WO2010103812A1

WO2010103812A1 - Seismic resistant steel structure

Info

Publication number: WO2010103812A1
Application number: PCT/JP2010/001666
Authority: WO
Inventors: 鈴木孝彦; 鈴木悠介; 竹内一郎; 岡田忠義
Original assignee: 新日本製鐵株式会社
Priority date: 2009-03-12
Filing date: 2010-03-09
Publication date: 2010-09-16
Also published as: TW201116687A; JPWO2010103812A1

Abstract

An underground steel structure which supports a building having a ground column has an underground wall, an underground column provided below the column base of the ground column, and an external beam coupling the column base and the underground wall and having a yield point lower than that of the column base.

Description

Seismic steel structure

The present invention relates to a seismic steel frame structure such as a multi-layer building having a subway frame structure.
This application claims priority based on Japanese Patent Application No. 2009-058936 filed in Japan on March 12, 2009, the contents of which are incorporated herein by reference.

Conventionally, a multi-layered building having a subway bone structure is known (see, for example, Patent Document 1).
FIG. 11 shows a multi-layered building 104 with a ramen structure having a subway bone structure 115. For example, when a horizontal force is applied to the multi-layered building 104 during an earthquake, the ground steel structure on the second floor or higher can move in the horizontal direction. Therefore, as shown in FIG. 14, bending moments M <b> 1 and M <b> 2 that are markedly smaller than the ground column base part 106 act on the columns 101 and the beams 102 provided on the second floor or higher.
FIG. 13 is a schematic view for explaining a general subway bone structure 115. As shown in FIG. 13, the subway bone structure 115 includes an SRC or RC underground outer peripheral wall 105 provided in the ground outside the side pillar 101 a or the corner pillar 101 b on the ground, and a first-floor ceiling slab 112. The outer beam 102a to support and the first floor beam 102 are provided. One end of the outer beam 102a is connected to the underground outer peripheral wall 105, and the other end of the outer beam 102a is connected to the column base of the ground side column 101a or the ground corner column 101b. The first floor beam 102 is between the legs of the ground side pillar 101a, between the legs of the ground side pillar 101a and the legs of the corner pillar 101b, or between the legs of the ground side pillar 101a and the middle pillar 101c. Connect between the legs.
As shown in FIG. 14, when a horizontal force as indicated by an arrow acts on the building 104 during an earthquake or the like, the underground outer peripheral wall 105 restrained by the ground G moves in the horizontal direction together with the ground G. Therefore, a large reverse shear bending moment M3 acts on the joint between the column base of the ground column 1 to which the outer beam 102a is connected and the upper part of the first basement column 101d.
The subway bone structure 115 is constructed so as to have high rigidity, and, for example, SRC construction is adopted.

As described above, when a horizontal force acts on the building 104, a large reverse shear bending moment M3 is generated at the joint between the column base of the ground column 1 and the upper part of the first basement column 101d. In order to counter this bending moment M3, it is conceivable to design the plastic deformation performance of the ground column 101 and the underground first floor column 101d to be large. Specifically, it is considered to use a steel material having a yield ratio of 80% or less as the material of the column, or to design the plate thickness t2 of the square steel pipe column 113 to be thick as shown in FIGS. 12A and 12B. It is done.

In addition, the seismic design of architectural frames, especially ramen frames in which columns and beams are rigidly connected, is (1) to exhibit the seismic function by elastic deformation of the frame during small and medium earthquakes, and (2) The basic idea is to exert an earthquake-resistant function by plastic deformation. More specifically, in (2), in anticipation of energy absorption performance by plastic deformation of the frame, plastic deformation is allowed to exhibit an earthquake resistance function. That is, the design strength is reduced by the plastic deformation performance.

To absorb a large earthquake, it is necessary to absorb more energy. Therefore, generally, as a member constituting the framework, a plastic deformation property is improved by using a low YR steel material having a ratio YR (= YP / TS) between the yield point YP and the tensile strength TS of 0.80 or less. . Moreover, it is recommended that the collapse mode of the frame be an overall collapse mode suitable for energy absorption.

