JPH1161992A - Column-beam joint of steel frame structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it hard to crack in a column-beam joint even in an earthquake, by forming the flange at the end of the beam of the column-beam joint, with a different kind of steel member having a lower yielding point and tensile strength and a higher toughness and ductility than a diaphragm and tapering the beam end flange toward the beam direction. SOLUTION: A beam end flange 3 welded on a continuous diaphragm 2 fitted to a square steel pipe column 1 is formed of a different kind of steel member having a lower yielding point and tensile strength and a higher toughness and ductility than a diaphragm 2. And cracks are not easily brought in the diaphragm 2 and the column 1 of which repair is difficult, by using a different kind of steel member in the beam end flange 3, and the beam end flange having a lower strength becomes more easily breakable. And the beam end flange 3 a little separated from the connected part of the beam of which repair is difficult, is broken by forming a tapered part toward the beam direction. And hence, cracks do not easily arise in the column-beam joint even in an earthquake.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a column-beam joint of a steel frame.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a beam end flange 3 welded to a through-diaphragm 2 attached to a rectangular steel tubular column 1 is formed of the same steel type as the diaphragm 2, and the beam end flange 3 is formed. The beam 4 has a uniform cross section centered on the web 4, and a beam center flange 5 is attached to the beam end flange 3 via a splice plate 6 and a backing metal 7. For this reason, it is easy for a crack to propagate from the vicinity of the welded portion of the beam-end flange of the column-beam joint, which is in the most severe stress state in the frame during a large earthquake. FIG. 4 shows an example of a schematic diagram of damage caused from a beam end. In the same figure, 8 is a weld metal, 9 is a crack in the base material at the bottom of the scallop, 10 is a crack in the heat-affected zone on the flange side, 11 is a crack in the heat-affected zone on the diaphragm side, and 12 is a crack in the base material of the diaphragm. In the example of cracks and fractures shown in Fig. 4, the cracks generated from the beam ends are very close to the complex column-beam joints compared to other parts, making it difficult to repair and reinforce after the earthquake. There is a point.

[0003]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to make it difficult for a column-beam joint which is in the most severely stressed state in a frame during a large earthquake to crack.

[0004]

The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to the embodiment. The present invention provides a diaphragm 2 of a square steel tubular column 1 with: At the column-beam joint of the steel frame to which the beam end flange 3 is welded, the beam end flange 3 is formed of a dissimilar steel material having a lower yield point and tensile strength than the diaphragm 2 and having high toughness and ductility. The beam end flange 3 or the diaphragm 2 is provided with a tapered portion 13 directed in the beam direction.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. 1. Reference numeral 1 denotes a rectangular steel pipe column, and a beam end flange welded to a through-diaphragm 2 attached to the rectangular steel pipe column 1. 3 is made of a dissimilar steel material having a lower yield point and a lower tensile strength than the diaphragm 2 and a high toughness and ductility, and a tapered portion 13 is provided on the beam end flange 3 in the beam direction.

FIG. 2 shows a second embodiment of the present invention, in which a beam end flange 3 to be welded to a diaphragm 2 is formed of a dissimilar metal having a lower yield point and lower tensile strength than a diaphragm and having higher toughness and ductility. The diaphragm 2 is provided with a tapered portion 13 directed in the beam direction.

[0007]

As described above, according to the present invention, the use of a dissimilar steel material having a lower yield point and a lower tensile strength than the diaphragm at the beam end flange makes it possible to crack the diaphragm and the column which are difficult to repair and reinforce. It is difficult to repair and reinforce the beam because the beam end flange or the diaphragm has a tapered part in the beam direction at the beam end flange or diaphragm. The flange at the end of the beam slightly away from the beam joint eventually breaks,
Reinforcement can be performed relatively easily as compared with the conventional construction method. In addition, since a highly ductile material is used for the beam end flange, there is an effect that the seismic energy absorption capacity at the beam end is sufficiently ensured.

[Brief description of the drawings]

1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a side view.

FIGS. 2A and 2B show a second embodiment of the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a side view.

3A and 3B show a conventional example, in which FIG. 3A is a plan view and FIG. 3B is a side view.

FIG. 4 is a schematic view of damage caused from a beam end flange.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rectangular steel pipe column 2 Diaphragm 3 Beam end flange 13 Tapered part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kiyoshi Tanaka 4-6-15 Sendagaya, Shibuya-ku, Tokyo Inside Fujita Co., Ltd.

Claims (1)

[Claims] 1. A column / beam joint of a steel frame for welding a beam end flange to a diaphragm of a square steel tubular column,
The beam end flange is formed of a dissimilar steel material having a lower yield point and a lower tensile strength than the diaphragm and having high toughness and ductility, and the beam end flange or the diaphragm is provided with a tapered portion directed in the beam direction. Column and beam joints of steel structure.