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; a first weld formed between the web and the steel plate on the first flange side; and a second weld formed between the web and the steel plate on the second flange side, separated from the first weld.

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, such as those used as beams in a building, interfere with equipment piping, through-holes are formed in the web to allow the piping to pass through. In this case, to compensate for the decrease in structural performance of the H-shaped steel due to the formation of the through-holes, steel plates are welded over the web. However, especially when the web is thin, the resistance to bending deformation in the thickness direction of the web decreases, making the web more susceptible to deformation due to thermal strain from welding. If the web deforms due to thermal strain, it may not be able to satisfy 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 problems, the thickness of the web of the H-shaped steel needs to be set so that no problems occur during welding, and this 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; a first weld formed between the web and the steel plate on the first flange side; and a second weld formed between the web and the steel plate on the second flange side, which is separated from the first weld. [2] A welded structure of the steel member described in [1], wherein the web width-to-thickness ratio exceeds 75. [3] The welded structure of the steel member described in [2], wherein the thickness of the web is less than 6 mm. [4] The welded structure of the steel member according to [1], wherein the distance between the first weld and the second weld is 0.1 times or more the height of the H-shaped steel. [5] The welded structure for a steel member according to [1], wherein the first weld and the second weld are formed symmetrically with respect to the height center of the H-shaped steel. [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, and the steel plate is arranged to overlap the web around the through hole, the method comprising the steps of forming a first weld between the web and the steel plate on the first flange side, and forming a second weld between the web and the steel plate on the second flange side and at a position separate from the first flange side. [Effects of the Invention]

[0007] According to the above configuration, by not forming welds with the steel plate in areas of the web that are far from the flange and where the flange has little 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 the change in web deformation δ due to the separation of the welded joint. [Figure 7] This graph shows the allowable separation distance h of the welded joint in the example being considered. [Modes for carrying out the invention]

[0009] With reference to the accompanying drawings below, exemplary embodiments of the present invention will be described in detail. 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 diagrams showing a welding structure of a steel member according to an embodiment of the present invention. FIG. 1 is a view taken in the direction of the arrow along the line I-I of FIG. 2, and FIG. 2 is a view taken in the direction of the arrow 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 steel plate 3, and welds 41 and 42 formed between the H-shaped steel 2 and the 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 together. A through hole 24 penetrating the web 23 in the plate thickness direction is formed in the H-shaped steel 2, and the 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 steel plate 3. The weld 41 is formed between the web 23 and the steel plate 3 on the flange 21 side. The weld 42 is formed between the web 23 and the steel plate 3 on the flange 22 side. In the present embodiment, the weld 41 and the weld 42 are separated. More specifically, no weld is formed between the web 23 and the steel plate 3 in the section of the distance h near the height center of the H-shaped steel 2.

[0011] In the present embodiment, when welding the steel plate 3 to the web 23 around the through hole 24, by not forming a weld in the region of the web 23 far from the flanges 21 and 22 where the effect of the flanges 21 and 22 restraining the deformation of the web 23 is small, the deformation of the web due to thermal strain is suppressed. Such a configuration is effective when the web is thin. Specifically, when the width-thickness ratio of the web, that is, the ratio d / t , w , w , w of the width d (dimension in the height direction of the H-shaped steel 2) to the plate thickness t w exceeds 75, and further when the plate thickness t of the web wThis 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 of welding is likely to occur near the height center of the H-beam 2, where it is far from the flanges 21 and 22. By separating the welded parts 41 and 42 as in this embodiment, deformation of the web 23 due to thermal distortion can be suppressed, and the web 23 can be made thinner to improve cross-sectional efficiency. The distance h between the welded parts 41 and 42 is preferably 0.1 times or more the height H of the H-beam 2. There is no particular upper limit to the distance h, but as will be described later, it is preferable that it be 0.45 times or less the height H in order to secure a sufficient weld length in the web 23. Furthermore, in order to secure the weld length by making the most of the effect of the flanges 21 and 22 in restraining the deformation of the web 23, it is preferable to form the welded parts 41 and 42 symmetrically with respect to the height center of the H-beam 2, that is, within the same distance range with respect to each of the flanges 21 and 22.

