JP2013079508A - Beam-column connection of rigid-frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a beam-column connection of a rigid-frame composed of a column of steel structure, steel framed reinforced concrete structure, or concrete filled steel tube structure and an H-shaped steel beam, which prevents early rupture of a weld zone from occurring at a beam end by flexural tensile stress, with easy construction and at favorable cost.SOLUTION: The upper and lower flanges 2a and 2b of a beam 2 formed of an H-shaped steel are weld connected to the side face part of the beam connection part of a column 1 formed of a square steel tube. The side face part of the flange 2a is provided with a hole 9 at the position about 50 to 90 mm away from the weld part 9 at the flange end of the beam 2 toward the beam center, with a predetermined depth in the direction perpendicular to the axis of the beam 2. Both of the side face parts of the upper and lower flanges are provided with one or plurality of holes 9. The hole 9 is formed with a hand drill or the like.

Description

  The present invention relates to a column-to-beam joint of a rigid frame constructed by welding a H-shaped steel beam to a steel, steel reinforced concrete, or concrete-filled steel tubular column, and welding the flange end of the beam by bending tensile stress. In addition to preventing early breakage of the portion, it is possible to provide a column beam joint portion of a rigid frame that is easy to construct and advantageous in cost.

  A building having a rigid frame structure is deformed as shown in FIGS. 8A and 8B by a horizontal load at the time of an earthquake, and accordingly, the beam and the column are deformed as shown in FIG. 8C. A large bending tensile stress and bending compressive stress are generated at the beam end.

  For this reason, in a beam-column joint that is widely applied as a beam-column joint of this type of building and is formed by welding a beam of an H-shaped steel to a column, for example, FIG. As shown in FIG. b), the stress is most concentrated on the groove shoulder 21a at the start end of the flange end welded portion 21 of the beam 20, and the flange of the beam 20 embrittled by welding, particularly under bending tensile stress. It has been pointed out that the end weld 21 may be prematurely destroyed by brittle fracture.

  Therefore, when welding an H-shaped steel beam to a steel frame as a column, the flange end of the beam to be welded is widened, and the beam end joint and the widened portion are yielded almost simultaneously to expand the plasticization area. By applying a structure that avoids brittle fracture near the joint, or a plasticized region that yields before the beam end at a position near the beam center from the flange end weld of the beam. By applying a beam structure such as a so-called dogbone type, an early breakage of the welded portion of the flange end of the beam is prevented.

  For example, in Patent Documents 1 and 2, as shown in FIGS. 10A and 10B, a rib plate 22 is attached to the side surface of the upper and lower flanges 20a of the beam 20 made of H-shaped steel, and the flange end of the beam 20 is attached. A structure for widening the portion is disclosed.

  Patent Document 3 discloses a so-called dogbone type beam as shown in FIG. That is, a method is described in which the plasticized region 23 is provided by reducing the flange width in a curved shape from the flange end welded portion 21 of the beam 20 made of H-shaped steel toward the center of the beam.

  Further, in Non-Patent Document 1, a plurality of through holes 20b are formed on the flange surface of the upper and lower flanges 20a closer to the center of the beam from the flange end welded portion 21 of the beam 20 made of H-shaped steel as shown in FIG. 11 (b). A method is described in which a plasticized region 23 is provided by opening.

JP 2004-44100 A JP 2000-96706 A Japanese Patent Laid-Open No. 2004-27840

Experimental study on deformation capacity of field-welded column beam welded joints using perforated flange method (The Architectural Institute of Japan, 585, p.155-p.161, November 2004)

  However, the method of welding the rib plate to the side of the flange of the beam requires welding so that the rib plate and the flange of the beam are completely integrated. When this occurs, there is a risk that early breakage may occur starting from this portion.

  In addition, the so-called dog bone type beam and the type of beam with a through hole in the flange surface are a method of positively plasticizing the position near the beam center from the weld end of the flange end of the beam by a cross-sectional defect. There is a problem that reduction in yield strength is inevitable.

