Welded structure of steel members and welding method of steel members

Abstract

This method suppresses deformation of the web due to thermal strain when welding steel plates to reinforce the area around through holes formed in the web of an H-beam. [Solution] A welded steel member is provided, comprising: an H-shaped steel having an H-shaped cross section including a first flange, a second flange and a web, with a through hole formed in the web that penetrates in the thickness direction; a steel plate arranged on top of the web around the through hole; and a weld formed between the web and the steel plate in a first region at a distance of 0.45 times or less the height of the H-shaped steel and a second region at a distance of 0.45 times or less the height of the H-shaped steel, wherein the dimensions of the steel plate in the height direction of the H-shaped steel are 0.6 times or more the height of the H-shaped steel, and no weld is formed in a third region between the first region and the second region.

Description

[Technical Field]

[0001] The present invention relates to a welded structure for steel members and a welding method for steel members. [Background technology]

[0002] H-shaped steel beams, used in applications such as beams, have a higher cross-sectional efficiency as the web becomes thinner and the flange thicker. Therefore, cross-sections with thin webs are sometimes used to conserve materials. For example, Patent Document 1 describes the use of a cross-section in a beam where the web width-to-thickness ratio, i.e., the ratio of the width (height dimension of the H-shaped steel) to the plate thickness, is in the range of over 60 and 75 or less. Patent Document 2 also describes that even H-shaped steel with a large web width-to-thickness ratio can be used as a structural element by satisfying conditions regarding the material strength of the H-shaped steel and the ratio of the cross-sectional area of ​​the web to the flange. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-001792 [Patent Document 2] Japanese Patent Publication No. 2022-111782 [Overview of the project] [Problems that the invention aims to solve]

[0004] On the other hand, when H-shaped steel beams used in buildings interfere with equipment piping, through-holes are formed in the web to allow the piping to pass through. In this case, steel plates are welded over the web to reinforce the area around the through-holes. However, especially when the web is thin, the resistance to bending deformation in the thickness direction of the web decreases, making it more susceptible to deformation due to thermal distortion from welding. If the web deforms due to thermal distortion, it may not be able to meet the required dimensional accuracy as a beam member, or irregular shapes may make joining the H-shaped steel to columns or beams difficult, or the quality of the joint may deteriorate. Because of these issues, the thickness of the web of the H-shaped steel needs to be set so that no problems occur during welding, which has been a factor hindering the thinning of the web.

[0005] Therefore, the present invention aims to provide a welded structure for steel members and a welding method for steel members that can suppress deformation of the web due to thermal strain when welding a steel plate to reinforce the area around a through hole formed in the web of an H-shaped steel. [Means for solving the problem]

[0006] [1] A welded steel member comprising: an H-shaped steel having an H-shaped cross section including a first flange, a second flange and a web, with a through hole formed in the web that penetrates in the thickness direction; a steel plate arranged on top of the web around the through hole; and a weld formed between the web and the steel plate in a first region at a distance of 0.45 times or less the height of the H-shaped steel and a second region at a distance of 0.45 times or less the height of the H-shaped steel, wherein the dimensions of the steel plate in the height direction of the H-shaped steel are 0.6 times or more the height of the H-shaped steel, and no weld is formed in a third region between the first region and the second region. [2] The steel plate is a rectangle having its longer side in the height direction of the H-shaped steel, a welded structure for a steel member as described in [1]. [3] The welded steel member structure according to [2], wherein the diameter of the through hole is 0.3 times or less the height of the H-shaped steel. [4] A welded structure of the steel member described in [1], wherein the web width-to-thickness ratio exceeds 75. [5] The welded structure of the steel member described in [4], wherein the thickness of the web is less than 6 mm. [6] The welded steel member structure according to [1], wherein the distance between the steel plate and the end of the H-shaped steel in the direction of the material axis is 1.5 times or less the height of the H-shaped steel. [7] A method for welding a steel member, comprising welding a steel plate to an H-shaped steel having an H-shaped cross section including a first flange, a second flange and a web, wherein a through hole is formed in the web, the welding method comprising the step of forming a weld between the web and the steel plate in a first region at a distance from the first flange of 0.45 times the height of the H-shaped steel and a second region at a distance from the second flange of 0.45 times the height of the H-shaped steel, and not comprising the step of forming the weld in a third region between the first region and the second region. [Effects of the Invention]

