Modeling and impact of mechanical faults in MR dampers on the seismic performance of controlled structures

During earthquakes, faults in smart dampers can pose significant challenges to seismic control of structures. Although magnetorheological (MR) dampers are widely used, they remain vulnerable to both mechanical and electrical faults. This study investigates commonly observed defects in MR dampers and develops corresponding mathematical models based on experimental findings. The faulty damper models are then incorporated into a 20-story building to evaluate their effects on the performance of controlled structures and the effectiveness of different control strategies under seismic excitation. Two control algorithms—adaptive and optimal—are implemented, and their performances are evaluated under various fault scenarios. The results demonstrate that oil leakage levels of 5% and 10% considerably degrade damper efficiency. Moreover, defects such as particle trapping and orifice clogging cause approximately 30% and 50% increases in damper force output, respectively. Oil leakage faults result in the largest values of maximum displacements, velocities and base shear forces compared with particle trapping and orifice clogging faults. In contrast, particle trapping and orifice clogging faults lead to higher maximum accelerations. The adverse effects of faulty dampers on control performance depend on their location within the structure. A strong dependence is observed between ground motion characteristics and the resulting structural responses under these two fault types.