For example, in Non-Patent Document 1, it is recommended to set the column beam strength ratio to 1.5 or more at each node in order to realize the overall collapse mode. The column beam strength ratio is a numerical value used as an index for judging the collapse mechanism, and is a value obtained by dividing the column strength by the beam strength.

Collapse modes are broadly divided into partial collapse modes in which all the columns of a layer are yielded in advance and one or more specific layers are collapsed, and overall collapse modes in which beams are yielded in advance and plastic hinges are dispersed in all layers. The

In the partial collapse mode in which all the columns in a layer yield in advance, the collapse occurs even if the number of generated plastic hinges is small.

On the other hand, in the overall collapse mode in which the beam yields in advance, the collapse occurs when the plastic hinge is formed in all layers. Therefore, when a member having the same plastic deformation performance is used for the column and the beam, the energy absorption capacity of the frame is higher in the overall collapse mode than in the partial collapse mode (see, for example, Patent Document 2).
A design in which the column beam strength ratio exceeds 1.0 is also known (see, for example, Patent Documents 3 and 4).

In a multi-layer building structure, a technique is also known in which diagonal members using low-yield point steel are provided in a portion surrounded by a beam on the upper floor, a beam on the lower floor, and a column connected thereto. This diagonal material connects the upper-level beam (or the corner portion where the upper-level column beam intersects) and the corner portion where the lower-level beam beam intersects. According to this technique, since the diagonal member yields ahead of the column and the beam, the column and the beam can be kept within the range of elastic deformation. It is also known to design a framework so that seismic energy input to a building that could not be absorbed by the diagonal material is absorbed by plastically deforming the beam member before the column.

As an example of the above-mentioned framework design, a steel plate having a tensile strength of 200 N / mm grade ² to 300 N / mm grade ² (each design strength is 80 N / mm grade ² to 205 N / mm grade ² ) is used for the diagonal member. A steel plate having a tensile strength of 400 N / mm class ² (400 to 590 N / mm class ² (each design strength is 325 N / mm class ² to 440 N / mm class ² )) is used for the beam member or column member. Further, a part of the upper and lower flanges in the axial direction of the beam is joined with a cross-sectional area smaller than the other parts, or a steel material having a low yield point is interposed at the joint between the column side flange and the beam. By designing the framework in this way, it is possible to yield a beam provided with a part that is easily plastically deformed in advance of the column. As a result, the column can be used within the range of elastic deformation.

For the column member, a steel material having the same tensile strength as the steel plate for the beam member is used. In addition, a vertical compressive load is greatly applied to the pillar on the lower floor. Therefore, the higher the building, the larger the cross-sectional area of the column on the lower floor, such as the box cross-section, and the greater the steel weight. In this case, high skill and quality control are required for welding.

By the way, a ramen structure composed of a square steel pipe column and an H-shaped cross-section beam is adopted in many steel-framed buildings. The rectangular steel pipe column is often manufactured by assembling thick plates by welding.
As described above, as a column material when a column is used within the elastic range, a steel material having higher design strength and toughness (brittle fracture resistance) is required rather than plastic deformation performance. However, when a steel material having a high design strength is used to increase the tensile strength by increasing the amount of hardening strengthening elements such as carbon, the weldability of the steel material deteriorates. This increases the frequency of hardening of the weld heat affected zone and weld cracks.
In addition, when welding is performed by preheating the columns in order to prevent hardening and cracking, the construction cost is high and it is not economical. When using a general steel material that does not require preheating (design strength: 235 to 325 N / mm class ² ), the thickness of each side plate that forms the square steel pipe column becomes thick, and a lot of weld metal is required. The steel weight of the steel pipe column becomes heavy. As a result, the weight of the building increases and the cost increases.

In a steel structure building, the column is used in the elastic range, and the beam is designed to yield before the column, thereby preventing damage to the column during a large earthquake and preventing collapse of the building. It is also known to do so (see, for example, Patent Documents 2 to 5).

