JP7613937B2 - Back-to-back beam mounting structure - Google Patents

Description

The present invention relates to a back-to-back beam mounting structure.

A truss beam is known that includes a pair of upper string beams, a pair of lower string beams, and multiple shear-resistant braces (see, for example, Patent Document 1). The pair of upper string beams are arranged facing each other in the beam width direction, sandwiching a column. Similarly, the pair of lower string beams are arranged facing each other in the beam width direction, sandwiching a column. The shear-resistant brace connects the upper string beam and the lower string beam that face each other in the vertical direction.

In addition, a pair of back-to-back beams (double beams) are known that are arranged on both sides of a column facing each other in the beam width direction (see, for example, Patent Document 2).

JP 2017-503942 A Japanese Utility Model Application Publication No. 4-134303

By the way, it is possible to attach mounting components such as braces, dampers, and studs to a pair of back-to-back beams.

However, for example, if a mounting member such as a brace is attached to one of a pair of back-to-back beams, stress may be concentrated on one of the back-to-back beams during an earthquake, causing the back-to-back beam to deform.

Taking the above facts into consideration, the present invention aims to suppress deformation of a pair of back-to-back beams during an earthquake while attaching mounting members to the pair of back-to-back beams.

The back-to-back beam mounting structure of the first embodiment comprises a pair of back-to-back beams facing each other in the beam width direction across a column, a connecting member having a square tubular portion that is fitted between the web portions of the pair of back-to-back beams and connects the pair of back-to-back beams, and a mounting member that is attached to the connecting member.

According to the back-to-back beam mounting structure of the first aspect , a pair of back-to-back beams face each other in the beam width direction with a column in between. A square tube-shaped portion of a connecting member is fitted between the web portions of the pair of back-to-back beams. The pair of back-to-back beams are connected by the square tube-shaped portion. In addition, a mounting member is attached to the connecting member.

Here, in the present invention, as described above, the pair of back-to-back beams are reinforced by connecting the pair of back-to-back beams with a square tubular portion. This suppresses deformation of the pair of back-to-back beams when stress is concentrated on the pair of back-to-back beams from the mounting member during an earthquake.

The back-to-back beam mounting structure of the second aspect is the back-to-back beam mounting structure of the first aspect , in which the connecting member is provided on the square tube portion and has a gusset plate portion that is arranged along the beam core of a pair of the back-to-back beams in a planar view, and the mounting member is attached to the gusset plate portion.

According to the back-to-back beam mounting structure of the second aspect , the connecting member has a gusset plate portion. The gusset plate portion is provided on the rectangular tube portion of the connecting member and is disposed along the beam core of the pair of back-to-back beams in a plan view. The mounting member is attached to the gusset plate portion.

As a result, during an earthquake, a load is input from the mounting member through the gusset plate portion toward the beam core of the pair of back-to-back beams. As a result, eccentric bending that occurs in the pair of back-to-back beams during an earthquake is reduced. Therefore, deformation of the pair of back-to-back beams during an earthquake is further suppressed.

The back-to-back beam mounting structure of the third aspect is the back-to-back beam mounting structure of the first aspect , in which the connecting member has a horizontal flange portion extending laterally of the back-to-back beam from the lower end or upper end of the square tube portion, and the mounting member is attached to the horizontal flange portion.

According to the back-to-back beam mounting structure of the third aspect , the connecting member has a horizontal flange portion. The horizontal flange portion extends from the lower end or the upper end of the rectangular tube portion to the side of the back-to-back beam. The mounting member is attached to this horizontal flange portion.

By providing horizontal flanges on the connecting members in this way, it is possible to easily attach horizontal braces, etc. to the sides of a pair of back-to-back beams while suppressing deformation of the pair of back-to-back beams during an earthquake.

As described above, the back-to-back beam mounting structure of the present invention makes it possible to attach mounting members to a pair of back-to-back beams while suppressing deformation of the pair of back-to-back beams during an earthquake.

