JP7033866B2 - Fitting structure - Google Patents

Description

The present invention relates to a joint structure of a square steel pipe.

The steel pipe column is formed to a predetermined length (height) by connecting the steel pipes vertically.
As a method of connecting steel pipes to each other, a method of welding with the end faces of the steel pipes butted against each other may be adopted. Welded joints may be hindered by the weather. In addition, since sparks are generated during work in welded joints, it is necessary to give due consideration to fire safety. Further, in the welded joint, if the joint portion deteriorates over time, it is necessary to install a reinforcing member, and the repair work is troublesome.
Therefore, as a method of connecting steel pipes to each other, a joint structure is disclosed in which a joint plate is attached to a joint portion between steel pipes and the joint plate is fastened with a high-strength bolt. When fastening high-strength bolts, it is necessary to work from both the inside and outside of the steel pipe.
Therefore, in Patent Document 1, notches are provided at the tip corners of both steel pipes so that a work opening into which a worker's arm can be inserted is formed when the steel pipes are butted against each other. A joint structure is disclosed in which a joint plate attached between the left and right work openings is fastened with a high-strength bolt by using the opening.
Further, in Patent Document 2, a working opening (groove) formed in the center of the end of one of the steel pipes is used, and joint plates attached to the left and right sides of the working opening are provided with high-strength bolts. The joint structure to be fastened is disclosed.

Japanese Unexamined Patent Publication No. 2004-293196 Japanese Unexamined Patent Publication No. 2002-129658

In the joint structure of Patent Document 1, since high-strength bolts are concentrated in the central portion of the side surface of the steel pipe, the stress at the corner portion can be transmitted only in the central portion. Therefore, the rigidity and the proof stress may decrease. In addition, since a working opening is formed by notching the corners that are being plastically worked, it is necessary to carefully process the steel pipes so that the corners are not cracked or otherwise damaged.
In the joint structure of Patent Document 2, since the joint plate is divided into the left and right of the working opening, there is a possibility that the shear strength and rigidity in the joint portion will be insufficient. Further, in order to arrange the required number of bolts, it is necessary to lengthen the joint plate, which may be uneconomical due to an increase in the amount of steel material.
From this point of view, it is an object of the present invention to propose an economical joint structure having necessary rigidity and proof stress.

In order to solve the above problems, the present invention has a joint structure for joining a pair of square steel pipes having end faces butted against each other, and a joint plate attached across the pair of square steel pipes, the joint plate and the above. It is provided with a plurality of bolts for fastening the square steel pipes, and a recess is formed in the center of each end of each square steel pipe so that a working opening is formed when the square steel pipes are joined to each other. A through hole having the same shape as the working opening is formed in the central portion of the joint plate, and the bolts are arranged vertically in addition to the left and right of the working opening. It is a feature.
According to such a joint structure, since the through hole is formed in the central portion of the joint plate corresponding to the position of the work opening, it is not necessary to divide the joint plate so as to avoid the work opening. Therefore, the required rigidity and proof stress can be ensured. In addition, since it is not necessary to divide the joint plate, the degree of freedom in bolt arrangement is increased. Therefore, the shape of the joint plate can be suppressed to the minimum necessary area, and an economical joint structure can be formed. It is desirable that the pair of square steel pipes and the joint plate are formed with bolt holes through which the bolts are inserted, not only on the left and right sides of the work opening but also on the upper and lower sides. In this way, the stress can be evenly dispersed and transmitted. The joint structure is particularly suitable for thin square steel pipes in which it is difficult to weld the joint plate from the inside. According to the joint structure, more high-strength bolts can be arranged than in the case of fixing the divided plate divided into two to the thin square steel pipe. In addition, with a square steel pipe whose inner width is narrower than the length of the worker's arm, it is possible to put a hand through one work opening and fasten the nut to each side, so the work opening is formed on only one side. That's enough. When the working opening is formed on only one surface, it is possible to save the trouble of forming the opening in the square steel pipe and the joint plate with respect to the other three surfaces, and the joint strength is advantageous because the cross-sectional defect is reduced.

According to the joint structure of the present invention, it has necessary rigidity and proof stress, and it is possible to economically connect square steel pipes.

It is a figure which shows the joint structure which concerns on embodiment of this invention, (a) is a front view, (b) is a sectional view of (a). It is a perspective view which shows the end part of a square steel pipe. It is a perspective view which shows the joint plate. It is a figure which shows the shape dimension of the joint plate used for analysis, and (a)-(c) are Example, Comparative Example 1 and Comparative Example 2, respectively. It is a graph which shows the result of the analysis performed about the joint structure using the joint plate of FIGS. 4A to 4C. (A) to (c) are deformation / stress contour diagrams showing the results of analysis performed on the joint structure using the joint plates of FIGS. 4 (a) to 4 (c).

