JP3831332B2 - Beam-to-column connection structure of welded assembly box-shaped column with built-in diaphragm and H-shaped beam - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a construction steel beam-to-column connection structure of a welded assembled box-shaped column with a diaphragm and an H-shaped beam, and a welded assembled box-shaped column with a diaphragm and filled with concrete, and an H-shaped beam. It relates to the column beam connection structure.
[0002]
[Prior art]
Brittle fracture, which is a problem in the beam-column joint structure, occurs when three conditions of (1) increase in tensile stress load, (2) presence of notches, and (3) decrease in material toughness overlap. Therefore, by relaxing any one of the three conditions, brittle fracture from the part can be prevented.
As the prior art, there is a technique for preventing brittle fracture by relaxing the condition (3) of reducing the material toughness. The prior art is shown in FIG. 4. When a diaphragm is welded into a column having a box-shaped cross section, welding by electroslag welding is efficient because electroslag welding is a large heat input, but near the weld. However, in the prior art shown in FIG. 4, in order to solve this problem, a box-shaped cross-section column is attached to a beam attached to the welded heat-affected zone (HAZ portion). The beam is cut at the center of the beam and the diaphragm is welded into the cut box section column by carbon dioxide arc welding with low heat input, and then the cut box section column is re-welded, and then the box section column is welded. By welding the bracket to the outer periphery of the steel sheet, a decrease in fracture toughness of the weld heat affected zone is suppressed.
In addition, in electroslag welding, a special groove treatment and tack welding are performed, and the weld toughness is forcibly cooled during main welding to suppress a decrease in fracture toughness of the weld heat affected zone. Yes.
[0003]
[Patent Document 1]
JP-A-5-277725 [0004]
[Problems to be solved by the invention]
However, carbon dioxide arc welding is a multi-pass multi-pass welding, so it takes a lot of production time, and there is a problem that the cost increases because cutting and rejoining of box-shaped cross section columns are added in the production process. Furthermore, since it is necessary to perform multi-pass welding in a narrow part, welding defects are likely to occur, and there is a problem from the viewpoint of ensuring quality.
Further, in another conventional technique, there is a problem that a significant increase in cost is inevitable because work such as special groove processing and forced cooling occurs.
[0005]
The present invention is to provide an architectural steel column beam connection structure of a welded assembled box section column and an H section beam having an inner diaphragm which is economical and has excellent seismic performance, which solves the problems of the prior art. Objective.
[0006]
[Means for solving problems]
In order to solve the above-mentioned problems, the first invention of the present invention is a welded assembly box shape in which a beam-beam joint structure of a welded assembly box-shaped cross section column and a H-shaped cross section beam or a diaphragm is built in and a concrete is filled. In the beam-to-column connection structure of the cross-section column and the H-shaped cross-section beam, in the beam width direction, on the diaphragm inside the column, on the material axis of the beam and at a portion that is 1/10 or more of the column diameter away from the column cross section A hole having a length of at least twice the thickness of the beam web is provided.
[0007]
The second aspect of the present invention is a welded assembly box-shaped cross-section column or a welded-box-shaped cross-section column having a diaphragm built-in the diaphragm of the first aspect and an H-shaped cross-section column, or a weld-assembled box-shaped cross-section column filled with concrete. In the column beam connection structure with the H-shaped cross section beam, the shape of the hole is circular.
[0008]
[Action]
The present invention prevents brittle fracture by relaxing the condition of (1) an increase in the load of tensile stress in the brittle fracture condition. Tensile stress acts on the beam flange (upper or lower) due to the horizontal force at the time of the earthquake, and the stress is transmitted through the diaphragm at the beam-column joint. Furthermore, tensile stress acts on the slit tip due to out-of-plane deformation of the column skin plate caused by the plasticization of the beam flange. As a result, the slit tip opening displacement of the slit tip is changed. ) Becomes larger.
In the present invention, the length in the beam width direction is at least twice as long as the beam web thickness on the diaphragm inside the column, on the beam axis, and at a portion separated from the column cross-sectional center to the beam side by 1/10 or more of the column diameter. By providing the holes as described above, the tensile force acting on the slit tip is reduced, and as a result, the CTOD generated at the tip of the slit formed by the backing metal and the column skin plate is reduced, and the brittleness from the part is reduced. Suppress destruction.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A numerical experiment was conducted on the opening behavior of the slit tip due to the horizontal force at the time of an earthquake at the beam-to-column joint between the inner diaphragm type welded box-shaped column and the H-shaped beam.
The numerical experiment is nonlinear finite element analysis, and the object is a toroidal partial frame using a box-shaped cross-section column and an H-shaped cross-section beam that are electroslag welded to a column skin plate and an inner diaphragm. The load condition was that the upper and lower columns were pin-supported and a forced displacement was given to the beam. The member cross-sectional dimensions and material strength were set so that the beam yielded first.