FIG. 1 is an elevation view showing a frame to which a back-to-back beam mounting structure according to a first embodiment is applied. FIG. 2 is a perspective view showing the connecting member shown in FIG. 1 . 3 is a side view of the connecting member shown in FIG. 2 as viewed from the beam width direction of the back-to-back beams. FIG. This is a cross-sectional view taken along line 4-4 of Figure 3. This is a cross-sectional view taken along line 5-5 in Figure 3. FIG. 11 is a plan view showing a frame to which a back-to-back beam mounting structure according to a second embodiment is applied. 7 is an enlarged plan view of a portion of FIG. 6 showing the connecting member shown in FIG. 6. This is a cross-sectional view taken along line 8-8 in Figure 7.

First Embodiment
First, the first embodiment will be described.

(Existing structure)
1 shows an existing structure 10 including a pair of back-to-back beams 20 to which the back-to-back beam mounting structure according to this embodiment is applied. The existing structure 10 is a steel frame structure. The existing structure 10 includes a pair of columns 12 and a pair of back-to-back beams 20 erected on the pair of columns 12. The existing structure 10 is an example of a structure.

The pair of columns (steel columns) 12 are formed, for example, from square steel pipes. The bases of the pair of columns 12 are supported by a foundation 14. The foundation 14 is, for example, a footing, and is buried in the ground G. A concrete floor 16 is laid on the ground G.

As shown in FIG. 2, the pair of back-to-back beams 20 are formed from C-shaped steel. Each back-to-back beam 20 has an upper flange portion 22 and a lower flange portion 24 that face each other in the vertical direction, and a web portion 26 that connects the upper flange portion 22 and the lower flange portion 24.

The pair of back-to-back beams 20 are arranged facing each other in the beam width direction (arrow W direction) with the column 12 (see FIG. 1) in between. The pair of back-to-back beams 20 are arranged with their respective web portions 26 facing inward (toward the column 12) and with the openings of the C-shaped steel facing outward. The pair of back-to-back beams 20 are joined to the column 12 by welding, bolts (not shown), or other joining means with the column 12 sandwiched between the respective web portions 26.

(Reinforcement structure for existing structure)
As shown in Fig. 1, an existing frame 10 is reinforced by a reinforcing stud 30 and a pair of reinforcing braces 50, 52. The reinforcing stud 30 and the reinforcing brace 52 are examples of mounting members.

(Reinforced studs)
2 and 3, the reinforcing stud 30 is formed of a C-shaped steel. This reinforcing stud 30 has a pair of flange portions 32 and a web portion 34 that connects the pair of flange portions 32. Note that the reinforcing stud 30 is not limited to a C-shaped steel, and may be formed of, for example, an H-shaped steel or a steel pipe.

As shown in FIG. 1, the reinforcing stud 30 is disposed between a pair of columns 12, and its base is supported by a foundation 36. The foundation 36 is, for example, a footing, and is buried in the ground G. The column head of the reinforcing stud 30 is attached to a pair of back-to-back beams 20 via a connecting member 60, which will be described later.

(Reinforcing brace)
The pair of reinforcing braces 50, 52 are provided on the structural surface of the frame 40 formed by one of the columns 12 (the column 12 on the left side in FIG. 1 ), the reinforcing stud 30, and the pair of back-to-back beams 20. The pair of reinforcing braces 50, 52 are, for example, X-shaped turnbuckle braces, and are arranged along diagonal corners of the frame 40.

The lower end of one of the reinforcing braces 50 is joined to the base of the reinforcing stud 30, and its upper end is joined to the head of one of the columns 12. The lower end of the other reinforcing brace 52 is joined to the base of one of the columns 12, and its upper end is joined to a pair of back-to-back beams 20 via a connecting member 60, which will be described later.

In addition, an opening 44 such as a passageway is formed in the frame 42 surrounded by the other pillar 12 (the pillar 12 on the right side in FIG. 1), the reinforcing stud 30, and the pair of back-to-back beams 20.

(Connecting member)
2 and 4, the connecting member 60 has a square tube portion 62, a horizontal flange portion 64, and a gusset plate portion 66. The square tube portion 62 is formed, for example, from a square steel pipe. The square tube portion 62 is fitted between the web portions 26 of the pair of back-to-back beams 20 with its axial direction being the beam formation direction (vertical direction) of the back-to-back beams 20.

