JPH05302358A - Reinforcing structure for joint between column and beam - Google Patents

Abstract

PURPOSE:To prevent the occurrence of rupture owing to breakage of the weld part of a beam end, in a column beam joint by welding. CONSTITUTION:The end part of a beam 2 is joined with a flange 1b of a column 1 by welding. A vertical stiffener 3 is mounted in a position spaced away from the end of the beam 2 by a given distance. The flange 1b of the column 1 and the vertical stiffener 3 are intercoupled through bolts 4 arranged in the vicinity of upper and lower flanges 2b and 2c of the beam 2 and locked together by means of a nut 5. The bolt 4 resists against only stretch and does not substantially resist against compression. As a result, the neutral axis of the beam 2 at the part approaches the stretch side against a repeat force. A tensile stretch at the flange 2b (or 2c) at the part is reduced, and collapse of the weld part of the beam end ahead of local buckling of the beam 2 is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing structure for preventing breakage of beam-end welded portions of beam-column joints due to cracking.

[0002]

2. Description of the Related Art In columns or beams constituting a frame of a structure, or piles used as a foundation, stiffeners or reinforcing ribs are provided at portions receiving a large bending moment to stiffen or buckle as a member. When there is a risk, it is common practice to provide reinforcing ribs or the like to increase the rigidity. In such conventional buckling stiffening by the reinforcing ribs, the reinforcing ribs are provided at required intervals and the buckling length is shortened to improve the strength against buckling.

[0003]

Due to the seismic design, it is considered that the beam is subjected to large cyclic plastic deformation. In addition to the problem of local buckling and deformation capacity of the compression side flange, the beam-column joint is welded. In some cases, cracking of the beam end welds of the pull side flange becomes a significant problem.

On the other hand, the conventional stiffener provided for the purpose of stiffening buckling does not contribute to the reduction of stress in the beam end welded portion, so that the beam end welded portion precedes the local buckling of the beam. There is a possibility of destruction.

The present invention is intended to solve the above-mentioned problems in a conventional beam-column joint by welding.

[0006]

In the reinforcing structure of the present invention,
A tensile resistance material is provided near the beam flange at the beam end of the beam for the purpose of preventing cracks due to pulling of the beam end welded portion of the beam-column joint.

The tensile resistance material is, for example, a bolt that connects the fixing member near the material end of the beam and the column, and is provided in parallel on the upper and lower flange sides, assuming either repetitive force, or depending on the case, one of them is used. But it's okay. Also, if there are beams on both sides of the pillar, a fixing member is provided at a position spaced from the end of the beam by a predetermined distance, and a long tensile resistance material penetrating the pillar is used to fix the fixing members on both sides of the beam. You may connect.

As another aspect, a fixing member such as a vertical stiffener is arranged in a portion near the beam end, and a tensile resistance material such as a bolt is arranged in parallel with the flange either vertically or vertically between the fixing members. By connecting with, it is possible to prevent cracks at the beam end welds. In this section, by providing the tensile resistance material in parallel with the flange of the beam, the neutral axis of bending approaches the tensile side, and the tensile strain due to bending becomes smaller than the compressive strain. This effect extends to the welded portion of the beam end and cracks are less likely to occur. In this case, the smaller the distance between the section where the tensile resistance material is arranged and the beam end joint is, the more effective it is, and the distance can be separated to some extent, but the distance is preferably about the flange width B.

In each of the above embodiments, a bolt is used as the tensile resistance material, and the fixing member and the pillar or the fixing members are connected by tightening the bolt with the nut, so that the bolt resists only the tensile force and compresses. Do not resist force. In addition, pre-stress can be applied to the connecting section by tightening a nut or the like, but pre-stress need not be introduced.

As the fixing member, a plate-shaped vertical stiffener provided between the upper and lower flanges can be used. Alternatively, a rib plate or the like provided near the flange may be used,
It is not particularly limited.

Further, the tensile resistance material is not limited to the bolt, and flat bar steel or the like may be used. Since the tensile resistance material in the present invention is not intended to share the force on the compression side, when both ends of the flat steel bar are fixed to the fixing member, the tensile resistance material is not joined to the beam web or the plate thickness is reduced. By causing buckling at an early stage by such means, the neutral axis of bending can be brought close to the tension side.

