Magnetorheological fluid dampers for seismic control

Magnetorheological (MR) fluid dampers have recently emerged as enabling technology for implementing semi-active control in a variety of applications. The successful use of a linear and rotary MR fluid damper in a variety of real-time control applications in the field has recently been demonstrated. Examples of several of these controllable MR fluid actuators, that are now either in commercial production or extended field test, are described herein. This technology is presently being extended to dampers for seismic control applications. Because of their mechanical simplicity, high dynamic range, low power requirements, large force capacity and robustness, magnetorheological (MR) fluid dampers mesh well with application demands and constraints to offer an attractive means of protecting civil infrastructure systems against severe earthquake and wind loading. Following an overview of the current status of MR fluid technology, this paper presents both laboratory and full-scale studies of the efficacy of MR dampers for seismic hazard mitigation.