JPH0733685B2 - Brace type flexible mixed structure with seismic energy absorption function - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brace-type flexible / rigid mixed structure provided between beams of a building structure, etc., and particularly, energy from an external force is generated by its plastic deformation. The present invention relates to a brace type flexible rigid structure having a seismic energy absorbing function such as absorbing.

“Conventional technology and its problems” Conventionally, a brace structure provided as a reinforcing element of a building structure has high rigidity for exerting an original reinforcing function, and of course, an axial force generated against an external force such as an earthquake. Sufficient toughness that does not buckle due to bending moment is also required.

By the way, although steel frames are mainly used for the brace of the brace structure, in such a brace structure, there is a possibility that the buckling of the brace particularly at the time of compression may cause a sharp decrease in the proof strength. In addition, provisions such as an increase in design stress and an increase in structural characteristic coefficient are provided, and so-called proof-strength-oriented measures are taken to absorb seismic energy by increasing brace proof stress. However, such a brace structure inevitably causes an increase in member cross section and an increase in member weight because the brace material is increased by the stress increase, which results in a high material cost and a poor structural balance. He left behind problems to be solved such as balance.

In recent years, with respect to the external force of the scale such as the largest earthquake that is expected to occur within the service life of a building structure, to the extent that the building structure does not collapse, some of the members of this building structure The idea of allowing plastic deformation to absorb the energy of the external force has been accepted, and a design method called a final design method aiming at so-called plasticization is actually being applied.

This invention applies the concept of the ultimate design method to the design of a brace structure, and it is possible to improve the energy absorption capacity of the entire building structure without increasing the yield strength of the members constituting the brace structure. The question is how to realize a brace type flexible mixed structure with seismic energy absorption function.

"Means for solving problems" The present inventors, as a result of earnest research in view of the above problems,
The following findings have been obtained.

That is, according to the seismic limit design method based on the energy theory that evaluates the load effect due to an earthquake as energy,
The optimum strength (yield layer shear force) distribution of each layer of the building, in other words, the yield layer shear force coefficient distribution i in the i-th layer, can be uniquely obtained and is given by the following equation (Hiro Akiyama, "Architecture Seismic limit design of objects "(University of Tokyo Press).

f (x) = 1 + 1.5927x -11.8519x 2 + 42.5833x 3 -59.4827x 4 + 30.1586x 5 The strength αi of a layer is less than this optimum distribution i, the external force caused by an earthquake or the like in this layer Energy will be concentrated. On the contrary, if this principle is used, by appropriately adjusting the strength αi of each layer, the energy of the external force can be distributed to each layer at a desired ratio, and for example, only the strength of the first layer of the building can be reduced. By making this first
External force energy can be concentrated on the layer. further,
If the external force energy concentrated in the first layer is absorbed by the plastic deformation of the members of the first layer according to the above-mentioned ultimate design method, the external force energy transmitted to the second layer and above can be reduced, and therefore, the construction It can provide seismic isolation effect to the whole thing.

According to the findings shown above, the present invention is applied to a region surrounded by horizontal members such as beams and vertical members such as columns, which is a part of the frame of a building structure, and has a function of absorbing vibration energy during an earthquake. A brace type flexible rigid structure, wherein an energy absorbing member for absorbing vibration energy is installed in the region, and the energy absorbing member and the frame are connected to each other to reduce the vibration energy at the time of the earthquake. A brace for transmitting from the skeleton to the energy absorbing member is provided, and both the vertical member and the brace are formed as elastic members that can be deformed within an elastic deformation limit during an earthquake of an expected scale, while the energy absorbing member is , As a plasticizing member that is relatively less elastic than the vertical member and the brace and that yields and plastically deforms during the earthquake. It is characterized in that by comprising.

"Operation" The flexible-stiff mixed structure of the present invention is an elastic member that only elastically deforms even during the extreme maximum earthquake expected to occur during the service life of a building structure, and at that time yields. It is also used in combination with a plasticizing member that plastically deforms due to the deformation.