[0007] According to the above configuration, by forming a welded joint with the steel plate in the region of the web that is close to the flange and where the flange has a significant effect in restraining the deformation of the web, deformation of the web due to thermal strain can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a welded structure of a steel member according to one embodiment of the present invention. [Figure 2] This is a view along the line II-II in Figure 1. [Figure 3] This figure shows a modified example of a welded structure of a steel member according to an embodiment of the present invention. [Figure 4] This is a diagram showing a test specimen of a welded steel member structure. [Figure 5] This is a view along the VV line in Figure 4. [Figure 6] This graph shows how the amount of deformation δ of the web changes with the size of the steel plate. [Figure 7]It is a graph showing the change in the web deformation amount δ depending on the size of the H-shaped steel and the presence or absence of an area where no welded portion is formed.

Embodiment for Carrying Out the Invention

[0009] Hereinafter, exemplary embodiments of the present invention will be described in detail while referring to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] FIG. 1 and FIG. 2 are views showing a welding structure of a steel member according to an embodiment of the present invention. FIG. 1 is a view taken along the line I-I of FIG. 2, and FIG. 2 is a view taken along the line II-II of FIG. 1. In the illustrated example, the welding structure 1 includes an H-shaped steel 2 having an H-shaped cross section including flanges 21 and 22 and a web 23, a reinforcing steel plate 3, and welded portions 41 and 42 formed between the H-shaped steel 2 and the reinforcing steel plate 3. The H-shaped steel 2 may be a rolled H-shaped steel in which the flanges 21 and 22 and the web 23 are integrally formed, or an assembled H-shaped steel in which the flanges 21 and 22 and the web 23 are formed as separate steel plates and then welded. A through hole 24 penetrating the web 23 in the plate thickness direction is formed in the H-shaped steel 2, and the reinforcing steel plate 3 is disposed overlapping the web 23 around the through hole 24. A through hole 34 overlapping the through hole 24 is also formed in the reinforcing steel plate 3. The welded portion 41 is formed between the web 23 and the reinforcing steel plate 3 in the first region R1 on the flange 21 side. The region R1 is a region where the distance from the flange 21 is 0.45 times or less the height H of the H-shaped steel 2. The welded portion 42 is formed between the web 23 and the reinforcing steel plate 3 in the second region R2 on the flange 22 side. The region R2 is a region where the distance from the flange 22 is 0.45 times or less the height H. In the present embodiment, the dimension of the reinforcing steel plate 3 in the height direction of the H-shaped steel 2 is 0.6 times or more the height of the H-shaped steel 2, and no welded portion is formed in the third region R3 between the first region R1 and the second region R2.

[0011] In this embodiment, when welding the reinforcing steel plate 3 to the web 23 around the through hole 24, the weld is not formed in areas of the web 23 that are far from the flanges 21 and 22 and where the effect of the flanges 21 and 22 in restraining the deformation of the web 23 is small. Furthermore, the dimensions of the reinforcing steel plate in the height direction of the H-beam 2 are set to be at least a predetermined ratio to the height of the H-beam 2 so that the welds of the edges of the reinforcing steel plate 3 along the material axis direction of the H-beam 2 are close to the flanges 21 and 22. By configuring it in this way, deformation of the web due to thermal strain is suppressed. This configuration is effective when the web is thin, specifically the web width-to-thickness ratio, i.e., the plate thickness t w The ratio of width d (height dimension of H-beam 2) to width d / t w If it exceeds 75, furthermore, the web plate thickness t w This is particularly effective when the thickness is less than 6 mm. Note that the thickness of the web 23 is t w The lower limit is not particularly limited, but is the thickness t of a sheet metal that can be manufactured under normal circumstances. w The thickness is 2.3 mm or more. When the web width-to-thickness ratio is large, the thickness of the web 23 is t w In addition to being thin, the height d of the web 23 is large, and deformation of the web 23 due to thermal distortion during welding is likely to occur near the height center of the H-beam 2, which is far from the flanges 21 and 22. As in this embodiment, by forming welds 41 and 42 in regions R1 and R2 close to the flanges 21 and 22, and not forming welds in region R3 far from the flanges 21 and 22, it is possible to suppress deformation of the web 23 due to thermal distortion while thinning the web 23 and improving cross-sectional efficiency. In order to secure the weld length by making the most of the effect of the flanges 21 and 22 in constraining the deformation of the web 23, it is preferable to form the welds 41 and 42 symmetrically with respect to the height center of the H-beam 2 within regions R1 and R2.

