JP2000096708A - Beam-column joint structure - Google Patents

Abstract

(57) [Problem] To provide a beam-column joint structure capable of reducing a possibility that a beam flange is broken due to a crack or a crack from a corner portion of a beam. SOLUTION: This bracket 3 has an H-shaped cross section. The width of the upper and lower flanges 4 (plates) gradually increases from the beam 2 side to the circular steel tube column 1 side. The gradually increasing portion has an arc shape. The end on the beam 2 side has the same dimensions as the beam 2. The end of the circular steel tube column 1 side is
It forms a circular arc in contact with the outer surface of the circular steel tube column 1. Beam 2
Is joined by a splice plate 6 at the web,
The flange 4 is joined by welding. Round steel pipe column 1
Are joined by welding and further smoothed by a grinder or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a beam-column joint structure between a circular steel pipe column and an H-shaped steel beam.

[0002]

2. Description of the Related Art Conventionally, in a beam-column joint consisting of a circular steel pipe column and an H-shaped steel beam, as a means for reliably transmitting an axial force from a beam flange to a steel pipe section, a column portion is generally provided with an outer diaphragm or a through-hole. A diaphragm or the like is provided to reinforce the beam-column joint (FIGS. 14 to 17). As a means for reinforcing a column-beam joint without applying a stiffener such as a diaphragm to the column-beam joint, the thickness of the column material at the column-beam joint is increased to about 10 in terms of the steel pipe diameter ratio, There is a method of increasing the out-of-plane resistance of the part (FIGS. 18 and 19).

FIGS. 18 and 19 show an example in which the thickness of a steel pipe portion at a beam-column joint is increased to strengthen the joint. In this column-beam joint type, the end of the beam flange is processed into an arc shape according to the shape of the column outer shape, and is welded to the column.

FIG. 20 shows an example of a conventional beam-column joint of the outer diaphragm type. The diaphragm of the outer diaphragm is often shaved from the viewpoint of design, and specifically, as shown in FIG. 21, specifically, a minimum surplus length (h) necessary for welding the outer diaphragm to the column steel pipe is left. It is general that the beam ends A and B are details connected by a straight line.

Here, it is assumed that beams B1 and B2 receive equal tensile forces P1 and P2 at the column-to-column joint of the outer diaphragm type shown in FIG. in this case,
The flow of force from the beam flange first flows into the steel pipe portion and the diaphragm, respectively, and is transmitted to the opposite beam flange.

Here, the assumed base points of the diaphragm destruction are 1) a corner, a point A, and 2) a point where the diaphragm is minimized, a point C (see FIG. 21).

In particular, since stress concentrates locally at the corners and at the point A, there is a high possibility that the point A will be the starting point of destruction. Therefore, there is a contrivance for finishing the inside corner of the point A so that r ≧ 10.

[0008]

However, even if only point A is r ≧ 10, the magnitude of the force wrapping around the diaphragm does not change. Therefore, if h is small due to the diaphragm, breakage occurs at point C in FIG. It is feared that.
Therefore, when a large tensile or compressive force is applied so that the entire cross section of the beam flange yields, there is a problem that the beam end becomes a base point of cracks and cracks, and the beam flange may be broken.

The present invention has been made in view of such a problem, and an object of the present invention is to reduce the possibility of a beam flange being broken due to a crack or a crack from a beam entering corner. It is in providing a beam-column joint structure.

[0010]

SUMMARY OF THE INVENTION The present invention has the following arrangement to solve the above-mentioned problems. The gist of the invention according to claim 1 is a beam-column joint structure for joining a circular steel tube column and a beam, wherein the width gradually increases from the beam side toward the circular steel tube column side, and An end portion is joined by a bracket having a plate having an arc shape in contact with an outer side surface of the circular steel tube column. The gist of the invention according to claim 2 resides in the column-beam joint structure according to claim 1, wherein a portion where the width of the plate gradually increases has an arc shape. Claim 3
The gist of the present invention resides in the beam-column joint structure according to claim 1 or 2, wherein the arc radius r is obtained by the following equation.

B: beam width, D: steel pipe diameter The gist of the invention described in claim 4 is that the minimum value X of the length of the bracket is obtained by the following formula. 3. The beam-column joint structure according to any one of 3.

