JP2003239393A - Steel pipe stiffening brace member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel pipe stiffening brace member having prescribed bearing force without thickening plate thickness, ensuring the accuracy of a clearance between a shaft member and a stiffened steel pipe and relatively easily manufactured. <P>SOLUTION: This steel pipe stiffening brace member has a stiffened steel pipe formed of a rectangular steel pipe, and a shaft member passed through in the stiffened steel pipe to bear axial force. The shaft member has a plate-like main shaft member with both side edge parts facing the opposed corner parts of the stiffened steel pipe, and sub-shaft members installed at the side faces of the main shaft member and spaced by a prescribed distance from the inner surface of the stiffened steel pipe. Further, the side edge parts of the main shaft member abut on the corner parts of the stiffened steel pipe directly or through liners. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe stiffening brace material stiffened by a steel pipe, which is mainly used as a structural member for construction and civil engineering and which is excellent in plastic deformation capacity and seismic energy absorption capacity. .

[0002]

2. Description of the Related Art A brace material in which a shaft material made of flat steel is supported through a stiffening steel pipe has a simple structure, but it has excellent seismic energy absorption performance not only in the tensile direction but also in the compression direction. Therefore, various proposals have been made and adopted in the fields of construction and civil engineering.

As an example of such a brace material, for example, Japanese Patent Laid-Open No. 7-324377 (hereinafter referred to as Prior Art 1)
There is an invention described in). The unbonded steel frame brace stiffened by the steel pipe according to the present invention prevents the buckling of the shaft member by inserting the shaft member having an H-shaped or cruciform cross section into the stiffened steel pipe having a circumscribed outer diameter. It was done.

Also, for example, Japanese Patent Laid-Open No. 11-172783.
A brace member according to the invention described in Japanese Patent Publication (hereinafter referred to as "prior art 2") adjusts a gap between a flat steel that is a shaft material and a corresponding corner of a rectangular steel pipe that is a stiffening steel pipe. A lubricous liner is inserted between the two to enhance the stiffening effect of the square steel pipe, and at the same time prevent friction noise when both slide.

[0005]

In the prior art 1, since the stiffening effect of the stiffening steel pipe on the shaft member is greatly influenced by the size of the gap between the stiffening steel pipe and the shaft member, the size of the gap is large. Is required to be about 1/10 to 1/20 of the plate thickness of the shaft material. However, when the shaft material is flat steel, it is relatively easy to control the clearance accuracy because there are two locations where the clearance faces each other. Since there are four locations, there is a problem that it is extremely difficult to control the gap accuracy. In particular, there is a problem in that it is extremely difficult to insert the shaft material into the stiffened steel pipe in a state where the accuracy of the gaps at the four places is guaranteed.

Further, the prior art 2 solves the above-mentioned problems of the prior art 1, but since the shaft member is made of flat steel, the yield strength may be insufficient. For this reason, if it is attempted to have the same yield strength as the shaft material with a cross-shaped cross section, the plate thickness of the flat steel itself must be increased, and the plate thickness of the gusset plate for joining to the columns and beams must be increased accordingly. Therefore, there is a problem that the frame weight increases, the material cost of the member increases, the manufacturing cost of the member increases, and the construction cost of the member increases.

The present invention has been made in order to solve such a problem, has a predetermined proof stress without increasing the plate thickness, and ensures the accuracy of the gap between the shaft material and the stiffening steel pipe. It is an object to obtain a steel pipe stiffening brace material that is guaranteed and can be manufactured relatively easily.

[0008]

MEANS FOR SOLVING THE PROBLEMS A steel pipe stiffening brace material according to the present invention is as follows. (1) A steel pipe stiffening brace material having a stiffening steel pipe made of a rectangular steel pipe and a shaft member penetrating the stiffening steel pipe to bear an axial force, wherein the shaft member has both side edges It is characterized in that it has a plate-shaped main shaft member facing the opposite corners of the stiffening steel pipe, and a sub-shaft member installed on the side surface of the main shaft member through a gap with the inner surface of the stiffening steel pipe. is there.

(2) In the above (1), the entire length or part of both side edge portions of the main shaft member abut on the opposite corner portions of the stiffening steel pipe. (3) In the above (1), both side edge portions of the main shaft member are arranged at opposing corner portions of the stiffening steel pipe with a gap therebetween,
A liner plate is inserted in the gap.