[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 may be 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 the equipment piping or the like to be passed through. However, in order to suppress the deformation of the web 23 due to the thermal strain of welding by arranging a steel plate 3 having a sufficient size with respect to the size of the through-hole 24 and separating the welded portions 41 and 42 as in the above-described embodiment, it is preferable that the size of the through-hole 24 in the height direction of the H-shaped steel 2 is 0.3 times or more of the height H of the H-shaped steel 2. 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. When the through-hole is small and thus the steel plate arranged around the through-hole is also small compared to the height of the H-shaped steel, the steel plate exists only near the height center of the H-shaped steel, and even if the welded portion is separated, the effect of restraining the deformation by the flange may be reduced. On the other hand, the through-hole 34 formed in the steel plate 3 does not necessarily have to have the same shape as the through-hole 24. However, for example, in the case of a circular shape, it is preferable that the diameter error is about ±4 mm.

[0013] Further, in the region near the end in the material axis direction of the H-shaped steel 2, since the side end portion of the web 23 is open, the deformation of the web 23 is less likely to be restrained compared to the intermediate portion. Further, since the end portion of the H-shaped steel 2 is often joined to other members by welding, bolt joining, or the like, the deformation of the web 23 due to the thermal strain of welding may affect the quality of the joint portion with the other members. Therefore, for example, as shown in FIG. 1, when the distance e between the steel plate 3 and the end in the material axis direction of the H-shaped steel 2, specifically, the distance from the side closest to the end of the H-shaped steel 2 to the end of the H-shaped steel 2 of the steel plate 3 which is substantially rectangular is less than 1.5 times the height of the H-shaped steel 2, a welding structure in which the welded portions 41 and 42 are separated as described above may be adopted. In this case, in the other portions of the H-shaped steel 2, a welding structure in which the welded portion is not separated may be adopted.

[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 substantially rectangular 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 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 distortion 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 steel plate 3, or by performing tap welding to intermittently form the weld bead, 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] Figure 3 shows a modified example of the welded structure of a steel member according to an embodiment of the present invention. In the illustrated example, the weld on the flange 21 side is separated into two welds 41A and 41B, and the weld on the flange 22 side is separated into two welds 42A and 42B. If the necessary welding length can still be secured even if an appropriate separation distance h is left between the weld on the flange 21 side and the weld on the flange 22 side, the welds on the sides of the steel plate 3 along the flanges 21 and 22 may be separated as in the example shown in Figure 3. The distance between the welds on the sides along the flanges 21 and 22 (between welds 41A and 41B, and between welds 42A and 42B) may be different from the distance h between the welds on the sides along the height direction of the H-shaped steel 2 (between welds 41A and 42A, and between welds 41B and 42B).

[0017] The following describes the results of tests for verifying the effects of the embodiments of the present invention as described above. Test specimens of the welding structure of steel members as shown in FIGS. 4 and 5 were fabricated, and the amount of web deformation due to the thermal strain of welding was measured. Note that FIG. 4 is a view seen in the arrow direction along line IV-IV of FIG. 5, and FIG. 5 is a view seen in the arrow direction along line V-V 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-thickness ratio of the web. φ is the diameter of the through-hole which is circular, H pl , B pl are the lengths of each side of the rectangular steel plate (the side in the height direction of the H-shaped steel and the side in the material axis direction), and t pl is the steel plate thickness. In each test specimen, the steel plate is a 350 mm × 350 mm square. In the test specimens of No. 1 and 4, the welded part between the web and the steel plate is not separated. That is, in these examples, the welded part is formed over the entire circumference of the steel plate. In the test specimens of No. 2, 3, and 5, the welded part is separated. In these examples, the welded parts are formed symmetrically with respect to the height center of the H-shaped steel and are separated from each other by a distance h. In each example, the welded part is a fillet weld, and downward gas shielded arc welding using YGW18 (JIS Z3312) for the welding wire and CO2 for the shielding gas was performed. The welding current in each test specimen was 108 A to 128 A on average, the welding voltage was 16.3 V to 20.9 V on average, and the heat input of welding was 4.8 kJ / cm to 5.7 kJ / cm on average. The amount of deformation δ in the plate thickness direction at the center of the web at the end in the material axis direction of the H-shaped steel before and after welding was measured. Note that as the reference for the amount of deformation δ, 1 / 150 of the height H (δ = 3 mm when H = 450 mm) shown as the management tolerance of the steel structure accuracy inspection standard in the "Architectural Construction Standard Specification JASS6 Steel Structure Work" of the Architectural Institute of Japan is used.

