Search system for seismic isolation layer characteristic, and seismic isolation structure designed using search system for seismic isolation layer characteristic

Abstract

To provide a search system for a seismic isolation layer characteristic capable of searching for a mode of a seismic layer characteristic for a design guideline when a seismic isolation layer is controlled to an optimal state as much as possible upon designing the seismic isolation layer for semi-active control.SOLUTION: A search system for a seismic isolation layer characteristic is to search for a seismic isolation layer characteristic as a purpose to make a response amount smaller when designing the seismic isolation layer of a seismic isolation structure for semi-active control, the characteristics being rigidity. The seismic isolation layer is modeled including a nonlinear spring actively revising a tangential line rigidity. The system comprises a searching section 2 in which a plurality of time indent intervals and a plurality of revised values revising an initial characteristic period and the tangential line rigidity of the seismic isolation layer are to be design parameters, and which determines the rigidity of the seismic isolation structure through searching as revising the design parameters so as to make displacement, speed, or acceleration for an equation of motion expressed by displacement, speed, and acceleration of an upper structure corresponding to a lower structure smaller.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a seismic isolation layer characteristic exploration system that explores the characteristics of a seismic isolation layer with the aim of reducing the response amount when designing the seismic isolation layer of a seismic isolation structure as semi-active control, and to a seismic isolation structure designed using the seismic isolation layer characteristic exploration system. [Background technology]

[0002] In order to reduce the effects of earthquake motion and wind acting on a structure, a seismic isolation layer may be provided in the structure to make it a seismic isolation structure. Such seismic isolation layers are generally designed under the assumption that the mass of the superstructure located above the seismic isolation layer, the restoring force characteristics after deformation of the seismic isolation layer, the damping force characteristics, and other structural parameters are fixed values. In contrast, seismic isolation structures are sometimes designed to respond to earthquake motion and wind in multiple different ways, for example by switching the restoring force characteristics and damping force characteristics depending on the situation, depending on the magnitude of earthquake motion and wind.

[0003] For example, Patent Document 1 discloses a multi-story seismically isolated building with multiple seismic isolation layers. This multi-story seismically isolated building is constructed by connecting a lower structure, a lower seismic isolation layer, an intermediate structure, an intermediate seismic isolation layer, and an upper structure from the bottom to the top. Either the lower seismic isolation layer or the intermediate seismic isolation layer has a horizontal stiffness set smaller than that of the other seismic isolation layer, and is equipped with a stiffness imparting mechanism that increases the horizontal stiffness of one of the seismic isolation layers as one of the seismic isolation layers deforms in a state where the horizontal stiffness of one of the seismic isolation layers has been increased by the stiffness imparting mechanism when earthquake motion occurs. Patent Document 2 discloses a seismically isolated building equipped with a fail-safe mechanism. This seismically isolated building is equipped with a seismic isolation mechanism and a fail-safe mechanism in the upper structure above the seismic isolation mechanism. The fail-safe mechanism includes a tuned mass damper that exerts a tuning effect on at least one of the second or higher natural vibration modes of the seismically isolated building.

[0004] In particular, in recent years, semi-active control seismic isolation and vibration control structures have been proposed and put into practical use, aiming to further improve seismic isolation performance by more actively switching the specifications of the structures as described above. In this regard, Patent Document 3 discloses the following variable structure semi-active seismic isolation system. This variable structure semi-active seismic isolation system includes a variable damper provided between the upper and lower structures of a seismic isolation structure, a sensor or the like that detects the response of the upper and lower structures, a control means having a computer that calculates and outputs a command signal to the variable damper based on the detection signal, and a switching means that switches the damping force based on the command signal. The computer employs a variable structure control method that controls the response deformation and / or response acceleration of the upper structure by switching the damping coefficient of the variable damper based on a switching hyperplane as a control law obtained by using bilinear optimal control theory for a state equation of the entire system that couples a relational equation between the damping force setting value of the variable damper and the damping force actually generated to a state equation of the seismic isolation structure.

[0005] Items to be considered when designing and developing a seismic isolation layer based on semi-active control such as that in Patent Document 3 include the control mechanism ("what" to control) and the control law ("how" to control). With regard to these control mechanisms and control laws, it is difficult to clearly set targets when designing a seismic isolation layer because the response value when the seismic isolation layer is optimally controlled cannot be generally defined. Therefore, the performance evaluation of the designed seismic isolation layer must be relative, such as the degree of improvement over existing control methods. If the form of the characteristics of the seismic isolation layer, such as the layer stiffness, when the seismic isolation layer is controlled in a state close to the optimum, is known in advance when designing the seismic isolation layer, it is possible to set this state close to the optimum as a target value, evaluate the difference between the target value and the design value, and proceed with the design of the seismic isolation layer aiming for the target value so as to reduce this difference. When designing a semi-actively controlled seismic isolation layer, it is desirable to explore the form of the characteristics of the seismic isolation layer, such as its layer rigidity, when the seismic isolation layer is controlled in a state close to optimal, in order to use this as a design guideline. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7125902 [Patent Document 2] Patent Publication No. 2022-68948 [Patent Document 3] Patent No. 4747336 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem that the present invention aims to solve is to provide a seismic isolation layer characteristic exploration system that is capable of exploring the characteristic form of a seismic isolation layer when the seismic isolation layer is controlled in a near-optimal state in order to use as a design guideline when designing a semi-actively controlled seismic isolation layer, and a seismic isolation structure designed using the seismic isolation layer characteristic exploration system. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention employs the following means. That is, the present invention provides a system for searching for characteristics of a seismic isolation layer for the purpose of reducing a response amount when the seismic isolation layer of a seismic isolation structure is designed as a semi-active control, the system being characterized in that the characteristic is stiffness, a substructure and a superstructure of the seismic isolation structure are provided below and above the seismic isolation layer, respectively, the seismic isolation layer is modeled including a nonlinear spring that actively updates tangent stiffness, an initial natural period of the seismic isolation layer for determining initial values ​​of specifications of the seismic isolation layer, a plurality of time intervals at which the tangent stiffness is updated, and an updated value of the tangent stiffness after a time equivalent to each of the time intervals has elapsed, which is provided corresponding to each of the plurality of time intervals, are set as design variables, and the system is further characterized in that the system includes a searching unit that determines the stiffness of the seismic isolation layer by searching while updating the design variables so that the displacement, the velocity, or the acceleration is reduced in an equation of motion expressed by the displacement, the velocity, and the acceleration of the superstructure relative to the substructure. According to the above-mentioned configuration, the seismic isolation layer is modeled including a nonlinear spring that actively updates the tangent stiffness. In the seismic isolation layer that performs such semi-active control, the design variables of the seismic isolation layer include the initial natural period of the seismic isolation layer, a plurality of time intervals at which the tangent stiffness is updated, and an updated value of the tangent stiffness after a time equivalent to the time interval has elapsed, which is provided corresponding to each of the plurality of time intervals. When the initial natural period of the seismic isolation layer is determined, the initial value of the tangent stiffness can be determined by determining the initial values ​​of the seismic isolation layer. After the first time interval among the plurality of time intervals has elapsed, a new tangent stiffness can be set and updated for the initial value of the tangent stiffness based on the updated value after the time interval has elapsed. After that, after the next time interval has elapsed, a new tangent stiffness can be set and updated for the tangent stiffness updated as described above based on the updated value after the time interval has elapsed. In this way, the initial natural period of the seismic isolation layer, the multiple time intervals, and the multiple update values ​​are used as design variables to define the change in tangential stiffness over time. The search unit searches for the above design variables while updating their values ​​so that the displacement, velocity, or acceleration, i.e., the response amount, is reduced in the equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure, and determines the stiffness of the seismic isolation layer. In this way, the initial natural period of the seismic isolation layer, the multiple time intervals, and the multiple update values ​​are used as design variables to search for the design variable values ​​that reduce the response amount, thereby searching for the time and how to control the stiffness to improve the response. Therefore, it becomes easier to find the form of the story stiffness of the seismic isolation layer when the seismic isolation layer is controlled in a state close to the optimum. Therefore, when designing a semi-actively controlled seismic isolation layer, it is possible to explore the form of the layer rigidity of the seismic isolation layer when the seismic isolation layer is controlled in a state close to optimal, in order to use this as a design guideline.

