JP6638577B2 - Buckling stiffening structure and section steel - Google Patents

Description

  The present invention relates to a buckling stiffening structure provided on a plate element having a predetermined cross-sectional shape, and to a shaped steel provided with a buckling stiffening structure for a plate element having a predetermined cross-sectional shape.

  Conventionally, a buckling stiffening structure disclosed in Patent Document 1 has been used as a box-shaped cross-sectional thin plate member used for a column member of a steel house, which has a simple structure, a relatively easy manufacturing process, and significantly improved strength. Has been proposed. Further, a channel steel disclosed in Patent Literature 2 has been proposed as having a high member strength that cannot be obtained by a conventional channel steel or a channel steel with an inner stiffening rib.

  The buckling stiffening structure disclosed in Patent Literature 1 is a buckling stiffening structure of a box-shaped cross-section thin plate member used for a column member of a steel house, a house, a factory building, or the like. Formed into a shape, and formed a plurality of buckling stiffening regions that are displaced steplessly or stepwise toward the center of the box-shaped cross section from the corner to the center at each side of the box-shaped cross section. It is characterized by the following.

  The channel steel disclosed in Patent Literature 2 has a cross-section in which a web portion of the channel steel is provided with a protruding portion in which the maximum protruding length of the web portion in the outward direction is 60% or less of the width of the flange portion. Shape. The channel steel disclosed in Patent Literature 2 is characterized in that it has a cross-sectional shape in which an overhang portion having an overhang width of 10% or more of the width of the web portion is formed as necessary.

JP 2001-329656 A JP-A-9-268701

  Here, the buckling stiffening structure disclosed in Patent Document 1 is provided on a box-shaped thin plate member having a closed cross section, and exhibits high local buckling strength with respect to a non-stiffened plate element. However, in the buckling stiffening structure disclosed in Patent Literature 1, as shown in FIG. 2A of Patent Literature 1, although each side of the box-shaped cross section is inclined from the corner to the center, Is formed of a flat plate element, there is a problem that a buckling mode occurs in which the central portion of the buckled stiffening plate element is locally rotated.

  Further, in the buckling stiffening structure disclosed in Patent Document 1, as shown in FIG. 7B of Patent Document 1, each side of the box-shaped cross section is not inclined from the corner to the center, Further, when only the rib portion protruding toward the center of the box-shaped cross section is formed, a buckling mode in which each side moves in the depth direction occurs, and the local buckling strength is reduced.

  Further, in the channel steel disclosed in Patent Literature 2, although various shapes of overhangs projecting from the web portion of the channel steel are formed, the web portion of the channel steel is continuously inserted from both sides thereof. It is not inclined in the direction. For this reason, in the channel steel disclosed in Patent Document 2, the maximum overhang length of the overhang portion needs to be a certain size in order to improve the local buckling strength. It becomes difficult to improve the local buckling strength while suppressing the member width.

  Therefore, the present invention has been devised in view of the above-described problems, and has as its object to suppress local buckling while suppressing the development width of a plate element formed with a predetermined cross-sectional shape. An object of the present invention is to provide a buckling stiffening structure and a shape steel having improved strength.

  The buckling stiffening structure according to the first invention is a buckling stiffening structure provided on a plate element having a predetermined cross-sectional shape, the intermediate plate element having a cross-sectional shape and being continuous in a width direction; A pair of side plate elements that bend and extend from both sides in the width direction of the element, and the pair of side plate elements extend in substantially the same direction from both sides in the width direction of the intermediate plate element. The direction in which the pair of side plate elements extend is an inward direction than a virtual straight line connecting the widthwise both sides of the intermediate plate element, and the intermediate plate element is formed from both sides in the width direction. An inclined portion continuously inclined in the inward direction is formed, and a rib portion protruding from the inclined portion toward an outward direction opposite to the inward direction is formed in an intermediate portion in the width direction. Features.

