JP2018062798A - Truss frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the robustness against seismic force of a building to which a truss frame is applied.SOLUTION: A truss frame 10 comprises: a large truss 30 that includes an upper beam material 22 having both ends supported by columns 14, a lower beam material 24 having both ends supported by the columns 14, and a large diagonal material 32 jointed to the upper beam material 22 and the lower beam material 24; and a small truss 40 that includes a middle beam material 26 arranged between the upper beam material 22 and the lower beam material 24 and having both ends supported by the columns 14, and a small diagonal material 42 jointed with the upper beam material 22 and the middle beam material 26 or the lower beam material 24 and the middle beam material 26 without overlapping the large diagonal material 32 in the same structure plane.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a truss frame.

  Patent Document 1 below discloses a configuration in which a truss beam is provided to increase the span of a steel frame.

Japanese Patent Laid-Open No. 10-212840

  In the steel frame of Patent Document 1 described above, if even one truss beam component yields during an earthquake, the strength of the steel frame may be significantly reduced.

  In view of the above fact, an object of the present invention is to ensure robustness against seismic force of a building to which a truss frame is applied.

  The truss frame according to claim 1 includes an upper beam member whose both ends are supported by columns, a lower beam member whose both ends are supported by columns, and a large diagonal member joined to the upper beam member and the lower beam member. And a large truss provided with the intermediate beam material arranged between the upper beam material and the lower beam material and supported at both ends by a column, and does not overlap the large diagonal material in the same composition plane, A small truss including an upper beam member and the middle beam member, or a lower beam member and a small oblique member joined to the middle beam member.

  In the truss frame of claim 1, the cross section of the truss frame as a whole can be made smaller by designing the truss frame to support a long-term load with a large truss as compared to the design supporting a long-term load with a small truss. The large truss has a smaller amount of deflection than the small truss and can safely support a long-term load.

  Furthermore, the truss frame of claim 1 also includes a small truss. For this reason, even if an unexpected large earthquake occurs and a part of the truss frame surrenders, the small truss with sufficient proof stress acts effectively, so that robustness can be ensured. Note that “robustness” refers to a mechanism or property that internally prevents changes due to external factors, and by ensuring robustness, the reliability of the truss frame can be increased.

  In addition, the small oblique material is only arranged on the construction surface between the upper beam material and the middle beam material, or the construction surface between the lower beam material and the middle beam material, so that the field of view of the construction surface on which only the large oblique material is arranged can be widened. can do.

  In the truss frame according to claim 2, the small diagonal member has a smaller section verification ratio with respect to the acting force and the rigidity is smaller than the large diagonal member.

  In the truss frame according to claim 2, the cross section verification ratio for the acting force of the small oblique member is smaller than that of the large oblique member. Here, the “section verification ratio” is the ratio (N / F) of the acting force (N) to the member yield strength (F). When the acting force (N) acting on the two members is the same, the larger the member proof strength (F), the smaller the cross sectional verification ratio (N / F), and when the two members have the same member proof strength (F), the acting force (N ) Is smaller, the cross sectional verification ratio (N / F) is smaller. In the state where the large truss and the small truss are healthy, the small oblique member has a smaller acting force (N) than the large oblique member, but has a relatively large member strength (F). It can be said that the cross sectional verification ratio is small.

  Therefore, even if the large diagonal material of the large truss yields, the small diagonal member of the small truss has sufficient proof stress, so that the small truss can withstand the seismic force. For this reason, the strength of the truss frame is improved. In addition, it is possible to suppress the twisting of the truss frame during an earthquake by yielding the large diagonal material earlier than the small diagonal material.

  In addition, since the small diagonal member is less rigid than the large diagonal member, it is possible to prevent the horizontal rigidity of the truss frame from becoming excessively large. For this reason, the twist of a building can be suppressed at the time of an earthquake. Furthermore, in order to balance the rigidity of the building, it is not necessary to provide a similar truss frame on the opposite side across the center of gravity of the building, and the design flexibility of the building is increased.

  The truss frame according to claim 3, wherein a cross-sectional area of the large diagonal material of the structural surface where the small diagonal material is not disposed is smaller than a cross-sectional area of the large diagonal material of the structural surface where the small diagonal material is disposed. .

  In the truss frame of claim 3, the cross-sectional area of the large diagonal member is small in the structural surface where the small diagonal member is not arranged. As a result, when a seismic force is applied to the truss frame, it is possible to yield the large diagonal material on the structural surface where the small diagonal material is not installed. For this reason, it is possible to maintain a sound structure composed of a small oblique material and a part of the large oblique material, and to improve the robustness of the truss frame against an earthquake.

