JP2022161982A - Multistory base insulation building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multistory base isolation building capable of effectively coping with a small and medium scale earthquake vibration of high occurrence frequency to an excessive earthquake vibration exceeding a normal design level.

SOLUTION: A multilayer base isolation building 1A, which is one 1A provided with a plurality of base isolation layers 4, is configured by connecting a lower structure 2, a lower base isolation layer 40, an intermediate structure 31, an intermediate base isolation layer 50, and an upper structure 32 from the lower side to the upper side. Either one base isolation layer 40 of the lower base isolation layer 40 and the intermediate base isolation layer 50 has a horizontal rigidity set smaller than that of the other base isolation layer 50 and is provided with a rigidity imparting mechanism 43 for increasing the horizontal rigidity of the one base isolation layer 40 in accordance with a deformation of the one base isolation layer 40, and the other base isolation layer 50 is deformed in a state where the horizontal rigidity of the one base isolation layer 40 is increased by the rigidity imparting mechanism 43 when an earthquake occurs.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a multi-story base-isolated building having a plurality of base-isolation layers.

Seismic isolation buildings are used to suppress the effects of seismic motion on buildings. In the Kumamoto earthquake that occurred in 2016, etc., unexpectedly large ground motions that greatly exceeded the normal design level (design level in accordance with the Building Standards Act) were observed. Even in a base-isolated building, if it receives excessive seismic motion, there is a possibility that damage such as collision with the retaining wall installed around the base-isolated building and damage to the seismic isolation members installed in the base-isolated building will occur. There is

On the other hand, for example, Patent Document 1 discloses a base isolation layer, a lower structure supported by the base isolation layer, and an intermediate isolation structure provided on the lower structure and having a lower horizontal rigidity than the base isolation layer. A seismically isolated building is disclosed comprising a seismic layer and a superstructure supported by an intermediate seismic isolation layer. In this seismic isolation building, by providing a plurality of seismic isolation layers, each seismic isolation layer can absorb seismic energy, so that it is possible to cope with a larger seismic motion.
In the configuration disclosed in Patent Document 1, the intermediate seismic isolation layer provided in the middle part of the building in the vertical direction is different from a normal seismic isolation layer (foundation seismic isolation layer) provided only in the lowest layer of the building. High-order vibrations that do not occur in buildings may occur. This high-order vibration increases the acceleration in the surrounding layers located above and below the seismic isolation layer even at a normal design level, which may cause overturning of furniture and fixtures in the building. Elevators installed in seismically isolated buildings automatically stop when acceleration exceeding a predetermined level occurs. Due to the increase in acceleration in the seismic isolation layer and its surrounding layers, the elevator may stop even if the earthquake motion does not stop the elevator in a normal seismic isolated building, and it takes time to restore the elevator.

Further, for example, Patent Document 2 discloses a structure composed of a plurality of structures stacked via an intermediate seismic isolation layer, a bottom seismic isolation layer that supports the structure, and a structure provided in the intermediate seismic isolation layer. , and a stiffening device such as a damper for fixing or unlocking the intermediate seismic isolation layer. In such a configuration, during an earthquake, the intermediate seismic isolation layer is fixed or released to change the natural period of the vibration system of the seismic isolation structure. This makes the natural period of the seismic isolation structure different from the vibration period of the seismic motion to prevent resonance and reduce the acceleration response and deformation amount response of the structure.
In the configuration disclosed in Patent Document 2, fixing or releasing of fixing of the intermediate seismic isolation layer is performed by a stiffening device such as a damper. For this reason, in the case of an excessive seismic motion that exceeds the normal design level, the fixing or unfixing of the intermediate seismic isolation layer by the stiffening device may not be performed as intended at the time of design, and damage may occur to the building. For this reason, it is desirable to more reliably prevent damage from excessive seismic motion.

Further, Patent Document 3 includes a lower seismic isolation layer and an upper seismic isolation layer provided between a lower structure and an upper structure on the foundation side, and the upper seismic isolation layer includes a tilt sliding device and a damping device. A configuration consisting of is disclosed.
In the configuration disclosed in Patent Document 3, if the upper seismic isolation layer is designed to prevent slipping at a normal design level, the lower seismic isolation layer deforms first in the case of excessive seismic motion exceeding the normal design level. reach the limit. As a result, there is a possibility that damage such as collision with the retaining wall provided around the base isolated building and destruction of the base isolation members provided in the base isolated building may occur.

JP 2013-104231 A JP 2014-80794 A JP 2017-71909 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multi-storied base-isolated building capable of effectively coping with seismic motions ranging from frequently occurring small and medium-sized seismic motions to excessively large seismic motions exceeding a normal design level.

