JPH0849349A - Structure for reinforcing steel structural member - Google Patents

Abstract

PURPOSE:To provide a reinforcing structure which is manufactured at a low cost and excellent in workability and widely selectable in terms of design by giving consideration to the plasticity of a steel structural member and using cast-in-place concrete or precast concrete blocks as a reinforcing material CONSTITUTION:A precast concrete member 11a, which serves as a concrete block, is manufactured so as to reinforce the ends of an H section-made beam 2 where the shape of the concrete member 11a is so designed that it may be splice-welded with the H section in an area enveloped by upper and lower flanges 2a and a web 2b. The precast concrete member 11a is splice-welded from both sides so as to clamp the web 2b and fixed with bolts 14. Although this construction serves to restrict local deformation of the flanges 2b with the precast concrete member 11a, it is still necessary to suppress the generation of deformation to a satisfactory extent in order to ensure the toughness of the beam 2. Generally, the precast concrete member 11a is fixed with the web 2a, but it is not fixed with the flanges 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel frame structural member having flanges at both ends of a web, such as an H-shaped steel mainly used for a beam or a column in which bending is dominant, and plasticizes a cross section of the structural member due to an earthquake load or the like. The present invention relates to a stiffening structure in consideration of.

[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. An example of such a conventional reinforcing mode is shown in Japanese Utility Model Laid-Open No. 52-69112.

Further, in Japanese Patent Laid-Open No. 59-61645, for the purpose of improving the bending resistance of a beam, only a portion requiring a large bending rigidity is provided with a groove shape between upper and lower flanges of an H-shaped cross-section member or the like. 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.

[0004]

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 it may not be structurally established.
It is not based on the idea of stably deforming structural members and positively utilizing their plastic deformation ability.

On the other hand, the applicant previously attached a stiffening member to the web of the steel structural member made of H-section steel or the like to suppress the local deformation and plate buckling of the web, and the flange or the flange and the web. Various plastic deformations are allowed, and the plastic deformation ability as a structural member is positively utilized to develop various structures for utilizing in the design (Japanese Patent Laid-Open No. 5-33196).
No. 3, JP-A-5-331964, JP-A-6-
No. 17507, Japanese Patent Laid-Open No. 4-809767,
See Japanese Patent Publication No. 4-814007, etc.).

The present invention relates to a stiffening structure that takes into account the plasticization of the cross-section of the structural members that have been previously developed. By using a cast-in-place or precast concrete block as the stiffening member, the material cost can be reduced and construction can be performed. Simplification,
This is to expand the range of choices in design.

[0008]

The stiffening structure of the present invention comprises:
For steel frame structural members such as beams or columns that have flanges on both ends of the web, inside the web and the flange,
Place the concrete block so that it is in contact with the web at the surface, press the web from both sides with the concrete block to restrain the deformation of the web, while allowing plastic deformation of the flange due to the load acting on the steel structural member, as a steel structural member The plastic deformation ability of the steel is utilized in the design, that is, the toughness of the steel frame structural member is enhanced.

The concrete block referred to in the present application is not limited to a precast concrete block, but includes a concrete block directly cast into a steel structure member at a factory or on site and formed into a block shape by hardening.

According to the stiffening structure of the second aspect, the concrete block is brought into contact with the web surface and also with the inner surface of the flange. That is, the concrete block as the stiffening member prevents the local deformation of the web, and the toughness of the steel structural member is ensured while the buckling deformation of the compression side flange is restrained to some extent.

In this case, the fixing of the concrete is basically performed on the web and is not integrated with the flange.
The reason is that it is effective to secure toughness that the occurrence of local deformation of the flange is not completely stopped. As a concrete fixing means, a shear connector such as a stud may be fixed to the web when the concrete is cast in situ, or a bolt that penetrates the concrete and the web may be used in the case of precasting.

In addition, if there is a stiffener between the fan radiators, it is possible to fix the concrete to the stiffener, but in this case as well, in principle, it is desirable that the concrete and the flange are not integrated.

