JP6956466B2 - Steel beam and column beam joint structure - Google Patents

Description

The present invention relates to a steel beam and column-beam joint structure with stiffened ends.

When a load is applied to the steel beams that make up the structure due to an earthquake, etc., it is effective for shear buckling, and it gently restrains the local buckling of the flange to ensure deformation ability and excessive resistance. The one described in Patent Document 1 is known as an example of a steel beam-beam joint structure capable of suppressing an increase.
In the steel beam described in Patent Document 1, the end of the steel beam having an H-shaped cross section is stiffened by a stiffening member, and the stiffening member is provided on the web at the end of the steel beam. It is composed of vertical stiffeners orthogonal to the longitudinal direction of the steel frame beam, and the upper and lower ends of the vertical stiffeners are not joined to the flanges of the steel frame beam.

In addition, by stiffening the web with a lateral stiffener to increase the bending strength, the lateral stiffener suppresses the occurrence of local buckling of the web and prevents premature loss of yield strength. As an example of the structure, the one described in Patent Document 2 is known.
The stiffening structure of the hybrid H-section steel beam described in Patent Document 2 includes a flange plate yield strength ff, a web plate yield strength fw, and a flange plate relating to the central axis of the web height h of the hybrid H-section steel. The relationship between the cross-sectional coefficient Zf and the cross-sectional coefficient Zw of the web plate is expressed by a function that satisfies the relationship defined by a predetermined formula, and the web plate is joined to the column material with a stiffener attached to the beam end. It is characterized by being stiffened.

In addition, the proof stress deterioration due to the local buckling deformation of the compression flange is supplemented by the reinforcing portion arranged near the neutral axis of the member cross section of the structural member, so that the structural member can be prevented from suddenly deteriorating in proof stress. The one described in Patent Document 3 is known as an example of a reinforcing structure of a structural member for ensuring stable deformation performance. The reinforcing structure described in Patent Document 3 is provided on the compression side of the flange by plasticization in the vicinity of the neutral axis of the member cross section of the structural member in a predetermined section including a section in which plasticization due to bending and twisting deformation of the flange is considered. It is characterized in that a reinforcing portion having a predetermined cross section is provided in parallel with the flange to compensate for the deterioration of the bending strength of the flange.

Japanese Unexamined Patent Publication No. 2014-51822 Japanese Unexamined Patent Publication No. 2015-105543 Japanese Unexamined Patent Publication No. 6-17507

By the way, it is an H-shaped cross-section beam with a large cross section and high strength used in super high-rise buildings, large distribution warehouses, etc., and can achieve both reduction of member weight and improvement of cross section efficiency (bending rigidity) and bending strength. In the case of a thin-walled web and a welded-assembled H-shaped cross-section (BH) beam using a high-strength flange for the thin-walled web, the proof stress of the member may suddenly decrease against the horizontal external force acting due to an earthquake or the like. There is a risk of clipping corruption of the web. That is, in a BH beam in which the flange is thick and wide, the web is thin (the width-thickness ratio is large), and the yield stress of the flange is high with respect to the web, the flange at the beam end has a U-shaped curved buckling. If this occurs, since the web is thin and has low strength, the web near the compression side flange may be crushed, causing clipping failure accompanied by a sudden decrease in the load bearing capacity of the member.

On the other hand, like the steel beam described in Patent Document 1, the web at the beam end is stiffened by using a vertical stiffener extending in a direction orthogonal to the axial direction of the beam and a horizontal stiffener extending in the axial direction of the beam in combination. Even in such a case, there is a possibility that clipping failure may occur in a beam having an H-shaped cross section made of a steel material having a high degree of yield stress of the flange with respect to the web.

Further, in the stiffening structure of the hybrid H-shaped steel beam described in Patent Document 2, a horizontal stiffener is installed for the purpose of reinforcing the bending strength of the low-strength web, but a vertical stiffener for preventing clipping fracture of the web is installed. Therefore, in a beam having an H-shaped cross section made of a steel material having a high degree of yield stress of the flange with respect to the web, clipping fracture may occur.

Further, in the reinforcing structure of the structural member described in Patent Document 3, when a bending moment acts on the beam, in order to compensate for the decrease in proof stress due to the torsional buckling of the beam flange on the compression side, it is located near the neutral axis (center) of the web. Although various types of stiffeners are installed, it is not expected to have an effect on the clipping failure of the web. Clipping breakage may occur. Further, FIG. 8 of Patent Document 3 discloses that a reinforcing material made of a strip is horizontally attached to an H-shaped steel beam and vertical ribs are provided on the web at predetermined intervals. The force is provided so that the force is better transmitted from the web to the reinforcing material, and the effect on the clipping failure of the web as described above cannot be expected.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steel beam and column-beam joint structure capable of suppressing clipping fracture of a web against a horizontal external force acting due to an earthquake or the like.

