Semi-active Isolation System Research Articles

MR流体ダンパを用いたセミアクティブ免震構造 ―第1報, MR流体ダンパの特性実験―

MR流体ダンパを用いたセミアクティブ免震構造 ―第1報, MR流体ダンパの特性実験―

Optimal Control: Basis for Performance Comparison of Passive and Semiactive Isolation Systems

Passive damping in shock and vibration isolation systems reduces the deformation of the isolation system but can increase the acceleration sustained by the isolated object. Semiactive (i.e., controllable) damping systems offer a solution to the problem of increased vibration transmissibility at high frequencies. Semiactive damping is especially relevant to protecting acceleration-sensitive components to the effects of large impulsive earthquakes. In this paper, we compare three semiactive control policies, i.e., pseudonegative-stiffness control, continuous pseudoskyhook-damping control, and bang-bang pseudoskyhook-damping control, in terms of their effectiveness in addressing the deficiencies of passive isolation damping. In order to establish a performance goal for these suboptimal semiactive control rules, we present a method for true optimization of the response of dynamically excited, semiactively controlled structures subjected to constraints imposed by the dynamics of a particular semiactive device....

432 可変減衰ダンパを用いたセミアクティブ免震構造に関する研究

This paper describes isolation performance of semi-active seismic isolation system using variable damper. Recently, the relatively long period seismic waves have been observed in the various earthquakes. These seismic waves have the predominant period that is equivalent to natural period of seismic isolation structures. Therefore technology is required that supply more safety to isolation structure. A semi-active isolation system in this paper has been proposed to satisfy the requirement. Variable damper is applied to isolation system to vary damping ratio. It was confirmed by numerical analysis that this isolation system has good performance of isolation.

Semi-Active Seismic Isolation System with Controllable Viscous Dampers Using Magneto-Rheological Fluid

Many base-isolated buildings have been constructed using passive isolation systems to reduce response accelerations of superstructures due to earthquakes. The trade-off in the passive systems is that large relative displacements are inevitable to achieve satisfactory reduction in the response accelerations. To solve this trade-off problem, a semi-active seismic isolation system with a controllable viscous damper using a magneto-rheological fluid has been developed. The damping force of the MR damper can easily be changed by altering the magnetic field. However, the MR damper's response to the control signal is delayed, resulting in a negative effect on control performance. To improve this defect, a control law which takes the delay into considerations was proposed for the semi-active seismic isolation system. This paper outlines the results of simulation and excitation tests on the semi-active seismic isolation system with the MR damper using the control law.

Study on Semi-Active Seismic Isolation System with Controllable Friction Dampers Using Hydraulic System Driven by Giant Magnetostrictive Actuators

Study on Semi-Active Seismic Isolation System with Controllable Friction Dampers Using Hydraulic System Driven by Giant Magnetostrictive Actuators