The present inventors have developed a seismic isolation building that can reduce the seismic load applied to the building, whether it is a seismic motion at a level considered in normal design or an excessive seismic motion that exceeds the normal design level. From the lower side to the upper floor side, the lower seismic isolation layer, the intermediate structure, the intermediate seismic isolation layer, and the upper structure are constructed in that order. In comparison, by making the horizontal rigidity lower and installing a rigidity imparting mechanism in the lower seismic isolation layer, only the lower seismic isolation layer exhibits the seismic isolation mechanism at a normal seismic motion level, while an intermediate seismic isolation is provided at an excessive seismic motion level. The present invention has been made by paying attention to the point that the seismic isolation effect can be exhibited against various seismic motions by making only the layer exhibit the seismic isolation mechanism.
In order to solve the above problems, the present invention employs the following means.
That is, the multi-storied base isolated building of the present invention is a multi-storied base isolated building provided with a plurality of seismic isolation layers. , an intermediate seismic isolation layer, and a second upper structure are connected to each other, and one of the lower seismic isolation layer and the intermediate seismic isolation layer has a horizontal rigidity equal to that of the other seismic isolation layer A rigidity imparting mechanism is provided which is set smaller and which increases the horizontal rigidity of the one seismic isolation layer as the one seismic isolation layer is deformed, and the other seismic isolation layer is provided with the rigidity imparted when an earthquake occurs. The one seismic isolation layer is deformed in a state in which the horizontal rigidity is increased by a mechanism.
According to such a configuration, the isolation layer with the smaller horizontal rigidity of the lower base isolation layer and the middle base isolation layer is used as long as the level of the external force acting on the multi-story base isolation building due to earthquake motion does not exceed a certain level. Deformation occurs in the seismic layer, and seismic isolation performance is exhibited. At this time, of the lower base isolation layer and the middle base isolation layer, deformation is suppressed in the other base isolation layer with higher horizontal rigidity, and deformation is applied only to the one base isolation layer with lower horizontal rigidity, demonstrating the seismic isolation effect. be done.
When the level of external force due to seismic motion exceeds a certain level, the one of the lower seismic isolation layer and the middle seismic isolation layer, which has the smaller horizontal stiffness, will be affected by the stiffness imparted by the stiffness imparting mechanism. The horizontal rigidity of the seismic isolation layer increases. This increase in horizontal stiffness limits the increase in deformation above a certain level in one seismic isolation layer. Then, the seismic isolation effect exhibited by one seismic isolation layer is suppressed. As a result, the horizontal rigidity of the other seismic isolation layer, which originally had high horizontal rigidity, was increased to limit deformation, and as a result, the seismic load due to the seismic motion was transmitted to the top and bottom of the other seismic isolation layer. be done. As a result, deformation occurs in the other seismic isolation layer, and the seismic isolation performance can be exhibited.
In this way, when the external force level is small, the seismic isolation performance is mainly exhibited by the seismic isolation layer having the smaller horizontal rigidity. After the external force level increases and the horizontal rigidity of one seismic isolation layer rises, the seismic isolation performance is mainly exhibited in the other seismic isolation layer with relatively low horizontal rigidity.
As a result, it is possible to provide a multi-story base-isolated building that can effectively cope with both excessive seismic motions and frequently occurring small and medium-sized seismic motions.

In one aspect of the present invention, in the multi-story base-isolated building of the present invention, the stiffening mechanism includes a linear stiffening type stopper, a stopper with a buffer material, a damper with a hardening mechanism, and a curved surface slide with a hardening mechanism. Any one of the supports, or a combination of two or more.
According to such a configuration, when the displacement in one of the seismic isolation layers with low horizontal stiffness exceeds the displacement assumed at the normal design level, the rigidity is imparted by the rigidity imparting mechanism, and the one seismic isolation layer is The horizontal stiffness of the layer can be increased. This makes it possible to suppress deformation of one seismic isolation layer beyond a certain level and concentrate the deformation on the other seismic isolation layer.

In another aspect of the present invention, in the multi-story seismic isolation building of the present invention, the other seismic isolation layer comprises one or two of sliding bearings, dampers with lock mechanisms, friction dampers, steel dampers, and shear pins. It consists of a combination of more than one type and a seismic isolation rubber bearing.
According to this configuration, when an excessive seismic motion exceeding the normal design level occurs, after the horizontal rigidity of one seismic isolation layer is increased, the seismic load acting on the other seismic isolation layer exceeds the load threshold. Then, the constraint of the other seismic isolation layer is released to allow deformation. Further input of seismic load can be suppressed by permitting deformation of the other seismic isolation layer.

According to the present invention, it is possible to provide a multi-story base-isolated building capable of effectively coping with seismic motions ranging from frequently occurring small and medium-sized seismic motions to excessively large seismic motions exceeding a normal design level.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows schematic structure of the multiple-story base-isolation building which concerns on embodiment of this invention. FIG. 2 is a front view showing a state in which only the lower base isolation layer is deformed in the multi-story base isolation building of FIG. 1; FIG. 2 is a front view showing a state in which deformation of the lower seismic isolation layer is constrained and the middle seismic isolation layer is deformed in the multiple-storied seismic isolation building of FIG. 1 ; It is a figure which shows the vibration model for verification for the multiple-story base-isolated building of FIG. It is a figure which shows the vibration model for the conventional multilayer seismic isolation devices. It is a verification result (ordinary design seismic motion level: comparison of the maximum interlayer deformation amount of each floor) of the present invention and the conventional type multi-story base-isolated building. It is a verification result (ordinary design seismic motion level: comparison of the maximum response acceleration of each floor) of the multistory base-isolated building by this invention and a conventional type. It is the verification result (excessive seismic motion level: comparison of the maximum interlayer deformation amount of each floor) of the multi-story base-isolated building by this invention and a conventional type. It is the verification result (excessive ground motion level: comparison of the maximum response acceleration of each floor) of the multistory base-isolated building by this invention and a conventional type. 1 is a schematic configuration diagram of a multi-story base-isolated building according to a first modified example of the embodiment of the present invention; FIG. FIG. 11 is a diagram showing a verification vibration model for the multi-story base-isolated building of the first modified example of FIG. 10 ; It is the verification result of the multistory base-isolated building by the 1st modification and a conventional type (ordinary design seismic motion level: comparison of the maximum interlayer deformation amount of each floor). It is the verification result of the multistory base-isolated building by the 1st modification and a conventional type (normal design seismic motion level: comparison of the maximum response acceleration of each floor). It is the verification result (excessive seismic motion level: comparison of the maximum inter-story deformation amount of each floor) of the multi-story base-isolated building by the 1st modification and a conventional type. It is the verification result (excessive seismic motion level: comparison of the maximum response acceleration of each floor) of the multistory base-isolated building by the 1st modification and a conventional type. FIG. 5 is a schematic configuration diagram of a multi-story base-isolated building according to a second modified example of the embodiment of the present invention; FIG. 11 is a schematic configuration diagram of a multi-story base-isolated building according to a third modified example of the embodiment of the present invention; FIG. 11 is a schematic configuration diagram of a multi-story base-isolated building according to a fourth modified example of the embodiment of the present invention;

