JP7679966B2 - Displacement limiting device - Google Patents

Description

This invention relates to a displacement limiting device, and more specifically, to a device for preventing damage to a building, for example, in which a seismic isolation device is installed, due to excessive displacement occurring therein.

Seismically isolated buildings are known in which seismic isolation devices are installed between the building and its foundation. Seismic isolation devices consist of laminated rubber bearings and other components, and support the load of the building while reducing the transmission of seismic forces to the building by undergoing shear deformation during an earthquake.

However, unexpected earthquake motion exceeding level 2 may cause excessive deformation in the seismic isolation device. In addition, repeated deformation caused by long-period earthquake motion may cause the performance of the seismic isolation device to deteriorate, raising concerns that the response displacement of the seismic isolated building may become excessive. If the response displacement becomes excessive, the seismic isolated building may collide with the retaining walls surrounding the building, causing the building to shake violently due to the impact force, and causing damage to the building.

One method known in the art for dealing with the above phenomenon is to install rubber between the building and the retaining wall to reduce the impact (see, for example, Patent Document 1). However, while this method of installing cushioning rubber can cushion the impact, it cannot eliminate the impact on the building, and therefore cannot completely avoid the effects of large shaking of the building, etc.

In addition, the clearance between the building and the retaining wall is difficult to control due to construction errors, making it difficult to accurately verify the response during a collision. Furthermore, although shock-absorbing rubber can absorb vibration energy, it cannot be expected to provide a significant damping effect.

JP 2016-199910 A

The present invention has been made based on the above technical background, and has the following objectives.
The object of the present invention is to provide a displacement limiting device that can be installed, for example, in conjunction with a seismically isolated building, thereby avoiding collision between the building and a retaining wall due to excessive deformation of the seismic isolation device, thereby preventing large shaking and damage to the building, and further significantly attenuating vibration energy.

In order to achieve the above object, the present invention employs the following means.
That is, the present invention provides a device for limiting relative displacement occurring between two structures having opposing surfaces in a direction parallel to the surfaces, comprising:
A cylindrical body disposed substantially parallel to the surface, one end of which is connected to the surface of one of the structures;
a rod disposed substantially parallel to the surface and having one end connected to the surface of the other structure;
A movable end plate having a plurality of protrusions on its outer periphery is provided at both ends of the cylindrical body so as to be movable in the axial direction perpendicular to the axis of the cylindrical body, and the movable end plate is guided and movable by fitting the protrusions into a plurality of notched grooves which are provided at intervals in the circumferential direction at both ends of the cylindrical body and extend in the axial direction of the cylindrical body,
the other end of the rod is inserted into the inside of the cylindrical body by passing through the movable end plate at the other end of the cylindrical body so as to be freely movable in the axial direction;
a head that is slidable along an inner periphery of the cylindrical body in an axial direction and moves the movable end plate is provided at the other end of the rod;
The displacement limiting device is characterized in that an energy absorbing member made of low yield point steel is provided between the protrusion of the movable end plate and the outer circumferential middle portion of the cylindrical body, extending in the axial direction of the cylindrical body.

In the above-mentioned displacement limiting device , a configuration can be adopted in which the head has a built-in buffer spring that elastically deforms when the head collides with the movable end plate due to movement of the rod.

the head includes a cylindrical portion disposed on the outer periphery of the other end of the rod and slidably disposed on the inner periphery of the cylindrical body in the axial direction, end plates provided on both ends of the cylindrical portion and having a hole through which the other end of the rod can move in the axial direction, and an annular protrusion provided on the outer periphery of the rod between the end plates,
The buffer spring may be provided between each of the end plates and the annular projection.

The buffer spring may also be configured as a disc spring arranged to surround the rod.

The two structures may be configured as the building and foundation of a seismically isolated building. Furthermore, the two structures may be configured as the upper structure and lower structure sandwiching the seismic isolation layer in a seismically isolated building in which the seismic isolation layer is located in the middle layer.

According to this invention, when installed in a seismically isolated building, for example, excessive deformation of the seismic isolation device is suppressed, so collisions between the building and the retaining wall can be avoided, large shaking and damage to the building can be prevented, and vibration energy can be significantly attenuated.

FIG. 2 is a front view showing an outline of a seismically isolated building. 1A and 1B show an embodiment of a displacement limiting device according to the present invention, in which FIG. 1A is a plan view and FIG. 3 is a cross-sectional view taken along the line A in FIG. 2( a ). 3 is a cross-sectional view taken along the line B in FIG. 2( a ). FIG. 3 is a cross-sectional view taken along the line C in FIG. FIG. FIG. 4 is a perspective view showing a holding member for the energy absorbing member. FIG. 2 is a perspective view showing an energy absorbing member. 5A and 5B are axial cross-sectional views showing the contraction operation state of the displacement limiting device, in which (a) shows a state in which the buffer spring is in operation, and (b) shows a state in which the energy absorbing member is in operation following the buffer spring. 5A and 5B are axial cross-sectional views showing the extension operation state of the displacement limiting device, in which (a) shows a state in which the buffer spring is in operation, and (b) shows a state in which the energy absorbing member is in operation following the buffer spring.

An embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a front view showing an outline of a seismically isolated building. A number of seismic isolation devices 13 are installed between a foundation 11, which is surrounded by a retaining wall 12, and a building 10, and the load of the building 10 is supported by these seismic isolation devices 13.

The seismic isolation device 13 is composed of a well-known laminated rubber bearing formed, for example, by alternately laminating rubber layers and steel plates. During an earthquake, the laminated rubber bearing undergoes horizontal shear deformation, reducing the transmission of vibrations to the building. A clearance of a required size is provided between the building 10 and the retaining wall 12 to allow for horizontal displacement of the building 10 during an earthquake.

If the seismic isolation device 13 is subjected to repeated deformation due to long-period seismic motion, its performance may deteriorate, causing the response displacement of the building 10 to become excessive. The displacement limiting device 14 is installed between the building 10 and the foundation 11 to prevent excessive displacement of the building 10 during an earthquake, i.e., excessive displacement of the seismic isolation device 13.

Figure 2 shows the displacement limiting device 14, where (a) is a plan view and (b) is an axial cross-sectional view. Figures 3, 4, and 5 are cross-sectional views taken along the lines A, B, and C of Figure 2(a), respectively.

The displacement restriction device 14 comprises a cylindrical body 15 arranged approximately parallel to the opposing surfaces of two structures, the building 10 and the foundation 11, and a rod 16. One end of the cylindrical body 15 is provided with a pair of clevises 17a, 17b connected by a pin 18. The connecting plate 19 of one clevis 17a is fixed to one end face of the cylindrical body 15. The connecting plate 20 of the other clevis 17b is fixed to the building 10.

Similarly, one end of the rod 16 is provided with a pair of clevises 21a, 21b connected by a pin 22. One of the clevises, 21a, is fixed to one end of the rod 16 by a screw. The connecting plate 23 of the other clevis, 21b, is fixed to the foundation 11.

Movable end plates 24a, 24b are disposed at both ends of the cylindrical body 15. As shown in Fig. 6, the movable end plates 24a, 24b have a plurality of (three in this embodiment) protrusions 26 formed at intervals in the circumferential direction on the outer periphery of a disk portion 25 having a diameter substantially equal to the inner diameter of the cylindrical body 15. Meanwhile, notched grooves 27 are formed at both ends of the cylindrical body 15, the number of which corresponds to the number of the protrusions 26, and extend in the axial direction of the cylindrical body 15 at intervals in the circumferential direction.

The multiple protrusions 26 of the movable end plates 24a, 24b are fitted into the notched grooves 27 of the cylindrical body 15. This positions the movable end plates 24a, 24b perpendicular to the axis of the cylindrical body 15, and the protrusions 26 are guided by the notched grooves 27, allowing them to move freely in the axial direction.

As shown in FIG. 6, a hole 50 (shown in phantom lines) is provided in the movable end plate 24b on the other end side of the cylindrical body 15. The other end of the rod 16 passes through the movable end plate 24b via this hole 50 so as to be freely movable in the axial direction, and is inserted into the inside of the cylindrical body 15. A head 28 is provided on the other end of the rod 16, which is freely slidable in the axial direction on the inner circumference of the cylindrical body 15. Details of the head 28 will be described later.

A plurality of energy absorbing members 29 (three per end plate in this embodiment) are provided between the movable end plates 24a, 24b and the outer periphery of the cylindrical body 15, extending in the axial direction at circumferential intervals. The plurality of energy absorbing members attached to the movable end plates 24a, 24b are alternately arranged in the circumferential direction of the cylindrical body 15 to facilitate setting the length.

The energy absorbing member 29 is made of low yield point steel with a predetermined length, width and thickness. As shown in FIG. 8, the energy absorbing member 29 has widened sections 30a, 30b at both ends, and the transitional portion from the widened sections 30a, 30b to the middle section is rounded 40. The end on the widened section 30a side is attached to the movable end plates 24a, 24b, and the end on the widened section 30b side is attached to the cylindrical body 15.

In order to attach one end of this energy absorbing member 29 to the movable end plates 24a, 24b, a groove 31 is provided at the tip of the protrusion 26 of the movable end plates 24a, 24b. Both walls of this groove 31 are provided with R processing 41 that corresponds to the R processing 40 of the energy absorbing member 29.

