Optimum Coefficient of Friction in FPS for Base Isolation of Building Frames

Abstract

Base isolation of structures with a friction pendulum system (FPS) has been a topic of great interest for research in the past. The efficiency of the FPS system in isolating a structure depends upon a number of crucial parameters, of which the coefficient of friction plays the most important role. Herein, two methods are presented for determining the optimum value of the dynamic coefficient of friction (μFast), which provides the maximum possible reduction of significant engineering demand parameters (EDP) simultaneously. The optimum value of μFast and the percentage of reduction of EDPs are obtained with respect to the safety gap. The procedures for determining the optimum value of μFast are illustrated with an example of a 10-story building frame base isolated with FPS under both far-field and near-field earthquakes. The results of the study show that the reduction in the number of plastic hinges formed was highly sensitive to the variation of the coefficient of friction: reductions in other EDPs showed mild to moderate sensitivity.