JP5219179B1 - Circular ring reinforcement structure for structural members subjected to shear bending - Google Patents

Abstract

A structural member having flanges at both ends of a web subjected to shear bending is designed to improve the plastic deformation ability of the structural member by avoiding early web shear buckling and securing a shear yield load.
A perspective view of a typical reinforcing structure in which a structural member having flanges 2 on the upper and lower sides of a web 1 according to the present invention has a circular ring 3 attached to the web surface is shown as a perspective view in FIG. A vertical stiffener 4 is provided between the circular ring and the upper and lower flanges 2. (b) Although the balance of the in-plane stress of the web is shown in the figure, in the circular ring inner region, the compressive principal stress -σ indicated by the dotted arrow accompanying the in-plane shear is the axial force σ _c of the circular ring and the balanced solid arrow. The tension field is controlled by the tensile principal stress + σ shown, and the shear yield load of the web can be secured by becoming the tension surface from the initial application stage. Furthermore, a truss-like balance field is created by the flange surrounding the circular ring and the longitudinal stiffener. Constructed to maintain stable yield strength after shear yield and improve plastic deformation capacity.
[Selection] Figure 11

Description

  The present invention relates to a structural member having flanges at both ends of a web, and avoids early shear buckling against shearing force applied to the web after being subjected to shear bending to ensure shear yield load and yield strength after yielding. This is intended to prevent the deterioration and increase the plastic deformation capacity of the structural member. In order to achieve this, an optimum shape is proposed and a reinforcement structure as simple as possible is provided.

  In contrast to structural members that receive anti-symmetric bending moments from the end of the material, the conventional reinforcement structure intended to increase the plastic deformation capacity when yielding at the flange in the vicinity of the end of the material has been the mainstream so far. There are not many attempts to maintain the yield strength after yielding when the force is large and the web is plasticized in advance.

  Examples of increasing the plastic deformation capacity of the web against the shear force applied to structural members with a short material length include those that reinforce the web to avoid shear buckling, those that use steel with a low yield point for the web, There are some attempts to maintain the shear strength after yielding, such as devising the joint part between the end part and the center part of the structural member.

Japanese Patent Laid-Open No. 06-017507 Japanese Patent Laid-Open No. 10-220061 Japanese Patent Application Laid-Open No. 2002-173977 Japanese Patent Application Laid-Open No. 2003-064901 JP 2008-133694 A Japanese Patent Application Laid-Open No. 2011-113264 Japanese Patent Application Laid-Open No. 2011-202424

  The problem to be solved is that in the case of a structural member having protruding flanges at both ends of the web subjected to shear bending, when the web is plasticized ahead of the flange due to in-plane shearing force, It is to avoid buckling and secure a shear yield load, and to increase the plastic deformation capacity without lowering the yield strength even in the deformation transition after yielding. Further, the structural member having a continuous opening in the web is made to have the same mechanical performance.

  A circular ring is attached to the web surface to reinforce it so that the web stably reaches the yield shear load by in-plane shear. By attaching the circular ring to the metal flat plate, the compressive principal stress in the flat plate surface is received by the axial force of the circular ring member by the arch effect, and the mechanical balance governed by the tensile principal stress is maintained in the flat plate region surrounded by the circular ring. To.

  When the web is subjected to a shearing force, it gradually shifts from an initial pure shear field to a tension field that is governed by a diagonal tensile principal stress. Consider the balance of truss-like forces between the flange surrounding the circular ring and the longitudinal stiffener to balance the tensile principal stress of the web as shear deformation progresses, and improve the plastic deformation capacity without lowering the yield strength after yielding. Intended.

  By reinforcing the circular ring on the web, the inner area of the circular ring is in a tensile stress state, so even if a circular hole that is concentric with the circular ring is provided, the balance of force is not lost, and the circular ring is connected to the surrounding flange and stiffener. Thus, the shear yield load of the web having the minimum cross section on the center line of the circular hole is secured, and the shear strength is gradually increased even after yielding.

  FIG. 9 is a schematic diagram showing a balance of in-plane stresses when a circular ring frame is provided on the outer periphery of a circular metal flat plate. (a) The figure shows a case where a shearing force is applied from a circular ring frame. As the shear deformation progresses, the circular metal plate and the circular metal plate are deformed into an elliptical shape with an angle of 45 degrees as an axis. The compressive principal stress indicated by the dotted arrow accompanying the in-plane shear is balanced with the axial force of the member of the circular ring and becomes a tension field governed by the tensile principal stress indicated by the solid arrow from the initial stage of the applied force to the plastic deformation region.

