JP4771161B2 - Joint structure of steel column and steel beam - Google Patents

Description

  The present invention relates to a steel building and relates to a structure for joining a steel beam to a steel column via a bracket having a damper function.

As is well known, in general, a steel building is designed to have a beam-yield-preceding type and requires an energy absorption capability by plastic deformation at the end of the beam. For example, as shown in Patent Document 1 The beam and the column are joined to each other through a bracket for forming a plastic hinge at the beam end.
For example, Patent Document 2 proposes a structure that obtains an energy absorption effect by shear yielding the web itself at the end of the H-shaped steel as a beam.
Japanese Patent Laid-Open No. 11-140978 JP 2005-330679 A

However, since what is shown in Patent Document 1 is simply to join a beam to a column via a bracket having the same cross section as the beam, the energy absorption effect by the bracket may not always be obtained sufficiently.
Moreover, in recent design methods, there is a tendency to use higher strength steel materials. However, since the plastic deformation ability of such high strength steel materials decreases conversely, the beam itself as shown in Patent Document 2 is used. The design method of plastic deformation is difficult to adopt.

  In view of the above circumstances, an object of the present invention is to provide an effective and appropriate joint structure that can sufficiently ensure the energy absorption capability at the beam end.

  The present invention is a structure for joining a steel beam to a steel column, wherein a bracket having a damper function is interposed between the steel beam and the steel column, and the bracket is fixed to the steel column. And a shear panel made of a steel plate provided between the flanges, the bending rigidity and bending strength of the entire bracket are set to be larger than those of the steel beam, and the shear panel is sheared and yielded before the steel beam. The steel beam is connected to the steel column via the bracket by pin-joining the steel beam to the two locations of the base portion and the tip portion of the bracket in a state where shearing force can be transmitted. It is characterized by being rigidly joined in terms of structural mechanics.

  The structure of the bracket and the steel beam in the present invention is arbitrary. For example, the base end portion of the shear panel, which is a component of the bracket, is welded to the steel column, and the base panel and the front end portion of the shear panel are attached to both sides of the shear panel. It can be considered that a pair of channel-shaped steel webs to be steel beams are fastened with bolts via a backing plate.

  Alternatively, the shear panel, which is a component of the bracket, is arranged on both sides of the end of the H-shaped steel as a steel beam as a damper unit, and the base of the damper unit is bolted to the steel column via a shear plate and a backing plate In addition, the upper and lower portions of the damper unit are bolted to the upper and lower flanges that are the components of the bracket, and the end of the H-shaped steel as the steel beam is connected to the steel column via the joining plate that is the component of the bracket On the other hand, it is also conceivable to fasten the bolt via the joining plate and to fasten the tip of the damper unit to the vertical rib welded to the side of the H-shaped steel.

It is also conceivable that the steel beam is composed of a main body portion and a joining end portion fastened to the tip end portion thereof, and the tip end portion of the joining end portion is rigidly joined by pin joining to two places of the bracket.
In that case, the main part of the steel beam is made up of an H-shape, and the joint end of the steel beam is made up of a pair of channel-shaped steels sandwiching the H-shaped steel from both sides. It is preferable that the channel-shaped steel webs and the flanges as the joining end portions are rigidly joined by bolting via a contact plate.

  According to the present invention, the shear force acting on the steel beam is expanded by the “lever principle” and transmitted to the bracket to shear yield the shear panel, thereby making the shear panel exhibit a damper function and having an excellent energy absorption effect. can get. Even in the event of a major earthquake, the steel frame and the steel frame itself will not be plastically deformed and will remain elastic, so there will be no damage to the main frame, and the steel beam will become a steel column even after the shear panel yields shear. On the other hand, the load support ability of the steel beam is not lost because it is simply supported, so that the fail-safe mechanism is automatically formed.

