JP7702913B2 - Reinforcing plate and reinforcing plate joint structure - Google Patents

Description

This disclosure relates to a reinforcing plate and a reinforcing plate joint structure.

In steel-framed buildings, in order to transmit the bending moment from the beam to the column, a reinforcing plate called an internal diaphragm, which is one or two ranks thicker than the plate thickness of the beam flange, is often provided in the column-beam joint structure. In particular, when multiple beams 4, 5 connected to a steel pipe column 1 have different beam depths, as shown in Figure 1, a reinforcing plate called a through diaphragm 6 is connected to the placement height of the beam flange 4a of the beam 4 with a larger beam depth, and an internal diaphragm 2 is connected to the inside of the steel pipe column 1 at the placement height of one of the beam flanges 5a of the beam 5 with a smaller beam depth. In this case, the two through diaphragms 6 are connected to both ends of a short steel pipe (sometimes called a "dice") 3, and the internal diaphragm 2 is placed inside the die 3.

Patent Document 1 discloses a stepped beam-column joint structure having a through diaphragm and an inner diaphragm, characterized in that the inner diaphragm welded into the steel pipe is offset from the position of the beam flange with a lower beam depth that is joined to the beam-column joint structure. This allows a wide distance to be secured between the backing metal of the welded portion of the through diaphragm and the backing metal of the welded portion of the inner diaphragm, preventing interference between the backing metals.

JP 2017-66599 A

In such a structure having an inner diaphragm 2, after the inner diaphragm 2 is placed inside the die 3 as shown in FIG. 2, the outer periphery of the inner diaphragm 2 and the inner surface of the die 3 are welded together.
In order to place the inner diaphragm 2 inside the die 3, it is necessary to process the outer periphery of the inner diaphragm 2 to be smaller than the inner periphery of the die 3. When welding the die 3 and the inner diaphragm 2 by full penetration welding of a square groove, a gap (= root gap) of about 7 mm to 9 mm is generally provided between the end face of the inner diaphragm 3 and the inner surface of the die, so that, as shown in Figure 3, if the inner diameter of the opening of the die 3 is d (mm), the width of the inner diaphragm 2 is processed to be about d-18 (mm) or more and d-14 (mm) or less.

Here, cold-formed rectangular steel pipes are often used for the die 3, but not only cold-formed rectangular steel pipes, but also rectangular steel pipes are not completely straight in the steel pipe axial direction, and as shown in Figure 4, there are cases where a dent occurs on the inside of the steel pipe cross section. According to the literature (Japan Construction Center, Cold-Formed Square Steel Pipe Design and Construction Manual, 1st Edition, February 2018), the dent in the flat part of the rectangular steel pipe is controlled to be 0.5% or less of the steel pipe diameter (mm) and 3.0 mm or less. In other words, the inner diameter d (mm) of the die 3 at the mounting height position of the inner diaphragm 2 may be up to 6 mm smaller than the inner diameter of the opening of the die 3. Even in this case, as described above, the width of the inner diaphragm 2 is processed to be about 14 mm to 18 mm smaller than the inner diameter of the opening of the die 3, so even if the inside of the die 3 is the most concave within the specified range, the inner diaphragm 2 can be placed horizontally inside the die 3. Therefore, when the inner diaphragm 2 is joined to the inside of the die 3 by full penetration welding, it is relatively easy to position the inner diaphragm 2 on the inside of the die 3.

On the other hand, full penetration welding requires backing metal, which can be time-consuming to perform, so when welding the inner diaphragm to the inside of the square steel pipe, it is sometimes desirable to join the inner diaphragm by partial penetration welding or full penetration welding of a K-shaped groove. In this case, unlike the full penetration welding of the R-shaped groove described above, it has the advantage of not requiring a backing metal, but it is necessary to keep the gap between the inner diaphragm and the inner surface of the die (= root gap) to 3 mm or less (Architectural Institute of Japan: Standard Specifications for Building Construction JASS6 Steel Construction 11th Edition, January 2018).

In this case, if the inner diameter of the opening of the die 3 is d (mm), the width of the inner diaphragm 2 needs to be processed to be d-6 (mm) or more and d (mm) or less. Here, as mentioned above, the inner surface of the die 3 is not completely straight in the axial direction of the steel pipe, and the inner diameter of the die 3 at the mounting height of the inner diaphragm 2 may be up to 6 mm smaller than the inner diameter of the opening. This means that the inner diameter of the die 3 may be smaller than the width of the inner diaphragm 2. In such a case, the inner diaphragm 2 gets caught inside the die 3 and tilts significantly. In this case, it is necessary to take the inner diaphragm 2 out of the die 3, adjust the width of the inner diaphragm 2, and then put it back inside the die 3. Therefore, when the inner diaphragm 2 is joined by partial penetration welding or full penetration welding of a K-shaped groove, there is a problem that it is very difficult to place the inner diaphragm inside the die.