That is, in the building structure adopting the flexible rigid structure of the present invention, the vertical members such as columns and the braces are deformed within the elastic deformation limit even at the time of the largest scale earthquake by using a highly elastic material such as high tensile steel. Elastic member (that is, flexible member)
On the other hand, the energy absorbing member is made of a material such as ordinary steel, which is relatively less elastic than high-strength steel, and is a plasticizing member that yields and plastically deforms during the largest earthquake ( That is, it is formed as a rigid member.

Therefore, in this structure, the vibration energy is absorbed as plastic strain energy by the plastic deformation of the energy absorbing member at the time of the largest earthquake, and the vertical member and the brace are not elastically deformed. Control the amount and residual deformation within the allowable limit.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a brace type flexible / rigid mixed structure (hereinafter, simply referred to as “brace structure”) having an earthquake energy absorbing function according to the first embodiment of the present invention,
The brace structure B is provided on the first layer F of the building A as shown in FIG. In FIGS. 1 and 2, a building A constructed on a ground G is a building having a so-called steel structure, and a column (vertical member) 1 as an elastic member made of a high-strength steel rectangular steel pipe, .. and beams (horizontal members) 2, 2, ... Made of H-shaped steel form the skeleton thereof. In the first layer F of the building A, the pillar 1 is formed in the small diameter portion 1a whose diameter is reduced.

In the building A, the energy absorbing members 4, 4 (in the following, the plasticizing member 4, 4 as a plasticizing member made of a rectangular steel pipe made of ordinary steel having a lower elasticity than the pillar 1 in the first layer F thereof are included in the building A. 4) is provided. The plasticizing members 4 and 4 are
Two columns are erected on the ground G so as to be located between the columns 1 and 1. The upper ends of the plasticizing members 4 and 4 are connected by a connecting member 5 made of H-shaped steel. From this plasticizing member 4, a brace 3 as an elastic member made of a steel pipe made of ordinary steel or high-strength steel is provided through a mounting plate 7 toward an intersection (joint) C between the pillar 1 and the beam 2. Be extended,
The brace 3 is attached to the beam 2 at the intersection C by a gusset plate 8.

Then, each member as an elastic member constituting the building A, that is, the rectangular steel pipe forming the pillar 1, the H-shaped steel forming the beam 2, and the steel pipe forming the brace 3 are , Both of them will only elastically deform even during the extreme maximum earthquake expected to occur during the service life of this building A (the stress generated at that time is within the allowable stress level), Although its material and cross-sectional shape are determined, the plasticizing member (energy absorbing member) 4 provided in the first layer F of this building A yields and plastically deforms during such an earthquake of maximum magnitude. The material and cross-sectional shape are determined so that Here, the plasticizing member 4
Is a short column type member having a short length, so that the slenderness ratio is small, and therefore, the reduction in proof stress due to buckling is suppressed, and by designing the width-thickness ratio to be small, harmful twisting,
It is possible to prevent local deformation from occurring, which makes it possible to secure a large plastic deformation capacity of the plasticizing part member 4 itself.

In the building A provided with the brace structure B as described above,
At the time of a normal-scale earthquake, which is expected to occur several times during the service life of the building A, all of the columns 1, the beams 2, the braces 3, and the plasticizing members 4 will behave within the elastic range in the restoring force characteristics. Further, when an external force of the largest earthquake scale expected to occur during the service life of the building A is applied, the energy of the external force is transmitted to the plasticizing members 4 and 4 via the brace 3. Then, the plasticizing members 4 and 4 yield.
As a result, most of the energy of the external force is in the first layer F.
By being absorbed as plastic strain energy in, the energy transmitted to the layers above this is reduced, and therefore, the seismic resistance effect on the entire building structure can be obtained. Therefore,
Unlike the conventional method, in which the seismic effect is obtained by increasing the yield strength of the members forming the brace structure B, the plasticizing member 4
Since the energy of the external force is absorbed by the plastic deformation ability of the brace structure B, the brace structure B capable of obtaining the seismic energy absorption effect without increasing the proof stress of the members forming the brace structure B, especially the brace 3 itself is realized. It becomes possible. As a result, as described above, the problems of the increase of the member surface, the increase of the material cost due to the increase of the member weight, and the imbalance of the structural balance are solved.

