Elastic buckling stress evaluation method, elastic buckling stress evaluation program, lip groove cross-section member manufacturing method, and support structure

Abstract

To provide a method for evaluating elastic buckling stress intensity of a lip-groove cross-sectional member when a bending moment acts on the lip-groove cross-sectional member in which only one flange subjected to tensile force is restrained.SOLUTION: In a lip-groove sectional member 10A having a web 11A, a pair of flanges 12A, 13A provided at both ends of the web in the width direction so as to extend in the thickness direction of the web, and a pair of lips 14A, 15A extending from tips from which the pair of flanges extend so as to approach each other, a first flange, which is one of the pair of flanges, is restrained from deformation in the thickness direction and from rotation about the material axis O1 of the lip-groove sectional member, and elastic buckling stress intensity of the lip-groove sectional member in which a bending moment about the strong axis of the lip-groove sectional member is subjected to the lip-groove section member to pull the first flange is evaluated.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating elastic buckling stress, a program for evaluating elastic buckling stress, a method for manufacturing a lip groove cross-section member, and a support structure. [Background technology]

[0002] Conventionally, lip channel steel (lip channel cross-section member) has been widely used as a base for exterior walls (plate-shaped members) such as furring strips. Lip channel steel is used by attaching the first flange, one of a pair of flanges, to the exterior wall. When a negative pressure load acts on the outer wall, in a lip channel steel, the first flange, which is subjected to tensile force, is restrained by the outer wall, while the other of the pair, the second flange, is subjected to compressive force and is not restrained by anything.

[0003] Figure 17 shows the change in elastic buckling strength relative to the buckling half wavelength when a bending moment acts on a lip channel steel in which only the first flange that receives a tensile force is restrained (hereinafter referred to as a restrained lip channel steel). In Figure 17, the horizontal axis represents the buckling half wavelength (mm), which is half the buckling wavelength, and the vertical axis represents the elastic buckling strength (N / mm 2 ) The solid line L1 represents a restrained lip channel. The dotted line L2 represents a lip channel in which both flanges are not restrained (hereinafter referred to as an unrestrained lip channel). In the restrained lip channel steel, buckling occurs with a buckling wavelength longer than distortional buckling (see region R1 shown in FIG. 17) (hereinafter referred to as elastic buckling (see region R2 shown in FIG. 17)).

[0004] Even if the buckling wavelength becomes longer when the restraining lip channel steel is elastically buckling, the elastic buckling strength of the restraining lip channel steel will not fall below the stress level at which elastic buckling occurs (hereinafter referred to as the elastic buckling stress level). Generally, lip channel steel is used when the length of the buckling half wavelength is in region R3 in FIG. On the other hand, elastic buckling does not occur in the unconstrained lip channel steel, and in region R3, the elastic buckling strength decreases as the buckling wavelength increases.

[0005] The elastic buckling stress of a restrained lip channel is greater than the stress at which lateral buckling strength occurs in an unrestrained lip channel. In other words, in region R3, the elastic buckling stress of a restrained lip channel should be greater than the elastic buckling strength of an unrestrained lip channel. Non-Patent Document 1 discloses a method for evaluating the elastic buckling stress related to lateral buckling. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Japan Iron and Steel Federation, "Guide to the Design of Lightweight Steel Buildings," Gihodo Publishing Co., Ltd., March 2014 Summary of the Invention [Problem to be solved by the invention]

[0007] However, a method for evaluating the elastic buckling stress of restrained lip channel steel that takes into account the restraint effect has not yet been established. Currently, performance evaluation using eigenvalue analysis or a design that ignores the restraint effect is required.

[0008] The present invention has been made in consideration of these problems, and aims to provide a method and program for evaluating the elastic buckling stress of a lip grooved cross-section member when a bending moment acts on the lip grooved cross-section member in which only one flange receiving a tensile force is restrained, and a support structure that effectively increases the allowable stress of a lip grooved cross-section member when the yield strength of the lip grooved cross-section member is increased when a bending moment acts on the lip grooved cross-section member in which only one flange receiving a tensile force is restrained. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention proposes the following means. (1) Aspect 1 of the present invention is a lip groove section member having a web, a pair of flanges provided at both ends of the web in the width direction so as to extend in the thickness direction of the web, and a pair of lips extending toward each other from the tip ends of the pair of flanges, wherein a first flange, which is one of the pair of flanges, is constrained from deformation in the thickness direction of the web and from rotation about the material axis of the lip groove section member, and a bending moment acts on the lip groove section member about its strong axis, causing the first flange to be pulled. A method for evaluating the elastic buckling stress of the lip groove section member is provided, the method comprising: a calculated elastic buckling stress σ calculated by equation (1): crcal The method for evaluating elastic buckling stress includes performing an evaluation step of evaluating the elastic buckling stress using the above-mentioned formula. where E is the Young's modulus of the lip groove cross section member (N / mm 2 ), h is the width of the web (mm), b is the width of each of the pair of flanges (mm), c is the width of each of the pair of lips (mm), t is the thickness of each of the web, the pair of flanges, and the pair of lips (mm), and f() is a function of the variables in ().

[0010]

number

[0011] In this invention, the inventors have conducted extensive research and have found that the elastic buckling stress of a lip groove cross section member when a bending moment acts and the first flange is pulled is (σ crcal It was found that the elastic buckling stress of a lip grooved section member is a function of four variables, (t / h), (b / h), (c / b), and (t / (h+2b+2c)), as shown in (1). Therefore, equation (1) can be used to evaluate the elastic buckling stress of a lip grooved section member when a bending moment acts on the member and only one flange of the member is restrained and subjected to a tensile force.

[0012] (2) A second aspect of the present invention may be the method for evaluating an elastic buckling stress according to (1), wherein the function f( ) is determined by equation (2). Here, α1, α2, α3, and α4 are dimensionless constants.

[0013]

number

[0014] In this invention, the calculated elastic buckling stress σ is calculated using equation (2) in which the function f() in equation (1) is specifically defined using constants α1 to α4. crcal can be calculated more precisely.

[0015] (3) A third aspect of the present invention may be the method for evaluating an elastic buckling stress according to (2), in which the constant α1 satisfies the formula (3). 0.108≦α1≦0.117 (3) In this invention, the calculated elastic buckling stress σ crcal can be evaluated on the safe side to a certain extent.

[0016] (4) A fourth aspect of the present invention may be the method for evaluating an elastic buckling stress according to (2) or (3), in which the constant α2 satisfies the formula (4). 0.129≦α2≦0.211 (4) In this invention, the deviation from the true value of the elastic buckling stress is suppressed with respect to the constant α2, and the calculated elastic buckling stress σ crcal can be obtained.

[0017] (5) A fifth aspect of the present invention may be the method for evaluating an elastic buckling stress according to any one of (2) to (4), in which the constant α3 satisfies the formula (5). 0.0624≦α3≦0.729 (5) In this invention, the deviation from the true value of the elastic buckling stress is suppressed with respect to the constant α3, and the calculated elastic buckling stress σ crcal can be obtained.

