Structural steel sections and truss structures using them

Abstract

To provide a shaped steel for structure used for civil engineering / a building structure having not only basic structural performance as a structural member but transportability and maintainability, and a truss structure using the same.SOLUTION: A shaped steel for structure, having a sectional shape of an equal angle shape, an edge angle θ1 from 60° or greater to 120° or smaller, comprises: width C shorter than width B of a side edge at a tip of the side edge; and an oblique lip with a lip angle θ2 over 0° to θ1 or less at the sides approaching to each other from an extended line of the side edge as placing the edge angle therebetween. The present invention provides the shaped steel for structure having not only basic structural performance such as buckling resistance and bending strength as a structural member but transportability (including stackability upon storing and transporting) and maintainability while having open cross section structure of relatively thin board thickness, and a truss structure using the same.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to structural steel shapes and a truss structure using the same, and more particularly to structural steel shapes used in civil engineering and building structures including truss structures such as iron towers, bridges, and cranes, and a truss structure using the same.

Background Art

[0002] In the field of civil engineering and construction, as structural members for constructing steel frame structures such as truss structures, steel materials having various materials (strength, ductility, toughness, etc.) and cross-sectional shapes including thickness (steel pipes, H-shaped steel, angle steel, etc.) are used according to the scale and application of the equipment.

[0003] For example, in the case of a transmission iron tower, the structural form varies depending on the transmission scale. In the case of general small and medium scales, angle steel iron towers (see Patent Document 1) account for the majority, and in the case of large-scale power transmission, steel pipe iron towers (see Patent Document 2) are adopted. Angle steel is used in general small and medium-scale iron towers because, in addition to the strength required for the constituent members and the structure being small enough not to be a problem even with angle steel, the cross-sectional shape is a simple angle (L-shaped), so it has excellent transportability as a member (including stackability during storage and transportation) and assemblability. Also, since it has an open cross-section, it has characteristics in terms of cost from manufacturing to maintenance management, such as being easy to ensure maintainability.

[0004] On the other hand, steel pipes are used for large-scale power transmission iron towers because they have a closed cross-section structure and extremely high structural performance compared to angle steel in terms of basic structural performance required for structural members such as buckling resistance and bending strength. However, in the case of steel pipe iron towers, as disclosed in, for example, Patent Document 2, in addition to the maintenance problem that it is not easy to inspect or repair the inside of the closed cross-section steel pipe, the details such as joints become complicated, so there is a problem that a significant increase in manufacturing cost cannot be avoided compared to the case of using angle steel.

[0005] In response to the problem of closed-section structures of steel pipes as structural members, Patent Document 3 discloses a building column 50, as shown in Figure 8, in which one corner of a rectangular steel pipe cross section is cut out and the column is composed of four side wall plates 51 to 54. Furthermore, in such a building column 50, by forming the side wall plates 51 and 54 with openings 55 having an opening width W2 of 45% or more of the maximum width W1 of the side wall and no more than 10 times the thickness T1 of the side wall plate, it is possible to maintain the strength characteristics of the rectangular steel pipe while ensuring workability in the hollow section. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2000-184565 [Patent Document 2] Japanese Patent Publication No. 2004-286114 [Patent Document 3] Japanese Patent Publication No. 2020-165221 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, there has been a trend toward larger and longer-lasting power transmission towers, and even in the conventional angle steel towers that have been used for small to medium-sized structures, it has become necessary to adopt high-performance components. Furthermore, many power transmission towers built during the period of rapid economic growth are aging and need to be replaced. In addition to maintenance issues after construction, there is a need for technological development to improve productivity during replacement, including structural rationalization, construction efficiency, and weight reduction.