[0009] In one aspect of the present invention, the search unit searches for the design variables by solving an optimization problem in which the displacement, the velocity, or the acceleration is an objective function, using the design variables as variables. According to the above-mentioned configuration, the design variables are searched for by solving an optimization problem with the displacement, velocity, or acceleration as an objective function, using the design variables as variables. Therefore, a solution close to the optimum can be derived for the design variables.

[0010] The present invention also provides a system for searching for seismic isolation layer characteristics, which searches for the characteristics of a seismic isolation layer for the purpose of reducing the amount of response when the seismic isolation layer of a seismic isolation structure is designed as semi-active control, and which is characterized in that the system includes a substructure and a superstructure of the seismic isolation structure below and above the seismic isolation layer, respectively, and the seismic isolation layer is modeled to actively update its characteristics, and the system includes a search unit that determines the characteristics of the seismic isolation layer by searching while updating the design variables so that the displacement, the velocity, or the acceleration is reduced in an equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure. According to the above-mentioned configuration, the seismic isolation layer is modeled so as to actively update its characteristics. In the seismic isolation layer that performs semi-active control, the design variables of the seismic isolation layer include the initial natural period of the seismic isolation layer, a plurality of time intervals at which the characteristics are updated, and an update value of the characteristics after a time equivalent to the time interval has elapsed, which is provided corresponding to each of the plurality of time intervals. When the initial natural period of the seismic isolation layer is determined, the initial values ​​of the specifications of the seismic isolation layer can be determined to determine the initial values ​​of the characteristics. After the first time interval of the plurality of time intervals has elapsed, new characteristics can be set and updated for the initial values ​​of the characteristics based on the update value after the time interval has elapsed. After that, after the next time interval has elapsed, new characteristics can be set and updated for the characteristics updated as described above based on the update value after the time interval has elapsed. In this way, the initial natural period of the seismic isolation layer, the plurality of time intervals, and the plurality of update values ​​are set as design variables, thereby defining the change in the characteristics over time. The search unit searches for the above-mentioned design variables while updating their values ​​so that the displacement, velocity, or acceleration, i.e., the response amount, is reduced in the equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure, and determines the characteristics of the seismic isolation layer. In this way, by searching for the design variable values ​​that reduce the response amount using the initial natural period of the seismic isolation layer, multiple time intervals, and multiple update values ​​as design variables, it is possible to search for the time and how the characteristics should be controlled to improve the response. Therefore, it becomes easier to find the form of the characteristics of the seismic isolation layer when it is controlled in a state close to the optimum. Therefore, when designing a semi-actively controlled seismic isolation layer, it is possible to explore the form of the characteristics of the seismic isolation layer when it is controlled in a state close to optimal, in order to use this as a design guideline.

[0011] In one aspect of the present invention, the characteristic is either a damping characteristic or an inertial mass, or a combination of two or more of the damping characteristic, the inertial mass, and the stiffness. According to the above-described configuration, when designing a semi-actively controlled seismic isolation layer, it is possible to explore either the form of the damping characteristics or the inertial mass of the seismic isolation layer, or a combination of two or more of the damping characteristics, inertial mass, and rigidity, when the seismic isolation layer is controlled in a state close to optimal, in order to use this as a design guideline.

[0012] The present invention also provides a seismic isolation structure designed using a seismic isolation layer characteristic exploration system, characterized in that it is equipped with a characteristic adjustment mechanism that adjusts the characteristics of the seismic isolation layer so as to realize the design variables determined using the seismic isolation layer characteristic exploration system as described above. According to the above-described configuration, the design variables determined using the above-described seismic isolation layer characteristic search system represent the form of the characteristics of the seismic isolation layer when the seismic isolation layer is controlled in a state close to the optimum. Therefore, by configuring a characteristic adjustment mechanism that adjusts the characteristics of the seismic isolation layer to realize these design variables, it is possible to realize a seismic isolation structure that can efficiently attenuate seismic forces. Effect of the Invention