In order to achieve the above object, the steel beam of the present invention is a steel beam in which the beam end of an H-shaped cross-section beam made of a steel material having a high degree of yield stress of the flange with respect to the web is stiffened.
The web at the end of the beam is provided with a plurality of vertical stiffening members that are orthogonal to the axial direction of the beam and are arranged at predetermined intervals in the axial direction.

Here, in order to stiffen the beam end portion, the stiffening length (Ls) for providing a plurality of vertical stiffening members at the beam end portion is assumed to be plasticized due to an earthquake or the like. It may be greater than or equal to the range. For example, if the inner span of the column is L,
It may be good if Ls ≧ 0.1L.

In the present invention, since the web at the beam end is provided with a plurality of vertical stiffeners orthogonal to the axial direction of the beam and arranged at predetermined intervals in the axial direction, these plurality of vertical stiffeners are provided. The member stiffens so as to constrain the out-of-plane deformation that occurs in the web at the beam end. As a result, it is possible to suppress clipping fracture of the web accompanied by a sharp decrease in the proof stress of the member due to local buckling of the flange at the beam end on the bending compression side.
Further, the vertical stiffening member provided on the web at the beam end gently restrains the flange via the web and allows local buckling that occurs on the flange, resulting in the plasticization of the beam end. It is possible to impart excellent plastic deformation performance while suppressing breakage of the beam end welded portion and a sudden decrease in load bearing capacity due to an excessive increase in proof stress.

Further, in the above-mentioned configuration of the present invention, assuming that the flange width is B,
It is preferable that at least one of the plurality of vertical stiffening members is provided at a distance of 2.0 B or less from the beam end portion.

Here, the distance from the beam end portion of the vertical stiffening member is set in this way when all of the plurality of vertical stiffening members are provided at a distance exceeding 2.0B from the beam end portion. This is because the out-of-plane deformation that occurs in the web at the beam end cannot be effectively restrained, and there is a possibility that clipping fracture of the web may occur.
Further, the distance of at least one vertical stiffening member from the beam end portion is preferably set to 50 mm or more from the viewpoint of manufacturing when the beam end portion is joined to a column or the like.

According to such a configuration, since at least one of the plurality of vertical stiffeners is provided at a distance of 2.0 B or less from the beam end, local buckling of the flange of the beam end on the bending compression side It is possible to more reliably suppress the clipping failure of the web accompanied by the sudden decrease in the proof stress of the member due to the above.

Further, in the above-mentioned configuration of the present invention, among the vertical stiffening members, the vertical stiffening members at a distance of 2.0B or less from the beam end portion are preferably provided on both sides of the web.

According to such a configuration, the vertical stiffeners provided on both sides of the web at the beam end restrain the out-of-plane deformation that occurs on both sides of the web at the beam end, so that the clipping fracture of the web is further prevented. Can be effectively suppressed.

Further, in the configuration of the present invention, the distance between the vertically stiffening members adjacent to each other in the axial direction of the beam is preferably 2.0B or less.

Here, the reason why the distance between the vertically stiffening members adjacent to each other in the axial direction of the beam is set in this way occurs in the web at the beam end when the distance between the adjacent vertical stiffening members exceeds 2.0B. This is because the out-of-plane deformation cannot be effectively restrained and the clipping failure of the web may occur.

According to such a configuration, the distance between the vertically stiffening members adjacent to each other in the axial direction of the beam is within 2.0B, so that the plurality of vertically stiffening members cause out-of-plane deformation of the web at the beam end. Since the beam is stiffened so as to be restrained, clipping fracture of the web accompanied by a sudden decrease in the proof stress of the member due to local buckling of the flange at the beam end on the bending compression side can be suppressed more reliably.

Further, in the configuration of the present invention, it is preferable that the upper and lower ends of the vertical stiffening member are not joined to the flange, and a predetermined gap is provided between the vertical stiffening member and the flange.

Here, assuming that the predetermined gap between the upper and lower ends of the vertical stiffening member and the flange is S and the beam formation is H, 0.005 ≦ S / H ≦ 0.05 (about 10 mm ≦ S ≦ 50 mm). It is preferable to set the gap S so as to be.

According to such a configuration, the upper and lower ends of the vertical stiffening member are not joined to the flange, and a predetermined gap is provided between the vertical stiffening member and the flange. Buckling is allowed. Therefore, it is possible to gently restrain the local buckling of the flange of the steel frame beam, secure the deformation ability, and suppress an excessive increase in proof stress.

Further, in the configuration of the present invention, it is preferable that the web at the end of the beam is provided with a lateral stiffening member extending in the axial direction of the beam. That is, it is preferable that the web at the beam end is provided with not only the plurality of vertical stiffening members but also lateral stiffening members extending in the axial direction of the beam in combination. Further, a plurality of the lateral stiffening members may be arranged in parallel at the top and bottom of the web.