  A buckling stiffening structure according to a second invention is the buckling stiffening structure according to the first invention, wherein the intermediate plate element and the pair of the side plate elements have the intermediate plate element as a web and the side plate element as a flange. Shaped steel is used, and the bending angle θ between the intermediate plate element and the side plate element is less than 90 ° on both sides in the width direction of the intermediate plate element.

  A buckling stiffening structure according to a third invention is the buckling stiffening structure according to the first invention or the second invention, wherein the intermediate plate element has a protrusion height h of the rib portion from the inclined portion to a top portion where the rib portion projects most; The width dimension b up to both sides in the width direction satisfies the relationship defined by the following equation (1). Here, t is the plate thickness of the intermediate plate element.

  A buckling stiffening structure according to a fourth invention is the buckling stiffening structure according to any one of the first invention to the third invention, wherein the intermediate plate element has a top portion where the rib portion projects most from the inclined portion substantially coincides with the virtual straight line. It is arranged at a position where

  A section steel according to a fifth invention is a section steel provided with a buckling stiffening structure of a plate element formed in a predetermined cross-sectional shape, the intermediate plate element having a cross-sectional shape and being continuous in a width direction, and the intermediate plate A pair of side plate elements that bend and extend from both sides in the width direction of the element, wherein the intermediate plate element and the pair of side plate elements use the intermediate plate element as a web and the side plate element. A channel steel having a flange, a hat-shaped steel having the intermediate plate element as a flange and the side plate element as a web, or a web or a lip having the intermediate plate element as a flange and the side plate element A pair of the side plate elements are formed to extend in substantially the same direction from both sides in the width direction of the intermediate plate element, and are formed in the width direction of the intermediate plate element. A pair of the above described than a virtual straight line connecting both sides The direction in which the component plate element extends is the inward direction, and the intermediate plate element is formed with an inclined portion that is continuously inclined in the inward direction from both sides in the width direction, and the inward direction in the inward direction from the inclined portion. A rib portion protruding outward in the opposite direction is formed at an intermediate portion in the width direction.

  According to the first to fourth aspects of the present invention, the inwardly inclined portion is formed from both sides of the intermediate plate element, and the rib portion protruding outward is formed, so that the intermediate plate element is formed. It is possible to improve the local buckling strength while suppressing the developed width of the inclined portion and the rib portion developed in the width direction.

  In particular, according to the second aspect, in the channel steel having a predetermined cross-sectional shape, it is possible to suppress the development width of the intermediate plate element and to improve the local buckling strength.

  In particular, according to the third aspect, in the intermediate plate element, the protruding height up to the apex of the rib portion and the width dimension up to both side portions in the width direction satisfy the relationship defined by the above equation (1). Thus, the local buckling strength can be reliably improved.

  In particular, according to the fourth aspect, in the intermediate plate element, the top portion where the rib portion most protrudes from the inclined portion is disposed at a position substantially coinciding with the virtual straight line, thereby efficiently improving the local buckling strength. It becomes possible.

  In particular, according to the fifth invention, in any of the channel steel, the hat-shaped steel, and the Z-shaped steel having a predetermined cross-sectional shape, the expansion width of the intermediate plate element is suppressed and the local buckling strength is improved. Becomes possible.