One end of the energy absorbing member 29 is held in the groove 31 with the widened portion 30a protruding from the groove 31. A pressing plate 32 is arranged to cover the groove 31, and the pressing plate 32 is fixed to the protrusion 26 by a bolt 33. Reference numeral 34 in FIG. 6 indicates a mounting hole for the bolt 33.

The other end of the energy absorbing member 29 is attached to the tubular member 15 via a retaining member 35 shown in FIG. 7. The retaining member 35 has a groove 36 similar to the projections 26 of the movable end plates 24a, 24b, and is fixed to the tubular body 15 by a bolt 37. This groove 36 also has a rounded edge 44 on both walls that corresponds to the rounded edge 40 of the energy absorbing member 29. Reference numeral 38 in FIG. 7 indicates the mounting hole for the bolt 37.

The other end of the energy absorbing member 29 is held in the groove 36 with the widened portion 30b protruding from the groove 36. A pressing plate 39 is disposed to cover the groove 36, and the pressing plate 39 is fixed to the holding member 35 by a bolt 42. The reference numeral 43 in FIG. 7 indicates the mounting hole for the bolt 42.

The head 28 provided at the other end of the rod 16 has a cylindrical portion 45 arranged on the outer periphery of the rod 16 and slidably in the axial direction on the inner periphery of the cylindrical body 15. A sliding material made of polytetrafluoroethylene resin or the like is provided on the outer periphery of the cylindrical portion 45 to ensure smooth sliding. Such a sliding material is also provided on the inner periphery of the hole 50 of the movable end plate 24b. End plates 46a, 46b are fixed to both ends of the cylindrical portion 45. The end plates 46a, 46b are provided with holes 47a, 47b that receive the other end of the rod 16 movably in the axial direction.

A ring-shaped protrusion 48 is provided on the outer periphery of the rod 16 between the end plates 46a, 46b. A number of disc springs 49a, 49b constituting a buffer spring are arranged on both sides of the ring-shaped protrusion 48, i.e., between the ring-shaped protrusion 48 and the end plates 46a, 46b, surrounding the rod 16. With the disc springs 49a, 49b in place, the rod 16 is positioned so that its tip surface is recessed a predetermined distance d inward in the axial direction of the cylindrical portion 45. This distance d is the displacement allowance of the rod 16 relative to the cylindrical portion 45 in order to compress the disc springs 49a.

Next, the operation of the displacement limiting device 14 will be explained. Figure 2 shows the building 10 in a neutral state where no displacement due to an earthquake or the like has occurred. In the neutral state, the head 28 is in the center between the movable end plates 24a and 24b, i.e., in a position where the distance s between the tip surface of the head 28 and the movable end plate 24a and the distance s between the rear end surface of the head 28 and the movable end plate 24b are approximately equal.

If the displacement of the building 10 due to an earthquake or the like, i.e., the displacement of the seismic isolation device 13, is within distance s, the displacement limiting device 14 will expand and contract, but no displacement will occur in the disc springs 49a, 49b or the energy absorbing member 29. Note that the expansion and contraction of the displacement limiting device 14 refers to the extension of the rod 16 being pulled out of the cylindrical body 15 and the shortening of the rod 16 being pulled into the cylindrical body 15.

When an earthquake or the like occurs that causes the displacement of the seismic isolation device 13 to exceed distance s, the displacement limiting device 14 operates as shown in Figures 9 and 10. Figure 9 shows the state of the displacement limiting device 14 when it is contracted. When it is contracted, the end plate 46a of the head 28 collides with the movable end plate 24a, and the rod 16 is first displaced within a range of distance d relative to the cylindrical portion 45. This causes the disc spring 49a to compress, mitigating the impact (state in Figure 9(a)).

When the deformation of the disc spring 49a reaches the compression limit (in the illustrated embodiment, when the displacement of the rod 16 relative to the cylindrical body 45 reaches the distance d), the head 28 presses the movable end plate 24a to move it along the notch groove 27. However, since the energy absorbing member 29 is connected to the movable end plate 24a, the energy absorbing member 29 opposes the movement of the movable end plate 24a and restricts the displacement of the rod 16, i.e., the displacement of the seismic isolation device 13.

On the other hand, since the energy absorbing member 29 is made of low-yield-point steel, it easily yields and elongates due to the tensile force from the movable end plate 24a, allowing the movable end plate 24a to move (state shown in FIG. 9(b)). This allows the vibration energy caused by earthquakes or the like applied to the building 10 to be attenuated.

Figure 10 shows the state of the displacement limiting device 14 when it is extended. During extension, the end plate 46b of the head 28 collides with the movable end plate 24b, and the rod 16 is first displaced relative to the cylindrical portion 45. This causes the disc spring 49b to compress, mitigating the impact (state in Figure 10(a)).