超磁歪アクチュエータ駆動の油圧システムを用いた可変摩擦ダンパによる建築構造物のセミアクティブ免震 ―第1報，可変摩擦ダンパの特性実験―

超磁歪アクチュエータ駆動の油圧システムを用いた可変摩擦ダンパによる建築構造物のセミアクティブ免震 ―第1報，可変摩擦ダンパの特性実験―

430 超磁歪アクチュエータ駆動油圧ポンプを用いた可変摩擦ダンパによるセミアクティブ免震

430 超磁歪アクチュエータ駆動油圧ポンプを用いた可変摩擦ダンパによるセミアクティブ免震

Fundamental Study on the Super-Long-Period Active Isolation System

Background: Since the Hanshin-Awaji Earthquake Disaster, the number of isolated structures has been greatly increased. The natural period of the isolation system is designed around 3s, because the predominate period of observed seismic waves is usually 0.1 to 1s. However, relatively long period seismic waves have been observed in various earthquakes, and the resonances of long-period structures, such as high-rise buildings, during earthquakes have been reported at the same time. Therefore the natural period needs to be extended. When extending the natural period of the isolated structure using rubber bearings, its stiffness needs to be reduced. It is more difficult to extend the natural period of the isolation system than the conventional system because of a buckling problem. Therefore we propose a super-long-period active seismic isolation system as a new method for extending the natural period of the isolated structure. This system consists of rubber bearings and hydraulic actuators. Method of approach: In this study, we designed a control system by using the model matching method. This is one of the classical control system design methods. Additionally we applied a genetic algorithm (GA) to select parameters of a transfer function. Results: The system designed by applying the GA could reduce response acceleration sufficiently compared with the input acceleration. Further waveforms of the response acceleration retain almost straight forwardly, so this indicates good performance of isolation. Therefore, application of super-long-period active isolation is an effective technique to improve the performance of isolation. However, the control forces are big, and the system needs 95.5×106N for the El Centro NS wave as control force. This force is equivalent to 21 actuators that are used in a large shake table, so there are few possibilities to realize active isolation. Conclusion: The required control force of hydraulic actuators is big, although the super-long-period active isolation system possesses good performance of isolation compared with the conventional isolation system. Therefore it is difficult to apply this isolation system to the real structure. However, the problem regarding requirements of the actuator should be solved because of the realization of an active seismic isolation system. Therefore, we will examine for the parameters of the system and semi-active isolation system.

Study on Semi-Active Seismic Isolation System with MR Damper

Study on Semi-Active Seismic Isolation System with MR Damper

438 MRダンパを用いた多自由度構造物に対するセミアクティブ免震

In this paper we design a gain-scheduled (GS) H∞ controller of a semi-active seismic isolation system using a large-scale 40 kN-class magneto-rheological fluid (MR) damper for a four-degree-of-freedom structure. By introducing a fictitious damper model we can transform the bilinear model into a linear parameter varying (LPV) model for which designing of a GS controller based on linear matrix inequalities (LMIs) is available. For verification of the control performance we carry out simulations and experiments for some kind of earthquakes using the 40 kN-class MR damper. In comparison with the skyhook damping control or a passive damper it is verified that the proposed method has good performance.

Semi-Active Seismic Isolation System with Controllable Friction Dampers Using Piezoelectric Actuators

Semi-active seismic isolation systems using controllable friction dampers had been proposed to reduce response accelerations and displacements comparing with those of passive systems, although they had a problem that the dampers might fail to generate damping forces due to malfunctions in strong earthquakes. To solve the problem, a new type of controllable friction damper with a fail-safe mechanism was developed in this study. For the damper, piezoelectric actuators were used to make the mechanism simple. The actuators are compact, and can make quick responses and produce large forces. Simulations and excitation tests were carried out for the semi-active system using the friction dampers, showing good performance in reduction of response acceleration and displacement together with higher reliability comparing with systems using conventional friction dampers.

A comparison of semi-active damping control strategies for vibration isolation of harmonic disturbances

Active vibration isolation systems are less commonly used than passive systems due to their associated cost and power requirements. In principle, semi-active isolation systems can deliver the versatility, adaptability and higher performance of fully active systems for a fraction of the power consumption. Various semi-active control algorithms have been suggested in the past, many of which are of the “on–off” variety. This paper studies the vibration isolation characteristics of four established semi-active damping control strategies, which are based on skyhook control and balance control. A semi-active damper is incorporated into a single-degree-of-freedom (s.d.o.f.) system model subject to base excitation. Its performance is evaluated in terms of the root-mean-square (r.m.s.) acceleration transmissibility, and is compared with those of a passive damper and an ideal skyhook damper. The results show that the semi-active system always provides better isolation at higher frequencies than a conventional passively damped system.

MR流体ダンパを用いたセミアクティブ免震構造(J09-3 振動・システム同定,J09 知的材料・構造システム)

MR流体ダンパを用いたセミアクティブ免震構造(J09-3 振動・システム同定,J09 知的材料・構造システム)

236 セミアクティブ免震のための圧電アクチュエータを用いた可変摩擦ダンパ

A semi-active seismic isolation system using a controllable friction damper was developed to decrease relative displacement between ground and a superstructure. However, if the controller of the controllable friction damper break down, it cannot demonstrate its full performance. A new controllable friction damper using dependable piezoelectric actuators is proposed to slove this problem. This damper has a fail-safe mechanism enabling the system to demonstrate damping effect in case of malfunctions. This paper outlines the results of the characterization experiments of this damper. It also reports the simulation results for the seismic isolation effect and the relative displacement reduction effect of semi-active seismic isolation system using this damper.

