JP4700817B2 - Seismic control frame - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a seismic control frame designed to reduce the vibration response of a structure during an earthquake or a strong wind.
[0002]
[Prior art]
Various damping devices such as oil dampers, viscoelastic dampers, steel dampers and friction dampers have been developed and put into practical use as means for reducing the vibration response of structures during earthquakes and strong winds. Various types of vibration control frames are also known in which a damping device as described above (hereinafter sometimes simply referred to as a damper) is attached to reduce the vibration response of the structure. However, even if an attenuation device of the same capacity is installed, the damping effect (attenuation effect that suppresses the shaking) that the attenuation device gives to the frame or structure depends on the mechanical properties or conditions of the installation location. It is already well known to those skilled in the art. In general, it is understood that the installation and installation of a damping device in a place where the amount of deformation and force applied to the damping device are large is an efficient use and arrangement of the damping device. For example,
[0003]
A. The seismic control frame disclosed in Japanese Patent Application Laid-Open No. 2000-27294 is a semi-rigid joint that is close to a pin joint with a lower rigidity than a normal rigid joint. Are concentrated on the damping device to improve the efficiency of the damping action (seismic energy absorption action).
[0004]
B. The vibration control frame disclosed in Japanese Patent Application Laid-Open No. 11-50688 has two types of structures having different vibration properties (for example, a core portion located in the center of a horizontal section of a building and a living portion located on the outer periphery thereof). This is a so-called coupled vibration control structure in which a general frame part) is connected to an expansion joint and a damping device.
[0005]
[Problems to be solved by the invention]
In the case of the above-mentioned seismic control frame A, the invention is devised so that the damping device works efficiently on one frame surface (flexible surface) of the main frame in the structure, and the invention considering the vibration characteristics of the entire structure is not. Accordingly, there is room for further optimization of the vibration characteristics of the entire structure.
[0006]
On the other hand, the above-mentioned vibration-damping building B is recognized as an invention in consideration of the vibration characteristics of the entire structure, but there are many restrictions on the rigidity, mass, and arrangement of the frame, and the buildings that can implement this invention are limited.
[0007]
By the way, in general, torsional vibration is undesirable for a structure, and structural designers strive to design in consideration of the balance of mass and rigidity of the structure so that torsional vibration does not occur. However, if no torsional vibration occurs in the structure, the amount of deformation generated in each layer of the structure is constant regardless of the location for each layer, and it is not possible to optimize the arrangement of the damping device to a certain extent. Enveloping the problem.
[0008]
The object of the present invention is to reverse the common sense that torsional vibration is generally undesirable for a structure, and as a concept of reverse rotation, it is designed in a frame type that intentionally generates torsional vibration. Is to provide a seismic control frame that has been improved so that torsional vibration of the structure does not occur as a result.
[0009]
The next object of the present invention is to cause the structure to twist and vibrate when the structure is vibrated in the horizontal direction, thereby concentrating the deformation on the specific frame surface where the attenuation device is installed. The aim is to provide a seismic control frame that is devised to maximize its effects.
[0010]
As a means for solving the above-mentioned problem, a seismic control frame according to the invention described in claim 1 is:
It is a seismic control frame that attaches a damping device to reduce the vibration response of the structure,
The frame of the structure is designed so that the stiffness and the center of gravity are decentered by breaking the balance of the rigidity of the structure or the mass of the structure so as to generate a torsional vibration in response to horizontal excitation.
The construction surface closer to the center of gravity than the center of gravity is defined as a rigid construction surface, and is disposed facing the rigid construction surface, and the construction surface on the side farther from the stiffness than the rigid construction surface is defined as a flexible surface. The damping device is characterized in that damping devices are more concentratedly installed on the flexible surface than on the rigid surface .
[0011]
The invention according to claim 2 is the seismic control frame according to claim 1, wherein the mass of the structure is uniform and the rigid element faces only when there is a rigid element only on the outer circumference of the structure. It is characterized by being designed so that the rigidity ratio between the soft surface and the flexible surface is 2: 1.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, illustrated embodiments of the present invention will be described.
[0013]
FIG. 1 shows a first embodiment of a vibration control frame according to the first aspect of the present invention. This is an embodiment in which the present invention is applied only in one direction (vibration direction = Y direction) for the structure 1 having two planes for the sake of simplicity. That is, the direction (vibration direction) in which damping is considered is only the Y direction (one direction) indicated in FIG. Of the two planes located at both ends in the X direction, one plane is a relatively rigid plane closer to the center of gravity than the center of gravity (hereinafter referred to as rigid plane A). In the case of 1, the brace 2 is used to increase the rigidity. The other structural surface is arranged to face the rigid structural surface A, and is a relatively soft structural surface on the side farther from the rigid center than the rigid structural surface A (hereinafter referred to as a flexible structural surface B). In the case of FIG. 1, the frame structure has no brace.
