JP2006299584A - Aseismatic reinforcing joining structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aseismatic reinforcing joining structure with improved aseismatic performance of an existing structure by a simpler means. <P>SOLUTION: This aseismatic reinforcing joining structure of the other end part of a steel fixing beam material 1 having one end fixed to a steel column 3 and a steel beam material end part 2, is characterized in that upper flanges 1a and 2a of the steel beam material end part are joined with clearance L by using an attaching plate 4a; and an axial force material 5 yielding ahead of a flange of a steel beam material is joined to an under surface of lower flanges 1b and 2b of the respective steel beam material end parts in a state of straddling the clearance L; and a restricting metal fitting 6 joined only to the lower flange of one steel beam material is arranged on an under surface of the axial force material 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the seismic reinforcement joint structure of the steel beam member end, in particular, the existing joint structure of the other end portion of the steel fixed beam member whose one end is fixed to the steel column and the end portion of the steel beam member. The present invention relates to a seismic reinforcement joint structure that is advantageous in improving seismic resistance.

  In a column-beam connection structure in a general steel structure in which a column and a beam are welded and joined in the form of a diaphragm, the welded joint at the end of the beam breaks early when a horizontal stress acts during an earthquake, etc. The entire building may collapse without exhibiting the seismic energy absorption capability that is sometimes assumed. In order to prevent such a situation, it is important to ensure the manufacturing and construction quality of the column beam joint, which has a large stress acting especially during an earthquake, in order to ensure the seismic safety of the building.

  However, in some existing structures, the quality of the beam-column joints may not be sufficiently secured, and repair work may be required to improve seismic safety. In such repair work, the scale and construction method are often limited because it is a modification of an existing structure. It is also important to minimize the repair work from the viewpoint of economy and shortening the construction period.

  Here, as an example of means for improving the earthquake resistance of the existing structure, the upper and lower flange portions of the steel beam material are appropriately cut (the broken line portion 11 in FIGS. 4 and 5), and the beam on which the greatest stress acts during an earthquake. It is possible to reduce the acting stress on the weld joint at the end and prevent early breakage of the weld joint at the beam end.

  However, when the upper and lower flange portions of the steel beam material are appropriately cut as repair work for improving the earthquake resistance of the existing structure, the workability is poor because the cutting work of the flange is very complicated. In addition, in this case, the torsional rigidity of the steel beam after the repair work is reduced, so it is necessary to take reinforcement measures to prevent the lateral buckling of the beam, which also increases the amount of work and manufacturing. There is a lot of room.

  The present invention has been made to eliminate the drawbacks of the prior art, and an object thereof is to provide a seismic reinforcing joint structure for improving the seismic safety of existing structures by a simpler means and a construction method thereof. .

(1) In the first invention, the upper flanges 1a and 2a of the end portions of the steel beam members are joined together using the attachment plate 4a with a gap L, and the yielding precedes the flanges of the steel beam members. The axial force member 5 is joined to the lower flanges 1b and 2b of the end portions of the steel beam members in a state where the gap L is straddled, and one steel is provided on the side of the axial force member 5 that does not face the beam flange surface. The other end of the steel fixed beam member 1 having one end fixed to the steel column 3 and the steel beam, characterized in that a restraint fitting 6 joined only to the lower flange of the beam member is installed. It is a seismic reinforcing joint structure with the material end 2.
(2) In the second invention, the other end of the steel fixed beam member 1 whose one end is fixed to the steel column 3 and the end of the steel beam member 2 have a gap L therebetween. About the existing joining structure joined using the installation plate 4, the lower flange and the additional plates 4b and 4c of the web are removed, and the axial force member 5 yielding ahead of the flange of the steel beam material is removed with the gap L Are joined to the lower flanges 1b and 2b of the ends of the steel beam members, and the buckling restraint material 6 of the axial force member 5 is joined only to the lower flange of one of the steel beam members. It is the construction method of the seismic reinforcement joint structure characterized by this.

  In the seismic reinforcement joint structure of the present invention, when bending acts on the beam due to an earthquake, the axial force material yielding below the bending yield load of the beam member yields ahead of the beam member, so the beam end welded joint The risk of the entire building collapsing due to the breakage caused by excessive stress is significantly reduced. In addition, the conventional method of reducing the stress at the beam end welded joint by reducing the beam flange width was inevitable to reduce the torsional rigidity of the beam, but the cross section of the axial force material that yields ahead of the beam member. By designing appropriately, it is possible to prevent the torsional rigidity of the beam from being lowered, and special reinforcement against the lateral buckling of the beam can be eliminated.