[0012] The shape of the through-hole formed in the web 23 of the H-shaped steel 2 is not particularly limited, and may be, for example, circular as in the illustrated example or polygonal. Further, the through-hole may be arranged eccentrically with respect to the height center of the H-shaped steel 2, and a plurality of through-holes may be arranged in the height direction or the material axis direction of the H-shaped steel 2. The size of the through-hole 24 is determined, for example, by the arrangement of equipment piping or the like to be passed through. However, when the through-hole 24 is small with respect to the height H of the H-shaped steel 2, if a reinforcing steel plate 3 of a size sufficient for the size of the through-hole 24 is arranged, the reinforcing steel plate may exist only near the height center of the H-shaped steel, and it may be impossible to form a welded portion in the regions R1, R2 close to the flanges 21, 22. In such a case, as in the example shown in FIG. 1, the reinforcing steel plate 3 may be made rectangular with a long side in the height direction of the H-shaped steel 2, and a sufficient welding length may be ensured between the reinforcing steel plate 3 and the web 23 within the regions R1, R2. Thereby, it is possible to cope even when the through-hole 24 is small, specifically, for example, when the diameter is 0.3 times or less of the height H. The diameter of the through-hole 24 may exceed 0.3 times the height H. The size of the through-hole 24 is the diameter when the through-hole is circular, and is the size of the range in which the through-holes are arranged when a plurality of through-holes are arranged. On the other hand, the through-hole 34 formed in the reinforcing steel plate 3 does not necessarily have to be the same shape as the through-hole 24, but in the case of being circular, for example, it is preferable that the diameter error is about ±4 mm.

[0013] Furthermore, in the region near the end of the H-shaped steel 2 in the axial direction, the side ends of the web 23 are open, so the deformation of the web 23 is less constrained compared to the intermediate portion. Also, since the ends of the H-shaped steel 2 are often joined to other members by welding or bolting, deformation of the web 23 due to thermal distortion of welding may affect the quality of the joint with the other members. Therefore, for example, as shown in Figure 1, if the distance e between the reinforcing steel plate 3 and the end of the H-shaped steel 2 in the axial direction, specifically the distance from the edge of the roughly rectangular reinforcing steel plate 3 closest to the end of the H-shaped steel 2 to the end of the H-shaped steel 2 is less than 1.5 times the height of the H-shaped steel 2, a welding structure in which welds are formed only in regions R1 and R2 may be adopted as described above. In this case, a welding structure in which welds are also formed in region R3 may be adopted in the other parts of the H-shaped steel 2.

[0014] The welds 41 and 42 are, for example, fillet welds. In the illustrated example, the process of forming the weld 41 includes welding the edge of the reinforcing steel plate 3 along the flange 21 to the web 23, and welding the edge of the H-shaped steel 2 along the height direction to the web 23, but the order of these steps is not limited. Similarly, when forming the weld 42, welding may start from the edge of the reinforcing steel plate 3 along the flange 22, or from the edge of the H-shaped steel 2 along the height direction. The order in which the welds 41 and 42 are formed is also not particularly limited.

