beam 20 was newly installed when reusing the underground structure 2 and foundation structure of an existing building, and is connected to the existing beam 10 at the tip on the left side in Figure 1 to form a minor beam of the building structure 1.

[0017] In this embodiment, the steel beam 20 is formed of an H-shaped steel. That is, the steel beam 20 has an upper flange portion 20a, a lower flange portion 20b, and a web portion 20c between the upper flange portion 20a and the lower flange portion 20b. Two rectangular connecting plates 21 are fixed to the ends of the web portion 20c in a parallel orientation to the web portion 20c by fastening members 22 such as bolts and nuts. A base plate 23 is welded to the ends of these connecting plates 21 in a perpendicular and parallel orientation to the base plate 23. Three headed studs 24 are fixed to the base plate 23 by welding or the like, spaced apart from each other in the vertical direction, so that they protrude from the base plate 23 toward the web portion 11c of the existing steel frame 11. Note that the number of headed studs 24 fixed to the base plate 23 is not limited to three. Furthermore, the arrangement of the headed studs 24 fixed to the base plate 23 is not limited to the above.

[0018] The steel beam 20 is connected to the existing beam 10 by embedding three headed studs 24 in a newly constructed concrete section 15 that fills the chipped section 14 of the existing beam 10. In this embodiment, the base plate 23 is placed on the surface of the newly constructed concrete section 15 so that the surface on which the connecting plate 21 is fixed is flush with the surface of the newly constructed concrete section 15, and the three headed studs 24 are entirely embedded within the newly constructed concrete section 15. With this configuration, the vertical load of the steel beam 20 connected to the existing beam 10 is supported by the existing beam 10 via the fastening members 22, connecting plate 21, base plate 23, headed studs 24, and new concrete section 15. Furthermore, because the headed studs 24 are embedded within the new concrete section 15, they are prevented from coming out of the new concrete section 15. In addition, in this embodiment, the tip portions (head portions) of the three headed studs 24, which are the left ends in Figure 1, are all positioned between the upper flange portion 11a and the lower flange portion 11b of the existing steel frame 11, so the vertical load of the steel beam 20 can be more firmly supported in the portion of the newly constructed concrete section 15 between the upper flange portion 11a and the lower flange portion 11b of the existing steel frame 11.

[0019] In this embodiment, a new concrete floor (floor slab) 25 is integrally formed with the existing beam 10. To provide the new floor 25, a portion of the existing concrete section 12 of the existing beam 10 above the upper flange 11a of the existing steel frame 11 and to the right of the web portion 11c in FIG. 1 is chipped along the longitudinal direction of the existing beam 10 to provide a secondary chipped portion 17 for the new floor. The new floor 25 is integrally connected to the existing beam 10 so that a portion of its left end in FIG. 1 fills the secondary chipped portion 17 on the upper flange 11a. The new floor 25 extends horizontally from the upper end of the existing beam 10 and is supported by a steel beam 20. A plurality of headed studs 26 are fixed to the upper surface of the upper flange 20a of the steel beam 20 by welding or the like, spaced apart along the longitudinal direction of the upper flange 20a, each protruding upward from the top surface of the upper flange 20a. These headed studs 26 are embedded in the new floor 25, and the new floor 25 is fixed to the steel beams 20 via the headed studs 26. Note that the new floor 25 may not be placed on top of the steel beams 20.

[0020] Next, a procedure for connecting steel beams 20 to existing beams 10 using the steel beam connecting method according to this embodiment when constructing a building structure 1 having the above configuration will be described.

[0021] The existing beam 10 shown in Figure 3 is the existing beam 10 before it is reused, i.e., before the steel beam 20 is connected, and has an existing steel frame 11, an existing concrete section 12 that covers the entire existing steel frame 11, and reinforcing bars 13, and the existing concrete section 12 in the part where the steel beam 20 is to be connected has a rectangular cross section.

[0022] In the method for connecting steel beams according to this embodiment, first, in the chipping process, a portion of the existing concrete portion 12 of the existing beam 10 shown in Figure 3 is chipped to form a chipped portion 14 in the portion of the existing concrete portion 12 of the existing beam 10, as shown in Figure 4.

[0023] In this embodiment, in the chipping process, the portion of the existing concrete section 12 surrounded by the upper flange portion 11a, the lower flange portion 11b, and the web portion 11c of the existing steel frame 11 is chipped away on the side where the steel beam 20 is connected (the right side in FIG. 4 ), while leaving most of the portion below the lower flange portion 11b unchipped, thereby forming a concave chipped portion 14. In the chipped portion 14, the underside of the upper flange portion 11a of the existing steel frame 11, the top surface of the lower flange portion 11b, and the right side surface of the web portion 11c in FIG. 4 are exposed to the outside. A portion of the reinforcing bars 13 of the existing beam 10 is cut off while protruding from the existing concrete section 12.

[0024] In this embodiment, in order to install a new floor 25 on top of the steel beam 20, the portion of the existing concrete section 12 above the upper flange portion 11a of the existing steel frame 11 and to the right of the web portion 11c in Figure 4 is cut along the longitudinal direction of the existing beam 10 to provide a secondary cutout portion 17.

