JP4655492B2 - Manufacturing method for beam-column joints - Google Patents

Description

  The present invention relates to a method for manufacturing a beam-column joint in a steel structure, and particularly relates to a method for manufacturing a beam-column joint having a closed cross-section column and an H-shaped steel beam, which is excellent in earthquake resistance.

  It is said that the beam-column joint by welding in the steel structure has the highest probability of being destroyed in the event of an earthquake or the like due to material deterioration of the weld or welding defects. In the case of the inner diaphragm type column, if a defect occurs in the electroslag welded portion where the diaphragm is welded to the column skin plate, the stress from the beam causes a large opening and deteriorates the earthquake resistance.

  FIGS. 5A and 5B are diagrams for explaining the inner diaphragm type joint structure 100 in which the column is a closed section and the beam is an H-shaped steel. FIG. 5A is a partial sectional view, FIG. Inside, a diaphragm 400 is attached by electroslag welding at a position facing the beam flange 310 of the beam 300.

  If the reinforcing material is not provided at a position facing the beam web 320 inside the column 200, out-of-plane deformation occurs in the column skin plate 210. A bending moment having an axial stress 800a of the beam flange 310, a part of the axial stress 800 of the beam web 320, and a shearing force 700 of the beam web as an acting stress is applied to the diaphragm 400 via the electroslag weld A. Works. Stress flows from the beam flange 310 to the diaphragm 400 as indicated by an arrow 900.

  FIG. 6 is a view showing a configuration of an electroslag welded portion A for welding the column skin plate 210 and the diaphragm 400. The welded metal 600 is welded to the groove portion of the diaphragm 400 and the backing metal 500 disposed on both sides thereof. And

  Electroslag welding of the beam-column joint is a large heat input welding with a heat input of 400 kJ / cm or more. Therefore, a gap 10a may be generated between the backing metal 500 and the column skin plate, and the beam web is formed in the gap 10a. When a bending moment having an axial stress 800 of 320 or the like acts as a working stress, the air gap 10a is opened to cause a crack, and the column beam joint is destroyed.

Patent Literature 1 and Patent Literature 2 relate to an electroslag welding method for preventing such destruction, and describe that a backing metal and a column skin plate are welded to prevent generation of voids therebetween.
JP-A-8-155661 Japanese Patent Laid-Open No. 2002-54233

  However, the methods described in Patent Document 1 and Patent Document 2 are not preferable because the amount of welding work in a narrow column increases and the number of welds increases. Furthermore, even if the backing metal and the column skin plate are welded, there is a concern that fatigue cracks are introduced by long-term use, opening due to a bending moment from the beam, and breaking the column beam joint.

  Therefore, the present invention acts on the electroslag welded portion, reduces the bending moment itself that opens the backing metal in the welded portion and the column skin plate, and suppresses the destruction of the column beam joint. An object is to provide a manufacturing method.

  The present inventors diligently studied the bending moment acting on the electroslag weld, and obtained the following knowledge. 1 When the column has a box-shaped cross section and the inner web is not installed inside the column skin plate to which the beam web is attached, the axial stress of the beam web is transmitted to the column web and diaphragm by the out-of-plane bending resistance of the column flange. The

Therefore, in addition to transmitting the axial force of the beam flange to the diaphragm, it is necessary to determine the diaphragm plate thickness and the mounting position on the column skin plate from the balance of the forces considering the axial stress of the beam web. The bending stress acting on the diaphragm is defined as the axial stress of the beam flange, the axial stress of the beam web, and the shearing force of the beam web.
3. The axial stress of the beam web causes out-of-plane deformation of the column skin plate, and as a result, acts as an axial force and bending moment of the diaphragm, resulting in a gap between the diaphragm and the backing metal in the electroslag weld. Then, the gap is opened, and the earthquake resistance of the column beam joint is deteriorated by the generation of cracks.

The present invention has been made by further study based on the above knowledge. That is, the present invention is a manufacturing method of a column beam joint that joins an inner diaphragm type column having a closed cross-section structure and an H-shaped steel beam. A method of attaching the inner diaphragm of the column and the flange of the beam to the column skin plate, wherein an interval between the upper and lower diaphragms is smaller than an interval between the upper and lower flanges of the beam and the diaphragm of the column from the beam A method of manufacturing a beam-column joint characterized in that the beam is eccentrically attached by a predetermined distance so as to minimize the bending moment acting on the beam.

  2. The method of manufacturing a beam-column joint according to 1, wherein the bending moment is obtained as an axial stress of a beam flange, an axial stress of a beam web, and a shearing force of the beam web.

  According to the present invention, even if a gap is generated in the electroslag welded portion, the distance between the upper and lower diaphragms is narrower than the distance between the upper and lower beam flanges. Column beam with excellent seismic resistance by reducing the effect of bending moment, which is caused by directional stress, axial stress of the beam web, and shearing force of the beam web, on the electroslag welds, suppressing the occurrence of cracks from the air gap A joint is obtained.