(4) In the above (1) to (3),
It is characterized in that the shaft member has a cross-shaped cross section or a T-shaped cross section. (5) In the above (1) to (3), the cross section of the shaft member is of a scalene cross shape, and the inner dimension of the main shaft member is 6.5 times or less the plate thickness of the main shaft member, The inner dimension of the shaft member is 5.5 times or less the plate thickness of the auxiliary shaft member. (6) In the above (1) to (3), the cross section of the shaft member is an isosceles cross shape, and the cross sectional area of the main shaft member is 1.5 times or more the cross sectional area of the sub shaft member. It is characterized by that.

(7) In the above (1) to (5),
The cross-sectional area of the main shaft material is 45% or less of the total cross-sectional area of the shaft material, and the stress increase rate of the steel material forming the main shaft material is 1.3 or more. (8) In the above (1) to (7), the proof stress of the joining member installed at the longitudinal end portion of the shaft member is 1.2 times or more the proof stress of the longitudinal center portion of the shaft member. It is characterized by.

(9) In the above (1) to (8),
The joining member installed at the longitudinal end portion of the shaft member has a substantially cross-shaped cross-sectional shape, and the side edge portion of the joining member is directly or through a liner plate to a corner portion of the stiffening steel pipe. It is characterized by abutting. (10) In the above (1) to (9), the steel material forming the main shaft material is made of low yield point steel.

According to the present invention, the shaft member has the main shaft member and the auxiliary shaft member provided on the main shaft member, so that the shaft member has a predetermined yield strength without increasing the plate thickness of the main shaft member. Furthermore, in a state where the rectangular steel pipe which is a stiffening steel pipe is elastically flattened, a shaft material is inserted into the rectangular steel pipe, and thereafter, the rectangular steel pipe is returned to its original shape to facilitate the insertion, This facilitates management of the clearance accuracy between the side edge of the shaft member and the corner of the rectangular steel pipe.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a sectional view of a steel pipe stiffening brace material according to a first embodiment of the present invention. In FIG. 1, (a) shows a stiffened steel pipe having a substantially square cross-section, and an unequal cross-shaped cross-section in which a shaft member is welded and joined,
(B) is an equilateral cross section in which the stiffening steel pipe has a substantially square cross section and the shaft material is integrally molded, and (c) is an equilateral cross shape in which the stiffening steel pipe has a substantially rhombic cross section and the shaft members are welded and joined. The cross section of the mold is shown in (d), which is an equilateral cross-shaped cross section in which the stiffening steel pipe has a substantially rhombic cross section and the shaft member is integrally molded. (E) has a substantially rhombic cross section of the stiffening steel pipe and has an approximately equilateral cross-shaped cross section in which a shaft material having a T-shaped cross section is welded, and (f) shows a stiffening steel pipe having a substantially rhombic cross section and a T-shaped cross section Is an equilateral substantially cross-shaped cross section in which a rod-shaped shaft member is integrally molded.

In FIG. 1 (a), 10 is a stiffened steel pipe having a substantially square cross section, 20 is a shaft member, 21 is a main shaft member constituting the shaft member 20, 22 is a sub-shaft member constituting the shaft member 20, and 23 Is a joint for joining the main shaft member 21 and the sub shaft member 22. And
Between the side edge a of the main shaft member 21 and the corner e of the stiffening steel pipe 10,
A gap 30 of a predetermined size (for example, 1/15 of the plate thickness of the main shaft member 21) is secured between the side edge C of the main shaft member 21 and the corner G of the stiffening steel pipe 10. There is.
On the other hand, between the side edge portion B of the sub shaft member 22 and the corner portion of the stiffening steel pipe 10, and between the side edge portion D of the sub shaft member 22 and the corner portion of the stiffening steel pipe 10, respectively. A gap 40 of a predetermined size (for example, a portion corresponding to the plate thickness of the main shaft member 21) is secured.