[0025] Next, as shown in FIG. 5, in the steel beam placement process, a new steel beam 20 with headed studs 24 fixed to its tip is placed so that the headed studs 24 are located in the chipped section 14. In this embodiment, the steel beam 20 is placed in a desired orientation so that the tip portions (head portions) of the three headed studs 24, which are the left ends in FIG. 4, of the three headed studs 24 are located between the upper flange portion 11a and the lower flange portion 11b of the existing steel frame 11 in the chipped section 14. The headed studs 24 can be fixed to the tip of the steel beam 20 in advance using a connecting plate 21, fastening members 22, and base plate 23. Alternatively, new reinforcing bars 13 may be pressure-welded or mechanically joined to a portion of the reinforcing bars 13 that were cut from the existing beam 10 while protruding from the existing concrete section 12, and then placed in the chipped section 14.

[0026] Next, as shown in Figure 6, in the new concrete portion pouring process, new concrete portion 15 is poured into chipped portion 14, and headed studs 24 are embedded in new concrete portion 15. New concrete portion 15 may be poured so as to fill entire chipped portion 14. Once new concrete portion 15 poured into chipped portion 14 has hardened, steel beam 20 is connected to existing beam 10 via fastening members 22, connecting plate 21, base plate 23, headed studs 24, and new concrete portion 15. In this way, building structure 1 is constructed in which new steel beam 20 is connected to existing beam 10.

[0027] In this embodiment, after the new concrete section pouring process, as shown in Figure 7, the secondary recess 17 is filled and concrete is poured so that it extends above the steel beam 20 connected to the existing beam 10 to provide a new floor 25.

[0028] As described above, according to the method for connecting steel beams of this embodiment, in the chipping process, a portion of the existing concrete section 12 of the existing beam (existing structure) 10 is chipped off to form the chipped section 14, and in the steel beam placement process, a new steel beam 20 with a headed stud 24 fixed to its tip is placed so that the headed stud 24 is located in the chipped section 14, and in the new concrete section pouring process, a new concrete section 15 is poured into the chipped section 14 and the headed stud 24 is embedded in the new concrete section 15, thereby connecting the steel beam 20 to the existing beam 10, and therefore the steel beam 20 can be easily connected to the existing beam 10 of an existing building.

[0029] Furthermore, in this embodiment, the existing structure is an existing beam 10 made of reinforced concrete and equipped with an existing steel frame 11 formed from H-shaped steel, and in the chipping process, the existing concrete portion 12 on one side of the web portion 11c of the existing steel frame 11 is chipped to form a chipped portion 14. This makes it possible to easily form the chipped portion 14 in the existing concrete portion 12 in the chipping process, making it even easier to connect the steel beam 20 to the existing beam 10 of the existing building.

[0030] 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.

[0031] For example, in the above embodiment, the existing structure to which the steel beam 20 is connected is an existing beam 10 made of reinforced concrete and equipped with existing steel frame 11 formed from H-shaped steel, which constitutes the underground structure 2 of the existing building. However, the existing structure to which the steel beam 20 is connected may also be other existing structures of the existing building, such as existing columns that constitute the underground structure 2 of the existing building, or foundation beams that constitute the foundation structure of the existing building.

[0032] In addition, in this embodiment, in the chipping process, the existing concrete portion 12 on one side of the web portion 11c of the existing steel frame 11 is chipped to form a chipped portion 14, but the range of the existing concrete portion 12 chipped in the chipping process can be changed as appropriate depending on the size of the steel beam 20 to be connected, etc.

[0033] Furthermore, although this embodiment illustrates the case where a steel beam 20 is connected to an existing structure (existing beam 10) made of reinforced concrete, the present invention may also be applied to the case where a steel beam 20 is connected to an existing structure made of reinforced concrete that does not have steel built in. [Explanation of symbols]

[0034] 1. Building structure 2 Underground structure 10 Existing beam 11 Existing steel frame 11a Upper flange part 11b Lower flange part 11c Web section 12 Existing concrete section 13 Reinforced concrete 14 Chipboard 15 Newly constructed concrete section 16 Existing floor 17 Sub-cutting section 20 Steel beams 20a Upper flange part 20b Lower flange part 20c Web section 21 Connecting plate 22 Fastening members 23 PCB Plate 24 headed stud 25 New Beds 26 Headed stud

Claims

1. A method for connecting steel beams to an existing structure of reinforced concrete or reinforced steel concrete in an existing building, comprising: A chipping process of chipping a part of the existing concrete portion of the existing structure to form a chipped portion; a steel beam placement process for placing a newly installed steel beam having a headed stud fixed to its tip so that the headed stud is positioned in the notched portion; a new concrete portion pouring step of pouring a new concrete portion into the recessed portion and embedding the headed stud in the new concrete portion.

2. The existing structure is an existing beam made of reinforced concrete with an existing steel frame formed of H-shaped steel, 2. The method for connecting steel beams according to claim 1, wherein in the chipping step, the existing concrete portion on one side of the web portion of the existing steel frame is chipped to form the chipped portion.

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