[0013] According to the present invention, it is possible to provide a seismic isolation layer characteristic exploration system that is capable of exploring the characteristic form of a seismic isolation layer when the seismic isolation layer is controlled in a state close to optimal in order to use as a design guideline when designing a semi-actively controlled seismic isolation layer, and a seismic isolation structure designed using the seismic isolation layer characteristic exploration system. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a block diagram of a system for exploring seismic isolation layer characteristics in an embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of an example of a seismic isolation structure to be designed in the seismic isolation layer characteristic search system of the above embodiment. [Diagram 3] FIG. 11 is an explanatory diagram of another example of a seismic isolation structure to be designed in the seismic isolation layer characteristic exploration system of the above embodiment. [Figure 4]FIG. 2 is an explanatory diagram of an example of a model of a seismic isolation layer in the above embodiment. [Diagram 5] 5 is a graph showing an example of restoring force characteristics of a nonlinear spring in the model shown in FIG. 4. [Figure 6] 5 is a graph showing an example of a damping force characteristic of instantaneous stiffness proportional damping in the model shown in FIG. 4. [Figure 7] FIG. 11 is a diagram showing earthquake motion input in a verification example of the above embodiment. [Figure 8] FIG. 13 is a diagram showing the results of calculations in the above verification example. [Figure 9] FIG. 9 is a diagram showing the response acceleration, response displacement, restoring force, and natural period in the case of T=2.365 s among the results shown in FIG. 8, where the response is worse than when the stiffness is constant. [Figure 10] FIG. 9 is a diagram showing the response acceleration, response displacement, restoring force, and natural period when the stiffness is constant in the case of T=2.365 s among the results shown in FIG. 8. [Figure 11] FIG. 9 is a diagram showing the response acceleration, response displacement, restoring force, and natural period in the case of T=2.365 s among the results shown in FIG. 8, where the response is improved compared to the case where the stiffness is constant. [Figure 12] FIG. 12 is a graph showing the relationship between response displacement and restoring force for the results of FIG. 9 to FIG. 11 in which the response is worse than when the stiffness is constant, the results of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to a seismic isolation structure, a seismic isolation layer characteristic searching system for searching the characteristics of a seismic isolation layer in order to reduce the amount of response, and a seismic isolation structure designed using the seismic isolation layer characteristic searching system. The seismic isolation layer characteristic searching system is a method for searching for optimal seismic isolation layer characteristics by treating the seismic isolation layer characteristics as an optimization problem in order to reduce the amount of response of the seismic isolation layer, as an optimal design method for a seismic isolation structure. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a system for exploring seismic isolation layer characteristics in an embodiment of the present invention. The system 1 for searching for seismic isolation layer characteristics in this embodiment is a system for searching for the characteristics of a seismic isolation layer for the purpose of reducing the amount of response when the seismic isolation layer of a seismic isolation structure is designed as a semi-active control, the characteristic being stiffness, the substructure and superstructure of the seismic isolation structure are provided below and above the seismic isolation layer, respectively, the seismic isolation layer is modeled including a nonlinear spring that actively updates the tangent stiffness, and the initial natural period of the seismic isolation layer for determining the initial values ​​of the specifications of the seismic isolation layer, a plurality of time intervals at which the tangent stiffness is updated, and the updated value of the tangent stiffness after the time corresponding to each of the plurality of time intervals has elapsed are set as design variables, and the system 1 for searching for the stiffness of the seismic isolation layer while updating the design variables so that the displacement, velocity, or acceleration is reduced in the equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure. The system 1 for searching for seismic isolation layer characteristics is provided with a result output unit 3 in addition to the search unit 2.

[0016] The seismic isolation layer characteristic searching system 1 of this embodiment targets stiffness as a characteristic of the seismic isolation layer, and searches for the stiffness (story stiffness) of the seismic isolation layer with the aim of reducing the amount of response. The seismic isolation layer characteristic exploration system 1 of this embodiment targets a seismic isolation structure in which a seismic isolation layer is formed on a substructure, a superstructure is constructed on the seismic isolation layer, and the substructure and superstructure of the seismic isolation structure are provided below and above the seismic isolation layer, respectively, and is used to determine the rigidity of the seismic isolation layer of such a seismic isolation structure. In general, the vibration equation for a structure is given by m, c, the damping coefficient, k, the stiffness, a, the acceleration of the superstructure during an earthquake, v, the velocity, u, the displacement, and a g When the earthquake acceleration is m×a+c×v+k×u = m×a g The base isolation layer characteristic exploration system 1 of this embodiment explores the layer stiffness of the base isolation layer with the aim of reducing the amount of response when the base isolation layer of a base isolation structure is designed as semi-active control as described above. Here, semi-active control generally aims to suppress the response by changing any one of the mass m, damping coefficient c, or stiffness k in response to a disturbance, i.e., earthquake motion. In particular, the base isolation layer characteristic exploration system 1 of this embodiment actively controls and changes the stiffness of the base isolation layer to explore a stiffness change pattern that can efficiently respond to earthquake motion.

[0017] Items to be considered when designing and developing a seismic isolation layer based on semi-active control include the control mechanism ("what" to control) and the control law ("how" to control). As it is not possible to define in general terms the response value when the seismic isolation layer is optimally controlled, it is difficult to clearly set targets when designing the seismic isolation layer for these control mechanisms and control laws. Therefore, the performance evaluation of a designed seismic isolation layer must be done in a relative manner, in terms of how much it has improved over existing control methods. In contrast, as described above, when designing and developing a seismic isolation layer based on semi-active control, the seismic isolation layer characteristic exploration system 1 of this embodiment can be used to derive the layer stiffness of the seismic isolation layer that will respond close to the optimal state, making it possible to confirm the validity of the development policy set when designing the seismic isolation layer, and how close the devised control law is to the target, and the degree of achievement.

[0018] Furthermore, the search system 1 for seismic isolation layer characteristics of this embodiment is particularly targeted at the design of seismic isolation layers for feedforward semi-active control that performs control based on disturbance information several seconds ahead, and derives the optimal response that is the target value of the feedforward control and the control state at that time by using an optimization method using a genetic algorithm, etc. Specifically, it is assumed that the disturbance is known, and after setting the design variables to be varied in the semi-active control, the values ​​of the design variables that optimize the response that is the objective function are derived by solving an optimization problem.

[0019] When the seismic isolation layer characteristic search system 1 as described above has searched for the layer stiffness of the seismic isolation layer that optimizes the response, a seismic isolation structure equipped with a seismic isolation layer that performs feedforward semi-active control to achieve this can be configured as follows, for example. FIG. 2 is an explanatory diagram of an example of a seismic isolation structure to be designed in the search system for seismic isolation layer characteristics of this embodiment. The seismic isolation structure 10 comprises a substructure 11, a superstructure 12, and a seismic isolation layer 13 provided between the substructure 11 and the superstructure 12. The seismic isolation layer 13 comprises a plurality of laminated rubber bearings 14, and is structured so that the superstructure 12 can move horizontally relative to the substructure 11 during an earthquake.

[0020] The seismic isolation structure 10 further includes a sensor 16, a control device 17, and a characteristic adjustment mechanism 15. The sensor 16 is, for example, an accelerometer, and measures the acceleration acting on the superstructure 12 during an earthquake. The control device 17 includes a prediction unit 18 and a control unit 19. The prediction unit 18 predicts the acceleration acting on the superstructure 12 several seconds into the future based on the measurement results from the sensor 16. The control unit 19 controls the characteristic adjustment mechanism 15, which will be described next, based on the future acceleration predicted by the prediction unit 18. The control unit 19 is designed in such a way that how to control the characteristic adjustment mechanism 15 is achieved, with the goal of realizing the design variables determined by the seismic isolation layer characteristic exploration system 1.

