JP2004360742A - Seismic isolating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seismic isolating device which reduces a locking moment by lengthening a period of a horizontal deviation of a structure by reducing a horizontal force of an opposite direction to the displacing direction of the structure operating at the structure in the case of an earthquake, even when an elastic seismic isolation member like a laminated rubber bearing is applied to the structure and which inhibits to generate a drawing force. <P>SOLUTION: The seismic isolating device includes the structure 1 supported by the laminated rubber bearing 2, and a coiled spring 4 installed as a repulsion generating means between the structure 1 and a substrate side 3. The horizontal force can be imparted in an opposite direction to the displacing direction of the structure 1 by the laminated rubber bearing 2. The horizontal force can be imparted in the same direction as the displacing direction of the structure 1 by the coiled spring 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seismic isolation device.
[0002]
[Prior art]
As a conventional seismic isolation device, for example, there is one as shown in FIG. In the figure, reference numeral 1 denotes a structure to be subjected to seismic isolation, and 2 denotes a laminated rubber bearing that is supported on the ground side 3 and is an elastic seismic isolator that supports the structure 1. In the laminated rubber bearing 2, rubber plates and steel plates are alternately laminated, and each contact surface is fixed. Thus, in such a seismic isolation device, the horizontal force generated by the horizontal displacement of the structure 1 during an earthquake is absorbed by the laminated rubber bearing 2.
[0003]
However, in the case of a vertically long structure 1 having a high aspect ratio (aspect ratio), a rocking phenomenon may occur as shown by an arrow A in FIG.
[0004]
As seismic isolation devices that reduce such rocking phenomena, seismic isolation devices that achieve a longer horizontal displacement by using both laminated rubber bearings and elastic sliding bearings, and linear guides that are used together with laminated rubber bearings There is a seismic isolation device (Patent Document 1) in which a locking moment is applied to a linear guide (horizontal movable support device).
[0005]
As a seismic isolation device provided with a coil spring between the ground side and a structure as in an example of the present invention, there is a device shown in Patent Document 2. However, in the present invention, the coil spring functions as repulsive force generating means, and the repulsive force is generated by the repulsive force generating means to increase the period of the horizontal displacement of the structure. In this method, a restoring force is applied by a coil spring so as to return a sliding partner of the sliding bearing to an initial position. Therefore, the present invention is fundamentally different from Patent Document 2 in technical idea.
[0006]
[Patent Document 1]
JP 2001-288928 A [Patent Document 2]
JP-A-11-280295
[Problems to be solved by the invention]
In the seismic isolation device of FIG. 10, the rocking phenomenon may occur as described above. However, when the locking phenomenon occurs, in the case of the vertically long structure 1 having a high aspect ratio, the pulling force is applied to the laminated rubber bearing 2. May occur, and the condition is poor.
[0008]
Further, in the case of a seismic isolation device in which the horizontal displacement is extended by using the above-mentioned laminated rubber bearing and elastic sliding bearing together, the locking phenomenon can be reduced, but the frictional force of the elastic sliding bearing is reduced. Since it depends on the surface pressure acting on the elastic slide bearing, it is difficult to manage the sliding surface of the elastic slide bearing in a predetermined state.
[0009]
Further, in the case of a seismic isolation device in which a linear guide is used in combination with a laminated rubber bearing so that a locking moment is applied to the linear guide as in Patent Document 2, the locking phenomenon can be reduced. In order to bear the pull-out force, the ground and the structure on which the linear guide is fixed must also be able to withstand the pull-out force.
[0010]
In view of the above circumstances, the present invention provides a horizontal force acting on a structure during an earthquake, which is opposite to the direction of displacement of the structure, even when an elastic seismic isolator such as a laminated rubber bearing is applied to the structure. The object of the present invention is to provide a seismic isolation device that reduces the rocking moment by increasing the period of the horizontal displacement of the structure by reducing the length of the horizontal displacement of the structure, and prevents the pull-out force from being generated. .
[0011]
[Means for Solving the Problems]
The seismic isolation device according to claim 1, wherein the structure is supported by an elastic seismic isolator supported on the ground side, and repulsive force generating means is installed between the structure and the ground side. Thus, a horizontal force can be applied in a direction opposite to the displacement direction of the structure, and a horizontal force can be applied in the same direction as the displacement direction of the structure by the repulsion generating means. .
[0012]
The seismic isolation device according to claim 2 is configured such that, when the structure is displaced by a predetermined amount in the horizontal direction, the absolute value of the horizontal force by the elastic seismic isolator is larger than the absolute value of the horizontal force by the repulsion generating means. It is.
[0013]
In the seismic isolation device of the third aspect, the elastic seismic isolator is a laminated rubber bearing.
[0014]
In the seismic isolation device of claim 4, the repulsion generating means is a coil spring, in the seismic isolation device of claim 5, the repulsion generating means is a leaf spring, and in the seismic isolation device of claim 6, The means is a magnet, and the repulsion generating means is a fluid pressure cylinder.