The present disclosure therefore aims to provide a reinforcing plate that can be properly welded even when the inner diameter of the steel pipe at the location where the reinforcing plate is to be placed is smaller than the width of the reinforcing plate. It also provides a structure that uses this reinforcing plate.

This application discloses a reinforcing plate that is inserted into a square steel pipe with a rectangular cross section and has four sides whose outer edges are welded to the inner surface of the square steel pipe, and at least two of the four sides of the reinforcing plate that are opposite each other have a R-shaped groove with an opening on one of the plate surfaces, and the R-shaped grooves that are located on the opposite sides of the pair of two sides have openings on the plate surfaces that are opposite each other.

The present application also discloses a reinforcing plate joint structure comprising a square steel pipe having a rectangular cross-sectional shape, the reinforcing plate arranged inside the square steel pipe, and a weld provided in the V-shaped groove to join the inner surface of the square steel pipe and the reinforcing plate.

The present application also discloses a reinforcing plate that is inserted into a square steel pipe with a rectangular cross-sectional shape, with its outer peripheral end welded to the inner surface of the square steel pipe, and at least two of the four sides of the reinforcing plate that are opposite each other have openings on both plate surface sides, and a K-shaped groove is provided in which one opening is wider than the other opening, and in the K-shaped grooves located on the opposite sides of the pair of sides, the opening with the larger width is provided on the plate surface side opposite each other.

The present application also discloses a reinforcing plate joint structure comprising a square steel pipe having a rectangular cross-sectional shape, the reinforcing plate arranged inside the square steel pipe, and a weld provided in the K-shaped groove to join the inner surface of the square steel pipe and the reinforcing plate.

According to the present disclosure, proper welding can be performed even if the inner diameter of the steel pipe at the location where the reinforcing plate is placed is smaller than the width of the reinforcing plate.

FIG. 1 is a diagram illustrating the structure of a beam-column joint structure equipped with an internal diaphragm. FIG. 2 is a diagram illustrating a situation in which the inner diaphragm is placed on the die. FIG. 3 is a diagram for explaining the relationship between the die opening and the width of the inner diaphragm when welding is performed by full penetration welding of a R-shaped groove. FIG. 4 is a diagram illustrating the depressions on the inner surface of the die. FIG. 5 is an external perspective view of the reinforced plate joint structure 10. As shown in FIG. FIG. 6 is a cross-sectional view of the reinforced plate joint structure 10. FIG. 7 is a plan view of the inner diaphragm 12. As shown in FIG. FIG. 8 is a cross-sectional view of the inner diaphragm 12. FIG. 9 is a cross-sectional view of the inner diaphragm 12. FIG. 10 is a cross-sectional view of the inner diaphragm 20. As shown in FIG. FIG. 11 is a cross-sectional view illustrating the inclination of a conventional inner diaphragm. FIG. 12 is a cross-sectional view illustrating the inclination of the inner diaphragm in the present disclosure. FIG. 13 is a diagram illustrating the embodiment of Comparative Example 1. FIG. 14 is a diagram illustrating the configuration of Comparative Example 2. FIG. 15 is a diagram for explaining the configuration of the first embodiment. FIG. 16 shows the results of Case 1. FIG. 17 shows the results of Case 2. FIG. 18 shows the results of Case 3. FIG. 19 shows the results of Case 4.

5 and 6 are perspective views each showing a schematic external view of a joint structure 10 according to one embodiment of the present invention. Fig. 6 is a cross-sectional view of the joint structure 10 in the direction along the tube axis of the die 11.

As can be seen from Figures 5 and 6, the reinforced plate joint structure 10 is composed of a die 11, which is a square steel tube, and an inner diaphragm 12, which is a reinforcing plate. In this embodiment, the reinforced plate joint structure 10 has a partial penetration weld 13. That is, in the reinforced plate joint structure 10, the inner diaphragm 12, which is a reinforcing plate, is placed inside the die 11, and the inner surface of the die 11 and the outer peripheral end of the inner diaphragm 12 are joined by partial penetration welding. The fact that it is a partial penetration weld can be recognized by the fact that no backing metal is provided.

1.1.1 Dice Dice 11 is one form of square steel pipe having a rectangular cross-sectional shape, as is well known. As explained with reference to Fig. 4 above, the square steel pipe of this embodiment, including die 11, is allowed to have an inward depression so that its inner diameter becomes smaller. However, the allowable range is 0.5% or less of the steel pipe diameter (mm) and 3.0 mm or less, as described above.