[0021] The characteristic adjustment mechanism 15 adjusts the characteristics of the seismic isolation layer 13. The characteristic adjustment mechanism 15 imparts rigidity to the seismic isolation layer 13. The characteristic adjustment mechanism 15 adjusts the rigidity of the seismic isolation layer 13 as needed, at the timing instructed by the control unit 19, so that the rigidity of the seismic isolation layer 13 becomes the value instructed by the control unit 19. Examples of such characteristic adjustment mechanism 15 include a sliding bearing or a friction damper that can switch the friction coefficient and therefore the damping force by controlling the smoothness of the sliding surface. A sliding bearing or a friction damper that can switch the damping force by changing the electromagnetic force to switch the introduced axial force may also be used as the characteristic adjustment mechanism 15. Alternatively, an oil damper that can switch the damping force by controlling the opening and closing of a valve may also be used as the characteristic adjustment mechanism 15.

[0022] FIG. 3 is an explanatory diagram of another example of a seismic isolation structure to be designed in the search system for seismic isolation layer characteristics of this embodiment. The seismic isolation structure 10A shown in Fig. 3 includes a lower structure 11, an upper structure 12, and an intermediate structure 20 constructed between them. Accordingly, the seismic isolation layer 13 includes two seismic isolation layers, a lower seismic isolation layer 13A and an intermediate seismic isolation layer 13B. The intermediate seismic isolation layer 13B is provided with an elastic sliding support body 21. The lower seismic isolation layer 13A is set to have a horizontal rigidity smaller than that of the intermediate seismic isolation layer 13B. The characteristic adjustment mechanism 15 increases the horizontal rigidity of the lower seismic isolation layer 13A. The characteristic adjustment mechanism 15 increases the horizontal rigidity of the lower seismic isolation layer 13A in accordance with the amount of deformation of the lower seismic isolation layer 13A caused by the horizontal displacement of the intermediate structure 20 relative to the substructure 11 due to seismic motion. The characteristic adjustment mechanism 15 is a stopper for limiting the deformation of the lower seismic isolation layer 13A. In such a configuration, at normal design earthquake motion levels, deformation occurs only in the lower seismic isolation layer 13A, which has a small horizontal stiffness, and seismic isolation performance is demonstrated. At this time, deformation is suppressed in the intermediate seismic isolation layer 13B, which has a larger horizontal stiffness than the lower seismic isolation layer 13A. At an excessive earthquake motion level exceeding the normal design level, the intermediate structure 20 collides with the characteristic adjustment mechanism 15 (stopper), increasing the horizontal rigidity of the lower seismic isolation layer 13A and limiting the seismic isolation effect exerted by the lower seismic isolation layer 13A. Then, the shear force due to the external force (earthquake load) caused by the earthquake motion is transmitted to the upper layer than the lower seismic isolation layer 13A, and the elastic sliding support 21 causes a slip in the intermediate seismic isolation layer 13B. This causes a horizontal relative displacement between the intermediate structures 20 and the upper structure 12 above and below the intermediate seismic isolation layer 13B, causing deformation in the intermediate seismic isolation layer 13B. This allows the intermediate seismic isolation layer 13B to exert its seismic isolation performance. In such a configuration, for example, a stopper can be provided so as to be able to move forward and backward from the retaining wall on which the stopper is provided, and the distance between the tip of the stopper and the intermediate structure 20 can be adjusted, and the distance can be adjusted and controlled by the control unit 19, so that the stopper can be used as a characteristic adjustment mechanism 15.

[0023] As described above, the system 1 for searching seismic isolation layer characteristics sets the design variables to be varied in the semi-active control, and then derives the values ​​of the design variables that optimize the response that is the objective function by solving an optimization problem. In this optimization problem, the design variables are variables that represent the control status during the response. The objective function is to minimize the response amount. The response amount may be any one of the displacement, velocity, and acceleration of the upper structure 12, or a combination of two or more of them. In this embodiment, the response amount is the displacement and acceleration. Also, the constraint for solving the optimization problem is that the limit of the control mechanism is not exceeded.

[0024] In the seismic isolation layer characteristic exploration system 1, initial values ​​are first set for the mass of the superstructure that constitutes the seismic isolation structure, the initial natural period of the seismic isolation layer 13, the tangent stiffness of the seismic isolation layer 13, the modeling of the nonlinear spring that updates the tangent stiffness, the damping coefficient of the seismic isolation layer 13, etc. Thereafter, the search unit 2 searches for the stiffness of the seismic isolation layer (story stiffness). FIG. 4 is an explanatory diagram of an example of a model of a seismic isolation layer in this embodiment. Here, the behavior of the search unit 2 will be described using a one-mass point shear model M as shown in FIG. 4 as an example. In the one-mass point shear model M, the mass of the upper structure 12 is set to, for example, 8000 (T). In the one-mass point shear model M, the seismic isolation layer 13 is set to a stiffness term f k (t) as the nonlinear spring 30 and the damping term f c It has an instantaneous stiffness proportional damping 31 as (t). As mentioned above, the stiffness term f k (t) is the nonlinear spring 30. The nonlinear spring 30 actively updates the tangent stiffness. As will be described later in detail, the design variables of the optimization problem in this embodiment include the initial natural period of the seismic isolation layer 13 for determining the initial value of the tangent stiffness. The design variables also include a plurality of combinations of time intervals and updated values ​​of the tangent stiffness. As a result, the value of the tangent stiffness is defined such that each of the plurality of combinations is applied in order to the initial value of the tangent stiffness determined by the initial natural period of the seismic isolation layer 13, and the tangent stiffness is updated based on the updated value in the combination after the time interval in the combination has elapsed from the time when the tangent stiffness was last calculated. In other words, the behavior of the nonlinear spring 30 is determined according to the time and the state of the nonlinear spring 30 at that time. In this embodiment, while defining the behavior of the nonlinear spring 30 as described above, a thorough search is performed by the optimization problem to determine at what time and how the stiffness should be controlled to improve the response. In this example, the nonlinear spring 30 is a nonlinear elastic spring. The nonlinear spring 30 may not be a nonlinear elastic spring, but may be, for example, an oil damper capable of switching the damping force as exemplified above, and the following description can be applied in the same manner. Also, as mentioned above, the damping term f c (t) is the instantaneous stiffness proportional damping 31, which is proportional to the tangent stiffness at each instant.

[0025] Fig. 5 is a graph showing an example of restoring force characteristics of a nonlinear spring in the model shown in Fig. 4. Fig. 6 is a graph showing an example of damping force characteristics of instantaneous stiffness proportional damping in the model shown in Fig. 4. In Fig. 5 and Fig. 6, numbers 1 to 12 show examples of how stiffness and damping change. These numbers are used correspondingly in Fig. 5 and Fig. 6. The circles in Fig. 5 indicate points where stiffness has been changed. For example, in Fig. 5, after the displacement increases as indicated by arrow 1, the stiffness is changed, the relationship between the displacement and the restoring force changes, and it transitions to arrow 2. At this point in time, the relationship between the velocity and the damping force changes, as indicated by the arrow from number 1 to number 2 in Fig. 6.

