Analysis of single-degree-of-freedom systems containing multifunctional friction damper

Friction dampers are one type of energy dissipation devices that are able to forms an efficient seismic protection system for seismic structures. Nevertheless, traditional friction dampers can only be designed under a target earthquake of a given intensity. Complied with the current design code, this target earthquake usually has an intensity of the return period of 475 years. Consequently, traditional friction dampers may function well under earthquakes with the intended design level, but may not be functional for earthquakes with lower intensities. This situation may pose a problem particularly for some functional facilities, which usually contain vibration-sensitive equipment that is vulnerable to earthquakes with moderate intensities. In order to satisfy the aforementioned multiple functional demands, this paper investigates the possible use of a novel multi-functional friction damper (MFD). Different from traditional friction dampers, the MFD has two-stage slip forces that can be activated in a moderate and a strong seismic level, respectively. The theory of the MFD and the formulation of a SDOF system with the MFD are both given in this paper. The results of the numerical simulation reveals that the MFD is able to reduce the structural responses under strong and moderate ground motions, simultaneously. In addition, the MFD is also more effective at reducing the structural responses under a moderate earthquake, as compared to the response result from a traditional friction damper.