[0008] In contrast, there is a need for structural steel sections that improve characteristics affecting structural performance, such as buckling resistance and corrosion resistance, compared to angle steel sections that have been widely used in conventional steel towers. However, the member described in Patent Document 3, which has one corner of a square steel pipe cross section cut out, is primarily intended to improve the structural performance as an open-section structural steel section. As a result, the width of the side wall plate must be left large, meaning the opening width is small, and maintenance problems remain, such as difficulty in inserting inspection equipment or repair equipment depending on the placement of the member. Furthermore, it does not have the advantages of general angle steel sections in terms of transportability (including stackability during storage and transport).

[0009] This invention has been made in view of the above-mentioned problems, and aims to provide structural steel sections for use in civil engineering and building structures, which are open cross-section structures with relatively thin plate thicknesses, and which, in addition to basic structural performance such as buckling resistance and bending strength as structural members, also possess transportability (including stackability during storage and transport) and maintainability, as well as structural steel sections and truss structures using the same. [Means for solving the problem]

[0010] [1] A cross section perpendicular to the longitudinal direction, (a) It has a mountain shape, (b) The widths B of the sides on both sides are approximately equal, (c) The side angle θ1 formed by the two sides is 60° or more and 120° or less, (d) Lips symmetrical with respect to the strong axis of the mountain-shaped cross-section are added to the ends of each of the two sides, Structural steel sections, The lip has a width C shorter than the width B of the side edge, and is inclined from the extension line of the side edge toward the side edge angle, with a lip angle θ2 greater than 0° and less than or equal to the side angle θ1.

[0011] [2] The structural steel section according to [1], wherein the lip angle θ2 is smaller than the angle at which the lip is substantially perpendicular to the weak axis of the cross-section of the structural steel section.

[0012] [3] The structural steel section described in [1] or [2], wherein the width C of the lip is equal to or greater than the required lip width Cmin calculated by the following formula (1).

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[0013] [4] A structural steel section according to any one of [1] to [3], wherein the side of the structural steel section is divided into a first side on the side corner side and a second side on the side tip side by providing an in-side bend at a predetermined length from the tip of each of the two sides of the structural steel section, and the bending angle of the in-side bend is set to a bending angle where the extensions of the two second sides are substantially perpendicular to each other, while maintaining the side angle θ1 and the lip angle θ2, and the second side is a member connecting portion.

[0014] A truss structure whose constituent members are structural steel shapes as described in any of [5][1] to [4]. [Effects of the Invention]

[0015] According to the structural steel shape of the present invention and the truss structure using the same, the cross-sectional shape is an equilateral mountain shape, the side angle θ1 is 60° or more and 120° or less, and at the tip of the side, it has a width C shorter than the width B of the side, and on the side approaching each other across the side angle from the extension line of the side, a structural steel shape is adopted that has a lip inclined with a lip angle θ2 of more than 0° and less than or equal to the side angle θ1. By doing so, it is possible to provide a structural steel shape and a truss structure using the same that have both transportability (including stackability during storage and transportation) and maintainability in addition to basic structural performance such as buckling resistance as a structural member, while having an open cross-sectional structure with a relatively thin plate thickness.

Brief Description of Drawings

[0016] [Figure 1] It is a figure explaining the cross-sectional shape of the structural steel shape which concerns on Embodiment 1. [Figure 2] It is a figure explaining the structural steel shape which concerns on Embodiment 1 in a perspective view. [Figure 3] It is a figure explaining the relationship between the lip angle of the lip channel steel and the moment of inertia of the weak axis cross-section. [Figure 4] It is a figure explaining the relationship between the lip angle of the lip channel steel and the size of the gap between the lip channel steels when the lip channel steels are stacked. [Figure 5] It is a figure explaining the relationship between the lip angle of the lip channel steel and the local buckling strength. [Figure 6] It is a figure explaining the cross-sectional shape of the structural steel shape which concerns on Embodiment 2. [Figure 7] It is a figure explaining an example in which the structural steel shape according to Embodiments 1 and 2 is applied to a transmission tower which is a truss structure shown in (a), in horizontal cross-sectional views (b) to (d) in which the part of the structural steel shape is enlarged and schematically shown in the direction of the A-A cross-section arrow of (a). [Figure 8] It is a figure explaining a building column material similar to the lip channel steel according to the prior art in a perspective view.