[0026] The restoring force characteristics of this example (Fig. 5) are such that stiffness changes occur only when the load is not being removed, and the tangent stiffness changes from that point on. Also, since an area caused by a hysteresis loop causes energy absorption and reduces the response, when unloading, the path that was traced from the origin to the most recent maximum response point is always returned, and an active nonlinear elasticity type is used that does not cause energy absorption due to a hysteresis loop regardless of the behavior. Furthermore, the damping force characteristics of this example (Fig. 6) are of the instantaneous stiffness proportional damping type, where the damping coefficient is also changed so that the damping constant is always kept constant in response to the change in tangential stiffness as described above. More specifically, the damping constant h is calculated using the damping coefficient c, mass m, and stiffness k as h=c / (2×(mk)^(1 / 2)), but when m is constant, the damping coefficient c is changed so that the damping constant h remains constant when the stiffness k changes. The damping coefficient is of the proportional type, always expressed as a proportional coefficient connecting the origin and the response point. Each characteristic shown in FIG. 5 and FIG. 6 may not necessarily be the best setting when considering the performance and feasibility of AI control. Here, in this embodiment, the purpose is not to reduce the response by applying damping, but to consider semi-active control that reduces the response, and it is desirable to adopt a form in which the amount of damping, i.e., the damping constant, is not changed as much as possible. In this regard, when the restoring force characteristic and the damping force characteristic are set as described above, the damping constant h becomes constant, and the control in the semi-active control does not directly affect the magnitude of damping. In this sense, each characteristic shown in FIG. 5 and FIG. 6 is a model that is easy to evaluate from the viewpoint of comparison with the response spectrum, etc.

[0027] The equation of motion for each characteristic shown in FIG. 5 and FIG. 6 is expressed as the following equation (1).

number

number

number

number

[0028] Next, in this embodiment, the problem to be solved is defined. This problem is "how to determine the tangent stiffness k t How can we control the response to minimize the response? To formulate this problem as an optimization problem, we consider the design variables and the tangent stiffness k t The update rules are established to update the First, the design variables include the initial natural period T0 of the seismic isolation layer 13. By substituting the initial natural period T0 of the seismic isolation layer 13 into the following equation (5), the initial values ​​of the specifications of the seismic isolation layer, more specifically, the initial value k t0 can be determined.

number

[0029] It has been explained that the value of the tangent stiffness is defined by sequentially applying each of a plurality of combinations of time intervals and updated values ​​of the tangent stiffness to the initial value of the tangent stiffness determined by the initial natural period of the seismic isolation layer 13, and updating the tangent stiffness based on the updated value in the combination after the time interval in the combination has elapsed from the time when the tangent stiffness was last calculated. Among these, the initial value of the tangent stiffness is determined by the above formula (5). After the time history response analysis is started, a plurality of combinations of time intervals and updated values ​​of the tangent stiffness are appropriately applied to this initial value of the tangent stiffness, and the change in the tangent stiffness is expressed by the design variables so that the tangent stiffness is updated as time progresses in the time history response analysis. In this way, the tangent stiffness is updated as time progresses in the time history response analysis. A tangent stiffness update step i (i = 1 to n, n is the number of components) is defined as a variable that represents each stage at which the tangent stiffness is updated, i.e., how many times the tangent stiffness has been updated. When the tangent stiffness is at its initial value, it is considered that the tangent stiffness has been updated once by setting the initial value, and the state is tangent stiffness update step i = 1. After time has passed and the tangent stiffness has been updated once from the initial value, the state is considered to be tangent stiffness update step i = 2.

[0030] The design variables are updated at multiple time step intervals where the tangent stiffness is updated. trans dt i where i is the tangent stiffness update step i (i = 1 to n). Time step interval trans dt i Each of these is considered in this embodiment to be a continuous variable, ie, may take any value, for example, between 1.0s and 2.0s. The design variables include an updated value of the tangent stiffness after a time corresponding to each of the multiple time intervals has elapsed. Strictly speaking, in this embodiment, the coefficient α is determined by selecting one of the values ​​0.5, 1, and 2.0. i (i=1~n) is the design variable that corresponds to the updated value. The tangent stiffness k in the previous tangent stiffness update step i-1 t(i-1) For coefficient α i By multiplying as in the following equation (6), the tangent stiffness k ti is uniquely determined as the update value.

number

[0031] In this way, for the tangent stiffness update step i, the time step interval is trans dt i and the update coefficient (update value) α i Using this, in the tangent stiffness update step i, the time interval from the start of the tangent stiffness update step i is trans dt i After the time corresponding to the update coefficient (update value) α i The tangent stiffness is modified and updated based on In this way, in the seismic isolation layer characteristic searching system 1 of this embodiment, the initial value k of the tangent stiffness t0 The initial natural period T0 and tangent stiffness k of the seismic isolation layer 13 are determined. ti The number of time intervals at which trans dt i , and multiple time step intervals trans dt i The time intervals are set corresponding to each of the trans dt i The updated value of the tangent stiffness after a time corresponding to i ) are the design variables.

[0032] Based on such design variables, the tangent stiffness is updated as time progresses after the start of the time history response analysis, based on the following rules 1 to 3, where: trans t i Let be the time when the tangent stiffness is updated for the i-th time. Specifically, the time when the tangent stiffness update step i transitions to the tangent stiffness update step i+1 is transt i It becomes. Rule 1: At time t = 0, the tangent stiffness update step i = 1. trans Let t0=0. Rule 2: t≧ trans t i-1 + trans dt i , and when the load is not being removed, the tangent stiffness k ti Also, update the time trans t i In addition, add 1 to the tangent stiffness update step i. Rule 3: After that, rule 2 is repeated until the time history response analysis is completed.

[0033] According to the above rules 1 to 3, the tangent stiffness k ti The following is an example of how to calculate (Step 1) According to rule 1, time t=0, tangential stiffness update step i=1, tangential stiffness update time trans t0 = 0. In addition, from the initial natural period T0 of the seismic isolation layer 13, the initial value k of the tangent stiffness is calculated according to the above formula (5). t0 Calculate.

[0034] (Step 2) In the time history response analysis, the time t is increased slightly. Time t = trans t0+ trans The time when the tangent stiffness was last updated is dt1. trans Time interval from t0 trans If the load is not removed at the time dt1 has elapsed, the displacement u at that time t corresponds to the first circle in the restoring force characteristics in FIG. 5. Tangent stiffness update time trans Time interval from t0 trans If the load is removed when dt1 has elapsed, the displacement u at the time when the load is no longer removed after time t will be the part corresponding to the first circle in the restoring force characteristics of Figure 5. At such a moment, the tangent stiffness k t1 =α1×k t0 Then, update the tangent stiffness as follows. transSet t1. Update the tangent stiffness update step to i=2. In this step 2, trans The time set as t1 is the time t= trans t0+ trans If the load is removed when dt1 is reached, the time t continues to increase until the load is removed and the load is removed, and the tangent stiffness and the tangent stiffness update step i are not updated and are maintained during this time. Therefore, trans t1 is trans t0+ trans It is not always equal to the value of dt1. Also, the update coefficient α1 may be set to a value of “1”. In this case, even if the tangent stiffness update step i is updated to 2, the tangent stiffness k t1 is the tangent stiffness k in the previous tangent stiffness update step i (i=1) t0 Therefore, when the update coefficient α1=1, for example, at the stiffness change point of the restoring force characteristic shown in FIG. 5, the relationship between the displacement and the restoring force does not change, and a circle is provided on the straight line. On the other hand, when the update coefficient α1 is not 1, the relationship between the displacement and the restoring force changes, and a circle is provided at the part where straight lines with different slopes connect.

