Welded fabricated H-shaped steel

Abstract

To provide a weld-assembled H-shaped steel allowing shear force of a fillet weld portion formed through fillet weld acting on a web to be securely transmitted and allowing residual deformation of the web to be suppressed within the allowance.SOLUTION: A weld-assemble H-shaped steel 25 is provided with a pair of flanges 26, 27, and webs 28 welded on the pair of flanges through fillet weld portions 29, 30, respectively, wherein a size s of the fillet weld portion is less than a thickness of the web and meets the formula (1).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to Welded fabricated H-shaped steel this.

Background Art

[0002] Conventionally, seismic resistance has not been required for secondary beams in steel frame buildings. For this reason, for secondary beams, rolled H-shaped steel with a larger width-to-thickness ratio of the flange or web is used compared to primary beams. This is because if the width-to-thickness ratio of the web is set large, it is relatively easy to realize a lightweight, high-rigidity, and high-section-efficiency H-shaped steel. In recent years, with the increase in the span (length) of secondary beams, H-shaped steel with a width-to-thickness ratio of the web increased to about 70, which is the manufacturing limit of rolled H-shaped steel, has been used for secondary beams. In this H-shaped steel, the mass-specific rigidity is large and the section efficiency is good. Furthermore, as a method for further increasing the section efficiency of H-shaped steel, a method of increasing the width-to-thickness ratio of the web using welded fabricated H-shaped steel with fewer manufacturing restrictions regarding dimensions can be considered.

[0003] On the other hand, in welded fabricated H-shaped steel with a large width-to-thickness ratio of the web, when welding the intersection line of the flange and the web, after the H-shaped steel is cooled, the web may be deformed so as to bend in the thickness direction of the web. The cause of this web deformation is explained as the following mechanism. First, with the heat input due to welding, the entire H-shaped steel is heated up, and the entire H-shaped steel expands in the length direction (material axis direction) of the member. Next, the central portion in the width direction of the web far from the heat input portion starts to cool earlier than other portions. Subsequently, the flange near the heat input portion and the portion of the web near the flange start to cool. When the portion near the flange of the web, which is cooled later, starts to contract in the length direction of the member, since the central portion in the width direction of the web that was cooled earlier has already finished contracting, the force with which the portion near the flange of the web, which is cooled later, tries to contract in the length direction of the member acts as a compressive force on the central portion in the width direction of the web that was cooled earlier. Due to receiving this compressive force and being originally prone to buckling because of the large width-to-thickness ratio, a buckling waveform such that the web bends occurs as residual deformation.

[0004] These residual deformations reduce the structural properties of the H-shaped steel, the manufacturability during processing of the H-shaped steel in the factory, and the constructability during joining with other members at the construction site. Therefore, it is necessary to avoid the occurrence of these residual deformations or suppress the degree of their occurrence below a certain level. Also, as prior art documents regarding the fillet welding of the flange and the web, for example, in Non-Patent Document 1, it is described that "the size of the fillet welding is less than or equal to the thickness of the thinner base material", or in the case of a plate thickness of 6 mm or less where the width-thickness ratio tends to be large, "the size of the fillet welding should be 1.5 times the plate thickness of the thinner material and 6 mm or less".

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, although these values disclosed in Non-Patent Document 1 are set from the viewpoints of reducing the heat influence on the material of the steel plate and suppressing the residual deformation of the H-shaped steel, they are not values set in full consideration of suppressing the residual deformation of the H-shaped steel with a large width-thickness ratio of the web. Also, if the size of the fillet weld formed by the fillet welding is too small, the shear force acting on the web cannot be transmitted to the flange.

[0007] The present invention has been made in view of such problems, and while ensuring that the fillet weld formed by fillet welding transmits the shear force acting on the web, suppresses the residual deformation of the web below the allowable value Welded fabricated H-shaped steel for the purpose of providing.

