The viability of exploiting magnetorheological (MR) dampers for earthquake protection of structures has been investigated. A MR damper requires low electrical power and is inherently fail-safe, as it reverts to standard passive viscous damper, in case of electric failure. Moreover, a variety of techniques and control algorithms have been applied over years to control the structural seismic response. Those include some active mass dampers, friction dampers and resorting to variable stiffness control. Controlled friction forces can be effectively used to limit the building response to the earthquake. Friction pendulum systems are commonly used to provide base isolation to seismic excitation. MR dampers can be suitably integrated in that application. They exhibit a low time constant (8 to 25ms), and thus phase lag problems for typical seismic inputs are avoided in control. A key additional feature is that they can operate either as an active or passive system. Even in case of poor or abnormal operating condition in active mode, they provide damping, by resorting to passive one. Usually, the electric current input is quite low, if compared to some other actuators widely applied in mechatronics, and this makes them suitable devices to provide semi-active control forces to counteract lateral ground excitation. MR can be even operated by battery, and thus they are highly preferable during the earthquake, as main power feeding is often inhibited. Their mechanical system is highly reliable, as it has been already tested in the car industry, where MR damper-based suspensions have been successfully applied, since some years, on high-class and highperformance vehicles. To improve the performance of this system and to better control its scalability over buildings of different size, a possible approach consists in implementing a robust control strategy in the MR damper set-up, being based on variable structure control theory. It needs a deep investigation about requirements and functions of the MR applied to the building under design. Therefore, resorting to the MBSE in functional and physical modeling looks appropriate. An example of functional model of the response of a multi-store building has been developed. It leads to define the system functional architecture, including three blocks. Numerical modeling and simulations allow then investigating the system performance for given set of MR damper parameters. However, to completely verify requirements and validate that device some experimental tests have been performed. A deep exploration about the technology most suitable to apply the control in test case has been driven. by a systematic analysis of technological solutions currently available in connection to features of the system behavior. The whole investigation included three main systems. They differ in terms of variable level of sophistication. A pure building base isolation has been compared to cases of isolation with adaptive damping, first, and adaptive damping with spring effect cancellation, in a second step. The MR damper characteristics have been experimentally identified. In terms of motion, the three systems tested correspond to base sliding, sliding with adaptive damping, and adaptive damping with spring cancellation. A base clearance is always included to introduce a passive protection system, as required by application. In presence of a peak acceleration in input of 0.68g, the drift at one-third height is reduced by a factor of three, compared to pure passive system operation. The trade-off analysis demonstrates that base isolation is somehow effective, if the earthquake excitation exhibits a small amplitude. As the control strategy refines and increases the intelligence content, the system performance improves. The control strategy exploiting an adaptive damping with spring cancellation effect, applied to the sliding base system, reaches up to 80% reduction in drift.

Magnetorheological Dampers for Earthquake Mitigation: A System Engineering Perspective / Guglielmino, Emanuele; DI MAIO, Marco; Brusa, Eugenio; Gastaldi, Chiara. - ELETTRONICO. - IEEE Catalog Number: CFP24SYM-ART:(2024), pp. 1-2. (Intervento presentato al convegno 2024 IEEE International Symposium on Systems Engineering tenutosi a Perugia, Italy nel 15-18 October, 2024,) [10.1109/ISSE63315.2024.10741102].

Magnetorheological Dampers for Earthquake Mitigation: A System Engineering Perspective

Eugenio BRUSA;Chiara GASTALDI
2024

Abstract

The viability of exploiting magnetorheological (MR) dampers for earthquake protection of structures has been investigated. A MR damper requires low electrical power and is inherently fail-safe, as it reverts to standard passive viscous damper, in case of electric failure. Moreover, a variety of techniques and control algorithms have been applied over years to control the structural seismic response. Those include some active mass dampers, friction dampers and resorting to variable stiffness control. Controlled friction forces can be effectively used to limit the building response to the earthquake. Friction pendulum systems are commonly used to provide base isolation to seismic excitation. MR dampers can be suitably integrated in that application. They exhibit a low time constant (8 to 25ms), and thus phase lag problems for typical seismic inputs are avoided in control. A key additional feature is that they can operate either as an active or passive system. Even in case of poor or abnormal operating condition in active mode, they provide damping, by resorting to passive one. Usually, the electric current input is quite low, if compared to some other actuators widely applied in mechatronics, and this makes them suitable devices to provide semi-active control forces to counteract lateral ground excitation. MR can be even operated by battery, and thus they are highly preferable during the earthquake, as main power feeding is often inhibited. Their mechanical system is highly reliable, as it has been already tested in the car industry, where MR damper-based suspensions have been successfully applied, since some years, on high-class and highperformance vehicles. To improve the performance of this system and to better control its scalability over buildings of different size, a possible approach consists in implementing a robust control strategy in the MR damper set-up, being based on variable structure control theory. It needs a deep investigation about requirements and functions of the MR applied to the building under design. Therefore, resorting to the MBSE in functional and physical modeling looks appropriate. An example of functional model of the response of a multi-store building has been developed. It leads to define the system functional architecture, including three blocks. Numerical modeling and simulations allow then investigating the system performance for given set of MR damper parameters. However, to completely verify requirements and validate that device some experimental tests have been performed. A deep exploration about the technology most suitable to apply the control in test case has been driven. by a systematic analysis of technological solutions currently available in connection to features of the system behavior. The whole investigation included three main systems. They differ in terms of variable level of sophistication. A pure building base isolation has been compared to cases of isolation with adaptive damping, first, and adaptive damping with spring effect cancellation, in a second step. The MR damper characteristics have been experimentally identified. In terms of motion, the three systems tested correspond to base sliding, sliding with adaptive damping, and adaptive damping with spring cancellation. A base clearance is always included to introduce a passive protection system, as required by application. In presence of a peak acceleration in input of 0.68g, the drift at one-third height is reduced by a factor of three, compared to pure passive system operation. The trade-off analysis demonstrates that base isolation is somehow effective, if the earthquake excitation exhibits a small amplitude. As the control strategy refines and increases the intelligence content, the system performance improves. The control strategy exploiting an adaptive damping with spring cancellation effect, applied to the sliding base system, reaches up to 80% reduction in drift.
2024
979-8-3503-5372-3
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2996218
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