The present invention relates to a multi-storied base-isolated building having a plurality of base-isolation layers. In addition to setting the horizontal rigidity of either the lower base isolation layer or the middle base isolation layer to be smaller than the horizontal rigidity of the other base isolation layer, It is characterized by having a rigidity imparting mechanism that increases horizontal rigidity as deformation increases.
An embodiment of the present invention is a two-story base isolation building consisting of a lower base isolation layer and an intermediate base isolation layer. are installed (Figs. 1 to 9). In the first modification, a damper 45 with a hardening mechanism is installed as a rigidity imparting mechanism in the lower seismic isolation layer, and an oil damper 54 with a relief mechanism for seismic isolation structure and an oil damper 55 with a lock mechanism are installed in the middle seismic isolation layer. (Figs. 10-15). In addition, in the second modification, a medium-friction sliding bearing 46 (with a small coefficient of friction) is installed in the lower seismic isolation layer, and a high-friction sliding bearing 56 is installed in the middle seismic isolation layer. The lower seismic isolation layer slips under a lower load than the middle seismic isolation layer, and horizontal deformation occurs early (Fig. 16).
The third modification is a multi-story base-isolated building in which a lower seismic isolation layer is installed on the lower side of the first floor and an intermediate seismic isolation layer is installed on the upper side of the first floor (Fig. 17).
The fourth modification differs from each of the above-described embodiments in that the intermediate seismic isolation layer has lower horizontal rigidity than the lower seismic isolation layer, and a stopper 43E is installed as a rigidity imparting mechanism in the intermediate seismic isolation layer. (Fig. 18).

EMBODIMENT OF THE INVENTION Hereafter, with reference to an accompanying drawing, the form for implementing the multistory base-isolated building by this invention is demonstrated based on drawing.
FIG. 1 shows a front view showing a schematic configuration of a multi-story base-isolated building according to an embodiment of the present invention. FIG. 2 is a front view showing a deformed lower base isolation layer in the multi-story base isolation building of FIG. FIG. 3 is a front view showing a state in which deformation of the lower seismic isolation layer is constrained and the intermediate seismic isolation layer is deformed in the multi-storied seismic isolation building of FIG.
As shown in FIG. 1, a multi-story base isolation building 1A includes a substructure 2, a building body 3, and a plurality of base isolation layers 4. As shown in FIG.
The substructure 2 is supported by the ground. The lower structure 2 includes a foundation floor slab 21 positioned in a horizontal plane and a retaining wall 22 rising upward from the outer peripheral portion of the foundation floor slab 21 .
The building body 3 includes an intermediate structure (first upper structure) 31 forming a lower floor, and an upper structure (second upper structure) 32 forming an upper floor. In the present embodiment, for example, the intermediate structure 31 has a smaller height dimension in the vertical direction than the upper structure 32 and has a smaller number of floors.
A lower seismic isolation layer 40 and an intermediate seismic isolation layer 50 are provided as the plurality of seismic isolation layers 4 . The lower seismic isolation layer 40 is provided at the lowest part of the multi-storied seismic isolated building 1A, and is provided between the base floor slab 21 and the intermediate structure 31 . The intermediate seismic isolation layer 50 is provided in the vertical intermediate portion of the multi-story seismic isolated building 1A, and is provided between the intermediate structure 31 and the upper structure 32 .
In this way, in the multi-story base-isolated building 1A, the lower structure 2, the lower base isolation layer 40, the intermediate structure 31, the intermediate base isolation layer 50, and the upper structure 32 are connected from the bottom to the top. configured.

The lower seismic isolation layer 40 includes a plurality of seismic isolation rubber bearings 41 , an oil damper 42 and a rigidity imparting mechanism 43 .
The seismic isolation rubber bearing 41 includes a laminated rubber portion 41c in which steel plates and rubber layers are alternately laminated in the vertical direction between upper and lower plates 41a and 41b.
One end 42 a of the oil damper 42 is fixed to the base floor slab 21 of the lower structure 2 , and the other end 42 b is fixed to the lower surface of the intermediate structure 31 . The oil damper 42 has a damper body 42c between one end 42a and the other end 42b.
As shown in FIG. 2, when the intermediate structure 31 is horizontally displaced with respect to the lower structure 2 due to earthquake motion, the upper plate 41a and the lower plate 41b of the seismic isolation rubber bearing 41 are relatively displaced in the horizontal direction. Then, the rubber layer of the laminated rubber portion 41c is elastically deformed, and the oscillation of the intermediate structure 31 and the upper structure 32 is lengthened. At this time, in the oil damper 42, the damper main body 42c expands and contracts. This dampens the horizontal relative displacement of the intermediate structure 31 with respect to the lower structure 2 .