Hereinafter, the joint structure 1 of the steel pipe column 2 will be described.
The steel pipe column 2 of the present embodiment is formed by connecting a plurality of square steel pipes 21 and 21 in the vertical direction via a joint structure 1, and is formed to have a predetermined length (height). As shown in FIG. 1A, the joint structure 1 includes a joint plate 3 arranged over a pair of square steel pipes 21 and 21 arranged vertically with their end faces abutted against each other, and a joint plate 3. It has a plurality of high-strength bolts 4, 4, ... The square steel pipes 21 do not necessarily have to be brought into contact with each other (metal touch), and may be joined with a gap of a predetermined size (for example, about 10 mm).

The dimensions (width, length, pipe thickness, etc.) of the square steel pipe 21 constituting the steel pipe column 2 are not limited and may be appropriately determined.
As shown in FIG. 2, a semicircular recess 22 is formed in the center of the end of each surface of the square steel pipe 21 of the present embodiment. The recesses 22 and 22 of the pair of square steel pipes 21 and 21 are formed so as to face each other, and when the square steel pipes 21 are butted against each other, a circular working opening 23 is formed by the recesses 22 and 22 facing vertically. (See FIG. 1 (a)). The shape and dimensions of the recess 22 (working opening 23) are not limited as long as it is possible to form a working opening 23 having a shape into which a worker's arm, a high-strength bolt 4, or the like can be inserted. Instead, for example, it may be a rectangle. At the joint between the square steel pipes 21, four working openings 23 are formed by the recesses 22 provided in each of the square steel pipes 21. The arrangement of the recesses 22 is not limited, and may be formed on only one of the four surfaces of the square steel pipe 21, or may be formed on a pair of opposite side surfaces of the square steel pipe 21. Alternatively, it may be formed on two orthogonal sides of the square steel pipe 21 respectively.
Further, a plurality of bolt holes 24, 24, ... Are formed at the end of the square steel pipe 21. The bolt hole 24 is a through hole having a diameter through which the shaft portion 41 of the high-strength bolt 4 can be inserted. The plurality of bolt holes 24, 24, ... Are arranged so as to surround the periphery of the recess 22. That is, the plurality of bolt holes 24, 24, ... Are formed so as to be evenly arranged on the top, bottom, left and right of the work opening 23 with the square steel pipes 21 butted against each other. The number and arrangement of the bolt holes 24 are not limited, and may be appropriately determined.

As shown in FIGS. 1A and 1B, the joint plate 3 is a steel plate having a rectangular contour, and is attached across a pair of square steel pipes 21. The joint plate 3 is arranged on the outer surface and the inner surface on each of the four side surfaces of the square steel pipe 21. The shape of the joint plate 3 is not limited to a rectangle.
As shown in FIG. 3, a through hole 31 having the same shape as the working opening 23 is formed in the central portion of the joint plate 3 of the present embodiment. As with the work opening 23, the through hole 31 may have a shape in which a worker's arm, a high-strength bolt 4, or the like can be inserted, and does not necessarily have the same shape as the work opening 23. Further, the through hole 31 may be formed as needed, and if there is a surface on the side surface of the square steel pipe 21 in which the working opening 23 (recessed portion 22) is not formed, the through hole 31 is installed in the surface. It is not necessary to form a through hole 31 in the joint plate 3 to be formed.
Bolt holes 32 are formed in each joint plate 3 corresponding to the positions of the bolt holes 24 formed in the square steel pipe 21. The bolt hole 32 is a through hole having a diameter through which the shaft portion 41 of the high-strength bolt 4 can be inserted. The plurality of bolt holes 32, 32, ... Are evenly arranged on the top, bottom, left and right of the through hole 31 (working opening 23).

As shown in FIGS. 1A and 1B, the plurality of high-strength bolts 4, 4, ... Fasten the joint plate 3 to the side surface of the square steel pipe 21.
The high-strength bolt 4 inserts the shaft portion 41 into the bolt hole 24 of the square steel pipe 21 and the bolt hole 32 of the joint plate 3. When the nut 43 is fastened to the shaft portion 41 with the head portion 42 of the high-strength bolt 4 locked around the bolt hole 32, the inner and outer joint plates 3 sandwich the side surface (side wall) of the square steel pipe 21. The high-strength bolt 4 is arranged from the inside of the square steel pipe 21. That is, the head 42 of the high-strength bolt 4 is locked to the joint plate 3 attached to the inner surface of the square steel pipe 21, and the nut 43 is the joint plate 3 attached to the outer surface of the square steel pipe 21. It is locked to the surface.