[0018] (6) A sixth aspect of the present invention may be the method for evaluating an elastic buckling stress according to any one of (2) to (5), in which the constant α4 satisfies the formula (6). 8.14≦α4≦8.32 (6) In this invention, the deviation from the true value of the elastic buckling stress is suppressed with respect to the constant α4, and the calculated elastic buckling stress σ crcal can be obtained.

[0019] (7) Aspect 7 of the present invention is a method for manufacturing a lip grooved cross-section member, which manufactures the lip grooved cross-section member whose elastic buckling stress has been evaluated using any of the elastic buckling stress evaluation methods (1) to (6). This invention allows the manufacture of lip grooved section members whose elastic buckling stress has been evaluated when a bending moment acts on a lip grooved section member in which only one flange that is subjected to tensile force is restrained.

[0020] (8) Aspect 8 of the present invention is a lip groove section member having a web, a pair of flanges provided at both ends of the web in the width direction so as to extend in the thickness direction of the web, and a pair of lips extending toward each other from the tip ends of the pair of flanges, wherein a first flange, which is one of the pair of flanges, is constrained from deformation in the thickness direction of the web and from rotation about the material axis of the lip groove section member, and a bending moment acts on the lip groove section member about its strong axis, pulling the first flange, and the lip groove section member is configured to perform an elastic buckling stress evaluation program for an evaluation device that evaluates the elastic buckling stress of the lip groove section member, the program being configured to operate the evaluation device to calculate the calculated elastic buckling stress σ calculated by equation (7): crcal The elastic buckling stress evaluation program functions as an evaluation unit that evaluates the elastic buckling stress using the above program. where E is the Young's modulus of the lip groove cross section member (N / mm 2), h is the width of the web (mm), b is the width of each of the pair of flanges (mm), c is the width of each of the pair of lips (mm), t is the thickness of each of the web, the pair of flanges, and the pair of lips (mm), and f() is a function of the variables in ().

[0021]

number

[0022] In this invention, the inventors have conducted extensive research and have found that the elastic buckling stress of a lip groove cross section member when a bending moment acts and the first flange is pulled is (σ crcal It was found that the elastic buckling stress of a lip grooved section member is a function of four variables, (t / h), (b / h), (c / b), and (t / (h+2b+2c)), as shown in (7). Therefore, equation (7) can be used to evaluate the elastic buckling stress of a lip grooved section member when a bending moment acts on the member and only one flange is restrained and subjected to a tensile force.

[0023] (9) Aspect 9 of the present invention is a support structure comprising a lip groove cross-section member and a plate-like member attached to the lip groove cross-section member, wherein the lip groove cross-section member has a web, a pair of flanges at both widthwise ends of the web so as to extend in the thickness direction of the web, and a pair of lips extending toward each other from the tip ends of the pair of flanges, and the plate-like member is attached to a first flange, which is one of the pair of flanges, and restrains deformation of the first flange in the thickness direction of the web and restrains rotation of the lip groove cross-section member about the material axis, and a bending moment acts on the lip groove cross-section member about the strong axis of the lip groove cross-section member, pulling the first flange, thereby satisfying equations (8) to (13). where h is the width of the web (mm), b is the width of each of the pair of flanges (mm), c is the width of each of the pair of lips (mm), t is the thickness of each of the web, the pair of flanges, and the pair of lips (mm), and F is the yield strength of the lip groove cross-section member (N / mm 2 )

[0024]

number

[0025] In this invention, when a bending moment acts on a lip grooved section member in which only one flange that is subjected to a tensile force is restrained, the allowable stress of the lip grooved section member can be effectively increased by increasing the yield strength of the lip grooved section member. [Effects of the Invention]

[0026] The elastic buckling stress evaluation method and program of the present invention can evaluate the elastic buckling stress of a lip grooved section member when a bending moment acts on the lip grooved section member with only one flange restrained and receiving a tensile force. Furthermore, the support structure of the present invention can effectively increase the allowable stress of a lip grooved section member by increasing the yield strength of the lip grooved section member when a bending moment acts on the lip grooved section member with only one flange restrained and receiving a tensile force. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a cross-sectional view showing the general configuration of a building in which a support structure according to one embodiment of the present invention is used. [Figure 2] FIG. 2 is a perspective view of a first lip channel steel of the support structure. [Figure 3] FIG. 10 is a diagram illustrating the strong axis and weak axis of the first lip channel steel. [Figure 4] FIG. 10 is a perspective view of a support structure in a first modified example of an embodiment of the present invention. [Figure 5]4 is a schematic diagram illustrating negative pressure and bending moment acting on the first lip channel steel. FIG. [Figure 6] FIG. 2 is a perspective view of an analytical model of the first lip channel steel. [Figure 7] FIG. 10 is a graph showing the change in (σcr / E) relative to (σcrcal / E) before adjusting the coefficient of variation. [Figure 8] This is a graph showing the change in (σcr / E) with respect to (t / h). [Figure 9] This is a graph showing the change in (σcr / E) with respect to (b / h). [Figure 10] This is a graph showing the change in (σcr / E) with respect to (c / b). [Figure 11] FIG. 10 is a graph showing the change in correlation coefficient R with respect to (t / (h+2b+2c)). [Figure 12] FIG. 10 shows the change in (σcr / E) relative to (σcrcal / E) after adjusting for the coefficient of variation. [Figure 13] This is a graph showing the change in (fb_500 / fb_345) with respect to the dimensionless quantity K. [Figure 14] FIG. 2 is a diagram showing an outline of an elastic buckling stress evaluation device that can preferably perform the elastic buckling stress evaluation method. [Figure 15] 1 is a flowchart showing a method for evaluating an elastic buckling stress in one embodiment of the present invention. [Figure 16] A cross-sectional view showing the general configuration of another building in which a support structure of one embodiment of the present invention is used. [Figure 17] FIG. 10 is a diagram showing the change in elastic buckling strength relative to the buckling half wavelength. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of the elastic buckling stress evaluation method, elastic buckling stress evaluation program, lip groove cross section member manufacturing method, and support structure according to the present invention will be described with reference to Figures 1 to 16.

[0029] [1. Support structure configuration] As shown in FIG. 1, a support structure 40A of this embodiment is used in a building 1. For example, the building 1 is a multi-story structure having one or more floors (story). Note that FIG. 1 illustrates a two-story building. The building 1 includes a first lip channel steel (lip channel section member) 10A, a first lip channel steel 10B, a second lip channel steel (lip channel section member) 10C, a second lip channel steel 10D, plate-like members 20A and 20B, a plurality of connecting members 25 (see FIG. 2), a floor 30, and plate-like members 35A and 35B.