Modes for Carrying Out the Invention

[0017] Embodiments of the present invention will be described in detail below with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and their descriptions will not be repeated. However, the present invention is not limited to the embodiments shown below.

[0018] (Embodiment 1) Figure 1 is a cross-sectional view showing the structural steel section 1 according to Embodiment 1, and Figure 2 is a perspective view showing the structural steel section 1 according to Embodiment 1. The structural steel section 1 according to Embodiment 1 will be described below with reference to Figures 1 and 2.

[0019] As shown in Figure 1, the structural steel section 1 according to Embodiment 1 has a cross section perpendicular to the longitudinal direction, (a) It has a mountain shape, (b) The widths B of the sides 5 on both sides are approximately equal to each other, (c) The angle θ1 formed by the two sides 5 is 60° or more and 120° or less, (d) A structural steel section 1 having lips 7 attached to the ends of each of the two side edges 5, which are symmetrical with respect to the strong axis of the mountain-shaped cross section, The lip 7 has a width C shorter than the width B of the side edge 5, and is inclined from the extension line of the side edge 5 toward the side that is closer to the side edge angle, with a lip angle θ2 that is greater than 0° and less than or equal to the side edge angle θ1.

[0020] Figure 1 is a cross-sectional view of a structural steel section 1 according to Embodiment 1, where the side angle θ1 is approximately 90° and the lip angle θ2 is approximately 45°. It also shows the xy rectangular coordinate system in which the outer surfaces of the two side edges 5 coincide with the coordinate axes, as well as the strong axis x' and weak axis y' of this structural steel section 1. Figure 2 is a perspective view of the structural steel section 1 according to Embodiment 1, having the cross-sectional shape shown in Figure 1, as seen from the side of the side corner 3.

[0021] As can be seen from Figures 1 and 2, the structural steel section 1 according to Embodiment 1 has a mountain-shaped cross-section and an open cross-section, which makes it highly transportable, including stackability during storage and transport. Furthermore, it offers excellent maintainability, as it eliminates the difficulties in inspecting and repairing the inner surface that are present in closed cross-section structures.

[0022] Furthermore, the structural steel section 1 according to Embodiment 1 has widths B of both sides 5 that are approximately equal, and can be said to have excellent structural symmetry as a structural member. The reason why the width C of the lip 7 is shorter than the width B of the side 5 is that if the width C of the lip 7 is larger than or equal to the width B of the side 5 which the lip 7 is stiffening target, the lip 7 itself would require the same stiffening measures as the side 5 which it is stiffening target, and therefore such wide lips are no longer included.

[0023] As described above, the structural steel section 1 according to Embodiment 1 is characterized in that, among equal-leg angle steel sections with a lip, the cross-sectional shape is particularly characterized in the following two points: (1) the side angle θ1 is 60° or more and 120° or less, and (2) the lip 7 is inclined on the side approaching each other across the side angle from the extension line of the side 5, with a lip angle θ2 that is greater than 0° and less than or equal to the side angle θ1.

[0024] The side angle θ1 is selected within the range of 60° to 120° depending on the application of the structural steel section 1. For example, the structural steel section 1 according to Embodiment 1, in which the side angle θ1 is approximately 90°, is suitable for columns and the like when the horizontal cross-sectional shape is quadrilateral, and the structural steel section 1 according to Embodiment 1, in which the side angle θ1 is 60° to 120°, is suitable for columns and the like when the horizontal cross-sectional shape is triangular to polygonal, or when a part of the horizontal cross-section includes the shape of a corner of a triangle to polygon.