Therefore, the proof stress of the shaft member 20 is
Since the out-of-plane deformation of No. 1 is constrained by the auxiliary shaft member 22, a predetermined value can be secured without increasing the wall thickness. This is because the buckling waveform of the main shaft member 21 constrained by the sub-shaft member 22 is larger than that of the main shaft member 21 only, and the force for deforming the stiffened steel pipe 10 is also reduced. . Furthermore, when the stiffening steel pipe 10 is elastically deformed to a flat shape and the distance between the corner e and the corner g is enlarged, the gap 30 is enlarged and the gap 40 also maintains a considerable size. The shaft member 20 can be easily inserted into the shaft 10. Therefore, in the stiffening steel pipe 10, the shaft member 2
It is not necessary to set the size of the gap 30 just to enable or facilitate the work of inserting 0. Therefore, the size of the gap 30 can be set to a predetermined value or the side edge portion of the main shaft member 21 can be brought into contact with the corner portion of the stiffening steel pipe 10 without being restricted by the above. The stiffening effect of the stiffening steel pipe 10 on the shaft member 20 is increased.

In FIG. 1 (b), reference numeral 50 denotes a shaft material, and the main shaft material 21 and the auxiliary shaft material 22 in FIG. 1 (a).
Is integrally molded. The same parts as those in FIG. 1A are designated by the same reference numerals, and a part of the description is omitted. Therefore, also in FIG. 1B, the same operation and effect as in FIG. 1A can be obtained.

In FIG. 1 (c), 60 is a stiffened steel pipe having a substantially rhombic cross section, 70 is a shaft member, 71 is a main shaft member that constitutes the shaft member 70, 72 is a sub-shaft member that constitutes the shaft member 70, and 73 Is a joint between the main shaft member 71 and the sub shaft member 72. And the main shaft material 71
Between the side edge of the stiffening steel pipe 60 and the corner of the stiffening steel pipe 60, and between the side edge of the main shaft 71 and the corner of the stiffening steel pipe 60.
A gap 80 of a predetermined size (for example, the main shaft 7
1/15 of the plate thickness of 1) is secured. On the other hand, between the side edge portion of the sub-shaft member 72 and the corner portion of the stiffening steel pipe 60, and between the side edge portion of the sub-shaft member 72 and the corner portion of the stiffening steel pipe 60, respectively. A gap 90 having a predetermined size (for example, a portion corresponding to the plate thickness of the main shaft member 71) is secured. Therefore,
As in the case of FIG. 1 (a), a predetermined value is secured for the proof stress of the shaft member 70, and the shaft member 70 can be easily inserted into the stiffening steel pipe 60 to stiffen the shaft member 70. The stiffening effect of the steel pipe 60 is increased.

In FIG. 1 (d), 100 is a shaft material, and the main shaft material 71 and the auxiliary shaft material 7 in FIG. 1 (c).
2 is integrally molded. In addition, FIG. 1 (c)
The same parts as those are denoted by the same reference numerals, and part of the description will be omitted. Therefore, also in (d) of FIG. 1, the same operation and effect as in (c) of FIG. 1 can be obtained.

In addition, in (a) to (d) of FIG.
The shaft members 20, 50, 70, 100 have a substantially cruciform cross section, but the first embodiment is not limited to this, and the main shaft member is provided with the auxiliary shaft member only on one surface thereof (substantially T). Cross section), size of a pair of counter shafts (length or thickness, etc.)
May not be the same but may be asymmetric, or a plurality of sub-shafts may be installed on one or both surfaces of the main shaft. The stiffening steel pipe may have a substantially rhombic cross section and the shaft member may have a unequal cross-shaped cross section. Further, the main shaft material of the shaft material may be arranged at either a long diagonal position or a short diagonal position of the substantially rhombic cross section. Further, the main shaft member may be longer or shorter than the sub shaft member.

In FIG. 1 (e), 110 is a stiffened steel pipe having a substantially rhombic cross section, 150 is a shaft member, 151 is a main shaft member constituting the shaft member 150, and 152 is a T-shaped cross section constituting the shaft member 150. A sub shaft member 153 is a joint between the main shaft member 151 and the sub shaft member 152. A predetermined distance is provided between the side edge portion of the main shaft member 151 and the corner portion of the stiffening steel pipe 110, and between the side edge portion of the main shaft member 151 and the corner portion of the stiffening steel pipe 110. A gap 120 having a size (for example, 1/15 of the plate thickness of the main shaft member 151) is secured. On the other hand, the auxiliary shaft member 152
Between the side edge portion S0 and the corner portion la of the stiffening steel pipe 120, and between the side edge portion N of the auxiliary shaft member 152 and the corner portion C of the stiffening steel pipe 110. 130 (for example,
The plate thickness of the main shaft member 151) is secured. Therefore, as in the case of FIG. 1A, a predetermined value is secured for the proof stress of the shaft member 150, and further, the shaft member 1 is placed in the stiffened steel pipe 110.
50 can be easily inserted, and the stiffening effect of the stiffening steel pipe 110 on the shaft 150 is increased. In particular, the auxiliary shaft material 15
Since 2 has a T-shaped cross section, the proof stress of the shaft member 150 itself is increased.