[0015]
ADVANTAGE OF THE INVENTION According to this invention, the period of the horizontal displacement of a structure is lengthened, a rocking moment is reduced, and since a pulling-out force does not generate | occur | produce, a trouble by a pulling-out force does not generate | occur | produce and furthermore, an elastic sliding support. Since there is no need to provide a sliding surface, there is no need to manage the sliding surface.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 7 show an example of the seismic isolation device of the present invention. The feature of the illustrated example is that, besides the laminated rubber bearing 2 which is an elastic seismic isolator for supporting the structure 1, the upper end is pivotally connected to the structure 1 and the lower end is the ground side 3. A coil spring 4 pivotally mounted on a pin 1 is provided between the structure 1 and the ground side 3 as repulsive force generating means. The coil spring 4 is held vertically as shown in FIG. 1 in an initial state in which no earthquake occurs, and when an earthquake occurs, the structure 1 can be displaced in the horizontal direction. FIG. 2 shows a state where the structure 1 is displaced rightward from the initial state of FIG.
[0017]
The coil spring 4 has a length L1 (see FIG. 3) in an initial state where no earthquake occurs and a length L2 (see FIG. 4) when the structure 1 is displaced in the horizontal direction at the maximum during the earthquake. It is set between the structure 1 and the ground side 3 in a state shorter than the natural length L when no load is applied to the coil spring 4. For this reason, the coil spring 4 is always kept in a state of being excessively compressed, and a repulsive force N is generated in the axial direction.
[0018]
The spring characteristic of the laminated rubber bearing 2 is shown in FIG. 5, and the relationship between the horizontal displacement x and the horizontal force F during an earthquake is a straight line. The horizontal force F is a force that acts in the direction opposite to the direction of displacement of the structure 1 when the structure 1 is displaced in the horizontal direction, and is a restoring force that attempts to return the structure 1 to its original position. In FIG. 5, the straight line is shown ascending to the right, and the horizontal force F when the structure 1 is displaced to the right as shown in FIG. 2 from the state of FIG. 1 is positive. The horizontal force F when displaced to the left from the state is set negative. Here, as is clear from FIG. 5, as the horizontal displacement x of the structure 1 increases, the horizontal force F for returning the structure 1 to the original position increases.
[0019]
The coil spring 4 generates a repulsive force N by a negative spring, and the spring characteristic when the structure 1 is displaced in the horizontal direction is a negative spring element characteristic. The negative spring characteristic of the coil spring 4 is shown in FIG. 6, and the relationship between the horizontal displacement x and the horizontal force W of the coil spring 4 during an earthquake is a curve. The horizontal force W is a force acting in the same direction as the direction of displacement of the structure 1 when the structure 1 is displaced in the horizontal direction, and is a force for further moving the structure 1 away from the original position. It is. In FIG. 6, the curve is shown at the lower right, and the horizontal force W when the structure 1 is displaced rightward from the state of FIG. 1 as shown in FIG. The horizontal force W when it is displaced to the left from the state is set positive. Here, as is clear from FIG. 6, when the horizontal displacement x of the structure 1 increases, the horizontal force W for displacing the structure 1 further in the direction away from the initial state increases. The horizontal force W is rightward in FIG.
[0020]
The overall spring stiffness of the seismic isolation device in the horizontal direction is the sum of the positive spring stiffness of the laminated rubber bearing 2 and the negative spring stiffness of the coil spring 4. The spring stiffness can be reduced.
[0021]
That is, the horizontal force S obtained by adding the horizontal force F by the laminated rubber bearing 2 and the horizontal force W by the coil spring 4 at the horizontal displacement x of the structure 1 is S = FW, and the spring of the laminated rubber bearing 2 is If the stiffness k1 is set to be larger than the spring stiffness k2 of the coil spring 4 (k1> k2), the absolute value | F | of the horizontal force F of the laminated rubber bearing 2 is equal to the coil spring 4 at a position where the displacement of the structure 1 is not zero. Is larger than the absolute value | W | of the horizontal force W (| F |> | W |), and as shown in FIG. 7, a gentle upward curve is obtained as shown in FIG. The spring stiffness k, which is the sum of the spring stiffness k1 of the laminated rubber bearing 2 and the spring stiffness k2 of the coil spring 4, is reduced, and the spring characteristics of the entire seismic isolation device are reduced.
[0022]
The horizontal force S acts in the direction opposite to the direction of displacement of the structure 1 when the structure 1 is displaced, and serves as a restoring force for returning the structure 1 to its original position. Even if the displacement x is large, the horizontal force S for returning the structure 1 to the original position is smaller than the horizontal force F for returning the structure 1 to the original position only by the laminated rubber bearing 2. .
[0023]
That is, in the illustrated example, when the structure 1 is displaced by receiving a horizontal force due to an earthquake, the structure 1 has a spring rigidity determined by the sum of the positive spring rigidity of the laminated rubber bearing 2 and the negative spring rigidity of the coil spring 4. , The reduced horizontal force S acts, and the structure 1 is gradually displaced in the horizontal direction. For this reason, the period of the horizontal displacement of the structure 1 becomes longer, and the rocking moment also decreases.