According to such a configuration, the web can be restrained by the vertical stiffening member and the lateral stiffening member provided on the web at the beam end, so that both local buckling and shear buckling that can occur on the web can occur. It is possible to further enhance the inhibitory effect on.

Further, the column-beam joining structure of the present invention is characterized in that the steel beam is joined to the column.

In the present invention, since the plurality of vertical stiffening members provided on the web at the beam end stiffen so as to restrain the out-of-plane deformation that occurs on the web at the beam end, the flange at the beam end on the bending compression side. It is possible to suppress clipping breakage of the web accompanied by a sudden decrease in the bearing capacity of the member due to the local buckling of the flange, and it is possible to gently restrain the local buckling of the flange to secure the deformation ability and suppress an excessive increase in the bearing capacity. The strength of the steel beam does not increase excessively. Therefore, the soundness of the column-beam joint between the steel beam and the column can be maintained.

In the configuration of the present invention, the steel frame beam includes a beam joint portion joined to the column and a beam main body portion joined to the beam joint portion via a splice plate.
The web of the beam joint portion and the web of the beam main body portion may be joined to each other while the splice plate also serves as the vertical stiffening member.

According to such a configuration, the beam joint portion and the beam main body portion can be easily and surely joined by the splice plate, and the strength of the member is sharply lowered due to the local buckling of the flange at the beam end portion on the bending compression side. It is possible to suppress the accompanying clipping destruction of the web.

Further, in the configuration of the present invention, the steel beams are joined to each other via the splice plate to the columns.
The column and the web of the steel beam may be joined to each other while the splice plate also serves as the vertical stiffening member.

According to such a configuration, the splice plate can firmly join the web of the column and the steel beam, and clipping of the web accompanied by a sharp decrease in the yield strength of the member due to the local buckling of the flange at the beam end on the bending compression side. Destruction can be suppressed.

According to the present invention, since a plurality of vertical stiffeners are provided on the web at the beam end at predetermined intervals, these vertical stiffeners restrain the out-of-plane deformation that occurs on the web at the beam end. Stiffen. Therefore, it is possible to suppress the clipping fracture of the web against the horizontal external force acting by an earthquake or the like.

The beam-column joint structure according to the first embodiment of the present invention is shown, where (a) is a side view and (b) is a sectional view taken along line AA in (a). It is a graph which shows the relationship between the beam end moment M / Mp and the member angle θ / θp by FEM analysis. A beam-column joint structure according to a second embodiment of the present invention is shown, where (a) is a side view and (b) is a sectional view taken along line AA in (a). A beam-column joint structure according to a third embodiment of the present invention is shown, where (a) is a plan view and (b) is a side view. A beam-column joint structure according to a fourth embodiment of the present invention is shown, where (a) is a plan view and (b) is a side view. A beam-column joint structure according to a fifth embodiment of the present invention is shown, where (a) is a plan view and (b) is a side view.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 shows a beam-column joint structure according to the first embodiment, (a) is a side view, and (b) is a sectional view taken along line AA in (a).

In FIGS. 1 (a) and 1 (b), reference numeral 1 indicates a steel beam. The steel beam 1 has an H-shaped cross section assembled and formed by welding steel plates, and is formed so as to connect the flanges 2 and 2 between a pair of upper and lower flanges 2 and 2 and these flanges 2 and 2. It also has a web 3.
Such a steel beam 1 is a beam having an H-shaped cross section made of a steel material having a high degree of yield stress of the flange 2 with respect to the web 3, and is particularly strong and thick when it is not stiffened as described later. In the combination of the thin / wide flange 2 and the low-strength / thin-walled (large width-thickness ratio) web 3, clipping breakage of the web 3 due to the U-shaped buckling of the flange 2 is likely to occur.

The following is an example of such a combination of the flange 2 and the web 3.
(1) Assuming that the yield stress degree (fF) of the flange and the yield stress degree (wF) of the web are taken.
fF ≧ 385N / mm ² , wF ≦ 325N / mm ² (or fF / wF ≧ 385/325).
(2) In the relationship between the inner height (d) of the web, the plate thickness (tw), and the yield stress degree (wF), d / tw ≧ 100√ (235 / wF).
(3) As the ratio of the cross-sectional area (Aw) of the web to the cross-sectional area (Af) of the flange on one side,
Af / Aw ≧ 1.0.
(4) As a ratio of the plate thickness (tw) of the web and the plate thickness (tf) of the flange,
tf / tw ≧ 3.0.