[0025] Next, regarding the requirement that the lip 7 of the structural steel section 1 according to Embodiment 1 is inclined on the side approaching each other across the side angle from the extension line of the side edge 5, having a lip angle θ2 that is greater than 0° and less than or equal to the side angle θ1, first, the results of preliminary studies from the viewpoint of improving the weak-axis second moment of area will be explained using Figures 3 and 4, and then, the results of preliminary studies from the viewpoint of improving the local buckling strength will be explained using Figure 5.

[0026] Figure 3 shows the results of calculating the weak-axis second moment of area for a structural steel section 1 according to Embodiment 1, which satisfies the conditions for structural steel section 1 according to Embodiment 1 except for the lip angle θ2, with a side angle θ1 of 90°, a plate thickness of 6 mm, a side width B of 300 mm, and a lip width C of 60 mm, when the lip angle θ2 is changed from 0° to 180°. As shown in Figure 3, when the lip angle θ2 is in the range from the direction along the side 5 (θ2=0°) to the angle corresponding to the side angle θ1 (θ2=θ1=90°) (0°<θ2≦θ1=90°), the weak-axis second moment of area Iy' of the structural steel section 1 according to Embodiment 1 is improved compared to the angle steel section (θ2=0°), thus indicating that the overall buckling strength can be increased.

[0027] In the structural steel section 1 according to Embodiment 1, it is preferable that the lip angle θ2 is smaller than the angle at which the lip is approximately perpendicular to the weak axis of the cross-section of the structural steel section 1. As shown in Figure 3, when the lip angle θ2 is perpendicular to the weak axis of the cross-section of the member (for example, when θ1 = 90°, θ2 = θ1 / 2 = 45°), the weak axis second moment of area is maximized, making it possible to maximize the overall buckling strength, and this effect is maintained at a high level even in the range where the lip angle θ2 exceeds 0°. Also, as shown in Figure 4 (see also Figure 1), in this range, as the lip angle θ2 decreases, the tip of the lip 7 widens beyond the tip of the side edge 5 at the base of the lip 7, making the width of the opening 9 larger. As a result, the size of the gap between structural steel sections 1 that occurs when the structural steel sections 1 are stacked (see gap cross-sectional area A in Figure 4) decreases sharply, improving transportability.

[0028] Next, regarding the requirement that the lip 7 of the structural steel section 1 according to Embodiment 1 is inclined on the side approaching each other across the side angle from the extension line of the side edge 5, with a lip angle θ2 that is greater than 0° and less than or equal to the side angle θ1, the results of a preliminary study from the viewpoint of improving local buckling strength will be explained using Figure 5.

[0029] Figure 5 shows the results of calculating the local buckling strength for a structural steel section 1 according to Embodiment 1, where the conditions are the same as the structural steel section 1 according to Embodiment 1, except for the lip angle θ2, with a side angle θ1 of 90°, a plate thickness of 6 mm, a side width B of 300 mm, and a lip width C of 60 mm, when the lip angle θ2 is changed from 0° to 180°. As shown in Figure 5, it can be confirmed that by providing the lip 7 of the structural steel section 1 according to Embodiment 1, the local buckling strength of the side 5 can be increased with increasing lip angle θ2 in the range of angles where the lip angle θ2 is greater than 0° and less than or equal to the side angle θ1. Furthermore, in the range of θ2 = 30° to 150°, the local buckling strength hardly decreases, and it can be seen that the entire cross-section of the member is utilized efficiently and does not fall below the yield strength of commonly used SS400 or SM490 materials.

[0030] Local buckling strength decreases as the width-to-thickness ratio (the ratio of the width to the thickness of the plate element) increases, along with the effective cross-section that can resist the load. However, this decrease can be suppressed by adding lip 7. In other words, it is possible to make the cross-section function efficiently even when the wall thickness is reduced. Therefore, regardless of the embodiment, it is preferable to add lip 7 to relatively thin cross-sections, for example, with a plate thickness of 9 mm or less.