The rigidity imparting mechanism 43 increases the horizontal rigidity of the lower seismic isolation layer 40 . The rigidity imparting mechanism 43 increases the horizontal rigidity of the lower base isolation layer 40 according to the amount of deformation of the lower base isolation layer 40 caused by the horizontal displacement of the intermediate structure 31 with respect to the lower structure 2 due to earthquake motion. Let The stiffening mechanism 43 is a linear stiffening type stopper, a stopper with cushioning material, a damper with a hardening mechanism, or a curved sliding bearing with a hardening mechanism, or a combination of two or more. As the stiffening mechanism 43, other than this, a fall prevention chain for a bridge, a hardening phenomenon of a laminated rubber bearing, or the like can be used. Therefore, the rigidity imparting mechanism increases the horizontal rigidity of the seismic isolation layer not only by the spring rigidity of the stopper or the like, but also by the resistance due to the viscous damping of the damper or the like with the hardening mechanism. Specifically, in this embodiment, a stopper 44 is provided as the rigidity imparting mechanism 43 . This stopper 44 is a linear stiffening type stopper or a cushioned stopper. More specifically, as the stopper 44, a collision buffer material such as a fender, a steel damper, a restoring rubber, or the like can be used. A stopper 44 is provided on the retaining wall 22 of the lower structure 2 . The stopper 44 is provided with a gap S in the horizontal direction between it and the outer surface of the intermediate structure 31 under normal conditions (a state in which no seismic motion occurs). As shown in FIG. 3, when the intermediate structure 31 is horizontally displaced by an amount equal to or larger than the gap S due to the seismic motion and collides with the stopper 44, the intermediate structure 31 is restrained from being displaced beyond a certain level. This substantially increases the horizontal rigidity of the lower base isolation layer 40 .
Such a lower seismic isolation layer 40 is set to have a horizontal rigidity smaller than that of the intermediate seismic isolation layer 50 . More specifically, before the lower seismic isolation layer 40 is imparted with rigidity by the rigidity imparting mechanism 43, the horizontal rigidity due to the plurality of seismic isolation rubber bearings 41 and the oil dampers 42 is smaller than that of the intermediate seismic isolation layer 50. is set.

As shown in FIG. 1 , the intermediate seismic isolation layer 50 includes a plurality of seismic isolation rubber bearings 51 and restraining members 52 .
The seismic isolation rubber bearing 51 includes a laminated rubber portion 51c in which steel plates and rubber layers are alternately laminated in the vertical direction between upper and lower plates 51a and 51b. In the seismic isolation rubber bearing 51, when the upper structure 32 is displaced horizontally with respect to the intermediate structure 31 due to seismic motion, the upper plate 51a and the lower plate 51b are displaced horizontally. As a result, the rubber layer of the laminated rubber portion 51c is elastically deformed, and the vibration of the upper structure 32 is lengthened.
The restraining member 52 restrains the horizontal relative displacement of the upper structure 32 with respect to the intermediate structure 31 when the seismic load acting on the intermediate seismic isolation layer 50 is equal to or less than a predetermined load threshold. The restraining member 52 releases the restraint of the horizontal relative displacement of the upper structure 32 with respect to the intermediate structure 31 when the seismic load acting on the intermediate seismic isolation layer 50 exceeds a predetermined load threshold. Here, the load threshold for releasing the restraint of the displacement of the upper structure 32 by the restraining member 52 causes deformation in either the lower seismic isolation layer or the middle seismic isolation layer, and the seismic isolation effect is exhibited stably. As much as possible, it is preferable to make the seismic load equivalent to the impact of the intermediate structure 31 against the stopper 44 . As such a restraining member 52, any one of a slide bearing, a seismic isolation steel damper, an oil damper with a locking mechanism, a friction damper, and a shear pin, or a combination of two or more of them is used. In this embodiment, an elastic sliding bearing 53 is provided as the restraining member 52 . The elastic sliding bearing body 53 is designed to prevent the bearing body from sliding against the sliding plate when the seismic load acting on the intermediate seismic isolation layer 50 exceeds a predetermined load threshold, that is, when the intermediate structure 31 collides with the stopper 44 . The coefficient of friction is set so that it begins to slide.

Next, the operation of the multi-story base-isolated building 1A will be described.
First, at a normal design seismic motion level, as shown in FIG. Of the lower base isolation layer 40 and the intermediate base isolation layer 50, only the lower base isolation layer 40, which has a small horizontal rigidity, is deformed and exhibits the base isolation performance. At this time, deformation is suppressed in the middle base isolation layer 50 having a higher horizontal rigidity than the lower base isolation layer 40 .
Next, at an excessive seismic motion level exceeding the normal design level, as shown in FIG. By colliding with 44, deformation in the horizontal direction greater than or equal to the dimension of the gap S (see FIG. 1) is constrained. As a result, the horizontal rigidity of the lower seismic isolation layer 40 increases, and the seismic isolation effect exhibited by the lower seismic isolation layer 40 is limited. When the deformation of the lower base isolation layer 40 is restrained to a certain degree or more in this way, the shear force due to the external force (earthquake load) due to the seismic motion is transmitted to the layers above the lower base isolation layer 40 . When the seismic load acting on the intermediate seismic isolation layer 50 exceeds the load threshold, the elastic sliding support 53 slides, and the restraint by the restraint member 52 is released. As a result, horizontal relative displacement occurs between the intermediate structure 31 and the upper structure 32 above and below the intermediate isolation layer 50 , and the intermediate isolation layer 50 is deformed. As a result, the intermediate seismic isolation layer 50 exhibits seismic isolation performance.
As described above, when the external force level due to the seismic motion is small, the lower seismic isolation layer 40 having a small horizontal rigidity mainly exhibits the seismic isolation performance. After the external force level due to seismic motion increases and the displacement of the lower seismic isolation layer 40 is constrained to a certain level or more, the seismic isolation performance is mainly exhibited by the intermediate seismic isolation layer 50 having high horizontal rigidity.