It is a perspective view showing the buckling stiffening structure to which the present invention is applied. (A) is a top view which shows the channel steel in which the lip of the buckling stiffening structure to which this invention was applied is formed, (b) is a top view which shows the channel steel in which a lip is not formed. (A) is a top view which shows a pair of side plate elements formed substantially in parallel with the buckling stiffening structure to which the present invention is applied, and (b) is a pair of side plate elements formed so as to be separated from each other. It is a top view which shows the side part plate element of FIG. (A) is a top view which shows the rib part in which the top part is arrange | positioned outside the imaginary straight line in the buckling stiffness structure to which this invention is applied, and (b) is a top part inwardly from the imaginary straight line. It is a top view which shows the rib part in which was arrange | positioned. (A) is a plan view showing a rib portion formed in a substantially rectangular shape in a buckling stiffening structure to which the present invention is applied, and (b) is a plan view showing a rib portion formed in a substantially curved shape. It is. It is a top view which shows the channel steel in which the buckling stiffening structure is provided with the shape steel which applied this invention. It is a top view which shows the hat-shaped steel provided with the buckling stiffening structure with the shaped steel to which this invention is applied. 1 is a plan view showing a Z-section steel provided with a buckling stiffening structure using a section steel to which the present invention is applied. (A)-(d) is a top view which shows the numerical analysis model of Comparative Examples 1-4, (e) is a top view which shows the numerical analysis model of this invention example. It is a graph which shows the elastic local buckling strength per unit cross-sectional area about each model of this invention example and the comparative examples 1-4. 5 is a graph showing the relationship between the protrusion height h / width dimension b in the buckling stiffening structure to which the present invention is applied and the local buckling strength in the model of the present invention. (A) is a graph showing the relationship between the protrusion height h / width dimension b when the width dimension b / plate thickness t is changed and the local buckling strength in the model of the example of the present invention; 4 is a graph showing the relationship between width dimension b / plate thickness t and protrusion height h / width dimension b. (A) is a top view which shows the width dimension of a rib part in the buckling stiffening structure to which the present invention is applied, and (b) is a projection height when the width dimension of the rib part with respect to the intermediate plate element is changed. 7 is a graph showing the relationship between h / width dimension b and local buckling strength in the model of the present invention. (A) is a plan view showing the protrusion height of the rib portion in the buckling stiffening structure to which the present invention is applied, and (b) is a diagram showing the protrusion height of the rib portion when the protrusion height of the rib portion is changed. It is a graph which shows the relationship with local buckling strength in the model of the example of the present invention. It is a graph which shows the local buckling strength in the model of this invention example when the rib part is formed in a substantially triangular shape, a substantially rectangular shape, or a substantially circular arc shape in the buckling stiffening structure to which the present invention is applied.

  Hereinafter, embodiments for implementing a buckling stiffening structure 1 and a shaped steel 7 to which the present invention is applied will be described in detail with reference to the drawings. In FIGS. 1 to 8, the plate thickness of each plate element is shown in an enlarged manner in order to facilitate understanding of the contents of the present invention.

  The buckling stiffening structure 1 to which the present invention is applied is mainly provided on a section steel 7 such as a channel steel 71 as shown in FIG. The buckling stiffening structure 1 to which the present invention is applied is provided on a plate element having a predetermined cross-sectional shape with respect to the axial direction Z of the shaped steel 7 or the like.

  As shown in FIG. 2, the buckling stiffening structure 1 to which the present invention is applied has an intermediate plate element 2 having a cross-sectional shape in the material axis direction Z and continuous in the width direction X, and the intermediate plate element 2 in the width direction X. A pair of side plate elements 3 that bend and extend from the side portions 20. When the buckling stiffening structure 1 to which the present invention is applied is provided in the channel steel 71, the cross-sectional shape of the plate element is formed in a substantially groove shape.

  In the buckling stiffening structure 1 to which the present invention is applied, when provided on the channel steel 71, the intermediate plate element 2 is a web 7a and the side plate element 3 is a flange 7b. At this time, in the buckling stiffening structure 1 to which the present invention is applied, as shown in FIG. 2A, a lip 7c is formed at the tip of the flange 7b, and as shown in FIG. The lip 7c may not be formed. In the case where the lip 7c is formed, the lip 7c is formed by bending by bending or the like of a steel plate or the like, so that a bent portion serving as a boundary between the flange 7b and the lip 7c may be formed in a slightly curved state.

