JP7698950B2 - Displacement suppression device and seismic isolation structure equipped with the same - Google Patents

Description

The present invention relates to a displacement suppression device (hereinafter referred to as a hardening type device) for a displacement-control type seismic isolation structure, and to a seismic isolation structure equipped with the same.

Traditionally, seismic isolation buildings have been known as a structural type that reduces earthquake input by extending the building period using seismic isolation devices such as laminated rubber. Because it can significantly reduce the response acceleration, it is also effective in preventing furniture from falling over during an earthquake.

However, in recent years, large earthquake waveforms have been observed more frequently, raising concerns that the displacement of seismically isolated buildings may exceed the design estimate and collide with retaining walls. Furthermore, measures against long-period, long-lasting earthquake motion have recently become necessary, and it is becoming important not only to extend the period but also to further suppress displacement.

When it comes to suppressing displacement, it is effective to increase damping by installing a large number of dampers, or to provide stoppers to avoid collisions with retaining walls. However, these measures lead to a shorter period of the building, which contradicts the reduction in response acceleration achieved by the longer period of a seismic isolation structure. For this reason, there is a demand for a structure that suppresses response displacement without compromising the effect of reducing response acceleration.

Conventional seismic isolation structures that suppress response displacement without compromising the effect of reducing response acceleration include, for example, structural types that combine a hardening device, a rotary inertia device, and a variable damper device (see, for example, Patent Documents 1 to 5).

On the other hand, vibration control devices that use tension members such as rope materials are known (see, for example, Patent Document 6). In a simple spring system in which rope materials are arranged in a direction perpendicular to the excitation direction, a third-order term appears when an equation of motion is derived taking into account geometric nonlinearity and approximated by Taylor expansion (see, for example, Non-Patent Document 1), and a hardening type restoring force characteristic can be realized. In addition, if the rope material is initially given slack, no force is generated until the slack is removed, resulting in a restoring force characteristic with a gap.

Arranging the rope material in a direction perpendicular to the excitation direction to realize hardening characteristics through geometric nonlinearity is a common method used in many experiments both overseas and domestically in research related to nonlinearity (see, for example, non-patent document 2).

JP 2019-178532 A JP 2017-003089 A JP 2017-003090 A Patent Application No. 2020-109632 (currently unpublished) Patent Application No. 2020-109654 (currently unpublished) JP 2003-138781 A

"Chaos in Dynamical Systems", by Ikuo Matsuba, Morikita Publishing Co., Ltd., pp.11-12, 2011 Steady State Passive Nonlinear Energy Pumping in Coupled Oscillators: Theoretical and Experimental Results, Xiaoai Jiang, D. Michael McFarland, Lawrence A. Bergman & Alexander F. Vakakis, Nonlinear Dynamics vol.33, pp.87-102, 2003

In a hardening-type device in which tension members such as ropes are arranged horizontally, they function only in one specific vibration direction. However, in an actual seismically isolated building, the upper building can move in any horizontal direction, so this arrangement causes problems. Therefore, some ingenuity is needed to make it possible to respond to any horizontal direction.

The clearance of the seismic isolation layer of a seismic isolated building is generally on the order of 50cm to 80cm, and the hardening device must have a mechanism that ensures that the rope material remains in its elastic range and does not break even when a large horizontal displacement occurs. One effective method for achieving this is to increase the length of the rope material (by separating the rope fixing positions as far as possible) to reduce the elongation of the rope material in response to horizontal displacement. However, stretching long rope material horizontally across the seismic isolation layer may interfere with layout planning and daily maintenance work.

In addition, it is necessary to generate large loads that will affect the vibration characteristics of the building, so components with sufficient rigidity are required.

In the case of high-rise seismically isolated buildings, the overturning moment of the building may cause additional axial forces in the seismic isolation devices, which may lead to damage to the devices. The additional axial forces are compressive forces in the seismic isolation devices on the side where the clearance between the building and the retaining wall is narrower, and pull-out forces in the seismic isolation devices on the side where the clearance is wider. Therefore, it is necessary to devise ways to mitigate the additional axial forces caused by the overturning moment.