In FIG. 1 (f), reference numeral 160 denotes a shaft material, which is obtained by integrally molding the main shaft material 151 and the auxiliary shaft material 152 in FIG. 1 (e). The same parts as those in (e) of FIG. 1 are designated by the same reference numerals, and part of the description will be omitted. Therefore, also in (f) of FIG.
The same action and effect as in (e) of FIG. 1 can be obtained.

[Second Embodiment] FIG. 2 is a sectional view of a steel pipe stiffening brace material according to a second embodiment of the present invention. Figure 2
In the first embodiment (FIG. 1), the liner is inserted in the gap between the side edge portion of the main shaft material and the corner portion of the stiffening material. The same parts as those in the first embodiment (FIG. 1) are designated by the same reference numerals, and the description thereof is partially omitted.

FIG. 2A is the same as FIG. 1A.
The liner 210 is inserted into the gap 30. That is, the stiffening steel pipe 10 is elastically deformed into a flat shape, and the shaft member 20 and the liner are inserted into the stiffening steel pipe 10 in a state where the distance between the corner e and the corner g is enlarged (the gap 30 is enlarged). Two
10 can be easily inserted. Therefore, FIG.
The same action and effect as those in (a) can be obtained. Furthermore, since the side edges a and c of the main shaft member 21 are securely restrained to the corners e and g of the stiffening member 10 via the liner 210, a predetermined stiffening effect is guaranteed. Further, since the side edge portions a and c of the main shaft member 21 do not directly contact the corner portions e and g of the stiffening member 10, generation of friction noise due to sliding is prevented.

FIG. 2B is the same as FIG.
The liner 210 is inserted into the gap 30. Figure 2
(C) and (d) are obtained by inserting the liner 220 into the gap 80 in (c) and (d) of FIG. 1. 2 (e) and 2 (f) are obtained by inserting the liner 230 into the gap 120 in FIGS. 1 (e) and 1 (f). Therefore, (b), (c), and
(D), (e) and (f) have the same actions and effects as (b), (c), (d), (e) and (f) of FIG. 1, respectively. Further, as in the case of FIG. 2A, a predetermined stiffening effect is assured, and the generation of friction noise due to sliding is prevented.

[Third Embodiment] FIG. 3 shows a joining member installed at an end of a steel pipe stiffening brace material according to a third embodiment of the present invention. (A) is a partial side view and (b) is a sectional view. Is a sectional view. The same parts as those in Embodiment 1 ((a) of FIG. 1) are designated by the same reference numerals, and a part of the description will be omitted.
Further, the joining member is used to install the steel pipe stiffening brace material on a frame such as a pillar or a beam.For example, a bolt hole is bored and a bracket installed on the frame is installed by a bolt. It is something. In FIG. 3, the joining member 300 has a substantially cruciform cross section, and has a main joining portion 321 joined to the main shaft member 21 of the shaft member 20 and a sub joining portion 322 joined to the auxiliary shaft member 22. ing.

The width of the main joint portion 321 (the distance between the position “a” and the position “o” in the figure) is the same as the width of the main shaft member 21 (the distance between the position “a” and the position “c”), and the plate thickness of the main joint portion 321 is It is thicker than the plate thickness of the main shaft member 21 and is on the side edge of the main joint 321 (positions ヰ, 㽰).
Both corners are chamfered. The width of the sub-joint 322 (the distance between the position and the position in the figure) is not shown.
The distance between the opposite corners of 0 (the distance between the position F and the position C in FIG. 1) is the same, and the plate thickness of the sub-joint 322 is larger than the plate thickness of the sub-shaft member 22. Both corners of the edges (position no. K) are chamfered. Therefore, when the joining member 300 joined to the shaft member 20 is inserted into the stiffening steel pipe 10, a total of four side edge portions (positions ‘No’, ‘W’, and ‘K’) of the main joining portion 321 and the sub joining portion 322 are The four corners of the stiffening steel pipe 10 (not shown) (positions e, f, g, and d in FIG. 1) are faced to each other (abut directly or through a liner,
Or with a predetermined gap). Further, the proof stress of the joining member 300 is 1.2 times or more the proof stress of the shaft member 20. Therefore, even if the shaft member 20 yields, the joining member 300 is
It is possible to maintain elasticity and maintain the relative position with the stiffening tube.