As shown in FIG. 4, the height (axial length) of the square tube portion 62 is the same as the beam configuration of the pair of back-to-back beams 20. The upper end of the square tube portion 62 is disposed at the same height as the upper flange portion 22 of the pair of back-to-back beams 20. The lower end of the square tube portion 62 is disposed at the same height as the lower flange portion 24 of the pair of back-to-back beams 20.

The shape and size of the square tube portion 62 can be changed as appropriate. Therefore, for example, the upper end of the square tube portion 62 may protrude above the upper flange portion 22 of the pair of back-to-back beams 20.

As shown in FIG. 5, the cross-sectional shape of the square tube portion 62 is a rectangle with the material axis direction of the back-to-back beams 20 as the longitudinal direction. This square tube portion 62 has a pair of side wall portions 62A that face each other in the beam width direction of the back-to-back beams 20, and a pair of side wall portions 62B that face each other in the material axis direction of the back-to-back beams 20. The outer surfaces of the pair of side wall portions 62A are in contact (surface contact) with the inner surfaces of the web portions 26 of the pair of back-to-back beams 20, respectively.

A pair of side walls 62A of the square tube section 62 are formed with a plurality of through holes 62H that penetrate the side walls 62A in the thickness direction. In addition, a pair of back-to-back beams 20 have a web section 26 formed with a plurality of through holes 26H that penetrate the web section 26 in the thickness direction.

The multiple through holes 26H are connected to multiple through holes 62H formed in a pair of side wall portions 62A of the square tube portion 62. The web portions 26 and square tube portion 62 of the pair of back-to-back beams 20 are integrally connected by bolts 70 and nuts 72 inserted into these through holes 26H, 62H.

As shown in FIG. 4, a horizontal flange portion 64 is provided at the lower end of the square tube portion 62. The horizontal flange portion 64 is formed of a steel plate or the like that is rectangular in plan view, and is joined to the lower end of the square tube portion 62 by welding or the like.

The horizontal flanges 64 each extend laterally from the lower end of the square tube portion 62 and are superimposed on the lower surfaces of the lower flanges 24 of the pair of back-to-back beams 20. The horizontal flanges 64 are joined to the lower flanges 24 of the pair of back-to-back beams 20 by welding (fillet welding) or the like. The pair of back-to-back beams 20 is reinforced by the horizontal flanges 64.

As shown in FIG. 3, a gusset plate portion 66 is provided on the underside of the horizontal flange portion 64. The gusset plate portion 66 is formed of a rectangular steel plate or the like when viewed from the beam width direction of the back-to-back beams 20. Also, as shown in FIG. 5, the gusset plate portion 66 is arranged with its thickness direction being the beam width direction of the back-to-back beams 20. This gusset plate portion 66 is arranged along the beam core 20C of the pair of back-to-back beams 20 in a plan view.

As shown in FIG. 4, the gusset plate portion 66 has a plurality of through holes 66H formed therein. The plurality of through holes 66H penetrate the gusset plate portion 66 in the thickness direction. The plurality of through holes 66H are also arranged at intervals in the vertical direction. The web portion 34 of the column head of the reinforcing stud 30 is placed over the gusset plate portion 66.

The web portion 34 of the column head of the reinforcing stud 30 has a plurality of through holes 34H formed therein. The plurality of through holes 34H penetrate the web portion 34 in the thickness direction. The plurality of through holes 34H also communicate with a plurality of through holes 66H formed in the gusset plate portion 66. The gusset plate portion 66 and the column head of the reinforcing stud 30 are joined together by bolts 38 and nuts 39 inserted into the through holes 34H, 66H.

As shown in FIG. 2, a bracket 54 provided at the upper end of the reinforcing brace 52 is placed on the gusset plate portion 66. The bracket 54 and the gusset plate portion 66 each have a through hole (not shown). The bracket 54 and the gusset plate portion 66 are joined together by a bolt 56 and a nut 58 inserted into the through hole. The bracket 54 may be, for example, a shuttlecock plate.

(Action)
Next, the operation of the first embodiment will be described.

