JPH0687071A - Welding method for steel beam and steel column - Google Patents

Abstract

PURPOSE:To provide a column-beam joining structure having an enough resistance without a cross section flaw by downward welding a flange on the lower side of a beam in a building site without providing a scallop. CONSTITUTION:In a welding method by which a lower flange 11 of an H-shaped beam 1 having an upper and lower flanges in the horizontal direction on its top and bottom is joined with a steel column 2 by downward welding, a notched part 12b is provided on the tip end lower part of a web 12 of the beam, an opening part combined with the notched part and the sectional face of a groove 11a at the end part of the flange under the notched part is clogged with a thin steel clogging plate 17 having the same shape to the opening part and the inside of the groove 11a is welded by welding toward both ends having the clogging plate 17 as a turning back point of a welding bead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of welding a steel frame beam to a steel frame column in a steel frame structure composed of a steel frame column and a steel frame beam.

[0002]

2. Description of the Related Art As a method of joining a steel beam to a steel column in a steel structure composed of a steel column and a steel beam, a part of the beam material is welded to the column material in a factory in advance, In the field, there is a joining method of bolting beam members together. Although this method has the advantage that welding work is not required at the construction site, especially at high places, it also has the disadvantage of increasing the number of joints, and at the construction site, the welding method of directly welding the beam to the steel column is often adopted. Has been done. In either case, welding of the steel beam to the steel column is generally performed by welding, and the welding method is generally fillet welding from one side of the flange by the groove. FIG. 4 shows an example of a conventional joint structure in which a beam member is directly welded to a steel column. 1 is a beam member made of H-shaped steel, 2 is a column member made of square steel pipe columns, 11 is a lower flange of the beam member, 11 'is an upper flange, 12 is a web, 13 and 13' are provided at both ends of the web portion. It is a quarter-arc cutout called a scallop. In this example, both the upper and lower flanges are single-sided welds from above by inserting backing metal 14, 14 'on the back surface of the flange, and 15 and 15' are weld metals.

Since the welding lines of the upper and lower flanges are continuous over the entire width of the flange, the scallop 13 'at the lower part of the upper flange 11' interferes with the insertion of the backing metal 14 'corresponding to the welding length. The scallop 13 on the upper part of the lower flange 11 is a cutout of the web that interferes with welding the web position at the center of the flange.

When welding is performed in advance at the factory, the lower flange can be reversed and the construction can be performed in the same manner as the upper flange. Therefore, the welding surface is the outer side of both the upper and lower flanges, and the purpose of scalloping is the backing metal. Limited to inserting. Therefore, although the shape of the scallop may be matched with the cross section of the backing plate, it is usually arcuate for reasons such as ease of processing and being less likely to cause hair cracks. There are no specific standards for the size of the scallop, but the Architectural Institute recommends a radius of 35 mm or more.

However, such a scallop not only requires labor for working, but also has a large cross-section defect, which significantly reduces the proof stress of the joint with the column against repeated loads such as earthquakes, leading to early fracture. Needless to say, it is not preferable in terms of structure because it causes the generation. Therefore, a cast steel hardware functioning as a backing metal that sandwiches the web portion without a scallop has been developed. Japanese Utility Model Publication No. 59-42237 and Japanese Patent Application Laid-Open No. 63-177971.
It is disclosed in the publication.

The backing metal described in Japanese Utility Model Publication No. 59-42237 will be described with reference to FIGS. FIG. 5 is a perspective view of this backing metal, and FIG. 5 (b) is its AA cross section. FIG. 6 is a perspective view of an H-shaped steel groove portion into which the backing plate is fitted. Figure 6
The groove surface 11a of the groove is continuous to the left and right with the web 12 at the end of the flange 11, and the backing metal 51 is provided with a slit 52 in the center for straddling the web 12 so as to fit into this. Since the transition portion 12a (fillet portion) between the flange 11 and the web 12 of the H-section steel is rounded,
Both sides of the slit 52 of the backing metal 51 are curved surfaces corresponding to this R
It is 52a. Further, since the groove angle 11 is formed on the groove surface 11a of the H-shaped steel, the same angle is formed on the back wall portion 52b of the slit 52 of the backing plate 51 as shown in FIG. 5 (b). Is attached. FIG. 7 is a perspective view of the H-shaped steel of FIG. 6 with the backing plate 51 of FIG. 5 attached, and shows that the above-described configuration forms a continuous groove groove across the web. .

Further, the backing metal disclosed in Japanese Patent Laid-Open No. 63-177971 can be used only for rolled H-section steel, whereas the backing metal is welded with variations in the shape and size of the fillet portion. The shape and dimensions of the slit are improved so that they can be applied to H-section steel.

[0008]

As is clear from the above description, since the backing plate 51 can be used only for welding from the outside of the flange, it is applicable to the downward welding of the lower surface flange at the construction site. The problem of not being able to do it and wanting to eliminate scallops has not been solved. The present invention, particularly by adopting a novel method for welding the lower flange side,
The purpose is to eliminate scallops completely and realize a column-beam joint structure with sufficient proof strength.