The beam end portion of the steel frame beam 1 is stiffened by a stiffening member 5. The stiffening member 5 is composed of a vertical stiffener (vertical stiffening member) 6 and a horizontal stiffener (horizontal stiffening member) 7.
The vertical stiffener 6 is provided on the web 3 at the beam end of the steel frame beam 1 and is arranged orthogonal to the axial direction of the beam (horizontal direction in FIG. 1A). Further, two vertical stiffeners 6 are provided at predetermined intervals in the axial direction of the beam.
The vertical stiffener 6 is formed of vertically long rectangular plate-shaped steel plates, and projects outward from the surface of the web 3 at a substantially right angle. Further, the vertical stiffeners 6 are welded to both sides of the web 3 at the beam end so as to face each other. That is, two pairs of vertical stiffeners 6 are provided with the web 3 in between, for a total of four.
The upper and lower ends of the vertical stiffener 6 are not joined to the flanges 2 and 2, and a predetermined gap is provided between the upper and lower ends of the vertical stiffener 6 and the flanges 2 and 2. Further, the protruding length of the vertical stiffener 6 from the web 3 is set to be equal to or less than the protruding length of the flange 2 from the web 3.
The upper and lower ends of the vertical stiffener 6 may not be joined to the flanges 2 and 2 by welding or the like, and may simply be in contact with the flanges 2 and 2.

Here, assuming that the flange width of the flange 2 is B, among the vertical stiffeners 6 and 6 adjacent to each other in the axial direction of the beam, the first vertical stiffener 6 on the side closer to the beam end portion is within 2.0 B from the beam end portion. It is provided at the distance of. That is, assuming that the distance between the beam end portion and the first vertical stiffener 6 on the side close to the beam end portion is Ls1, Ls1 ≦ 2.0B.
Further, the distance between the first vertical stiffener 6 and the second vertical stiffener 6 adjacent to each other in the axial direction of the beam is set within 2.0B. That is, assuming that the distance between the adjacent vertical stiffeners 6 and 6 is Ls2, Ls2 ≦ 2.0B.

Here, FEM analysis is performed using the stiffening number (stiffening interval) of the vertical stiffener at the beam end of the hybrid beam (a beam having an H-shaped cross section made of steel having a high degree of yield stress of the flange with respect to the web) as an analysis variable. Since it was carried out, this will be explained.
The analysis models of No. 1 to No. 3 were analyzed under the analysis conditions shown in Table 1.

Here, H (mm) is a beam, B (mm) is a flange width, tw (mm) is a web plate thickness, and tf (mm) is a vertical stiffener plate thickness.
Hereinafter, the conditions are the same for Nos. 1 to 3.
[Material properties (yield stress)] Flange: fF = 385N / mm ² , Web: wF = 325N / mm ²
[Gap between vertical stiffener and beam flange s] 30 mm

In the analysis model, only half of the in-column span is modeled in consideration of symmetry, and the web at one end of the beam member with the fixed end is stiffened by vertical stiffeners and horizontal stiffeners, and the web is stiffened by vertical stiffeners and horizontal stiffeners. The bending test type of the cantilever with the free end as the free end and the free end as the loading point is used.
The formulas for calculating the moment M at the beam end and the member angle θ are as follows.
M = P · (L / 2)
θ = δ / (L / 2)
Here, P is the loading point load, and δ is the vertical displacement of the loading point.

The analysis results are as follows.
FIG. 2 shows the relationship between the beam end moment M / Mp and the member angle θ / θp by FEM analysis. The vertical axis and the horizontal axis are standardized by the total plastic moment Mp and the elastic member angle θp corresponding to the total plastic moment, respectively. In Nos. 1 and 2 in which the vertical stiffener installation interval ls> 2.0B, a rapid decrease in proof stress was confirmed near θ / θp = 5, leading to clipping failure of the web, but the vertical stiffener installation interval ls ≦ 2. In No. 3 set to 0B, clipping fracture of the web did not occur until θ / θp = 10, and it was confirmed that the effect of suppressing the clipping fracture of the web and the improvement of the plastic deformation ability by the present invention were confirmed.
Therefore, as described above, assuming that the distance between the beam end portion and the first vertical stiffener 6 on the side close to the beam end portion is Ls1, Ls1 ≦ 2.0B and adjacent to each other in the axial direction of the beam. Assuming that the distance between the vertical first vertical stiffener 6 and the second vertical stiffener 6 is Ls2, it is defined as Ls2 ≦ 2.0B.
Further, the distance from the beam end portion to the first vertical stiffener 6 on the side close to the beam end portion is preferably set to 50 mm or more from the viewpoint of manufacturing when the beam end portion is joined to a column or the like.

Further, as an example of a H-shaped cross-section beam having a large cross section and high strength used in a skyscraper, a large distribution warehouse, etc., where H is the beam formation, it is set to about 800 mm ≦ H ≦ 2500 mm.
Further, the plate thickness (ts) of the vertical stiffener 6 may be about 0.7 ≦ tw / ts ≦ 1.5 with respect to the plate thickness (tw) of the web 3.
Further, the stiffening length (Ls) may be not more than a range in which plasticization of the beam end is expected, and may be about Ls ≧ 0.1 L or more with respect to the inner span (L) of the column.