[0035] (Step 3) Time t is further increased slightly. Consider the state where loading ends, unloading begins, and the displacement decreases. In the unloading state, for example, in the restoring force characteristics shown in Figure 5, the path traveled from the origin to the most recent maximum response point is retraced. It reaches the same circle as in step 2, and then at a certain time it starts loading. During this time, time t = trans t1+ trans If dt2 has passed, the moment loading begins, the tangent stiffness k is calculated based on equation (6). t2 =α2×k t1 As the tangent stiffness k t2 Update this moment. trans t2= trans t1+ trans dt2. Update the tangent stiffness update step to i=3. (Step 4 and onwards) Repeat the operations equivalent to steps 2 and 3 in the same manner. In step 2, if "0", "1", and "2" are read as "i-1", "i", and "i+1", respectively, it will become a more general expression. Similarly, in step 2, if "1", "2", and "3" are read as "i-1", "i", and "i+1", respectively, it will become a more general expression.

[0036] By repeating the above steps based on rules 1 to 3, the restoring force characteristics as shown in Figure 5 are obtained. In other words, the characteristics in Figure 5 are not predetermined, but are obtained as a result of the response. It has been explained that the restoring force characteristics in Figure 5 are of an active nonlinear elastic type, which means that the restoring force characteristics are actively changed by the structure itself according to the seismic motion and vibration state.

[0037] In this way, the initial value of the tangent stiffness k t0 The initial natural period T0 and tangent stiffness k of the seismic isolation layer 13 are determined. ti The number of time intervals at which trans dt i , and multiple time step intervals trans dt i The time intervals are set corresponding to each of the trans dt i The updated value of the tangent stiffness after a time corresponding to i ) are used as design variables, and by setting certain values ​​for each of these design variables, it is possible to realize one restoring force characteristic. The search unit 2 of the search system 1 for seismic isolation layer characteristics searches for values ​​that should be set for these design variables in order to realize an appropriate rigidity of the seismic isolation layer. In this embodiment, the search unit 2 searches for design variables by solving an optimization problem in which the design variables are variables and the displacement, velocity, or acceleration is an objective function. In the following, a case will be described in which this search is performed using a genetic algorithm, which is a multi-objective optimization algorithm, as the optimization method, although it goes without saying that optimization methods other than the genetic algorithm may also be used.

[0038] Specifically, the search unit 2 first generates one stiffness setting candidate plan by, for example, randomly setting the values ​​of each design variable. The search unit 2 generates a plurality of stiffness setting candidates different from each other by setting different design variables, and these are regarded as first-generation stiffness setting candidates. Next, the search unit 2 evaluates each of the first generation stiffness setting candidate plans. Specifically, the search unit 2 actually solves the equation of motion for each of the stiffness setting candidate plans, performs a time history response analysis, and calculates the maximum response amounts of displacement, velocity, and acceleration. The search unit 2 executes a selection operation in a genetic algorithm for the multiple stiffness setting candidates thus evaluated. Based on the evaluation results of each stiffness setting candidate, the search unit 2 selects multiple stiffness setting candidates that have obtained good evaluation results from among the multiple stiffness setting candidates, and excludes and deletes the remaining stiffness setting candidates that have not been selected from the candidates to be finally adopted.

[0039] Next, the search unit 2 executes each of the crossover and mutation operations in the genetic algorithm to generate new stiffness setting candidates based on the multiple stiffness setting candidates selected by the selection operation. As already described, the multiple stiffness setting candidates previously evaluated were generated by setting values ​​for each of the design variables. In the crossover operation, the search unit 2 arbitrarily selects two stiffness setting candidates from the multiple stiffness setting candidates selected by the selection operation, and exchanges some of the values ​​set for each of the multiple design variables that were used as the basis for generating these two stiffness setting candidates with each other, thereby generating two new stiffness setting candidates by setting the design variable settings to different values. In addition, in the mutation operation, the search unit 2 generates a new stiffness setting candidate for any stiffness setting candidate among the multiple stiffness setting candidate plans by randomly changing a part of the values ​​set for each of the multiple design variables that were used as the basis for generating the stiffness setting candidate plan to other values. In this manner, the search unit 2 selects multiple stiffness setting candidate plans from the previously evaluated stiffness setting candidate plans by the selection operation of the genetic algorithm, and generates multiple new stiffness setting candidate plans by setting new values ​​for each of the multiple design variables based on the values ​​from which the selected multiple stiffness setting candidate plans were generated by each of the crossover and mutation operations of the genetic algorithm. The new generation of multiple stiffness setting candidate proposals generated in this manner is likely to be evaluated by the search unit 2 in a more favorable manner overall than the previous generation of multiple stiffness setting candidate proposals from which the new stiffness setting candidate proposals were generated.

[0040] Such evaluation of multiple stiffness setting candidates and generation (updating) of new stiffness setting candidates are repeated multiple times (multiple generations) to generate multiple final stiffness setting candidates. In this way, the search unit 2 determines the rigidity of the seismic isolation layer by searching and updating the design variables so as to reduce the displacement, velocity, or acceleration in the equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure. When the above-mentioned repetition of evaluation of a plurality of stiffness setting candidates and generation (update) of new stiffness setting candidates is completed, the result output unit 3 outputs the results.

[0041] In this way, a characteristic adjustment mechanism 15 is constructed to adjust the rigidity of the seismic isolation layer 13 so as to realize the design variables determined using the seismic isolation layer characteristic exploration system 1, and by providing the characteristic adjustment mechanism 15 in the seismic isolation layer 13, a seismic isolation structure 10 can be constructed that can efficiently attenuate seismic forces.