Further, as described above, the pillar 1, the beam 2, and the brace 3 are provided.
Each has its own large elastic deformation capacity, and by maintaining an elastic state even against an external force of the largest earthquake scale, the maximum deformation of the entire energy concentration layer (first layer F),
It has the effect of suppressing an increase in residual deformation. It also has a function of preventing the building A from deteriorating due to the P-?

In particular, in this embodiment, since the pillar 1 has a reduced diameter in the portion where the brace structure B is provided, that is, in the first layer F, the strength of the first layer F and the portions of the other layers are reduced. When a force such as an earthquake is applied to the building A, energy from the force is concentrated on the first layer F of the building A. Therefore, it becomes easy to accurately grasp the energy absorption amount, and it is not necessary to consider the plastic deformation over all layers as in the above-mentioned conventional ultimate design method. The degree of freedom in designing is increased. Further, as described above, in the layers other than the first layer F, the energy transmission of the external force is reduced, so that it is not necessary to secure a large rigidity of the constituent members, and thus it is possible to reduce the weight of the members such as the steel frame. Become.

In addition, in the brace structure B, when a horizontal force such as an earthquake is applied, the shearing force generated in the connecting member 5 and the vertical component of the axial force generated in the braces 3 and 3 cancel each other in the opposite direction. The excellent effect that the axial force acting on the plasticizing members 4 and 4 is reduced to an almost negligible level is achieved. Similarly, by appropriately adjusting the rigidity of the connecting member 5 that connects the plasticizing members 4, 4, the plasticizing members 4,
There is also an advantage that the moment distributions acting on both ends of 4 can be made as uniform as possible, and thereby the energy absorbing capacity of the plasticizing members 4 and 4 can be increased.

Here, an optimal combination of the physical property values of the column 1 as the elastic member and the plasticizing member 4 will be described. The combination of these physical property values changes depending on the floor height of the building and the level setting of the maximum earthquake that can be endured by the strain energy absorption capacity of the plasticizing member 4 and the earthquake that keeps it elastic. Therefore, the combination given by the following equation is most preferable. .

sQy / hQy ≧ 1/3 sδy / hδy ≧ 3.0 h / h ≧ 0.35 hQy: Sum of yield shear forces of plasticizing members of the layer sQy: Sum of yield shear forces of elastic members of the layer hδy: of plasticizing members Yield deformation amount sδy: Yield deformation amount of elastic member h: Average apparent plastic deformation ratio h: Average cumulative plastic deformation ratio That is, in the graph shown in FIG. 5, yield shear force sQy of elastic member and yield deformation It suffices if the amount sδy is a region surrounded by diagonal lines. The dimensions of the members 4 and 5 are determined irrespective of the floor height and the column span, and the physical property values can be easily obtained by changing the number of arranging structural surfaces of the members 4 and 5, the member length, and the cross-sectional dimension. In the figure, Kp.d represents a spring for canceling the P-δ effect.

Next, FIG. 3 is a view showing a brace structure B which is a second embodiment of the present invention. In the following description, the same components as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. The difference between the brace structure B of the second embodiment and the brace structure of the first embodiment is that only one plasticizing member 4 is erected between the columns 1 and 1. Also, with the brace structure B according to the second embodiment, it is possible to obtain the same effect as that of the brace structure according to the first embodiment.

Further, FIGS. 4 (a) to 4 (j) are views showing a brace structure B which is another embodiment of the present invention. In addition, in FIG. 4 as a whole, reference numeral 10 indicates a pin joint point,
Further, in FIGS. 4 (b) to (c), reference numeral 11 is a connecting member made of H-shaped steel, and in FIG. 4 (j), reference numeral 12 is a steel plate made of ordinary steel. With the embodiment shown in FIG. 4 as well, it is possible to obtain the same effect as the brace structure of the first embodiment.

