JP2016135944A - Base-isolation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base-isolation structure capable of stably and effectively reducing torsional vibration generated on the base-isolation structure on the occurrence of an earthquake without a large restriction on an installation position of a damper.SOLUTION: A base-isolation structure has a plurality of dampers installed on a base-isolation layer 3 between a superstructure and a substructure 1. The plurality of dampers are variable attenuation dampers 4 to 6 with attenuation coefficients thereof switched to higher values when relative displacement between the superstructure and the substructure exceeds thresholds. In the base-isolation structure, the variable attenuation dampers 4, which have smaller thresholds than the variable attenuation damper 6 arranged on an inner side of the base-isolation layer 3, are arranged on a peripheral side of a structure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a seismic isolation structure in which a damper is disposed in a seismic isolation layer, and more particularly to a seismic isolation structure that can obtain a damping effect and a torsional vibration suppressing effect when an earthquake occurs.

  Conventionally, as shown in, for example, Patent Document 1 below, a seismic isolation layer is formed by interposing a laminated rubber bearing or a sliding bearing between columns of the upper and lower structures of a building, and the upper structure of the building is shaken during an earthquake. In addition, a seismic isolation structure is known in which a damper such as an oil damper is interposed between the upper and lower structures to absorb relative displacement between the upper and lower structures and attenuate the shaking.

  By the way, in such a seismic isolation structure, since the rigidity in the seismic isolation layer is small, even a slight eccentricity tends to cause torsional vibration during an earthquake.

  Therefore, in the following Patent Document 2, the oil dampers are evenly arranged in the X direction and the Y direction along the outer periphery of the foundation plane, respectively, to increase the torsional resistance in the horizontal direction of the foundation plane, and during seismic isolation operation. Seismic isolation buildings have been proposed that prevent twisting of the foundations of structures.

JP 2006-292155 A JP 2007-332643 A JP 2002-310227 A JP 2007-231601 A JP 2010-255562 A

  However, in the conventional seismic isolation building described above, the rigidity of the seismic isolation layer is small, so that the installation position of the oil damper is greatly restricted in order to balance the seismic isolation layer, and the installable space is also limited. In addition, the effect of suppressing torsional vibration is limited.

  The present invention has been made in view of the above circumstances, and can stably and effectively reduce torsional vibration generated in a base-isolated structure during an earthquake without being greatly restricted by the installation position of the damper. The issue is to provide a seismic isolation structure.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a seismic isolation structure in which a plurality of dampers are installed in a seismic isolation layer formed between upper and lower structures, and at least a part of the plurality of dampers. As a variable damping damper whose damping coefficient changes according to the amount of relative displacement between the upper and lower parts structure, the damping coefficient of the damper located on the outer peripheral side of the structure at the time of an earthquake, It arrange | positions so that it may become higher than the damping coefficient of the said damper located inside.

  The invention according to claim 2 is the invention according to claim 1, wherein, as the plurality of dampers, variable damping dampers that switch to a high damping coefficient when the relative displacement exceeds a threshold value are used. The variable damping damper having a smaller threshold than the variable damping damper disposed on the inner side is disposed on the outer peripheral side of the structure.

  Further, the invention according to claim 3 is the invention according to claim 1, wherein the damper that does not change the damping coefficient is disposed on the inner side of the structure, and on the outer peripheral side of the structure. The variable damping damper is arranged so that when the relative displacement exceeds a threshold value, the damping coefficient is switched to a value having a higher damping coefficient than the inner damper.

  According to the invention according to any one of claims 1 to 3, as at least a part of the plurality of dampers installed in the seismic isolation layer, a variable whose damping coefficient changes according to the relative displacement amount between the upper and lower structures. Since a damping damper is used, acceleration can be reduced with a low damping force during small and medium-sized earthquakes with a small relative displacement, and the displacement can be reduced with a high damping force during a large earthquake with a large relative displacement. Can be reduced.