When the joining member 300 is formed of a material having a higher strength (yield stress) than the shaft member 20, the plate thickness of the main joint portion 321 and the plate thickness of the main shaft member 21 are the same, and the sub joint portion 322 is the same. Even if the plate thickness of 1 and the plate thickness of the sub-shaft member 22 are the same, the proof stress of the joining member 300 can be 1.2 times or more the proof stress of the shaft member 20. Note that the third embodiment can be applied to the stiffening steel pipe and the shaft material having any of the shapes shown in the first and second embodiments.

[Embodiment 4] FIG. 4 is a schematic diagram showing the outline of a compression tension repeating experiment for calculating the cumulative plastic deformation capacity of a steel pipe stiffening brace material according to Embodiment 4 of the present invention. Stiffening steel pipe (square) is STKR400, □-
It uses 150x150x9. In FIG. 4, the shaft member 20 is inserted into the stiffening steel pipe 10, the joining member 300 is joined to the longitudinal end portion of the shaft member 20, and the joining member 3
The experimental mounting portions 400 and 500 are joined to 00. Then, the experimental attachment part 500 is attached to a compression tension repeating tester (not shown).

FIG. 5 is a sectional view of a shaft material of a steel pipe stiffening brace material according to a fourth embodiment of the present invention. The shaft material is a cross-shaped rolled steel of unequal sides, and low yield point steel with a yield point of 100 N / mm ² is used. Further, the inner dimension and plate thickness of the main shaft member are defined by B1 and t1 in the figure, and the inner dimension and plate thickness of the auxiliary shaft member are defined by B2 and t2 in the figure.

FIG. 6 is a load-displacement curve for calculating the cumulative plastic deformation capacity of the steel pipe stiffening brace material according to the fourth embodiment of the present invention. The load is ± 0.5 as the average strain of the shaft.
% And ± 1.0% were repeated twice, and the cumulative plastic deformation capacity was calculated until the load dropped 1.5% from the maximum load of 1.5%. The cumulative plastic deformation capacity is calculated by dividing the plastic absorbed energy by the product of yield strength and yield deformation as shown in FIG.

Table 1 shows the results of the experiments of the present invention and a comparative example (an example in which the side edge portion of the sub-shaft is also in contact with the stiffening steel pipe, and an example not including the sub-shaft (flat steel type shaft)). Indicates the calculated cumulative plastic deformation capacity. The inner dimension B1 of the main shaft member is set to abut on the opposite corner of the stiffened steel pipe, and the plate thickness t1 is changed. The inner dimension B2 of the sub-shaft is the inner dimension B of the main shaft.
The plate thickness t2 was changed to 1/2 of 1. Generally, the required cumulative plastic deformation capacity of the energy absorbing member required for one large earthquake is several hundred (200 to 400), so 100
If it exceeds 0, it can withstand several earthquakes and does not need to be replaced. From Table 1, the present invention 1 in which only the supporting shaft material is stiffened by the stiffening steel pipe shows almost the same cumulative plastic deformation magnification as Comparative Example 1 in which both the supporting shaft material and the sub-shaft material are stiffened. It is shown that the invention is easy to manufacture and has a certain seismic resistance. Further, it can be seen that the cumulative plastic deformation capability decreases as the width-thickness ratio (B1 / t1) of the main shaft material increases (the plate thickness decreases). If the width-thickness ratio of the main shaft material is about 6.5 and the width-thickness ratio (B2 / t2) of the auxiliary shaft material is 5.5 or less, the cumulative plastic deformation capacity exceeds 1000, and sufficient plastic deformation capacity is obtained. Show. Even if the width / thickness ratio of the main shaft material is about 7.5 and the width / thickness ratio of the auxiliary shaft material is about 5.5, it is possible to withstand one earthquake.