Means for Solving the Problems

[0008] To solve the above problems, the present invention proposes the following means. The welded and assembled H-shaped steel of the present invention is a welded and assembled H-shaped steel comprising a pair of flanges and a web joined to each of the pair of flanges by fillet welds, wherein the size s (mm) of the fillet welds is less than the thickness of the web, and the size s satisfies the following formulas (1) and (2). However, τ y,depo is the shear yield strength (N / mm 2 ) of the fillet welds, I is the moment of inertia about the strong axis of the welded and assembled H-shaped steel (mm 4 ), H is the depth (mm) of the welded and assembled H-shaped steel, t f is the thickness (mm) of the flange, W is the width (mm) of the welded and assembled H-shaped steel, τ cr is the elastic shear buckling strength (N / mm 2 ) of the welded and assembled H-shaped steel, A w is the cross-sectional area (mm 2 ) of the web perpendicular to the material axis direction of the welded and assembled H-shaped steel.

[0009]

Equation

[0010] In the present invention, the size s of the fillet welds is a relatively small value less than the thickness of the web, and the heat input when forming the fillet welds by welding is suppressed, so that the residual deformation of the web is suppressed within a predetermined range not exceeding the allowable value. Also, the elastic shear buckling strength τ cr is a value obtained by precisely calculating the strength when a shear force acts on the welded and assembled H-shaped steel and causes buckling, taking into account the combined deformation of the web and the pair of flanges in the welded and assembled H-shaped steel. Therefore, by satisfying formulas (1) and (2), for example, when the welded and assembled H-shaped steel is used as a beam, the size s of the fillet welds, which is precisely calculated, can reliably transmit the shear force acting on the web within a range where the web does not undergo elastic shear buckling. As described above, the fillet weld portion can reliably transmit the shear force acting on the web and suppress the residual deformation of the web of the welded and assembled H-shaped steel to within the allowable value.

[0013] Further, in the welded and assembled H-shaped steel, the width-thickness ratio of the web may be 109 or more. In this invention, it is possible to obtain a welded and assembled H-shaped steel having a relatively high cross-sectional efficiency with a width-thickness ratio of the web of 109 or more.

[0014] Further, in the welded and assembled H-shaped steel, the fillet weld portion may be formed only on one side in the thickness direction of the web with respect to each of the pair of flanges. In this invention, it is possible to easily perform the fillet welding for forming the fillet weld portion and manufacture the welded and assembled H-shaped steel.

Advantages of the Invention

[0017] In the Welded fabricated H-shaped steel present invention, the fillet weld portion formed by fillet welding can reliably transmit the shear force acting on the web and suppress the residual deformation of the web to within the allowable value.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0019] Hereinafter, a building using an embodiment of the welded and assembled H-shaped steel according to the present invention will be described with reference to FIGS. 1 to 9.

[0020] 〔1. Configuration of a Building Using Welded and Assembled H-shaped Steel〕 As shown in FIG. 1, the building 1 includes a plurality of columns 10, a plurality of large beams 15, welded and assembled H-shaped steels 25 which are small beams, a floor slab 35, and the like. In FIG. 1, the floor slab 35 is shown by a two-dot chain line. The welded and assembled H-shaped steel 25 may be a rolled H-shaped steel.

[0021] The columns 10 extend along the vertical direction. The plurality of columns 10 are arranged at intervals from each other. The columns 10 are made of steel frame, RC (Reinforced Concrete), SRC (Steel Reinforced Concrete), CFT (Concrete Filled steel Tube), or the like. For example, the large beam 15 is made of H-shaped steel. The large beam 15 includes a first flange 16 and a second flange 17, and a web 18 connecting the flanges 16 and 17. The second flange 17 is arranged above the first flange 16. A gusset plate (not shown) is joined to the web 18 of the large beam 15 by welding or the like. The large beam 15 spans between adjacent columns 10 and extends in a direction along the horizontal plane. Both ends of the large beam 15 are respectively joined to the columns 10 by welding or the like. Note that the large beam 15 may also be made of RC or SRC.

[0022] As shown in FIGS. 1 and 2, when the web is the welded fabricated H-shaped steel 25, it includes a pair of flanges 26, 27 and a web 28 joined to each of the pair of flanges 26, 27 by fillet welds 29, 30. Hereinafter, one of the pair of flanges 26, 27 may be referred to as the first flange 26, and the other of the pair of flanges 26, 27 may be referred to as the second flange 27. The second flange 27 is disposed above the first flange 26. As shown in FIG. 2, the fillet weld 29 is a weld formed by joining the first flange 26 and the web 28 by fillet welding. Similarly, the fillet weld 30 is a weld formed by joining the second flange 27 and the web 28 by fillet welding.