  As shown in FIG. 3, the pair of side plate elements 3 are formed to extend in substantially the same direction from both side portions 20 of the intermediate plate element 2 in the width direction X. At this time, the pair of side plate elements 3 extend substantially only to either the near side or the back side in the depth direction Y with the intermediate plate element 2 as a boundary, so that the side plate elements 3 are substantially the same from both sides 20 of the intermediate plate element 2. It extends in the direction.

  The pair of side plate elements 3 extend closer to the near side in the depth direction Y than a virtual straight line S connecting the two side portions 20 of the intermediate plate element 2 in the width direction X linearly. The direction is the inside direction α. In addition, the pair of side plate elements 3 is located on the back side in the depth direction Y, and the side opposite to the inside direction α in which the pair of side plate elements 3 extends is the outside direction β. In addition, when the illustrated intermediate plate element 2 and the side plate element 3 are reversed in the depth direction Y, the pair of side plate elements 3 is such that the depth side in the depth direction Y becomes the inside direction α, and the depth direction Y Is the outward direction β.

  As shown in FIG. 3A, the pair of side plate elements 3 extend from both side portions 20 of the intermediate plate element 2 in the same direction in the depth direction Y, and are formed substantially parallel to each other. Further, as shown in FIG. 3B, the pair of side plate elements 3 extend from both sides 20 of the intermediate plate element 2 in substantially the same direction in the depth direction Y as necessary, and It may be formed to separate or approach at X.

  The intermediate plate element 2 is formed with an inclined portion 4 that is inclined in the depth direction Y toward the inside direction α continuously from both side portions 20 in the width direction X. Further, in the intermediate plate element 2, a rib portion 5 protruding in the outer direction β opposite to the inner direction α is formed in a part of the intermediate portion 21 in the width direction X.

  The intermediate plate element 2 has an intermediate portion 21 in the width direction X at a position substantially at the center in the width direction X and at a position on the right or left side of the center in the width direction X. The intermediate plate element 2 has an inclined portion 4 formed on both sides of the rib portion 5 in the width direction X, and the rib portion 5 is mainly disposed substantially at the center of the width direction X. The rib portion 5 may be arranged at a position on the right side or the left side.

  The inclined part 4 may be formed continuously from both sides 20 of the intermediate plate element 2 to the intermediate part 21 so as to be inclined substantially linearly, or may be formed inclined substantially curved. The rib portion 5 is formed by bending the inclined portion 4 from the position that is the innermost direction α toward the outer direction β. Moreover, the rib part 5 may be formed in the inclined part 4 on the right side or the left side of the position which becomes the innermost direction α.

  The rib portion 5 has a bottom portion 51 that is bent from the inclined portion 4 toward the outer direction β, and a top portion 50 that most protrudes from the inclined portion 4 toward the outer direction β. Etc. are formed. The rib portion 5 may be formed so as to be substantially linearly inclined from the bottom portion 51 to the top portion 50, or may be formed to be substantially curvedly inclined from the bottom portion 51 to the top portion 50.

  In a part of the intermediate portion 21 of the intermediate plate element 2, since the rib portion 5 is formed by bending a steel plate or the like, the bent portion serving as the bottom portion 51 or the top portion 50 of the rib portion 5 is slightly curved. It may be formed in a state.

  The rib portion 5 is disposed at a position where the top portion 50 that protrudes most in the outward direction β substantially matches the virtual straight line S in the depth direction Y. In addition, as shown in FIG. 4A, the top part 50 of the rib part 5 may be arranged in the depth direction Y and in the outer direction β with respect to the virtual straight line S. Further, as shown in FIG. 4B, the rib portion 5 protrudes in the outer direction β from the bottom portion 51 bent from the inclined portion 4, but in the depth direction Y inside the virtual line S from the virtual straight line S. The top 50 may be located at the top.

  The rib portion 5 is mainly formed in a substantially triangular shape having the top portion 50 as an apex. Further, as shown in FIG. 5A, the rib portion 5 may be formed in a substantially linear shape from the bottom portion 51 to the top portion 50 and the top portion 50 in a substantially straight shape. As shown in b), it may be formed in a substantially curved shape in which the bottom 51 to the top 50 are curved in a substantially arc shape or the like.