First, the basic structure and basic principle of the present invention will be described with reference to FIG.
As schematically shown in FIG. 1, in the present invention, a steel beam 2 is joined to a steel column 1 via a bracket 3. As a premise, both the steel column 1 and the steel beam 2 are subjected to a large earthquake. It shall maintain elasticity without yielding at times.
The bracket 3 has a shear panel (details will be described later) that functions as a hysteresis damper by shear yielding. The bending rigidity and bending strength of the bracket 3 as a whole are set larger than those of the steel beam 2, but the shear panel of the bracket 3 Is set to shear yield before the steel beam 2.
Then, the ends of the steel beam 2 are pin-bonded to the two portions of the base 3 and the tip of the bracket 3 via bolts, respectively, so that the connection form of the steel beam 2 to the steel column 1 is structurally rigid. Joined. Further, relative rotation in the in-plane direction of the steel beam 2 with respect to the steel column 1 and the bracket 3 is allowed at each pin joint position.

According to such a joint structure, when the shearing force at the center of the steel beam 2 is Q ₀ and the length of the bracket 3 (projecting dimension from the steel column 1) L _J , the shear generated at the end of the bracket 3 Force _B Q _E is
_B Q _E = (M _J / L _J ) + Q ₀
And it also becomes large several times than shear force Q ₀ at the central portion of the steel beam 2 (because the influence of long-term stress is generally small, neglected here).
In other words, this joint structure forms a “shear force transmission mechanism” using the “lever principle”, and shearing the shear panel by expanding the shear force acting on the steel beam 2 and transmitting it to the bracket 3. Yield, thereby causing the shear panel to exert a damper function and obtain an energy absorption effect.
Therefore, according to the joint structure of the present invention, it is possible to remarkably increase the energy absorption capacity as compared with the case where the shear force of the beam is applied to the bracket as it is (without expanding) and yielded.
In this case, the apparent beam end moment is determined by multiplying the load shearing force _B Q _E of the bracket 3 by the length L _J of the bracket 3, and the beam end moment M _E is set to the peak due to the shear yield of the shear panel. Therefore, even if the steel beam 2 maintains elasticity, the stress state is the same as when a plastic hinge is generated at the beam end.
In this joint structure, the main frame itself by the steel column 1 and the steel beam 2 remains elastic without plastic deformation even in the event of a large earthquake, so that the main frame is not damaged, and even after the shear panel is shear yielded. Since the steel beam 2 is simply supported with respect to the steel column 1 and the load supporting ability of the steel beam 2 is not lost, the fail-safe mechanism is naturally configured.

  A specific first embodiment of the joining structure of the present invention based on the above principle is shown in FIGS. In the first embodiment, a steel beam 2 made of a pair of channel steels is joined to a steel column 1 made of a square steel pipe via a bracket 3.

The bracket 3 in the first embodiment includes an upper and lower flange 4 and a shear panel 5 provided between the upper and lower flanges 4.
The upper and lower flanges 4 are formed integrally with a diaphragm welded to the steel column 1 and are formed so as to project radially from the diaphragm in each of the surrounding directions (in the illustrated example, in a cross shape so as to project in four directions). Has been. The shear panel 5 is a rectangular flat steel plate made of low yield point steel, and its base end is welded to the steel column 1 and its top and bottom are welded to the top and bottom flanges 4 and a diaphragm integral therewith. ing.
As a result, the bracket 3 of the present embodiment is formed in such a manner that the protruding portion of the H-shaped cross section by the upper and lower flanges 4 and the shear panel 5 protrudes radially around the steel column 1 as described above. The cross-section of the upper and lower flanges 4 is such that the overall bending rigidity and bending strength of the bracket 3 is greater than that of the steel beam 2 and that the shear panel 5 of the bracket 3 is sheared and yielded prior to the steel beam 2. The dimensions and the strength and strength of the low yield point steel as the shear panel 5 are set appropriately.