As a result, within the range in which the framework shows elastic behavior, the CTOD generated at the slit tip formed by the metal plate of the electroslag welded part and the column skin plate is relatively small in the entire slit line. It has been found that the CTOD increases significantly at a position facing the beam web inside the panel. It was also found that this was caused by out-of-plane deformation of the column due to the increase in the bending moment share of the beam web due to the plasticization of the beam flange. This is because the stress transmitted from the beam web to the column causes the column skin plate to be deformed out of plane, separating the metal plate inside the joint panel and the slit formed by the column skin plate, that is, increasing the CTOD. Means that.
Based on the results of this numerical experiment, the present invention provides a diaphragm installed in a box-shaped cross-section column on the beam axis and on a portion separated by 1/10 or more of the column diameter from the column cross-section center to the beam side. A configuration is adopted in which a hole having a length in the width direction of at least twice the beam web thickness is provided.
[0010]
An embodiment of the present invention will be described with reference to FIGS. The welded box-shaped cross-section column 1 is formed by assembling four steel plates 2 into a box shape and welding them by carbon dioxide arc welding or submerged arc welding. An H-shaped cross-section beam 3 composed of upper and lower flanges 4 and 5 and a web 6 is welded to the welded assembly box-shaped cross-section column 1 by carbon dioxide arc welding or submerged arc welding. Prior to joining the H-shaped cross-section beam 3, the upper and lower diaphragms 7, 8 are applied to the positions corresponding to the joint portions of the upper and lower flange portions 4, 5 of the H-shaped cross-section beam 3 inside the welding assembly box-shaped cross-section column 1. Gold 9 is applied and welded by electroslag welding. The upper and lower diaphragms 7 and 8 have holes with a length in the beam width direction of at least twice the beam web thickness on the beam axis and at a distance of 1/10 or more of the column diameter from the column section center to the beam side. 10 is formed. The shape of the hole 10 may be any shape such as an oval, an ellipse, or a circle, but a circular hole is desirable in consideration of the ease of forming the hole. Moreover, the welded assembly box-shaped cross-section column may be filled with concrete as necessary in terms of the rigidity and proof stress of the member.
[0011]
2 and 3 show a beam-to-beam connection structure of a welded assembled box-shaped column with a built-in diaphragm of the present invention and an H-shaped beam, a conventional beam-to-column connection structure (upper and lower diaphragms on the beam axis and A horizontal load similar to that in an earthquake is not formed in the part that is 1/10 or more of the column diameter away from the center of the column cross-section and the beam width is at least twice the beam web thickness. The result of having carried out the numerical experiment which added is shown. The vertical axis in FIG. 2 is the shearing force acting on the beam, and the horizontal axis is the entire frame rotation angle. Also, the vertical axis in FIG. 3 is the CTOD generated at the slit tip formed by the metal plate of the electroslag welded portion and the column skin plate existing at the position facing the beam web inside the joint panel, and the horizontal axis is Shearing force acting on the beam.
As shown in FIG. 2, the beam-column joint structure of the present invention and the conventional beam-column joint structure also show substantially the same properties as the behavior of the entire frame.
However, in view of the relationship between CTOD and beam end load shown in FIG. 3, when both are compared with the same beam end load, the CTOD in the present invention is significantly reduced compared to the conventional one.
From this, by adopting the configuration of the present invention, it is not necessary to employ complicated welding conditions in order to increase the fracture toughness of the material (welded part), and high seismic performance can be ensured at low cost.
[0012]
【The invention's effect】
With the configuration of the present invention, even if highly efficient electroslag welding is adopted, the beam width is reduced to the beam side of the diaphragm inside the column and from the center of the column cross section to the beam side more than 1/10 of the column diameter. By providing a hole whose length in the direction is at least twice the beam web thickness, the tensile force acting on the slit tip at the time of an earthquake is reduced. As a result, the slit formed by the metal plate and the column skin plate CTOD generated at the tip can be reduced, and brittle fracture from the site can be suppressed.
[Brief description of the drawings]
1A and 1B are a plan view and a front view illustrating an embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship between beam end load and frame rotation angle according to an embodiment of the present invention. The figure which shows the relationship of CTOD-beam end load of one Embodiment of this invention FIG. 4 The figure which shows a prior art example
1: Welded assembly box-shaped column 2: Steel plate 3: H-shaped beam 4: Upper flange 5: Lower flange 6: Web 7: Upper diaphragm 8: Lower diaphragm 9: Pad 10: Hole

Claims (2)

Column-beam connection structure of welded assembly box-shaped column with built-in diaphragm and H-shaped beam, and beam-beam connection structure of welded-assembled box-shaped column with built-in diaphragm and filled with concrete and H-shaped beam In the column, the length in the beam width direction is at least twice as long as the beam web thickness on the beam axis and on the beam axis and at a distance of 1/10 or more of the column diameter from the column cross section to the beam side. A beam-to-column connection structure of a welded assembled box-shaped column with a built-in diaphragm and an H-shaped beam. 2. The beam-to-column connection structure of a welded assembled box-shaped cross-section column with a built-in diaphragm and an H-shaped cross-section beam according to claim 1, wherein the shape of the hole is circular.

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