  The intermediate plate element 2 and the pair of side plate elements 3 are, for example, as shown in FIG. 6, channel steel 71 having the intermediate plate element 2 as the web 7a and the side plate element 3 as the flange 7b. . At this time, the intermediate plate element 2 and the pair of side plate elements 3 are formed such that the pair of side plate elements 3 are formed substantially parallel to each other, and the inclined portions 4 are continuously formed from both side portions 20 of the intermediate plate element 2. By inclining in the inward direction α, the bending angle θ between the intermediate plate element 2 and the side plate element 3 becomes less than 90 °.

  It should be noted that the intermediate plate element 2 and the pair of side plate elements 3 can be connected to the intermediate plate element 2 and the side plate element 3 even when the pair of side plate elements 3 are formed to be separated from or approach each other in the width direction X. The bending angle θ formed by the component plate element 3 can be less than 90 °. Further, since the side plate elements 3 are bent at the both side portions 20 of the intermediate plate element 2 by bending or the like of a steel plate or the like, the bending serving as a boundary between the intermediate plate element 2 and the side plate elements 3 is formed. The portion may be formed in a slightly curved state.

  As shown in FIGS. 6 to 8, the shaped steel 7 to which the present invention is applied includes an intermediate plate element 2 that is continuous in the width direction X and a pair of bent members extending from both sides 20 of the intermediate plate element 2 in the width direction X. Side plate element 3. In the section steel 7 to which the present invention is applied, a buckling stiffening structure 1 to which the present invention is applied is provided to a channel section steel 71, a hat section steel 72, or a Z section steel 73 formed in a predetermined sectional shape. .

  The section steel 7 to which the present invention is applied is mainly provided with a buckling stiffening structure 1 to which the present invention is applied to a channel steel 71 as shown in FIG. At this time, the shaped steel 7 to which the present invention is applied has the intermediate plate element 2 and the pair of side plate elements 3 as the intermediate plate element 2 as the web 7a and the pair of side plate elements 3 with the flange 7b. Channel steel 71 is used.

  In addition, as shown in FIG. 7, the section steel 7 to which the present invention is applied is, as shown in FIG. 7, a flange 7 b continuous in the width direction X, a pair of webs 7 a extending from the flange 7 b, and extending from the pair of webs 7 a. The buckling stiffening structure 1 is provided on a hat-shaped steel 72 having a pair of arm portions 7d. At this time, the hat-shaped steel 72 having the intermediate plate element 2 as the flange 7b and the respective side plate elements 3 as the respective webs 7a is used as the section steel 7 to which the present invention is applied.

  As shown in FIG. 8, the section steel 7 to which the present invention is applied has a pair of flanges 7 b continuous in the width direction X, a web 7 a extending from the pair of flanges 7 b, and a pair of flanges 7 b, as necessary. A buckling stiffening structure 1 is provided on a Z-shaped steel 73 having a pair of lips 7c extending from the buckling stiffening structure 1. At this time, in the shaped steel 7 to which the present invention is applied, one of the pair of side plate elements 3 becomes the lip 7c and the other becomes the web 7a, the intermediate plate element 2 becomes the flange 7b, and the side plate element 3 Is used as the web 7a or the lip 7c.

  In the buckling stiffening structure 1 to which the present invention is applied, the inclined portions 4 which are inclined in the inward direction α from the both side portions 20 of the intermediate plate element 2 and the rib portions 5 which protrude in the outward direction β are formed. As a result, the local buckling strength of the plate element in the shaped steel 7 or the like is improved. Here, in order to verify the effect of improving the local buckling strength, as shown in FIG. 9, a comparison was made between the present invention example, which is a buckling stiffening structure 1 to which the present invention was applied, and Comparative Examples 1 to 4. Numerical analysis was performed.

