A study of a variable friction damper with a stepped force characteristic

Using damping devices is a well known way to improve response of buildings to seismic motions. Addition of dampers to base isolation systems aimed to limit large base displacements has been proved as an effective solution. Passive variable friction dampers can be also applied in order to get structural behaviour similar to that with active controlled systems. This paper is an extension of a previous study performed on a variable friction damper. The current research is focused on a variable friction damper having a stepped friction force characteristic. It is shown that the proposed stepped force characteristic allows better satisfaction of the damper to the requirements of semi-passive control. A principal theoretical model for choice of design parameters of the damper is proposed. In order to verify the properties of the variable friction damper, a laboratory experimental model has been designed and tested using a small-scale laboratory shaking table. It is shown that the proposed damper enables to get a desired variable force-displacement characteristic. The dynamic test has demonstrated that the parameters of the damper are in good correlation with the theoretically obtained results.