[0031] Furthermore, in the structural steel section 1 according to Embodiment 1, it is preferable that the width C of the lip 7 is equal to or greater than the required lip width Cmin, which can be determined by the following formula (1). This is because an appropriate lip width C can be selected according to the side width B, plate thickness t, and material of the structural steel section 1. The required lip width here refers to the required lip length described in "National Institute for Land and Infrastructure Management (supervised), Building Research Institute (supervised), Japan Iron and Steel Federation (ed.). Handbook for Design of Lightweight Steel Sections Buildings. 2nd Edition, Gihodo Publishing, 2014, p. 83," which is calculated from the following formula.

[0032]

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[0033] The material used for the structural steel section 1 according to Embodiment 1 is not particularly limited, but it is preferable to use corrosion-resistant steel or to apply a surface treatment that improves corrosion resistance, as this can further improve maintainability.

[0034] In manufacturing the structural steel section 1 according to Embodiment 1, any cross-section can be manufactured from flat steel plates or thin steel plate coils by utilizing press forming and cold working processes such as roll forming, which offer a high degree of freedom in forming. In this case, if a material is used in which the plate thickness of the steel plate differs within the plate surface, such as a tailored blank material, it is also possible to manufacture structural steel section 1 in which the plate thickness differs at different cross-sectional positions. When such structural steel section 1 is used as a structural member, it is preferable as it also improves the degree of design freedom. For example, making the plate thickness of the lip 7 thicker than the plate thickness of the side 5 can effectively improve buckling strength.

[0035] When the structural steel section 1 according to Embodiment 1 is applied to truss structures such as steel towers, bridges, and cranes, for example, the structural steel section 1 according to Embodiment 1 is suitable for use as a component of the truss structure of a truss structure because, despite being an open-section structure, it possesses basic structural performance such as buckling resistance and bending strength as a structural member. Furthermore, the structural steel section 1 according to Embodiment 1 is suitable for use as a member with excellent transportability (including stackability during storage and transport) because it is an open-section structure before the truss structure is constructed. Moreover, even after the truss structure is constructed, the fact that the components of the truss structure are open-section structures makes it possible to create a truss structure with high maintainability, which is preferable.

[0036] (Embodiment 2) Figure 6 is a cross-sectional view showing a structural steel section 1 according to Embodiment 2. Figure 6(a) shows a structural steel section 1 with a side angle θ1 greater than 90° and 120° or less, and Figure 6(b) shows a structural steel section 1 with a side angle θ1 of 60° or more and less than 90°. The structural steel section 1 according to Embodiment 2 will be described below with reference to Figure 6.

[0037] As shown in Figure 6, the structural steel section 1 according to Embodiment 2 is provided with an in-edge bend 5c at a predetermined length from the tip of each of the two sides 5, dividing the side 5 into a first side 5a on the side corner 3 side and a second side 5b on the tip side. The bending angle of the in-edge bend 5c is set to a bending angle where the extensions of the two second sides 5b are approximately perpendicular to each other, while maintaining the side angle θ1 and lip angle θ2, and the second side 5b serves as the member connecting part. The other configurations are the same as in Embodiment 1. As mentioned above, the required lip width Cmin is relative to the width B of the plate element of the side that is directly in contact with the lip, so the required lip width Cmin according to Embodiment 2 may also be calculated relative to the second side 5b. In this case, the second side 5b will naturally be shorter than the length of the side 5, so the required lip width Cmin will also be smaller.