[0030] In this embodiment, the configuration of the first lip channel steel 10A is identical to that of the lip channel steels 10B, 10C, and 10D. Therefore, the configuration of the first lip channel steel 10A is indicated by adding the capital letter "A" to the numeral or numeral and lowercase alphabetical character of the symbol. The configuration of the lip channel steels 10B, 10C, and 10D corresponding to the first lip channel steel 10A is indicated by adding the capital letters "B," "C," and "D" to the numeral or numeral and lowercase alphabetical character of the first lip channel steel 10A. This avoids redundant explanation. For example, the first flange 12A of the first lip channel steel 10A (described later) and the first flange 12B of the first lip channel steel 10B have the same configuration. The first lip channel steel 10A, the plate-shaped member 20A, and the connecting member 25 constitute a support structure 40A. The second lip channel steel 10D, the plate-shaped member 35A, and the connecting member 25 constitute a support structure 41A.

[0031] For example, the first lip channel steels 10A and 10B extend in the vertical direction. Although not shown, a plurality of pillars and a plurality of beams are provided on a support surface F1 such as the ground via a foundation. The foundation is cast on the support surface F1. A plurality of pillars extend upward from the foundation. A plurality of beams are installed between the pillars. Eaves beams, rafters, etc. (not shown) are fixed to the pillars and beams. In this example, the first lip channel steels 10A, 10B extend in the vertical direction and are fixed to beams or the like. The first lip channel steels 10A, 10B are arranged so as to be spaced apart from each other along a horizontal plane. The first lip channel steels 10A, 10B function as vertical furring strips. For example, the first lip channel steel 10A is a lip channel steel defined in JIS G 3350:2017 Light-duty channel steel (hereinafter referred to as JIS G 3350). As shown in Fig. 2, the first lip channel steel 10A has a web 11A, a first flange (flange) 12A, a second flange (flange) 13A, a first lip (lip) 14A, and a second lip (lip) 15A. In Fig. 2, the plate-shaped member 20A is indicated by a two-dot chain line.

[0032] The web 11A, the flanges 12A and 13A, and the lips 14A and 15A are each formed in the shape of a flat plate by bending a steel plate. The flanges 12A and 13A are provided at both ends of the web 11A in the width direction X so as to extend to a first side Y1 (hereinafter simply referred to as the first side Y1) in the thickness direction Y of the web 11A. Hereinafter, the side in the thickness direction Y opposite to the first side Y1 will be referred to as the second side Y2. The flanges 12A and 13A face each other. The first flange 12A is one of the flanges 12A and 13A. The axial direction (material axis direction) Z, which is a direction along the material axis (axis line, material axis) O1 of the first lip channel steel 10A, is perpendicular to the width direction X and the thickness direction Y. In other words, the width direction X is a direction perpendicular to the axial direction Z and the thickness direction Y.

[0033] The lips 14A and 15A extend toward each other from the leading ends of the flanges 12A and 13A. That is, the first lip 14A extends along the web 11A (along the width direction X) from the leading end of the first flange 12A toward the leading end of the second flange 13A. The second lip 15A extends along the web 11A from the leading end of the second flange 13A toward the leading end of the first flange 12A. A gap is formed between the first lip 14A and the second lip 15A.

[0034] As shown in Fig. 3, in the first lip channel steel 10A, the axis along the thickness direction Y is the strong axis O3, and the axis along the width direction X is the weak axis O4.

[0035] The first lip channel steel 10B is configured similarly to the first lip channel steel 10A. The first lip channel steel 10B has a web, a first flange 12B (see FIG. 1), a second flange, a first lip, and a second lip, which are configured similarly to the web 11A, a first flange 12A, a second flange 13A, a first lip 14A, and a second lip 15A of the first lip channel steel 10A. The first lip channel steels 10A and 10B are shaped steel members each having one web, two flanges, and two lips. The cross-sectional shape of the first lip channel steel is not limited to the specifications of JIS G 3350, and the first lip channel steel may be a lip channel cross-sectional member having a cross-sectional specification not specified in JIS G 3350.

[0036] In plan view, first ends of the second lip channel steels 10C and 10D are joined to each other between the first lip channel steels 10A and 10B. The second lip channel steels 10C, 10D are gradually sloped downward and away from each other toward their second ends opposite the first ends. The second end of the second lip channel steel 10C extends beyond the first lip channel steel 10A to the outside of the lip channels 10A, 10B. The second end of the second lip channel steel 10D extends beyond the first lip channel steel 10B to the outside of the lip channels 10A, 10B. The second lip channel steels 10C and 10D are fixed to a plurality of columns and a plurality of beams via members such as eaves beams and rafters, and connecting metal fittings.

[0037] For example, the plate-shaped members 20A and 20B are exterior walls, and in this example, they are structural plywood. The plate-shaped member 20A is arranged so that its thickness direction is along a horizontal plane. The same applies to the plate-shaped member 20B. The plate-like member may have a plate shape as a whole and may have a shape that displaces in a wave-like manner in the thickness direction of the plate-like member. The plate-like member may be made of gypsum board, wood cement board (a material made by mixing wood raw materials such as wood chips with cement and compressing it into a plate), steel folded plate, a sandwich panel made of resin sandwiched between steel plates, Cross Laminated Timber (CLT), particle board, concrete plate, etc.

[0038] For example, plate-shaped members 35A and 35B are roof facing materials, and in this example, they are structural plywood. Plate-shaped member 35A is arranged so that its thickness direction coincides with the thickness direction of first flange 12C of second lip channel steel 10C. Plate-shaped member 35B is similar to plate-shaped member 35A.

[0039] As shown in Fig. 1, the plate-shaped member 20A is disposed outside the first lip channel steel 10A, 10B and is fixed to the first lip channel steel 10A. More specifically, as shown in Fig. 2, the plate-shaped member 20A is joined to the first flange 12A of the first lip channel steel 10A by a plurality of joining members 25. This example shows a case where one plate-shaped member 20A is joined to the first flange 12A of the first lip channel steel 10A. The intervals between the connecting members 25 may be wider or narrower than the state shown in Fig. 2. For example, if the width of the web 11A of the illustrated first lip channel steel 10A (width h in Fig. 3, which will be described later) is 100 mm, the intervals between the connecting members 25 may be about 300 mm. The plate-like member does not necessarily have to be a single member, and for example, a plurality of members may be stacked in the thickness direction of the plate-like member, or a plurality of plate-like members may be combined to form a large plate-like member.

[0040] The joining members 25 are dry joining members, such as drill screws, nails, bolts, rivets, caulking, etc. The joining members 25 are arranged side by side in the axial direction Z at intervals. By joining the first flange 12A to the plate-like member 20A with a plurality of joining members 25, the first flange 12A is restrained from deformation in the thickness direction Y of the web 11A and from rotation about the material axis O1. In other words, the plate-like member 20A restrains the deformation of the first flange 12A in the thickness direction Y and also restrains the rotation of the first lip channel steel 10A about the material axis O1. The thickness direction Y of the web 11A is the in-plane direction of the first flange 12A. In FIG. 2, the position at which the deformation of the first flange 12A in the thickness direction Y of the web is restrained by the plurality of joining members 25 is indicated by a dashed line L6. In Figure 2, the joining members 25 are aligned in the material axis direction and arranged in a single row in the plate width direction of the first flange 12A (i.e., the thickness direction Y of the web 11A), but the joining members 25 may be arranged in two or more rows, and the joining position may be other than the center of the plate width direction (thickness direction Y) of the first flange 12A.

