Towards optimal slip force and stiffness distribution in designing friction dampers

The considerable capacity of friction dampers in energy dissipation makes them a good choice for vibration control of structures. The slip force of friction dampers and also the stiffness of the corresponding bracing system are the major parameters that must be chosen carefully in the design procedure of these dampers. This paper presents an innovative approach to determine these parameters using the data extracted from a series of analyses conducted on three different structures, subjected to five different earthquake records. For this purpose, 900 time-history analyses are conducted. The responses extracted from these analyses are used to compare the effect of different slip forces and to choose the optimum case. Also, a stiffness calibration method is proposed to determine the bracing system stiffness. Finally, two multi-functional optimization methods are introduced to find a single value for optimal slip force. It is shown that between 56 to 74% of the input energy can be dissipated by friction dampers, using this design approach. Additionally, up to 20, 45, 64, and 62% reductions in maximum displacement, velocity, acceleration, and base shear are achieved respectively for the structures studied in this research.