When connecting the square steel pipes 21 to each other by the joint structure 1, first, the other square steel pipe 21 is placed on the upper end of one of the square steel pipes 21. At this time, the end faces of the double-sided steel pipes 21 and 21 are butted against each other. When abutting the end faces of the square steel pipe 21, the upper end of the other square steel pipe 21 may be pressed against the lower end of one square steel pipe 21 from below. When the square steel pipes 21 are brought into contact with each other, a joint plate 3 is previously attached to the inner surface of one of the square steel pipes 21, and the joint plate 3 is inserted inside the other square steel pipe 21. , The square steel pipes 21 are butted against each other. The joint plate 3 attached in advance is temporarily fixed with bolts or the like.
Next, the joint plate 3 is attached to the outer surface of the square steel pipes 21 and 21 straddling the double-sided steel pipes 21 and 21. Subsequently, the high-strength bolt 4 is inserted into the steel pipe column 2 (inside the square steel pipe 21) from the working opening 23, and the bolt hole 32 of the inner joint plate 3, the bolt hole 24 of the square steel pipe 21 and the outer joint plate are inserted. The shaft portion 41 is inserted through the bolt hole 32 of 3.
Then, the nut 43 is fastened to the shaft portion 41 penetrating the bolt holes 24 and 32 with a predetermined torque, and the joint plate 3 is fixed to the square steel pipes 21 and 21. By fastening with high-strength bolts 4, a frictional force is generated between the square steel pipe 21 and the joint plate 3. Therefore, the pair of square steel pipes 21 arranged above and below are joined by the frictional force with the joint plate 3 arranged across the both square steel pipes 21 and 21.

As described above, according to the joint structure 1 of the present embodiment, since the through hole 31 is formed in the central portion of the joint plate 3 corresponding to the position of the work opening 23, the joint is joined so as to avoid the work opening 23. There is no need to divide the plate 3. Therefore, even if the area of the joint plate 3 is reduced, the rigidity and proof stress required for joining the square steel pipes 21 can be secured. Further, the shear strength and rigidity can be ensured by the cross-sectional area of the joint plate 3.
Further, at the joint portion between the square steel pipes 21, one joint plate 3 is attached to each surface without being divided, so that the degree of freedom in arranging the high-strength bolt 4 is increased. Therefore, the shape of the joint plate 3 can be suppressed to the minimum necessary area, and the joint structure 1 can be economically formed. Further, by arranging the high-strength bolts 4 evenly on the upper, lower, left and right sides of the work opening 23, it is possible to evenly distribute and transmit the stress. Further, by arranging the high-strength bolt 4 on the flat surface portion near the corner portion, the stress at the corner portion can be efficiently transmitted.
Further, since the square steel pipes 21 are connected to each other by the joint plate 3 and the high-strength bolt 4, maintenance is easy. That is, if looseness of the high-strength bolt 4 is confirmed, it may be retightened, and if a defect occurs in the joint plate 3 or the high-strength bolt 4, it may be partially replaced, which is a large scale. No repair work required.
Further, by using the joint plate 3 and the high-strength bolt 4, the weather at the time of construction does not easily affect the quality as in welding.
Since the working opening 23 is formed at the center of the end portion of the side surface of the square steel pipe 21, the influence on the plastically processed corner portion is small, and the working opening 23 is less likely to be damaged during machining.

Next, the result of the structural analysis by the finite element method carried out for the joint structure 1 of the present embodiment will be described (Example). This analysis was carried out for the joint structure 1 in the case of connecting the square steel pipes 21 having 550 × 550 × 25 (BCR295, yield point 295N / mm ² ) to each other.
A circular through hole having a diameter of 150 mm was provided at the joint portion between the square steel pipes 21 as a working opening 23. A total of 32 bolt holes 24 are formed around the work opening 23. The bolt holes 24 are formed in 6 vertical rows and 6 horizontal rows, with 6 locations from the top and 2 stages from the bottom, and 4 locations on the left and right of the work opening 23 in the middle 2 stages. ing. The center distance between the bolt holes 24 adjacent to each other on the left, right, top and bottom was set to 60 mm. The center distance between the bolt holes 24 in the third and fourth stages was 90 mm, and the center distance between the bolt holes 24 in the third and fourth rows was 95 mm.
As shown in FIG. 4A, a steel plate (SM490, yield point 325N / mm ² ) having a plate thickness of 415 × 415 mm and a plate thickness of 25 mm was used for the joint plate 3 used for joining the square steel pipes 21 to each other. A through hole 31 having a diameter of 150 mm is formed in the center of the joint plate 3, and a total of 32 through holes 31 are formed around the through hole 31 corresponding to the positions of the bolt holes 24 formed in the square steel pipe 21. Bolt holes 32 are formed. The distance from the center to the edge of the bolt hole 32 formed along the outer circumference of the joint plate 3 was set to 40 mm.
M22 was used for the bolt, and the bolt axial force (tightening torque) was set to 205 kN.