1.1.2. Inner diaphragm The inner diaphragm 12 is a plate-like member with four sides that functions as a reinforcing plate placed inside the die 11, and has two plate surfaces (surfaces perpendicular to the plate thickness direction) 12a that form the front and back. Figures 7 and 8 are shown for explanatory purposes. Figure 7 is a plan view of the inner diaphragm 12, and Figure 8 is a cross-sectional view taken along the line A-A in Figure 7. As can be seen from Figure 7, notches 12b are provided at the four corners in plan view. This eliminates problems with the placement of the inner diaphragm 12 due to interference with the recessed corners on the inner surface of the die 11.

As described above, the inner diaphragm 12 is joined to the inside of the die 11 by partial penetration welding, and therefore has grooves 12c for partial penetration welding on all four sides. Fig. 9 shows an enlarged view of the grooves 12c.
As can be seen from Fig. 9, this embodiment has a V-shaped groove. That is, the groove 12c is provided only on one plate surface 12a side of the inner diaphragm 12, and an opening 12d is provided on the one plate surface 12a side.
The shape of the groove is not particularly limited, and the groove angle is also known. The length f of the root face is also not particularly limited, and the length f of the root face may be 0 (mm).

In this embodiment of the inner diaphragm 12, the grooves 12c on the opposite sides of the four sides are configured so that the plate surfaces 12a on which the openings 12d are located are opposite each other. This allows proper welding even if the inner diameter of the die 11 is smaller than the width of the inner diaphragm 12 at the location where the inner diaphragm 12 is located. The reason for this will be explained later.

1.2. Full penetration welding The inner diaphragm of the present disclosure can also be used for a groove that does not require a backing metal among full penetration welding. An explanatory diagram is shown in Fig. 10. Fig. 10 is a diagram from the same viewpoint as Fig. 9, and is a diagram for explaining the form of the inner diaphragm 20 that functions as a reinforcing plate. The inner diaphragm 20 can be considered to be the same as the inner diaphragm 12 except for the shape of the groove, so the shape of the groove will be described here.

As can be seen from Fig. 10, this embodiment has a K-shaped groove. That is, a groove 20a is provided on one plate surface 12a side, and a groove 20b is provided on the other plate surface 12a side. In this embodiment, the groove 20a has an opening 20ab on the plate surface 12a side, and the groove 20b has an opening bb on the plate surface 12a side, and the width L1 of the opening 20ab is configured to be larger than the width L2 of the opening 20bb.
The groove angle and the length of the root face are not particularly limited and may be set to a required value. The length f of the root face may be 0 (mm).

In this embodiment of the inner diaphragm 20, the grooves on the opposite sides of the four sides are configured so that the plate surface 12a on which the opening 20ab is located is opposite, and the plate surface 12a on which the opening 20bb is located is opposite. This allows proper welding even if the inner diameter of the die 11 at the location where the inner diaphragm 20 is located is smaller than the width of the inner diaphragm 20. The reason for this will be explained later.

2. Effects, etc. As shown in FIG. 11, if an inner diaphragm having a conventional groove shape and a width larger than the inner diameter of the narrowed die is placed on a die with a smaller inner diameter at the position where the inner diaphragm is placed, the inner diaphragm will be inclined at an angle of θ. Even if the inclination θ is very small, it is said that there is no problem in construction. For example, in the literature (Architectural Institute of Japan, Standard Specifications for Construction Work JASS6 Steel Construction 11th Edition, 2018.1), the allowable angle for the welded joint of a R-shaped groove is 2.5° (the limit allowable angle is 5°). In other words, even if the inner diameter of the die at the position where the inner diaphragm is placed is smaller than the width of the inner diaphragm and it is inclined as shown in FIG. 11, the inner diaphragm can be welded and joined as it is as long as the inclination is within the angle allowable in construction management. However, it is preferable that this angle is as small as possible.

As shown in FIG. 11, when both grooves are provided on one surface of the inner diaphragm, θ inevitably becomes large.
On the other hand, according to the above-mentioned inner diaphragm 12 as shown in Figure 12, the two grooves 12c arranged on the opposite side have openings 12d provided on the opposite plate surface 12a, so that even if the inner diaphragm has the same width, the inclination θ of the inner diaphragm 12 when the inner diaphragm 12 comes into contact with the inner surface of the die 11 inside the die 11 can be made smaller than before.

Therefore, it is possible to increase the number of situations where proper welding can be performed even if the inner diameter of the die 11 (square steel pipe) is smaller than the width of the inner diaphragm 12 at the location where the inner diaphragm 12 (reinforcement plate) is disposed. The same applies to the inner diaphragm 20.
In addition, since it is easy to position the inner diaphragm 12 inside the die 11, welding methods that do not require backing metal, such as partial penetration welding and full penetration welding of a K-shaped groove, can be easily applied to joining the inner diaphragm.