  In particular, when retrofitting with the seismic reinforcement joint structure of the present invention, the upper flange of an existing steel beam, which is usually difficult to repair due to the presence of a floor slab, is left as it is, and the lower flange part and the web part additional plate, etc. Since the repair work is completed only by bolting the axial force material and the buckling restraint material that yields prior to the beam member, the workability at the time of repair work is significantly improved.

  Hereinafter, with reference to FIG. 1 and FIG. 2, the seismic reinforcement joint structure of 1st Embodiment of this invention is demonstrated. The seismic reinforcement joint structure of the first embodiment joins the end of the steel fixed beam member 1 and the end of the steel beam member 2, one end of which is fixed to the steel column 3 by welding.

  In the seismic reinforced joint structure of the present invention, the steel fixed beam material 1 and the steel beam material 2 are both made of H-shaped steel having the same cross section, and the steel fixed beam material 1 and the steel beam material 2 are Are opposed to each other with a slight gap L at the joint.

  The upper flange 1a of the steel fixed beam member and the upper flange 2a of the steel beam member are sandwiched by the attachment plate 4a disposed vertically across the gap, and the attachment plate 4a and the upper flanges 1a, 2a Are bolted by high-strength bolts 7 and nuts 8 inserted through these members.

  Further, on the lower surfaces of the lower flange 1b of the steel fixed beam member and the lower flange 2b of the steel beam member, a low yield point steel that yields below the yield load of the flanges of the steel fixed beam member 1 and the steel beam member 2 is obtained. The damper 5 (axial force member) is bolted with the gap L straddled.

  Further, a buckling restraining metal fitting 6 having a T-shaped cross section is disposed downward on the lower surface of the low yield point steel damper connecting the lower flanges 1b, 2b with the gap L straddling. The buckling restraint fitting 6 is fixed to only one of the steel fixed beam member 1 and the steel beam member 2, and the other end portion of the buckling restraint fitting 6 is in a free state. The buckling restraint metal 6 supports the shearing force applied to the connecting portion of the beam material, and resists the downward shearing force of the beam material to which the buckling restraint metal fitting 6 is not joined. The bolt hole 9 is a bolt hole in which the beam web 1c and the beam web 2c are joined in order to transmit the shearing force of the beam material in the existing structure.

  In the seismic reinforced joint structure of the present invention configured as described above, when a tensile force or compressive force of a predetermined value or more acts on the joint, the low yield point steel damper 5 that yields below the bending yield load of the beam member is provided. The energy is absorbed by yielding in advance, and excessive stress is prevented from acting on the welded joint at the beam end.

  Further, in the seismic reinforcement joint structure of the present invention, the upper flange 1a of the steel fixed beam member and the upper flange of the steel beam member against the upward shearing force acting on the beam member to which the buckling restraint fitting 6 is not joined. The connection part with 2a resists, and the buckling restraint metal fitting 6 in the lower surface of the low yield point steel damper 5 resists a downward shearing force. Since the low yield point steel damper 5 does not reduce the torsional rigidity of the beam, the cross-sectional area is reduced by providing a long hole 5a in the center of the low yield point steel damper 5. In addition, when the shear resistance due to the bending of the joining plate on the flange side of the steel beam has sufficient resistance against the shear force acting on the beam, the buckling restraining metal fitting 6 is joined. A structure in which a downward shearing force acting on a non-beam member is resisted by an attachment plate of the upper flange of the beam, and the buckling restraint metal 6 can be configured to resist a shearing force. In this joint structure, the torsional rigidity of the beam is not lowered compared with that before the repair work, and the lateral buckling strength of the beam is not lowered by performing the repair work.

Here, when repairing the existing joint structure of the steel fixed beam member 1 and the steel beam member 2 to the seismic reinforced joint structure of the first embodiment, the following procedure is performed.
(A) First, as shown in FIGS. 4 and 5, a gap L is formed between the other end portion of the steel fixed beam member 1 having one end welded to the steel column 3 and the end portion of the steel beam member 2. For the existing joint structure that is joined using the attachment plate in the state of holding, the attachment plate 4a, 4c of the upper flange portion and the web portion, the high strength bolt 7 and the like are left, and the attachment of the lower flange portion is provided. The plate 4b and the high strength bolt 7 are removed.
(B) Next, in a state where the gap between the steel fixed beam member 1 and the steel beam member 2 is straddled, the lower yield of the lower flange 1b of the steel fixed beam member and the lower flange 2b of the steel beam member is reduced. A spot steel damper 5 (axial force material) is arranged. In addition, a restraining metal fitting 6 is disposed on the lower surface of the low yield point steel damper 5 in a state of straddling the gap L between the steel fixed beam material 1 and the steel beam material 2.
The low yield point steel damper 5 is bolted to both the steel fixed beam material 1 and the steel beam material 2, but the restraint fitting 6 is either the steel fixed beam material 1 or the steel beam material 2. The other end of the restraint fitting is free.
(C) Then, after fixing the low-yield point steel damper 5 and the restraint fitting 6, the web 4c, the high-strength bolt 7 and the like are removed, and the construction of the seismic reinforcement joint structure is completed.

