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Introduction: The incremental research progress on Magneto-Rheological (MR) damper and its response motivated many researchers and engineers to focus on this topic in the last decade. Methods: MR damper is classified as a semi-active vibration controlling device owing to its mechanical simplicity, low power usage, large response reduction, perfect damping mechanism, good stability, quick reaction time and robust interface. Results: In the current investigation, experimental studies were performed for the design, development, and testing of a new type of MR damper. A proposed approach was adopted for the magnetic generation using multi-coils to produce more shear force in the flow gap. The study investigates time history responses of the proposed system under an array of strong ground motions at both element and structure levels. Numerical hybrid simulation using OpenSees has also been carried out on a building structure to show the effectiveness of the new device. Conclusion: The performance of the investigated structure equipped with the proposed system indicates a large reduction in displacement and an increase in damping force under major seismic events.

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Magnetorheological (MR) fluids with excellent rheological characteristics are capable of exhibiting very quick responses to control vibrations in machines and structures under seismic excitations. The damping properties of MR fluids can be controlled by varying the externally applied magnetic field and current to the fluid. In the present work, MR fluids with nanoscale suspensions were used to eliminate the need of additives and to minimize the settling. The resultant suspensions exhibit good magnetic behavior under damper with off-state and on-state rheology using cyclic load test. The result also showed that the maximum damping force of 2 kN (off-state) and 3.52 kN (on-state) was observed for the MR fluid containing 20 % iron particles in silicone oil. Additionally, the behavior of the MR damper on a reinforced cement concrete (RCC) frame subjected to cyclic loading was studied. To determine the efficiency of the MR damper, an RCC frame was casted and tested with and without damper. The results show that the incorporation of the MR damper reduced the displacement by 49 % and an increase in load carrying capacity of 55 % was attained compared with the RCC frame without damper.

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