JPH073886A - Earthquake resistant structure with braces - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a seismic resistant structure provided with braces having improved performance as a seismic resistant element, paying attention to the strength against the tension of braces arranged as diagonal members. [Structure] In order to increase the rigidity against the horizontal force that the frame of the steel structure 1 receives, the braces 4 are installed obliquely between the joints of the columns 2 and the beams 3 on each floor of the building 1, One fixed end was fixed to the shaft of the floor and the other fixed end was fixed to the shafts of the floors adjacent to each other vertically above and below the floor to form a truss for each floor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic structure of a building in which braces are provided between columns and beams of each layer of a steel frame structure, and particularly pays attention to the strength of braces arranged as diagonal members against tension. The present invention relates to a building having a seismic resistant structure provided with braces with improved performance as a seismic resistant element.

[0002]

2. Description of the Related Art A conventional high-rise building 1 having a steel frame structure is shown in FIG.
As shown in Fig. 4, a brace 4 is arranged on each floor between the joints of the frame formed by the columns 2 and the beams 3, and both ends of the brace 4 are fixed to form a diagonal member. To increase the rigidity of the building 1,
For example, between columns 2B-2C and 2E-2F, which are suitable for seismic design
The space is selected as a reinforced area, and a plurality of trusses are formed vertically. However, the brace 4, 4 ... on each floor is intended to improve the rigidity of its own floor, which was originally installed, and since it has a structure that enhances the rigidity of the entire high-rise building by improving the rigidity of each floor, the earthquake Due to the horizontal energy input received by the entire frame, no consideration is given to the fact that the horizontal force concentrates on a specific floor and induces buckling. It was included.

That is, the structure of each floor of the building is structurally analyzed for each layer, but the columns 2B, 2C, 2E of each layer,
Since the 2Fs are all continuous in the vertical direction, the force and moment are actually transmitted to the braces 4, 4 ... With respect to the horizontal force received by the frame. restoring force characteristics when a large earthquake, as shown in Table 1, the strength Q _B of the brace with respect to the displacement [delta],
The strength Q _R of the column and beam frames is plasticized, the proof stress is small, and the proof stress becomes zero when buckling, so not only the performance as a seismic resistant element decreases, but also to a specific floor due to buckling. In order to prevent damage to the building, it is necessary to increase the cross-sectional area of the brace 4 itself to increase the rigidity of each floor along with the reinforcement of the columns 2 and beams 3, which inevitably increases the cost of the earthquake-resistant frame. Met.

[Table 1]

[0004]

SUMMARY OF THE INVENTION The present invention was conceived in the process of reviewing the conventional braces from the viewpoint of energy absorption in view of the above situation and researching and developing a new function of the braces. The purpose is to
Damage to each floor due to horizontal energy input to the entire high-rise building is equalized as much as possible by the superposition structure of braces made of high-strength steel across multiple floors, and the damage is concentrated on a specific floor. In addition to being able to prevent, the brace itself only needs to bear the tensile force along with the equalization of the damage, and thus the cross-sectional area of the brace can be set small within the range of elastic deformation.
Therefore, it is intended to provide an excellent seismic structure having both economy and durability.

[0005]

In order to solve the problems, the first technical means adopted by the present invention is to construct a brace for a building in order to increase the rigidity against the horizontal force applied to the frame of the steel structure. When installing diagonally between the joints of columns and beams on each floor, fix one of the fixed ends of the brace to the shaft of the floor and the other fixed end of the brace on the floors adjacent to the floor above and below the floor. It is characterized in that a truss extending over a plurality of layers is formed on each floor while being fixed to a section, and as a second technical means, the brace is prepared from high-tensile steel. .

[0006]

Therefore, according to the present invention, the brace installed on the shaft portion of each floor over a plurality of floors cooperates with the pillars and beams of each floor as a truss in the form of an upper and lower superposition, so that the horizontal force applied to the frame is reduced. The rigidity of the entire building can be significantly increased, and the toughness of the middle layer is secured against the strength of the rigid frame at the top and bottom layers of the building when an external force such as seismic force is applied. It is possible to avoid concentration of damage to a specific layer, and to suppress the plasticization of columns and beams in each floor as much as possible, and improve the earthquake resistance of the building. be able to.

[0007]

EXAMPLE A seismic resistant structure provided with a brace of the present invention will be described with reference to the drawings of an example. In FIG. 1, reference numeral 1 is a building having a steel frame structure, 2 is a column vertically erected at positions A, B, C, ... Brace 4, 4, ... Made of high-strength steel as diagonal material is arranged in a cross shape between the joints of the columns 2 and beams 3. In the embodiment of the seismic resistant structure of the present invention, one fixed end 4a of the brace 4 arranged between the columns of BC in the drawing is fixed to the shaft portion of the floor and the other fixed end 4a.
b is fixed to the shafts of the floors that are separated by two floors in the vertical direction, and in the figure, as indicated by the thick line, it is inflected every two floors from the ground floor The floors are continuously slanted to the floor, and the braces 4 are not fixed to the beams and the crossing braces 4 and 4 are not joined at the crossing position at the intermediate position between the braces 4 and 4 ... At the same time, the columns 2, 2 ... And the beams 3, 3 ... On each floor form a truss extending over a plurality of layers by the braces 4, 4 ... .