The present invention has been made in consideration of the above, and aims to provide a hardening device that can effectively suppress the horizontal response displacement of a seismically isolated building using tension members, and a seismically isolated structure equipped with the same.

In order to solve the above problems and achieve the objectives, the hardening device of the present invention is a hardening device that is installed between an upper structure installed on a foundation via a seismic isolation member and a structure arranged opposite at least a part of the side wall of the upper structure with a gap, and is used to suppress the displacement of the upper structure, and is characterized in that it is equipped with a tension member that connects the side wall of the upper structure to the structure, and this tension member is arranged in a state inclined from the vertical direction.

Another hardening type device according to the present invention is characterized in that in the above-mentioned invention, the tension members are arranged with the structural body side on top and the superstructure side on the bottom in the vertical direction, and with the superstructure side closer to the corners of the underside of the superstructure and the structural body side farther from the corners of the underside of the superstructure in the horizontal direction.

Another hardening type device according to the present invention is characterized in that in the above-mentioned invention, the vertical height of the tension member is six times or more the gap between the side wall of the superstructure and the structure, and the horizontal length of the tension member is two times or more the gap between the side wall of the superstructure and the structure.

Another hardening type device according to the present invention is characterized in that, in the above-mentioned invention, it further comprises a resonance avoidance member for avoiding resonance of the tension member.

The seismic isolation structure according to the present invention is also characterized by being equipped with the above-mentioned hardening device.

The hardening device according to the present invention is a hardening device that is installed between an upper structure installed on a foundation via a seismic isolation member and a structure arranged opposite at least a part of the side wall of the upper structure with a gap, and is used to suppress the displacement of the upper structure. It is equipped with a tension member that connects the side wall of the upper structure to the structure, and this tension member is arranged in a state inclined from the vertical direction, so that the horizontal response displacement of the upper structure (seismically isolated building) can be effectively suppressed using the tension member.

In addition, with another hardening type device according to the present invention, the tension members are arranged vertically with the structure side facing up and the superstructure side facing down, and horizontally with the superstructure side closer to the corners of the underside of the superstructure and the structure side farther from the corners of the underside of the superstructure. Therefore, when the superstructure is displaced in any horizontal direction, tension is generated only in the tension member on the side where the gap is smaller. This has the effect of reducing the axial force acting on the compression side laminated rubber due to the overturning moment.

In addition, according to another hardening type device of the present invention, the vertical height of the tension member is six times or more the gap between the side wall of the superstructure and the structural body, and the horizontal length of the tension member is two times or more the gap between the side wall of the superstructure and the structural body. Therefore, when the superstructure is displaced in any horizontal direction, tension is generated only in the tension member on the side where the gap is smaller. This has the effect of reducing the axial force acting on the compression side laminated rubber due to the overturning moment.

In addition, another hardening type device according to the present invention further includes a resonance avoidance member for avoiding resonance of the tension member, which has the effect of avoiding resonance of the tension member.

In addition, the seismic isolation structure according to the present invention is equipped with the hardening device described above, and therefore has the effect of providing a seismic isolation structure that can suppress the horizontal response displacement of the superstructure.

FIG. 1 shows an embodiment of a hardening type device according to the present invention and a seismic isolation structure equipped with the same, where (1) is a side cross-sectional view and (2) is a plan cross-sectional view. FIG. 2 is an explanatory diagram of the rope material when colliding with a retaining wall, (1) showing a case where the superstructure moves only in the X direction, and (2) showing a case where the superstructure moves in both the X and Y directions. FIG. 3 is an explanatory diagram of other effects of this embodiment, in which (1) the effect of reducing the axial force acting on the compression-side laminated rubber due to the overturning moment, and (2) the effect of correcting the torsion of the seismic isolation layer. FIG. 4 shows a support material for avoiding resonance of a rope material, where (1) is a plan sectional view and (2) is a side sectional view. FIG. 5 is a side cross-sectional view showing another embodiment of the hardening type device and the seismic isolation structure equipped with the same according to the present invention.