The inner diaphragm type and the through diaphragm type are generally used for the beam-column joint, but the basic stress transmission method from the beam to the column in both types is the same, so the inner diaphragm type column beam The present invention will be described using the joint. In the present invention, the plate thickness of the diaphragm is equal to or greater than the plate thickness of the beam flange.
FIG. 1 is a diagram for explaining the present invention, in which (a) is a partial sectional view of a beam-column joint to which the present invention is applied, and (b), (c) are columns in the beam-column joint shown in (a). An enlarged detail view of the part where the diaphragm and beam flange are attached to the skin plate is shown. In (b) and (c), the electroslag welded portion is omitted.

  In the figure, 1 is a column beam joint, 2 is an inner diaphragm column, 21 is a column skin plate to which the beam 3 is attached, 3 is a beam, 31 is an upper flange of the beam, 31a is a lower flange of the beam, and 32 is a beam. The web 4 is an upper diaphragm attached to the column skin plate 21 at a position substantially opposite to the beam flange 31. 4a is a lower diaphragm attached to the column skin plate 21 at a position substantially opposite to the beam flange 31a.

  In the manufacturing method according to the present invention, first, the distance between the upper and lower diaphragms 4 and 4a is made narrower than the distance between the upper and lower beam flanges 31 and 31a, thereby increasing the rigidity of the column skin plate 21 and suppressing out-of-plane deformation. Furthermore, the position where the diaphragm 4 is attached to the column skin plate 21 is defined in relation to the beam flange so that the bending moment acting on the diaphragms 4 and 4a is minimized.

  When the center line a of the beam flange 31 (31a) and the center line b of the diaphragm 4 (4a) are decentered, the axial stress of the beam flange, the axial stress of the beam web, and the beam web acting on the diaphragm 4 (4a) Since the bending moment using the shearing force as the acting stress changes, the center line a of the beam flange 31 (31a) and the center line b of the diaphragm 4 (4a) are decentered by the distance obtained so that the bending moment is minimized. The diaphragm 4 is attached to the pillar skin plate.

  At this time, the upper diaphragm 4 is decentered in the-direction with respect to the beam flange 31 (FIG. 1B), and the lower diaphragm 4a is decentered in the + direction with respect to the beam flange 31a (FIG. 1C). .

  FIG. 4 is a diagram showing the result of obtaining the influence of the eccentric distance e on the bending moment acting on the diaphragm by giving a forced displacement to the model specimen of the beam-column joint of the rigid frame structure by the finite element method. 2 shows test conditions, and FIG. 3 shows a test specimen.

  The model specimen was a ½ symmetric model, and a forced displacement was given to the beam end portion with the column end support condition being a pin joint. As is apparent from FIG. 4, when the eccentric distance e is −1.4 mm, the bending moment is 0. Therefore, the eccentric distance e in FIGS. 1B and 1C is set to 1.4 mm.

  In the above description, the eccentric distance was obtained by the analysis by the finite element method using the model specimen, but the method for obtaining the eccentric distance in the present invention is not limited, and the eccentric distance is a loading test of the entity model. You may ask for it.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram explaining the column beam junction part which concerns on one Embodiment of this invention, (a) is a fragmentary sectional view, (b) is a figure explaining the attachment position of the upper diaphragm and the upper flange of a beam, (c) is lower The figure explaining the attachment position of the lower flange of a diaphragm and a beam. The schematic diagram explaining the test conditions of an Example. The schematic diagram explaining the test body of an Example. Example. It is a figure which shows the column beam junction part of a prior art example, (a) is a fragmentary sectional view, (b) shows a top view. The enlarged view of the electroslag welding part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Column beam junction 2 Inner diaphragm type column 21 Column skin plate 3 Beam 31 Beam upper flange 31a Beam lower flange 32 Beam web
4 Upper diaphragm 4a Lower diaphragm 10a Gap 100 Inner diaphragm type joint structure 200 Column 210 Column skin plate 300 Beam 310 Beam flange 320 Beam web 400 Diaphragm 500 Back metal 600 Weld metal 700 Beam web shear force 800 Beam web axis Directional stress 800a Axial stress 900 of beam flange Flow stress

Claims (2)

A method of manufacturing a column beam joint for joining a column of an inner diaphragm type having a closed cross-sectional structure and a beam of an H-shaped steel, and mounting the inner diaphragm of the column and the flange of the beam to the column skin plate The column is characterized in that the interval between the diaphragms is narrower than the interval between the upper and lower flanges of the beam, and the column is mounted eccentrically by a predetermined distance so that the bending moment acting on the column diaphragm from the beam is minimized. Manufacturing method for beam joints. 2. The method of manufacturing a column beam joint according to claim 1, wherein the bending moment is obtained as an axial stress of the beam flange, an axial stress of the beam web, and a shearing force of the beam web.

Images