  In addition, a method of manufacturing a welded assembly H-section steel by cutting the beam flange into a widened shape has also been implemented, but because the beam flange is cut into an integrated widened shape, the loss of steel during production increases. If a cut notch is generated at the end of the widened portion, there is a risk that early breakage may occur starting from this portion.

  The present invention has been made in order to solve the above-described problems, and can prevent an early breakage of a welded portion of a flange end of a beam due to bending tensile stress, and can be easily installed and cost-effective. The object of the present invention is to provide a column-to-column joint of a frame.

  The beam-to-column connection part of the frame of the present invention is a beam of a rigid frame constructed by welding the upper and lower flanges of a beam made of H-shaped steel to a column of steel, steel reinforced concrete, or concrete-filled steel pipe. In the joint portion, a hole is provided at a predetermined depth from a beam end weld portion of the flange to a side surface portion near the center in the beam longitudinal direction.

  The column beam joint of the present invention relieves stress concentrated on the flange end weld of the beam due to bending tensile stress caused by horizontal loads such as earthquakes in particular, and prevents early failure of the beam flange end weld. This is designed to prevent this.

  According to the beam-column joint of the present invention, the flange end weld of the beam is positively plasticized under bending tensile stress from the flange end weld of the beam to the flange side surface near the beam center. It is possible to relieve stress acting on the portion and prevent early breakage of the welded portion of the flange end of the beam.

  The hole should be formed in the flange width direction, and the size and diameter should be several millimeters to several tens of millimeters. The position of the hole depends on the beam size, but it is roughly from the flange end weld of the beam. If it is the range of about 50 mm-90 mm, there exists an effect which relieve | moderates the stress which acts on a flange end welding part, and is desirable.

  Furthermore, it is possible to relieve stress concentration at the flange end welds by simply providing holes on either side of the upper or lower flange of the beam. However, if holes are assumed to be deformed during an earthquake, they should be provided on both sides of the upper and lower flanges. A plurality of them may be formed. In addition, a hole can be easily opened using a hand drill etc. at the time of shipment from a factory or a construction site.

  According to another aspect of the present invention, there is provided an H-section steel in which a hole is provided in a flange side surface in the vicinity of a longitudinal end portion. The size and position of the holes are the same as described above.

  By using such an H-shaped steel as a beam for a rigid frame, the stress that acts on the flange end weld of the beam at the beam-column joint is reduced, especially by bending tensile stress associated with horizontal loads such as earthquakes. Thus, early breakage of the welded portion of the flange end of the beam can be prevented.

  The present invention relates to a beam-to-flange end welded portion in a beam-to-column joint formed by welding the upper and lower flanges of a beam made of H-shaped steel to a side surface of a steel frame such as an H-shaped steel or a square steel pipe as a column. By providing a hole in the side of the flange near the center of the beam, the stress acting on the flange end weld of the beam due to bending tensile stress accompanying horizontal load such as earthquake is alleviated, and the flange end weld of the beam Early breakage of the part can be prevented in advance.

  Moreover, since the hole can be easily formed by a hand drill or the like at the time of shipment from the factory or after carrying in the field, construction is easy and extremely advantageous in terms of cost.

The column beam junction part which shows one Embodiment of this invention is shown, (a) is the perspective view, (b) is the principal part enlarged view in figure (a), (c) is the side which shows the flange end welding part of a beam FIG. (A) is explanatory drawing for examining the effect by FEM analysis, (b) is a graph which shows the material characteristic of each member, (c), (d) is a side view of the flange end welding part of a beam, FIG. It is a graph which shows the influence of the hole position which gives to the distortion in a flange end welding part. It is a graph which shows the influence of the hole depth which gives to the distortion in a flange end welding part. It is a graph which shows the influence of the hole diameter which gives to the distortion in a flange end welding part. It is a graph which shows the influence of the number of holes which gives to the distortion in a flange end welding part. (A), (b), (c) is a graph which shows the strain distribution of the flange width direction in a flange end welding part. A building with a ramen structure is shown, (a) is a side view thereof, (b) is a side view showing a deformation state and moment distribution due to a horizontal load, (c) is a column beam joint showing a deformation state of a beam due to a horizontal load. It is a side view. The column beam connection part of a steel frame frame structure is shown, (a) is a top view, (b) is a side view of the flange end welding part of a beam. (A), (b) is a perspective view of the column beam junction which uses the beam which expanded the flange edge part. (A) is a plan view of a so-called dog-bone type beam, and (b) is a plan view of a beam-column joint using a beam of a type in which a hole is formed in the flange surface.