642 圧電アクチュエータを用いたセミアクティブ免震構造 : シミュレーションによる検討

In order to decrease a relative displacement between ground and a s superstructure during an earthquake, the semi-active seismic isolation system using a controllable friction damper was developed. However, if the actuators of the controllable friction damper break down when a great earthquake occurs, it can't demonstrate its full performance. In this case, the superstructure acts as a low damping seismic isolation system, and the relative displacement becomes great. In this study, a new controllable friction damper using piezoelectric actuators with a fail-safe mechanism is proposed. This paper outlines the simulation results for the seismic isolation effect, the relative displacement reduction effect, and the performance of the fail-safe mechanism of the new controllable friction damper.

Fuzzy logic control of bridge structures using intelligent semi-active seismic isolation systems

Passive supplemental damping in a seismically isolated structure provides the necessary energy dissipation to limit the isolation system displacement. However, damper forces can become quite large as the passive damping level is increased, resulting in the requirement to transfer large forces at the damper connections to the structure which may be particularly difficult to accommodate in retrofit applications. One method to limit the level of damping force while simultaneously controlling the isolation system displacement is to utilize an intelligent hybrid isolation system containing semi-active dampers in which the damping coeffic ient can be modulated. The effectiveness of such a hybrid seismic isolation system for earthquake hazard mitigation is investigated in this paper. The system is examined through an analytical and computational study of the seismic response of a bridge structure containing a hybrid isolation system consisting of elastomeric bearings and semi-active dampers. Control algorithms for operation of the semi-active dampers are developed based on fuzzy logic control theory. Practical limits on the response of the isolation system are considered and utilized in the evaluation of the control algorithms. The results of the study show that both passive and semi-active hybrid seismic isolation systems consisting of combined base isolation bearings and supplemental energy dissipation devices can be beneficial in reducing the seismic response of structures. These hybrid systems may prevent or significantly reduce structural damage during a seismic event. Furthermore, it is shown that intelligent semi-active seismic isolation systems are capable of controlling the peak deck displacement of bridges, and thus reducing the required length of expansion joints, while simultaneously limiting peak damper forces. Copyright © 1999 John Wiley & Sons, Ltd.

Suboptimal stochastic control for semi-active vibration isolation systems

This paper describes a study of a semi-active vibration isolation system including dry-friction. A semi-active isolation system uses active dampers. The concept of 'active damper' gives rise to a control problem in that the control acts on some multiplicative parameters of the system. The main goal of this work is to find effective semi-active laws for a given performance index. The proposed procedure consists of selecting the semi-active law so that the active damper generates a given active force as long as it is dissipative. This active force is obtained from the study of performances of the associated fully active linear system under different assumptions on the feedbacks available. As an example, the suspension of a truck cab is presented.

Semiactive Seismic Isolation System Using Controllable Friction Damper. 2nd Report. Study of the System with Distributed Controllable Friction Dampers.

Semiactive Seismic Isolation System Using Controllable Friction Damper. 2nd Report. Study of the System with Distributed Controllable Friction Dampers.

Semi-Active Seismic Isolation System Using Controllable Friction Damper : 1st Report, Development of Controllable Friction Damper and Fundamental Study of Semi-Active Control System

In normal base-isolated buildings using passive isolation devices, large horizontal displacements between the ground and the superstructures are inevitable to achieve satisfactory reduction in response accelerations of the superstructures. If energy-absorbing devices of large capacities are used to decrease the relative displacements, the seismic isolation performance will be decreased also. To solve this trade-off problem, a semiactive seismic isolation system using a controllable friction damper was developed, in which the damping force was controlled by varying the pressure between the friction elements. Excitation tests were carried out for a base-isolated single-story building model supported by 4 multistage rubber bearings which had a weight of 5250kg and a horizontal natural period of 1.85s. The controllable friction damper equipped with a hydraulic actuator produced a variable damping force of up to 39.2kN and had a time constant of 20 to 30ms. Through the tests, it was confirmed that while achieving satisfactory reduction in the response acceleration equivalent to that of the normal passive systems, the semi-cative system could decrease the displacement to about 1/2 of that of the passive systems. It was also shown that the variable feedback gain control using fuzzy rules was useful to make the displacement remain within an al1owable range against an excessively strong earthquake.