Seismic isolation stopper and seismic isolation building

Abstract

To provide a base isolation stopper and a base isolated building capable of preventing excessive deformation in a giant earthquake without narrowing a clearance of a base isolation layer.SOLUTION: A base isolation stopper 10 for suppressing displacement of a base isolation layer 3 provided between an upper structure 4 and a lower structure 2 comprises a displacement suppression part 11 embedded in a retaining wall 5 provided at a position facing the base isolation layer around the upper structure, and a linear member 12 bridged between the upper structure and the displacement suppression part, and when the upper structure is relatively moved by a predetermined amount with respect to the lower structure, the linear member is tensed and the displacement suppression part functions.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a seismic isolation stopper and a seismic isolated building. [Background technology]

[0002] A seismic isolation structure is a structure in which a seismic isolation layer is installed mainly in the foundation of a building, and during an earthquake, the seismic isolation layer undergoes large horizontal deformation, reducing the acceleration response of the superstructure, and the seismic isolation layer efficiently absorbs input energy.Because a seismic isolation structure can significantly reduce the response acceleration of the superstructure even during a major earthquake, it not only prevents structural damage to the building, but also achieves high seismic performance that makes it possible to maintain the building's functions after an earthquake.

[0003] In recent years, the level of seismic motion that must be considered when designing buildings has been increasing, raising concerns about long-period, extended seismic motion from mega-earthquakes in the Nankai Trough or Sagami Trough, as well as long-period pulse seismic motion from inland active fault earthquakes such as the Uemachi Fault. In particular, long-period pulse seismic motion, such as that observed in the 2016 Kumamoto earthquake, can cause excessive deformation of over 1 meter in seismic isolation layers, and increasing the damper alone is not enough to prevent this deformation. If such seismic motion causes the seismic isolation layer to displace beyond its clearance and the superstructure to collide with the retaining wall, excessive acceleration can occur in the superstructure, potentially resulting in damage. To prevent this, stoppers that prevent the seismic isolation layer from deforming excessively beyond its clearance and crash buffers that cushion the impact of a collision have been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-77229 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the shock-absorbing member used in Patent Document 1 is attached to the surface of the retaining wall, which reduces the clearance of the seismic isolation layer. Also, in the seismic isolation layer where many equipment pipes and other components are installed, securing space to install the stoppers is also an issue.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a seismic isolation stopper and a seismic isolated building that can prevent excessive deformation during a major earthquake without narrowing the clearance of the seismic isolation layer. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the seismic isolation stopper of the present invention is a seismic isolation stopper that suppresses displacement of a seismic isolation layer provided between an upper structure and a lower structure, and is characterized in that it comprises a displacement suppression section embedded in a retaining wall provided around the upper structure in a position opposite the seismic isolation layer, and a linear member stretched between the upper structure and the displacement suppression section, and when the upper structure moves a predetermined amount relative to the lower structure, the linear member becomes tensed and the displacement suppression section functions.

[0008] According to this invention, since the displacement prevention part is embedded in the retaining wall, only a linear member is placed in the space between the upper structure and the retaining wall. Therefore, the seismic isolation stopper can be placed without narrowing the clearance of the seismic isolation layer. In addition, the displacement prevention part can reliably prevent excessive deformation during a major earthquake.

[0009] The displacement suppressing portion may be formed by laminating a steel plate and a viscoelastic body. By constructing the displacement suppression portion with a simple structure in which steel plates and viscoelastic bodies are stacked in this way, it is possible to reliably suppress the displacement of the upper structure at low cost.

[0010] The seismically isolated building according to the present invention is characterized in that a plurality of the seismic isolation stoppers described above are provided around the upper structure so as to accommodate displacements in different directions.

[0011] According to this invention, the seismic isolation stopper functions to suppress the displacement of the upper structure relative to the lower structure in any direction in a plan view. In addition, because the displacement suppression part is embedded in the retaining wall, a larger clearance can be secured between the upper structure and the retaining wall. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a seismic isolation stopper and a seismic isolated building that can prevent excessive deformation during a major earthquake without narrowing the clearance of the seismic isolation layer. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic plan view of a base-isolated building according to an embodiment of the present invention. [Figure 2] 1 is a schematic side view of a base-isolated building according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic side view showing a state in which the upper structure has relatively moved from the state in FIG. 2. [Figure 4] 10 is a graph showing the difference in seismic isolation layer displacement depending on whether or not a seismic isolation stopper is present. [Figure 5] 10 is a graph showing the hysteresis curve of a seismic isolation stopper. DETAILED DESCRIPTION OF THE INVENTION

[0014] A seismic isolation stopper and a seismic isolated building according to an embodiment of the present invention will be described below with reference to FIGS.

