JPH08165744A - Reinforcing structure of structural member - Google Patents

Abstract

PURPOSE: To prevent the generation of abrupt collapse or lateral buckling, increase plastic deformability, and make effective use of a space wherein a reinforced part is utilized as a duct or the like in a structural member which comprises an H-cross section member. CONSTITUTION: As a reinforcing material, halves of a steel pipe 55 is welded at the central part of both surfaces of a web 4 of an H-section 1 as an H- sectional beam, thereby forming an enclosed cross section area. The steel pipe 55 is mounted on an neutral axis of the H-section 1 in the longitudinal direction, and the steel pipe 55 bars almost no load under a normal load state. As a bearing fore reduces in the structural member on a compression side produced by the buckling of a compression side flange, the central axis of the entire beam is deviated to a tensile side so that the steel pipe 55 comes to share the load for the deterioration in the bearing forth as a reinforcing member, thereby preventing an abupt drop of a load resistant capacity. The reinforcement of the enclosed cross section increases greatly the torsional rigidity of the member, and the structure is effective to resist against lateral buckling as well. It is further possible to use the internal part of the reinforced part of this enclosed cross section for wiring or an air conditioning duct.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an H-shaped cross-section member such as an H-section steel as a structural member mainly used for a beam or a column in which bending is dominant (in the case of a beam, H is actually in a horizontal direction). Although an I-shaped cross section is common, for convenience of description, it will be referred to as an H-shaped cross-section member including them. The same applies in the following description) for preventing deterioration of load bearing capacity due to buckling of the compression side flange. The present invention relates to a reinforced structure of a reinforced structural member.

[0002]

2. Description of the Related Art In structural members such as H-shaped cross-section beams, there is a problem that the load bearing capacity of the members is sharply reduced due to buckling of the compression side flange. To solve this problem, stiffeners or reinforcing ribs should be provided at the parts that receive large bending moments to stiffen them, or reinforcing ribs etc. should be provided to increase the rigidity when there is a risk of buckling as a member. It is generally done.

In general, a beam has a lower rigidity in the lateral direction than the rigidity around the main axis that receives bending, and there is a risk of lateral buckling (sideways buckling). Therefore, in the design, the main beam is constrained by a connecting beam or the like orthogonal to the main beam so as not to fall over.

Further, in the case of seismic design, if it is necessary to maintain the plasticity of the members and the subsequent deformability, lateral buckling stoppers such as joint beams are arranged quite densely so that the beams do not buckle laterally and the strength does not deteriorate. Must.

The connecting beam and the fired material at the end of the material thus arranged make the frame extremely complicated and pose many design problems.

On the other hand, Japanese Patent Laid-Open No. 59-61645 discloses a groove-shaped groove between upper and lower flanges of an H-shaped cross-section member, etc., for the purpose of improving the bending resistance of a beam, only in a portion requiring a large bending rigidity. A cross-member is fitted and bolted together, or a mountain-shaped cross-member is joined to the corners of the flange and the web to increase the strength of the structural member without increasing the external dimensions of the structural member. Is disclosed.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention JP-A-59-6164
In addition to the invention described in Japanese Patent No. 5 publication, the conventional concept of reinforcement for structural members is to improve the bending resistance of structural members such as beams, and buckling stiffening by reinforcing ribs is also performed. The strength is improved by providing reinforcing ribs at required intervals and shortening the buckling length.

However, in the conventional buckling stiffening, once the buckling occurs due to the large deformation, the proof stress as the structural member may be rapidly deteriorated and the structural strength may not be established.
It is not based on the idea of stably deforming structural members and positively utilizing their plastic deformation ability.

For example, in the case of an H-shaped steel beam, in the region where the plasticization progresses, the rigidity of the compression side flange is remarkably reduced, and the local buckling deformation of the compression flange increases, and
It spreads to the web, causing bending and torsional deformation as a whole beam, causing lateral buckling failure. Therefore, in the region where the beam becomes plastic, the web is soundened by the stiffening member abutting on the web, and the stiffening member maintains elasticity, so that the stiffening member, which is not so large, has a beam main body. Sufficient rigidity can be expected to prevent lateral buckling, and stable deformation performance can be ensured while compensating for deterioration of proof stress due to local buckling deformation of the flange.