[0012] It is effective to use high tensile steel as the tensile resistance material such as bolts and flat bar steel for the purpose of suppressing tensile strain even after the plastic end is greatly plasticized at the beam end.

On the other hand, in the reinforcing structure of the present invention, the compressive strain is large as compared with the case where the bending neutral shaft approaches the tensile side flange and the tensile strain becomes small. With respect to this point, it is conceivable to improve the deformation performance of the beam due to local buckling of the compression flange by reinforcement or stiffening in this section in which the material end is likely to be plasticized.

As one of the means, there is a method of arranging vertical stiffeners at a narrow interval in this section to suppress deterioration of proof stress of the compression flange. Instead of the vertical stiffener, rib plates may be arranged at the corners between the flanges of the beams and the webs. Further, as another means, there is a method of reinforcing or stiffening the web of the beam so as to form a good plastic hinge in which proof stress is not easily deteriorated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The illustrated embodiment will be described below.

FIGS. 1 (a) and 1 (b) show an embodiment of the reinforcing structure of the present invention. In order to prevent cracks at the end welds of the beam 2 at the beam-column joint, the beam 2 The vertical stiffener 3 provided as a fixing member and the flange 1b of the column 1 are connected by bolts 4 as tensile resistance materials that are brought close to the upper and lower flanges 2b and 2c of the beam 2, and are fixed by nuts 5. ..

When a repetitive force such as an earthquake is applied, the beam 2
The bending of the bolts 4 causes the tensile force and the compressive force to be alternately applied to the bolts 4 close to the upper and lower flanges 2b and 2c.
Resists only tension and does not substantially resist compression. Therefore, the neutral axis of the beam 2 approaches the pulling side at this portion, and the flange 2 on the pulling side is more than the cross section simply increased.
The tensile stress in b (or 2c) is reduced, so that the tensile strain can be suppressed to a small value.

In this embodiment, both the pillar 1 and the beam 2 are made of H-shaped steel, and the bolts 4 are arranged on both sides of the web 2a of the beam 2 respectively above and below. The column 1 can also be applied to the case of a square steel pipe column or the like, and in that case, the vertical stiffener 3 of the beam 2 and the pipe wall of the square steel pipe column may be connected by a bolt 4.
In the figure, 6 is a groove for welding provided at the end of the beam 2.

FIGS. 2 (a) and 2 (b) show another embodiment of the reinforcing structure of the present invention, which is used as a fixing member at a predetermined position of an end portion of a beam 2 welded to both sides of a rectangular steel pipe column 1. The vertical stiffener 3 is provided, and these are connected by long bolts 7 penetrating the pillar 1.

FIGS. 3 (a) and 3 (b) show still another embodiment of the present invention, in which vertical stiffeners 3a, 3b are provided near the material end of the beam 2 at predetermined intervals, The bolts 4 are arranged in parallel with the upper and lower flanges 2b and 2c of the two. As in the case of the embodiments of FIGS. 1 (a), 1 (b) and 2 (a), 2 (b),
Since the bolt on the compression side does not bear the axial force, the neutral axis of the beam 2 moves to the tension side at this portion, and the strain on the tension side is kept small. Therefore, as shown in the figure, if the beam end portion and the portion where the bolt 4 is arranged are sufficiently close to each other, the beam end joint portion is also affected, and cracking of the welded portion due to tension can be prevented.

FIGS. 4 (a) and 4 (b) show an example in which flat bar steel is arranged in place of bolts (however, different embodiments are divided into the left side and the right side of the drawing and shown in the same drawing). Exist). On the left side of the figure, a flat steel bar 8 serving as a tensile resistance material is arranged with its edge cut off from the web 2a of the beam 2 so that it compressively buckles above a certain level to intentionally reduce the load of compressive stress. .. Further, on the right side, the flat bar steel 9 as a tensile resistance material is arranged in the form of a horizontal stiffener without cutting the edge with the web 2a, but by reducing the plate thickness for the same reason,
It is designed to buckle under compression and reduce the burden of compressive stress. For these flat bar steels 8 and 9, it is more effective if high-strength steel is used.