[0015] As shown in Figures 1 and 2, a base-isolated building 1 comprises a substructure 2, a base isolation layer 3 provided above the substructure 2, and an upper structure 4 provided above the base isolation layer 3. The base isolation layer 3 is made up of general laminated rubber, sliding bearings, rolling bearings, etc.

[0016] In plan view, a retaining wall 5 is provided around the upper structure 4 at a predetermined interval. The retaining wall 5 faces the seismic isolation layer 3 horizontally and is formed at a height facing the lower part of the upper structure 4. A space S is formed between the upper structure 4 and the retaining wall 5. The space S becomes a clearance when the upper structure 4 moves relative to the lower structure 2 during an earthquake. In this embodiment, the upper structure 4 is a building that is rectangular in plan view, and the retaining wall 5 is formed around the entire periphery of the upper structure 4.

[0017] Seismic isolation stoppers (hereinafter referred to as "stoppers") 10 are provided between the upper structure 4 and the retaining wall 5. The stoppers 10 are provided at one location on each side of the retaining wall 5, which is rectangular in plan view. Note that the stoppers 10 may be provided at two or more locations on each side of the retaining wall 5. Furthermore, depending on the conditions of the seismically isolated building 1, the stoppers 10 may be provided on only some of the sides of the retaining wall 5.

[0018] The stopper 10 includes a displacement restraining portion 11 embedded in the retaining wall 5, and a wire (linear member) 12 stretched between the displacement restraining portion 11 and the upper structure 4.

[0019] The displacement prevention section 11 is formed by alternately stacking steel plates 13 and viscoelastic bodies 14 such as rubber. In this embodiment, four steel plates are arranged vertically, and a viscoelastic body 14 is disposed between adjacent steel plates 13, 13. In other words, three viscoelastic bodies 14 are arranged vertically. The steel plates 13 and the viscoelastic bodies 14 are formed in a rectangular shape when viewed from above. The number of stacked steel plates 13 and viscoelastic bodies 14, as well as the area when viewed from above and the thickness in the vertical direction, may be set appropriately depending on the conditions of the seismically isolated building 1. Similarly, the material properties of the viscoelastic bodies 14 may be set appropriately depending on the conditions of the seismically isolated building 1.

[0020] Of the steel plates 13, two steel plates 13A, 13A at the center in the height direction protrude slightly toward the space S beyond the surface 5S of the retaining wall 5, and these protruding portions are configured as connecting parts 15 with the wires 12. There is no particular restriction on the method of connecting the wires 12 and the steel plates 13A at the connecting parts 15, as long as the connecting parts 15 will not break even in the event of a major earthquake.

[0021] The length L of the wires 12 is set to a length that allows the upper structure 4 to bend when it is in the reference position, and is also set to a length that puts one of the wires 12 in a tensioned state when the upper structure 4 is displaced a predetermined amount horizontally relative to the lower structure 2, as shown in Figure 3. It is preferable that the length L of the wires 12 of the stoppers 10, 10 that face each other across the seismically isolated building 1 be set to the same length, but the lengths may differ slightly. Note that when one of the wires 12 is in a tensioned state as shown in Figure 3, the upper structure 4 is configured to ensure a predetermined clearance without colliding with the retaining wall 5 on the opposite side.

[0022] The displacement suppression portion 11 of the stopper 10 is embedded in the retaining wall 5, and when one of the wires 12 is in a tensioned state as shown in FIG. 3, a horizontal tensile force acts on the steel plate 13A. When this tensile force is transmitted to the viscoelastic body 14, the viscoelastic body 14 undergoes shear deformation, thereby absorbing the energy. In other words, the displacement suppression portion 11 acts as a damper, and as a result, it has the function of suppressing the shaking of the base-isolated building 1. Note that there is no particular restriction on the method of fixing the displacement suppression portion 11, as long as it can maintain its fixed state to the retaining wall 5 when a horizontal force is applied.

[0023] The function and effect of the stopper 10 of this embodiment will be described. The stopper 10 of this embodiment has the function of preventing the upper structure 4 from colliding with the retaining wall 5 when excessive deformation occurs in the seismic isolation layer 3 due to long-period pulse seismic motion, etc., and of suppressing the shaking of the seismically isolated building 1.

[0024] Under normal circumstances, the seismically isolated building 1 and stopper 10 are maintained in the state shown in Figure 2. During an earthquake, the upper structure 4 moves horizontally relative to the lower structure 2 via the seismic isolation layer 3, as shown in Figure 3. As a result, when the upper structure 4 moves a predetermined amount relative to the lower structure 2, one of the wires 12 becomes tensed.

[0025] If the upper structure 4 attempts to move further from the state shown in Figure 3 in the direction opposite to the tensioned wire 12, the displacement suppression part 11 connected to the tensioned wire 12 will function. Specifically, a horizontal force is applied to the viscoelastic body 14 via the steel plate 13A, and the viscoelastic body 14 will absorb energy by shear deformation, suppressing the horizontal displacement of the upper structure 4. If the upper structure 4 moves in the direction opposite to the state shown in Figure 3, the stopper 10 on the opposite side will function.