Japanese Patent Laid-Open No. 11-336101 JP 2006-291698 A JP 2006-45821 A JP 2006-45820 A Japanese Patent No. 3888244

When high yield point steel is used for a column to reduce construction costs, the column is likely to break early due to an increase in yield ratio and a decrease in elongation. Therefore, an earthquake-resistant steel structure that prevents early breakage of the column is desired.
With the exception of the ground column base and the upper part of the underground column, by securing the column beam strength ratio above a certain value, the beam yields ahead of the column and the column stays within the elastic range to prevent the column from breaking. it can. However, in general, the ground column base is rigidly joined to the underground structure portion, and therefore a reverse shear moment M3 is generated when a horizontal force is applied to the building. For this reason, the outer beam (first floor beam) connected to the ground column base cannot be yielded in advance, and it is difficult to keep the ground column base within the range of elastic deformation.

As described above, a large reverse shear bending moment M3 is applied to the ground column 101 and the underground column 101d. For this reason, if the bending moment M3 of the reverse shear can be eliminated, it is possible to use the column within the elastic range even if a steel material (high tensile steel) having a high yield ratio is used as the column material. As a result, the column cross-sectional area can be reduced. That is, it becomes possible to reduce the steel weight of the column, and the building can be constructed at a lower cost.
An object of this invention is to provide the earthquake-resistant steel structure which can eliminate the said subject.

The present invention employs the following means in order to solve the above-described problems.
(1) A first aspect of the present invention is a subway skeleton structure for supporting a building having a ground column, an underground wall; an underground column provided below a column base of the ground column; and the column base And an outer beam connecting the basement wall and a lower yield point than the column base.
(2) In the subway frame structure described in (1) above, the outer beam may include a damper portion having a lower yield point than the outer beam.
(3) In the subway frame structure described in (2) above, the damper portion may be a steel material joined in series in the axial direction of the outer beam.
(4) In the subway bone structure described in (2) above, the damper portion may be a steel plate interposed between the outer beam and the ground column.
(5) In the subway bone structure described in (1) above, the yield strength of the above-mentioned ground column and the above-mentioned underground column may be at least 400 N / mm ² .
(6) In the subway bone structure described in any one of (1) to (5) above, the column base portion of the ground column and the underground column may be joined by a pin joint structure. .

According to the configuration described in (1) above, since the outer beam yields before the column base of the ground column, plastic deformation of the column base of the ground column can be prevented. For this reason, for example, when a horizontal force is applied to the ground steel structure due to an earthquake or the like, the bending moment M3 generated in the column base portion of the ground column can be absorbed by the plastic deformation of the outer beam. Therefore, even if a steel material (high-tensile steel) with a high yield ratio is used as the material for the above ground column and underground column, the column can be used within the elastic range. As a result, the column cross-sectional area can be reduced, and the steel weight of the column can be reduced. Therefore, a building can be constructed at a lower cost.
According to the configurations described in the above (2) to (4), the outer beam can be moved in the horizontal direction because the damper portion expands and contracts when a horizontal force is applied to the ground steel structure due to, for example, an earthquake. Moreover, the bending moment M3 generated in the column base portion of the ground column can be absorbed by the plastic deformation of the damper portion. Furthermore, when an external force is received due to an earthquake or the like in which the damper portion is plastically deformed and the outer beam is not plastically deformed, it can be repaired by replacing only the damper portion.
According to the configuration described in (5) above, since the yield strength of the column material is at least 400 N / mm ² , the steel plate has a high yield point steel of 400 N / mm ² or more, and the thickness of the column material is reduced. Thus, the weight of the pillar can be reduced.
According to the configuration described in (6) above, for example, when a horizontal force is applied to the ground steel structure due to an earthquake or the like, the leg portion of the ground pillar can be rotated around its lower end portion. Therefore, it is possible to transmit the bending moment acting on the column base portion of the ground column during an earthquake or the like to the outer beam. Further, by allowing the outer beam to yield before the column base, the deformation of the ground column base can be kept within the range of elastic deformation. Therefore, plastic deformation of the column base portion of the ground column can be prevented.

