JP2006214239A - Beam-column semi-rigid connection structure and steel frame structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam-column semi-rigid connection structure which is excellent in strength and rigidity, and implemented at a low cost, and to provide a steel frame structure. <P>SOLUTION: According to the beam-column semi-rigid connection structure, an end of a steel pipe column 1 is connected to a beam 3 via a connection member 2. A connection portion inclusive of the connection member 2 is constructed as a semi-rigid connection portion, and cross-sectional areas of the steel pipe column 1 and the connection member 2 are set so as to be sufficient for ensuring the elasticity of the steel pipe column 1. The steel pipe column 1 is formed of a square steel pipe column while the connection member 2 is formed of an angle, and the connection member 2, the steel pipe column 1, and the beam 3 are connected to each other by bolting or welding. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structural system that typically joins both ends of a square steel pipe column to a beam using angle steel or the like, and more particularly to a column beam semi-rigid joint structure and a steel structure frame.

  In a building such as a house, a steel structure composed of columns and beams is used. In this type of frame structure, for example, in Patent Document 1, a beam is passed between a column on the upper floor and a column on the lower floor, which is the structural frame of the outer wall, so as to match the size of the opening on the outer wall between the columns on each floor. Thus, there is disclosed a structure in which columns on the upper floor and the lower floor are arranged at arbitrary positions on the beam.

Japanese Patent No. 2992580

  A conventional rigid joint frame in which a column is subjected to a large axial force and bending has a significant decrease in yield strength, and there is a problem that the column collapses as it is. Also, the column cannot be kept elastic during large deformations, and it has not always been easy to ensure strength and rigidity.

  In view of such circumstances, an object of the present invention is to provide a column beam semi-rigid joint structure and a steel structure frame that are particularly excellent in strength and rigidity and that can be realized at low cost.

  The column beam semi-rigid joint structure of the present invention is a joint structure in which an end portion of a steel pipe column is joined to a beam via a joint member, and the joint portion including the joint member is configured as a semi-rigid joint, A cross-sectional size of the steel pipe column and the joining member is set so that the steel pipe column maintains elasticity.

  In the column beam semi-rigid joint structure of the present invention, the steel pipe column is constituted by a square steel pipe, the joining member is constituted by an angle, and the joining member, the steel pipe column and the beam are coupled by bolt fastening or welding. It is characterized by doing.

In the column beam semi-rigid joint structure of the present invention, the steel tube column and the joining member are set to have a cross-sectional size so that a horizontal proof stress of the steel tube column satisfies the following formula.
ΣH <H _y
Here, .SIGMA.H the lateral strength obtained from overturning moment of the steel column at the time of the safety limit, the sum of the flange angle Lateral Strength and Web Angle lateral strength, the H _y is the lateral strength of the steel pipe column converted by stigma position.

  Further, the steel structure frame of the present invention is a multi-span multi-span steel structure frame formed by connecting beams to each other via a steel pipe column, and any one of the above-mentioned column beam semi-rigid joints at least in the middle column part of the frame It has a structure.

  According to the present invention, in an exemplary embodiment, an angle is used at the joint between the beam and the steel pipe column. By determining the angle of the joint and the cross-sectional size of the beam according to a predetermined relational expression, the column can be kept elastic even during large deformations, and necessary strength and rigidity can be ensured. Since the structural system can control the stress generated in the column, not only the mechanical rationality of the column is improved, but also there is a design advantage because the column can be made substantially thin. In addition, by constructing the structure with pillars with semi-rigid joints on both ends that do not require welding, it is possible to realize a structure with excellent performance at a low price without damage to the pillar even in the event of a large earthquake. it can.

Specifically, the column can be kept elastic by designing the flange angle and the web angle as in the above formula, that is, ΣH <H _y .
Moreover, the steel structure frame having the column beam semi-rigid joint structure according to the present invention exhibits extremely stable elasto-plastic behavior.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a structural system composed of a square steel pipe column semi-rigidly bonded at both ends to which the present invention is applied. In this system, angle steel pipe 2 (angle) is used to join both ends of square steel pipe column 1 to beam 3. Each angle steel 2 is fastened to the square steel pipe column 1 or the beam 3 by a bolt 4 in this example.

In the present invention, the joint portion including the angle steel 2 that is a joining member is configured as a semi-rigid joint, and the cross-sectional sizes of the steel tube column 1 and the angle steel 2 are set so that the square steel tube column 1 maintains elasticity. First, in designing a square steel pipe column having a semi-rigid connection, a design formula for a beam joint that keeps the square steel pipe column elastic is derived.
FIG. 2 shows the bending moment (M) distribution acting on the beam-to-column joint of the cantilever column and the column of the square steel pipe. As a method for keeping the column elastic, a rigidity / strength condition at a horizontal displacement δ _{1/30 which} is a safety limit (interlayer deformation angle θ = _1/30 ) is obtained.