By the way, when residual displacement occurs in the intermediate seismic isolation layer 50 after an earthquake, if the layer (lower seismic isolation layer 40) that precedes the deformation as described above is located below, a jack or the like will be used for restoration in order to eliminate the residual displacement. When the intermediate base isolation layer 50 is moved by a mechanism to adjust its position, the reaction force may cause the lower base isolation layer 40 to move. In order to suppress this, the lower seismic isolation layer 40 requires a seismic isolation layer fixing mechanism. Various fixing mechanisms are conceivable, but as one example, when moving the intermediate seismic isolation layer 50 with a jack or the like, a sufficiently hard block material is sandwiched between the retaining wall 22 and the intermediate structure 31 to secure the intermediate structure. It suffices to fix the structure 31 horizontally.

(Verification by seismic response analysis of the multi-story base-isolated building of the present invention, Part 1)
Here, a simulation analysis was performed with respect to the configuration as described above.
FIG. 4 is a diagram showing a vibration model used for simulation analysis of the multi-layer seismic isolation device of FIG. FIG. 5 is a diagram showing a vibration model of a conventional multi-layer seismic isolation structure used for comparison when performing simulation analysis on a multi-layer seismic isolation device.
For the simulation analysis, the 21-mass point model of the multi-story base-isolated building of this embodiment was used as the vibration model M1. At this time, the seismic isolation layer was set to the layer between the foundation and the 1st floor and the layer corresponding to the 4th floor. For comparison, the case of a conventional multi-layer seismic isolation structure that does not include the rigidity imparting mechanism 43 and the restraining member 52 and simply has two seismic isolation layers of the same structure above and below as shown in FIG. A 21-mass point model of a 20-story multi-story base-isolated building was used as the vibration model M2.
For each of the vibration models M1 and M2, the El Centro NS50kine standardized wave, which is used at the normal design level, was adopted as the normal design seismic motion level, and the Kumamoto Earthquake Nishihara Komorihara, Nishihara Village, Kumamoto Earthquake as an excessive seismic motion level that occurs extremely rarely. adopted waves. Interlaminar deformation and acceleration in each layer were obtained by simulation as seismic response when each earthquake was input.

FIG. 6 is a diagram showing interlayer deformation in each layer when an El Centro NS50kine normalized wave is input. FIG. 7 is a diagram showing the acceleration in each layer when the El Centro NS50kine normalized wave is input. FIG. 8 is a diagram showing inter-layer deformation in each layer when the Kumamoto earthquake Nishihara-mura Komori original wave is input. FIG. 9 is a diagram showing the acceleration in each layer when the Kumamoto earthquake Nishihara-mura Komori original wave is input.
As shown in Fig. 6, when the El Centro NS50kine normalized wave used at the normal design level is input, in the vibration model M2 of the conventional multi-layer seismic isolation structure, large deformation occurs in the two layers. In contrast, in the vibration model M1 in this embodiment, the amount of deformation increased only in the lower seismic isolation layer 40 . Further, as shown in FIG. 7, in comparison with the vibration model M2 of the conventional multi-layer seismic isolation structure, in the vibration model M1 of the present embodiment, the intermediate structure between the lower seismic isolation layer 40 and the intermediate seismic isolation layer 50 Each layer of the object 31 has a reduced response acceleration.

Further, as shown in FIG. 8, when the Kumamoto earthquake Nishihara-mura Komori original wave is input, the interlayer deformation of each layer is are almost the same. Therefore, it can be said that the safety of the multi-story base-isolated building 1A in the limit state can be ensured to be equivalent to that of the conventional multi-story base-isolated structure.
As shown in FIG. 9, when the Kumamoto earthquake Nishihara-mura Komori original wave is input, below the intermediate seismic isolation layer 50, the function as a seismic isolation structure is reduced, and the vibration of the conventional multi-layer seismic isolation structure Compared to the model M2, the response acceleration in the vibration model M1 in this embodiment is not reduced. This can be dealt with by the configuration of the first modified example, as will be described later.

According to the multi-story base-isolated building 1A as described above, the multi-story base-isolated building 1A is provided with a plurality of base-isolation layers 4. The object 2, the lower base isolation layer 40, the intermediate structure 31, the intermediate base isolation layer 50, and the upper structure 32 are connected to each other. The intermediate isolation layer 50 is provided with a rigidity imparting mechanism 43 that is set small and increases the horizontal rigidity of the lower seismic isolation layer 40 as the lower seismic isolation layer 40 deforms. The seismic isolation layer 40 is deformed while its horizontal rigidity is increased.
According to such a configuration, when the external force level is small, the lower seismic isolation layer 40 having a small horizontal rigidity mainly exhibits the seismic isolation performance. After the external force level increases and the horizontal rigidity of the lower seismic isolation layer 40 increases, the seismic isolation performance is mainly exhibited in the middle seismic isolation layer 50 having high horizontal rigidity. In this way, when the external force level is small, the lower seismic isolation layer 40 is the only seismic isolation layer 4 that allows deformation, and the acceleration response performance is improved in that range. Also, by limiting the seismic isolation layer 4 that allows deformation to a single layer, it is possible to shorten the time required to restore elevators and the like in the event of a relatively frequent earthquake. Further, when the external force level increases, the deformation of the lower seismic isolation layer 40, which has been allowed to deform, is restricted, and the deformation of the intermediate seismic isolation layer 50, which has been restricted to deformation, is allowed.
In this way, the number of seismic isolation layers 4 that can cope with excessive seismic motion that greatly exceeds the normal design level and that allows deformation at the normal design level is limited to the lower seismic isolation layer 40. It is possible to enhance the seismic isolation performance against earthquakes that occur relatively frequently, and improve the performance of restoring building functions after a disaster.
In addition, since the deformation of the intermediate seismic isolation layer 50 can be limited within the range of the normal design level, the acceleration response can be suppressed lower than that of the conventional multi-layer seismic isolation, and the It is possible to shorten the restoration time after the elevator is damaged.
Furthermore, even if the seismic motion exceeds the normal design level, the intermediate seismic isolation layer 50, which limits the deformation, exerts the seismic isolation function, thereby suppressing the damage of the multi-story seismic isolation building 1A and allowing it to be used continuously. can do.
As a result, it is possible to provide the multi-story base-isolated building 1A that can effectively cope with earthquake motions ranging from frequently occurring small and medium-sized earthquake motions to excessive earthquake motions exceeding the normal design level.