The steel beam 2 in the present embodiment is an assembled beam in which a pair of channel shape steels 2a are back to back and the main points are connected by a binding material 6, and the tip of each channel shape steel 2a passes through the shear panel 5 from both sides. Although it is joined to the bracket 3 in a sandwiched state, the joint plate 7 is joined by a plurality of bolt groups (six in the illustrated example) at two locations of the base portion and the tip portion of the shear panel 5 respectively. It is done by bolting through. As a result, the form of joining of the steel beam 2 to the steel column 1 via the bracket 3 is rigidly connected in terms of structural mechanics, but the steel beam to the steel column 1 and the bracket 3 in the event of an earthquake exceeding the assumed scale. The relative rotation in the in-plane direction of the shear panel 2 is allowed without restriction.
In addition, although the front-end | tip part of the channel shape steel 2a as the steel beam 2 will be inserted between the upper and lower flanges 4 which comprise the bracket 3, as mentioned above, rotation of the steel beam 2 in the shear panel surface direction is carried out. Therefore, a slight clearance is secured between each channel shape steel 2a and the flange 4. At the same time, since the periphery of the shear panel 5 is constrained and stiffened by the backing plate 7 and the upper and lower flanges 4, a clear shear deformation region is formed on the inside thereof, and an ideal shear yield can be generated. It has become.

According to the first embodiment, as described above, the shear stress of the steel beam 2 is expanded by the “lever principle” and acts on the shear panel 5, and an excellent damper effect due to the shear yield of the shear panel 5, that is, energy absorption. An effect is obtained.
Of course, it is possible to freely and widely adjust the stress that it bears by setting the dimensions (sheet thickness, height, length) and grade of the low yield point steel as the shear panel 5, and its plastic deformation ability If it is set sufficiently high, it will not be destroyed even in a large earthquake, and therefore it is unlikely that the shear panel 5 needs to be replaced after a large earthquake.
In addition to the main frame, the bracket 3 also maintains elasticity without yielding except for the shear panel 5, so the residual deformation after the earthquake is small. In particular, since the shear yield strain γ of the low yield steel used as Shiyapaneru 5 is about 1.6 × 10 ^-3, when the length L _J bracket 3 is 600mm for example at yield at its distal end The vertical displacement of the slab is only about 1mm, so the floor slab is expected to be deformed slightly when a medium-scale earthquake is applied that causes the shear panel 5 to start yielding, causing damage such as cracking. It can be said that there is no.

  And in this 1st Embodiment, since the low yield point steel of a simple rectangular flat plate shape is employ | adopted as the shear panel 5, the process of the bracket 3 can be performed easily and cheaply, and a diaphragm is provided with respect to the steel column 1 Except for welding the flange 4 which also serves as the shear panel 5, all can be assembled only by fastening bolts, so it is possible to eliminate on-site welding and to improve the efficiency and labor saving of on-site work. Of course, the height of the bracket 3 can be accommodated within a range that is slightly larger than the beam dimension of the steel beam 2, so there is no need to secure a special space for installing the bracket 3. 3 is installed, the effective floor height and effective ceiling height are not lowered.

Next, a second embodiment will be described with reference to FIGS.
The second embodiment employs a damper unit 10 in which a shear panel 5 is incorporated, and the two damper units 10 are fixed with an interval between the upper and lower flanges 4, and the upper and lower flanges 4 and the left and right damper units 10 are used. A box-shaped bracket 3 is formed, and an end portion of an H-shaped steel 2b as a steel beam 2 is inserted into the bracket 3, and the tip portion thereof is a bolt group at two locations of the base portion and the tip portion of the bracket 3, respectively. Thus, pin bonding is substantially performed.
That is, the bracket 3 in the second embodiment is mainly composed of the upper and lower flanges 4 and the pair of left and right damper units 10 similar to those in the first embodiment, and these damper units 10 are attached to the steel column 1. A shear plate 11 for fastening the bolt and a joining plate 12 for fastening the web of the H-shaped steel 2b as the steel beam 2 to the steel column 1 by bolts.