[0023] The fillet welds 29, 30 are formed only on one side in the thickness direction of the web 28 with respect to each of the flanges 26, 27. That is, the fillet weld 29 is formed by fillet welding the first flange 26 and the web 28 on the first side in the thickness direction of the web 28. The fillet weld 30 is formed by fillet welding the second flange 27 and the web 28 on the first side in the thickness direction of the web 28. Note that the fillet weld 30 may be formed by fillet welding the second flange 27 and the web 28 on the second side opposite to the first side in the thickness direction of the web 28. The width-to-thickness ratio of the web 28 is preferably 109 or more.

[0024] As shown in FIG. 1, the welded fabricated H-shaped steel 25 is spanned between the opposing main girders 15 and extends in a direction along the horizontal plane. Both axial ends of the welded fabricated H-shaped steel 25 in the material axis direction are connected to the gusset plates of the main girders 15 by high-strength bolts (not shown) or the like. Although not shown, the floor slab 35 includes, for example, a deck plate, concrete, reinforcing bars, and shear connectors. The deck plate is formed by bending a steel plate or the like. The deck plate is disposed on the second flange 27 of the welded fabricated H-shaped steel 25. The deck plate and the second flange 27 are joined to each other by a joint such as plug welding. The concrete is formed in a flat plate shape with its thickness direction along the vertical direction. The concrete is disposed on the deck plate.

[0025] The floor slab 35 includes a plurality of reinforcing bars. The first reinforcing bar, which is a part of the plurality of reinforcing bars, extends in the material axis direction of the welded fabricated H-shaped steel 25. The second reinforcing bar, which is the remainder of the plurality of reinforcing bars, extends along a horizontal plane and in a direction orthogonal to the first reinforcing bar. The first reinforcing bar and the second reinforcing bar are embedded in the concrete. The shear connector is, for example, a headed stud. The floor slab 35 includes a plurality of shear connectors. The lower ends of the plurality of shear connectors are fixed to the upper surface of the second flange 27 of the welded fabricated H-shaped steel 25 at intervals in the material axis direction. The shear connectors are embedded in the concrete.

[0026] FIG. 3 shows a photograph of a cross section around the fillet weld portion 29 in the welded fabricated H-shaped steel 25. The size s (mm) of the fillet weld portion 29 is defined in the "Architectural Construction Standard Specifications JASS6 Steel Structure Work", 11th Edition, Revised in 2018, edited by the Japan Institute of Architects, Incorporated Association (hereinafter abbreviated as JASS6). Specifically, as shown in FIG. 4, a right isosceles triangle 29a that contacts the surface of the first flange 26, the surface of the web 28, and the surface of the fillet weld portion 29 is defined. At this time, the size s is the length of the side sandwiching the right angle of the right isosceles triangle 29a. The same applies to welded portions such as the fillet weld portion 30. In addition, in FIG. 4, the throat thickness c and the leg length b of the fillet weld portion 29 are shown.

[0027] In the following, in the welded and assembled H-shaped steel, a study was conducted to reliably transmit the shear force acting on the web at the fillet weld and to suppress the residual deformation of the web below the allowable value. In this study, in the present embodiment, the elastic shear buckling strength (buckling stress) τ of the H-shaped steel when a shear force acts on the H-shaped steel and the H-shaped steel buckles, which is disclosed in Japanese Patent Application Laid-Open No. 2021-6787 (hereinafter referred to as the related prior application), was used. cr (N / mm 2 ) is used. In the following, an outline of the elastic shear buckling strength τ cr will be described.

[0028] [2. Elastic Shear Buckling Strength of H-Shaped Steel] As shown in FIG. 5, the x-axis is defined along the material axis direction of the welded and assembled H-shaped steel 25. It is assumed that the web 28 extends along this x-axis and the y-axis, which is the plate width direction of the web 28. That is, the flanges 26 and 27 are arranged so as to sandwich the web 28 in the y-axis direction. The axis extending in the plate thickness direction of the web 28 is defined as the z-axis. The position of the center of the web 28 in the direction along the y-axis is taken as the origin of the y-axis. The direction from the first flange 26 to the second flange 27 is taken as the positive direction of the y-axis.