  In this numerical analysis, in each of the present invention example and Comparative Examples 1 to 4, the compressive force in the material axis direction Z is uniformly applied to the entire cross section of the intermediate plate element 2, and the plate thickness t of the intermediate plate element 2 and A model in which both side portions 20 of the intermediate plate element 2 are supported with the width dimension b in the width direction X up to both side portions 20 being fixed. FIG. 9A shows a model of Comparative Example 1 in which the intermediate plate element 2 is not inclined in the inward direction α and the rib portion 5 is not formed. FIG. 9B shows a model of Comparative Example 2 in which the intermediate plate element 2 is not inclined in the inward direction α and the rib portion 5 protruding toward the inward direction α is formed. FIG. 9C shows a model of Comparative Example 3 in which the intermediate plate element 2 is inclined in the inward direction α but the rib portion 5 is not formed. Further, FIG. 9D shows a model of Comparative Example 4 in which the intermediate plate element 2 is inclined in the inward direction α but the rib portion 5 protruding toward the inward direction α is formed. FIG. 9E shows a model of the present invention example in which the intermediate plate element 2 is formed with a rib portion 5 that is inclined in the inward direction α and protrudes in the outward direction β.

  According to the result of the numerical analysis, as shown by the broken line, in Comparative Example 1, the entire intermediate plate element 2 is curved, and the center in the width direction X moves in the depth direction Y. In Comparative Examples 2 and 4, the intermediate plate element 2 moves in the depth direction Y at the center in the width direction X. In Comparative Example 3, the intermediate plate element 2 rotates at the center in the width direction X. On the other hand, in the example of the present invention, the intermediate plate element 2 does not move in the depth direction Y at the center in the width direction X, and the intermediate plate element 2 does not rotate at the center in the width direction X. It can be seen that the intermediate plate element 2 shows high resistance to buckling even when the load is applied.

  As shown in FIG. 10, the results of the numerical analysis show the elastic local buckling strength per unit cross-sectional area for each of the models of the present invention and Comparative Examples 1 to 4. At this time, in Comparative Examples 1 to 4, a buckling mode in which the intermediate plate element 2 moves or rotates at the center in the width direction X occurs, so that the elastic local buckling strength decreases. On the other hand, in the example of the present invention, since the intermediate plate element 2 does not move or rotate at the center in the width direction X, the elastic local buckling strength increases. The effect of improving the local buckling strength of steel was verified.

  As described above, in the buckling stiffening structure 1 to which the present invention is applied, the inclined portions 4 inclined in the inward direction α from the both side portions 20 of the intermediate plate element 2 are formed, and the ribs protruding in the outward direction β. The formation of the portion 5 makes it possible to improve the local buckling strength of a plate element such as the shaped steel 7. In addition, the buckling stiffening structure 1 to which the present invention is applied has an improved elastic local buckling strength per unit cross-sectional area and an improved elastic local buckling strength per unit extension. It is possible to improve the local buckling strength while suppressing the deployment width in which the is deployed in the width direction X.

  As shown in FIG. 6, the buckling stiffening structure 1 to which the present invention is applied has a structure from the inclined portion 4 of the intermediate plate element 2 to the top portion 50 where the rib portion 5 projects most, and from the bottom portion 51 to the top portion 50 of the rib portion 5. Is a predetermined protrusion height h in the depth direction Y. Further, in the buckling stiffening structure 1 to which the present invention is applied, the intermediate plate element 2 has a predetermined width dimension b in the width direction X up to both side portions 20 and the intermediate plate element 2 has a predetermined plate thickness t. Then, in order to verify a range in which the local buckling strength is surely improved, a desirable relationship between the protruding height h of the rib portion 5 and the width dimension b to both side portions 20 of the intermediate plate element 2 was examined.