  FIG. 1 shows an embodiment of the present invention. In the figure, upper and lower flanges 2a and 2a of a beam 2 made of H-shaped steel are respectively connected to upper and lower horizontal diaphragms 3 and 3 at a beam joint portion of a column 1 made of a square steel pipe. The web 2b of the beam 2 is joined by a joining plate 4 and a plurality of joining bolts 5 via a bracket (not shown).

  The upper and lower horizontal diaphragms 3 and 3 are formed in a rectangular plate shape that is slightly larger than the outer diameter of the column 1, pass horizontally through positions corresponding to the upper and lower flanges 2 a and 2 a of the beam 2, and are integrally welded to the column 1. Has been. The end portions of the upper and lower flanges 2a, 2a of the beam 2 are joined to the edge portions of the upper and lower horizontal diaphragms 3, 3 by welding.

  The bracket is vertically installed on the side surface between the upper and lower horizontal diaphragms 3 and 3 of the column 1 and is integrally welded to the side surface of the column 1. And the edge part of the web 2b of the beam 2 is joined to the bracket by the joining plate 4, the joining plate 4, and a plurality of joining bolts 5 penetrating the bracket.

  Butt welding is used for welding between the upper and lower flanges 2a and 2a of the beam 2 and the upper and lower horizontal diaphragms 3 and 3, and the ends of the upper and lower flanges 2a and 2a of the beam 2 and the upper and lower horizontal diaphragms 3a and 3a are respectively in the same horizontal plane. A groove 6 and a backing metal 7 are provided at both abutting portions. The groove 6 is filled with weld metal.

  Further, one or a plurality of holes 8 are formed in both side surfaces of the upper and lower flanges 2a, 2a of the beam 2. The hole 8 is formed horizontally in the direction perpendicular to the axis of the beam 2 at a position closer to the center side of the beam 2 from the flange end weld 9 of the beam 2.

  The hole 8 may be provided only on one of the upper and lower flanges 2a and 2a or on one side surface of the upper and lower flange 2a.

  Reference numeral 10 denotes a horizontal stiffener that reinforces the web 2b of the beam 2 and is attached to the side surface of the web 2b near the flange end weld 9 of the beam 2 by welding as necessary.

  In such a configuration, as shown in FIGS. 8 (a) and 8 (b), when a building is deformed by a horizontal load during an earthquake, and columns and beams are deformed as shown in FIG. 8 (c). A large bending tensile stress and bending compressive stress are generated at the end of the beam, and the stress is concentrated at the welded portion of the upper and lower flange ends of the beam.

  However, since one or more holes are provided in the flange side near the beam center from the flange end welded part of the beam, this part is first plasticized to reduce the stress. It is possible to prevent the fracture fracture of the lower flange end weld.

  Next, the significance and effect of providing a hole in the flange side surface closer to the center of the beam than the flange end welded portion of the beam will be examined using FEM analysis examples (FIGS. 2 to 7, Tables 1 to 4). reference).

  Under the conditions shown in FIGS. 2 (a) to 2 (d), the position of the hole provided in the side surface of the flange of the beam, the depth of the hole, the diameter of the hole, and the number of holes are determined by the bending tensile stress. The effect of the flange end weld on the strain in the Z direction was examined.

  In FIG. 2 (a), symbols a, b, and c are respectively attached to the flange 2a, the diaphragm 3, and the flange end weld 9 of the beam 2 in the beam-column joint shown in FIGS. 1 and 2 (c). Correspond.