Here, in the present embodiment, two vertical stiffeners 6 are provided at predetermined intervals in the axial direction of the beam, but three or more vertical stiffeners may be provided. When three or more vertical stiffeners are provided in this way, it is preferable to provide them at equal intervals in the section of the stiffening length (Ls), but the intervals are not necessarily limited to equal intervals. Even in such a case, if the distance between adjacent vertical stiffeners is Ls2, then Ls2 ≦ 2.0B.

The horizontal stiffener 7 is provided on the web 3 at the end of the beam and is arranged parallel to the axial direction of the beam. The horizontal stiffener 7 is formed of long rectangular plate-shaped steel plates on the left and right, and projects outward from the surface of the web 3 at a substantially right angle. Further, the horizontal stiffeners 7 are welded to both sides of the web 3 so as to face each other.
Two horizontal stiffeners 7 are arranged at the central portion of the web 3 in the vertical direction so as to sandwich the first vertical stiffener 6 on the side close to the beam end portion, and the left end portion and the pillar of the horizontal stiffener 7 on the side close to the beam end portion. A gap is provided between 10 and 10 in order to absorb dimensional errors that occur in manufacturing and construction, and from the viewpoint of manufacturability and workability, and the right end portion of the lateral stiffener 7 is on the side closer to the beam end portion. The first vertical stiffener 6 is brought into contact with the central portion in the vertical direction, or is joined by welding or the like. Further, the left end of the horizontal stiffener 7 on the side far from the beam end is abutted on the vertical center of the first vertical stiffener 6 on the side close to the beam end, or is joined by welding or the like, and the horizontal stiffener is joined. The right end portion of No. 7 is in contact with the vertical center portion of the second vertical stiffener 6 on the side far from the beam end portion, or is joined by welding or the like. As described above, a total of four horizontal stiffeners 7 are provided at the end of the web 3 with the web 3 interposed therebetween.
Further, the protruding length of the horizontal stiffener 7 from the web 3 is set to be equal to the protruding length of the vertical stiffener 6 from the web 3.

The steel beam 1 having the above structure is joined to the column 10. The column 10 may have any structure, but in the present embodiment, it is composed of, for example, a cylindrical steel pipe column 10. Then, the end portion of the steel frame beam 1 is directly joined to the outer surface of the column 10 by welding or the like, or is joined by welding or bolt joining or the like via a joint portion formed in the column 10.
The columns to which the steel columns 10 are joined include not only steel columns having a cross-sectional shape such as H-shaped, box-shaped, and circular, but also concrete-filled steel pipe columns in which concrete is filled inside a box-shaped or circular steel pipe. Steel-framed reinforced concrete columns, etc. are desirable.

According to the present embodiment, a plurality of (two) vertical stiffeners (vertical stiffeners) 6 are arranged on the web 3 at the beam end at a predetermined interval in the axial direction of the beam and orthogonal to the axial direction of the beam. The plurality of vertical stiffeners 6 are stiffened so as to restrain the out-of-plane deformation that occurs in the web 3 at the beam end. As a result, clipping fracture of the web accompanied by a sudden decrease in the proof stress of the member due to local buckling of the flange 2 at the beam end on the bending compression side can be suppressed, and further, vertical columns provided on both sides of the web 3 at the beam end. Since the stiffener 6 restrains the out-of-plane deformation that occurs on both sides of the web 3 at the beam end, the clipping fracture of the web 3 can be suppressed more effectively.

Further, the vertical stiffener 6 and the horizontal stiffener 7 provided on the web 3 at the beam end gently restrain the flange 2 via the web 3 and allow local buckling to occur on the flange 2, resulting in the beam. It is possible to impart excellent plastic deformation performance while suppressing a sudden decrease in load bearing capacity due to breakage of the beam end welded portion due to an excessive increase in proof stress after plasticization of the end portion. Therefore, the soundness of the beam-column joint between the steel beam 1 and the column 10 can be maintained.
Further, in the steel frame beam 1 and the column-beam joint structure having such a configuration, since the stiffening member 5 provided on the web 3 at the beam end is composed of the vertical stiffener 6 and the horizontal stiffener 7, these stiffeners 6 , 7 can be used in combination to enhance the inhibitory effect of Web 3 on both local buckling and shear buckling.