It is a front view which shows the earthquake-resistant steel frame structure of the multilayer building which has an underground structure based on 1st Embodiment of this invention. It is sectional drawing of the 1st floor part of the building. It is an expanded sectional view of the pillar part of the building. It is sectional drawing which shows an example of arrangement | positioning of the damper provided in the building. It is a figure which shows the bending moment which acts on each part of a steel structure when a horizontal force acts on the building by an earthquake etc. It is a front view which shows the earthquake-resistant steel frame structure of the multilayer building which has an underground structure based on 2nd Embodiment of this invention. It is sectional drawing of the basement 1st floor part of the building. It is an enlarged front view which shows an example of the pin junction structure provided in the building. FIG. 8 is a cross-sectional view taken along the line AA of FIG. It is a figure which shows the bending moment which acts on each part of a steel structure when a horizontal force acts on the building by an earthquake etc. It is an enlarged front view which shows the modification of the pin junction structure in the 2nd Embodiment of this invention. FIG. 10B is a sectional view taken along line BB in FIG. 10A. It is a front view which shows the multilayer building which has the conventional underground structure. It is sectional drawing of the 1st floor part of the building. It is an expanded sectional view of the pillar part of the building. It is a top view which shows the connection structure of the 1st floor column base part and outer peripheral wall of the building. It is a figure which shows the bending moment which acts on each part of a steel structure when a horizontal force acts on the building by an earthquake etc.

Hereinafter, preferred embodiments of the present invention will be described.

(First embodiment)
Hereinafter, the earthquake-resistant steel structure according to the first embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a front view showing an earthquake-resistant steel frame structure of a multilayer building 4 having a subway frame structure 15. FIG. 2A is a cross-sectional view of the multi-layer building 4 cut horizontally in the vicinity of the first floor pillar. FIG. 2B is an enlarged cross-sectional view of the column portion of FIG. 1A. FIG. 3 is a plan view showing an arrangement state of the damper 3 in FIG. FIG. 4 is a front view showing bending moments acting on each part of the steel structure when a horizontal seismic force acts on the earthquake-resistant steel structure of the multi-layer building 4 during an earthquake.

The earthquake-resistant steel structure according to the present embodiment is used in the multi-storey building 4 having the ground steel structure and the subway structure 15.

As shown in FIG. 1, the subway frame structure 15 is designed to be wider than the ground steel structure. In the ground steel structure in the multi-layer building 4, an earthquake-resistant steel structure is formed by the plurality of pillars 1 (side pillars 1 a, corner pillars 1 b, and middle pillars 1 c) and the plurality of beams 2. Under the ground pillar 1, an underground pillar 1 d is provided.

The side pillar 1a, the corner pillar 1b, and the middle pillar 1c are provided at predetermined intervals. Side columns 1a and corner columns 1b, side columns 1a and middle columns 1c, and two side columns 1a are connected by beams 2.

The column 1 is a rectangular steel tube column, box-shaped cross-sectional column, circular steel tube column, H-shaped cross-sectional column, or cross-H cross-sectional column (which has a T-shaped cross section on the H-shaped cross-sectional column web). It may be constituted by a flanged cross-shaped cross-section column in which the legs of the steel material are fixed by welding. A diaphragm (an inner diaphragm, a through diaphragm, or an outer diaphragm) is provided at the beam joint portion of the column (not shown). The flange and web of the beam 2 are welded to this diaphragm. The diaphragm and the beam 2 may be joined via a splice plate (not shown). When the diaphragm and the column are welded, it is preferable to join them by complete penetration welding of a reshaped groove. For example, the column 1 is preferably a square steel pipe by cold forming with high toughness.