However, it is possible that the concrete block is partially fixed to the flange while allowing local deformation of the flange to some extent.

That is, in the stiffening structure according to claim 3, the concrete block and the flange are fixed at predetermined intervals in the longitudinal direction of the steel structural member with a shear connector or the like, and the interval is set, whereby the flange buckles. The length is adjusted, and the toughness can be secured by the controlled local deformation of the flange.

According to a fourth aspect of the stiffening structure, the inner surfaces of the concrete block and the flange are wholly or partially separated from each other.

In this case, the local deformation of the flange is considerably allowed, and the web in the vicinity of the flange is also partially allowed to be deformed. In addition, since the stiffening member consisting of a concrete block is located near the neutral axis of the steel structural member, it is possible to compensate for the deterioration of the bending strength of the compression side flange due to plasticization in the concrete block part, and the It is possible to prevent a decrease in yield strength and effectively utilize the plastic deformation capacity of the steel structural member.

As a form of the concrete block for the web of the steel structural member, a predetermined section including a section in which plasticization due to bending and torsional deformation of the flange is considered is provided in the vicinity of the neutral axis of the steel structural member in parallel with the flange. Thing, in addition to the parallel part provided in parallel with the flange, connect both flanges (including the case where there is a gap with the flange)
An H shape having a vertical portion, an X shape extending between both flanges (including a case where there is a gap with the flange), and the like are considered.

The stiffening structure according to claim 5 is a case where the concrete block is a precast concrete block, and as described above, the concrete block in the present application is formed by directly placing it on a steel structural member at a factory or on site. Some will be installed later and some will be installed later in the form of precast concrete blocks.

According to a sixth aspect of the stiffening structure, the concrete block is attached to the stiffener when the steel structural member has a stiffener for connecting the flanges. In this case, it may be fixed only to the stiffener, to both the stiffener and the web, or in some cases also to a part of the flange.

Fixing to the stiffener can be performed by using a metal fitting such as a bolt in the case of a precast concrete block, or by attaching a shear connector to the stiffener in the case of cast-in-place concrete.

According to a seventh aspect of the stiffening structure, a reinforcing steel material is arranged in the concrete block in parallel with the flange of the steel frame structural member.

When the yield strength of the steel structural member is deteriorated due to the occurrence of local buckling of the compression side flange, the deterioration can be compensated by the reinforcing steel material such as the reinforcing bar arranged in the concrete.

The reinforcing steel members are arranged in parallel with the flanges of the steel structural member, or arranged in an X shape near the corners of the flange and the stiffener, and a truss member structure is used to compensate for the deterioration of yield strength. Things etc. are considered.

In the stiffening structure according to claim 8, when an opening is provided in the web of the steel structural member, a concrete block is provided inside the area surrounded by the web and the flange for a predetermined section sandwiching the opening. It is arranged to restrain the deformation of the web around the opening.

The stiffening structure according to claim 9 uses, as the concrete block, a precast concrete block having an opening formed in advance at a position corresponding to the opening of the steel structure member. Since the part can be used for positioning, on-site construction becomes very easy.

[0026]

FIG. 1 shows an embodiment of the present invention, in which a web 2a is provided in a portion surrounded by a flange 2b and a stiffener 3 over a certain length in the vicinity of a column joint of an H-shaped steel beam 2. Concrete 11 is placed so as to sandwich.

As a result, local deformation of the thin web 2a can be prevented, and buckling deformation of the compression side flange can be restrained, so that the toughness of the steel frame member can be secured.

The fixing of the concrete 11 is maintained by the studs 12 and the like which are welded to the web 2a, and is not integrated with the flange 2b in principle. This is because it is effective to secure the toughness if the occurrence of local deformation of the flange 2b is not completely stopped.

FIG. 2 shows another embodiment of the present invention. Concrete 11 cast from both sides of the web 2a.
The reinforcing bars 13 are arranged and reinforced inside.

Particularly, when local buckling of the compression side flange and accompanying proof strength deterioration of the beam 2 are expected, a reinforcing steel material such as a reinforcing bar 13 is passed through the middle part of the concrete 11 as an intermediate material to compensate for the deterioration. be able to.