[0041] 4, the plate-shaped member 21A may be formed of two plate-shaped individual members 21aA and 21bA butted together in the thickness direction Y of the web 11A, and the plate-shaped individual members 21aA and 21bA may be joined to the first flange 12A. In this case, of the two plate-shaped individual members 21aA and 21bA, the end on the second side Y2 of the plate-shaped individual member 21aA arranged on the first side Y1 may be joined to the first flange 12A by the joining member 25, and the end on the first side Y1 of the plate-shaped individual member 21aA arranged on the second side Y2 may be joined to the first flange 12A by the joining member 25, thereby forming the plate-shaped member 21A.

[0042] 1, the plate-shaped member 20B is disposed outside the first lip channel steels 10A and 10B and is fixed to the first lip channel steel 10B. The plate-shaped member 20B is joined to the first flange 12B of the first lip channel steel 10B by a plurality of joining members 25 (not shown).

[0043] The floor 30 is fixed to the vertically middle portions of the pillars and extends along a horizontal plane. For example, the plate-like members 35A and 35B are sheathing boards. The plate-like members 35A and 35B are joined to the first flanges 12C and 12D of the second lip channel steels 10C and 10D by a plurality of joining members 25 (not shown), respectively. Roofing materials such as roof tiles (not shown) are fixed onto the plate-like members 35A and 35B. The eaves beams, rafters, second lip channel steels 10C and 10D, plate-like members 35A and 35B, and roofing material constitute a roof 43. In this example, the roof 43 is a gable roof. The floor 30 divides the interior of the building 1 into a lower first floor 1a and a second floor 1b above the first floor 1a. In other words, the building 1 is a two-story multi-story structure.

[0044] The building 1 may be a multi-story structure having three or more floors. For example, at least one of widths h, b, c and thickness t (described later) of lip channel steels 10A, 10B, 10C, 10D may be different from each other. Z-shaped steel, CT-shaped steel, etc. may be used instead of first lip channel steels 10A, 10B, and Z-shaped steel, CT-shaped steel, etc. may be used instead of second lip channel steels 10C, 10D.

[0045] [2. State of lip channel steel when negative bending acts on the support structure] Assume that a bending moment that results in negative bending acts on the support structure 40A configured as described above. Note that negative bending refers to a load state in which the flange on the tension side is constrained by a plate-like member when a bending moment acts, and corresponds to, for example, a roof or exterior wall that is subjected to negative pressure due to wind load. As an example, Fig. 5 shows a schematic diagram of a plate-shaped member 20A to which negative pressure F6 is applied. As shown in Fig. 5, a bending moment M1 acts on the first lip channel steel 10A due to negative pressure F6. The bending moment M1 is a bending moment around the strong axis O3 of the first lip channel steel 10A. This bending moment M1 pulls the first flange 12A in the axial direction Z, and compresses the second flange 13A in the axial direction Z. The first flange 12A (tension side edge) that is being pulled is restrained by the plate-like member 20A as described above. The second flange 13A (compression side edge) that is being compressed is not restrained and can move freely.

[0046] As shown in FIG. 1, a positive pressure F7 acts on the plate-shaped member 20B and the plate-shaped member 35B. The following describes a method for evaluating the elastic buckling stress of the first lip channel steel 10A in which the first flange 12A is constrained by the plate-like member 20A (hereinafter simply referred to as the evaluation method).

[0047] [3. Analysis conditions for lip channel steel] When performing the analysis, the dimensions and the like of the first lip channel steel 10A (hereinafter also abbreviated as lip channel steel 10A) are defined as shown in FIG. The width of the web 11A is defined as h (mm). The width of each of the flanges 12A and 13A is defined as b (mm). The width of each of the lips 14A and 15A is defined as c (mm). The thickness of each of the web 11A, flanges 12A and 13A, and lips 14A and 15A is defined as t (mm). As described above, the cross-sectional shape of the lip channel steel 10A is determined by four dimensions: the width h of the web 11A, the width b of the flanges 12A and 13A, the width c of the lips 14A and 15A, and the thickness t. The Young's modulus of lip channel steel 10A is E (N / mm 2 ) is stipulated.

[0048] An analytical model of the lip channel steel 10A is shown in Figure 6. As shown in Figure 6, the x-axis, y-axis, and z-axis of a right-handed Cartesian coordinate system are defined. The displacement and rotation of the portion of the first flange 12A on the line L7 are assumed to be as follows: Displacement: Fixed in the x-axis direction, free in the y-axis and z-axis directions. Rotation: Free around the x-axis and z-axis, fixed around the y-axis. Table 1 shows a list of parameters for the analysis model.

[0049] [Table 1]

[0050] The width h of the web 11A was set to three values: 50, 100, and 300 mm. For example, the value of (t / h) was set to 0.0033 or more and 0.06 or less. The values ​​of (b / h) and (c / h) were also varied, and a total of 1,425 cases were analyzed.

[0051] [4. Determining the type of evaluation quantity for elastic buckling stress based on the analysis results] Elastic buckling stress (N / mm 2 ) is the value found as the eigenvalue of the buckling of a member. It is known that the elastic buckling stress is proportional to the elastic modulus of the material (so-called Young's modulus). Therefore, Young's modulus and the elastic buckling stress are always in a linear proportional relationship, and the ratio is a dimensionless quantity. In addition, this elastic buckling stress is a buckling eigenvalue at a specific buckling half wavelength, and its value does not change depending on the length of the lip channel steel 10A. In other words, the elastic buckling stress is uniquely determined by the cross-sectional shape of the lip channel steel 10A perpendicular to the axial direction Z, regardless of the length of the lip channel steel 10A.

[0052] In FIG. 3, the elastically buckled lip channel steel 10A is indicated by a two-dot chain line L5. Focusing on the buckling mode of the elastically buckled lip channel steel 10A, it can be seen that the deformed shape of the lip channel steel 10A is a combination of a deformation in which the plate elements of the web 11A are warped and bent overall, and a buckling mode in which the first lip 14A on one side and the first flange 12A on one side of the lip channel steel 10A are twisted. In general, the buckling strength in a buckling mode in which the plate elements constituting the cross section of a member deform unevenly is greatly affected by the width-thickness ratio of the plate element (ie, web 11A) that causes the local deformation. Furthermore, considering that the elastic buckling stress intensity targeted by this embodiment is an extreme value having a specific buckling wavelength, it is considered that the influence of warpage torsion, the degree of which varies depending on the length of the lip channel steel 10A, is small; in other words, it is understood that the influence of cross-sectional torsion is greatly influenced by the so-called Saint-Venant torsion.

[0053] Therefore, based on previous knowledge, when quantitatively evaluating this elastic buckling stress, the evaluation formula can be expressed as equation (20) as a function with variables being the dimensionless quantity (t / h) used to quantitatively evaluate the local buckling strength of the web 11A and the dimensionless quantity (J / I0) used to quantitatively evaluate the torsional buckling strength of the member.