Further, since the first vertical stiffener 6 on the side of the vertical stiffeners 6 and 6 closer to the beam end is provided at a distance of 2.0 B or less from the beam end, the flange of the beam end on the bending compression side It is possible to more reliably suppress clipping breakage of the web accompanied by a sudden decrease in the yield strength of the member due to local buckling.
Further, since the distance between the vertical stiffeners 6 and 6 adjacent to each other in the axial direction of the beam is within 2.0B, the vertical stiffeners 6 and 6 are stiffened so as to restrain the out-of-plane deformation occurring in the web at the beam end. do. Therefore, it is possible to more reliably suppress the clipping fracture of the web accompanied by the sudden decrease in the proof stress of the member due to the local buckling of the flange at the beam end portion on the bending compression side.

(Second Embodiment)
3A and 3B show a beam-column joint structure according to a second embodiment, where FIG. 3A is a side view and FIG. 3B is a sectional view taken along line AA in FIG. 3A.
The difference between the steel beam 1 shown in this figure and the steel beam 1 of the first embodiment is that four horizontal stiffeners 7 are arranged on both sides of the web 3, and the other configurations are shown in the figure. Since it is the same as that shown in 1, the common parts are designated by the same reference numerals and the description thereof will be omitted.
In the present embodiment, the two horizontal stiffeners 7 and 7, which are arranged in the axial direction of the beam on both sides of the web 3, are vertically separated from each other and arranged in parallel. On both sides of the web 3, four horizontal stiffeners 7 and 7 are provided at positions where the vertical length of the web 3 is divided into three equal parts, so that a total of eight horizontal stiffeners 7 are provided.
In the steel frame beam 1 and the column-beam joint structure having such a configuration, the same effect as that of the steel frame beam 1 and the column-beam joint structure can be obtained, and four horizontal stiffeners 7 are provided on both sides of the web 3, for a total of eight. Therefore, the effect of the web 3 on local buckling and shear buckling is greater than that shown in FIG.

(Third Embodiment)
4A and 4B show a beam-column joint structure according to a third embodiment, where FIG. 4A is a plan view and FIG. 4B is a side view.
The same reference numerals are given to the configurations common to the beam-column joint structures shown in FIGS. 1 and 3, and the description thereof will be omitted or simplified.

In the present embodiment, the steel beam 1 is a beam joint portion 1a joined to the column 10 by welding or the like, and a beam main body joined to the beam joint portion 1a via a splice plate 15 and a flange joining member 16. It includes a part 1b.
The beam joint portion 1a and the beam main body portion 1b are joined by a flange joining member 16 and a splice plate 15 in a state where the flanges 2a and 2b and the webs 3a and 3b are butted against each other.
The flanges 2a and 2b are sandwiched between the upper and lower flange joining members 16 and 16 and then bolted together, and the webs 3a and 3b are sandwiched between the front and back splice plates 15 and 15 and then bolted together. In the present embodiment, the flanges 2a and 2b form the flange 2 of the steel frame beam 1, and the webs 3a and 3b form the web 3 of the steel frame beam 1.

Further, the splice plate 15 is in a state of also serving as a vertical stiffening member, and joins the web 3a of the beam joint portion 1a and the web 3b of the beam main body portion 1b to each other. That is, in the present embodiment, the first vertical stiffener 6 shown in FIG. 1 is substituted by the splice plate 15, and the end portion of the steel frame beam 1 is formed by the splice plate 15 as the vertical stiffener and the vertical stiffener 6. It is stiffened by the horizontal stiffener 7.
Further, assuming that the flange widths of the flanges 2a and 2b are B, the splice plate 15 is provided at a distance within 2.0B from the beam end portion. That is, assuming that the distance between the beam end portion and the central portion of the splice plate 15 (the central portion in the axial direction of the beam) is Ls1, Ls1 ≦ 2.0B.
The distance between the central portion of the splice plate 15 and the second vertical stiffener 6 is set within 2.0B. That is, assuming that the distance between the central portion of the splice plate 15 and the second vertical stiffener 6 is Ls2, Ls2 ≦ 2.0B.
Further, the upper and lower ends of the splice plate 15 are not joined to the flanges 2a and 2b, and a predetermined gap is provided between the upper and lower ends of the splice plate 15 and the flanges 2a and 2b.

Further, two horizontal stiffeners 7 and 7 are arranged in parallel on both sides of the web 3a of the beam joint portion 1a so as to be vertically separated from each other. A gap is provided between the right end portion of No. 7 and the splice plate 15 in order to absorb dimensional errors that occur in manufacturing and construction, and from the viewpoint of manufacturability and workability.
Further, two horizontal stiffeners 7 and 7 are vertically separated and arranged in parallel on both sides of the web 3b of the beam main body 1b, and a gap is provided between the left end portion of the horizontal stiffener 7 and the splice plate 15. Is provided. Further, the right end portion of the horizontal stiffener 7 is brought into contact with the vertical stiffener 6 or joined by welding or the like.