The gist of the invention according to claim 5 is that when the beams are joined in two or more directions, the ends of the beams on the circular steel tube column side are separated from each other. The present invention lies in the column-beam joint structure according to any one of claims 1 to 4.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the column-beam joint structure according to the present embodiment comprises a circular steel pipe column 1 and a beam 2 (H-section steel).
And a beam-and-column joint structure for joining the two, and are joined by the bracket 3. Therefore, no diaphragm is fixed to the circular steel pipe column 1. FIGS. 1 to 3 show an example in which a hollow steel pipe column having a diameter-to-thickness ratio of a column steel pipe of about 10 is used.

The bracket 3 has an H-shaped cross section. The width of the upper and lower flanges 4 (plates) gradually increases from the beam 2 side to the circular steel tube column 1 side. The gradually increasing portion has an arc shape. The end on the beam 2 side is the beam 2
It has the same dimensions as. The end on the circular steel pipe column 1 side forms an arc that contacts the outer surface of the circular steel pipe column 1. The beam 2 is joined to the beam 2 by a splice plate 6, and the flange 4 is joined by welding. The circular steel pipe column 1 is joined by welding and further smoothed by a grinder or the like.

As shown in FIG. 3, the circular steel pipe column 1 is thickened on the inner diameter side. In FIG. 3, the right side of the circular steel pipe column 1 with respect to the paper surface is a vertical sectional view.

Since the beam-column joint structure according to the embodiment is configured as described above, the following effects can be obtained.

In order to examine the effect of the present invention, the stress concentration of the conventional detail and the detail according to the present invention was investigated by three-dimensional elasticity analysis.

FIGS. 7 and 8 show an analysis model according to the prior art.
9 and 10 show an analysis model according to the present invention.

The two analytical models have shapes assuming that the beam 2 and the flange 4 are welded to the circular steel pipe column 1 having a thicker joint. The difference between the two models is beam 2
Is only the shape of the end.

The analysis conditions were such that both ends of the column were restrained and a load corresponding to the yield load on the entire surface of the beam 2 was applied to the flange 4 of the beam 2 as an axial force.

FIG. 11 shows stress distribution contours according to the prior art.
FIG. 12 shows stress distribution contours according to the present invention.

Since the stress contour using the end detail of the beam 2 of the prior art shown in FIG. 11 is dense at the base of the steel pipe and the beam 2, that is, at the end of the beam 2, the stress is most concentrated on this portion. As can be seen, the maximum principal stress reaches about 2.5 times the general portion of the flange 4 of the beam 2 at the highest point of the contour line.

On the other hand, in the end detail of the beam 2 according to the present invention, the contour line of the stress distribution is gentle as shown in FIG. 12, and it is not apparent that the stress is locally concentrated on the edge of the beam 2. The maximum principal stress level is about 1.5 times the general portion of the flange 4 of the beam 2 at the highest point of the contour line.
Further, since the peak of the stress contour line is shifted from the edge of the beam 2 toward the flange 2 of the beam 2, cracks at the edge of the beam 2
It turns out that it is advantageous for cracking. That is, in the beam-column joint structure according to the present embodiment, the maximum stress portion can be prevented from being generated in the welded portion.

(Embodiment) FIG. 13 shows an example of a beam-column joint of a rigid frame composed of a circular steel tubular column 1 and an H-section steel. The circular steel pipe column 1 has a steel pipe diameter / thickness ratio increased to about 10 at a beam-column joint. Further, no diaphragm is provided in the steel pipe portion.

The beams 21 and 22 are welded to the circular steel tube column 1 via brackets 31 and 32.

In FIG. 13, the beam 21 on the left side is a case where the beam width is larger than the diameter of the circular steel tubular column 1 and the beam 21 on the right side is
2 is a case where the beam width is smaller than the diameter of the circular steel tube column 1.

The flanges 41, 4 of the brackets 31, 32
Reference numeral 2 denotes a plate having an arc for reducing stress at the ends of the beams 21 and 22. The centers of the circular arcs of the flanges 41 and 42 are on a line having an angle of 45 degrees with the beam 2 axis direction from the center point (point O) of the circular steel tube column 1, that is, points B1 and B2. Further, the arc of the flange 41 is defined by the points A1 and C1.
Are the contact points between the column steel pipe and the beam 21, respectively.
Similarly, in the arc of the flange 42, the points A2 and C2 are contact points between the column steel pipe and the beam 22, respectively.

The radius (r) of the circular arc of the flanges 41 and 42 in FIG. 1 and the minimum value (L) of the total length of the plate have the following relationship.