  Here, the top 50 of the rib portion 5 is made to coincide with the virtual straight line S, and the width dimension b / plate thickness t is constant (b / t = 83), and the condition of the comparative example 2 shown in FIG. The model was compared with the model of the present invention example shown in FIG. 9E, and the same numerical analysis as in FIG. 9 was performed. According to the result of this numerical analysis, as shown in FIG. 11, when the protrusion height h / width dimension b is the horizontal axis, and the local buckling strength of the model of the present invention with respect to the model of the comparative example 2 is the vertical axis, It can be seen that the local buckling strength is reliably improved in the range of 0 <projection height h / width dimension b ≦ 0.12.

  Further, according to the result of numerical analysis in which the width dimension b / the sheet thickness t is changed, as shown in FIG. The point where the local buckling strength matches with the model of the invention example (circled portion where the vertical axis = 1) moves in the horizontal axis direction. Then, the encircled portion where the vertical axis = 1 is moved in the horizontal axis direction such that the protruding height h / the width dimension b increases as the width dimension b / the plate thickness t decreases. At this time, as shown by the solid line in FIG. 12 (b), the encircled portion where the vertical axis = 1 in FIG. 12 (a) has the width b / plate thickness t as the horizontal axis and the protrusion height h / width dimension Assuming that b is the vertical axis, it is plotted on a curve where h / b = 5.99 × (b / t) ＾ (− 0.876). The range where the local buckling strength of the present invention example is higher than that of the comparative example 2 is a region below the solid line in FIG.

  Furthermore, according to JIS G 3350, since the tolerance of the angle formed by the intermediate plate element 2 and the side plate element 3 is ± 1.5 ° or less, (b / 2) × (1.5 ° / 180 °) × π) ≦ h, and the lower limit of the protrusion height h / width dimension b is 0.0131. As described above, in the buckling stiffening structure 1 to which the present invention is applied, in the intermediate plate element 2, the protruding height h of the rib portion 5 and the width dimension b to both sides 20 of the intermediate plate element 2 are as follows ( By satisfying the relationship defined by the expression (1), the local buckling strength can be reliably improved.

Next, as shown in FIG. 13A, the same numerical analysis as in FIG. 9 was performed by changing the _{rib part} / b with the rib part 5 having a predetermined width dimension b _rib in the width direction X. According to the result of the numerical analysis, as shown in FIG. 13B, the local buckling strength of the example of the present invention is higher than that of the comparative example 2 regardless of the width b _rib of the rib portion 5. It can be seen that the range hardly changes.

  Next, as shown in FIG. 14A, the protrusion height h2 of the rib 5 is changed based on the protrusion height h of the rib 5 when the top 50 of the rib 5 coincides with the virtual straight line S. The same numerical analysis as in FIG. 9 was performed. Then, as shown in FIG. 14 (b), when (h−h2) / h is the horizontal axis and the local buckling strength at the protrusion height h2 with respect to the protrusion height h is the vertical axis, (h−h2) / h It can be seen that when ≒ 0, the local buckling strength is maximized. Therefore, in the buckling stiffening structure 1 to which the present invention is applied, the local buckling strength is obtained by arranging the top portion 50 from which the rib portion 5 projects most at a position (h2 ≒ h) substantially coinciding with the virtual straight line S. Can be efficiently improved.

  Finally, when the rib portion 5 is formed in a substantially triangular shape, as shown in FIG. 5A, when the rib portion 5 is formed in a substantially rectangular shape, and as shown in FIG. The effect of improving the local buckling strength of each case where the rib portion 5 is formed in a substantially arc shape was examined. At this time, as shown in FIG. 15, when the local buckling strength in the model of the present invention example with respect to the model of Comparative Example 2 is shown on the vertical axis, the rib portion 5 has a substantially triangular shape, a substantially rectangular shape, or a substantially circular arc shape. In any case, since the value on the vertical axis exceeds 1, it can be seen that the local buckling strength is sufficiently improved.