[0033]

[Table 1]

Although a square steel pipe has been described above as the stiffening steel pipe, the stiffening steel pipe of the present invention is not limited to this, and even if it is a circular steel pipe or an oval steel pipe, In order to achieve the action and effect of the present invention, a ridge or the like (for example, a bar material installed in parallel) that can restrain the side edge portion of the main shaft material is installed at the opposite position of It is included in the stiffening steel pipe of the invention.

[0035]

As described above, according to the present invention, a steel pipe stiffener that can be easily manufactured, guarantees the accuracy of the gap between the shaft member and the stiffening steel pipe, and has a predetermined proof strength and seismic resistance. Brace material is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a steel pipe stiffening brace material according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a steel pipe stiffening brace material according to a second embodiment of the present invention.

FIG. 3 shows a joining member installed at an end of a steel pipe stiffening brace material according to a third embodiment of the present invention. (A) is a partial side view and (b) is a sectional view.

FIG. 4 is a schematic diagram showing an outline of a repeated compression-tension experiment for selecting the cumulative plastic deformation capacity of the steel pipe stiffening brace material according to the fourth embodiment of the present invention.

FIG. 5 is a sectional view of a shaft member of a steel pipe stiffening brace member according to a fourth embodiment of the present invention.

FIG. 6 is a load-displacement curve for calculating the cumulative plastic deformation capacity of the steel pipe stiffening brace material according to the fourth embodiment of the present invention.

[Explanation of symbols]

10 Stiffened steel pipe with a substantially square cross section 20 Shaft with joint structure 21 Main shaft material that constitutes the shaft material 20 22 Sub-shaft material constituting the shaft material 20 23 Main shaft member 21 and auxiliary shaft member 22 are joined 30 Gap between side edge of main shaft and stiffening steel pipe 40 Gap between side edge of sub-shaft and stiffening steel pipe 50 integrally molded shaft 210 liner 220 liner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromi Shimokawa             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. F term (reference) 2E125 AA33 AA48 AB16 AB17 AC16                       AG03 AG12 AG57 BB01 BB08                       BB22 BE08 BF04 BF08 CA05

Claims (10)

[Claims] 1. A steel pipe stiffening brace member comprising a stiffening steel pipe made of a rectangular steel pipe and a shaft member penetrating the stiffening steel pipe to bear an axial force, wherein the shaft member has both side edge portions. Has a plate-shaped main shaft member facing the opposite corners of the stiffening steel pipe, and a sub-shaft member installed on the side surface of the main shaft member through a gap with the inner surface of the stiffening steel pipe. Steel pipe stiffening brace material. 2. The steel pipe stiffening brace material according to claim 1, wherein the entire length or a part of both side edge portions of the main shaft member abut on the opposite corner portions of the stiffening steel pipe. 3. The both side edges of the main shaft member are arranged at opposite corners of the stiffening steel pipe with a gap, and a liner plate is inserted into the gap.
Steel pipe stiffening brace material described. 4. The steel pipe stiffening brace material according to claim 1, wherein the shaft member has a cross-shaped cross section or a T-shaped cross section. 5. The cross section of the shaft member is of a scalene cross shape, the inner dimension of the main shaft member is 6.5 times or less the plate thickness of the main shaft member, and the inner dimension of the auxiliary shaft member is the above. Sub-shaft material thickness 5.5
The steel pipe stiffening brace material according to any one of claims 1 to 3, wherein the brace material is not more than double. 6. The cross section of the shaft member is a scalene cross, and the cross sectional area of the main shaft member is 1.5 times the cross sectional area of the sub shaft member.
The steel pipe stiffening brace material according to any one of claims 1 to 3, wherein the stiffening brace material is double or more. 7. The cross-sectional area of the main shaft member is 45% or less of the total cross-sectional area of the shaft member, and the stress increase rate of the steel material forming the main shaft member is 1.3 or more. The steel pipe stiffening brace material according to any one of claims 1 to 5. 8. The proof stress of the joining member installed at the longitudinal end portion of the shaft member is 1.2 times or more the proof stress of the longitudinal central portion of the shaft member. 7. A steel pipe stiffening brace material according to any one of 7. 9. The joining member installed at the longitudinal end portion of the shaft member has a substantially cruciform cross-sectional shape, and the side edge portion of the joining member directly or at a corner of the stiffening steel pipe. The abutting member is abutted via a liner plate.
The steel pipe stiffening brace material according to any one of 1. 10. The steel pipe stiffening brace material according to claim 1, wherein the steel material forming the main shaft material is made of low yield point steel.