[0029] Here, as shown in FIG. 2, the dimensions and the like of the welded and assembled H-shaped steel 25 are defined. The thickness of each of the first flange 26 and the second flange 27 is t f (mm). The width of the welded and assembled H-shaped steel is W (mm). The value of half of the width of each of the first flange 26 and the second flange 27 is b f (mm). At this time, the width W is equal to 2b f . The thickness of the web 28 is t w (mm). The depth of the welded and assembled H-shaped steel 25 is H (mm). The distance between the center of the first flange 26 and the center of the second flange 27 in the direction along the y-axis is b w (mm). The cross-sectional area of the web 28 perpendicular to the material axis direction of the welded and assembled H-shaped steel 25 is A w (mm 2 ).

[0030] Let the Young's modulus of the welded built-up H-shaped steel 25 be E (N / mm 2 ). Let the Poisson's ratio of the welded built-up H-shaped steel 25 be ν (-). Let the shear yield strength of the fillet welds 29 and 30 be τ y,depo (N / mm 2 ). Let the moment of inertia about the strong axis (z-axis) of the welded built-up H-shaped steel 25 be I (mm 4 ). Let the shear yield strength of the welded built-up H-shaped steel be τ y (N / mm 2 ). The shear yield strength τ y is equal to, for example, the value of (F / √3) when the design base strength of the base materials of each of the pair of flanges and the web described later is F. As shown in FIG. 5, it is assumed that a shear force F1 acts in the y-axis direction on the end faces 25a in the x-axis direction of the welded built-up H-shaped steel 25, causing the welded built-up H-shaped steel 25 to buckle. Let the half-wavelength in the direction along the x-axis of the web 28, which is displaced in a wavy pattern alternately in the positive direction and the negative direction of the z-axis as it approaches the first end in the direction along the x-axis of the web 28, be a (mm).

[0031] At this time, the elastic shear buckling strength τ cr is a real number that gives the minimum positive value to the elastic shear buckling strength τ cr according to Equation (12) using Equations (6) to (11), based on a n , b n , λ, and the half-wavelength a.

[0032]

Equation

[0033] However, N is a natural number of 2 or more, and a0, a n , b n , λ are undetermined coefficients. The right side of Equation (11) changes the denominator inside [] corresponding to the infinitesimal elements dx and dz in the right side of Equation (53) of the related prior application. The elastic shear buckling strength τ cris a value that precisely determines the strength when a shear force acts on the welded H-shaped steel 25 causing it to buckle, taking into account the coupled deformation of the web 28 and the pair of flanges 26, 27 in the welded H-shaped steel 25.

[0034] [3. Consideration of the size of the fillet weld that can reliably transmit the shear force acting on the web] As a result of careful investigation, the inventors have found that when the size s of the fillet welds 29, 30 satisfies the formulas (15) to (17), respectively, the fillet welds 29, 30 can reliably transmit the shear force acting on the web 28.

[0035]

number

[0036] Here, in equation (17), A we is the effective cross-sectional area (mm 2 In equation (16), Q Max is the shear force (N) acting on the welded H-shaped steel 25 when it buckles in shear. The value on the right side of equation (15) is the size s of the web 28 required to reliably transmit the shear force acting on the web 28 (ensuring the shear strength of the web 28). req (mm). In equation (16), the cross-sectional area A of the web 28 w Instead, cross-sectional area A w To (τ cr / τ y ) multiplied by the effective cross-sectional area A of the web 28 we By using the above, the range of size s of the fillet welds 29, 30 that can reliably transmit the shear force acting on the web 28 can be accurately calculated using equation (15).

[0037] Equations (16) and (17) can be summarized as equation (18).

[0038]

number

[0039] Note that the shear stress τ generated at the intersection line of the flanges 26, 27 and the web 28 w (N / mm 2 ) is obtained by equation (20).

[0040]

Equation

[0041] 〔4. Experimental Results〕 An experiment was conducted to manufacture a welded fabricated H-shaped steel by fillet-welding a web to each of a pair of flanges. Submerged Arc Welding was used for welding. The welding conditions were based on the requirements of Quality Classification S501-H in JIS Z 3183:2012, Quality Classification of Submerged Arc Weld Metals for Carbon Steel and Low Alloy Steel.