Below, an embodiment of the hardening device according to the present invention and a seismic isolation structure equipped with the same will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment.

As shown in Figure 1, the hardening type device 10 according to the embodiment of the present invention is installed between an upper structure 16 provided via an underground seismic isolation layer 14 above a foundation 12 and a retaining wall 20 (structural body) arranged opposite the side wall 18 of the upper structure 16 with a seismic isolation layer clearance a (gap) therebetween, and is used to suppress the displacement of the upper structure 16. This hardening type device 10 is equipped with rope material 22 (22a, 22b: tension members) that connects the side wall 18 of the upper structure 16 and the retaining wall 20.

A laminated rubber layer 24 (seismic isolation member) is placed on the seismic isolation layer 14. The superstructure 16 is a building with a square horizontal cross section, and the retaining wall 20 is a wall body installed on the foundation 12, and is installed in a square shape so as to surround the superstructure 16 on all four sides. The seismic isolation structure 100 according to the embodiment of the present invention comprises the above-mentioned foundation 12, seismic isolation layer 14, superstructure 16, retaining wall 20, and hardening type device 10. Note that the superstructure is not limited to a square shape, and may have a cross section of a rectangular shape or the like.

The rope material 22 (22a, 22b) is arranged in the space of the seismic isolation layer clearance a in a state inclined from the vertical direction. More specifically, the rope material 22 is arranged so as to be connected in a manner in which the retaining wall 20 side is on top and the upper structure 16 side is on the bottom in the vertical direction. In addition, the rope material 22 is arranged so that the upper structure 16 side is closer to the four corners (lower surface corners) of the lower surface of the upper structure 16 in the horizontal plane, and the retaining wall 20 side is farther from the four corners of the lower surface of the upper structure 16. The vertical height b of the rope material 22 is preferably set to a length sufficiently larger than the seismic isolation layer clearance a, and is preferably set to, for example, six times or more of the seismic isolation layer clearance a. In addition, the horizontal length c of the rope material 22 is preferably set to a value smaller than the height b of the rope material 22 and to two times or more of the seismic isolation layer clearance a between the side wall 18 of the upper structure 16 and the retaining wall 20.

Next, the function and effect of the rope material 22 (22a, 22b) arranged as described above will be described.
As shown in FIG. 1 (2), if the X and Y directions are set in a horizontal plane, the seismic isolation layer clearance is a, the height of the rope material 22 is b, and the horizontal length of the rope material 22 is c, then the length of the rope material 22 when there is no slack will be L0 = (a×a + b×b + c×c) ^0.5 .

First, let us consider the case where the upper structure 16 moves in the X direction by x = a, i.e., the rope material 22 when it collides with the retaining wall. Figure 2 (1) shows the situation after the movement. However, because it is symmetrical about the X axis, only the lower half of the rope material is shown.

The following description will focus on rope materials 1 and 2 in Figure 2 (1). Note that rope material 3 is in the direction in which the material shrinks, so no force is generated.
The length of the rope material 1 is L1x = (a x a + b x b + (c + a) x (c + a)) ^0.5
The length of the rope material 2 is L2x = ((a + a) x (a + a) + b x b + c x c) ^0.5
Here, if c>2×a is set, then L1x>L2x.

If the rope material is given slack and the natural length of the rope is set to L = L2x = ((a + a) x (a + a) + b x b + c x c) ^0.5 , rope material 2 will also not bear the tension. Therefore, by using a rope material with slack, only rope material 1 can generate tension.

Next, we consider the case where the upper structure 16 moves by x=a in the X direction and by y=a in the Y direction. Figure 2 (2) shows the situation after the movement. However, because of 45-degree axial symmetry, only the lower right side of the rope material is shown.