  According to the truss frame according to the present invention, it is possible to ensure the robustness against the seismic force of the building to which the truss frame is applied.

It is a front elevation view showing a truss frame according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1 showing orthogonal beams joined to a truss frame according to an embodiment of the present invention. It is a front elevation view which shows the structure of the large diagonal material and the small diagonal material in the truss frame which concerns on embodiment of this invention. It is a graph which shows each deformation amount when a short-term load acts on the truss frame which concerns on embodiment of this invention, the large truss which comprises a truss frame, and a small truss at the time of an earthquake.

(Truss frame)
As shown in FIG. 1, the truss frame 10 according to the present embodiment includes a large truss 30 that is disposed over two layers that are continuous in a vertical direction in a steel building 12 and a two-layer structure in which the large truss 30 is disposed. The frame includes a small truss 40 disposed in the upper layer. End portions of the large truss 30 and the small truss 40 are joined to the column 14, and a column-free space V is formed between the columns 14 below the large truss 30.

(Large truss)
The large truss 30 includes an upper beam member 22 as an upper chord member, a lower beam member 24 as a lower chord member, and a large oblique member 32 having both ends joined to the upper beam member 22 and the lower beam member 24, respectively. ing.

  The upper beam member 22 and the lower beam member 24 are beams of the building 12 each formed of H-shaped steel, and the end portions 22E and 24E are supported by the column 14.

  A middle beam member 26 is disposed between the upper beam member 22 and the lower beam member 24. The middle beam member 26 is a beam of the building 12 formed of H-shaped steel like the upper beam member 22 and the lower beam member 24, and an intermediate portion of the large diagonal member 32 is joined. The upper beam member 22, the lower beam member 24, and the middle beam member 26 may each be a steel material having a box-type cross section.

  A plurality of large diagonal members 32 are bridged between the columns 14 between the upper beam member 22 and the lower beam member 24. Among them, the upper end portions of the large diagonal members 32 disposed at both ends are joined to the joint portion between the column 14 and the upper beam member 22. Further, the lower end portions of the large diagonal members 32 arranged at both ends are joined to the joint portion between the lower end portion of the adjacent large oblique member 32 and the lower beam member 24.

  The upper end portions of the large oblique members 32 arranged at both ends are joined to the joint portion between the upper end portion of the adjacent large oblique member 32 and the upper beam member 22. Further, the lower end portions of the large diagonal members 32 arranged at both ends are joined to the joint portion between the lower end portion of the adjacent large oblique member 32 and the lower beam member 24.

  As a result, the large diagonal member 32 has a substantially W-shaped arrangement in which the V-shaped arrangement is continuous in the horizontal direction on the construction surface surrounded by the upper beam material 22, the lower beam material 24, and the column 14. Yes. The large diagonal members 32 may be arranged so that three or more V-shaped arrangements are continued in the horizontal direction.

  2 shows a cross-sectional view taken along line 2-2 in FIG. 1 is a cross-sectional view taken along line 1-1 in FIG. As shown in FIG. 2, the upper beam member 22 is joined with an orthogonal beam 52 extending in a direction (Y direction) orthogonal to the construction surface formed by the large truss 30. In addition, an orthogonal beam 54 extending in a direction opposite to the orthogonal beam 52 when viewed from the large truss 30 is joined to the lower beam member 24. Thereby, the columnar space V below the large truss 30 is also expanded in a direction orthogonal to the large truss 30. As shown in FIG. 3, the orthogonal beam 52 is joined to a contact point where the large diagonal member 32 is joined to the upper beam member 22 and a contact point where the small oblique member 42 is joined to the upper beam member 22.

  The large diagonal member 32 includes an upper member 32U having a lower end joined to the intermediate beam member 26, a lower member 32D having an upper end joined to the intermediate beam member 26, and an upper member 32U between the upper and lower flanges of the intermediate beam member 26. A plate-shaped axial force transmission member 32M extending from the lower end of the flange to the upper end of the flange of the lower member 32D.

  The cross-sectional area of the lower member 32D is smaller than the cross-sectional area of the upper member 32U, and the distance between the flanges of the lower member 32D is smaller than the distance between the flanges of the upper member 32U. For this reason, the axial force transmission member 32M that transmits axial force between the lower flange 32D and the upper flange of the upper member 32U and between the lower member 32D and the lower flange of the upper member 32U is mutually connected to the axis CL of the lower member 32D and the upper member 32U. Is welded to the web of medium beam member 26 at an angle to the web.