  FIG. 10 is a schematic diagram showing the mechanical characteristics of a circular ring, and receiving in-plane shear corresponds to receiving a twist as shown in FIG. 10 (a), and that a circular ring is shown in FIG. Thus, even if the structural member has a rectangular cross section with low torsional rigidity, it is arc-shaped, so rotational deformation is constrained, which is equivalent to extremely high torsional rigidity. After that, the frame material is in an elastic state for a while and leads to maintenance of yield strength after yielding.

FIG. 11A is a perspective view showing a whole view of the structural member in which the web 1 sandwiched between the flanges 2 is reinforced with a circular ring 3, and a vertical stiffener 4 is provided between successive circular rings. FIG. 5B shows the balance of the in-plane stress of the web. In the inner region of the circular ring, the compression principal stress −σ accompanying the in-plane shear is governed by the member axial force σ _c of the circular ring and the balance tensile principal stress + σ. It becomes a tension field, and a stable balance of force can be secured by using a rectangular region surrounding the circular ring as a truss mechanism.

It is a typical view of a structural member in which a circular ring and a vertical stiffener are continuously arranged on a web. It is explanatory drawing about the dynamic relationship with a circular ring diameter and a vertical stiffener space | interval. It is a block diagram of the member which arrange | positions a vertical stiffener in the circular ring back surface on the web surface. It is explanatory drawing regarding the mechanical stability accompanying arrangement | positioning of a circular ring and a vertical stiffener. It is a block diagram of the member by which the horizontal stiffener parallel to an up-and-down flange is arrange | positioned. It is explanatory drawing of the reinforcement effect of the horizontal stiffener which overlaps with a circular ring upper and lower circular arc on a back surface. It is a block diagram of the structural member which has the opening part which becomes a concentric circle inside the circular ring of a web. It is explanatory drawing of the mechanical behavior of the structural member which has a circular opening continuously on a web. It is explanatory drawing regarding the balance of the in-plane shear of the circular metal flat plate enclosed by the circular ring. It is explanatory drawing of the mechanical characteristic of a circular ring, and the reinforcement effect to the flat plate which receives a shear. It is the whole view perspective view of the circular ring reinforcement member of this invention, and the balance figure of the stress in a web surface.

  FIG. 1 is a representative example of the present reinforcing structure in which circular rings 3 are arranged at equal intervals in the longitudinal direction of a member on both front and back surfaces of a web 1 and a vertical stiffener 4 is provided by connecting upper and lower flanges 2. The inner area of the web surrounded by the circular ring becomes a tension field controlled by the tensile principal stress in the oblique 45 degree direction due to in-plane shear, and a truss mechanism is formed by the upper and lower flanges surrounding the circular ring and the left and right vertical stiffeners. Ensure balance of power.

  FIG. 3 shows a circular ring 3 on the side 1 of the web and a vertical stiffener 4 on the back side adjacent to the upper and lower flanges 2 in consideration of the mechanical stability of the outer region of the circular ring. Stiffness balance is ensured by arranging the front and back alternately at regular intervals. Naturally, the rectangular region sandwiched between the longitudinal stiffeners is limited to a range in which the yield strength does not decrease with buckling.

  In FIG. 5, the circular ring 3 and the longitudinal stiffener 4 are arranged side by side on the one side 1 of the web. Configure. By connecting continuous circular rings on the web flat plate and restraining each other, the reinforcing structure is effective when the web plate thickness is thin.

  In FIG. 7, a circular ring 3 and a longitudinal stiffener 4 are arranged side by side on one side 1 of the web, and two further longitudinal stiffeners are provided so as to contact the circular ring arc on the neutral axis from the web back side. In order to balance, a circular hole 6 having an arbitrary diameter which is a concentric circle is provided in the web inside the circular ring, and a continuous opening web type structural member is formed to make the mechanical performance uniform in the longitudinal direction of the member.

  FIG. 1 shows a typical reinforcing structure of the present invention in which circular rings 3 are arranged at equal intervals in the longitudinal direction of a member on both front and back surfaces of a web 1 and vertical stiffeners 4 are provided between the circular rings. As a member cross section, we took H-1,200x300x9x36 with a web thickness of 9.0mm and H-1,200x300x6x30 with a web thickness of 6.0mm. From both sides of the web, a circular ring with a cross section of 100mmx19mm was centered by a vertical stiffener with a constant width and 4 sections It consists of

  The solid line in Fig. 2 is the analysis result of web thickness of 9.0mm and width-thickness ratio of 133. The circular ring diameter is 960mm and the member length is 80%, and the member lengths of 5,200mm, 5,600mm and 6,000mm are three solid lines. In this range, a high plastic deformation capacity is shown. When the member length exceeds this, buckling deformation proceeds in the web region outside the circular ring, and unstable behavior can be seen from an early stage after yielding.