[0042] Welded fabricated H-shaped steels were manufactured under the conditions of Case No. 1 to 4 shown in Table 1.

[0043]

Table 1

[0044] In Case No. 1 to 4, the design base strength F of the base materials of each of the pair of flanges and the web is 295 N / mm 2 . The design base strength of the fillet-welded part is 295 N / mm 2 . For example, in Case No. 1, the cross-sectional shape of the welded fabricated H-shaped steel is 700×175×4.5×9.0. That is, the thickness t w of the web of the welded fabricated H-shaped steel in Case No. 1 is 4.5 mm. The width-to-thickness ratio of the web is 151.6. The length L of the welded fabricated H-shaped steel is 7,000 mm. The heat input during fillet-welding is 4.4 kJ / cm. When the input heat was 4.4 kJ / cm, the current was 330 A, the voltage was 29 V, and the welding speed was 130 cm / min. When the input heat was 2.7 kJ / cm, the current was 280 A, the voltage was 24 V, and the welding speed was 150 cm / min.

[0045] Here, the measurement method of the web deformation e1 by the average of three cross-sections will be described. As shown in Fig. 6, in a certain cross-section of the welded assembly H-shaped steel 25, the deformation e1, which is the deflection in the thickness direction of the web 28 in the web 28, is measured. The cross-section of the welded assembly H-shaped steel for measuring the deformation e1 is as follows. The welded assembly H-shaped steel is divided into four equal parts in the material axis direction and divided into the first part to the fourth part. The deformation e1 is measured at three cross-sections: the cross-section at the boundary between the first part and the second part, the cross-section at the boundary between the second part and the third part, and the cross-section at the boundary between the third part and the fourth part. The average value of the three measured deformations e1 is obtained and taken as the average of the three cross-sections.

[0046] A photograph of the welded assembly H-shaped steel of Case No. 1 is shown in Fig. 7. It can be seen that in the welded assembly H-shaped steel, a deformation that bends in the thickness direction of the web has occurred. A photograph of the welded assembly H-shaped steel of Case No. 4 is shown in Fig. 8. It can be seen that in the welded assembly H-shaped steel, the deformation of the web is suppressed.

[0047] A part of the experimental results is shown in Table 1. In the welded assembly H-shaped steel of Case No. 1, the deformation e1 of the average of three cross-sections was 6.7 mm. In JASS6, the limit tolerance △e1 of the web deformation is defined as the smaller of the value obtained by dividing the H of the welded assembly H-shaped steel by 100 and 6 mm. Therefore, the limit tolerance △e1 in Case No. 1 is 6.0 mm. The ratio (e1 / △e1) is 1.11 from the formula (6.7 / 6.0). In the welded assembly H-shaped steels of Case No. 1, 2, and 4, weld beads were formed to form fillet weld joints, and the web was joined to each of the pair of flanges by the fillet weld joints. On the other hand, in the welded and assembled H-shaped steel of Case No. 3, no weld bead was formed, and the web was not joined to each of the pair of flanges.

[0048] The remainder of the experimental results is shown in Table 2.

[0049]

Table 2

[0050] In the welded and assembled H-shaped steel of Case No. 1, at each fillet weld, the size s was 4.6 mm. The throat thickness c was 3.3 mm. The size s req was 1.9 mm. In Case No. 3, the value of the size s could not be obtained and the relationship s≧s req was not satisfied, but in Cases No. 1, 2, and 4, it was found that the relationship s≧s req was satisfied. When the relationship s≧s req is satisfied, that is, when the formula (15) is satisfied, the fillet weld can surely transmit the shearing force acting on the web.

[0051] Also, when the size s of the fillet weld is less than the thickness t w of the web (t w >s) in the case of Case No. 4, it was found that the heat input amount when forming the fillet weld by welding is suppressed, and the residual deformation of the web can be suppressed to be equal to or less than the allowable value, which is the limit tolerance of JASS6, for example.

[0052] The problem of the present embodiment is to provide a welded and assembled H-shaped steel in which the fillet weld formed by the fillet welding surely transmits the shearing force acting on the web and suppresses the residual deformation of the web to be equal to or less than the allowable value. Case No. 4 in which the size s satisfies the formula (t w >s≧s req ) becomes an example, and it was found that Cases No. 1 to 3 in which the size s does not satisfy the formula (t w >s≧s req ) become comparative examples.