  That is, when the existing joint structure of the steel fixed beam member 1 and the steel beam member 2 is modified to the seismic reinforced joint structure of the present invention, the attachment plate 4b of the lower flange portion and the web portion of the existing joint structure, The repair work is completed simply by removing 4c and the like and bolting the low yield point steel damper 5 and the restraint fitting 6 together. Therefore, both the upper and lower flanges of the beam, including the upper flange side of the beam, which is difficult to repair due to the presence of a floor slab as in the prior art, are cut, and a lateral stiffener is used to prevent lateral buckling of the beam. Compared to the case of mounting, the work is easier and the workability during repair work is significantly improved.

FIG. 3 is a side view of the second embodiment of the present invention.
In the second embodiment of the present invention, a pair of buckling restraining members 6a, as a buckling restraining metal fitting for the axial force members 5b and 5c that yield in advance from the steel beam members attached to the upper and lower surfaces of the lower flange of the steel beam, 6b is used. The attachment plate 4a on the lower surface side of the upper flange of the beam is reinforced with a rib 10 joined by welding so as to be able to resist the shearing force acting on the beam. Other components are the same as those in the first embodiment, and the same reference numerals are given and description thereof is omitted.

  In the second embodiment, one end is fixed to the steel column at the axial force member 5 that yields ahead of the steel beam member attached to the lower flange 1b of the steel fixed beam member and the lower flange 2b of the steel beam member. The buckling restraining members 6a and 6b are bolted to the steel beam member side so as to form a pair. Buckling at the time of compressive stress action of axial force members 5b and 5c supported by the upper flange side attachment plate 4a reinforced with ribs 10 and shearing force applied to the connecting portion of the beam material and yielding ahead from the steel beam member The buckling restraining members 6a and 6b restrain the buckling.

It is the side view and sectional drawing of the earthquake-proof reinforcement joining structure of 1st Embodiment of this invention. It is a bottom view of the earthquake-proof reinforcement joining structure of 1st Embodiment of this invention. It is a bottom view of the earthquake-proof reinforcement joining structure of 2nd Embodiment of this invention. It is a side view which shows the existing joining structure using the attachment board of steel fixed beam materials and steel beam materials, and the repair construction state of a prior art. FIG. 5 is a plan view of FIG. 4.

Explanation of symbols

1 Steel fixed beam 1a Upper flange 1b Lower flange 1c Web 2 Steel beam 2a Upper flange 2b Lower flange 2c Web 3 Steel pillar 4 Additional plate 4a Upper flange additional plate 4b Lower flange additional plate 4c Web additional Installation plate 5 Axial force member 5a that yields from steel beam member in advance Yield of axial force member 5b that precedes yield from steel beam member 5c Axial member 6 that yields from steel beam member 6 Buckling restraint metal fitting 6a, 6b Buckling Restraint Bracket 7 High Strength Bolt 8 Nut 9 Bolt Hole 10 to which the Web Joining Plate was Joined 10 Reinforcement Rib of the Joining Plate on the Lower Side of the Upper Flange 11 Flange Cutting Part L Steel Fixed Beam Material-Steel Beam Spacing between materials

Claims (2)

Each steel beam member is joined in a state where the upper flanges of the end portions of the steel beam members are joined together with an attachment plate with a gap, and the axial force material yielding ahead of the steel beam member straddles the gap. It is joined to the lower flange of the end, and the restraint fitting joined only to the lower flange of one steel beam material is installed on the side of the axial force member that does not face the beam flange. A seismic reinforcement joint structure between the other end of the steel fixed beam member and one end of the steel beam member, one end of which is fixed to the steel column. Regarding the existing joint structure in which the other end of the steel fixed beam member, one end of which is fixed to the steel column, and the end of the steel beam member are joined using an attachment plate with a gap between them, The lower flange and the web attachment plate are removed, and the axial force material yielding ahead of the flange of the steel beam material is joined to the lower flange of each steel beam material end in a state straddling the gap, A method for constructing a seismic reinforced joint structure characterized in that a buckling restraint material for axial force members is installed only on the lower flange of one steel beam member.

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