  In the present embodiment, the distance between the flanges of the lower member 32D is formed to be smaller than the distance between the flanges of the upper member 32U, but the embodiment of the present invention is not limited to this. For example, the distance between the flanges of the lower member 32D and the distance between the flanges of the upper member 32U may be formed equally. In this case, by forming the plate thickness of the lower member 32D thinner than the plate thickness of the upper member 32U, the cross-sectional area of the lower member 32D can be formed smaller than the cross-sectional area of the upper member 32U.

(Small truss)
As shown in FIG. 1, the small truss 40 includes an upper beam member 22 as an upper chord member, a middle beam member 26 as a lower chord member, and a small beam whose both ends are joined to the upper beam member 22 and the middle beam member 26, respectively. The diagonal member 42 and the upper member 32U are provided.

  The small oblique material 42 is disposed on a surface equal to the surface on which the upper member 32U of the large oblique material 32 is disposed. The upper end portion of the small oblique material 42 is joined to the joint portion between the upper end portion of the adjacent small oblique material 42 and the upper beam material 22. Further, the lower end portion is joined to the joint portion between the lower end portion of the upper member 32 </ b> U and the middle beam member 26 in the large diagonal member 32.

  In other words, the upper beam member 22 is an upper chord member of the large truss 30 and an upper chord member of the small truss 40. Further, the upper member 32 </ b> U in the large diagonal member 32 is a part of the diagonal member (large oblique member 32) constituting the large truss 30 and is also an oblique member constituting the small truss 40.

  The small oblique material 42 is arranged so as to divide the trapezoidal shape surface surrounded by the upper beam material 22, the middle beam material 26 and the two upper members 32U into three triangular shape surfaces.

  As shown in FIG. 3, the small oblique member 42 includes an H-shaped steel core member 42A and a stiffening tube 42B into which the core member 42A is inserted. The stiffening tube 42B is a buckling suppressing member that suppresses the buckling of the core member 42A. Further, as will be described in detail later, the small diagonal material 42 is formed to have a smaller cross sectional verification ratio with respect to the acting force and lower rigidity than the lower member 32D in the large diagonal material 32. Note that the small oblique material 42 may be configured without the stiffening tube 42B.

(Action / Effect)
As shown in FIG. 1, the truss frame 10 according to the present embodiment includes a large truss 30 arranged over two layers that are continuous in the vertical direction. For this reason, a long-term load can be safely supported as compared with, for example, a building in which a truss is arranged in only one layer.

  As shown in FIG. 3, in the truss frame 10 according to the present embodiment, the cross-sectional area of the lower member 32D in the large diagonal member 32 is formed smaller than the cross-sectional area of the upper member 32U. For this reason, the lower member 32D has a lower yield strength than the upper member 32U.

  Further, the truss frame 10 includes a small truss 40 in addition to the large truss 30. The small diagonal member 42 in the small truss 40 has a smaller cross sectional verification ratio for the acting force than the lower member 32D.

  Therefore, among the lower member 32D, the upper member 32U of the large truss 30, and the small diagonal member 42 of the small truss 40, the sectional verification ratio of the lower member 32D is the largest, and when the seismic force is applied to the truss frame 10 The lower member 32D yields in advance. Thereby, the yielding of the upper member 32U and the small oblique member 42 constituting the small truss 40 can be delayed, and the soundness of the small truss 40 can be maintained.

  FIG. 4 shows a load / deformation curve B1 indicating the amount of deformation of the small truss 40 with respect to a horizontal force (short-term load P) due to an earthquake, a load / deformation curve B2 indicating the amount of deformation of the large truss 30, a small truss 40 and a large A load / deformation curve B3 indicating the amount of deformation of the truss frame 10 combined with the truss 30 is shown (hereinafter simply referred to as curves B1, B2, B3).

  A point C2 in the curve B2 indicates the yield point of the lower member 32D in the large diagonal member 32. When a horizontal force exceeding the yield point is applied, the lower member 32D starts plastic deformation. A point C1 in the curve B1 indicates the yield point of the small oblique material 42.

  Further, as shown by the curve B3, the truss frame 10 in which the large truss 30 and the small truss 40 are combined has a strength when both the large truss 30 and the small truss 40 have a strength when a horizontal force acts on the truss frame 10. Therefore, the load P3 at which the large diagonal member 32 (lower member 32D) yields in the large truss 30 is larger than the load P2 at which the large diagonal member 32 yields when the small truss 40 is not provided. .

  Further, even when a horizontal force exceeding the load P3 is applied to the truss frame 10, the small diagonal member 42 of the small truss 40 exhibits the proof stress. For this reason, the horizontal force that the truss frame 10 can withstand up to the load P4 at which the small diagonal material 42 yields increases.