The stiffening mechanism 43 may be any one of a linear stiffening type stopper, a stopper with cushioning material, a damper with a hardening mechanism, and a curved sliding bearing with a hardening mechanism, or a combination of two or more. be.
According to such a configuration, when the displacement of the lower base isolation layer 40 with low horizontal rigidity exceeds the displacement assumed at the normal design level, the rigidity imparting mechanism 43 prevents the lower base isolation layer 40 from being deformed to a certain extent or more. can be suppressed, and the deformation can be concentrated on the intermediate seismic isolation layer 50 .

In the multi-storied seismic isolation building 1A, the intermediate seismic isolation layer 50 is composed of any one of a sliding bearing (elastic sliding bearing 53), a damper with a locking mechanism, a friction damper, a steel damper, and a shear pin, or a combination of two or more. , and a seismic isolation rubber bearing 51.
According to such a configuration, when an excessive seismic motion exceeding a normal design level occurs, after the horizontal rigidity of the lower seismic isolation layer 40 is increased, if the seismic load acting on the middle seismic isolation layer 50 exceeds the load threshold, , the restraint of the intermediate seismic isolation layer 50 is released to allow deformation. By permitting deformation of the intermediate seismic isolation layer 50, further input of seismic load can be suppressed.

(First modification of the embodiment)
It should be noted that the multi-story base-isolated building of the present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications are conceivable within its technical scope.
FIG. 10 shows a diagram showing the configuration of a multi-story base-isolated building in the first modified example of the embodiment of the present invention.
For example, as shown in FIG. 10, a multi-storied seismic isolation building 1B in this modified example has a passive variable attenuation type (displacement It is equipped with an oil damper (damper with a hardening mechanism) 45 with a hardening mechanism (switching type). Further, in the intermediate seismic isolation layer 50B, an oil damper 54 with a relief mechanism for seismic isolation structure and an oil damper with a lock mechanism (a damper with a lock mechanism) 55 are provided as the restraining member 52B instead of the elastic slide bearing 53. I have.
In this modification, the hardening mechanism-equipped oil damper 45 functions as a rigidity imparting mechanism 43B. That is, the load threshold is set so that the intermediate seismic isolation layer 50B is restrained in the range where the oil damper 45 with the hardening mechanism of the lower seismic isolation layer 40B is in the low damping mode. The hardening mechanism-equipped oil damper 45 shifts to the high damping mode when its displacement exceeds the displacement threshold value, that is, when the hardening mechanism-equipped oil damper 45 increases the horizontal rigidity of the lower seismic isolation layer 40B, the intermediate seismic isolation occurs. Set so that the constraint of the layer 50B is released.
The oil damper 55 with a locking mechanism locks the intermediate seismic isolation layer 50B at a normal seismic design level (for example, against an L2 seismic motion), and unlocks the intermediate seismic isolation layer 50B in a range exceeding the seismic motion level. Demonstrate the seismic isolation function.
The method of setting the threshold values of the oil damper 45 with the hardening mechanism and the oil damper 55 with the lock mechanism is determined based on the relationship between the response of the intermediate seismic isolation layer 50B and the lower seismic isolation layer 40B during an earthquake. Therefore, it is preferable to clarify the response relationship between the oil damper 45 with the hardening mechanism and the oil damper 55 with the lock mechanism by seismic response analysis (time history response analysis) or the like.

(Verification by seismic response analysis of the multi-story base-isolated building of the present invention, Part 2)
Here, a simulation analysis was performed with respect to the configuration as described above.
FIG. 11 is a diagram showing a vibration model used when conducting a simulation analysis of the multi-story base-isolated building in the first modified example of the embodiment of the present invention.
The seismic response at this time was a 21-mass point vibration model M3 for a 20-story multi-story base-isolated building according to the first modified example, as shown in FIG. At this time, the seismic isolation layer was set to the layer between the foundation and the 1st floor and the layer corresponding to the 4th floor.
For this vibration model M3, the El Centro NS50kine normalized wave used at the normal design level and the Kumamoto Earthquake Nishihara-mura Komori original wave as excessive seismic motion exceeding the normal design level were input. Interlaminar deformation and acceleration in each layer were obtained by simulation as the seismic response when each original wave was input.