The following description will focus on rope materials 1, 2, and 4 in Figure 2 (2). Note that rope material 3 is in the direction in which the material shrinks, so no force is generated.
The length of the rope material 1 is L1xy = ((a+a) x (a+a) + b x b + (c+a) x (c+a)) ^0.5
The length of the rope material 2 is L2xy = ((a + a) x (a + a) + b x b + (c - a) x (c - a)) ^0.5
The length of the rope material 4 is L3xy = ((a + a) x (a + a) + b x b + (c + a) x (c + a)) ^0.5

The natural length of the rope including slack is L = ((a + a) x (a + a) + b x b + c x c) ^0.5 .
Here, if c>2×a is set, then L>L2xy will be obtained, and no tension will be generated in the rope material 2.
Furthermore, L<L3xy, and tension is generated in the rope material 4.

As described above, when the upper structure 16 moves in any horizontal direction, tension is generated only in the rope material 22 on the side where the seismic isolation layer clearance a is smaller.

Therefore, according to this embodiment, by arranging the rope material 22 in a substantially vertical direction, any horizontal response displacement of the superstructure 16 can be effectively suppressed using the rope material 22. In addition, by utilizing the rope material 22, which can be manufactured inexpensively, a hardening type restoring force characteristic due to geometric nonlinearity can be realized.

In addition, as shown in FIG. 3 (1), the tension acts in the direction of lifting the upper structure 16, which also has the effect of reducing the axial force acting on the compression side of the laminated rubber 24 due to the overturning moment.

The arrangement of the rope material 22 is also effective against twisting of the seismic isolation layer 14. As shown in Figure 3 (2), when the upper structure 16 is displaced counterclockwise, a tensile force is generated in the rope material 22 indicated by the arrow, which functions in a direction to correct the twisting.

However, since the rope material 22 is long, it may resonate during an earthquake. Therefore, as shown in FIG. 4, a support material 26 (resonance avoidance member) may be further provided to avoid resonance of the rope material 22. The support material 26 is installed from near the center of the rope material 22 to the retaining wall 20. The material of the support material 26 may be an elastic material such as rubber. When only one support material 26 is used, there is a possibility of resonance in a direction perpendicular to the plane formed by the rope material 22 and the support material 26, so it is preferable to use two or more support materials 26 and arrange them so that all the materials (rope material 22, support material 26) are not on the same plane. Furthermore, the support material 26 may be provided with a damping function to actively avoid resonance and to reduce vibration by absorbing energy.

In the above embodiment, the rope material 22 is placed in the space of the seismic isolation layer clearance a of the underground seismic isolation layer 14, but the present invention is not limited to this, and the rope material 22 may be placed anywhere as long as sufficient space can be secured vertically. For example, as shown in FIG. 5 (1), in a void-type superstructure 16 with a structure 28 placed in the center, the rope material 22 can be placed in the space between the structure 28 and the superstructure 16. Also, as shown in FIG. 5 (2), a column 30 may be provided outside the superstructure 16, and the rope material 22 may be placed between the column 30 and the superstructure 16.

(Example)
Next, an embodiment of the present invention will be described. This embodiment is applied to the following specifications.
Seismic isolation layer clearance a = 0.75 m
Rope height b = 6m (=8 x a)
Horizontal length of rope material c = 3 m (= 4 x a)

Length of rope material without slack L0 = (a x a + b x b + c x c) ^0.5 = 6.750 m
If the superstructure moves in the X direction by x = a, Lx = (a x a + b x b + (c + a) x (c + a)) ^0.5 = 7.115 m
If the superstructure moves in the Y direction by y = a, Ly = ((a + a) x (a + a) + b x b + c x c) ^0.5 = 6.874 m
If the superstructure moves by x = a and y = a, Lxy = ((a + a) x (a + a) + b x b + (c + a) x (c + a)) ^0.5 = 7.233 m
If the length of the rope material with slack is L = Ly = 6.874 m, the strain when the superstructure moves by x = a, y = a is 7.233/6.874 = 1.052 (strain = 5.2%).