[0053] Here, regarding the results of Case Nos. 1 to 4 shown in Tables 1 and 2, the relationship between the heat input and the ratio (e1 / Δe1) of the amount of web deformation during welding to the allowable tolerance of the web is shown in FIG. 9. In FIG. 9, the horizontal axis (x-axis) represents the heat input (kJ / cm), and the vertical axis (y-axis) represents the ratio (e1 / Δe1) (-). Case Nos. 1 and 4 with a cross-sectional shape of 700×175×4.5×9.0 are indicated by solid-line circles. Case No. 2 with a cross-sectional shape of 500×150×4.5×4.5 is indicated by solid-line squares. For Case Nos. 1 and 4 (heat inputs of 2.7 and 4.4 kJ / cm), approximation was performed using a power function (exponential function) passing through the origin. As a result of the approximation, the expression (20) shown by curve L1 was obtained. y = 0.012x 3.0545 ··(20)

[0054] For Case No. 2, approximation was performed using a power function with the same exponent as the expression (20) and passing through the origin. As a result of the approximation, the expression (21) shown by curve L2 was obtained. y = 0.0274x 3.0545 ··(21) In the expression (20), when the value of y becomes 1.0 (when the web deformation e1 becomes equal to the allowable tolerance Δe1), the value of x (heat input) was 4.3 kJ / cm. In the expression (21), when the value of y becomes 1.0, the value of x was 3.2 kJ / cm.

[0055] That is, in the case of the above two types of cross-sectional shapes, if the heat input is 3.2 kJ / cm or less, the web deformation e1 becomes equal to or less than the allowable tolerance Δe1. Here, the method for manufacturing the welded and assembled H-shaped steel of the present embodiment will be described. In the method for manufacturing a welded and assembled H-shaped steel, the web 28 is joined to each of the pair of flanges 26 and 27 by fillet welding to manufacture the welded and assembled H-shaped steel 25. In the method for manufacturing a welded and assembled H-shaped steel, it is preferable that the heat input in each fillet welding is 2.3 kJ / cm or more and 3.2 kJ / cm or less. In the method for manufacturing a welded assembled H-shaped steel, for example, when forming fillet weld portions 29 on both sides in the thickness direction of the web 28 with respect to the first flange 26, the two fillet weld portions 29 may be formed simultaneously. In this case, it is preferable that the heat input amount in the entire two fillet weld portions 29 is 2.3 kJ / cm or more and 3.2 kJ / cm or less. The same applies to the fillet weld portion 30.

[0056] As described above, in the welded assembled H-shaped steel 25 of the present embodiment, the size s of the fillet weld portions 29 and 30 is w less than the thickness t of the web 28, which is a relatively small value. When the fillet weld portions 29 and 30 are formed by welding, the heat input amount is suppressed, and the residual deformation of the web 28 is suppressed within a predetermined range that is equal to or less than the allowable value. Also, the elastic shear buckling strength τ cr is a value obtained by precisely calculating the strength when a shear force acts on the welded assembled H-shaped steel 25 and causes buckling, considering the combined deformation of the web 28 and the pair of flanges 26 and 27 in the welded assembled H-shaped steel 25. Therefore, by satisfying the equations from (15) to (17), when the welded assembled H-shaped steel 25 is used as a joist, the size s of the fillet weld portions 29 and 30, which can reliably transmit the shear force acting as the compressive force to the central portion in the width direction of the web 28, is precisely obtained. As described above, the fillet weld portions 29 and 30 can reliably transmit the shear force acting on the web 28, and the residual deformation of the web 28 of the welded assembled H-shaped steel 25 can be suppressed to be equal to or less than the allowable value.

[0057] When the width-thickness ratio of the web 28 is 109 or more, it is possible to obtain a welded assembled H-shaped steel 25 having a relatively high cross-sectional efficiency with a width-thickness ratio of the web 28 of 109 or more. The fillet weld portions 29 and 30 are formed only on one side in the thickness direction of the web 28 with respect to each of the flanges 26 and 27. For this reason, the fillet welding for forming the fillet weld portions 29 and 30 can be easily performed, and the welded assembled H-shaped steel 25 can be manufactured.