[0009]

The welding method of the present invention is a welding method for joining a lower flange of a steel frame beam made of a shaped steel having horizontal flanges to a steel column by downward welding. A notch is provided in the lower part of the front end of the web, and the opening part is closed by a cover plate made of a thin steel plate having the same shape as the opening part combining the notch and the groove cross section of the flange end part under the web part. A method of welding a steel beam to a steel column, comprising welding the inside of the groove of the flange toward both ends by using a plate as a turning point of a welding bead.

[0010]

[Operation] According to the present invention, in the downward welding to the lower flange, a notch is provided at the lower end of the web, and a thin steel plate having the same shape as the opening part formed by combining the notch and the groove cross section under the notch is used. The opening is closed by a blocking plate that is formed, and the welding is performed in the groove toward the flange end by using this blocking plate as the turning point of the welding bead.
The blocking plate is completely melted into the weld metal, the notch of the web is completely filled with the weld metal, and no defect is left, so that a column-beam joint structure having sufficient proof strength is realized.

[0011]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a side view of this joint structure, in which 1 is a beam member, 2 is a column member, and other parts common to those in FIG. The upper and lower flanges are shown before welding. The beam is 500 mm x 300 mm H-section steel, the flange thickness is 19 mm, and the web 12 is 12 mm thick.

In this embodiment, the web on the lower surface of the upper flange is provided with a rectangular notch which can be penetrated by the backing metal 14 'in place of the scallop, and the periphery of the web is welded after welding. A backing metal as shown in FIG. 5 cited as a technique may be used. A notch 12b with a height of 22 mm from the bottom surface of the flange is provided at the top of the lower flange, and a 6 mm thick steel plate cover with the same shape as the groove section of the flange end at the bottom. A plate 17 is applied to block this opening.

FIG. 2 is a perspective view of the joint structure in this embodiment as seen from the side of the column with the column removed. A groove 11a is formed at the end of the flange 11 of the beam 1. The tip of the web 12 extends to the position where it hits the pillar, but the notch 12b is processed in the lower part of the tip, that is, the upper part of the groove as described above, and the opening part that matches the groove cross section of the lower part is as described above. It is blocked by the cover plate 17. The blocking plate 17 is fixed to the center position of the plate thickness of the web 12 by spot welding or the like.
14 is a backing metal.

FIG. 3 is a side view showing the construction procedure of this embodiment as seen from the side of the pillar. First, in (a), the blocking plate 17 is placed in the center of the web 12, welding is started from the flange end, and the blocking plate is used as a turning point of the welding bead to weld the inside of the groove on the right side to the outside with the torch 3. The state is shown. The welding method is gas shielded arc welding such as carbon dioxide welding. The notch 12b of the above-mentioned web is lifted up by the weld metal to weld this portion. When the welding on one side is completed as shown in (b), the covering plate 17 portion is also folded at the welding bead turning point as shown in (c). As the other side min 15c
Welding. When welding the connection with the cover plate 17, if the molten pool is well boiled and the air bubbles escape so that the arc is folded back without cutting the arc, the cover plate completely melts into the weld metal by welding from both sides, and No defects such as pinholes and slag entrapment occur.
Therefore, if the plate thickness of the blocking plate 17 is too thick, unmelted portion will be left, and if it is too thin, it will be broken during welding and lose the damming function. According to experiments, welding conditions were
If V and 300 A, the thickness of the cover plate 17 is 3 to 6 m.
The range of m is good. As a welding method used in the present invention, gas shielded arc welding that does not break the arc is preferable.
Since the other parts are merely normal downward welding, there is no problem and the joining is completed.

[0015]

According to the present invention, it is possible to realize a column-beam joint structure having sufficient proof stress without cross-section loss even in the case of joining at the construction site where the upper and lower flanges are welded downward. , Produces excellent effects.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a first embodiment of the present invention.

FIG. 3 is a side view showing a construction procedure in the first embodiment of the present invention.

FIG. 4 is a side view showing a conventional technique.

FIG. 5 is a perspective view showing a conventional technique and a partial sectional view thereof.

FIG. 6 is a perspective view showing a conventional technique.

FIG. 7 is a perspective view showing a conventional technique.

[Explanation of symbols]

 1 Beam material 11 Flange 11a Groove 12 Web 12b Notch 13 Scallop 14 Backing metal 15 Weld metal 17 Cover plate 2 Column material 3 Welding torch

Claims (1)

[Claims] 1. A welding method for joining a lower flange of a steel beam made of shaped steel having horizontal flanges to a steel column by downward welding, wherein a notch is provided at a lower end of a web of the steel beam. The opening is closed by a blocking plate made of a thin steel plate with the same shape as the opening that matches the groove cross section of the flange end at the bottom of the notch, and the opening is closed at both ends as the turning points of the welding bead. A method for welding a steel frame beam to a steel frame column, which comprises welding the inside of the groove of the flange toward the side.