[0015] While deformation of the web 23 due to thermal strain can also be suppressed by using a jig to restrain the deformation of the web 23 when forming the weld between the H-shaped steel 2 and the reinforcing steel plate 3, or by performing tap welding to intermittently form weld beads, the configuration in this embodiment, which separates the welds 41 and 42, is advantageous because it does not require the effort of setting up jigs, and does not increase the labor required for construction due to the increased number of welds.

[0016] FIG. 3 is a diagram showing a modification of the welding structure of the steel member according to the embodiment of the present invention. In the illustrated example, the weld formed in the region R1 on the flange 21 side is separated into two welds 41A and 41B, and the weld formed in the region R2 on the flange 22 side is separated into two welds 42A and 42B. When the required weld length can be ensured without forming a weld in the region R3 between the regions R1 and R2, the welds on the sides along the flanges 21 and 22 of the reinforcing steel plate 3 may be separated as in the example shown in FIG. 3. The distance between the welds on the sides along the flanges 21 and 22 (between the welds 41A and 41B, and between the welds 42A and 42B) may be different from the distance between the welds on the sides along the height direction of the H-shaped steel 2 (between the welds 41A and 42A, and between the welds 41B and 42B).

[0017] Hereinafter, the results of tests for verifying the effects of the embodiments of the present invention as described above will be described. Test specimens of the welding structure of the steel member as shown in FIGS. 4 and 5 were fabricated, and the amount of web deformation due to welding thermal strain was measured. Note that FIG. 4 is a view taken along the arrow in the IV-IV line of FIG. 5, and FIG. 5 is a view taken along the arrow in the V-V line of FIG. 4. The dimensions of each test specimen are shown in Table 1. B is the flange width, t f is the flange plate thickness, and (H - 2t f ) / t w is the width-to-thickness ratio of the web. φ is the diameter of the circular through-hole, H pl , B pl are the dimensions of each side (the side in the height direction of the H-shaped steel and the side in the material axis direction) of the rectangular reinforcing steel plate, t plθ is the thickness of the reinforcing steel plate. In specimens No. 3 and 6, the weld is formed around the entire circumference of the reinforcing steel plate. In the other specimens, the weld is formed only in the regions on both flange sides, but the width h of the region where no weld is formed on the web near the center in the height direction of the H-beam differs. In each example, the weld was a fillet weld, and downward gas shielded arc welding was performed using YGW18 (JIS Z3312) as the welding wire and CO2 as the shielding gas. The average welding current for each specimen was 114A to 134A, the average welding voltage was 18.3V to 20.4V, and the average welding heat input was 4.2kJ / cm to 6.0kJ / cm. The amount of deformation δ in the thickness direction at the center of the web at the ends in the material axis direction of the H-beam was measured before and after welding. Furthermore, the standard for deformation δ is 1 / 150 of the height H (δ=3mm when H=450mm), which is shown as the management tolerance for steel frame accuracy inspection standards in the Architectural Institute of Japan's "Standard Specifications for Building Construction JASS6 Steel Frame Construction".

[0018] [Table 1]

[0019] Figure 6 is a graph showing the change in web deformation δ depending on the size of the reinforcing steel plate. In test specimens No. 1 and 2, a relatively small through-hole with a diameter of φ = 135 mm (0.3 times the height H of the H-beam) was formed in an H-beam with dimensions of H-450 × 160 × 3.6 × 6.0. In test specimen No. 1, a reinforcing steel plate of a sufficient size for the size of the through-hole, specifically a square of 210 mm × 210 mm, was placed. In this case, no weld was formed between the web and the reinforcing steel plate in the area with a width of h = 70 mm near the center of the H-beam in the height direction, but the web deformation δ exceeded the standard value. In contrast, in test specimen No. 2, the reinforcing steel plate was stretched in the height direction of the H-beam relative to the size of the through-hole, forming a rectangle with a height of 350 mm and a width of 210 mm. In test specimen No. 2, when no weld was formed between the web and the reinforcing steel plate in a region with a width h = 130 mm near the center of the H-beam in the height direction, the deformation amount δ of the web fell below the standard value. From this result, as shown in other examples later, in addition to not forming welds in regions where the distance from the flange is 0.45 times the height H, the dimensions of the reinforcing steel plate in the height direction of the H-beam should be considered. pl It is desirable to increase the size to a certain extent and to form the welded section along the flange of the reinforcing steel plate close to the flange. Specifically, from the results of the above test specimens No. 1 and 2, the dimension H of the reinforcing steel plate in the height direction of the H-beam is pl It is desirable that the height H of the H-beam be at least 0.6 times the height H. pl It is more than 0.6 times the height H.

