Welded structure of steel members and welding method of steel members

Abstract

This suppresses web deformation caused by thermal distortion during welding when welding steel plates to H-beams. [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, wherein the width-to-thickness ratio of the web exceeds 75; a steel plate arranged to intersect the material axis direction of the H-shaped steel; a first weld formed between the first flange and the web and the steel plate; and a second weld formed between the second flange and the web and the steel plate, which is 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 Initiative] [Problems that the invention aims to solve] 【0004】 On the other hand, H-beams sometimes have steel plates, called stiffeners or gusset plates, welded to them so as to intersect the axial direction of the H-beam. In this case, the steel plates are welded to the flange and web of the H-beam, but 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 the irregular shape may make it difficult to join the H-beam to a column or beam, or the quality of the joint may deteriorate. Because of these problems, the thickness of the web of the H-beam needs to be set so that no problems occur during welding, and this has been a factor that has hindered 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 distortion during welding when welding steel plates to H-shaped steel with a large web width-to-thickness ratio. [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, wherein the width-to-thickness ratio of the web exceeds 75; a steel plate arranged to intersect the material axis direction of the H-shaped steel; a first weld formed between the first flange and the web and the steel plate; and a second weld formed between the second flange and the web and the steel plate, which is separated from the first weld. [2] The welded structure of the steel member described in [1], wherein the thickness of the web is less than 6 mm. [3] The welded structure of the steel member according to [1], wherein the distance between the first weld and the second weld is 0.2 times or more the height of the H-shaped steel. [4] The welded structure of the 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. [5] 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 axial direction is 1.5 times or less the height of the H-shaped steel. [6] A welding method for 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 the width-to-thickness ratio of the web exceeds 75, the welding method comprising the steps of welding between the first flange and the steel plate, welding between the web and the steel plate on the first flange side, welding between the web and the steel plate on the second flange side at a position separate from the first flange side, and welding between the second flange and the steel plate. [Effects of the Invention] 【0007】 With the above configuration, welds are formed not only on the flange but also on the web to ensure a sufficient weld length, and welds are not formed 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, thereby suppressing deformation of the web due to thermal strain. [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 is a diagram showing a test specimen of a welded steel member structure. [Figure 4] This is a view along the line IV-IV in Figure 3. [Figure 5] This graph shows the relationship between distance e and web deformation δ in an example where the weld is not separated. [Figure 6] This graph shows the separation of the weld when the distance e at which the web deformation was greatest was 200 mm, and the effect of the separation distance h on the web deformation δ. [Figure 7]This is a diagram for explaining the relationship between the dimensions of the attachment part between a steel plate welded to an H-shaped steel and other members and the welding length. [Figure 8] This is a graph showing the presence or absence of separation of the welded part and the relationship between the distance e and the amount of web deformation δ. [Figure 9] This is a graph showing the relationship between the bending rigidity D of the web and the amount of web deformation δ. 【Embodiments for Carrying Out the Invention】 【0009】 Hereinafter, exemplary embodiments of the present invention will be described in detail with reference 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 duplicate descriptions are omitted. 【0010】 FIG. 1 and FIG. 2 are diagrams showing the 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, 22 and a web 23, a steel plate 3, and welding parts 41, 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, 22 and the web 23 are integrally formed, or an assembled H-shaped steel in which the flanges 21, 22 and the web 23 are formed as separate steel plates and then welded. The steel plate 3 is, for example, called a stiffener or a gusset plate and is arranged so as to intersect the material axis direction of the H-shaped steel 2. The welding part 41 is formed between the upper flange 21, the web 23, and the steel plate 3. The welding part 42 is formed between the lower flange 22, the web 23, and the steel plate 3. In the present embodiment, the welding part 41 and the welding part 42 are separated. More specifically, in the section of the distance h near the height center of the H-shaped steel 2, no welding part is formed between the web 23 and the steel plate 3. 【0011】 In this embodiment, in addition to the flanges 21 and 22, welded joints 41 and 42 are also formed on the web 23 to ensure a sufficient weld length. Furthermore, welded joints are 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, thereby suppressing deformation of the web due to thermal strain. This configuration is effective when the web is thin, specifically when the web width-to-thickness ratio, i.e., the plate thickness t, is low. 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 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 0.2 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 0.8 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】 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 middle section. 