Since the present invention is constructed as described above, the truss composed of the pillars 2, the beams 3 and the braces 4 forms a vertically overlapping structure over a plurality of ramen structures constituting each floor, and Even if the rigid frame structure of the frame is organically combined to give toughness to the frame itself and the horizontal force concentrates on a specific floor with respect to the horizontal force received by the frame, a plurality of frames located above and below the specific floor The rigid frame structure cooperates with the rigid frame structure of the floor via the truss to avoid concentration of damage on a specific floor and increase the rigidity of the entire high-rise building. Therefore, the damage due to the horizontal force applied to the frame is not concentrated on a specific floor, and the plasticization of the columns 2 and the beams 3 of each floor can be suppressed as small as possible.

Here, description will be made based on Tables 3, 4, 5, and 6. Tables 3 to 6 above show an ideal model that has optimum structural specifications without braces and that is difficult to realize, and the seismic resistant structure (stiffness ratio of braces = 0.1) of the present invention is used for this ideal model. For the actual building of 20 layers, the energy absorption rate (= Wpi / Wp), the average cumulative plastic deformation ratio η, the maximum interlayer deformation δ, and the apparent plastic deformation ratio μ are set without braces using the El Centro NS wave as the input seismic wave. The measurement is made under each condition of / and the result is shown in a line graph.

[Table 3]

[Table 4]

[Table 5]

[Table 6] In each of the line graphs in Tables 3 to 6 above, the average cumulative plastic deformation ratio η and the apparent plastic deformation ratio μ are
The flattening and reduction of the deformation ratio in the middle layer was recognized as compared with the case without braces, and the maximum interlayer deformation δ and energy absorption rate were smaller among the layers as compared with without braces. However, the damage dispersion effect of the entire frame is recognized. That is, each broken line with braces (stiffness ratio = 0.1) is relatively flatter than the broken line without braces, which means that the frame structure is more sensitive to the horizontal energy input received at each floor. While the equalization of the response on the side is achieved, it is shown that damage is likely to be concentrated between the floors without braces where the polygonal line changes sharply, and the response to the horizontal energy input is equalized. Shows the substantial and remarkable effect of the earthquake-resistant structure of the present invention.

On the bottom floor (first floor) of each table, the response of each broken line with braces (stiffness ratio = 0.1) is larger than that without braces. This is because the overlapping structure is configured for the upper floors on and after the second floor, and it is possible to easily supplement it by providing an energy absorbing member separately on the lowermost floor or increasing the strength of the lowermost floor. It is possible.

Further, since the braces 4, 4, ... Are made of high-strength steel, the building 1 adopting a seismic structure is used.
For the restoring force characteristic when the earthquake, as shown in Table 2, column, although the intensity Q _R of the beam of noodles pursuant to Q _R in Table 1, the intensity Q _B braces act elastically Plasticity does not appear. For example, the rigidity S ₁ of the rigid frame structure of the building ₁ and the rigidity S _{2 of the} braces 4 and 4 are defined as follows, and S ₁ = (12 · E · I / h ³ ) × n E: Young's modulus S ₂ = (E · A / h) × cos θ I: Column moment of inertia h: Floor height n: Number of columns in the floor A: Brace cross-sectional area θ: Brace slope angle Above S ₁ , When the rigidity ratio of S ₂ is 0.1, the required cross-sectional area A of the braces 4 and 4 is about 1/200 of the cross-sectional area of the column.

[Table 2] Therefore, the braces 4, 4, ..., themselves are always elastic and only need to retain the property of bearing only the tensile force, and it is possible to adopt a flat bar or steel wire having a relatively small cross-sectional area. Becomes

Further, FIG. 2 shows another embodiment in which the braces 4 arranged between the columns of the BC have fixed ends between the shaft portions of the floors which are vertically separated by three floors. The thing
In this example, it is needless to say that the superposition of the braces 4, 4, ... Is more densely configured and the seismic effect is further increased.

[0013]

In summary, according to the present invention, in order to increase the rigidity with respect to the horizontal force applied to the frame of a steel frame building,
To install a brace diagonally between the joints of columns and beams on each floor of a building, fix one fixed end of the brace to the shaft of your floor and adjoin the other fixed end above and below your floor. It is fixed to the shafts of the alternate floors to form trusses that span multiple floors for each floor.Because the braces are made of high-strength steel, the horizontal energy input received by the entire high-rise building causes The layered structure of braces made of high-strength steel that spans multiple floors makes it possible to equalize damage as much as possible and prevent damage from concentrating on specific floors. When the external force of the building is received, the toughness of the middle layer is secured against the proof strength of the rigid frame at the top and bottom layers of the building, and the pillars and beams at each level can be plasticized as much as possible. It is possible to suppress it, improve the earthquake resistance of the building, and With the equalization of the brace, the brace itself only needs to bear the tensile force, so the cross-sectional area of the brace can be set small within the range of elastic deformation, thus achieving both economy and durability. It has an extremely useful new effect of being able to

[0014]

[Brief description of drawings]

FIG. 1 is a framed elevational view of a building illustrating braces arranged in every two layers.

FIG. 2 is a framed elevation view of a building illustrating braces arranged in every three layers.

FIG. 3 is a frame elevation view of a conventional building for explaining braces arranged on each floor.

[Explanation of symbols]

 1 Building 2 Pillar 3 Beam 4 Brace

Claims (2)

[Claims] 1. A fixed end of one of the braces is provided so that the brace is obliquely installed between the joints of columns and beams on each floor of the building in order to increase rigidity against horizontal force applied to the frame of the steel structure. Is fixed to the shaft of its own floor, and the other fixed end is fixed to the shafts of the alternate floors that are vertically adjacent to the floor of the own floor, forming trusses for a plurality of levels for each floor. Earthquake resistant structure with braces. 2. The seismic resistant structure with braces according to claim 1, wherein the braces are made of high-strength steel.