  2 (b) shows the material properties of the diaphragm, weld metal, and beam flange, and FIGS. 2 (c) and 2 (d) show a side view and a partial plan view of the flange end weld of the beam, respectively. FIG.

  As shown in the figure, the position of the hole is represented by a distance d (mm) from the flange end welded portion 9 (more specifically, the groove shoulder) of the beam 2, and the depth of the hole is x (mm), The diameter of is represented by Φ (mm).

  3 and Table 1 show the effect of the hole position (d) on the Z-direction strain of the flange end weld, and the hole position (d) is within the range of 50 mm <d <90 mm. It was confirmed that the effect of halving the strain in the Z-direction of the flange end welded portion can be expected as compared with a structure in which a hole is not provided in the side surface portion of the flange (hereinafter referred to as “conventional type”).

  4 and Table 2 show the influence of the hole depth (x) on the strain in the Z direction of the flange end weld. When the hole diameter Φ = 10 mm, the hole depth (x) = 20. It was confirmed that the maximum effect was obtained at ˜30 mm.

  FIG. 5 and Table 3 show the effect of the hole diameter (Φ) on the strain in the Z direction of the flange end weld. By increasing the hole diameter (Φ), the strain concentration in the flange end weld is increased. Can be relaxed. However, if the hole diameter (Φ) is too large (for example, Φ ≧ 15 mm), the plastic deformation of the hole portion becomes large, and a relatively early reduction in rigidity was confirmed. In this analysis result, it is considered that Φ ≦ 10 mm is appropriate.

  6 and Table 4 show the influence of the number of holes on the Z-direction strain of the flange end weld, and it was confirmed that the effect can be expected by increasing the number of holes.

  Based on the results of this analysis, the beam-to-column joint with a fracture-preventing hole in the beam flange can be expected to be effective by appropriately designing the position of the hole, the depth of the hole, the diameter of the hole, and the number of holes. Compared with the maximum strain value of the flange end weld of the beam generated at the beam-column joint of the mold, it was confirmed that the strain value could be reduced to less than half.

  7 (a), (b), and (c), especially the cross section of the beam (flange width (B (mm)), flange plate thickness (tf (mm)), and diaphragm plate thickness (td (mm))) Thus, the influence of the hole on the strain in the Z direction of the flange end weld is shown.

  As is clear from each figure, it was confirmed that the strain value of the flange end weld can be reduced by providing a hole in the side surface of the flange regardless of the cross-sectional shape of the beam.

  From the above analysis results, the hole position is within the range of tf ≦ d ≦ 13tf / 5, the hole depth is B / 20 ≦ x ≦ 2B / 15, and the hole diameter is tf / 5 ≦ Φ ≦ 3tf / 5. If it exists, it is thought that the concentration of distortion on the flange end welded portion of the beam can be alleviated regardless of the cross-sectional shape of the beam.

  INDUSTRIAL APPLICABILITY The present invention can prevent early breakage of a flange end welded portion of a beam due to bending tensile stress, and can provide a steel-framed ramen-framed column-beam joint that is easy to construct and advantageous in cost.

DESCRIPTION OF SYMBOLS 1 Column 2 Beam 2a Beam flange 2b Beam web 3a Diaphragm 4 Joint plate 5 Joint bolt 6 Groove 7 Backing metal 8 Hole 9 Beam flange end weld 10 Horizontal stiffener

Claims (4)

  In a column-to-beam joint of a rigid frame constructed by welding an H-shaped steel beam to a steel-frame, steel-framed reinforced concrete or concrete-filled steel tubular column, the flange end weld of the beam is closer to the center of the beam. A column beam joint of a ramen frame, wherein a hole is provided in a side surface of the flange.   2. The beam-to-column joint of a rigid frame according to claim 1, wherein one or a plurality of the holes are provided on both side surfaces of the upper and lower flanges.   The column-to-beam connection part of the rigid frame according to claim 1 or 2, wherein the hole is provided on a flange side surface near the center of the beam 50 to 90 mm from the flange end welding part of the beam. Beam joint.   An H-section steel, wherein a hole is provided in a flange side surface near the longitudinal end.

Images