The subway skeleton structure 15 in the present embodiment includes an underground outer peripheral wall 5 formed in a closed ring shape by SRC or RC in the ground outside the side columns 1a and corner columns 1b on the ground. One end of an outer beam 2a that integrally supports the underground first floor ceiling slab 12 is connected to the underground outer peripheral wall 5. The other end of the outer beam 2a is connected to a column base 6 of a side column 1a on the ground or a corner column 1b on the ground. Between the column base 6 of the ground side column 1a, between the column base 6 of the ground side column 1a and the column base 6 of the corner column 1b, or the column base 6 of the ground side column 1a and the column base 6 of the middle column 1c. Are connected by a first-floor beam 2.
In the present embodiment, a damper 3 is provided on the outer beam 2a. As a specific example, between the outer outer beam structure 2b rigidly joined to the underground outer peripheral wall 5 and the inner outer beam structure 2c rigidly joined to the side column 1a or the corner column 1b, The outer beam 2 a is configured by joining the damper 3. As another example, the damper 3 is joined to the end of the outer beam 2a. You may comprise the damper 3 with the steel materials which have a yield point lower than the yield point of the outer beam 2a. Thereby, even if the cross-sectional shape of the damper 3 and the cross-sectional shape of the outer beam 2a are made substantially the same and both are joined in series, the role as the damper 3 can be achieved. Regarding the joining of the damper 3, an attachment portion may be provided on the damper 3 side, and the attachment portion on the pillar 1 or the underground outer peripheral wall portion 5 side may be joined by welding or bolts.
Since the damper 3 is a portion that is plastically deformed by a compressive force or tensile force in the beam axis direction, the position of the damper 3 in the beam axis direction may be any position in principle. As shown in FIG. 3, it is simpler and more economical to provide the underground outer peripheral wall.

As described above, by incorporating the damper 3 in the outer beam 2a, it is possible to introduce a portion that is more easily plastically deformed than the outer beam main body portion into the outer beam 2a. The damper 3 functions as a part of the outer beam 2a at all times, during a small earthquake, during a strong wind, etc., and when it receives a compressive force in the axial direction of the outer beam 2a during a large earthquake, the damper 3 does not buckle. It is plastically deformed by shrinking so that it does not occur, or plastically deformed by stretching when it receives a tensile force in the axial direction of the outer beam 2a. Accordingly, the joints between the column bases 6 of all the columns on the first floor (side columns 1a, corner columns 1b, and middle column 1c) and the upper portion of the underground column 1d and the first-level beam (outer beam 2a and other beams) 2 The joint part can be moved in the horizontal direction during an earthquake or the like.
In the form shown in FIG. 1, when one damper 3 in the left-right direction in the drawing receives a compressive force and plastically deforms, the other damper 3 receives a tensile force and plastically deforms, and the length of the outer beam 2a changes. As the position of the damper 3 incorporated in the outer beam 2a, it is preferable to arrange the damper 3 on the end portion side of the outer beam 2a on the underground outer peripheral side. As the material for the damper 3, for example, the low yield point steel used as the damping damper is used in order to cause plastic deformation and yield before the portion other than the damper portion of the outer beam 2 a. It is preferable. Further, the cross section perpendicular to the beam axis direction may be set smaller by design than the beam body side so as to be easily plastically deformed.

As described above, since the lower part (column base) of the ground pillar 1 is movable in the horizontal direction, as shown in FIG. It is possible to obtain a bending moment distribution similar to that of the beam-column joint of the second or higher floor without any shearing moment acting. And by securing the appropriate column beam strength ratio for the connection between the column base of the ground column 1 and the upper part of the underground column 1d and the beam 2 connecting the first floor outer beam 2a or the ground column base. The first-story beam 2 or the first-story outer beam 2a can be yielded prior to the ground column base 6 to prevent plastic deformation of the ground column base 6.

It is desirable to set the magnitude relationship of tensile strength as follows: damper steel <beam steel <column steel. For example, a steel plate having a tensile strength of 200 N / mm grade ² to 300 N / mm grade ² (design strength 80 N / mm grade ² to 205 N / mm grade ² ) is used for the damper 3, and the tensile strength is applied to the beam member or column member. Steel sheets of 400 N / mm class ² to 590 N / mm class ² (design strengths of 325 N / mm class ² to 440 N / mm class ² ) are used. Furthermore, a part of the axial direction (upper and lower flanges) of the beam is made smaller in cross section than the other parts, or a steel member having a low yield point is interposed at the junction between the column side flange and the beam. Thus, a portion that is easily plastically deformed is provided. Thereby, at the time of a big earthquake, the damper 3 (part of the low yield point steel) which is a part of the outer beam 2a can be plastically deformed in the beam axis direction. By this plastic deformation, the length of the beam in the axial direction can be expanded and contracted, and the one end side of the outer beam 2a and the joint portion of the first floor beam 2 together with the joint portion of the column base portion of the ground column 1 and the underground column 1d. Can be moved in the horizontal direction.