[0014]
When there is no bias in the mass distribution of the structure 1, the rigidity ratio between the rigid surface A and the flexible surface B in FIG. When the structure 1 is vibrated in the vibration direction (Y direction), when viewed in plan, the torsional vibration as shown in FIGS. 2a, 2b, and 2c occurs, and the flexible surface B is far from the center of the twist. Is larger than the rigid structural surface A.
[0015]
Therefore, by installing the damping device (damper) 3 intensively on the flexible surface B, it is said that the damping device 3 is effectively utilized by utilizing the property that the vibration of the flexible surface B is relatively large. This is the gist of the present invention. 1 and 2c schematically show the application of the brace-type damper 3. FIG.
[0016]
Of course, the implementation of the present invention is not limited to application to a frame that only vibrates in two planes and one direction as shown in FIG. The same position as the case of the rigidity ratio of 2: 1 (see FIG. 11a), which is a guideline in the case of the two structural surfaces described above (see FIG. 11a), the building width of 1 from the rigid structural surface A side toward the flexible structural surface B side. It is only necessary to design the rigidity of each structural surface so that the position of / 3 = see FIG. 11b). However, the reference position of the stiffness ratio described above is a value when it is assumed that there is no bias in the mass distribution of the structure 1. When there is a bias in mass, each structural surface may be designed so as to produce the same degree of eccentricity (deviation of the center of gravity and stiffness). For example, when the position of the center of gravity is at a position 2/3 of the building width toward the rigid structure surface, the rigidity of the rigid structure surface and the flexible surface may be approximately the same (1: 1).
[0017]
In short, it is not necessary to apply in two directions. However, in the case of applying in two directions, the same design may be performed for each direction, and the present invention can be implemented in exactly the same manner.
[0018]
3 and 5 show the second and third embodiments of the present invention. These embodiments are examples when the present invention is applied to a frame that twists and vibrates in two horizontal directions, and has a rigid surface A and a flexible surface B at both ends in the long side direction (X direction). Is common to the example of FIG. However, the brace 2 and the damper 3 are installed in all layers of the structure 1, but this is not the case. It can also be implemented only in the main layer. The characteristic configuration in FIG. 3 is that as a means for giving a difference in rigidity between both long side surfaces (corresponding to the front side and the back side in FIG. The construction method of designing the construction surface and attaching the damper 5 to the flexible construction surface is the same as the embodiment of FIG. FIG. 4a shows a state where the structure 1 of FIG. 3 vibrates in the short side direction (Y direction), and FIG. 4b shows a case where the structure 1 vibrates in the long side direction.
[0019]
The embodiment of the seismic control frame shown in FIG. 5 has three structural surfaces A, B, and C in the short side direction, and the intermediate structural surface C is moved to the left (close to the rigid structural surface A) in the figure, so-called The rigid center position is on the left side, and twisting and vibration are the same as in FIGS. 4a and 4b. In the case of FIG. 5, as a means for giving a difference in rigidity between both long-side structural surfaces (front side and back side), the column beam joint 6 (circled portion) is semi-rigidly joined (or pin joined). Designed as a soft surface. And the point which has attached the brace-type damper 7 is the same as the basic composition of FIG. Normally, the seismic frame is rigidly joined (including semi-rigid joints that can be regarded as a method), but if semi-rigid joints are sufficient as described above, there is a great merit in reducing the cost of joining.
[0020]
Next, the embodiment of the seismic control frame shown in FIG. 6 shows an example in which the mass of the structure 1 is biased to generate torsional vibration. In the case of FIG. 6, the height is increased only in the left portion D in the figure, and the position of the center of gravity is biased to the left. As a result, a torsional vibration as shown in FIG. 7 is generated. The brace-type damper 3 is also installed on the flexible surface B having a large amplitude (the surface far from the twist center) as in the example of FIG.
[0021]
In addition, the design of the rigid surface A and the flexible surface B can be realized by a method of giving a difference in rigidity by adjusting the cross section of the member, or a difference in rigidity can be caused by a difference in structure type. Is possible. For example, when the rigid surface is a rigidly bonded ramen structure, the flexible surface is a semi-rigidly bonded ramen structure, or the rigid surface is a brace structure and the flexible surface is a rigidly bonded ramen structure without braces. In addition to this, it is possible to cope with such a design as “providing a wall on the rigid structure side with an RC structure”.
[0022]
Further, regarding the structure type and type of the dampers 3 and 7, oil dampers, viscoelastic dampers, steel dampers, friction dampers, and the like can be used as appropriate. In particular, since steel dampers and friction dampers have different characteristics before and after yielding (or slipping), for example, the rigidity ratio between the rigid and flexible surfaces before yielding is set to the same 1: 1, yielding. If it is designed to have a rigidity of 2: 1 later, it can be implemented as a seismic control frame that vibrates without twisting during a small earthquake and twists during a large earthquake to exert a damping effect.