[0028]

(Equation 1)

[0029]

(Equation 2)

It should be noted here that the welding position of the flange of the beam 21 and the flange 41 of the bracket 31 (C1-
C1 ′) must be greater than or equal to the minimum plate lengths L1 and L2. That is, in FIG. 13, the welding position (X: minimum value of the length of the bracket) of the flange of the beam 21 and the flange 41 of the bracket 31 from the face surface of the column flange 41 must be X ≧ L1. The same applies to the portion indicated by reference numeral L2 in the figure.

In the present embodiment, the beam 2 is an H-section steel, but the present invention is not limited to this, and can be applied to a section steel suitable for applying the present invention. In such a case, the shape of the bracket may be adapted.

FIGS. 4 to 6 show a state in which concrete C is cast on steel pipe columns. In such a case, a similar effect can be obtained.

When the beams are joined in two or more directions, it is preferable that the ends of the beams on the circular steel tube column side are separated from each other.

The number, position, shape, and the like of the above-mentioned constituent members are not limited to the above-described embodiment, but can be set to a number, position, shape, and the like suitable for carrying out the present invention.

In each of the drawings, the same components are denoted by the same reference numerals.

[0036]

As described above, according to the present invention, the beam end and the circular steel pipe column are connected by the bracket whose width gradually increases at the joint between the connection part thickened steel pipe and the H-shaped beam. It is possible to reduce the concentration of stress acting on the connection portion to the column, and as a result, it is possible to prevent the beam flange (bracket) from breaking from the corner.

[Brief description of the drawings]

FIG. 1 is a plan view of a joint between a hollow steel pipe and a beam according to an embodiment of the present invention.

FIG. 2 is a perspective view of a joint shown in FIG.

FIG. 3 is a partial vertical sectional view of a joint shown in FIG. 1;

FIG. 4 is a plan view of a joint between a concrete-filled steel pipe and a beam according to the embodiment of the present invention.

FIG. 5 is a perspective view of a joint shown in FIG. 4;

FIG. 6 is a partial vertical sectional view of a joint shown in FIG. 4;

FIG. 7 is a plan view of an analysis model of a beam-column joint according to the related art.

8 is a perspective view of the analysis model shown in FIG.

FIG. 9 is a plan view of an analysis model of a beam-column joint according to the present invention.

FIG. 10 is a perspective view of the analysis model shown in FIG. 9;

FIG. 11 is a plane stress distribution diagram of the analysis model shown in FIGS. 7 and 8;

FIG. 12 is a plane stress distribution diagram of the analysis model shown in FIGS. 9 and 10;

FIG. 13 is a plan view showing a joint between a hollow steel pipe and a beam according to an example of the present invention.

FIG. 14 is a sectional view (column upper surface) of a beam-column joint (outer diaphragm type) according to a conventional technique.

FIG. 15 is a cross-sectional view (column side) of a beam-column joint (outer diaphragm type) according to a conventional technique.

FIG. 16 is a cross-sectional view (upper surface of a column) of a beam-column joint (through-diaphragm type) according to a conventional technique.

FIG. 17 is a cross-sectional view (column side) of a beam-column joint (through-diaphragm type) according to a conventional technique.

FIG. 18 is a cross-sectional view (column upper surface) of a column-to-column joint of a beam-to-column connection thickened steel pipe according to a conventional technique.

FIG. 19 is a cross-sectional view (column side) of a column-to-column joint of a beam-to-column connection thickened steel pipe according to a conventional technique.

FIG. 20 is an example of an outer diaphragm type according to the related art.

FIG. 21 is an enlarged view of FIG. 20;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circular steel pipe column 2, 21, 22 Beam (H-section steel) 3, 31, 32 Bracket 4, 41, 42 Flange (plate) 5 Web 6 Splice plate C Concrete

Claims (5)

[Claims] 1. A column-beam joint structure for joining a circular steel pipe column and a beam, wherein the width gradually increases from the beam side toward the circular steel pipe column side, and the end on the circular steel pipe column side is A beam-column joint structure characterized by being joined by a bracket having an arc-shaped plate in contact with an outer surface of a circular steel tube column. 2. The beam-column joint structure according to claim 1, wherein the portion where the width of the plate gradually increases has an arc shape. 3. The beam-column joint structure according to claim 1, wherein the arc radius r is obtained by the following equation. (Equation 1) B: beam width, D: steel pipe diameter 4. The beam-column joint structure according to claim 1, wherein the minimum value X of the length of the bracket is obtained by the following equation. (Equation 2) 5. The method according to claim 1, wherein when the beams are joined in two or more directions, ends of the beams on the circular steel tube column side are separated from each other. 2. The beam-column joint structure according to item 1.