  As described above, the truss frame 10 is provided with the large truss 30 and the small truss 40, so that the robustness is improved as compared with the configuration in which only the large truss 30 is provided.

  Further, in the truss frame 10 according to the present embodiment, the rigidity of the small diagonal member 42 is smaller than that of the lower member 32D of the large diagonal member 32, so that the horizontal rigidity of the truss frame 10 can be suppressed from being excessively increased. .

  If the horizontal rigidity of the truss frame 10 becomes too large, the position of the building's rigid center will shift and the torsion of the building during an earthquake will increase. In order to suppress this twist, for example, the truss frame 10 needs to be provided in another place (such as the opposite side of the center of gravity of the building 12). This affects the design freedom of the building 12. On the other hand, if the horizontal rigidity of the truss frame 10 does not become excessively large, the design freedom of the building is increased.

  Further, in the present embodiment, as shown in FIG. 3, the upper beam member 22 is the upper chord member of the large truss 30 and the small truss 40, and therefore, the upper beam member 22 has the large diagonal member 32 in the large truss 30. In addition to the parts to be joined, the oblique material contacts are also formed in the small truss 40 where the small oblique material 42 is joined. For this reason, compared with the case where the small truss 40 is not provided, since the number of the orthogonal beams 52 to be joined to the upper beam material 22 can be increased, it becomes easier to support the load on the upper portion of the orthogonal beams 52 shown in FIG. The width in the Y direction of the columnar space V can be secured widely.

  In addition, in this embodiment, as shown in FIG. 1, it is set as the structure by which the pillar is not standingly arranged by the upper part of the upper beam material 22, However, Embodiment of this invention is not restricted to this. For example, in the upper beam member 22, a column can be appropriately set up at a portion where the orthogonal beam 52 shown in FIG. 3 is joined. When the column is erected, the vertical load from the column can flow to the large diagonal material 32 or the small diagonal material.

  Further, in the present embodiment, as shown in FIG. 1, the small oblique member 42 is arranged only on the construction surface between the upper beam member 22 and the middle beam member 26, so that the construction surface (medium) in which only the large oblique member 32 is arranged. The field of view of the construction between the beam member 26 and the lower beam member 24 can be widened.

  In this embodiment, the small oblique member 42 is disposed on the surface between the upper beam member 22 and the middle beam member 26, but the embodiment of the present invention is not limited to this. For example, the small oblique member 42 may be disposed on the surface between the middle beam member 26 and the lower beam member 24. In this case, the configuration of the upper member 32U and the lower member 32D shown in FIG. That is, the cross-sectional area of the upper member 32U is made smaller than the cross-sectional area of the lower member 32D, thereby reducing the proof stress of the large oblique material 32 on the construction surface where the small oblique material 42 is not disposed. Even with such a configuration, the robustness of the truss frame 10 can be ensured.

  In the present embodiment, the small oblique material 42 is formed to have a lower rigidity than the lower member 32D in the large oblique material 32. However, the embodiment of the present invention is not limited to this, and the rigidity can be arbitrarily set. Even if the rigidity is arbitrarily set, the proof strength of the entire truss frame can be increased as compared with the configuration without the small truss 40.

  Further, in this embodiment, the proof strength of the lower member 32D is made smaller than the proof strength of the upper member 32U by making the cross-sectional area of the lower member 32D in the large diagonal member 32 smaller than the cross-sectional area of the upper member 32U. The form is not limited to this. Even when the cross-sectional area of the lower member 32D and the cross-sectional area of the upper member 32U are made equal, for example, by making the material strength of the lower member 32D smaller than the material strength of the lower member 32D, the proof strength of the lower member 32D can be increased. It can be made smaller than the yield strength.

10 Truss frame 14 Column 22 Upper beam material 24 Lower beam material 26 Middle beam material 30 Large truss 32 Large oblique material 40 Small truss material 42 Small oblique material

Claims (3)

A large truss comprising: an upper beam member supported at both ends by a column; a lower beam member supported by a column at both ends; and a large oblique member joined to the upper beam member and the lower beam member; ,
The middle beam material arranged between the upper beam material and the lower beam material and supported at both ends by a column, does not overlap the large diagonal material in the same construction surface, the upper beam material and the middle beam material, Or a small truss provided with a lower beam material and a small oblique material joined to the medium beam material,
Truss frame with.   The truss frame according to claim 1, wherein the small diagonal member has a smaller section verification ratio with respect to acting force and a lower rigidity than the large diagonal member.   The cross-sectional area of the large diagonal material of the construction surface where the small oblique material is not disposed is smaller than the sectional area of the large oblique material of the structural surface where the small oblique material is disposed. The truss frame described in 1.