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 2, if the distance e between the steel plate 3 and the end of the H-shaped steel 2 in the axial direction is less than 1.5 times the height of the H-shaped steel 2, a welded structure in which the welds 41 and 42 are separated as described above may be adopted. In this case, a welded structure in which the welds are not separated may be adopted for the other parts of the H-shaped steel 2. 【0013】 The welds 41 and 42 are, for example, fillet welds. In order to ensure a sufficient weld length even without forming a weld on a portion of the web 23, it is preferable that the welds 41 and 42 are formed between the flanges 21 and 22 and the steel plate 3 over the entire width of the flanges 21 and 22, excluding the portion that intersects with the web 23. The process of forming the weld 41 includes the process of welding between the flange 21 and the steel plate 3, and the process of welding between the web 23 on the flange 21 side and the steel plate 3, but the order of these processes is not limited. In other words, when forming the weld 41, welding may be done starting from the flange 21 or from the web 23. Similarly, when forming the weld 42, welding may be done starting from the flange 22 or from the web 23. The order in which the welds 41 and 42 are formed is also not particularly limited. 【0014】 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. 【0015】 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 welded structure of steel members as shown in FIGS. 3 and 4 were fabricated, and the amount of web deformation due to welding thermal strain was measured. Note that FIG. 3 is a view taken along the arrow III-III line of FIG. 4, and FIG. 4 is a view taken along the arrow IV-IV line of FIG. 3. The dimensions of each test specimen are shown in Table 1. The cross-sectional dimensions of the H-shaped steel used for the test specimens are two types: H-450×200×3.6×6.0 and H-450×185×4.5×6.0. 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. Note that H - 2t f = d. When the web plate thickness t w = 3.6 mm, the width-thickness ratio d / t w ≈ 122, and when the web plate thickness t w = 4.5 mm, the width-thickness ratio d / t w ≈ 97. For these H-shaped steels, a steel plate is welded at a position separated by a distance e from the end in the material axis direction. In the test specimens No. 1 to 4, 8 to 10, the welded part between the H-shaped steel and the steel plate is not separated. That is, in these examples, the welded part is formed over the entire width of the upper and lower flanges and the web. In the test specimens No. 5 to 7, 11 to 13, the welded part is separated. In these examples, the welded part is formed symmetrically with respect to the center of the height of the H-shaped steel and is 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 158 A to 169 A on average, the welding voltage was 20.9 V to 21.9 V on average, and the heat input per unit length of welding was 8.6 kJ / cm to 12.4 kJ / cm on average. The amount of deformation δ in the thickness direction of the center of the web at the end in the material axis direction of the H-shaped steel was measured before and after welding. Note that as a reference for the amount of deformation δ, 1 / 150 of the height H (when H = 450 mm, δ = 3 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 Japan Society of Civil Engineers is used. 【0016】 【Table 1】 【0017】 Figure 5 is a graph showing the relationship between distance e and web deformation δ in an example where the weld is not separated. Distance e is the distance between the steel plate welded to the H-beam and the end of the H-beam in the axial direction. In Nos. 2, 3, 8, and 9, the ratio of deformation δ to height H, δ / H, exceeds the standard value. Therefore, depending on the dimensions of the H-beam, if the web width-to-thickness ratio exceeds 75 and the distance e between the steel plate welded to the H-beam and the end of the H-beam in the axial direction is less than 1.5 times the height H of the H-beam, the web deformation δ due to thermal strain from welding to the steel plate may be large. In particular, if the distance e is between 0.3 times and 1.0 times the height H, the web deformation δ due to thermal strain from welding will be large. 【0018】 Figure 6 is a graph showing the effect of separating the weld and the separation distance h on the web deformation δ when the distance e at which the web deformation was greatest was 200 mm. In test specimens No. 2, 6, and 7, in which steel plates were welded to H-beams with dimensions H-450 × 200 × 3.6 × 6.0, the web deformation δ in test specimen No. 2, where the weld was not separated, significantly exceeded the standard value. In contrast, in test specimen No. 7, where the weld was separated and the distance h between them was 90 mm, the deformation δ was significantly smaller and fell below the standard value. In test specimen No. 6, where the distance h was further increased to 150 mm, the deformation δ was even smaller. Similarly, in test specimens No. 8, 11, and 12, which were H-beams with dimensions H-450×185×4.5×6.0 to which steel plates were welded, the web deformation δ was significantly smaller in test specimen No. 12, where the welds were separated and the distance h between them was 90 mm, compared to test specimen No. 8, where the welds were not separated. This was below the standard value, and the deformation δ was further reduced in test specimen No. 11, where the distance h was further increased to 150 mm. These results show that separating the welds is effective in reducing the deformation δ, and that the deformation δ can be sufficiently reduced by setting the separation distance h of the welds to 0.2 times or more the height H of the H-beam (h / H=0.2 in both test specimens No. 7 and 12). 【0019】 Figure 7 illustrates the relationship between the dimensions of the attachment point between a steel plate welded to an H-beam and other members, and the weld length. Steel plates positioned to intersect the axial direction of the H-beam are, for example, called stiffeners or gusset plates, and other members are often further joined to these steel plates by bolt connections or the like. Specifically, for example, another H-beam, which is a secondary beam, is joined to an H-beam, which is a main beam, via a steel plate that is a stiffener or gusset plate. In such cases, it is preferable that the weld length between the web and the steel plate, i.e., the web height d minus the separation distance h of the weld, is greater than or equal to the height g of the joint between the steel plate and the other member. Generally, when an H-beam is a main beam, other members such as secondary beams that are joined are smaller than the H-beam, so even if the separation distance h of the weld is 0.2 times or more the height H of the H-beam, (dh)≧g is satisfied. On the other hand, since the height g of the joint is often about 0.2 times the height H of the H-shaped steel, it is preferable that the separation distance h of the welded joint be 0.8 times or less the height H of the H-shaped steel. 