As in the first embodiment, the damper unit 10 is mainly composed of a rectangular flat shear panel 5 made of a steel plate made of low yield point steel, and steel frame members 10a and 10b are welded to the upper and lower sides and the tip side, respectively. The base portion of the shear panel 5 is bolted to the above-described shear plate 11 via the contact plate 7, and the upper and lower frame members 10 a are bolted to the upper and lower flanges 4. A box-shaped bracket 3 is configured together with the flange 4.
Prior to joining the damper unit 10 to the shear plate 5, the steel beam 2 is carried in, and the tip of the web is bolted to the joining plate 12 with a group of bolts and welded to the side of the steel beam 2. The frame member 10b on the front end side of the damper unit 10 is bolted to the vertical rib 13 with a group of bolts.
As a result, the tip of the steel beam 2 is substantially pin-bonded to the steel column 1 via the joining plate 12 that is a component of the bracket 3, and the damper unit 10 that is also a component of the bracket 3. The front end portion is also substantially pin-bonded via the vertical rib 13.
Also in the second embodiment, as in the case of the first embodiment, the steel beam 2 is pin-bonded in a state where the steel beam 2 can be relatively rotated at two locations with respect to the bracket 3 having the shear panel 5 that functions as a damper by shear yielding. As a result, the steel beam 2 is structurally rigidly connected to the steel column 1. Therefore, as in the first embodiment, the shear stress of the steel beam 2 is expanded by the lever principle and transmitted to the shear panel 5, and an excellent damper effect, that is, an energy absorption effect due to the shear yield of the shear panel 5 is obtained. .
And although the structure of the bracket 3 is a little complicated compared with 1st Embodiment, since it has the two shear panels 5, the design which raises an energy absorption effect as a whole is possible.

  7 to 8 show a third embodiment. In the third embodiment, the steel beam 2 is composed of a main body portion made of an H-shaped steel 21 and a pair of channel-shaped steels 22 integrally fastened as a joining end portion to the distal end portion of the H-shaped steel 21. A tip end portion of the channel shape steel 22 as a joining end portion is pin-joined to the bracket 3 at two locations.

That is, in the first embodiment, the total length of the steel beam 2 is configured by the channel shape steel 2a, and in the second embodiment, the total length of the steel beam 2 is configured by the H-shaped steel 2b. In 3 embodiment, the steel beam 2 is comprised by combining the H-section steel 21 and the channel shape steel 22. As shown in FIG. Then, both the webs and the flanges are fastened with a large number of bolts through the contact plate 23 in a state in which the distal end portion of the H-shaped steel 21 is sandwiched from both sides by the base end portions of the pair of channel shape steels 22. Both of them are rigidly joined structurally, and the shearing force acting on the entire steel beam 2 can be transmitted to the bracket 3 without any trouble.
As shown in the figure, an appropriate spacer 24 is interposed between the web of the pair of channel shape steels 22 and between the web of the H-shaped steel 21 and the contact plate 23 as necessary. The H-shaped steel 21 and the channel shaped steel 22 may be provided with reinforcing ribs 25 at appropriate positions as necessary. Furthermore, it is also preferable to provide a reinforcing plate 30 at the tip of the bracket 3 as necessary.

Further, in the first to second embodiments, the steel beam 2 is joined to the two locations of the bracket 3 by a large number of bolt groups (six in the illustrated example). Only two small bolts in total of two are used for joining, so that a shear force expansion transmission mechanism using the “leverage principle” as shown in FIG. 1 is provided in the first and second embodiments. Compared to the case, it is constructed more effectively, and a sufficient damper effect can be obtained by reliably expanding the shearing force acting on the steel beam 2 and transmitting it to the bracket 3. .
In order to effectively form a shear force expansion transmission mechanism by pin-bonding the steel beam 2 to the bracket 3 at two locations as described above, the upper and lower surfaces of the steel beam 2 and the bracket 3 are as described above. It is necessary to allow relative rotation in the direction, and for that purpose, it is preferable to allow some relative displacement in the horizontal direction while reliably restraining the relative displacement in the vertical direction. The holes are preferably loose holes that are slightly long in the horizontal direction. This applies not only to the third embodiment but also to each group of bolts in the case of the first to second embodiments.