3. Examples In order to demonstrate the usefulness of the inner diaphragm (reinforcing plate) of the present disclosure, a comparative study was conducted by numerical calculation for inner diaphragms having three types of cross-sectional shapes shown in Figures 13 to 15. Comparative Example 1 shown in Figure 13 is an example of an inner diaphragm without a groove, and Comparative Example 2 shown in Figure 14 is an inner diaphragm with a conventional R-shaped groove and an opening on the same plate surface side. And the example shown in Figure 15 is an inner diaphragm imitating the example of inner diaphragm 12 in the case of having a R-shaped groove shown in Figure 8. Here, as shown in Figures 13 to 15, if the width of the inner diaphragm is _Bd (mm), the plate thickness of the inner diaphragm is _td (mm), the inner diameter of the die is D (mm), the groove angle of the inner diaphragm is α (°), the size of the root face of the groove of the inner diaphragm is f (mm), the inclination of the inner diaphragm is θ (°) (where θ≦α), and the gap between the inner surface of the die and the inner diaphragm is x (mm), the gap x in each example can be geometrically determined and is obtained from equation (1) for Comparative Example 1, equation (2) for Comparative Example 2, and equation (3) for Example 1.
x=D−B _d・cosθ−t _d・sinθ…(1)
x=D-B _d・cosθ−f・sinθ…(2)
x=D−B _d・cosθ+(t _d −2・f)・sinθ…(3)

Assuming that the inner diameter D of the die is smaller than the width _Bd of the inner diaphragm, and assuming that D = _Bd -1 (mm), from equations (1) to (3), the gap x in each example can be expressed by equations (4) to (6), respectively.
x=B _d・(1−cosθ)−t _d・sinθ−1…(4)
x=B _d・(1−cosθ)−f・sinθ−1…(5)
x=B _d・(1−cosθ)+(t _d −2・f)・sinθ−1…(6)

Using the above formulas (4) to (6), we performed numerical calculations for the four cases shown in Table 1.

The results showing the relationship between x and θ are shown in Figures 16 to 19. Figure 16 shows case 1, Figure 17 shows case 2, Figure 18 shows case 3, and Figure 19 shows case 4. The size f of the root face in each case was set to 2 mm. In Figures 16 to 19, the horizontal axis shows the inclination θ of the inner diaphragm, and the vertical axis shows the gap x between the inner diaphragm and the die. If the gap x is 0 or less, they are in contact. Also, the circle in each figure shows the inclination θ of the inner diaphragm when the gap x in each example is 0, and the black dashed line shows the allowable angle (2.5°) shown in the above literature. In other words, if the circle is located to the left of the dashed line in each graph, it means that the construction conditions for the inner diaphragm are met. As can be seen from Figures 16 to 19, only Example 1 satisfies the conditions in all cases.

10 Reinforced plate joint structure 11 Square steel pipe column (dice)
12, 20 Reinforcing plate (inner diaphragm)
13 Welded parts

Claims (4)

A plate-shaped reinforcing plate having four sides is inserted into a square steel pipe having a rectangular cross-sectional shape, and its outer peripheral end is welded to the inner surface of the square steel pipe,
At least a pair of two sides of the reinforcing plate that are opposite to each other among the four sides are provided with a V-shaped groove having an opening on one of the plate surfaces,
In the L-shaped grooves arranged on the opposite sides of the pair of sides, the openings are provided on the plate surface sides opposite to each other,
Reinforcement plate. Square steel pipes having a rectangular cross-sectional shape,
The reinforcing plate according to claim 1, which is disposed inside the square steel pipe; and
A weld portion provided in the groove so as to join the inner surface of the square steel pipe and the reinforcing plate,
Reinforcement plate joint structure. A plate-shaped reinforcing plate having four sides is inserted into a square steel pipe having a rectangular cross-sectional shape, and its outer peripheral end is welded to the inner surface of the square steel pipe,
At least a pair of two sides of the reinforcing plate that are opposite to each other among the four sides have openings on both plate surface sides, and a K-shaped groove is provided in which the width of one of the openings is larger than the width of the other opening,
In the K-shaped grooves arranged on the opposite sides of the pair of sides, the openings having the larger width are provided on the plate surface sides opposite to each other,
Reinforcement plate. Square steel pipes having a rectangular cross-sectional shape,
The reinforcing plate according to claim 3, which is disposed inside the square steel pipe; and
A weld portion provided in the K-shaped groove so as to join the inner surface of the square steel pipe and the reinforcing plate,
Reinforcement plate joint structure.

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