[0042] The seismic isolation layer characteristic search system 1 described above is a seismic isolation layer characteristic search system 1 that searches for the characteristics of the seismic isolation layer 13 of a seismic isolation structure 10 with the aim of reducing the response amount when the seismic isolation layer 13 is designed as a semi-active control, the characteristic being rigidity, and the substructure 11 and superstructure 12 of the seismic isolation structure 10 are provided below and above the seismic isolation layer 13, respectively. The seismic isolation layer 13 is modeled to include a nonlinear spring that actively updates the tangent rigidity, and is equipped with a search unit 2 that determines the rigidity of the seismic isolation layer by searching while updating the design variables so that the displacement, velocity, or acceleration is reduced in an equation of motion expressed by the displacement, velocity, and acceleration of the superstructure 12 relative to the substructure 11. According to the above-mentioned configuration, the seismic isolation layer 13 is modeled including a nonlinear spring that actively updates the tangent stiffness. With respect to such a seismic isolation layer 13 that performs semi-active control, the design variables of the seismic isolation layer 13 include the initial natural period of the seismic isolation layer 13, a plurality of time intervals at which the tangent stiffness is updated, and an updated value of the tangent stiffness after a time equivalent to the time interval has elapsed, which is provided corresponding to each of the plurality of time intervals. Once the initial natural period of the seismic isolation layer 13 is determined, the initial value of the tangent stiffness can be determined by determining the initial values ​​of the seismic isolation layer. After the first time interval among the plurality of time intervals has elapsed, a new tangent stiffness can be set and updated for the initial value of the tangent stiffness based on the updated value after the time interval has elapsed. After that, after the next time interval has elapsed, a new tangent stiffness can be set and updated for the tangent stiffness updated as described above based on the updated value after the time interval has elapsed. In this way, the initial natural period of the seismic isolation layer 13, multiple time intervals, and multiple update values ​​are used as design variables to define the change in tangential stiffness over time. The search unit 2 searches for the above-mentioned design variables while updating their values ​​so that the displacement, velocity, or acceleration, i.e., the response amount, is reduced in the equation of motion expressed by the displacement, velocity, and acceleration of the upper structure 12 relative to the lower structure 11, and determines the stiffness of the seismic isolation layer. In this way, the initial natural period of the seismic isolation layer 13, multiple time intervals, and multiple update values ​​are used as design variables to search for values ​​of the design variables that reduce the response amount, thereby searching for what time and how to control the stiffness to improve the response. Therefore, it becomes easier to find the form of the layer stiffness of the seismic isolation layer 13 when the seismic isolation layer 13 is controlled in a state close to the optimum. Therefore, when designing a semi-actively controlled seismic isolation layer 13, it is possible to explore the form of layer rigidity of the seismic isolation layer 13 when the seismic isolation layer 13 is controlled in a state close to optimal, in order to use this as a design guideline.

[0043] Moreover, the search unit 2 searches for design variables by solving an optimization problem in which the displacement, the velocity, or the acceleration is an objective function, using the design variables as variables. According to the above-mentioned configuration, the design variables are searched for by solving an optimization problem with the displacement, velocity, or acceleration as an objective function, using the design variables as variables. Therefore, a solution close to the optimum can be derived for the design variables.

[0044] The seismic isolation structure 10 also includes a characteristic adjustment mechanism 15 that adjusts the characteristics of the seismic isolation layer 13 so as to realize the design variables determined using the seismic isolation layer characteristic search system 1 described above. According to the above-described configuration, the design variables determined using the above-described seismic isolation layer characteristic search system 1 represent the form of the characteristics of the seismic isolation layer 13 when the seismic isolation layer 13 is controlled in a state close to the optimum. Therefore, by configuring a characteristic adjustment mechanism 15 that adjusts the characteristics of the seismic isolation layer 13 to realize these design variables, it is possible to realize a seismic isolation structure 10 that can efficiently attenuate seismic forces.

[0045] (Verification example) Verification was carried out on the above-mentioned system 1 for searching seismic isolation layer characteristics, and the results will be described below. FIG. 7 is a diagram showing earthquake motions input in a verification example. The input earthquake motion was BCJ-L2 (PGA = 344 cm / s 2 ) was used. Since the earthquake motion duration was 120 seconds, the design variable ( trans dt i , α i ) The number of components is n = 120 × 0.8 = 96, so it was set to 100. For optimization, we used the composite strategy algorithm "pilOPT" implemented in ESTECO's optimization preprocessor modeFRONTIER. The number of calculations was 20,000, and the Newmark-β method (β=1 / 4) was used for time history response analysis. Displacement and acceleration were used as objective functions for optimization.

[0046] FIG. 8 shows the optimization calculation results. In FIG. 8, the results are plotted with the lower limit of T set to 0.0 and the upper limit set to 4.0. Among these, the results are plotted so that the results with T values ​​closer to the lower limit are mainly distributed to the left in FIG. 8, where the maximum response displacement is small, and the results with T values ​​closer to the upper limit are mainly distributed to the right in FIG. 8, where the maximum response displacement is large. In FIG. 8, the constant stiffness Sa-Sd spectrum is shown as line L1. In FIG. 8, several designs are seen that are improved over this constant stiffness Sa-Sd spectrum. Among them, the "T=2.365s improved solution" is shown with the symbol P1. Furthermore, the response point when the stiffness is constant with the same initial stiffness is shown on the constant stiffness Sa-Sd spectrum with the reference P2, and the design with the same initial stiffness but with a worsened response is shown with the reference P3.

[0047] FIG. 9 is a diagram showing the response acceleration, response displacement, restoring force, and natural period of the result of the response being worsened compared to the case where the stiffness is constant in the case of T=2.365 s in the results shown in FIG. 8. FIG. 10 is a diagram showing the response acceleration, response displacement, restoring force, and natural period of the result of the response being made constant in the case of T=2.365 s in the results shown in FIG. 8. FIG. 11 is a diagram showing the response acceleration, response displacement, restoring force, and natural period of the result of the response being improved compared to the case where the stiffness is constant in the case of T=2.365 s in the results shown in FIG. 8. FIG. 12 is a graph showing the relationship between the response displacement and the restoring force of the result of the response being worsened compared to the case where the stiffness is constant, the result of the stiffness being constant, and the result of the response being improved compared to the case where the stiffness is constant in FIGS. 9 to 11. As shown in Fig. 9, in the deteriorated solution, a large acceleration occurs when the stiffness is increased for a certain period of time up to around T = 1.0 s. On the other hand, as shown in Fig. 11, in the improved solution, the maximum response value is suppressed by locally increasing the stiffness as shown as P5 a little before the maximum response observed as shown as P4.

[0048] Furthermore, the seismic isolation layer characteristic exploration system of the present invention and the seismic isolation structure designed using the seismic isolation layer characteristic exploration system are not limited to the above-mentioned embodiment described with reference to the drawings, and various other modified examples are possible within the technical scope.