The brace structure B of the present invention is not limited to the above embodiment. For example, the brace structure B may be provided not only in the first layer F but also in any layer, or may be provided in a plurality of layers. Further, the material and cross-sectional shape of the elastic member pillar 1 and the plasticizing member 4 are not limited to those of the embodiment, and may be appropriately selected from well-known materials and cross-sectional shapes according to the combination of the physical property values described above. Just go. Further, the yield time of the plasticizing member 4 may be set not only for the external force of the largest earthquake scale but also for the smaller external force, as in the above-mentioned embodiment, In short, it may be appropriately selected depending on how much external force is expected to have a significant seismic effect. Further, although the brace structure B is applied to the building A having a steel frame structure in the above-described embodiment, it is also applicable to a reinforced concrete structure and a steel frame reinforced concrete structure.

"Effects of the Invention" As described in detail above, the structure of the present invention provides an energy absorbing member in a region surrounded by a vertical member and a horizontal member that constitute a framework of a building structure, and the energy absorbing member is provided. Brace for transmitting vibration energy at the time of earthquake, and the vertical member and brace are formed as elastic members that stop deforming within the elastic deformation limit even at the time of an earthquake of a certain scale, while absorbing energy. Since the member was formed as a plasticizing member that yields and plastically deforms during the assumed earthquake, for example, the energy absorbing member will be used during the extreme maximum earthquake expected to occur within the service life of this building structure. The plastic deformability of the structural member is set by setting the vertical member and the brace so that they yield and plastically deform, and the vertical member and brace stop elastic deformation. A brace type flexible rigid structure is realized as an effective seismic isolation structure based on the ultimate design method using force.

Further, according to the structure of the present invention, the problem that the member cross section and the weight of the brace increase unnecessarily as in the case of the conventional general seismic structure of improving the seismic performance by increasing the proof stress of the brace is solved. It In addition, vertical members such as columns and braces, which are other structural members of this building structure, will only elastically deform even during the earthquake of the above-mentioned scale, so the energy absorbing member (plasticizing member) will yield and become plastic. Even if it is deformed, it is possible to suppress the maximum deformation amount and residual deformation amount of the entire building structure within the allowable limits, so even in the event of the largest earthquake, the entire building structure can be destroyed or seriously damaged. Can be avoided.

[Brief description of drawings]

FIG. 1 is a front view showing a brace type flexible-stiff mixed structure having an earthquake energy absorbing function according to a first embodiment of the present invention, and FIG. 2 shows a building provided with the flexible-stiff mixed structure. Front view, FIG. 3 is a front view showing a brace type flexible / rigid mixed structure having a seismic energy absorbing function according to the second embodiment of the present invention, and FIG. 4 is an earthquake according to another embodiment of the present invention. FIG. 5 is a schematic view showing a brace type flexible-mixed structure having an energy absorbing function, and FIG. 5 is a view showing a combination of yield shear force and yield deformation amount. A: Building (building structure), B: Brace structure (brace type flexible structure), C: Crossover part, F:
First layer (region) 1 ... Pillar (vertical member and elastic member), 2 ... Beam (horizontal member), 3 ... Brace (elastic member), 4 ... Plasticizing member (energy absorbing member).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Ikura 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (72) Shinji Mase 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction company (72) Inventor Toshihiko Hirama 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction company Inspector Satoshi Aoyama

Claims (1)

[Claims] 1. A brace-type of a structure that is applied to a region surrounded by horizontal members such as beams and vertical members such as columns, which is a part of the skeleton of a building structure, and has a function of absorbing vibration energy during an earthquake. The structure is a flexible mixture, and an energy absorbing member that absorbs vibration energy is installed in the region, and the energy absorbing member and the frame are connected to absorb the vibration energy during an earthquake from the frame. A brace that transmits to a member is provided, and both the vertical member and the brace are formed as elastic members that can be deformed within an elastic deformation limit during an earthquake of an expected scale, while the energy absorbing member and the vertical member and Characterized in that it is formed as a plasticizing member that is relatively less elastic than the brace and that yields and plastically deforms during the earthquake. Brace with a seismic energy absorption function that
Type of flexible rigid structure.