In the embodiments of the present invention described above, the tensile strain is reduced by disposing the tensile resistance material made of bolts or flat bar steel, but the compressive strain is increased instead. In this regard, since the region that plasticizes quickly is the vicinity where the tensile resistance material is placed,
It can be devised to improve plastic deformation performance.

FIGS. 5 (a) and 5 (b) show one example thereof. In the reinforcing structure corresponding to the embodiment of FIGS. 3 (a) and 3 (b), the vertical stiffener 10 is provided in the section where the bolts 4 are arranged. By providing them at small intervals, the beam 2 is reinforced and the deformation performance of this portion is improved.

FIGS. 6 (a) and 6 (b) show another example. In the reinforcing structure corresponding to the embodiment of FIGS. 1 (a) and 1 (b), the web 2a in the section where the bolts 4 are arranged is shown. Is reinforced by the plate 11. In this case, the plate 11 may be welded to the web 2a, but it is fixed to the web 2a by, for example, a bolt passed through a loose hole to restrain the deformation of the web 2a in the out-of-plane direction, and the plasticity of the beam 2 at this portion is restrained. It is also possible to improve the deformability.

[0025]

According to the reinforcing structure of the present invention, in a beam-column joint by welding, it is possible to effectively prevent the beam end weld from breaking prior to the local buckling of the beam due to bending. it can.

In connection with the above, it is possible to improve the plastic deformation capacity of the beam, and it is possible to design in consideration of plastic deformation.

All or part of the reinforcing member can be attached to the beam in advance, and there is little influence on workability and cost at the site, and it is a rational and economical reinforcing structure.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a front view and (b) is a horizontal sectional view.

2A and 2B show another embodiment of the present invention, in which FIG. 2A is a vertical sectional view and FIG. 2B is a horizontal sectional view.

FIG. 3 shows still another embodiment of the present invention,
(a) is a front view and (b) is a horizontal sectional view.

FIG. 4 shows an embodiment in which a flat steel bar is used as a tensile resistance material, (a) is a front view and (b) is a horizontal sectional view.

5A and 5B show an example of means for coping with an increase in strain on the compression side, where FIG. 5A is a front view and FIG. 5B is a sectional view taken along line AA.

6A and 6B show another example of means for coping with an increase in strain on the compression side, in which FIG. 6A is a front view and FIG. 6B is a BB sectional view thereof.

[Explanation of symbols]

1 ... Pillar, 2 ... Beam, 3 ... Stiffener, 4 ... Bolt, 5 ...
Nut, 6 ... Groove, 7 ... Long bolt, 8, 9 ... Flat steel bar, 10 ... Stiffener, 11 ... Plate

Claims (6)

[Claims] 1. A fixing member is provided at a position spaced apart from a material end of the beam at a column-beam joining portion by joining the ends of the beam having flanges above and below the web to the column by welding. A reinforcement structure for a column-beam joint, wherein the column and the fixing member are connected to each other by a tensile resistance material that extends in the longitudinal direction near the flange of the beam. 2. The reinforcement structure for a beam-column joint according to claim 1, wherein the tensile resistance material is a bolt that penetrates the plate element and the fixing member that form the column. 3. A column-beam joint formed by welding the ends of a beam having flanges above and below the web to the column, at predetermined intervals in the longitudinal direction of the beam at the ends of the beam. A reinforcing structure for a beam-column joint, wherein a fixing member is provided in advance, and the fixing members are connected to each other by a tensile resistance material that extends in the longitudinal direction in the vicinity of the flange of the beam. 4. A column-beam joint formed by welding the ends of beams having flanges above and below the web to the columns by welding from the ends of the beams located on both sides of the column. A column-beam joint, wherein fixing members are provided at positions spaced apart from each other, and the fixing members are connected to each other by a tensile resistance material that penetrates through the columns and extends in the longitudinal direction in the vicinity of the flange of the beams. Reinforcement structure. 5. The reinforcement structure for a column-beam joint according to claim 3, wherein the tensile resistance material is a bolt penetrating the fixing member. 6. The reinforcement of a beam-column joint according to claim 1, wherein a stiffening plate is attached to the web of the beam in the section where the tensile resistance material is provided. Construction.