The present invention solves the above-mentioned problems in the prior art, and prevents a structural member consisting of an H-shaped cross-section member from abruptly collapsing or lateral buckling due to local buckling of the compression side flange, and has a plastic deformability. It is an object of the present invention to provide a reinforcing structure which is high in cost and can effectively utilize the space by using the reinforcing portion as a duct or the like.

[0011]

According to the present invention, an H-shaped cross-section member as a structural member having flanges at both ends of a web has a predetermined torsional rigidity extending in the neutral axis direction at or near the neutral axis of the member cross section. The hollow tubular reinforcing portion is provided so that the hollow tubular reinforcing portion gradually takes up part of the stress generated in the vicinity of the neutral axis as the deformation of the compression side flange progresses.

As the compression side flange is deformed and the proof stress is reduced, the substantial neutral axis of the H-shaped cross-section member shifts to the tension side, and the proof portion is sequentially responsible for the deterioration of the proof stress, so that the compression side flange buckles. It is possible to make up for the decrease in proof stress due to.

The hollow tubular reinforcing portion may be provided over the entire length of the H-shaped cross-section member, or may be partially provided only in the vicinity of the region where the compression side flange may cause buckling.

As the form of the reinforcing portion, a half steel pipe member having a predetermined torsional rigidity as a reinforcing member is attached to both sides or one side of the web of the H-shaped cross-section member, and the hollow tubular reinforcing portion has an H-shaped cross section. Several cases are conceivable, such as one formed integrally with a member, one in which a T-shaped steel web tip is welded to the upper and lower sides of a steel pipe member as a reinforcing portion to form an H-shaped cross-section member.

In addition to the reinforcing effect on the buckling of the compression side flange, the reinforcing portion in the present invention has a closed cross section in the vicinity of the neutral axis of the H section steel structural member having an open cross section with relatively small torsional rigidity. By forming the portion, the torsional rigidity can be significantly improved, and the effect of preventing lateral buckling is great.

Further, a hollow tubular reinforcing portion formed of a half-divided steel pipe or a steel pipe member forming a closed cross section is also used as a duct for piping or wiring, or a connection port for the duct is provided at a predetermined position. It is possible to make effective use of space.

[0017]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In this embodiment, a web 4 of H-section steel 1 as an H-section beam is used.
A half-divided steel pipe 55 is welded to the central portion of both surfaces as a reinforcing member, and a closed cross-section portion is formed in a part of the cross-section of the open cross-section member which is weak against torsion.

The half-divided steel pipes 55 are mounted on both sides of the web 4 on the neutral axis of the H-shaped steel 1 along the longitudinal direction thereof, and under normal load conditions, the steel pipes 55 bear almost no load.

As the yield strength on the compression side of the structural member due to buckling of the compression side flange decreases, the neutral axis of the entire beam shifts to the tension side, and the deterioration of the yield strength is sequentially shared by the steel pipe 55 as a reinforcing member.

This prevents a sudden drop in load bearing capacity due to buckling of the compression side flanges of the upper and lower flanges 2, 3. Also, in addition to the effect of reinforcing the local buckling of the flange at the end of the material, etc., the torsional rigidity of the member is significantly increased.
It is also effective for lateral buckling.

In this embodiment, the end of the steel pipe 55 is the pillar 1.
0, and the stress in the longitudinal direction of the steel pipe 55 that increases due to the buckling deformation of the lower flange 3 at the beam end (or the buckling deformation of the upper flange 2 at the beam longitudinal center) is directly transmitted to the column 10. Has become.

FIG. 2 is an analytical model diagram relating to an increase in torsional rigidity when the half steel pipe 55 corresponding to the embodiment of FIG. 1 is used.

FIG. 2 (a) shows an H-section steel set in the model, which was calculated with h / b = 3, b / t _f = 10 and t _f / t _w = 2 (where b is the flange width). , H is the height, t _w
Is the web thickness and t _f is the flange thickness). Figure 2 (b) shows
When a reinforcing member that satisfies the conditions of d / b = 1 and d / t _d = 10 is used as Case 1, (where d is the outer diameter of the half-divided tubular body and t _d is the thickness of the thin tubular body). ). Figure 2
Similarly, in case (c), as Case 2, d / b = 1.2, d / b
This is the case where a reinforcing member that satisfies the condition of t _d = 10 is used. All materials are the same.