That is, the bending moment M shown in FIG.
No. 3 hardly bears the bending moment, but as the local buckling of the compression side flange progresses, the load bearing capacity of the compression side flange deteriorates, and the bending moment m corresponding to the reduced load bearing capacity is borne by the reinforcing bar 13 and the tension side flange.

The reinforcing steel material such as the reinforcing bar 13 is arranged in parallel with the flange 2b as in the present embodiment, or is arranged in an X shape near the corners of the flange 2b and the stiffener 3 to form a truss member structure. It is also possible to consider a method of using this to compensate for the deterioration of yield strength.

FIG. 3 shows still another embodiment of the present invention, in which concrete 11 is placed between both flanges 1b of the H-shaped steel column 1 so as to sandwich the web 1a. In Fig. 3 (a), the studs are not provided on the flange 1b, whereas in Fig. 3 (b), the studs 12 are welded to the flange 1b and the concrete 11 is fixed at intervals of the studs 12.

The plastic deformation of the structural members is, of course, caused by the expansion and contraction in the plastic region, but rather, most of them are the deformation due to the local buckling in the plastic region in the case of the steel frame member and the cracks in the concrete member. Deformation due to crushing is dominant.

Therefore, in order to secure the toughness of the member, it is more effective in terms of performance to allow local deformation to some extent than to prevent local deformation of the web and the flange.

In general, since the local deformation of the web is suppressed by the concrete and the local deformation toward the inside of the flange is prevented, the flange and the concrete are not fixed to each other in principle.

However, when the width of the flange is large and the plate thickness is thin, or in the case of high-strength steel or the like, the yield strength of the member is greatly deteriorated due to local buckling. Therefore, in the embodiment shown in FIG. 3 (b), the concrete 11 and the flange 1b are intermittently fixed by the stud 12.

The above-described embodiments shown in FIGS. 1 to 3 are cases where the concrete 11 is cast-in-place concrete (including the case where it is cast in a factory), and the steel members directly constituting the beam 2 or the pillar 1 are used. The block is formed by being cast.

In the embodiment shown in FIG. 4, in advance, the region surrounded by the upper and lower flanges 2b and the web 2a can be attached.
A precast concrete member 11a is manufactured as a concrete block, and bolts 14 are provided so as to sandwich the web 2a.
It is fastened from both sides with etc.

Although the local deformation of the flange 2b is restrained, it is necessary to prevent the deformation completely in order to secure the toughness of the member, and it is a principle that the deformation is not stopped with the flange 2b. Flange 2b as in the example
When the width of the flange is large and the proof stress deterioration due to the local deformation is large, partial fastening with the flange 2b may be effective in order to suppress the local deformation of the flange 2b to some extent.

In the embodiment shown in FIG. 5, in order to secure a large plastic deformation of the main material, local deformation of the compression side flange is not directly suppressed, but the yield strength deterioration due to the stiffening of the web 2a and the local deformation of the compression side flange is compensated. This is the case where the H-shaped precast concrete member 11b for the purpose is used.

In this embodiment, the precast concrete member 11b is fixed to the stiffeners 3 on both sides with the bolts 14, but it may be fixed to the main material web 2a. Rebar arrangement in the precast concrete member 11b is performed as necessary.

As described above, the stiffening intervals of the cases of FIGS. 1 to 5 are slightly different depending on the stiffening / reinforcing method, but since the purpose is to increase the deformability associated with plasticization of the material end, It is a guideline for the expected length of plasticization.

If the stiffening section is too short or if the strength of the stiffening portion is too high, it is possible to cause local buckling away from the stiffening portion and lose the effect altogether.

FIG. 6 shows an embodiment of a stiffening structure using a precast concrete member 11c for reinforcement and stiffening near the opening 4 of the opening beam 2 made of H-shaped steel.

This precast concrete member 11c
Is a concrete in which an opening 15 having the same cross-sectional shape as the opening 4 of the beam 2 is previously formed and a stiffener 3c having an L-shaped cross section on both sides are integrated by studs 12c. It restrains the local deformation of 2a and compensates for the decrease in strength of the main material.