  In addition, since the damper is located so that the damping coefficient of the damper located on the outer circumference side of the structure is higher than the damping coefficient of the damper located on the inner side during an earthquake, the damping force on the outer circumference side of the structure is Therefore, the torsional vibration can be suppressed. As a result, the torsional vibration generated in the seismic isolation structure during an earthquake can be stably and effectively reduced without being greatly restricted by the installation position of the damper.

  According to the second aspect of the present invention, since the variable damping damper having a smaller threshold value than the variable damping damper disposed on the inner side is disposed on the outer peripheral side of the structure, the structure between the upper and lower structures during an earthquake is arranged. When the relative displacement increases, the outer variable damping damper is first switched to a higher damping coefficient than the inner variable damping damper, so that the above effect can be obtained.

  On the other hand, according to the third aspect of the present invention, a normal damper whose damping coefficient does not change is disposed inside the structure, and when the threshold is exceeded on the outer peripheral side, the damper is attenuated more than the inner damper. Since the variable damping damper whose coefficient is switched to a high value is disposed, the above-described effect can be achieved by switching the outer variable damping damper to a higher damping coefficient than the inner damper in the same manner during an earthquake.

It is a top view which shows arrangement | positioning of the variable damping damper in the 1st Embodiment of this invention. It is a top view which shows the operating state of a variable damping damper when the displacement of the seismic isolation layer of FIG. 1 is less than 10 cm. It is a top view which shows the operating state of a variable damping damper when the displacement of the seismic isolation layer of FIG. 1 is 10 cm-15 cm. It is a top view which shows the operating state of a variable damping damper when the displacement of the seismic isolation layer of FIG. 1 is 15 cm-20 cm. It is a top view which shows the operating state of a variable damping damper when the displacement of the seismic isolation layer of FIG. 1 is 20 cm or more. It is a top view which shows arrangement | positioning of the variable damping damper in the 2nd Embodiment of this invention.

(First embodiment)
1 to 5 show a first embodiment of a seismic isolation structure according to the present invention.
In these figures, in this seismic isolation structure, the seismic isolation layer 3 is formed by interposing a base isolation device 2 such as a laminated rubber bearing between the upper and lower structures (only the lower structure 1 is shown in the figure). Is formed. And in this seismic isolation layer 3, three types of oil dampers 4, 5 and 6 are arranged.

  These oil dampers 4, 5, and 6 are variable damping dampers that switch to a high damping coefficient when the relative displacement between the upper and lower structures 1 exceeds a threshold value. Before the threshold value is exceeded, the same damping is applied. Set to a coefficient. Here, the threshold value of the oil damper 4 is set to 10 cm. Further, the threshold value of the oil damper 5 is set to 15 cm, and the threshold value of the oil damper 6 is set to 20 cm. In addition, this kind of variable damping damper is a well-known thing as disclosed by the said patent documents 3-6, for example.

  And the oil damper 4 with the smallest threshold value is arrange | positioned in the outer peripheral part between the upper-and-lower part structure 1, and the oil damper 5 is arrange | positioned inside it. Further, the oil damper 6 having the largest threshold value is disposed on the innermost side.

  In the seismic isolation structure having the above configuration, as shown in FIG. 2, when the relative displacement between the upper and lower structures 1 is less than 10 cm, the oil dampers 4 to 6 are all set to a low damping coefficient when an earthquake occurs. In any case, the relative displacement between the upper and lower structures 1 is equally absorbed to attenuate the shaking.

  Next, as shown in FIG. 3, when the relative displacement is in the range of 10 cm to 15 cm, the oil damper 4 arranged on the outermost peripheral side is switched to a high damping coefficient. On the other hand, the other oil dampers 5 and 6 are both kept at a low damping coefficient.

  As shown in FIG. 4, when the relative displacement is in the range of 15 cm to 20 cm, the inner oil damper 6 is switched to a high damping coefficient in addition to the oil damper 4, thereby the innermost oil damper 6. Only is kept at a low attenuation coefficient.