  The section steel 7 to which the present invention is applied is, as shown in FIGS. 6 to 8, provided with the buckling stiffening structure 1 to which the present invention is applied, so that a channel steel 71 having a predetermined cross-sectional shape is provided. In any of the hat-shaped steel 72 and the Z-shaped steel 73, it is possible to suppress the development width of the intermediate plate element 2 and to improve the local buckling strength.

  In the case of thin, lightweight steel structures such as steel houses, any one of pillars, beams, joists and other vertical and horizontal frames is mainly made of one sheet having a thickness of 0.8 mm or more and less than 2.3 mm. A channel steel 71 or the like formed by bending a thin steel plate by roll forming, press brake or the like in order to enhance the strength may be used.

  As described above, the example of the embodiment of the present invention has been described in detail. However, each of the above-described embodiments is merely an example of the embodiment for carrying out the present invention. The scope should not be construed as limiting.

1: Buckling stiffening structure 2: Intermediate plate element 20: Both sides 21: Intermediate part 3: Side plate element 4: Sloped part 5: Rib part 50: Top part 51: Bottom part 7: Shaped steel 7a: Web 7b: Flange 7c: Lip 7d: Arm 71: Channel steel 72: Hat steel 73: Z-shaped steel S: Virtual straight line α: Inside direction β: Outside direction X: Width direction Y: Depth direction Z: Material axis direction

Claims (5)

A buckling stiffening structure provided on a plate element formed with a predetermined cross-sectional shape,
An intermediate plate element having a cross-sectional shape that is continuous in the width direction, and a pair of side plate elements that bend and extend from both sides in the width direction of the intermediate plate element,
The pair of side plate elements are formed so as to extend in substantially the same direction from both sides in the width direction of the intermediate plate element, and are paired with an imaginary straight line connecting both sides in the width direction of the intermediate plate element. The direction in which the side plate elements extend is the inward direction,
The intermediate plate element is formed with an inclined portion that is continuously inclined in the inward direction from both side portions in the width direction, and a rib portion that protrudes from the inclined portion toward an outward direction opposite to the inward direction. The buckling stiffening structure characterized in that the buckling is formed at an intermediate portion in the width direction. The intermediate plate element and the pair of side plate elements are each formed by using a channel steel having the intermediate plate element as a web and the side plate element as a flange. 2. The buckling stiffening structure according to claim 1, wherein a bending angle θ between the intermediate plate element and the side plate element is less than 90 °. In the intermediate plate element, a projection height h of the rib portion from the inclined portion to a top portion where the rib portion projects most, and a width dimension b to both side portions in the width direction are defined by the following formula (1). The buckling stiffening structure according to claim 1 or 2, wherein the following relationship is satisfied.

Here, t is the plate thickness of the intermediate plate element. The seat according to any one of claims 1 to 3, wherein the intermediate plate element is arranged such that a top portion where the rib portion protrudes most from the inclined portion substantially coincides with the virtual straight line. Stiff structure. A shaped steel provided with a buckling stiffening structure of a plate element formed with a predetermined cross-sectional shape,
An intermediate plate element having a cross-sectional shape that is continuous in the width direction, and a pair of side plate elements that bend and extend from both sides in the width direction of the intermediate plate element,
The intermediate plate element and the pair of side plate elements are a channel steel having the intermediate plate element as a web and the side plate element as a flange, and the side plate element having the intermediate plate element as a flange. A hat-shaped steel having a web, or a Z-shaped steel having the intermediate plate element as a flange and the side plate element as a web or a lip is used,
The pair of side plate elements are formed so as to extend in substantially the same direction from both sides in the width direction of the intermediate plate element, and are paired with an imaginary straight line connecting both sides in the width direction of the intermediate plate element. The direction in which the side plate elements extend is the inward direction,
The intermediate plate element is formed with an inclined portion that is continuously inclined in the inward direction from both side portions in the width direction, and a rib portion that protrudes from the inclined portion toward an outward direction opposite to the inward direction. Is formed at an intermediate portion in the width direction.

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