Experimental study of sliding friction damper with composite materials for earthquake resistant structures

This paper presents the experimental results from 62 tests on five non-metallic friction pads that could be potentially used in friction dampers for minimizing earthquake-induced damage in buildings. The friction pads are composed of fibres and organic and inorganic fillers bounded together by phenolic resins and have never been explored for potential use in supplemental damping devices. A full-scale sliding friction damper prototype was developed for this purpose. Parameters examined as part of the experimental program include the applied pressure level to control the sliding force, the imposed loading protocol and the associated loading rate. The experimental results reveal that two of the explored friction pads exhibit similar static and dynamic friction coefficients, which are on the order of 0.2 and 0.3 regardless of the examined pressure level and loading protocol. These values are fairly invariant with respect to temperature and to sliding velocity as long as it is larger than 10 mm/s. While surface wear is the primary damage mechanism of the two most prominent friction pads, their immediate replacement is not imperative in typical earthquake mainshock-aftershock sequences. Moreover, loss of bolt pretension in the friction damper was practically negligible during the same loading sequences.