Optimal design of rotational friction dampers for improving seismic performance of inelastic structures

Rotational friction dampers (RFDs) have been proposed as one of the passive control devices in order to enhance the seismic performance of inelastic structures and dissipate the input energy of earthquakes through friction in their rotating plates. The efficiency, performance and design of an RFD strongly depend on its frictional moment and the length of its vertical rigid beam. Hence, the main contribution of this study is to propose an optimal design of the RFD for the seismic vibration control of an inelastic single-story steel moment-resisting frame (SMRF). For achieving this purpose, the parameters of the RFD subjected to an artificial earthquake were first optimized through minimizing the ratio of seismic input energy to dissipated the energy in the RFD. Modeling results show that the optimized RFD is able to give an average reduction of 54%, 75% and 97% versus the structure without an RFD in terms of the maximum and residual roof displacements and the cumulative hysteresis energy of the SMRF, respectively. Then, the seismic performance of the SMRF equipped with the optimized RFD was assessed subjected to four historic earthquake records. The results indicate that the optimal RFD-equipped structure subjected to the historic earthquakes exhibits a better seismic performance in all measures compared with the uncontrolled structure.