In addition, the ends of the first-floor beams 2 (outer side beams arranged between the side columns or between the side columns and the corner columns and other inner beams) other than the first-floor outer beams 2a are also illustrated. Although omitted, a portion to be plastically deformed may be added.

In this way, the reverse shear bending moment acting on the ground column 1 and the underground column 1d can be suppressed, and as shown in FIG. 4, the bending moment distribution changes to the same bending moment distribution as the column 1 in the second and higher floors. Can be made.
Therefore, even if a steel material with high yield ratio (high tensile steel) is used as the column material, it is possible to prevent the plastic deformation of the ground column 1 and to use the column within the elastic range, thereby reducing the column cross-sectional area. Therefore, it becomes possible to reduce the steel weight of the pillar, and the building can be constructed at a lower cost.

As a steel plate for column members, tensile strength of 490 N / mm grade ² to 590 N / mm grade ² or higher, 780 N / mm grade ² tensile strength (design strength (yield strength), 325 N / mm grade ² to 440 N / mm, respectively) ² grade to 700 N / mm grade ² ) can be used within the range in which the column is elastically deformed, but in the present invention, a steel material having a yield strength of at least 400 N / mm ² is used. It is good to do.
When adopting the technical idea to be used within the range of elastic deformation of columns, column members, especially side columns and corner columns, are pulled out when seismic energy such as horizontal force is input to the building at the time of earthquake The tensile force or the compressive force of indentation acts equally. However, the corner columns are further burdened by the pulling force and pushing force. For this reason, it is desired to increase the proof stress (or strength) of the corner column rather than the side column. As an appropriate design of the column beam strength ratio, it is preferable that the column beam strength ratio at the side column is 1.5 or more and the column beam strength ratio at the corner column is 1.7 or more.

However, when the hardening strengthening element related to the carbon equivalent or the like is increased in order to improve the tensile strength of the side column or the corner column, the weldability of the steel material is lowered. In addition, when different types of steel materials having different column material compositions are used, different treatments are required from the initial stage of the steel material production, which is not economical.
Because of these issues, in the case of a technology based on an elastic design that is used in the elastic range without plastically deforming the column, the yield strength can be reduced by heat treatment such as increasing the cooling rate without changing the composition of the column material. The one made higher (increasing the yield ratio) can be an inexpensive column material. In addition, since the burden when horizontal force is applied during an earthquake is different between the middle column, the side column, and the corner column, the middle column, the side column, and the corner column have the same steel composition and different performance. It is more reasonable to use steel because it can reduce construction costs.
In this way, when high yield point steel is used for the column to reduce construction costs, the increase in yield ratio and decrease in elongation at the high yield point may cause premature failure of the column. Although an earthquake-resistant steel structure is required, a rational earthquake-resistant steel structure can be obtained by adopting the structure of the first embodiment or the second embodiment described later.
The ground pillar of the multi-layer building 4 inevitably increases the load load, and thus its cross-sectional area increases. However, when the steel material has a high yield point as described above, the column cross-sectional area (plate thickness) is small (thin). In addition, an inexpensive column capable of reducing the steel weight without degrading the weldability of the column material can be used to provide a rational earthquake-resistant steel structure.

In the first embodiment, the ground column base 6 can be moved horizontally by providing the outer beam 2a with the damper 3 having the low yield point steel. However, the damper 3 may be in a form other than the above. Well, when a horizontal force is applied during a large earthquake, a similar effect can be obtained by incorporating a damper in a form that allows the outer beam 2a to expand and contract.
In addition, although illustration is abbreviate | omitted in the beams 2 other than the outer beam 2a, you may make it join the member of the pillar 1 side by incorporating a plastically deformable member, such as low yield point steel.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described in detail with reference to FIGS. In addition, the same reference number is attached | subjected to the member substantially the same as the member demonstrated in 1st Embodiment, and duplication description is abbreviate | omitted.
In the second embodiment described below, a pin connected structure is introduced below the column base 6 of the ground pillar 1. In other words, in the present embodiment, the bending moment acting on the column base is transmitted to the first floor beam by the pin joint structure. Thereby, generation | occurrence | production of the bending moment M3 of the reverse shear which acts on the ground column base 6 or the underground pillar 1d joined to this can be suppressed.