According to the present embodiment, the splice plate 15 can easily and surely join the beam joint portion 1a and the beam body portion 1b, and the surface where the splice plate 15 and the vertical stiffener 6 are generated on the web 3 at the beam end portion. Since it is stiffened so as to restrain the external deformation, it is possible to suppress the clipping fracture of the web accompanied by a sudden decrease in the proof stress of the member due to the local buckling of the flange 2 at the beam end on the bending compression side.

Further, in order to allow the splice plate 15, the vertical stiffener 6 and the horizontal stiffener 7 provided on the web 3 at the beam end to gently restrain the flange 2 via the web 3 and allow local buckling to occur in the flange 2. As a result, excellent plastic deformation performance can be imparted while suppressing breakage of the beam end welded portion and a sudden decrease in load bearing capacity due to an excessive increase in proof stress after plasticization of the beam end portion.
Therefore, the soundness of the beam-column joint between the steel beam 1 and the column 10 can be maintained.
Further, in the steel frame beam 1 and the column-beam joint structure having such a configuration, the stiffening member 5 provided on the web 3 at the beam end is composed of the splice plate 15, the vertical stiffener 6, and the horizontal stiffener 7. The combined use of these splice plates 15 and stiffeners 6 and 7 can enhance the inhibitory effect of the web 3 on both local buckling and shear buckling.

(Fourth Embodiment)
5A and 5B show a beam-column joint structure according to a fourth embodiment, where FIG. 5A is a plan view and FIG. 5B is a side view.
The same reference numerals are given to the configurations common to the beam-column joint structures shown in FIGS. 1, 3 and 4, and the description thereof will be omitted or simplified.

In the present embodiment, the steel beam 1 has a beam joint portion 1c joined to the column 10 by welding or the like, and a beam main body joined to the beam joint portion 1c via a splice plate 15 and a flange joining member 16. It includes a part 1d.
In the third embodiment, the beam end portion of the steel frame beam 1 is formed by the beam joint portion 1a and the end portion of the beam body portion 1b, whereas in the present embodiment, the beam joint portion 1c constitutes the beam end portion. The beam end portion of the steel frame beam 1 is configured. Therefore, the beam joint portion 1c in the present embodiment has a longer axial length than the beam joint portion 1a in the third embodiment.

The beam joint portion 1c and the beam main body portion 1b are joined by a flange joining member 16 and a splice plate 15 in a state where the flanges 2c and 2d and the webs 3c and 3d are butted against each other.
The flanges 2c and 2d are sandwiched between the upper and lower flange joining members 16 and 16 and then bolted together, and the webs 3c and 3d are sandwiched between the front and back splice plates 15 and 15 and then bolted together. In the present embodiment, the flanges 2c and 2d form the flange 2 of the steel frame beam 1, and the webs 3c and 3d form the web 3 of the steel frame beam 1.

Further, the splice plate 15 is in a state of also serving as a vertical stiffening member, and joins the web 3c of the beam joint portion 1c and the web 3d of the beam main body portion 1d to each other. That is, in the present embodiment, the second vertical stiffener 6 shown in FIG. 1 is substituted by the splice plate 15, and the end portion of the steel frame beam 1 is formed by the splice plate 15 and the vertical stiffener 6 as vertical stiffeners. It is stiffened by the horizontal stiffener 7.

Further, assuming that the flange widths of the flanges 2c and 2d are B, the first vertical stiffener 6 is provided at a distance within 2.0B from the beam end portion. That is, assuming that the distance between the beam end and the first vertical stiffener 6 is Ls1, Ls1 ≦ 2.0B.
The distance between the first vertical stiffener 6 and the central portion of the splice plate 15 is set within 2.0B. That is, assuming that the distance between the first vertical stiffener 6 and the central portion of the splice plate 15 is Ls2, Ls2 ≦ 2.0B.
Further, the upper and lower ends of the splice plate 15 are not joined to the flanges 2c and 2d, and a predetermined gap is provided between the upper and lower ends of the splice plate 15 and the flanges 2c and 2d.

Further, two horizontal stiffeners 7 and 7, which are arranged in the axial direction of the beam on both sides of the web 3c, are vertically separated from each other and arranged in parallel. Four horizontal stiffeners 7 and 7 are provided at positions where the upper and lower lengths of the web 3 are divided into three equal parts.
In the axial direction of the beam, two horizontal stiffeners 7 are arranged so as to sandwich the vertical stiffener 6, and between the left end portion of the horizontal stiffener 7 on the side close to the beam end portion and the column 10, in terms of production and construction. A gap is provided in order to absorb the dimensional error caused by the above, and from the viewpoint of manufacturability and workability, and the right end portion of the horizontal stiffener 7 is brought into contact with the vertical stiffener 6 or joined by welding or the like. Further, the left end portion of the horizontal stiffener 7 on the side far from the beam end portion is brought into contact with the vertical stiffener 6 or joined by welding or the like, and between the right end portion of the horizontal stiffener 7 and the splice plate 15. A gap is provided in order to absorb dimensional errors that occur in manufacturing and construction, and from the viewpoint of manufacturability and workability.