When calculated under the above conditions, the torsion constants of the respective cross sections in case 1 and case 2 are about 50 times and about 100 times that in the case without the reinforcing member. Further, since the elastic lateral buckling load of a beam with a large span is proportional to the square root of the approximate torsional rigidity, it is about 7 times and about 10 times in case 1 and case 2, respectively, compared to the I-shaped section before reinforcement.

FIG. 3 shows a half-split steel pipe 55 as a reinforcing member.
FIG. 4 shows the test body and the test method used in the experiment for confirming the effect of, and the test results.

This experiment is a beam bending experiment, and the test body has a height of 300 mm, a flange width of 100 mm, a web thickness of 6 mm, a flange thickness of 10 mm, a length of 3,000 mm, and a yield point of the member σ _y = 40.5 kg / mm. ² H-section steel was used. With respect to the cross-section neutral axis of the H-section steel 1, a half-divided steel pipe 55 having a diameter of 89.1 mm and a thickness of 3.2 mm is provided as a reinforcing member on both sides of the web 4.
Was welded horizontally. A bending moment M is applied to both ends of this test body to deform the upper and lower flanges 2 and 3 in the lateral direction u ₁ ,
I asked for u ₂ .

In the graph of FIG. 4, the vertical axis represents the bending moment M by the total plastic moment M _p , and the horizontal axis represents the lateral deformation u divided by the flange width b.

The solid lines indicated by A ₁ and A _{2 represent} the relationship between the bending moment and the lateral deformation of the upper and lower flanges 2 and 3 due to lateral buckling when the reinforcement of the present invention is applied, and B ₁ and
The broken line indicated by B ₂ is the relationship between the bending moment when there is no reinforcement and the lateral deformation of the upper and lower flanges 2 and 3 due to lateral buckling.

By reinforcing the steel plate 55 from both sides with half-split steel pipes, the torsional rigidity becomes 25 times stronger than the original cross section. As shown in the figure, in the case of no reinforcement, it is about 0.5 times the plastic moment. The elastic buckling did not buckle laterally until near the plastic moment. Further, in the unreinforced beam having a small torsional rigidity, the deformation in the lateral direction occurred from the initial stage of the applied force, whereas in the reinforced beam of the present invention, the lateral swing did not occur near the maximum load,
It is extremely stable. From the lateral deformation of the upper flange 2 and the lower flange 3, it can be seen that the reinforced beam is less likely to be twisted than the unreinforced beam.

5 to 7 show another embodiment in which the inside of the reinforcing member 65 having a groove-shaped cross section forming a closed cross section can be used also as a duct for air conditioning or the like. is there. 6 is a GG cross section of FIG. 5, and FIG. 7 is HH of FIG.
Corresponds to the cross section.

The reinforcing member 65 is preferably attached to the entire length of the H-section steel 1 or a considerable part thereof. In this embodiment, the reinforcing member 65 is fixed to the web 4 of the H-section steel 1 by the bolt 66. In the figure, 67 is a through hole provided in the H-shaped steel 1, and 68 is a connection port for a duct provided in the reinforcing member 65.

8 and 9 correspond to a modification of the embodiment of FIG. In the embodiment of FIG. 1, an H-section steel 1 and a half-split steel pipe 5 are used.
5 was welded, in the embodiment of FIG. 8, a round steel tubular portion 75 as a reinforcing portion and a T-shaped portion 72 provided above and below,
By integrally molding the substantially H-shaped structural member 71 together with 73, the cross section is further rationalized. Functionally, it is substantially the same as in the case of FIG. 1, and a similar shape can be obtained by welding the web ends of the T-shaped steel to the upper and lower portions of the round steel pipe.

In the embodiment shown in FIG. 8, the cross section of the reinforcing portion is circular, whereas in the embodiment shown in FIG. 9, the reinforcing portion has a shape close to a square (square steel tubular portion 75 ').

FIGS. 10 to 12 show an embodiment in which the reinforcing portion can also be used as a duct for air conditioning, as in the embodiment of FIGS. 5 to 7, and the structural members are shown in FIG. It corresponds to the structural member 71 including the round steel tubular portion 75 and the T-shaped portions 72 and 73. 11 is a cross section taken along line I-I of FIG. 10, and FIG. 12 is shown in FIG.
In the figure, 76 is a reinforcing rib provided at a predetermined interval, and 77 is a connection port provided in a direction perpendicular to the round steel tubular portion 75 as a reinforcing portion.