In the figure, the stiffeners 3c at both ends are attached to the bolt 1
It is fixed to the web 2a of the beam 2 at 4, but the flange 2
It may be fixed to b.

Reinforcing bars are arranged in the concrete around the opening 15 of the precast concrete member 11c, if necessary, but the arrangement is free.

FIG. 7 shows, as still another embodiment, an example of reinforcement of the continuous openings of the beam 2 for stiffening the openings 4a and 4b provided in the beam 2 in close proximity to each other. As the concrete block, a precast concrete member 11d provided with openings 15a and 15b having the same sectional shape as the openings 4a and 4b is used.

In the figure, this precast concrete member 11d is fixed to the stiffener 3 with bolts 14.

FIG. 8 shows an embodiment in which a normal precast concrete member 11e for stiffening and a precast concrete member 11f for opening reinforcement are used together.

The figure shows an example in which precast concrete members 11e are abutted from both sides of the web 2a over the entire length of the beam 2, and a precast concrete member 11f for opening stiffening having an opening 15c is provided around the opening 4c.

It is effective to manufacture and attach precast concrete members in a certain length unit so that they can be replaced if necessary.

FIG. 9 shows an example of the method of constructing the stiffening structure of the present invention for the H-shaped steel column 1. The figure is
It shows a state in which concrete 11 is placed in a column-beam joint and a portion surrounded by the flange 1b and the web 1a in the vicinity.

The concrete 11 is placed by the pillar 1 in front of the erection.
Is carried out from one side of the web 1a, and after curing, the column 1 is half-turned, and the casting is performed from the other side of the web 1a.

The purpose of placing concrete 11 is to use pillar 1
The first is to suppress the local deformation of the web 1a and restrain the buckling deformation of both flanges 1b.

It is also expected that the compressive force and the proof stress of the column subjected to shear bending can be increased by the combined effect of concrete and steel frame.

Further, by arranging the axial main bars 16 in the concrete 11, the strength of the H-shaped steel weak axis as the steel column 1 is increased, and the strength and rigidity in each direction of the strong axis and the weak axis are controlled. You can also

In addition, concrete 1 is also used in the beam-column joint.
1'can be placed to reinforce the steel panel zone, but this can be omitted.

FIG. 10 shows still another embodiment. Mainly, a precast concrete member 11g is abutted from both sides so as to sandwich the web 1a in an area where the end of the column 1 is present, and the web at the end of the column 1 is joined. The toughness of the column 1 is ensured by restraining local deformation of the flange 1a and the flange 1b.

In order to follow the bending shear deformation of the column, it is effective to form a block in layers in this way. In the example of the figure, the precast concrete members 11g arranged in multiple layers are fastened with long bolts 17.

[0062]

According to the present invention, a concrete block is arranged inside a web and a flange of a steel structure member so as to be in contact with the web at a surface, and the flange is restrained while the deformation of the web is restrained by the concrete block. It is possible to allow local deformation of the steel sheet to some extent to enhance the toughness of the steel structure member.

The force of plastic deformation of the steel structural member can be sufficiently exerted only by simply attaching the stiffening member.
It is easy to apply the existing structure to steel members.

In the present invention, since the cast-in-place or precast concrete block is used as the stiffening member, it is possible to reduce the material cost, simplify the construction, and expand the range of design choices.

In principle, the concrete block and the flange are not fastened, but the concrete block and the flange are fastened at predetermined intervals in the longitudinal direction of the steel structure member via a shear connector, etc. Adjust the buckling length of the flange by setting,
The toughness can also be ensured by the controlled local deformation of the flange.

When the concrete block as the stiffening member and the inner surface of the flange are separated from each other in whole or in part,
Local deformation of the flange is considerably tolerated, and the web near the flange is also partially deformed. In addition, since the stiffening member made of concrete block is located near the neutral axis of the steel structure member, the bending resistance deterioration of the compression side flange due to plasticization is compensated for by the concrete block part, and a sudden decrease in strength as a structural member. It is also possible to prevent and effectively utilize the plastic deformation ability of the steel structural member.