According to the present embodiment, similarly to the third embodiment, the splice plate 15 can easily and surely join the beam joint portion 1c and the beam body portion 1d, and the vertical stiffener 6 and the splice plate 15 Is stiffened so as to restrain the out-of-plane deformation that occurs in the web 3c at the beam end. Can be suppressed.

Further, the splice plate 15, the vertical stiffener 6 and the horizontal stiffener 7 provided on the web 3 (3c) at the beam end gently restrain the flange 2 via the web 3 to prevent local buckling occurring on the flange 2. As a result, excellent plastic deformation performance can be imparted while suppressing breakage of the beam end welded portion and a sudden decrease in load bearing capacity due to an excessive increase in proof stress after plasticization of the beam end portion.
Therefore, the soundness of the beam-column joint between the steel beam 1 and the column 10 can be maintained.
Further, in the steel frame beam 1 and the column-beam joint structure having such a configuration, the stiffening member 5 provided on the web 3 at the beam end is composed of the splice plate 15, the vertical stiffener 6, and the horizontal stiffener 7. The combined use of these splice plates 15 and stiffeners 6 and 7 can enhance the inhibitory effect of the web 3 on both local buckling and shear buckling.

(Fifth Embodiment)
6A and 6B show a beam-column joint structure according to a fifth embodiment, where FIG. 6A is a plan view and FIG. 6B is a side view.
The difference between the steel beam 1 shown in this figure and the steel beam 1 shown in FIG. 3 is that the end portion of the web 3 of the steel beam 1 is joined to the column 10 by the splice plate 15a, and the other configurations are shown in FIG. Since it is the same as that shown in 3, the common parts are designated by the same reference numerals and the description thereof will be omitted.

The width of the splice plate 15a in the axial direction of the beam is approximately half the length of the splice plate 15, and the splice plate 15a is bolted to the web 3 on one side of the web 3. Further, the splice plate 15a is joined to the pillar 10 by welding or the like at a construction site.
The steel frame beam 1 and the column-beam joining structure having such a configuration have an advantage that the same effect as that of the second embodiment can be obtained and that the column 10 and the steel frame beam 1 can be firmly joined.

Although the examples of the embodiments of the present invention have been described in detail above, all of the above-described embodiments are merely examples of the embodiment of the present invention, and the technical aspects of the present invention are based on these. The scope should not be construed in a limited way.

1 Steel beam 1a, 1c Beam joint 1b, 1d Beam body 2,2a, 2b, 2c, 2d Flange 3,3a, 3b, 3c, 3d Web 5 Stiffening member 6 Vertical stiffener (vertical stiffener)
7 Horizontal stiffener (horizontal stiffener)
10 columns 15 splice plates 16 flange joint members

Claims (8)

For a beam with an H-shaped cross section of a welded assembly made of a steel material having a high degree of yield stress of the flange with respect to the web, a stiffening member for suppressing clipping failure of the web due to U-shaped buckling of the flange at the beam end is provided. It is a steel beam that has
The stiffening member has a plurality of vertical stiffening members on the web at the beam end, which are orthogonal to the axial direction of the beam and are arranged at predetermined intervals in the axial direction.
If the flange width is B,
At least one of the plurality of vertical stiffening members is provided at a distance of 1.9B or less from the beam end portion, so that the stiffening member suppresses clipping fracture of the web. Steel beam. The steel frame beam according to claim 1, wherein among the vertical stiffening members, the vertical stiffening members at a distance of 1.9B or less from the beam end portion are provided on both sides of the web. If the flange width is B,
The steel frame beam according to claim 1 or 2, wherein the distance between the vertically stiffening members adjacent to each other in the axial direction of the beam is 1.9B or less. The upper and lower ends of the vertical stiffening member are not joined to the flange, and a predetermined gap is provided between the vertical stiffening member and the flange. The described steel beam. The steel frame beam according to any one of claims 1 to 4, wherein a lateral stiffening member extending in the axial direction of the beam is provided on the web at the beam end. A column-beam joint structure characterized in that the steel beam according to any one of claims 1 to 5 is joined to a column. The steel beam includes a beam joint portion joined to the column and a beam body portion joined to the beam joint portion via a splice plate.
The column beam according to claim 6, wherein the splice plate joints the web of the beam joint portion and the web of the beam main body to each other in a state of also serving as the vertical stiffening member. Joint structure. The steel beams are joined to the columns via splice plates and
The beam-column joining structure according to claim 6, wherein the splice plate is joined to each other the column and the web of the steel frame beam in a state of also serving as the vertical stiffening member.

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