In addition to this analysis, as Comparative Example 1, as shown in FIG. 4B, a rectangular steel plate (SM490, yield point 325N / mm ² ) having a width of 140 mm, a length of 530 mm, and a thickness of 25 mm was used as the joint plate 3A. We also analyzed the cases. The joint plates 3A are arranged on the left and right sides of the work opening 23, respectively. Each joint plate 3A is formed with two rows of vertically eight-stage bolt holes 32. The distance between the centers of the bolt holes 32 was 60 mm, and the distance from the center of the bolt holes 32 to the edge of the joint plate 3A was 40 mm.

Further, as Comparative Example 2, as shown in FIG. 4C, an analysis of the case where a steel plate (SM490, yield point 325N / mm ² ) having a width of 190 mm, a length of 410 mm, and a thickness of 25 mm is used as the joint plate 3B is also analyzed. went. The joint plates 3B are arranged on the left and right sides of the work opening 23, respectively. The joint plate 3B is formed with an arc-shaped recess 33 according to the position of the working opening 23. That is, the joint plate 3B of Comparative Example 2 has a shape in which the joint plate 3 of the embodiment is divided in the center in the left-right direction. The arrangement of the high-strength bolts 4 is the same as that of the embodiment, and each joint plate 3B is formed with 16 bolt holes 32 (32 in total).

In this analysis, a lateral force was applied to the upper square steel pipe 21 so that a shearing force was applied to the joint portion. FIG. 5 is a graph showing the relationship between the force point displacement calculated by the analysis and the shear force.
As shown in FIG. 5, according to the embodiment, the initial rigidity is increased by about 10% as compared with Comparative Examples 1 and 2. Further, in the examples, the decrease in yield strength with the progress of deformation is smaller than in Comparative Examples 1 and 2.
Further, when the deformation / contour diagram of FIG. 6 is confirmed, in Comparative Examples 1 and 2, slippage occurs between the steel pipe and the joint plates 3A and 3B, and displacement deformation occurs between the steel pipes. In the embodiment, no slip occurs, and the upper and lower steel pipes at the joint are deformed as a unit. Further, in the embodiment, the shear stress generated around the contact portion of the square steel pipe 21 and the joint plate 3 is smaller than that of Comparative Examples 1 and 2.
Therefore, it is necessary to attach one joint plate 3 to each surface of the square steel pipe 21 without dividing it, and to evenly arrange the high-strength bolts 4 around the work opening 23. It was confirmed that the joint structure 1 having rigidity and proof stress was formed.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and each of the above-mentioned components can be appropriately changed without departing from the spirit of the present invention.
For example, the application location of the joint structure 1 is not limited to the steel pipe column 2 as long as it is a joint portion between steel pipes.
Further, it is desirable that the square steel pipe 21 and the joint plate 3 are surface-treated as necessary so as to improve the frictional force.
Further, the materials and strengths of the square steel pipe 21 and the joint plate 3 are not limited, and may be appropriately determined.
In the above embodiment, the case where the square steel pipes 21 are joined to each other by frictional joining using the high-strength bolt 4 has been described, but the shearing force of the bolt shaft portion (shaft portion 41) and the base material (square steel pipe 21 and the joint plate) have been described. Square steel pipes 21 may be joined to each other by so-called bolt joining due to the support pressure of 3).

1 Fitting structure 2 Steel pipe column 21 Square steel pipe 22 Recessed 23 Work opening 24 Bolt hole 3 Fitting plate 31 Through hole 32 Bolt hole 4 High-strength bolt (bolt)
41 Shaft 42 Head 43 Nut

Claims (1)

It is a joint structure that joins a pair of square steel pipes with their end faces butted against each other .
A joint plate attached across the pair of square steel pipes,
It is provided with a plurality of bolts for fastening the joint plate and the square steel pipe.
A recess is formed in the center of each end of each of the square steel pipes so that a working opening is formed when the square steel pipes are joined to each other.
A through hole having the same shape as the working opening is formed in the central portion of the joint plate, and the joint plate is formed .
The joint structure is characterized in that the bolts are arranged vertically in addition to the left and right of the working opening .

Images