In this 3rd Embodiment, since the steel beam 2 was comprised with the H-section steel 21 as a main-body part, and the channel shape steel 22 as a joining edge part, the construction is also shown to Fig.8 (a)-(b). The procedure shown can be performed efficiently.
That is, at the time of construction, a channel shape steel 22 as a joint end portion is first attached to the bracket 3 previously welded to the steel column 1 as shown in (a), and then as shown in (b). When the H-shaped steel 21 is bolted to the channel shaped steel 22, the entire steel beam 2 is lifted up and positioned and joined to the bracket 3 as in the first to second embodiments. Compared with this, workability can be improved and sufficient construction accuracy can be secured.
Prior to welding the bracket 3 to the steel column 1, it is conceivable that the channel shape steel 22 is also attached to the bracket 3 in advance, and when the steel column 1 is manufactured at the factory, the bracket 3 is welded together. It is also conceivable to attach the channel shape steel 22 to the bracket 3 at the factory.

Next, FIGS. 9 to 11 show a fourth embodiment. This is based on the third embodiment, and the steel beam 2 is joined to the two places of the bracket 3 by the pin mechanism 40 without using a plurality of bolts. Compared to the above, a simpler and clearer shear force expansion transmission mechanism is constructed.
As the pin mechanism 40, for example, as shown in FIG. 10, a short cylindrical steel pin 41 is used as a main component, and pressing plates 42 are attached to the outer sides of both ends and welded, or a substantially octagonal cross section as shown in FIG. A type in which the inner peripheral edge portion of the center hole of the pressing plate 42 is welded to both end surfaces of the steel pin 41 can be suitably used. In any case, at least one pressing plate 42 is used as the steel pin 41. It is only necessary to weld after mounting.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, the configuration of the bracket 3 and the form of joining the steel beam 2 to the bracket 3 depart from the gist of the present invention. As long as it is configured so that the shearing force acting on the steel beam 2 is expanded and transmitted to the bracket 3 functioning as a damper within the range not to be used, that is, using the “lever principle”, any design change is possible. Needless to say.
For example, in the above-described embodiment, the steel beam 2 is an assembly beam made of the channel shape steel 2a, the H-shape steel 2b, and the combination of the H-shape steel 21 and the channel shape steel 22, but the steel beam 2 is not limited thereto. Of course, the steel column 1 can be not only a square steel tube column but also a normal steel column made of a shape steel such as a round steel tube column or H-shaped steel, and a concrete-filled steel tube column.
Moreover, in each said embodiment, although the shear panel 5 was made into the rectangular flat plate shape which consists of low-yield point steel, the shear panel 5 should just be a steel plate which shears and yields ahead of the steel beam 2, and sets it like that. As long as the shape, dimensions, and material of the shear panel 5 are arbitrary, it is possible to employ, for example, ordinary mild steel. In this case, the damper effect is somewhat reduced, but the cost can be reduced.