  The dotted line in FIG. 2 is the analysis result of the web plate thickness of 6.0 mm and the width-thickness ratio of 200. The circular ring diameter is 1,020 mm and the member length is 85%, and the member length is the same as the above example. As the flat plate becomes thinner, buckling deformation is likely to occur in the web region outside the circular ring. Since the circular ring on the web surface tends to be unstable, it is necessary to give sufficient consideration to the peripheral configuration of the circular ring according to the thickness of the web.

   FIG. 3 shows that a circular ring 3 is arranged on one side 1 of the web, close to the upper and lower flanges 2 and a longitudinal stiffener 4 is arranged close to the back side to achieve mechanical stability of the outer region of the circular ring of the web. The rigidity is balanced by arranging the front and back alternately at arbitrary intervals. Depending on the web plate thickness, the cross-section of the member is H-1,200x300x4.5x30 and H-1,200x300x3.2x25. The latter is 100mmx12mm.

The three solid lines in Fig. 4 have a web thickness of 4.5mm, a width-thickness ratio of 267, and the vertical stiffener spacing on both sides of the circular ring is 1,200mm. The member lengths are 5,600mm, 6,000mm, and 6,400mm from the top to the bottom of the solid line. The corresponding analysis results are shown. The buckling load Q _cr = 410kN indicated by the arrow on the lower left side of the figure is 44% of the yield shear load Q _y = 930kN, but it can secure a shear yield load that exceeds the buckling load, and the longitudinal stiffener on both sides of the web. By shifting, the interval between successive circular rings can be slightly widened.

The three dotted lines in FIG. 4 are the analysis results according to the same member length as described above, with the web plate thickness of 3.2 mm, the width-thickness ratio of 375, and the vertical stiffener spacing on both sides of the circular ring being 1,100 mm. The buckling load Q _cr = 150kN indicated by the arrow on the lower left side of the figure is 23% of the yield shear load of Q _y = 660kN, but it reaches the shear yield load and further maintains its yield strength after yielding and deforms. . From these results, it can be seen that the elastic buckling load of the flat plate has nothing to do with the actual strength of the flat plate.

  In FIG. 5, the circular ring 3 and the longitudinal stiffener 4 are arranged side by side on one side of the web 1, and the lateral stiffener 5 is arranged from the back side of the web so as to be parallel to the upper and lower flanges and in contact with the upper and lower arcs of the circular ring. Configure. The cross-section of the member is H-1,200x300xtwx25, it is a structural member with a length of 6,000mm in five sections of 1,200mmx1,200mm, the diameter of the circular ring is 900mm and 75% of the member is slightly smaller, the cross section of the circular ring and stiffener is 100mmx12mm It is said.

  Figure 6 shows the analysis results with web thicknesses of 3.2mm, 2.3mm, and 1.6mm as three solid lines, but the web width-thickness ratio is equivalent to 375, 520, and 750 because the member is 1,200mm. However, it is possible to secure the shear yield load of the web by restraining the continuous circular ring with the lateral stiffener and connecting it with both flanges with the longitudinal stiffener, and the shear strength gradually increases after the yield and is sufficient. It can be seen that it has plastic deformation ability.

In FIG. 6, the load deformation relationship indicated by the three dotted lines is the same result as the solid line, which is displayed by expanding the deformation angle of the horizontal axis three times, and verifies the mechanical properties at the initial stage of applied force. The buckling load indicated by Q _cr is 26%, 14%, and 7% of the yield shear load Q _y , but the shear yield load indicated by the arrow in the figure is reached and the yield strength is maintained even after deformation. This fact shows that the elastic buckling load is not related to the actual strength and the mechanical properties after yield cannot be predicted.

  FIG. 7 shows that a circular ring 3 is attached to one side of the web 1 every 1,200 mm, and a longitudinal stiffener 4 is attached so as to contact the circular arc of the circular ring from the back side. A hole 6 is provided. The cross-section of the member is H-1,200x300x3.2x25 and is a structural member with a length of 6,000mm with five sections of 1,200mmx1,200mm. The diameter of the circular ring is 900mm and the cross section of the circular ring and longitudinal stiffener is 75% of the member. It is 100mmx12mm and does not reinforce around the circular hole provided in the web.