[0054]

number

[0055] where J is the Saint-Venant torsional constant (mm 4 ) and I0 is expressed by equation (21). I0=I x +I y +x c 2 A (21) where I x ,I y are the second moments of area around the x-axis and y-axis (mm 4 ), x c is the distance between the shear center and the centroid (mm), A is the cross-sectional area of ​​the lip channel steel 10A taken along a plane perpendicular to the y-axis (mm 2 )

[0056] In the following, to avoid confusion between the calculated value by the evaluation method of this embodiment and the result by eigenvalue analysis, the elastic buckling stress evaluated by the evaluation method of this embodiment will be referred to as the calculated elastic buckling stress σ crcal The elastic buckling stress obtained by eigenvalue analysis using the finite strip method (the elastic buckling stress considered to be the true value) is called the elastic buckling stress σ cr He says.

[0057] Furthermore, according to Non-Patent Document 1, it has been revealed that the local buckling strength of a plate is proportional to the square of (t / h). It is known that the torsional buckling strength of a plate is proportional to the first power of (J / I0). Therefore, based on the above background information, (σ cr When quantitatively evaluating the elastic buckling stress σ cr It is also natural to think that is proportional to a function of the square of (t / h) and the first power of (J / I0). Therefore, the evaluation formula for the elastic buckling stress is considered to be expressed by equation (24): Note that γ1 to γ3 in equation (24) are dimensionless constant coefficients.

[0058]

number

[0059] Figure 7 shows the calculated elastic buckling stress σ crcal and elastic buckling stress σ cr The values ​​of the constant coefficients γ1 to γ3 are calculated by the differential evolution method so as to minimize the deviation from the crcal / E), and the vertical axis represents (σ cr / E). Line L10 in FIG. crcal / E) and (σ cr / E) are equal to each other. The error △ is evaluated using the average value Ave of the evaluation results, the correlation coefficient R, and the coefficient of variation CV, as shown in equation (25).

[0060]

number

[0061] From Figure 7, as a function of (t / h) and (J / I0), (σ cr In the results shown in Figure 7, although the average value and correlation coefficient values ​​approach 1.0, the coefficient of variation is a large value of 0.268, and the calculated elastic buckling stress σ crcal and elastic buckling stress σ cr The gap between them becomes larger.

[0062] Based on the above-mentioned results of the study, in this embodiment, the elastic buckling stress σ cr We came up with the idea of ​​quantitatively evaluating this using equation (26), which uses four dimensionless quantities: the width-thickness ratio (t / h) of web 11A, which is a dimensionless quantity for taking into account the influence of local deformation of web 11A; (b / h) (the degree of constraint from flanges 12A, 13A to web 11A), which are parameters for evaluating the mutual effect between adjacent plate elements; (c / b) (the degree of constraint from lips 14A, 15A to flanges 12A, 13A); and (t / (h+2b+2c)), which is a parameter for taking into account the influence of the torsional rigidity of the plate.

[0063]

number

[0064] where f() is a function of the variables in ().

[0065] [5. Specific determination of each evaluation quantity] [5.1. (t / h) and (σ cr / E) First, (t / h) and (σ cr / E). Figure 8 shows the elastic buckling stress σ obtained from the buckling eigenvalue analysis. cr The analysis results are shown below for the case where the width b of the flanges 12A and 13A and the width c of the lips 14A and 15A are constant and the thickness t is changed. In FIG. 8, the horizontal axis represents (t / h) and the vertical axis represents (σ cr / E). Line L11 in FIG. 8 represents the relationship of equation (29).

[0066]

number

[0067] From Figure 8, (t / h) and (σ cr / E) is linearly proportional to the square of (t / h). cr / E) is linearly proportional to the first power of (t / h), and equation (30) is developed.

[0068]

number

[0069] Here, α1 and α2 to α4, which will be described later, are each dimensionless constants. It was confirmed that this tendency was observed in the same manner in all ranges analyzed this time.

[0070] [5.2.(b / h) and (σ cr / E) Next, (b / h) and (σ cr / E). 9 shows the analysis results when (b / h) is changed under the condition that the width c and thickness t of the lips 14A and 15A are constant. In FIG. 9, the horizontal axis represents (b / h) and the vertical axis represents (σ cr / E). Line L12 in FIG. 9 represents the relationship of equation (31).

[0071]

number

[0072] From Figure 9, based on the change in (b / h), (σ cr / E) changes nonlinearly. In other words, in the region where (b / h) is small, (σ cr / E) increases with increasing (b / h), but beyond a certain range, (σ cr We found that the value of / E) began to decrease. By finding this characteristic, in this embodiment, a new analytical method has been developed that can quantitatively evaluate the influence of changes in (b / h), as shown in equation (32).

[0073]

number

[0074] It was confirmed that this tendency was observed in the same way in all ranges analyzed this time. In addition, when (b / h) was about 0.4, (σ cr / E) is the maximum value.

[0075] [5.3.(c / b) and (σ cr / E) Next, (c / b) and (σ cr / E). FIG. 10 shows the analysis results when (c / b) is changed under the condition that the thickness t and the width b of the flanges 12A and 13A are constant. In FIG. 10, the horizontal axis represents (c / b) and the vertical axis represents (σ cr / E). Line L13 in FIG. 10 represents the relationship of equation (33).

[0076]

number

[0077] From Figure 10, based on the change in (c / b), (σ cr / E) increases linearly, and (c / b) and (σ cr / E) is approximated by a linear function, when (c / b) is zero, (σ crIt has been newly discovered that the value of (c / b) is not zero. When (c / b) is zero, it means that the length of the lips 14A and 15A is zero. Even if the lip channel steel 10A is changed to a channel steel without lips 14A, 15A, its overall buckling strength simply converges to the elastic buckling stress of a channel steel without lips, and does not become zero. Taking note of this characteristic, in this embodiment, a method for quantitative evaluation using equation (34) has been developed so that (c / b) increases as the length of the lips 14A, 15A gradually increases.

[0078]

number

[0079] [5.4.(t / (h+2b+2c)) and (σ cr / E) Next, (t / (h+2b+2c)) and (σ cr / E). In the buckling mode of this analysis, the second flange 13A (compression side edge) of the lip channel steel 10A undergoes a buckling deformation that causes it to twist significantly. In other words, the resistance of the member to torsion is also thought to affect the elastic buckling stress. First, let us consider that there is no influence of (t / (h+2b+2c)), and then consider (σ cr / E) was evaluated using equation (37) with the value of f(t / h, b / h, c / b).

[0080]

number

[0081] Then, we attempt to quantitatively evaluate the influence by analyzing the relationship between the correlation coefficient R and (t / (h+2b+2c)). The constants α1 to α3 are calculated from equation (37) (σ crcal / E), which can be calculated from eigenvalue analysis (σ cr / E) is determined so that the error Δ is minimized.