FIG. 12 is a diagram showing interlayer deformation in each layer when an El Centro NS50kine normalized wave is input. FIG. 13 is a diagram showing the acceleration in each layer when the El Centro NS50kine normalized wave is input. FIG. 14 is a diagram showing inter-layer deformation in each layer when the Kumamoto earthquake Nishihara Komori original wave is input. FIG. 15 is a diagram showing the acceleration in each layer when the Kumamoto earthquake Nishihara Komori original wave is input. Here, in FIGS. 12 to 15, the seismic response in the vibration model M2 shown in the above embodiment is used for comparison.
As shown in FIGS. 12 and 13, when the El Centro NS50kine normalized wave used at the normal design level is input, the intermediate isolation layer 50 is constrained, so the behavior is the same as in the above embodiment. The displacement of the seismic layer 50 is suppressed, and the acceleration response is also reduced compared to the conventional multi-layer seismic isolation structure.
Also, as shown in FIGS. 14 and 15, when the Kumamoto earthquake Nishihara-mura Komori original wave is input, the attenuation of the lower seismic isolation layer 40 is switched to high attenuation, and the lock of the middle seismic isolation layer 50 is released. It will switch to a state close to the conventional multi-layered seismic isolation structure. In the above embodiment, as described with reference to FIG. 9, when the Kumamoto earthquake Nishihara-mura Komori original wave is input, below the intermediate base isolation layer 50, the function as a base isolation structure deteriorates. This is improved in this modification as shown in FIG.
As a result, it is possible to obtain an acceleration response performance almost equivalent to that of a conventional multi-layer seismic isolation structure while dealing with large deformation.

(Second modification of the embodiment)
FIG. 16 is a diagram showing the configuration of a multi-story base-isolated building in the second modified example of the embodiment of the present invention.
As shown in FIG. 16, a multi-story base isolation building 1C in this modification includes a medium friction slide bearing 46 in the lower base isolation layer 40C instead of the oil dampers 42 and stoppers 44 in the above embodiment. there is Further, instead of the elastic sliding bearing 53, a high-friction sliding bearing 56 is provided as the restraining member 52C in the intermediate seismic isolation layer 50C.
The medium-friction sliding bearing 46 slips with a lower seismic load than the high-friction sliding bearing 56 does. That is, in this modification, the friction coefficient (static friction coefficient) of the medium friction slide bearing 46 in the lower seismic isolation layer 40 is set smaller than the friction coefficient of the high friction slide bearing 56 in the middle seismic isolation layer 50C.
In such a configuration, deformation of both the lower seismic isolation layer 40C and the intermediate seismic isolation layer 50C is restricted at an external force level that does not exceed the static friction coefficient of the middle friction sliding bearing 46 of the lower seismic isolation layer 40C. When the external force level exceeds the coefficient of static friction of the medium-friction slide bearing 46, the medium-friction slide bearing 46 slides, the lower seismic isolation layer 40C deforms first, and the seismic isolation function is exhibited. In this state, the high-friction slide bearing 56 of the intermediate base isolation layer 50C does not slip, and deformation of the intermediate base isolation layer 50C is restricted. When the external force level further increases and the intermediate structure 31 collides with the stopper 44, further deformation of the lower base isolation layer 40C is constrained, and the horizontal rigidity of the lower base isolation layer 40C increases. Shear forces are transmitted. As a result, the high-friction sliding bearing 56 slips, the intermediate seismic isolation layer 50 deforms, and the seismic isolation function is exhibited.
It goes without saying that this modified example has the same effect as the already described embodiment.

(Third modification of the embodiment)
FIG. 17 is a diagram showing the configuration of a multi-story base-isolated building in the third modified example of the embodiment of the present invention.
As shown in FIG. 17, in a multi-story base isolation building 1D in this modified example, an intermediate structure (second upper structure) 31D between a lower base isolation layer 40D and an intermediate base isolation layer 50D is shall have only
In the configuration of the embodiment shown in FIG. 1, which has already been described, when an excessive seismic motion exceeding the normal design level enters the region where deformation of the lower base isolation layer 40 is restricted, the lower base isolation layer 40 At 40, the seismic isolation function deteriorates. Therefore, the responsiveness of the intermediate structure 31 between the lower seismic isolation layer 40 and the intermediate seismic isolation layer 50 is generally worse than the response of the upper structure 32 above the intermediate seismic isolation layer 50 . On the other hand, in this modified example, the intermediate structure 31D has only one floor, and the floor height is minimized. As a result, it is possible to minimize the number of layers in which the responsiveness deteriorates.
In this modified example, the rigidity imparting mechanism 43D is a stopper fixed to the base floor slab 21 and the intermediate structure 31D, and when the intermediate structure 31 is displaced, the rigidity imparting mechanism 43D moves to the portion facing the lower seismic isolation layer 40D. By coming into contact with the provided displacement restraint member 60, displacement of the intermediate structure 31D above a certain level is restrained. This substantially increases the horizontal rigidity of the lower seismic isolation layer 40D.

Further, particularly in this modified example, the intermediate seismic isolation layer 50D is placed between the upper ends (column heads) of the columns 57 and braces 58 provided on the intermediate structure 31D and the upper structure 32, as in the above embodiment. A seismic isolation rubber bearing 51 and an elastic slide bearing 53 as a restraining member 52 are provided. As a result, the space X provided with the pillars 57 and the braces 58 in the intermediate seismic isolation layer 50D can be used, for example, as a lobby floor.
In this case, the elevator 8 can be provided so as to be suspended from the lowest floor of the upper structure 32 above the intermediate seismic isolation layer 50D. That is, the portion of the elevator 8 located on the intermediate seismic isolation layer 50</b>D can be separated from other structural elements of the intermediate seismic isolation layer 50</b>D and structurally joined to the upper structure 32 . As a result, the entire elevator 8 is displaced integrally with the upper structure 32 during an earthquake, so that the elevator 8 is prevented from being greatly deformed due to displacement due to seismic motion, which is advantageous in terms of disaster prevention planning.
As with the intermediate base isolation layer 50D, the lower base isolation layer 40D is also provided with columns 57 and braces 58, and is provided with base isolation rubber bearings 41 and the like at the upper ends thereof. It can also be used effectively as a space such as a garage or warehouse.