[0026] By configuring the stopper 10 in this way, it is only necessary to arrange the wire 12 in the space S, and the space S can be secured as a maximum clearance for the upper structure 4. In other words, excessive deformation can be suppressed without increasing the clearance of the seismically isolated building 1.

[0027] (Example) The results of an analysis verifying the effect of the stopper 10 of this embodiment will be described. 4 and 5 show the difference in the displacement of the seismic isolation layer with and without the stopper 10 based on an analysis of a one-mass model, and the hysteresis characteristics of the stopper 10 using a viscoelastic body.

[0028] The single mass model had a building mass of 30,000t, a period of 4.0s for the seismic isolation layer, and damping of 20% for the seismic isolation layer.The analysis was performed under the condition that the building was forcibly displaced in one direction and then rapidly released, resulting in a displacement of 750mm due to free vibration of the building. Therefore, the analysis results without stoppers show that the maximum displacement of the seismic isolation layer is 750 mm (dashed line in Figure 4). In addition, the stopper was set so that the wire would be effective from 600 mm and the stopper load would be generated, and the viscoelastic material would deform by about 100 mm to control the displacement of the seismic isolation layer.

[0029] As shown in Figure 4, when the stopper is present, the displacement of the seismic isolation layer is approximately 700 mm, which is approximately 50 mm less than when there is no stopper (thick line in Figure 4). Furthermore, as shown in Figure 5, when a viscoelastic body is used, the load-deformation relationship of the stopper follows a hysteresis loop, and it can be seen that energy absorption can be expected.

[0030] The stopper 10 of this embodiment comprises a displacement prevention part 11 embedded in a retaining wall 5 located around the upper structure 4 at a position opposite the seismic isolation layer 3, and a wire 12 stretched between the upper structure 4 and the displacement prevention part 11, and is configured so that when the upper structure 4 moves a predetermined amount relative to the lower structure 2, the wire 12 becomes taut and the displacement prevention part 11 functions.

[0031] Because of this configuration, the stopper 10 can be installed without increasing the space (clearance) S around the upper structure 4 (seismic isolation layer 3). In addition, there is no need to secure a space in the space S for installing the stopper 10.

[0032] Furthermore, the displacement at which the stopper 10 begins to act can be set by the length of the wire 12, and the stopper displacement can be easily changed later simply by replacing the wire 12.

[0033] The displacement prevention portion 11 is constructed by laminating the steel plate 13 and the viscoelastic body 14, and is therefore expected to absorb collision energy.

[0034] Furthermore, by adjusting the material properties of the viscoelastic body 14, and the thickness, area, and number of layers of the steel plate 13 and the viscoelastic body 14, stoppers 10 with various properties can be easily installed.

[0035] Furthermore, by providing a plurality of stoppers 10 around the upper structure 4 so as to correspond to displacements in different directions, it becomes possible to set any desired damping characteristic value for the upper structure 4 more flexibly.

[0036] The above embodiment can be modified as appropriate within the scope of the present invention. For example, in the above embodiment, the upper structure 4 has been described as having a rectangular shape in plan view, but the shape of the upper structure 4 (base-isolated building 1) is arbitrary. In this case, the installation position and damping characteristics of the stopper 10 may be arbitrarily set according to the shape of the base-isolated building 1.

[0037] In addition, in this embodiment, the displacement restraining portion 11 has a structure in which the steel plate 13 and the viscoelastic body 14 are stacked in the vertical direction, but the configuration of the displacement restraining portion 11 is not limited to this as long as it has a structure that can absorb energy. [Explanation of symbols]

[0038] 1. Earthquake-isolated buildings 2 Undercarriage 3. Seismic isolation layer 4 Superstructure 5. Retaining walls 10 Stopper (seismic isolation stopper) 11 Displacement prevention section 12 Wire (linear components) 13,13A steel plate 14 Viscoelastic materials

Claims

1. A seismic isolation stopper that suppresses displacement of a seismic isolation layer provided between an upper structure and a lower structure, a displacement suppression unit embedded in a retaining wall provided around the upper structure at a position facing the seismic isolation layer; a linear member bridged between the upper structure and the displacement suppression part, When the upper structure moves relative to the lower structure by a predetermined amount, the linear member is tensed and the displacement suppression unit functions, The displacement suppression portion is formed by laminating a steel plate and a viscoelastic body, the linear member is connected to the steel plate, A seismic isolation stopper characterized in that the displacement suppression portion acts as a damper when the linear member is under tension.

2. A seismically isolated building, characterized in that a plurality of seismic isolation stoppers according to claim 1 are provided around the periphery of the upper structure so as to accommodate displacements in different directions.

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