[0036]

EFFECTS OF THE INVENTION With respect to the local buckling of the compression side flange in the H-shaped cross-section member, the hollow tubular reinforcing portion provided at or near the neutral shaft bears the reduced load-carrying capacity, and the structural member as a whole collapses. It can be effectively prevented.

Since the reinforcing portion is provided on the neutral axis of the structural member or in the vicinity thereof, it hardly contributes to the initial stress-deformed state and does not complicate the design.

When it is applied to the member end portion of the H-shaped cross-section member, it is possible to compensate for the decrease in load bearing capacity due to buckling of the compression side flange and to exhibit the plastic deformation ability at the member end portion.

By forming the reinforcing portion forming the closed cross section in the vicinity of the neutral axis of the H-shaped cross section member which is the open cross section member,
In addition to the above effects, the torsional rigidity can be increased,
A lateral buckling prevention effect can also be obtained.

It is also possible to use the space effectively by using the closed cross section formed by the reinforcing portion also as the duct.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment in which the present invention is applied to an H-shaped cross-section beam.

2 (a) to (c) are analytical model diagrams relating to an increase in torsional rigidity when a half steel pipe is used as a reinforcing member.

FIG. 3 (a) is a front view showing a test body used in an experiment,
(b) is the side view.

FIG. 4 is a graph showing test results for the test body of FIG.

FIG. 5 is a front view showing another embodiment of the present invention.

6 is a sectional view taken along line GG of FIG.

7 is a sectional view taken along line HH of FIG.

FIG. 8 is a side view of a structural member showing an embodiment in the case of integral molding as a modification of the embodiment of FIG.

FIG. 9 is a side view of a structural member showing another embodiment in the case of integral molding.

FIG. 10 is a front view showing an embodiment in which a reinforcing portion is also used as a duct.

11 is a cross-sectional view taken along the line I-I of FIG.

12 is a sectional view taken along line JJ of FIG.

[Description of sign]

1 ... H-section steel, 2 ... upper flange, 3 ... lower flange, 4 ... web, 10 ... column, 55 ... half steel pipe, 65 ... reinforcing member,
66 ... Bolt, 67 ... Through hole, 68 ... Duct connection port,
71 ... Structural member, 72, 73 ... T-shaped part, 75 ... Round steel tubular part, 75 '... Square steel tubular part 75'

Claims (8)

[Claims] 1. A hollow tubular reinforcing portion extending in the direction of the neutral axis and having a predetermined torsional rigidity is provided at or near the neutral axis of the member cross section of the H-shaped cross-section member as a structural member having flanges at both ends of the web. A reinforcing structure for a structural member, wherein a part of stress generated in the vicinity of the neutral axis as the deformation of the compression side flange progresses is gradually taken up by the reinforcing portion. 2. The reinforcing structure for a structural member according to claim 1, wherein the reinforcing portion is partially provided only in the vicinity of a region where the compression side flange may cause buckling. 3. The reinforcing portion is provided at or near a neutral axis of a member cross section of the H-shaped cross-section member, in parallel or substantially parallel to the neutral axis, over the entire length of the H-shaped cross-section member. Reinforcement structure of structural members. 4. The reinforcing structure for a structural member according to claim 3, wherein the reinforcing portion also serves as a pipe or a duct for wiring. 5. The reinforcing structure for a structural member according to claim 4, wherein a connection port for a duct is provided at a predetermined position of the reinforcing portion. 6. The reinforcing member is made of a half-divided steel pipe member having a predetermined torsional rigidity as a reinforcing member, and is attached to both sides or one side of the web.
The reinforcing structure for the structural member according to 3, 4, or 5. 7. The reinforcing structure for a structural member according to claim 1, wherein the reinforcing portion is integrally formed with the H-shaped cross-section member. 8. The H-shaped cross-section member as a structural member,
The reinforcing structure for a structural member according to claim 1, 2, 3, 4 or 5, wherein the tip ends of a T-shaped steel web are welded to the upper and lower sides of a steel pipe member serving as a reinforcing portion.