  Further, when the relative displacement between the upper and lower structures 1 increases to 20 cm or more, as shown in FIG. 5, the innermost oil damper 6 is also switched to a high damping coefficient, so that all the oil dampers 4 to 4 are switched. 6 switches to a high attenuation coefficient.

  Thus, according to the seismic isolation structure, as the relative displacement between the upper and lower structures 1 increases during the earthquake, the damping coefficient sequentially increases from the outermost variable damping damper 4 to the inner variable damping dampers 5 and 6. By switching to a high value, the load of damping force on the outer peripheral side of the structure can be increased, and torsional vibration between the upper and lower structure 1 can be effectively suppressed, and the variable damping dampers 4, 5, 6 can be used. The relative displacement between the upper and lower structures 1 can be absorbed to attenuate the shaking.

  As a result, the torsional vibration generated in the base-isolated structure during an earthquake can be stably and effectively reduced without being greatly restricted by the installation position.

  Further, these oil dampers 4 to 6 are all set to a low damping coefficient when the relative displacement amount is less than 10 cm. Since the relative displacement amount is increased, the oil dampers 4 to 6 are sequentially switched to a higher damping coefficient. In a small and medium-sized earthquake with a small amount of displacement, acceleration can be reduced with a low damping force, and in a large earthquake with a large relative displacement amount, the displacement can be reduced with a high damping force.

(Second Embodiment)
FIG. 6 shows a second embodiment of the seismic isolation structure according to the present invention, and the same components as those shown in FIGS. .
In this seismic isolation structure, a normal oil damper (damper) 10 whose damping coefficient does not change is disposed inside the seismic isolation layer 3.

  An oil damper (variable damping damper) that switches to a higher damping coefficient than the oil damper 10 when the relative displacement between the upper and lower structures 1 exceeds a threshold value on the outer peripheral side of the structure in the seismic isolation layer 3. ) 11 is arranged.

  In the seismic isolation structure having the above configuration, a normal oil damper 10 whose damping coefficient does not change is arranged inside the structure, and the damping coefficient is higher than that of the inner oil damper 10 when the threshold value is exceeded on the outer peripheral side. Since the oil damper 11 that switches to the value is arranged, the outer oil damper 11 switches to a higher damping coefficient than the inner oil damper 10 in the event of an earthquake, so that the same effect as that shown in the first embodiment is achieved. Can be played.

  In the above embodiment, oil dampers 4, 5, 6, 10, and 11 are all used as variable damping dampers whose damping coefficient changes before and after the threshold and normal dampers whose damping coefficient does not change. However, the present invention is not limited to this, and it is possible to use various forms of variable damping dampers and dampers having a constant damping coefficient.

1 Substructure 2 Seismic isolation device 3 Seismic isolation layer 4, 5, 6, 11 Oil damper (variable damping damper)
10 Oil damper (damper)

Claims (3)

In the seismic isolation structure where multiple dampers are installed in the seismic isolation layer formed between the upper and lower structures,
As a damper of at least a part of the plurality of dampers, using a variable damping damper whose damping coefficient changes according to the relative displacement amount between the upper and lower structures,
The seismic isolation structure, wherein the plurality of dampers are arranged such that, in an earthquake, the damping coefficient of the damper located on the outer peripheral side of the structure is higher than the damping coefficient of the damper located inside. .   As the plurality of dampers, a variable damping damper that switches to a high damping coefficient when the relative displacement amount exceeds a threshold value, and the variable damping damper having a smaller threshold value than the variable damping damper disposed on the inside is used. The base-isolated structure according to claim 1, wherein the base-isolated structure is disposed on an outer peripheral side of the structure.   The damper, the damping coefficient of which does not change, is disposed on the inner side of the structure, and the damping coefficient is greater than that of the inner damper when the relative displacement exceeds a threshold value on the outer peripheral side of the structure. The seismic isolation structure according to claim 1, wherein the variable damping damper that switches to a high value is disposed.