(Fourth modification of the embodiment)
In the above embodiment and the first to third modifications, the horizontal rigidity of the lower seismic isolation layers 40, 40B, 40C, and 40D is lower than that of the middle seismic isolation layers 50, 50B, 50C, and 50D. Not exclusively.
FIG. 18 is a diagram showing the configuration of a multi-story base-isolated building in a fourth modified example of the embodiment of the present invention.
A multi-storied seismic isolation building 1E in this modified example has a configuration in which the middle seismic isolation layer and the lower seismic isolation layer of the embodiment are generally reversed. That is, as shown in FIG. 18, in the multi-story base isolation building 1E, the horizontal rigidity of the middle base isolation layer 50E is set smaller than that of the lower base isolation layer 40E. The multi-story base isolation building 1E includes a base isolation rubber bearing 41 and an elastic slide bearing 48 as a restraint member 47 in a lower base isolation layer 40E. Also, the intermediate seismic isolation layer 50E is provided with an oil damper 42 and a stopper 43E. The stopper 43E is fixed to the intermediate structure 31, and functions as a rigidity imparting mechanism 43E by coming into contact with the displacement restraint member 61 fixed to the upper structure 32. As shown in FIG.
In this modified example, when the external force level is small, the intermediate seismic isolation layer 50E, which has a small horizontal rigidity, mainly exerts seismic isolation performance. When the external force level increases, in the intermediate seismic isolation layer 50E, the stopper 43E collides with the displacement restraining member 61, thereby restraining the deformation in the horizontal direction. This increases the horizontal rigidity of the intermediate seismic isolation layer 50E, and limits the seismic isolation effect exhibited by the intermediate seismic isolation layer 50E. When the seismic load acting on the lower seismic isolation layer 40E exceeds the load threshold, the elastic sliding support 48 provided on the lower seismic isolation layer 40E slides, and the restraint by the restraining member 47 is released. As a result, horizontal relative displacement occurs between the lower structure 2 and the intermediate structure 31 above and below the lower seismic isolation layer 40E, and deformation occurs in the lower seismic isolation layer 40E. As a result, the lower seismic isolation layer 40E exhibits seismic isolation performance.
In this modified example, since the intermediate structure 31 is in a non-seismic isolation state at the normal design level, the seismic isolation performance is lower than in the above-described embodiment and the first to third modified examples. However, when an earthquake occurs and residual displacement occurs in the lower seismic isolation layer 40E, since the lower seismic isolation layer 40E faces the lower structure 2, the residual displacement is resolved and the intermediate structure 31 and the upper structure It is easy to obtain a reaction force for returning the object 32 to the origin. Thus, in this modified example, it is easy to eliminate residual displacement after an earthquake.

(Other modifications)
For example, in the above embodiment and each modified example, two seismic isolation layers 4 are provided, but there is no limit to the number of seismic isolation layers. The number of seismic isolation layers that allow deformation in a range exceeding the level and the threshold of the external force level can be set as appropriate.
Further, in the above-described embodiment and each modified example, a stopper may be added and attached as a fail-safe mechanism for suppressing excessive deformation more than expected even in the seismic isolation layer in which no stopper is provided.
In the multi-story base isolation building having a plurality of base isolation layers according to the above embodiment, one of the lower base isolation layer and the middle base isolation layer has a lower horizontal rigidity than the other base isolation layer. and a rigidity imparting mechanism that increases the horizontal rigidity of the one seismic isolation layer as the one seismic isolation layer deforms. Here, horizontal stiffness includes horizontal strength. That is, in a multi-storied seismic isolation building, either one of the lower seismic isolation layer and the middle seismic isolation layer is set to have a horizontal strength smaller than that of the other seismic isolation layer, and the one seismic isolation layer is provided with a mechanism that increases the horizontal strength of the one seismic isolation layer with the deformation of the other seismic isolation layer, and the other seismic isolation layer is in a state where the horizontal strength of the one seismic isolation layer is increased by the mechanism when an earthquake occurs, It is also possible to surrender or slide.
In addition, in the multi-story seismic isolation building of the above embodiment, the other seismic isolation layer includes any one of sliding bearings, dampers with locking mechanisms, friction dampers, steel dampers, and shear pins, or a combination of two or more of them. Although it is configured in combination with a seismic rubber bearing, the other seismic isolation layer may be formed only of a slide bearing.
In addition to this, it is possible to select the configurations described in the above embodiments or to change them to other configurations as appropriate without departing from the gist of the present invention.

1A, 1B, 1C, 1D, 1E Multistory seismically isolated building 2 Substructure
4 Seismic isolation layer
31, 31D intermediate structure (first upper structure) 32 upper structure (second upper structure)
40, 40B, 40C, 40D, 40E Lower base isolation layer 43, 43B, 43D, 43E Stiffening mechanism 44 Stopper 45 Oil damper with hardening mechanism (damper with hardening mechanism)
46, 48, 53, 56 sliding bearing 55 oil damper with lock mechanism (damper with lock mechanism)
50, 50B, 50C, 50D, 50E Middle seismic isolation layer

Claims (2)

A multi-story base-isolated building comprising a plurality of base-isolated layers,
A lower structure, a lower seismic isolation layer, a first upper structure, an intermediate seismic isolation layer, and a second upper structure are connected from the bottom to the top,
The multi-story base isolation building, wherein the lower base isolation layer and the intermediate base isolation layer are set to have different horizontal rigidity. 2. The multi-storied base isolation building according to claim 1, wherein the horizontal rigidity of said lower base isolation layer is set smaller than the horizontal rigidity of said middle base isolation layer.

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