[0058] In addition, in the method for manufacturing the welded and assembled H-shaped steel of the present embodiment, as a result of intensive studies by the inventors, when the heat input in each fillet weld is 2.3 kJ / cm or more, the beads of the fillet weld portions 29 and 30 are surely formed by the fillet weld, and it has been found that the fillet weld portions 29 and 30 surely transmit the shear force acting on the web 28. Further, when the heat input in each fillet weld is 3.2 kJ / cm or less, it has been found that the heat input during fillet welding is suppressed, and the residual deformation of the web 28 is suppressed within a predetermined range that is equal to or less than the allowable value, which is the limit allowable tolerance of JASS6, for example. Therefore, the fillet weld portions 29 and 30 formed by fillet welding can surely transmit the shear force acting on the web 28 and suppress the residual deformation of the web 28 to be equal to or less than the allowable value. When joining the web 28 to each of the pair of flanges 26 and 27 by fillet welding, the size s and the heat input of the fillet weld portions 29 and 30 can be appropriately adjusted.

[0059] 〔5. Size of Fillet Weld Portion Required to Surely Transmit Shear Force Acting on Web〕 The size of the fillet weld portion required to surely transmit the shear force acting on the web was calculated. The results of the calculation are shown in Tables 3 and 4.

[0060]

Table 3

[0061]

Table 4

[0062] For example, the case where the cross-sectional shape is 500×150×4.5×4.5 will be described. In this case, the second moment of area I of the welded and assembled H-shaped steel 25 is 1.27E+08 (1.27×10 8 ) mm 4 . The cross-sectional area A w of the web 28 is 2,210 mm 2 . The shear yield strength τ yis 170 N / mm 2 According to equations (6) to (12), the elastic shear buckling strength τ of the welded and assembled H-shaped steel 25 cr is 94 N / mm 2 . According to equation (17), the effective cross-sectional area A of the web 28 we is 1,219 mm 2 . The design reference strength F of the base materials of each of the pair of flanges and the web is 295 N / mm 2 . The design reference strength F of the fillet weld is 295 N / mm 2 . The shear yield strength τ of the fillet welds 29, 30 y,depo is 170 N / mm 2 .

[0063] According to equation (16), the shear force Q of the welded and assembled H-shaped steel 25 Max is 376.3 kN. According to equation (20), the (maximum) shear stress τ of the fillet weld 29 w is 110 N / mm 2 . The shear stress per unit shear force Q of the fillet weld 29 Max (τ w / Q Max ) is 2.92E-04 (1 / mm 2 ). In the fillet weld 29, the shear force Q acting per unit length in the material axis direction of the welded and assembled H-shaped steel (H-shaped steel member) 25 w,req is 495 N / mm 2 . Note that the shear force Q w,req is obtained by multiplying the (maximum) shear stress τ w by the thickness t of the web 28 w .

[0064] For this welded and assembled H-shaped steel with a cross-sectional shape of 500×150×4.5×4.5, trial calculations were performed by changing the size s of the fillet weld to 2.2 mm, 2.3 mm, and 2.4 mm. For example, when the size s was 2.2 mm, the throat thickness c was 1.5 mm. In the fillet weld 29, the shear resistance Q per unit length in the material axis direction of the welded and assembled H-shaped steel 25 wis 262.3 N / mm. The shear strength Q w is obtained by multiplying the shear yield strength τ y,depo of the fillet weld 29 by the throat thickness c of the fillet weld 29. (Q w,req / Q w ) is less than or equal to 1 (shearing force Q w,req is less than or equal to the shear strength Q w ), the shearing force acting on the web can be reliably transmitted. Therefore, it can be determined that the shearing force acting on the web can be reliably transmitted by the value of the test value (Q w,req / Q w ) being less than or equal to 1. The test value (Q w,req / Q w ) in this case is 1.041, indicating that the shearing force acting on the web cannot be reliably transmitted.

[0065] For the welded built-up H-section steel with a cross-sectional shape of 500×150×4.5×4.5, it was found that the minimum size s for the test value to be less than or equal to 1 is 2.3 mm. On the other hand, for the welded built-up H-section steel with a cross-sectional shape of 700×175×4.5×9.0, it was found that the minimum size s for the test value to be less than or equal to 1 is 1.9 mm.