[0023]
Next, in order to show the effect of this invention, the result of having performed the parameter study on the structure of one mass point is demonstrated.
[0024]
First, as a structure model, consider a one-mass-point two-component building shown in FIG. The horizontal rigidity of the hierarchy is constant, and the ratio between the rigidity of the rigid structural surface A and the rigidity of the flexible structural surface B shown in FIG. 8 is defined using r: 1-r and the parameter r. Additional dampers were arranged at a ratio of q: 1-q on each frame in the frame of FIG. 8, and the transmission characteristics (ratio of response acceleration to input acceleration at each frequency) were examined. The total damping coefficient of the additional damper is normalized so that the natural frequency of the model is 1 at r = 0.5. The maximum value of the transfer function for each value of the parameters r and q is plotted in FIG. In the case of torsional vibration, since the response differs depending on the location of the mass point, the maximum value is the larger of the response values at both ends.
[0025]
According to FIG. 9, it can be seen that the maximum value of the transfer function is minimized when r = 0.7 and q = 0. That is, Tsuyoshi Plane rigidity: stiffness of soft Plane = 0.7: 0.3 ≒ 2: 1 and then, it can be seen that all the dampers is best to attach the soft Plane side. At this time, the maximum value of the transfer function is reduced to about 75%.
[0026]
The transfer function is shown in FIG. 10 in comparison with the case of r = 0.5 and q = 0.5 (conventional design method in which rigidity and damping are arranged in a balanced manner).
[0027]
In the case of the conventional design method, since it is designed so as not to cause twisting, there is no difference in response depending on the location of the mass point in the analysis. On the other hand, in the case of the design method according to the present invention, since there is a difference in response depending on the location of the mass point, the response values at three locations of “soft surface” and “rigid surface” and “center” of the structure are shown As shown in the figure, there is a difference in response depending on the twist generated in the frame. The response value of the “flexible surface” is the largest, but it is still smaller than the response value in the conventional design method, and the response is further reduced at the “center” position and “rigid surface” position of the structure I understand that.
[0028]
It can be seen that by designing the structure so that it can be twisted and arranging the dampers in a concentrated manner, even with the same amount of dampers, the response is reduced, that is, the dampers are used efficiently. .
[0029]
【The invention's effect】
The invention described in claims 1 and 2 overturns the common sense that it is not desirable for a structure, and as a concept of reversal, after deliberately designing a frame type that generates torsional vibrations, the effects of the damping device are As a result of the optimization, a seismic control frame in which vibration of the structure including torsional vibration is reduced is provided.
[0030]
In the present invention, when the structure is vibrated in the horizontal direction, the structure causes torsional vibration, so that the deformation is concentrated on a specific frame surface on which the attenuation device is installed, and the effect of the attenuation device is reduced. We will provide a seismic control frame that can be used to the maximum extent possible.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of a seismic control frame according to the inventions of claims 1 and 2 in a skeleton.
2A, 2B, and 2C are a plan view and an elevation view showing a vibration state of the structure shown in FIG.
FIG. 3 is a perspective view showing a second embodiment of the vibration control frame according to the present invention by a skeleton.
4 is a plan view showing a vibration state of the structure of FIG. 3; FIG.
FIG. 5 is a perspective view showing a third embodiment of the vibration control frame according to the present invention by using a skeleton.
FIG. 6 is a perspective view showing a fourth embodiment of the vibration control frame according to the present invention by using a skeleton.
7 is a plan view showing a vibration state of the structure of FIG. 6. FIG.
FIG. 8 is a building model diagram of 1 mass point and 2 surfaces.
FIG. 9 is a diagram illustrating a maximum value of a transfer function.
10A is a comparative diagram of transfer functions according to a conventional design method, and FIG. 10B is a comparison diagram of transfer functions according to the design method of the present invention.
FIGS. 11A and 11B are explanatory diagrams of a rigid center position. FIGS.
[Explanation of symbols]
A Rigid construction surface B Flexible construction surface 3, 7 Damping device (damper)

Claims (2)

It is a seismic control frame that attaches a damping device to reduce the vibration response of the structure,
The frame of the structure is designed so that the stiffness and the center of gravity are decentered by breaking the balance of the rigidity of the structure or the mass of the structure so as to generate a torsional vibration in response to horizontal excitation.
The construction surface closer to the center of gravity than the center of gravity is defined as a rigid construction surface, and is disposed facing the rigid construction surface, and the construction surface on the side farther from the stiffness than the rigid construction surface is defined as a flexible surface. The damping frame is characterized in that damping devices are more concentratedly installed on the flexible surface than on the rigid surface . When the mass of the structure is uniform and there is a rigid element only on the outer peripheral surface of the structure , the rigidity ratio between the rigid surface and the flexible surface facing each other is designed to be 2: 1. The seismic control frame according to claim 1, wherein:

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