When the deformation of the disc spring 49b reaches its compression limit, the head 28 presses the movable end plate 24b, causing it to move along the notch groove 27. However, because the energy absorbing member 29 is connected to the movable end plate 24b in the same way as the movable end plate 24a, the energy absorbing member 29 opposes the movement of the movable end plate 24b and restricts the displacement of the rod 16, i.e., the displacement of the seismic isolation device 13.

The energy absorbing member 29 connected to the movable end plate 24b is also made of low yield point steel, just like the one connected to the movable end plate 24a, so it easily yields and elongates due to the tensile force from the movable end plate 24b, allowing the movable end plate 24b to move (state shown in Figure 10(b)). This allows the vibration energy caused by earthquakes, etc., applied to the building 10 to be attenuated. In other words, the displacement limiting device 14 can restrain the displacement of the seismic isolation device 13 during both its extension and contraction operations, and can also attenuate the vibration energy applied to the building 10.

According to the above embodiment, the following advantageous effects can be obtained.
(1) When the displacement of the seismic isolation device exceeds a specified value, the energy absorbing member activates to restrict the displacement, preventing excessive deformation of the seismic isolation device and preventing collisions between the building and the retaining wall, thereby preventing large shaking and damage to the building. (2) Since the energy absorbing member is made of low-yield-point steel, it can significantly attenuate the vibration energy applied to the building.

(3) A shock absorbing spring is built into the head at the end of the rod, which collides with the movable end plate to activate the energy absorbing member, so that the impact when the head collides with the movable end plate can be reduced.

The above embodiment is merely illustrative, and the invention can take various forms. For example, in the above embodiment, the cylindrical body of the displacement limiting device is connected to the building and the rod is connected to the foundation, but the cylindrical body may be connected to the foundation and the rod to the building. The displacement limiting device can also be installed between the upper structure and lower structure that sandwich the seismic isolation layer in a building where the seismic isolation layer is located in the middle layer. The displacement limiting device of this invention is not limited to application to seismic isolated buildings, and can be used for other purposes as long as it is used to limit the relative displacement that occurs between two structures that have opposing surfaces.

10: Building 11: Foundation 12: Retaining wall 13: Seismic isolation device (laminated rubber bearing)
14: Displacement limiting device 15: Cylindrical body 16: Rod 24a, 24b: Movable end plate 26: Protrusion 27: Notch groove 28: Head 29: Energy absorbing member

Claims (6)

A device for limiting relative displacement between two structures having opposing surfaces in a direction parallel to the surfaces, comprising:
A cylindrical body disposed substantially parallel to the surface, one end of which is connected to the surface of one of the structures;
a rod disposed substantially parallel to the surface and having one end connected to the surface of the other structure;
A movable end plate having a plurality of protrusions on its outer periphery is provided at both ends of the cylindrical body so as to be movable in the axial direction perpendicular to the axis of the cylindrical body, and the movable end plate is guided and movable by fitting the protrusions into a plurality of notched grooves which are provided at intervals in the circumferential direction at both ends of the cylindrical body and extend in the axial direction of the cylindrical body,
the other end of the rod is inserted into the inside of the cylindrical body by passing through the movable end plate at the other end of the cylindrical body so as to be freely movable in the axial direction;
a head that is slidable along an inner periphery of the cylindrical body in an axial direction and moves the movable end plate is provided at the other end of the rod;
A displacement limiting device characterized in that an energy absorbing member made of low yield point steel is provided between the protrusion of the movable end plate and the outer circumferential middle portion of the cylindrical body, extending in the axial direction of the cylindrical body. The displacement limiting device according to claim 1, characterized in that the head has a built-in buffer spring that elastically deforms when the head collides with the movable end plate due to the movement of the rod. the head includes a cylindrical portion disposed on the outer periphery of the other end of the rod and slidably disposed on the inner periphery of the cylindrical body in the axial direction, end plates provided on both ends of the cylindrical portion and having a hole through which the other end of the rod can move in the axial direction, and an annular protrusion provided on the outer periphery of the rod between the end plates,
3. The displacement limiting device according to claim 2, wherein said buffer springs are provided between each of said end plates and said annular projection. The displacement limiting device according to claim 3, characterized in that the buffer spring is a disc spring arranged around the rod. A displacement limiting device according to any one of claims 1 to 4, characterized in that the two structures are a building and a foundation in a seismically isolated building. The displacement limiting device according to any one of claims 1 to 4, characterized in that the two structures are an upper structure and a lower structure that sandwich a seismic isolation layer in a seismic isolation building in which the seismic isolation layer is located in the middle layer.

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