Rigidity / strength condition of semi-rigid joint column The rigidity of a semi-rigid joint column is expressed by the sum ΣK of the initial stiffness of the column overturning moment, flange angle and web angle. The strength is evaluated by the sum ΣH of each horizontal proof stress at the safety limit (see formulas (1) and (2)).
ΣK = K _c + K _f + K _w (1)
ΣH = H _{c (1/30)} + H _{f (1/30)} + H _{w (1/30)} (2)
here,
K _c : column rigidity before falling (= K _e / 2, K _e ; elastic rigidity of the column)
K _f; lateral strength H _{f (1/30)} to obtain the overturning moment when the [delta] _1/30;; initial stiffness of the flange angle K _w; initial stiffness H _{c (1/30)} of the web angle [delta] _1/30 when Horizontal angle strength of flange angle H _{w (1/30)} ; Web angle horizontal strength at δ _1/30

Horizontal Strength H _y pillar of strength conditions column is given by the indicating the yield bend moment of the column at the position of (a) was converted to the lateral strength of at stigma position (3) FIG. 2 (b).
H _y = M _y / l ′ (3)
here,
M _y; yield bend moment of the column (consider axial force)
l ': Distance from the stigma to the end of the angle (see Fig. 2 (b))

From the above, the strength condition for keeping the column elastic is given by the following equation (4). This, (2) .SIGMA.H obtained in expression it is meant that the design cross-sectional size of the column and the angle to be below the H _y obtained in (3) below.
ΣH <H _y (4)

Next, as a calculation example, FIG. 3 shows a calculation result when a column of □ = 200 × 200 × 6 (mm) is used. Calculation is performed with t _f = 8 (mm) and 15 (mm) with angle width w _f = w _w = 200 (mm), angle height h _f = 75 (mm), and flange angle thickness t _f as a parameter. It was. The column axial force ratio (axial force / yield axial force) was 0.1, and the yield stress level was σ _y = 320 (N / mm). In FIG. 3, the solid line indicates the result of the column (A) obtained by the equations (1) and (2), and the dotted line indicates the result of the column (B) obtained by the equation (3).

From the graph of FIG. 3, the horizontal proof stress of the column (A) and the column (B) is compared at a displacement δ _{1/30 where the} interlayer deformation angle θ = _1/30 . When t _f = 8 (mm), the column (A) falls below the strength of the column (B) and satisfies the condition of the expression (4). In the case of t _f = 15 (mm), since the column (A) exceeds the strength of the column (B), the column cannot be kept elastic at the position (a) in FIG.

Next, the strength and rigidity of the semi-rigid joint necessary for stabilizing the frame will be described.
In order to investigate the stability of a frame using a semi-rigid joint, an analysis of a steel structure frame with multiple multi-spans, for example two layers and four spans, is performed. FIG. 4 shows an example of an analysis model. The analysis objects are i) a semi-rigid joint frame using semi-rigid joints for all columns, and ii) a mixed frame using semi-rigid joints for corner columns and semi-rigid joints for middle columns. In addition, for comparison and examination with the analysis results of these frames, iii) analysis was also performed for rigid joint frames using rigid joints for all columns.

The cross section of the column is □ = 400 × 400 × 9 (mm), and the cross section of the beam is □ = 600 × 200 × 11 × 17 (mm). For comparison, the cross-sections of the column beams in each frame were the same. The thickness of the flange angle attached to the semi-rigid joint column is t _f = 10 (mm).
The analysis was performed by controlling the displacement of the second layer stigma. Vertical load P _{c (0.3)} with axial force ratio (axial force / yield axial force) 0.3 is applied to the corner column, and vertical load P with axial force ratio (axial force / yield axial force) 0.6 is applied to the central column. _{c (0.6),} it is trisected point of the beam was loading each load P _b from the beams.

From the analysis results, the conditions of strength and rigidity for stabilizing the first-layer stigma displacement without accumulating in one direction are as follows.
ΣF ≧ 0.08ΣP (5)
k _B EI ≧ P (2h) ² / π ² (6)
Where ΣF; horizontal strength of the frame layer ΣP; total vertical load k _B EI; column bending stiffness h;

  FIG. 5 shows the elasto-plastic behavior of each analytical model. The behaviors of the analytical models i) and ii) that satisfy the expressions (5) and (6) are extremely stable. On the other hand, the analysis model iii) does not always provide good stability.

In addition, this invention is not limited only to embodiment mentioned above, It can change and set suitably as needed, and can obtain the effect similar to the said embodiment.
For example, numerical examples such as dimensions shown in the above embodiment are not limited thereto, and various other examples can be adopted. The angle can also be fixed to the column beam by welding.

It is a figure which shows the structural system which consists of a square steel pipe column of both ends semi-rigid joining in embodiment of this invention. It is a figure which shows the bending moment distribution which acts on the column beam junction part and column of the cantilever column of the square steel pipe in embodiment of this invention. It is a figure which shows the example of the calculation result of the pillar in embodiment of this invention. It is a figure which shows the example of the steel structure frame which concerns on this invention. It is a figure which shows the elastoplastic behavior of the analysis model which concerns on embodiment of this invention.

Explanation of symbols

1 Square steel pipe column 2 Angle steel 3 Beam

Claims (4)

A joining structure in which the end of the steel pipe column is joined to the beam via a joining member,
A beam-and-beam semi-rigid joint structure characterized in that a joint portion including the joint member is configured as a semi-rigid joint, and a cross-sectional size of the steel pipe column and the joint member is set so that the steel pipe column maintains elasticity.   The said steel pipe column is comprised by the square steel pipe, and the said joining member is comprised by the angle, The said joining member, the said steel pipe column, and the said beam are couple | bonded by bolt fastening or welding. Column beam semi-rigid joint structure. The column-beam semi-rigid joint structure according to claim 2, wherein a cross-sectional size of the steel pipe pillar and the joining member is set so that a horizontal proof stress of the steel pipe pillar satisfies the following formula.
ΣH <H _y
Here, .SIGMA.H the lateral strength obtained from overturning moment of the steel column at the time of the safety limit, the sum of the flange angle Lateral Strength and Web Angle lateral strength, the H _y is the lateral strength of the steel pipe column converted by stigma position. A multi-span multi-span steel structure frame formed by connecting beams to each other via steel pipe columns,
A steel structure frame having the column beam semi-rigid joint structure according to any one of claims 1 to 3 at least in a middle column part of the frame.

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