As shown in FIG. 2, in the back-to-back beam mounting structure of this embodiment, the square tube portion 62 of the connecting member 60 is fitted between the web portions 26 of the pair of back-to-back beams 20. This square tube portion 62 and the web portions 26 of the pair of back-to-back beams 20 are connected together by a number of bolts 70 and nuts 72.

In this way, by connecting the web portions 26 of the pair of back-to-back beams 20 via the square tube portions 62, the joints (attachment portions) between the reinforcing studs 30 and the reinforcing braces 52 in the pair of back-to-back beams 20 are reinforced. This suppresses deformation of the pair of back-to-back beams 20 when stress is concentrated on the pair of back-to-back beams 20 from the reinforcing studs 30 and the reinforcing braces 52 during an earthquake.

The reinforcing studs 30 and reinforcing braces 52 are joined to the gusset plate portions 66 of the connecting members 60. The gusset plate portions 66 are arranged along the beam cores 20C (see FIG. 5) of the pair of back-to-back beams 20 in a plan view.

During an earthquake, the load of the reinforcing studs 30 and the reinforcing braces 52 is input toward the beam cores 20C of the pair of back-to-back beams 20 via the gusset plate portions 66. As a result, eccentric bending that occurs in the pair of back-to-back beams 20 during an earthquake is reduced. Therefore, deformation of the pair of back-to-back beams 20 during an earthquake is further suppressed.

Furthermore, as shown in FIG. 4, the connecting member 60 is provided with a horizontal flange portion 64. This horizontal flange portion 64 is disposed along the underside of the lower flange portions 24 of the pair of back-to-back beams 20, and is joined to these lower flange portions 24 by welding or the like. This horizontal flange portion 64 reinforces the joints between the reinforcing studs 30 and the reinforcing braces 52 of the pair of back-to-back beams 20, thereby further suppressing deformation of the pair of back-to-back beams 20 during an earthquake.

In addition, as shown in FIG. 1, in this embodiment, by providing a reinforcing stud 30 to the existing frame 10, the existing frame 10 can be reinforced by a pair of reinforcing braces 50, 52 while an opening 44 for a passage or the like can be secured on one side of the reinforcing stud 30.

Second Embodiment
Next, a second embodiment will be described. In the second embodiment, the same reference numerals will be used to designate the same members as in the first embodiment, and the description thereof will be omitted as appropriate.

(Existing structure)
6 shows an existing structure 80 having a pair of back-to-back beams 20 to which the back-to-back beam mounting structure according to the second embodiment is applied. The existing structure 80 is a flat frame made of steel. The existing structure 80 has two pairs of back-to-back beams 20 and two pairs of back-to-back beams 82.

Columns 12 are arranged at each corner of the existing frame 80. As shown in FIG. 7, a pair of back-to-back beams 20 and a pair of back-to-back beams 82 are arranged around each column 12 in a grid pattern (a lattice pattern) in plan view. These back-to-back beams 20 are joined to the columns 12 by joining means such as welding or bolts (not shown).

(Reinforcement structure for existing structure)
6, the existing frame 80 is reinforced by a pair of reinforcing horizontal braces 90. The pair of reinforcing horizontal braces 90 is, for example, an X-shaped turnbuckle brace, and is disposed along diagonal corners of the existing frame 80.

As shown in FIG. 7, one end of each reinforcing horizontal brace 90 is attached to one end of a pair of back-to-back beams 20 via a connecting member 100, and the other end is attached to the other end of the pair of back-to-back beams 20 via a connecting member 100. The reinforcing horizontal brace 90 is an example of an attachment member.

(Connecting member)
As shown in Fig. 8, the connecting member 100 has a rectangular tube portion 102 and a horizontal flange portion 104. The rectangular tube portion 102 is formed, for example, from a rectangular steel pipe. The rectangular tube portion 102 is fitted between the web portions 26 of the pair of back-to-back beams 20 with its axial direction being the material axis direction of the back-to-back beams 20.

The rectangular tube portion 102 has a pair of side walls 102A that face each other in the beam width direction of the back-to-back beams 20, and a pair of side walls 102B that face each other in the beam configuration direction (up-down direction) of the back-to-back beams 20. The outer surfaces of the pair of side walls 102A are in contact (surface contact) with the inner surfaces of the web portions 26 of the pair of back-to-back beams 20.