[0038] Figure 7 illustrates (c) and (d) examples in which the structural steel section 1 according to Embodiment 2 is applied to a power transmission tower 20 shown in (a), which is a representative example of a truss structure, comparing it with (b) an example in which the structural steel section 1 according to Embodiment 1 is also applied to a power transmission tower 20, using a schematic horizontal cross-sectional view that shows an enlarged view of the structural steel section 1 as seen from the AA cross-section in (a). As shown in Figures 7(c) and (d), the structural steel section 1 according to Embodiment 2 has a member connection portion (second side) 5b (see Figure 6) that is substantially perpendicular in cross-section, which is preferable when used as a support column for a structure with a rectangular horizontal cross-section, such as the support column (main column member) 22 of a power transmission tower 20, as it facilitates connection with other members such as horizontal members 24 and diagonal members 26, such as web members 28, similar to the structural steel section 1 with a side angle θ1 of 90° in Figure 7(b).

[0039] Furthermore, the structural steel section 1 according to Embodiment 2, in which the side angle θ1 is greater than 90° and less than or equal to 120°, has a wider opening 9 compared to the structural steel section 1 with a side angle θ1 of 90° or less. This not only improves the maintainability of the structure, but also improves transportability by lowering the center of gravity of the structural steel section 1 in the stacking direction, resulting in a more stable load.

[0040] On the other hand, the structural steel section 1 according to Embodiment 2, in which the side angle θ1 is 60° or more and less than 90°, is preferable because, compared to the structural steel section 1 in which the side angle θ1 is 90° or more, the second moment of area of ​​the weak axis is larger, and the basic structural performance as a structural member is improved. [Explanation of symbols]

[0041] 1 Structural steel sections 3 side corner 5 side 5a 1st side 5b Second side (member connection part) 5c Inner bend 7 Lip 9 Opening 20 Power transmission towers 22 Pillar (main pillar material) 24 Horizontal material 26 Diagonal 28 Belly material 50 Building Columns Side wall panels 51, 52, 53, 54 55 Opening

Claims

1. A cross-section perpendicular to the longitudinal direction, (a) It is mountain-shaped, (b) The widths B of the sides on both sides are approximately equal, (c) The side angle θ1 formed by the two sides is 60° or more and 120° or less, (d) Lips symmetrical with respect to the strong axis of the mountain-shaped cross-section are added to the ends of each of the two sides, Structural steel sections, The lip has a width C shorter than the width B of the side edge, and is inclined toward the side extending from the side edge towards the side edge angle, with a lip angle θ2 greater than 0° and less than or equal to the side edge angle θ1. A structural steel section comprising: a first side on the corner side and a second side on the tip side, wherein the bending angle of the inward bending portion is set such that the extensions of the two second sides are substantially perpendicular to each other, while maintaining the side angle θ1 and the lip angle θ2, and the second side serves as a member connecting portion.

2. A cross-section perpendicular to the longitudinal direction, (a) It is mountain-shaped, (b) The widths B of the sides on both sides are approximately equal, (c) The side angle θ1 formed by the two sides is 60° or more and 120° or less, (d) Lips symmetrical with respect to the strong axis of the mountain-shaped cross-section are added to the ends of each of the two sides, Structural steel sections, The aforementioned lip is (e) Having a width C shorter than the width B of the side, (f) The lip angle θ2 that slopes toward the sides approaching each other across the side angle from the extension of the side edge is (f1) greater than 0°, and (f2) An angle smaller than the angle at which the lip is substantially perpendicular to the weak axis of the cross-section of the structural steel section, Structural steel sections.

3. The structural steel section according to claim 1 or claim 2, wherein the width C of the lip is greater than or equal to the required lip width Cmin, which is calculated by the following formula (1). [Math 1] Here, Cmin: Required lip width (mm), B: Width (mm) of the side plate element that is in direct contact with the lip. t: plate thickness (mm), F: F value (standard strength (N / mm²) determined by the Minister of Land, Infrastructure, Transport and Tourism according to the type and quality of steel materials, etc.) ２ ). See Article 90 of the Building Standards Act Enforcement Order, etc.) The yield strength shall be the smaller of the yield point and 70% of the tensile strength.

4. A truss structure comprising structural steel shapes as described in any one of claims 1 to 3.

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