[0020] Figure 7 is a graph showing the change in web deformation δ depending on the size of the H-beam and the presence or absence of areas where welds are not formed. In test specimens No. 3 to 5, a through hole with a diameter of φ=225 mm (0.5 times the height H of the H-beam) was formed in an H-beam with dimensions of H-450 × 160 × 3.6 × 6.0, and a 350 mm × 350 mm square reinforcing steel plate was placed there. In this case, in test specimen No. 3, where welds were formed around the entire circumference of the reinforcing steel plate, the web deformation δ greatly exceeded the standard value. In test specimens No. 4 and 5, when welds were not formed between the web and the reinforcing steel plate in areas with widths h=50 mm and 130 mm, respectively, near the center of the height direction of the H-beam, the web deformation δ fell below the standard value. In test specimens No. 6 and 7, an H-shaped steel beam with dimensions H-450×185×4.5×6.0 had a through-hole with a diameter of φ=225mm, and a 350mm×350mm square reinforcing steel plate was placed inside. In this case, even in test specimen No. 6, where the weld was formed around the entire circumference of the reinforcing steel plate, the web deformation amount δ was below the standard value but was still relatively large. In contrast, in test specimen No. 7, where no weld was formed in the area with a width of h=50mm near the center of the height direction of the H-shaped steel beam, the deformation amount δ was reduced. When the width h=50mm, h / H=0.11, meaning that the weld is formed in an area where the distance from the flange is 0.45 times the height H or less. [Explanation of Symbols]

[0021] 1...Welded structure, 2...H-beam, 21...Flange, 22...Flange, 23...Web, 24...Through hole, 3...Reinforcement steel plate, 34...Through hole, 41, 41A, 41B, 42, 42A, 42B...Welded joint.

Claims

1. An H-shaped steel having an H-shaped cross section including a first flange, a second flange, and a web, with a through hole formed in the web that penetrates in the thickness direction, A steel plate is arranged around the through hole, overlapping the web, A welded portion formed between the web and the steel plate in a first region where the distance from the first flange is 0.45 times or less the height of the H-beam, and in a second region where the distance from the second flange is 0.45 times or less the height of the H-beam. Equipped with, The dimensions of the steel plate in the height direction of the H-shaped steel are 0.6 times or more the height of the H-shaped steel. A welded structure for a steel member, wherein no weld is formed in the third region between the first region and the second region.

2. The welded steel member structure according to claim 1, wherein the steel plate is a rectangle having its longer side in the height direction of the H-shaped steel.

3. The welded steel member structure according to claim 2, wherein the diameter of the through hole is 0.3 times or less the height of the H-shaped steel.

4. The welded structure of a steel member according to claim 1, wherein the width-to-thickness ratio of the web exceeds 75.

5. The welded steel member structure according to claim 4, wherein the thickness of the web is less than 6 mm.

6. The welded steel member structure according to claim 1, wherein the distance between the steel plate and the end of the H-shaped steel in the direction of the material axis is 1.5 times or less the height of the H-shaped steel.

7. A welding method for a steel member, comprising welding a steel plate to an H-shaped steel beam having an H-shaped cross-section including a first flange, a second flange, and a web, wherein a through hole is formed in the web, and the steel plate is positioned on top of the web around the through hole, The process includes forming a weld between the web and the steel plate in a first region where the distance from the first flange is 0.45 times or less the height of the H-shaped steel, and in a second region where the distance from the second flange is 0.45 times or less the height of the H-shaped steel. A method for welding steel members, which does not include the step of forming the welded portion in a third region between the first region and the second region.

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