It is a schematic diagram for demonstrating the basic structure and basic principle of this invention. It is a figure which shows the principal part of 1st Embodiment of this invention, (a) is a side view (aa arrow directional view in (b)), (b) is a plane sectional view (bb in (a). (Arrow view) and (c) are front sectional views (cc view in (a)). FIG. It is a figure which shows the principal part of 2nd Embodiment of this invention, (a) is a sectional side view (aa arrow directional view in (b)), (b) is a plane sectional view (b-in (a). (b arrow view) and (c) are front sectional views (cc arrow view in (a)). It is a figure which shows another principal part same as the above, (a) is a side view (Va-Va arrow view in FIG.4 (b)), (b) is a front sectional view (bb arrow view in (a). Figure). FIG. It is a figure which shows the principal part of 3rd Embodiment of this invention, (a) is a side view, (b) is a plane sectional view (the bb arrow line view in (a)), (c) is a front sectional view. (Cc arrow view in (a)), (d) is a front sectional view (dd arrow view in (a)). It is a figure which shows a construction procedure, (a) is the state which joins the channel shape steel as a joining end part of a steel beam to a bracket, (b) is the H shape steel as the main-body part of a steel beam. It is a figure which shows the state joined to. It is a figure which shows the principal part of 4th Embodiment of this invention, (a) is a side view, (b) is a plane sectional view (the bb arrow line view in (a)), (c) is a front sectional view. (C-c arrow view in (a)). It is a figure which shows an example of a pin mechanism similarly. It is a figure which shows the other example of a pin mechanism similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel column 2 Steel beam 2a Channel shape steel 2b H-shape steel 3 Bracket 4 Flange 5 Shear panel 6 Binding material 7 Base plate 10 Damper unit 10a Frame material 10b Frame material 11 Shear plate 12 Joining plate 13 Vertical rib 21 H-shaped steel (steel frame The main body of the beam)
22 Channel steel (joint end of steel beam)
23 Retaining plate 24 Spacer 25 Reinforcement rib 30 Reinforcement plate 40 Pin mechanism 41 Steel pin 42 Holding plate

Claims (5)

A structure for joining a steel beam to a steel column,
A bracket having a damper function is interposed between the steel beam and the steel column,
The bracket has an upper and lower flange fixed to a steel column and a shear panel made of a steel plate provided between the flanges, and the bending rigidity and bending strength of the entire bracket are set larger than those of a steel beam, Set the shear panel on the bracket to shear yield before the steel beam,
The steel beam is structurally rigid with respect to the steel column via the bracket by pin-bonding the steel beam to the base and the tip of the bracket in a state where shear force can be transmitted. A joining structure of a steel column and a steel beam, characterized by being joined. It is a joining structure of the steel column and steel beam according to claim 1,
The base end of the shear panel, which is a component of the bracket, is welded to the steel column, and a pair of channel-shaped steel webs as steel beams are attached to both sides of the shear panel at the base and tip of the shear panel, respectively. A structure for joining a steel column and a steel beam, wherein the steel column is fastened with a bolt. It is a joining structure of the steel column and steel beam according to claim 1,
Shear panels, which are components of the bracket, are arranged on both sides of the end of the H-shaped steel as a steel beam as a damper unit, and the base of the damper unit is bolted to the steel column via a shear plate and a backing plate. The upper and lower sides of the damper unit are bolted to the upper and lower flanges which are the components of the bracket, and the end of the H-shaped steel as the steel beam is connected to the steel column via the joining plate which is the component of the bracket A structure for joining a steel column and a steel beam, wherein the steel rib and the steel beam are fastened with bolts, and the tip of the damper unit is bolted to a vertical rib welded to the side of the H-shaped steel. It is a joining structure of the steel column and steel beam according to claim 1,
The steel beam is composed of a main body portion and a joining end portion fastened to the tip end portion thereof, and the tip end portion of the joining end portion is rigidly joined by pin joining to two places of the bracket. Joint structure of steel column and steel beam. It is a joining structure of a steel column and a steel beam according to claim 4,
The main part of the steel beam is made of H-shaped steel, and the joint end of the steel beam is made of a pair of channel-shaped steels sandwiching the main body from both sides. The H-shaped steel as the main part and the channel shaped steel as the joined end A steel column-to-steel beam connection structure characterized in that the webs and flanges are rigidly joined by fastening bolts via a backing plate.

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