【0020】 Figure 8 is a graph showing the relationship between the presence or absence of weld separation and the distance e and the amount of web deformation δ. In the case of H-beams with dimensions H-450×200×3.6×6.0 (test specimens No. 1, 2, 5, 6), at a distance e=100mm, both specimen No. 1, where the weld is not separated, and specimen No. 5, where the weld is separated at h=150mm, have small deformation amounts δ and satisfy the standard value. However, specimen No. 5, where the weld is separated, shows an even smaller deformation amount δ. On the other hand, at a distance e=200mm, specimen No. 2, where the weld is not separated, shows a deformation amount δ that significantly exceeds the standard value, while specimen No. 6, where the weld is separated at h=150mm, shows a significantly reduced deformation amount δ that falls below the standard value. In the case of H-beams with dimensions H-450×185×4.5×6.0 (test specimens 8, 9, 11, and 13), the deformation amount δ in test specimen No. 8, where the weld was not separated at a distance e=200mm, significantly exceeded the standard value, whereas in test specimen No. 11, where the weld was separated at h=150mm, the deformation amount δ was greatly reduced and fell below the standard value. Similarly, in test specimen No. 9, where the weld was not separated at a distance e=450mm, the deformation amount δ was smaller than that of No. 8 but still exceeded the standard value, whereas in test specimen No. 13, where the weld was separated at h=150mm, the deformation amount δ was reduced and fell below the standard value. In other words, it can be seen that the deformation suppression effect of separating the weld against web deformation due to thermal distortion of welding can be expected regardless of the distance e. 【0021】 Figure 9 is a graph showing the relationship between the bending stiffness D of the web and the deformation δ of the web. The bending stiffness D of the web is determined by the web thickness t. w It can be expressed by the following equation (1), which includes the following: In equation (1), E is the Young's modulus of the steel forming the web, and v is Poisson's ratio. Since there is a linear correlation between the amount of deformation when an external force is applied to the web in an H-beam and the bending stiffness D, it is presumed that there is also a correlation between the amount of deformation δ of the web due to thermal strain of welding and the bending stiffness D. In the graph of Figure 9, the web plate thickness t w =3.6mm, width thickness ratio d / t w Test specimen No. 2 with approximately 122, and web plate thickness t w =4.5mm, width thickness ratio d / tw The deformation amount δ of specimen No. 8 in ≈97 is shown. In all specimens, the distance e = 200 mm, and the welded joint is not separated. By extrapolating assuming a linear correlation between the web deformation amount δ and the bending stiffness D, the conditions under which the web deformation amount δ falls below the standard value (1 / 150 of the height H) are determined. When the height of the H-beam of the specimen is the same as that of the specimen, H = 450 mm, the web plate thickness t w If only the web plate thickness t is changed, the deformation amount δ is estimated to fall below the standard value based on the bending stiffness D. w =6mm, width thickness ratio d / t w This is the case when =73. In other words, if the welded area is not separated, for example, the web width-to-thickness ratio d / t w When the value exceeds 75, a large deformation amount δ may occur due to thermal distortion during welding with the steel plate, and therefore, in such cases, a configuration that separates the welded portion, as in the embodiment of the present invention, is considered effective. 【0022】 【number】 [Explanation of Symbols] 【0023】 1...Welded structure, 2...H-beam, 21...Flange, 22...Flange, 23...Web, 3...Steel plate, 41,42...Welded joint.

Claims

[Claim 1] An H-shaped steel having an H-shaped cross section including a first flange, a second flange, and a web, wherein the width-to-thickness ratio of the web exceeds 75, A steel plate arranged so as to intersect the material axis direction of the H-shaped steel, The first flange and the first weld formed between the web and the steel plate, A second weld is formed between the second flange and the web and the steel plate, and is separated from the first weld. A welded structure of steel members equipped with the following features. [Claim 2] The welded steel member structure according to claim 1, wherein the thickness of the web is less than 6 mm. [Claim 3] The welded steel member structure according to claim 1, wherein the distance between the first weld and the second weld is 0.2 times or more the height of the H-shaped steel. [Claim 4] 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. [Claim 5] 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 axial direction is 1.5 times or less the height of the H-shaped steel. [Claim 6] A welding method for steel members, 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 the width-to-thickness ratio of the web exceeds 75, and the steel plate being arranged to intersect the material axis direction of the H-shaped steel, A step of welding the first flange and the steel plate, A step of welding the web and the steel plate on the first flange side, A step of welding the web and the steel plate at a position on the second flange side and separate from the first flange side, and The process of welding the second flange and the steel plate. A welding method for steel members including steel members.

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