[0082] 11 shows the change in correlation coefficient R with respect to (t / (h+2b+2c)). In FIG. 11, the horizontal axis represents (t / (h+2b+2c)), and the vertical axis represents correlation coefficient R. From Figure 11, a new tendency was found in which the value of the correlation coefficient R gradually increases as (t / (h+2b+2c)) increases. An increase in (t / (h+2b+2c)) means that the contribution of the plate thickness to the developed length of the lip channel steel 10A increases. As a result, the resistance to torsion increases relatively, and the elastic buckling stress σ cr is thought to be on the rise. Therefore, in this embodiment, the idea is to evaluate this influence using equation (38). Note that the constants α1, α2, α3, and α4 are determined so as to minimize the evaluation error by equation (38). That is, the function f() is calculated by the formula (39). It is expressed as the formula:

[0083]

number

[0084] [6. Results of performance evaluation using this evaluation method] Figure 12 shows the results of performance evaluation using this evaluation method. In Figure 12, the horizontal axis represents (σ crcal / E), and the vertical axis represents (σ cr / E). By using this evaluation method, the correlation coefficient was 0.999 and the coefficient of variation was 0.025. Compared to the evaluation method obtained using the general method shown in Figure 7, the coefficient of variation was significantly reduced (from 0.268 to 0.025), and the evaluation accuracy was improved by more than 10 times.

[0085] [7. Desirable range of constants α1 to α4] Next, the desirable range of the constants α1 to α4 will be considered. When considering structural design, the accuracy required for the evaluation method may require a degree of precision that ensures a safe evaluation of performance. Here, α1 is a coefficient (constant) applied to the entire formula in equation (38), and the change in its value is proportional to (σ cr Therefore, in this embodiment, in the above-mentioned design formula, the value of (σ cr / σ crcal The error △ of the analytical method was evaluated using equation (41) so that the value obtained by subtracting three times the standard deviation σ from the average value of (σ) becomes 1.0, and we considered the desirable range of the constant α1 so that this evaluation method can reliably evaluate performance on the safe side.

[0086]

number

[0087] Table 2 shows the differences in the evaluation results for the constants α1 to α4.

[0088] [Table 2]

[0089] The values ​​of constants α2 to α4 were not changed, and only the value of constant α1 was changed. Note that it is constants α2 to α4 that affect the coefficient of variation CV, but constant α1 does not affect the coefficient of variation CV. For example, let us consider the case where the error △ is evaluated using equation (25), as in the first row from the top of Table 2. In this case, the constant α1 is 0.117, the constant α2 is 0.160, the constant α3 is 0.347, the average value Ave is 1.004, the correlation coefficient R is 0.999, and the coefficient of variation CV is 0.0253. Calculated elastic buckling stress σ crcal The elastic buckling stress σ cr The rate of evaluation on the safe side (σ crcal ≦σ cr The percentage of people who evaluated it as such was 67%. On the other hand, when the error △ is evaluated using Eq. (41), as in the second row from the top of Table 2, the calculated elastic buckling stress σ crcal The elastic buckling stress σ crThe percentage of people who chose to be on the safe side was 100%.

[0090] In addition, by evaluating the error △ using equation (41), the elastic buckling stress of the members could be evaluated on the safe side in all cases. From this, in this embodiment, when the constant α1 satisfies (42), quantitative evaluation of the elastic buckling stress can be performed with high accuracy, with R being 0.999 and CV being 0.0253. 0.108≦α1≦0.117 (42) Furthermore, if the constant α1 satisfies (42), the calculated elastic buckling stress σ crcal It is possible to evaluate it on the safe side.

[0091] 8. Consideration of coefficient of variation Next, we will discuss the coefficient of variation CV. In the evaluation method of this embodiment, when the design was made to minimize the error △, the coefficient of variation was 0.0253. In contrast, the coefficient of variation in the current method (when the error △ was evaluated using equation (25)) was 0.268, which is approximately 10 times the value. Therefore, in this embodiment, a range was searched for that would always result in a coefficient of variation smaller than that of the current evaluation method. Here, optimization calculations were performed assuming that the constants α2 to α4 are greater than the optimal value and that the constants α2 to α4 are smaller than the optimal value when the value of the coefficient of variation is 0.05 or less. Then, the upper and lower limits of the constants α2 to α4 are determined, and as shown in Table 3, the values ​​within the range are calculated. 3 Eight different combinations were tested.

[0092] [Table 3]

[0093] For example, if the constants α2 to α4 in the first row from the top of Table 2 are smaller than the optimal values, and if constant α2 is 0.129, constant α3 is 0.0624, and constant α4 is 8.14, the coefficient of variation will be 0.050. It was found that the coefficient of variation was smaller in all eight combinations than in the method based on the current method. As a result, the intended effect of this embodiment is to suppress the variation from the true value of the elastic buckling stress and to obtain the calculated elastic buckling stress σ crcal The specific range of values ​​in which the above equations can be obtained has been clarified as follows: That is, the range in which the constants α2, α3, and α4 satisfy the equations (43), (44), and (45), respectively. 0.129≦α2≦0.211 (43) 0.0624≦α3≦0.729 (44) 8.14≦α4≦8.32 (45)

[0094] In addition, in the support structure 40A, the displacement in the thickness direction Y (direction of the weak axis O4) of the first flange 12A pulled by the bending moment M1 and the rotation around the material axis O1 may be discretely joined in the axial direction Z. At this time, it is desirable to arrange the spacing in the axial direction Z of the joints made by the multiple joining members 25 so that the slenderness ratio of the lip channel steel 10A is 20 or less when the thread pitch is considered to be half the buckling wavelength, for example, with reference to Non-Patent Document 1.

[0095] [9. Desirable shape of support structure] Conventionally, steel materials with a yield strength of 280 MPa have been widely used for thin-plate building materials. 2 There is a description of the use of steel materials, and the material strength of the thin lightweight steel currently in practical use is 345N / mm 2 is found to be the highest intensity. In recent years, as the scale of architectural structures using lightweight steel plates has increased, increasing the strength of components has become a major issue.

[0096] Therefore, in this embodiment, the strength of the lip channel steel 10A is increased by using a steel material having a yield strength of 500 MPa or more, which is stronger than conventional steel materials. In actual structures, there are two cases where the maximum strength of a member is determined by elastic buckling, and where the member reaches its maximum strength by plasticizing the material before elastic buckling. Of these, the only case where a member can be expected to have higher strength by increasing the strength of the material is when the member reaches its maximum strength by plasticizing the material. When a bending moment acts on the lip channel steel 10A, which is not restrained by surrounding members, the lateral buckling strength of the structural steel falls far short of the material strength depending on the length of the lip channel steel 10A, even if high-strength steel is used. In this case, the member elastically buckles before reaching material yield, and the change in material strength does not affect the member strength.

[0097] Therefore, in this embodiment, by attaching a plate-shaped member 20A to the first flange 12A of the lip channel steel 10A on which the bending moment M1 acts, the deformation of the first flange 12A in the thickness direction Y and the rotation about the material axis O1 are restrained. This provides a support structure 40A that significantly increases the elastic buckling stress of the lip channel steel 10A beyond the lateral buckling strength, thereby improving the member's strength through higher strength. As described in Non-Patent Document 1, the design standard strength of currently widely used thin-plate lightweight steel (yield strength of lip channel steel 10A) is a maximum of F=345N / mm 2 The proportional limit of steel as a material is generally known to be 0.6 times the yield strength. In other words, in the support structure 40A where the constraint by the plate-like member 20A acts, the elastic buckling stress is 345 N / mm 2 A value of 0.6 times or more is a preferable range in which the effect of increasing the strength of the support structure 40A due to the increased strength can be expected.