When the steel structural member has an opening, the concrete block as the stiffening member restrains the local deformation of the web or the web and the flange in the vicinity of the opening, thereby locally deforming between the flange and the web. Is suppressed. Further, even in a portion where a large bending moment occurs, deformation such as local plate buckling of the flange is suppressed, so that a rapid decrease in bending proof strength of the steel structural member is suppressed, and plastic deformation performance can be incorporated into the design.

[Brief description of drawings]

FIG. 1 is a perspective view of a beam end stiffening portion showing an embodiment of the present invention.

FIG. 2 is a perspective view of a beam end stiffening portion showing another embodiment of the present invention.

FIG. 3 is a perspective view showing an application example to a pillar member as still another embodiment of the present invention.

FIG. 4 is a perspective view of a beam end stiffening portion showing still another embodiment of the present invention.

FIG. 5 is a perspective view of a beam end stiffening portion showing still another embodiment of the present invention.

FIG. 6 is a perspective view showing an example of stiffening around an opening as still another embodiment of the present invention.

FIG. 7 is a perspective view showing an example of stiffening around a continuous opening as still another embodiment of the present invention.

FIG. 8 is a perspective view showing another embodiment of the present invention in which an ordinary stiffening and opening stiffening precast concrete member is used in combination.

FIG. 9 is a perspective view showing an example of a method for constructing a stiffening structure of the present invention.

FIG. 10 is a perspective view showing still another embodiment of the present invention, in which concrete blocks are arranged in layers at the ends of columns.

[Explanation of symbols]

1 ... Pillar, 1a ... Web, 1b ... Flange, 2 ... Beam, 2a
... web, 2b ... flange, 3,3c ... stiffener,
4, 4a, 4b, 4c ... Opening part, 11, 11 '... Concrete, 11a, 11b, 11c, 11d, 11e, 1
1f ... Precast concrete member, 12, 12c ...
Stud, 13 ... Reinforcing bar, 14 ... Bolt, 15, 15a,
15b, 15c ... Opening, 16 ... Main bar, 17 ... Long bolt

Claims (9)

[Claims] 1. A concrete block is arranged so as to be in face-to-face contact with the web on the inner side surrounded by the web and the flange with respect to a predetermined section of a steel structure member having flanges at both ends of the web, and the web is formed by the concrete block. A stiffening structure for a steel structural member, wherein local deformation of the flange due to a load acting on the steel structural member is allowed while being pressed from both sides to restrain the deformation. 2. The stiffening structure for a steel structural member according to claim 1, wherein the concrete block is also brought into contact with the inner surface of the flange to restrain the deformation of the flange toward the inner surface of the flange to some extent. 3. The stiffening structure for a steel frame structural member according to claim 2, wherein the concrete block and the flange are fixed at predetermined intervals in the longitudinal direction of the steel frame structural member to adjust the buckling length of the flange. 4. The stiffening structure for a steel structural member according to claim 1, wherein the concrete block and the inner surface of the flange are wholly or partially separated from each other. 5. The stiffening structure for a steel structural member according to claim 1, 2 or 4, wherein the concrete block is a precast concrete block. 6. The stiffening structure for a steel structural member according to claim 5, wherein the concrete block is fixed to a stiffener connecting the flanges of the steel structural member. 7. A stiffening structure for a steel structural member according to claim 1, wherein reinforcing steel is arranged in the concrete block in parallel with the flange of the steel structural member. 8. A predetermined section of a steel structure member having flanges at both ends of the web and having openings in the web and sandwiching the opening is in contact with the inside of the web and the flange surrounded by the web. A stiffening structure for a steel structural member, characterized in that the concrete blocks are arranged as described above, and the deformation of the web around the opening is constrained. 9. The stiffening structure for a steel structural member according to claim 8, wherein the concrete block is a precast concrete block having an opening formed at a position corresponding to the opening of the steel structural member.