&lt;title&gt;Semi-active seismic response control of base-isolated building with MR damper&lt;/title&gt;

The experimental analyses of response time and dissipative capability of two prototype magnetorheological semi-active dampers are presented herein. These activities have been conducted during an Italian research project on devices manufactured in Germany. A detailed report of the response time analysis based on experimental data is presented and commented. It is shown how the control delays are strongly dependent on the effectiveness of the electric part of the control hardware, generally being less than 10 ms if special care is paid in designing the whole control chain. The dissipative capacity of the devices is further analyzed under the action of different imposed displacement laws, investigating a large range of displacement amplitudes, frequencies, and feeding currents. Interesting comparisons in terms of energy are finally drawn between magnetorheological damper used in a passive (constant current) and in a semi-active mode (variable current commanded by an energy-based control logic)

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“…Soda et al . experimentally characterize an MR damper fabricated by them resulting to response time of about 300 to 400 ms.…”

Section: Introductionmentioning

confidence: 99%

Promptness and dissipative capacity of MR dampers: Experimental investigations

Caterino

Spizzuoco

Occhiuzzi

2013

Struct. Control Health Monit.

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“…Few papers discuss the response time of MR dampers and published results are also different because of different testing methods and structural parameters of MR dampers. For example, the response time of a MR damper made by Lord Company is between 7.5 ms and 85ms tested by Koo [3], and that of a valve MR damper tested by Milecki is between 30 and 180ms [4], and that of a MR damper fabricated and tested by Soda is about 300 to 400ms [5]. Besides, variation of magnetic field in the damper which directly determines the changing of the damping force is not discussed in these studies.…”

Section: Introductionmentioning

confidence: 89%

Study of the response time of MR dampers

Guan

Guo

2009

SPIE Proceedings

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Response time is an important parameter which determines the applied fields and practical vibration reduction effects of magnetorheological (MR) dampers. However, up to now, only a few papers discuss the test and analysis of response times. In this paper, the response time of a large-scale MR damper at different velocities and currents was firstly tested. Then, the transient magnetic field excited by the time-variant excitation current was simulated by finite element method (FEM). Based on the variation of the shear yield stress of magnetorheological fluids in the gap between the cylinder and the piston, the response time of the MR damper was investigated. Influences of eddy current and excitation current response time on the damper's response were also explored. Results show that by utilizing finite elements method, the calculated average effective shear yield strength can be used to predict the response time of a MR damper. Electromagnetic response is the predominant factor influencing the response time of a MR damper, and reducing eddy currents is the key to accelerate the response of a MR damper. Moreover, influence of eddy currents is much larger under stepping down excitation currents than stepping up currents, and with a same magnitude of step, no matter when the current increases or decreases, the smaller the initial current, the greater the eddy current affects a damper's response and the longer the response time of damping force is. A fast response excitation current may induce large eddy currents which reduce the response of the damper instead.

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“…Results indicate favorable reduction of the superstructure response to both near-and far-field excitations when the control law is applied. Soda et al (2003) carried out large-scale experimental efforts to understand the effectiveness of a 40 kN MR damper that is installed in parallel with several laminar rubber bearings. Results show promising reductions in superstructure response.…”

Section: Review Of Current Literaturementioning

confidence: 99%

A comparative study in the semi-active control of isolated structures

Shook

Lin

et al. 2007

Smart Mater. Struct.

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A comparative analytical and experimental study of several algorithms for the control of seismically excited floor- and base-isolated structures is pursued in the current study. A hybrid isolation system that is comprised of a bidirectional roller–pendulum system (RPS) and augmented by controllable magnetorheological (MR) dampers is proposed to reduce the potential for damage to structures and sensitive equipment. Bidirectional motions are intelligently ameliorated in real time by the modulation of MR damper resistance. A Bouc–Wen model is adopted in numerical and experimental trials to predict behavior of the MR dampers. Three contrasting control techniques are examined. They include neural network control, LQR/clipped optimal control with variable gains and fuzzy logic control. Each control scheme is a candidate for mitigating the response of a superstructure to near- and far-field seismic loadings. Minimization of displacement and acceleration responses of the structure are considered in the formulation of each approach to control. Results of the numerical and large-scale experimental efforts reveal that the response of the isolated structure is effectively alleviated by all of the considered control methods, although they do not perform equally well. The LQR/clipped optimal controller with variable gains is superior to the other controllers in 50% of the investigated cases, while the fuzzy logic controller performs well for earthquakes with large accelerations. Neural network control is found to be effective in minimizing the acceleration of the superstructure that is subject to moderate excitation.

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<title>Semi-active seismic response control of base-isolated building with MR damper</title>

Cited by 9 publications

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Promptness and dissipative capacity of MR dampers: Experimental investigations

Promptness and dissipative capacity of MR dampers: Experimental investigations

Study of the response time of MR dampers

A comparative study in the semi-active control of isolated structures

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