[0098] Therefore, the elastic buckling stress σ obtained from eigenvalue analysis cr Based on this, the allowable stress f b was calculated according to equations (48) to (50) described in Non-Patent Document 1.

[0099]

number

[0100] In addition, the allowable stress f b is the maximum allowable stress acting on the member cross section. When the stress acting on the member cross section is the allowable stress f b When the load exceeds this limit, the member collapses. F is the yield strength of lip channel steel 10A (N / mm 2 ) For the support structure 40A in which the first flange 12A to be tensioned is restrained by the plate-like member 20A, the yield strength F of the lip channel steel 10A is set to 345 N / mm 2 to 500N / mm 2 The rate of increase in strength was investigated when the load was increased to .

[0101] where f b_345 The yield strength F is 345N / mm 2 f is the allowable stress obtained from the results of eigenvalue analysis under the condition b_500 The yield strength F is 500N / mm 2 The allowable stress is defined as the stress obtained from the results of eigenvalue analysis under the condition of (f b_500 / f b_345 ) is greater than 1.0, it is possible to find the cross-sectional specifications of components that can be expected to have a high strength effect. On the other hand, in a structure in which one side of the lip channel steel 10A is restrained by a plate-shaped member 20A, although the elastic buckling stress is increased above the lateral buckling strength, there has been no method to unambiguously evaluate this elastic buckling stress, and therefore it has not been possible to find specific member specifications that would be effective. Therefore, in this invention, a new dimensionless quantity K was discovered based on the analytical method for elastic buckling stress invented based on the above analytical study. b_500 / f b_345 ) and the dimensionless quantity K obtained by equation (53) for quantitatively evaluating the elastic buckling stress obtained through the study of this embodiment.

[0102]

number

[0103] In FIG. 13, the horizontal axis represents the dimensionless quantity K, and the vertical axis represents (f b_500 / f b_345 ) From Figure 13, when the dimensionless quantity K exceeds 0.000996, (f b_500 / f b_345 ) becomes larger than 1.0. Therefore, it has been newly discovered that a support structure 40A including lip channel steel 10A in which the dimensionless quantity K satisfies equation (54) can be expected to have an increased strength due to increased strength. Note that the upper limit value of this threshold (0.0130) is the maximum value of the dimensionless quantity K within the range analyzed in this embodiment.

[0104]

number

[0105] Also, from Figure 13, when the dimensionless quantity K exceeds 0.0015, (f b_500 / f b_345 ) is 1.2 or more. Therefore, it has been found that in the support structure 40A equipped with the lip channel steel 10A in which the dimensionless quantity K satisfies equation (55), it is possible to reliably increase the strength of the members by 20% or more.

[0106]

number

[0107] While increasing the strength of materials contributes to increasing the strength of components, there is a problem in that it reduces on-site workability, especially when driving drill screws without drilling a pilot hole. Therefore, in this embodiment, the yield strength F is 780 N / mm 2 The upper limit of the yield strength of the material is set as That is, (b / h), (t / h), (c / h), the width h of the web 11A, and the design reference strength F satisfy the formulas (58) to (62), respectively.

[0108]

number

[0109] Equations (58) to (61) are derived from the numerical range of the specific cross-sectional specifications of the lip channel steel 10A for which the buckling eigenvalue analysis was performed.

[0110] [10. Elastic buckling stress evaluation device] FIG. 14 shows an elastic buckling stress evaluation device (hereinafter simply referred to as evaluation device) 50 that can preferably carry out the above evaluation method. The evaluation device 50 evaluates the elastic buckling stress of a lip groove cross-section member 10A when a bending moment M1 acts on it. The evaluation device 50 is a computer and includes a CPU (Central Processing Unit) 51, a main memory device 55, an auxiliary memory device 60, an input / output interface (IO-I / F) 65, and a recording / reproducing device 70. The CPU 51, the main memory device 55, the auxiliary memory device 60, the input / output interface 65, and the recording / reproducing device 70 are connected to one another by a bus 75. The main storage device 55 is a RAM (Random Access Memory) or the like that serves as a work area for the CPU 51 or the like. The input / output interface 65 is connected to an input device 66 such as a keyboard and a mouse, and a display device 67 . A recording / playback device 70 records and plays back data on a recording medium 71 such as a USB (Universal Serial Bus) memory.

[0111] The auxiliary storage device 60 is a hard disk drive device or the like that stores various data, programs, etc. The auxiliary storage device 60 stores an elastic buckling stress evaluation program (hereinafter simply referred to as an evaluation program) 61 for causing the computer to function as the evaluation device 50, various programs such as an OS program, etc. The various programs including the evaluation program 61 are loaded into the auxiliary storage device 60 from a recording medium 71 via a recording / playback device 70. The evaluation program 61, etc. are stored in the recording medium 71. These programs may be loaded into the auxiliary storage device 60 from a disk-type recording medium such as a CD or DVD, or from an external device via a communication device (not shown).

[0112] The CPU 51 executes various arithmetic processes. The CPU 51 functionally includes an evaluation unit 52. The evaluation unit 52 calculates the elastic buckling stress σ calculated by the equation (26). crcal The elastic buckling stress is evaluated using The evaluation unit 52 is a functional component of the CPU 51. The evaluation unit 52 functions when the CPU 51 executes an evaluation program 61 stored in the auxiliary storage device 60. The evaluation program 61 is a program for the evaluation device 50. The evaluation program 61 causes the evaluation device 50 to function as the evaluation unit 52.

[0113] [11. Evaluation method for elastic buckling stress] FIG. 15 shows a flowchart of the evaluation method S1 of this embodiment. In evaluation method S1, the calculated elastic buckling stress σ obtained by equation (26) crcal The evaluation step S5 is carried out to evaluate the elastic buckling stress using the above formula. Also, a lip channel steel 10A is manufactured, the elastic buckling stress of which is evaluated by the lip channel steel manufacturing method (hereinafter simply referred to as manufacturing method) and evaluation method S1 of this embodiment.

[0114] 12. Effects of this embodiment As described above, in the evaluation method S1 and the evaluation program 61 of this embodiment, the inventors have conducted extensive research and found that the elastic buckling stress of the first lip channel steel 10A when the bending moment M1 acts and the first flange 12A is pulled is (σ crcalIt was found that (t / h), (b / h), (c / b), and (t / (h+2b+2c)) are functions of (t / h), (b / h), (c / b), and (t / (h+2b+2c)) according to equation (26). Therefore, equation (26) can be used to evaluate the elastic buckling stress of the first lip channel steel 10A when a bending moment acts on the first lip channel steel 10A with only the first flange 12A, which receives a tensile force, restrained.