[0049] For example, the seismic isolation layer characteristic searching system has set the characteristic to be searched for as stiffness, but this is not limited thereto. Needless to say, the characteristic to be searched for by the seismic isolation layer characteristic searching system may be, for example, damping characteristic. Alternatively, the property to be searched for by the seismic isolation layer property search system may be inertial mass. Inertial mass is the property of an object that exhibits a repulsive force against a physical force, and is expressed by the change in the momentum of the object. The greater the inertial mass of an object, the greater the repulsive force against that force. This is also true when the mass of the object is large. Inertial mass is not affected by the size or shape of the object, and is treated as a quantity separate from mass. Furthermore, the characteristics to be searched for by the system for searching for seismic isolation layer characteristics may be a combination of two or more of the damping characteristics, the inertial mass, and the stiffness.

[0050] In other words, the above-mentioned system for searching for seismic isolation layer characteristics is a system for searching for seismic isolation layer characteristics with the aim of reducing the response amount when the seismic isolation layer of a seismic isolation structure is designed as semi-active control, and the system is characterized in that the substructure and superstructure of the seismic isolation structure are provided below and above the seismic isolation layer, respectively, and the seismic isolation layer is modeled to actively update its characteristics, and the initial natural period of the seismic isolation layer for determining the initial values ​​of the specifications of the seismic isolation layer, a plurality of time intervals at which the characteristics are updated, and the updated values ​​of the characteristics after the elapse of a time equivalent to each of the plurality of time intervals, which are provided corresponding to each of the plurality of time intervals, are used as design variables, and the system provides a search unit that determines the characteristics of the seismic isolation layer by searching while updating the design variables so that the displacement, velocity, or acceleration is reduced in an equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure. According to the above-mentioned configuration, the seismic isolation layer is modeled so as to actively update its characteristics. In the seismic isolation layer that performs semi-active control, the design variables of the seismic isolation layer include the initial natural period of the seismic isolation layer, a plurality of time intervals at which the characteristics are updated, and an update value of the characteristics after a time equivalent to the time interval has elapsed, which is provided corresponding to each of the plurality of time intervals. When the initial natural period of the seismic isolation layer is determined, the initial values ​​of the specifications of the seismic isolation layer can be determined to determine the initial values ​​of the characteristics. After the first time interval of the plurality of time intervals has elapsed, new characteristics can be set and updated for the initial values ​​of the characteristics based on the update value after the time interval has elapsed. After that, after the next time interval has elapsed, new characteristics can be set and updated for the characteristics updated as described above based on the update value after the time interval has elapsed. In this way, the initial natural period of the seismic isolation layer, the plurality of time intervals, and the plurality of update values ​​are set as design variables, thereby defining the change in the characteristics over time. The search unit searches for the above-mentioned design variables while updating their values ​​so that the displacement, velocity, or acceleration, i.e., the response amount, is reduced in the equation of motion expressed by the displacement, velocity, and acceleration of the superstructure relative to the substructure, and determines the characteristics of the seismic isolation layer. In this way, by searching for the design variable values ​​that reduce the response amount using the initial natural period of the seismic isolation layer, multiple time intervals, and multiple update values ​​as design variables, it is possible to search for the time and how the characteristics should be controlled to improve the response. Therefore, it becomes easier to find the form of the characteristics of the seismic isolation layer when it is controlled in a state close to the optimum. Therefore, when designing a semi-actively controlled seismic isolation layer, it is possible to explore the form of the characteristics of the seismic isolation layer when it is controlled in a state close to optimal, in order to use this as a design guideline.

[0051] In such configurations, the characteristic may be, among others, either damping characteristics or inertial mass, or a combination of two or more of damping characteristics, inertial mass, and stiffness. According to the above-described configuration, when designing a semi-actively controlled seismic isolation layer, it is possible to explore either the form of the damping characteristics or the inertial mass of the seismic isolation layer, or a combination of two or more of the damping characteristics, inertial mass, and rigidity, when the seismic isolation layer is controlled in a state close to optimal, in order to use this as a design guideline.

[0052] In addition, it is possible to select and discard the configurations given in the above embodiment and modified examples, or to change them to other configurations as appropriate. [Explanation of symbols]

[0053] 1 Seismic isolation layer characteristic detection system 13 Seismic isolation layer 2 Search section 15 Characteristic adjustment mechanism 10 Seismic isolation structure 30 Nonlinear spring 11 Substructure 31 Instantaneous stiffness proportional damping 12 Superstructure

Claims

1. A system for searching characteristics of a seismic isolation layer for searching characteristics of the seismic isolation layer for the purpose of reducing a response amount when the seismic isolation layer of a seismic isolation structure is designed as a semi-active control, comprising: The property is stiffness, A substructure and a superstructure of the seismic isolation structure are provided below and above the seismic isolation layer, respectively, and the seismic isolation layer is modeled including a nonlinear spring that actively updates the tangent stiffness; The initial natural period of the seismic isolation layer for determining the initial values ​​of the specifications of the seismic isolation layer, a plurality of time intervals at which the tangent stiffness is updated, and an updated value of the tangent stiffness after a time equivalent to each of the plurality of time intervals has elapsed, which is set corresponding to each of the plurality of time intervals, are set as design variables, A search unit is provided for determining the stiffness of the seismic isolation layer by searching while updating the design variables so that the displacement, the velocity, or the acceleration is reduced in an equation of motion expressed by the displacement, the velocity, and the acceleration of the upper structure relative to the lower structure. A system for searching for seismic isolation layer characteristics.

2. The search unit searches for the design variables by solving an optimization problem in which the displacement, the velocity, or the acceleration is an objective function, using the design variables as variables. The system for searching for seismic isolation layer characteristics according to claim 1 .

3. A system for searching characteristics of a seismic isolation layer for searching characteristics of the seismic isolation layer for the purpose of reducing a response amount when the seismic isolation layer of a seismic isolation structure is designed as a semi-active control, comprising: A substructure and a superstructure of the seismic isolation structure are provided below and above the seismic isolation layer, respectively, and the seismic isolation layer is modeled to actively update the characteristics; The initial natural period of the seismic isolation layer for determining the initial values ​​of the specifications of the seismic isolation layer, a plurality of time intervals at which the characteristics are updated, and updated values ​​of the characteristics after a time equivalent to each of the time intervals has elapsed, the updated values ​​being set corresponding to each of the plurality of time intervals; A search unit is provided for determining the characteristics of the seismic isolation layer by searching while updating the design variables so that the displacement, the velocity, or the acceleration is reduced in an equation of motion expressed by the displacement, the velocity, and the acceleration of the upper structure relative to the lower structure. A system for searching for seismic isolation layer characteristics.

4. The system for searching for seismic isolation layer characteristics according to claim 3, wherein the characteristic is either a damping characteristic or an inertial mass, or a combination of two or more of the damping characteristic, the inertial mass, and the stiffness.

5. A seismic isolation structure designed using a seismic isolation layer characteristic exploration system, characterized in that it is provided with a characteristic adjustment mechanism that adjusts the characteristics of the seismic isolation layer so as to realize the design variables determined using the seismic isolation layer characteristic exploration system described in any one of claims 1 to 4.

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