The three solid lines shown in FIG. 8 are the analysis results when the diameter of the web circular hole is set to 480 mm, 600 mm, and 720 mm, and the opening ratio with respect to the member of 1,200 mm is 40%, 50%, and 60%. For shear opening load Q _y = 660kN of non-opening web, the shear yield load converted by the minimum cross section of the web on the center line of the circular hole corresponds to 60%, 50%, 40% of the above-mentioned numerical value indicated by the arrow in the figure, After that, even if the plasticization of the web proceeds, the proof stress gradually increases.

  The three dotted lines shown in FIG. 8 are the results when circular holes having the same diameter are provided for the same reinforcing structural member as in Example 3, and are displayed so as to substantially overlap the solid line. The continuous circular rings are connected by lateral stiffeners, and the former reinforcing structure has the same result although the stiffener arrangement is different. In addition, since the deformation of the circular ring due to the shearing shifts to an elliptical shape having the major axis and the minor axis in the direction of 45 degrees obliquely, the deformation is not constrained even if the circular ring and the stiffener are in contact with each other on the arc.

Metallic material covered in this specification, yield stress of σ _y = 30kN / cm ^2, and a steel Young's modulus E = 20,500kN / cm ^2. Although it has been shown that this reinforcement structure can use commonly used ordinary steel materials, this reinforcement structure is not limited to the grade or material, and may be high or low yield point steel, It is also effective for light metal materials with low

  The structural member reinforced with the circular ring according to the present invention avoids a decrease in yield strength due to flat plate buckling by making the flat plate surface into a pure tensile stress state, and a flat plate controlled by the width-to-thickness ratio accompanying conventional buckling. It completely changes the dynamic environment. Since the member can be configured without being restricted by the web plate thickness, it is optimal as a web shear yield type structural member for vibration suppression or earthquake resistance.

  When reinforcing a circular ring against a structural member on one side of a web, a vertical or horizontal stiffener is provided on the back side of the web so that it touches the arc of the circular ring. Since it is not a reinforced structure, it may be widely used as a structural member having a very thin web.

  The circular ring reinforcing structure of the present invention can secure a shear yield load converted to the minimum web cross section on the center line of the circle even if concentric circular holes are provided inside the circular ring, and the yield strength gradually increases after yielding. Thus, the plastic deformation ability is high, the shear yield load can be changed by the diameter of the circular hole while the web thickness is the same, and it can be a vibration-damping or earthquake-resistant structural member.

1. 1. Structural member web 2. Flange of structural member Longitudinal stiffener 4. 4. Horizontal stiffener 5. Circular ring reinforcing member Web circular opening

Claims (4)

  For a structural member having flanges at both ends of the web, a circular ring and member adjacent to both flanges on one side or both sides of the web as a reinforcing structure when the web yields in advance by shearing force applied by shear bending A stiffener perpendicular to the axis is abutted at regular intervals, the web inside the circular ring is used as the tensile stress surface, and the tensile yield and the truss balance between the flange surrounding the circular ring and the stiffener provide a shear yield load determined by the web. Reinforcing structure that secures and improves the plastic deformation capacity of structural members.   For structural members with flanges at both ends of the web, as a reinforcement structure when the web yields in advance by shearing force applied by shear bending, a circular ring adjacent to both flanges on one side of the web and a member axis orthogonal The stiffener is attached at regular intervals, and the stiffener is provided on the opposite side surface so as to be perpendicular to and in contact with the arc of each circular ring on the neutral axis, and the web inside the circular ring is used as a tensile stress surface, and the tensile stress and the circular ring are connected to each other. Reinforcement structure that secures the shear yield load determined by the web and improves the plastic deformation capacity of the structural member by the truss balance between the surrounding flange and the stiffener.   For structural members with flanges at both ends of the web, as a reinforcement structure when the web yields in advance by shearing force applied by shear bending, a circular ring adjacent to both flanges on one side of the web and a member axis orthogonal The stiffener is attached at regular intervals, and a stiffener parallel to the flange is provided on the opposite side surface so as to contact the arc of each circular ring, the web inside the circular ring is used as a tensile stress surface, and the tensile stress and the circular ring are Reinforcement structure that secures the shear yield load determined by the web and improves the plastic deformation capacity of the structural member by the truss balance between the surrounding flange and the stiffener.   For a structural member having flanges at both ends of the web, a circular ring and member adjacent to both flanges on one side or both sides of the web as a reinforcing structure when the web yields in advance by shearing force applied by shear bending A stiffener that is perpendicular to the axis is attached at regular intervals, and a concentric hole that is smaller than the circular ring diameter is formed in each circular ring inner region of the web to form a continuous opening web. Reinforcement structure that ensures the shear yield load determined by, and improves the plastic deformation capacity of structural members.

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