[0018]

Table 1

[0019] Figure 6 is a graph showing the change in web deformation δ due to the separation of the weld. In the case of H-beams with dimensions H-450×160×3.6×6.0 (test specimens No. 1-3), the web deformation δ in test specimen No. 1, where the weld was not separated, significantly exceeded the standard value. In contrast, in test specimen No. 2, where the weld was separated and the distance h between them was set to 50 mm, the deformation δ was significantly smaller and fell below the standard value. In test specimen No. 3, where the distance h was further increased to 130 mm, the deformation δ was even smaller. In the case of H-beams with dimensions H-450×185×4.5×6.0 (test specimens No. 4, 5), the web deformation δ did not exceed the standard value even in test specimen No. 4, where the weld was not separated, but the deformation δ was even smaller in test specimen No. 8, where the weld was separated and the distance h between them was set to 50 mm. These results show that separating the weld is effective in reducing the deformation amount δ, and that the deformation amount δ can be sufficiently reduced by setting the separation distance h of the weld to 0.1 times or more the height H of the H-beam (h / H > 0.1 in all of the No. 2, 3, and 5 test specimens).

[0020] In the welded steel member structure described above, the steel plate placed around the through-hole formed in the web of the H-beam needs to compensate for the decrease in structural performance of the H-beam caused by the formation of the through-hole. Therefore, even if a configuration is adopted in which the web of the H-beam and the steel plate are not partially welded, as in the embodiment of the present invention, the steel plate must sufficiently compensate for the decrease in structural performance of the H-beam caused by the formation of the through-hole. Accordingly, below we will examine the allowable separation distance h of the welded joint, assuming that the structural performance of the H-beam is sufficiently compensated for by the steel plate. For the verification, we targeted H-beams with a web width-to-thickness ratio exceeding 75 and a height H of 400 mm to 450 mm or more, which is common as a beam member in non-residential buildings. Table 2 shows the dimensions of the example examined. Steel type of steel constituting the H-beam (yield stress σ y 235 N / mm 2 and 325 N / mm 2 (2 options), diameter of the through hole φ (2 options: 0.6H or 0.4H relative to the height H), and thickness of the steel plate t plThe variables were (3.6mm, 4.5mm, 6mm, 9mm, or 12mm). The steel plate placed around the through-hole was a square with sides of 300mm or 350mm and was joined to the web of the H-beam by fillet welds all around.

[0021] [Table 2]

[0022] In calculating the welding length required for stress transmission borne by the steel plate welded to the web, the following formulas (1) to (14) described in Japanese Patent Publication No. 5908282 were used.

[0023]

number

[0024] Figure 7 is a graph showing the allowable weld separation distance h in the study example. In the study example, for H-beams with heights H of 400 mm and 450 mm, and through-hole diameters φ of 0.6 H and 0.4 H, when the minimum weld length required to keep the web deformation amount when a load is applied to the H-beam to 1 / 150 or less of the height H was secured, the weld separation distance h was calculated as h / H in all cases, and h / H > 0.10. From this result, it was found that even when the weld separation distance h is set to 0.1 times or more of the H-beam height H, as in the example shown in Figure 6 above, to reduce web deformation due to thermal distortion of welding, the steel plate can sufficiently compensate for the decrease in structural performance of the H-beam due to the formation of the through-hole. On the other hand, even when a relatively large separation distance h can be allowed in the study example, h / H < 0.45, so the separation distance h is often 0.45 times or less of the height H. The actual separation distance h is determined based on the dimensions of the H-beam and through-hole, for example, by calculating the welding length as shown in the example above. [Explanation of Symbols]

[0025] 1...Welded structure, 2...H-beam, 21...Flange, 22...Flange, 23...Web, 24...Through hole, 3...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 placed on top of the web around the through hole, A first welded portion formed between the web and the steel plate on the first flange side, A second weld is formed between the web and the steel plate on the second flange side, and is separated from the first weld. A welded structure for steel members equipped with [the following features].

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

3. The welded steel member structure according to claim 2, wherein the thickness of the web is less than 6 mm.

4. The welded structure for a steel member according to claim 1, wherein the distance between the first weld and the second weld is 0.1 times or more the height of the H-shaped steel.

5. The welded structure for a steel member according to claim 1, wherein the first weld and the second weld are formed symmetrically with respect to the height center of the H-shaped steel.

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 steps of forming a first weld between the web and the steel plate on the first flange side, and The process of forming a second weld between the web and the steel plate at a position on the second flange side and separate from the first flange side. A welding method for steel members including steel members.

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