[0115] The function f() is calculated by equation (39). Therefore, the calculated elastic buckling stress σ can be calculated by using equation (39) in which the function f() is specifically defined using constants α1 to α4 in equation (26). crcal can be calculated more precisely. The constant α1 satisfies equation (42). Therefore, the calculated elastic buckling stress σ evaluated by evaluation method S1 is crcal can be evaluated on the safe side to a certain extent.

[0116] The constant α2 satisfies equation (43). Therefore, the calculated elastic buckling stress σ2 can be calculated by suppressing the deviation from the true value of the elastic buckling stress. crcal can be obtained. The constant α3 satisfies equation (44). As a result, the deviation from the true value of the elastic buckling stress is suppressed with respect to the constant α3, and the calculated elastic buckling stress σ crcal can be obtained. The constant α4 satisfies equation (45). Therefore, for the constant α4, the deviation from the true value of the elastic buckling stress is suppressed, and the calculated elastic buckling stress σ crcal can be obtained.

[0117] Furthermore, the manufacturing method of this embodiment makes it possible to manufacture a first lip channel steel 10A in which a bending moment M1 acts when the first flange 12A is subjected to a tensile force, and in which the elastic buckling stress has been evaluated. Furthermore, in the support structure 40A of this embodiment, when a bending moment acts on the first lip channel steel 10A with only the first flange 12A, which is subjected to tensile force, restrained, the allowable stress of the first lip channel steel 10A can be effectively increased by increasing the yield strength of the first lip channel steel 10A.

[0118] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and modifications, combinations, deletions, etc. of the configuration may also be made within the scope that does not deviate from the gist of the present invention. For example, in the above embodiment, it is not necessary to satisfy at least one of the equations (42) to (45) for the constants α1 to α4.

[0119] As shown in Fig. 16, the building 2 may be composed of only the first story 2a. In this example, the first lip channel steels 10A, 10B extend along a horizontal plane. In this manner, the orientation of the first lip channel steels 10A, 10B relative to the plate-like members 20A, 20B is not limited. The lip channel section member is the first lip channel steel 10A. However, the lip channel section member is not limited to this as long as it is a member having a web, a pair of flanges, and a pair of lips. The lip groove section is constructed from a continuous plate element, but may also have holes drilled into it to allow for the passage of electrical wiring, piping, etc. [Explanation of symbols]

[0120] 10A No. 1 lip channel steel (lip channel cross section member) 11A Web 12A First flange (flange) 13A Second flange (flange) 14A First Lip (Lip) 15A Second Lip (Lip) 20A, 20B, 21A, 35A, 35B Plate-shaped members 40A,41A support structure 50 Evaluation device (elastic buckling stress evaluation device) 52 Evaluation Department 61 Evaluation program (elastic buckling stress evaluation program) O1 Material axis S1 Evaluation method (evaluation method for elastic buckling stress) S5 Evaluation process X Width direction Y thickness direction

Claims

1. A lip groove cross-section member having a web, a pair of flanges provided at both ends in the width direction of the web so as to extend in the thickness direction of the web, and a pair of lips extending toward each other from the tip ends of the pair of flanges, The first flange, which is one of the pair of flanges, is restrained from deformation in the thickness direction of the web and from rotation about the material axis of the lip groove cross-section member, A method for evaluating an elastic buckling stress of a lip groove section member, in which a bending moment about a strong axis of the lip groove section member acts on the lip groove section member, causing the first flange to be pulled, comprising: Calculated elastic buckling stress σ calculated by equation (1) ｃｒｃａｌ An evaluation method for elastic buckling stress, comprising: performing an evaluation step of evaluating the elastic buckling stress using the above-mentioned method. where E is the Young's modulus of the lip groove cross section member (N / mm ２ ), h is the width of the web (mm), b is the width of each of the pair of flanges (mm), c is the width of each of the pair of lips (mm), t is the thickness of each of the web, the pair of flanges, and the pair of lips (mm), and f() is a function of the variables in (). [Equation 1]

2. The method for evaluating elastic buckling stress according to claim 1 , wherein the function f() is determined by the following equation (2): However, α １ , α ２ , α ３ , α ４ are dimensionless constants. [Equation 2]

3. The constant α １ The method for evaluating elastic buckling stress according to claim 2, wherein the formula (3) is satisfied. ０．１０８≦α １ ≦０．１１７ ・・（３）

4. The constant α ２ The method for evaluating elastic buckling stress according to claim 2, wherein the formula (4) is satisfied. ０．１２９≦α ２ ≦０．２１１ ・・（４）

5. The constant α ３ The method for evaluating elastic buckling stress according to claim 2, wherein the formula (5) is satisfied. ０．０６２４≦α ３ ≦０．７２９ ・・（５）

6. The constant α ４ The method for evaluating elastic buckling stress according to claim 2, wherein the formula (6) is satisfied. ８．１４≦α ４ ≦８．３２ ・・（６）

7. A method for manufacturing a lip groove section member, the method comprising: manufacturing the lip groove section member whose elastic buckling stress has been evaluated by the method for evaluating elastic buckling stress of claim 1.

8. A lip groove cross-section member having a web, a pair of flanges provided at both ends in the width direction of the web so as to extend in the thickness direction of the web, and a pair of lips extending toward each other from the tip ends of the pair of flanges, The first flange, which is one of the pair of flanges, is restrained from deformation in the thickness direction of the web and from rotation about the material axis of the lip groove cross-section member, a program for evaluating an elastic buckling stress of an evaluation device for evaluating an elastic buckling stress of the lip groove section member when a bending moment about a strong axis of the lip groove section member acts on the lip groove section member and the first flange is pulled, The evaluation device Calculated elastic buckling stress σ calculated by equation (7) ｃｒｃａｌ and a program for evaluating elastic buckling stress, which functions as an evaluation unit that evaluates the elastic buckling stress using the above program. where E is the Young's modulus of the lip groove cross section member (N / mm ２ ), h is the width of the web (mm), b is the width of each of the pair of flanges (mm), c is the width of each of the pair of lips (mm), t is the thickness of each of the web, the pair of flanges, and the pair of lips (mm), and f() is a function of the variables in (). [Equation 3]

9. a lip groove section member; a plate-shaped member joined to the lip groove cross-section member; A support structure comprising: The lip groove cross-section member has a web, a pair of flanges provided at both ends in the width direction of the web so as to extend in the thickness direction of the web, and a pair of lips extending toward each other from the tip ends of the pair of flanges, The plate-like member is joined to a first flange, which is one of the pair of flanges, and restricts deformation of the first flange in the thickness direction of the web and restricts rotation of the lip groove cross-section member about a material axis line, A bending moment acts on the lip groove section member about a strong axis of the lip groove section member, causing the first flange to be pulled, A support structure that satisfies equations (8) to (13). where h is the width of the web (mm), b is the width of each of the pair of flanges (mm), c is the width of each of the pair of lips (mm), t is the thickness of each of the web, the pair of flanges, and the pair of lips (mm), and F is the yield strength of the lip groove cross-section member (N / mm ２ ) [Equation 4]

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