A pair of side walls 102A of the square tube portion 102 are formed with a plurality of through holes 102H that penetrate the side walls 102A in the thickness direction. The plurality of through holes 102H are connected to a plurality of through holes 26H formed in the web portions 26 of the pair of back-to-back beams 20. The web portions 26 of the pair of back-to-back beams 20 and the square tube portion 102 are integrally connected by bolts 110 and nuts 112 inserted into these through holes 26H, 102H.

The horizontal flange portion 104 is provided at the lower end of the rectangular tube portion 102. This horizontal flange portion 104 is formed from a steel plate or the like that is rectangular in plan view, and is joined to the lower end of the rectangular tube portion 102 by welding or the like.

The horizontal flanges 104 each extend laterally from the lower end of the square tube portion 102 and are superimposed on the lower surfaces of the lower flanges 24 of the pair of back-to-back beams 20. The horizontal flanges 104 are joined to the lower flanges 24 of the pair of back-to-back beams 20 by welding (fillet welding) or the like. The pair of back-to-back beams 20 is reinforced by the horizontal flanges 104.

The horizontal flange portion 104 passes under one of the back-to-back beams 20 and extends to the side of the back-to-back beams 20. A bracket 92 provided at one end of the reinforcing horizontal brace 90 is placed on this horizontal flange portion 104. In addition, the horizontal flange portion 104 and the bracket 92 each have a through hole (not shown). One end of the reinforcing horizontal brace 90 is attached to the pair of back-to-back beams 20 by a bolt 94 and a nut 96 inserted into these through holes.

As shown in FIG. 7, the reinforcing horizontal brace 90 is positioned so that the extension line of its brace core 90C passes through the target point P set on the column 12 in a plan view. This allows the stress of the reinforcing horizontal brace 90 to be efficiently transmitted to the column 12 via the connecting member 100 and the pair of back-to-back beams 20 during an earthquake.

In this embodiment, the target point P is set on the side of the pillar 12. However, the location of the target point P can be changed as appropriate, and for example, it may be set at the center (material axis) of the pillar 12 in a plan view.

(Action)
Next, the operation of the second embodiment will be described.

As shown in FIG. 8, in the back-to-back beam mounting structure of this embodiment, the connecting member 100 has a horizontal flange portion 104. The horizontal flange portion 104 passes from the lower end of the square tube portion 102 to the underside of the back-to-back beams 20 on both sides and extends out to the sides of these back-to-back beams 20. One end of the reinforcing horizontal brace 90 is attached to the extending portion of the horizontal flange portion 104.

By providing the horizontal flange portion 104 on the connecting member 100 in this manner, it is possible to easily attach the reinforcing horizontal brace 90 to the side of the pair of back-to-back beams 20 while suppressing deformation of the pair of back-to-back beams 20 during an earthquake.

Also, as shown in FIG. 7, the mounting angle of the reinforcing horizontal brace 90 relative to the pair of back-to-back beams 20 can be easily adjusted by changing the shape and size of the horizontal flange portion 104. This allows the reinforcing horizontal brace 90 to be mounted to the pair of back-to-back beams 20 so that the brace core 90C of the reinforcing horizontal brace 90 passes through the target point P of the column 12 in a plan view.

In this embodiment, the horizontal flange portion 104 is provided at the lower end of the rectangular tube portion 102. However, the horizontal flange portion 104 may be provided at the upper end of the rectangular tube portion 102.

(Modification)
Next, modified examples of the first and second embodiments will be described. Note that, although various modified examples will be described below using the first embodiment as an example, these modified examples can also be appropriately applied to the second embodiment.

In the first embodiment described above, the gusset plate portion 66 of the connecting member 60 is arranged along the beam core 20C of the pair of back-to-back beams 20 in a plan view. However, the gusset plate portion 66 may be arranged, for example, at a position that is offset from the beam core 20C of the pair of back-to-back beams 20 in a plan view.