[0066] [[6. Ratio of the required size of the fillet weld to the thickness of the web]] The above ratio is examined using the ratio of the size s of the fillet welds 29 and 30 to the thickness t w of the web 28 (s / t w . Hereinafter, referred to as the size-thickness ratio). The upper limit value of the size s of the fillet welds 29 and 30 required to suppress the residual deformation of the web 28 below the allowable value (deformation suppression) is obtained as shown in the following equation (24) for the size-thickness ratio, since the size s of the fillet welds 29 and 30 is less than the thickness t w of the web as described above. ·s / t w = 4.5 / 4.5 = 1.0 ··(24)

[0067] In order to reliably transmit the shear force exerted by the fillet welds 29 and 30 on the web 28 (ensuring the shear force of the web), the lower limit of the size s (size-thickness ratio) of the fillet welds 29 and 30 is determined according to the cross-sectional shape of the welded fabricated H-shaped steel 25 as shown in equations (25) and (26) based on the results of [5]. · When the cross-sectional shape is 700×175×4.5×9.0, s / t w =1.9 / 4.5 = 0.42 ··(25) · When the cross-sectional shape is 500×150×4.5×4.5, s / t w =2.3 / 4.5 = 0.51 ··(26)

[0068] That is, for the plurality of cross-sectional shapes, it was found that if the size-thickness ratio is 0.51 or more and less than 1.0, the desired requirements for the residual deformation and shear force are satisfied.

[0069] In the welded fabricated H-shaped steel 25 of this embodiment, as a result of intensive studies by the inventors, it was found that when the size-thickness ratio is 0.51 or more, the beads of the fillet welds 29 and 30 are reliably formed, and the fillet welds 29 and 30 reliably transmit the shear force exerted on the web 28. Also, when the size-thickness ratio is less than 1.0, it was found that the heat input amount when forming the fillet welds 29 and 30 by welding can be suppressed within a predetermined range where the residual deformation of the web 28 is within the allowable value. Therefore, in the welded fabricated H-shaped steel, by setting the size-thickness ratio to 0.51 or more and less than 1.0, the fillet welds 29 and 30 can reliably transmit the shear force exerted on the web 28, and the residual deformation of the web 28 of the welded fabricated H-shaped steel can be suppressed below the allowable value.

[0070] As described above, one embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and modifications, combinations, deletions, etc. of the configuration within the scope not departing from the gist of the present invention are also included. For example, in the above embodiment, the fillet weld portion 29 may be formed on both sides of the web 28 in the thickness direction with respect to the first flange 26. Further, the fillet weld portion 30 may be formed on both sides of the web 28 in the thickness direction with respect to the second flange 27. In the welded and assembled H-shaped steel 25, the width-thickness ratio of the web 28 may be less than 109. The welded and assembled H-shaped steel may be used as a girder.

Description of Reference Numerals

[0071] 25 Welded and assembled H-shaped steel 26 Flange (first flange) 27 Flange (second flange) 28 Web 29, 30 Fillet weld portion

Claims

1. A pair of flanges, and webs joined to each of the pair of flanges by fillet welds, wherein the welded fabricated H-shaped steel comprises: the size s (mm) of the fillet weld is less than the thickness of the web, and the size s satisfies formulas (1) and (2). The welded fabricated H-shaped steel. However, τ ｙ，ｄｅｐｏ is the shear yield strength of the fillet weld (N / mm ２ ), I is the second moment of area about the strong axis of the welded built-up H-section steel (mm ４ ), H is the depth of the welded built-up H-section steel (mm), t ｆ is the thickness of the flange (mm), W is the width of the welded built-up H-section steel (mm), τ ｃｒ is the elastic shear buckling strength of the welded built-up H-section steel (N / mm ２ ), A ｗ is the cross-sectional area perpendicular to the material axis direction of the welded built-up H-section steel in the web (mm ２ ). 【Number 1】

2. The welded fabricated H-shaped steel according to Claim 1, wherein the width-to-thickness ratio of the web is 109 or more.

3. The welded fabricated H-shaped steel according to Claim 1 or 2, wherein the fillet weld is formed only on one side in the thickness direction of the web with respect to each of the pair of flanges.

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