FIGS. 5 to 9 show an earthquake-resistant steel structure according to the second embodiment of the present invention.

FIG. 5 is a front view showing an earthquake-resistant steel frame structure of the multi-layer building 4 having the subway frame structure 15. FIG. 6 is a cross-sectional view cut horizontally in the vicinity of the upper part of the underground pillar in FIG. FIG. 7 shows an embodiment in which, when a horizontal force is applied to the multi-layered building 4, rotation is possible in all horizontal directions around the lower end of the ground column within the range of elastic deformation of the ground column. It is an enlarged front view. FIG. 8 is a cross-sectional view taken along the line AA in FIG. FIG. 9 is a diagram showing bending moments acting on each part of the steel structure when a horizontal force acts on the earthquake-resistant steel structure of the multilayer building 4 shown in FIG. 5 during an earthquake or the like.

In this embodiment, unlike the first embodiment, the damper 3 is not provided on the outer beam 2a. The outer beam 2a in this form is a beam similar to the inner beam 2, for example.

In addition, with regard to the connecting portion of the column base of the ground column 1 and the upper part of the underground SRC column 1d, for example, as shown in FIG. The column 1 may be provided with an inclined reduced cylindrical portion 14 that gradually decreases in a tapered shape. Thereby, the bending rigidity of the column 1 gradually decreases downward. By providing the reduced cylindrical portion 16 on the column 1, the lower part of the ground column base 6 can be rotated in all horizontal directions when a horizontal force acts on the column during an earthquake. That is, the pin joint structure 17 is realized by design.

In the illustrated embodiment, a receiving plate 18 is fixed to the lower inner side of the ground pillar 1. Moreover, the lower end part of the ground pillar 1 is inserted in the upper part of the underground pillar 1d, and is mounted on the support plate 7 of the underground pillar 1d. The lower end of the ground pillar 1 and the upper end of the underground pillar 1d may be joined by a bolt 8 such as a one-side bolt.
In the example of FIG. 7, one end of the first floor beam 2 or the outer beam 2 a is welded or bolted to a bracket provided on the ground column 1 at a position above the joint between the ground column 1 and the underground column 1 d. (In the case of illustration) It is joined. A steel plate (damper) such as a low yield point steel is interposed as a splicing plate 9 or the like at the joint between the ground column 1 and the first floor beam 2. A buckling restraining material 10 is disposed outside the attachment plate 9 at a predetermined interval in the beam axis direction. This buckling restraint material 10 is fixed by a high strength bolt 11. Further, by using a steel material having a lower yield point than the material of the column 1 as the steel material as the material of the beam 2, it is easy to realize the prior yielding of the beam.

As described above, the lower part of the column base of the ground column 1 is designed to have a pin joint structure, so that the bending moment acting on the column base of the ground column 1 can be changed to the ground beam (the outer beam 2, the inner beam 2 or the outer beam). Can be transmitted to the beam 2a) 2. Therefore, as in the case of the first embodiment, by securing an appropriate column beam strength ratio, the ground beam 2 is yielded ahead of the column base 6 so that the column base 6 is elastic. It becomes possible to hold in, and the plastic deformation of the ground column base 6 can be prevented. In addition, the bending moment distribution acting on the first floor beam 2 is a positive and negative symmetrical bending moment distribution, the bending moment distribution of one outer beam 2a is the bending moment distribution that becomes the maximum positive bending at the node on the ground column side, and the other outer The bending moment distribution of the beam 2a is a bending moment distribution that is the maximum negative bending at a node on the ground column side.