Here, a normal wire rope would break at a strain of about 5%, making it difficult to use as a rope material. As a rope material for this embodiment, for example, a synthetic fiber rope used for mooring lines in the marine and ship fields is useful. A variety of synthetic fiber ropes are available with elongation at break of about 4% to 30%, and are lighter than steel wire rope materials, allowing them to be used under harsh conditions. Because of their light weight, installation and maintenance work is easier.

Considering the safety factor, it is desirable to keep the strain to around 5% even when using synthetic fiber ropes. The strain can be reduced by increasing the rope material height b, but as mentioned above, it is desirable for the rope material height b to be at least six times the seismic isolation layer clearance a.

According to this embodiment, it is possible to effectively suppress any horizontal response displacement of the superstructure.

As described above, the hardening device of the present invention is a hardening device that is installed between an upper structure installed on a foundation via a seismic isolation member and a structure arranged opposite at least a part of the side wall of the upper structure with a gap, and is used to suppress the displacement of the upper structure, and is equipped with a tension member that connects the side wall of the upper structure to the structure, and this tension member is arranged in a state inclined from the vertical direction, so that the horizontal response displacement of the upper structure (seismically isolated building) can be effectively suppressed using the tension member.

In addition, with another hardening type device according to the present invention, the tension members are arranged vertically with the structure side facing up and the superstructure side facing down, and horizontally with the superstructure side closer to the corners of the underside of the superstructure and the structure side farther from the corners of the underside of the superstructure. Therefore, when the superstructure is displaced in any horizontal direction, tension is generated only in the tension member on the side where the gap is smaller. This makes it possible to reduce the axial force acting on the compression side laminated rubber due to the overturning moment.

In addition, according to another hardening type device of the present invention, the vertical height of the tension member is six times or more the gap between the side wall of the superstructure and the structural body, and the horizontal length of the tension member is two times or more the gap between the side wall of the superstructure and the structural body. Therefore, when the superstructure is displaced in any horizontal direction, tension is generated only in the tension member on the side where the gap is smaller. This makes it possible to reduce the axial force acting on the compression side laminated rubber due to the overturning moment.

In addition, another hardening type device according to the present invention further includes a resonance avoidance member for avoiding resonance of the tension member, so that resonance of the tension member can be avoided.

In addition, the seismic isolation structure according to the present invention is equipped with the hardening device described above, so that it is possible to provide a seismic isolation structure that can suppress the horizontal response displacement of the superstructure.

As described above, the hardening device of the present invention and the seismic isolation structure equipped with the same are useful for seismic isolation structures, and are particularly suitable for effectively suppressing the horizontal response displacement of seismically isolated buildings.

10 Hardening type device 12 Foundation 14 Seismic isolation layer 16 Superstructure 18 Side wall 20 Retaining wall (structural body)
22, 22a, 22b Rope material (tension member)
24 Laminated rubber (seismic isolation material)
26 Support material (resonance avoidance material)
28 Structure 30 Column 100 Seismic isolation structure a Seismic isolation layer clearance (gap)
b Height of rope material c Horizontal length of rope material

Claims (4)

A device that is provided between a superstructure provided on a foundation via a seismic isolation member and a structure that is disposed opposite at least a part of a side wall of the superstructure with a clearance therebetween, and is used to suppress displacement of the superstructure,
A displacement suppression device comprising a tension member connecting the side wall of the upper structure and the structural body , and a resonance avoidance member for avoiding resonance of the tension member , wherein the tension member is arranged in the clearance space at an angle from the vertical direction. The displacement suppression device according to claim 1, characterized in that the tension member is arranged vertically with the structure side facing up and the superstructure side facing down, and horizontally with the superstructure side facing closer to the corners of the underside of the superstructure and the structure side facing away from the corners of the underside of the superstructure. The displacement suppression device according to claim 1 or 2, characterized in that the vertical height of the tension member is six times or more the clearance between the side wall of the superstructure and the structure, and the horizontal length of the tension member is two times or more the clearance between the side wall of the superstructure and the structure. A seismic isolation structure comprising a displacement suppression device according to any one of claims 1 to 3 .

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