[0024]
Further, according to the illustrated example, since no pull-out force is generated, no problem occurs due to the pull-out force. Further, since there is no need to provide an elastic sliding bearing, there is no need to manage the sliding surface.
[0025]
8 and 9 show examples in which a leaf spring is used as a repulsive force generating means applied to the seismic isolation device of the present invention. In FIG. 8, as a repulsive force generating means, a plurality of leaf springs 5 are laminated and fixed on the lower surface of the structure 1, and a plurality of leaf springs 6 are laminated and fixed on the upper surface of the ground side 3, so that an initial earthquake-free state is obtained. The upper and lower ends of a rod 7, which is sometimes held vertically, are pivotally connected to leaf springs 5, 6. In FIG. 9, a leaf spring is not provided on the structure 1 side, but a leaf spring 6 is provided on the ground side 3, and the structure 1 and the leaf spring 6 are connected by a rod 7 similar to FIG. is there.
[0026]
In FIGS. 8 and 9, the center of the leaf spring 5 in the longitudinal direction is bent more downward than in the case where no load is applied in both cases of no earthquake and earthquake in order to generate a constant force. It is necessary that the center of the spring 6 in the longitudinal direction bend more upward than when no load is applied. That is, the radius of curvature of the leaf springs 5 and 6 needs to be larger than the radius of curvature in the free state.
[0027]
Even when the leaf springs 5 and 6 are used as the repulsive force generating means, the same operation and effect as when the coil spring 4 is used as in the above-described embodiment can be obtained. As a modification of FIGS. 8 and 9, a leaf spring 5 is provided only on the lower surface of the structure 1 as shown in FIG. 8, and no leaf spring is provided on the ground side 3. 3 may be connected by a rod 7.
[0028]
As the repulsive force generating means, in addition to the coil spring 4 and the leaf springs 5 and 6, for example, magnets may be provided on the structure 1 and the ground side 3 so that the same poles face each other, or an air spring may be used. May be installed vertically between the structure 1 and the ground side 3 in a state where the cylinder utilizing the pressure is urged in the direction in which the piston rod projects.
[0029]
Note that the seismic isolation device of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.
[0030]
【The invention's effect】
As described above, according to the seismic isolation device according to claims 1 to 7 of the present invention, the period of the horizontal displacement of the structure is lengthened, the locking moment is reduced, and no pulling force is generated. Therefore, various excellent effects can be obtained, such as no problem due to the pull-out force, and no need to provide an elastic sliding bearing, and no need to manage the sliding surface.
[Brief description of the drawings]
FIG. 1 is an elevation view showing an example of an embodiment of a seismic isolation device of the present invention, and is an elevation view showing a state in which no earthquake has occurred and no horizontal displacement has occurred.
FIG. 2 is an elevational view showing an example of an embodiment of the seismic isolation device of the present invention, and is an elevational view showing a state where a horizontal displacement occurs due to an earthquake.
FIG. 3 is an enlarged view of a portion of a coil spring in FIG. 1;
FIG. 4 is an enlarged view of a portion of a coil spring in FIG. 2;
FIG. 5 is a graph showing a relationship between a horizontal displacement when the structure shown in FIGS. 1 and 2 is displaced in a horizontal direction and a horizontal force generated by a laminated rubber bearing.
FIG. 6 is a graph showing a relationship between horizontal displacement and horizontal force generated by a coil spring when the structure shown in FIGS. 1 and 2 is displaced in a horizontal direction.
FIG. 7 is a graph showing the relationship between the horizontal displacement and the horizontal force of the structure obtained by combining the graphs shown in FIGS. 5 and 6;
FIG. 8 is an elevation view of another example of the repulsion generating means applied to the seismic isolation device of the present invention.
FIG. 9 is an elevation view of still another example of the repulsion generating means applied to the seismic isolation device of the present invention.
FIG. 10 is an elevation view of a conventional seismic isolation device.
[Explanation of symbols]
1 structure 2 laminated rubber bearing (elastic seismic isolation body)
3 Ground side 4 Coil spring (repulsive force generating means)
5 Leaf spring (repulsion generating means)
6 leaf spring (repulsive force generating means)
F Horizontal force W Horizontal force

Claims (7)

A structure is supported by an elastic seismic isolator supported on the ground side, and a repulsive force generating means is installed between the structure and the ground side. A seismic isolation device configured to apply a horizontal force in the opposite direction, and to apply a horizontal force in the same direction as the displacement direction of the structure by the repulsion generating means. 2. The seismic isolation device according to claim 1, wherein, when the structure is displaced in the horizontal direction by a predetermined amount, the absolute value of the horizontal force by the elastic seismic isolator is larger than the absolute value of the horizontal force by the repulsion generating means. 3. The seismic isolation device according to claim 1, wherein the elastic seismic isolator is a laminated rubber bearing. 4. The seismic isolation device according to claim 1, wherein the repulsion generating means is a coil spring. 4. The seismic isolation device according to claim 1, wherein the repulsion generating means is a leaf spring. 4. The seismic isolation device according to claim 1, wherein the repulsion generating means is a magnet. 4. The seismic isolation device according to claim 1, wherein the repulsion generating means is a fluid pressure cylinder.

Images