In the first embodiment, the reinforcing stud 30 and the reinforcing brace 52 are attached to the gusset plate portion 66 of the connecting member 60. However, the reinforcing stud 30 and the reinforcing brace 52 are not limited to the gusset plate portion 66, and may be attached to, for example, a steel frame member provided at the lower end of the square tube portion 62, or may be attached to the horizontal flange portion 64. Furthermore, for example, the horizontal flange portion 64 and the gusset plate portion 66 may be omitted from the connecting member 60, and the reinforcing stud 30 and the reinforcing brace 52 may be attached to the square tube portion 62.

In the first embodiment, the reinforcing brace 52 serving as the mounting member is a turnbuckle brace. However, the reinforcing brace serving as the mounting member is not limited to a turnbuckle brace, and may be, for example, a steel brace.

In addition, in the first embodiment, the mounting members are the reinforcing studs 30 and the reinforcing braces 52. However, the mounting members are not limited to the reinforcing studs 30 and the reinforcing braces 52, and may be, for example, dampers, etc.

In the first embodiment, the square tube portion 62 of the connecting member 60 is arranged so that its axial direction is the beam height direction (vertical direction) of the back-to-back beams 20. However, the installation direction of the square tube portion 62 of the connecting member 60 can be changed as appropriate depending on the situation. For example, if the beam height of the back-to-back beams 20 is low, the axial direction of the square tube portion 62 may be arranged so that it is the material axis direction of the back-to-back beams 20.

In the first embodiment, the pair of back-to-back beams 20 are formed from C-shaped steel. However, the pair of back-to-back beams 20 is not limited to C-shaped steel, and may be formed from, for example, square steel pipes. The pair of back-to-back beams 20 is not limited to steel construction (steel beams), and may be formed from, for example, wood construction (wood beams).

In addition, in the first embodiment, the existing frame 10 is provided on the first floor of the structure and is supported by the foundation 14. However, the existing frame 10 may be provided on the second or higher floor of the structure.

Furthermore, in the above first embodiment, the pair of back-to-back beams 20 are existing, but the pair of back-to-back beams 20 may be newly constructed. Also, in the above first embodiment, the frame is an existing frame 10, but the frame may be a newly constructed frame.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and the embodiments and various modifications may be used in appropriate combinations, and the present invention may of course be embodied in various forms without departing from the spirit of the present invention.

12 Column 20 Pair of back-to-back beams 20C Beam core (beam core of a pair of back-to-back beams)
26 Web portion (web portion of back-to-back beam)
30 Reinforcement stud (mounting member)
52 Reinforcement brace (mounting member)
60 Connecting member 62 Square cylindrical portion (square cylindrical portion of connecting member)
66 Gusset plate portion 90 Reinforcing horizontal brace (mounting member)
100 Connecting member 102 Square cylindrical portion (square cylindrical portion of connecting member)
104 Horizontal flange portion (horizontal flange portion of connecting member)
W: Beam width direction of a pair of back-to-back beams

Claims (3)

A pair of back-to-back beams facing each other in the beam width direction with a column in between;
A connecting member having a square tubular portion that is fitted between the web portions of the pair of back-to -back beams and is bolted to the web portions to connect the pair of back-to-back beams;
An attachment member attached to the connecting member;
A back-to-back beam mounting structure. A pair of back-to-back beams facing each other in the beam width direction with a column in between;
A connecting member having a square tube-shaped portion that is fitted between the web portions of the pair of back-to-back beams and connects the pair of back-to-back beams;
An attachment member attached to the connecting member;
Equipped with
The connecting member is provided on the square tube portion and has a gusset plate portion arranged along the beam core of the pair of back-to-back beams in a plan view,
The mounting member is attached to the gusset plate portion.
Back- to-back beam mounting structure. A pair of back-to-back beams facing each other in the beam width direction with a column in between;
A connecting member having a square tube-shaped portion that is fitted between the web portions of the pair of back-to-back beams and connects the pair of back-to-back beams;
An attachment member attached to the connecting member;
Equipped with
The connecting member has a horizontal flange portion extending from a lower end or an upper end of the square tube portion to a side of the back-to-back beam,
The mounting member is attached to the lateral flange portion.
Back- to-back beam mounting structure.