設計 The structure of the ground column base portion 6 to be a pin joint structure in design is not limited to the above form. For example, as a modified example, the base plate of the column base 6 of the ground column 1 is placed on the top plate at the upper end of the underground column 1d, and the ground column base is mounted by an anchor bolt or the like disposed at a position from the center of the underground column 1d. The sides may be fixed. Even in such a modification, when a horizontal force is input to the building during an earthquake, the lower part of the ground column base 6 can be rotated in all horizontal directions. That is, the pin joint structure 17 is realized by design. Then, by setting the column beam strength ratio as described above, it is possible to keep the column base within the elastic range by leading the first floor beam 2 ahead of the column 1 and yielding, so that the ground column Plastic deformation of the leg 6 can be prevented.

In the design, as the structure of the lower end of the ground column base 6 that becomes the pin joint structure, in addition to the above, as in the modification shown in FIGS. 10A and 10B, the lower end of the ground column 1 made of a square steel pipe column, A cross-shaped cross section at the upper end of the underground pillar 1d composed of a cross H-section pillar is inserted and joined by welding as appropriate, and at a position away from the joint with the ceiling beam 2 on the first basement floor, The lower side from the upper end may be embedded in a cylindrical steel pipe 19 filled with concrete. By reducing the rigidity of the lower end portion of the ground column base 6 and the upper end portion of the underground column 1d, the pin joint structure 17 can be obtained by making this portion rotatable in all horizontal directions. Thereby, the first floor beam 2 can be yielded earlier than the ground column base, and the plastic deformation of the ground column base 6 can be prevented, and the same effect as the embodiment shown in FIGS. 7 and 8 can be obtained. it can.

The steel structure may be realized by combining the pin joint structure described in the present embodiment and the damper described in the first embodiment. As a result, when a horizontal force acts on the building, the bending moment generated in the leg of the ground column is transmitted to the beam by the pin joint structure, and the force transmitted to the beam can be absorbed by the beam damper. .

In the case of carrying out the present invention, as a column of the first or higher floor, in addition to a square steel tube column or a box-shaped cross-sectional column, a steel material having a T-section in a web of a circular steel tube column, an H-shaped cross-sectional column or an H-shaped cross-sectional column It is good also as a cross-section column with a flange which fixed the leg part of this by welding. Moreover, as an underground outer peripheral part wall 5, an attachment part may be provided in the underground outer peripheral wall part which uses a steel sheet pile continuous wall as a core material, and you may make it connect to the outer beam 2a.

According to the present invention, it becomes possible to reduce the steel weight of a pillar, and a building can be constructed at a lower cost. Therefore, industrial applicability is great.

1 Ground pillar (or pillar of the second floor or higher)

1a side column

1b corner column 1c middle column 1d underground column 2 beam 2a outer beam 2b outer outer beam component 2c inner outer beam component 3 damper 4 multi-layered building 5 underground outer peripheral wall 6 column base 7 support plate 8 bolt 9 Bending plate 10 Buckling restraint material 11 High-strength bolt 12 Basement 1st floor ceiling slab (or 1st floor slab)
13 Square steel pipe column 14 Inclined reduced cylindrical part 15 Subway bone structure 16 Reduced cylindrical part 17 Pin joint structure 18 Base plate 19 Cylindrical steel pipe G Ground

Claims

A subway bone structure that supports a building having a ground pillar,
With the underground wall;
An underground column provided below a column base of the ground column;
An outer beam connecting the column base and the underground wall, the outer beam having a lower yield point than the column base;
Subway bone structure characterized by comprising.
The subway bone structure according to claim 1, wherein the outer beam includes a damper portion having a lower yield point than the outer beam.
The subway bone structure according to claim 2, wherein the damper portion is a steel material joined in series in the axial direction of the outer beam.
3. The subway bone structure according to claim 2, wherein the damper portion is a steel plate interposed between the outer beam and the ground pillar.
The steel structure according to claim 1, wherein the yield strength of the ground column and the underground column is at least 400 N / mm 2 .
The steel structure according to any one of claims 1 to 5, wherein the column base portion of the ground column and the underground column are joined by a pin joint structure.