A constant friction coefficient model for concave friction bearings

Abstract

This paper develops a constant friction coefficient model that best represents a velocity-dependent friction model for predicting structural response of buildings isolated with concave friction bearings. To achieve this goal, the effect of friction model on structural response of three hypothetical isolated buildings with different number of stories subjected to different earthquake scenarios was numerically investigated. The structural numerical models of the isolated buildings were developed in OpenSees with superstructure is represented by a shear frame model and isolation system using single friction pendulum bearings is modeled by a 3-D friction pendulum bearing element which accepts different friction models. The numerical models were subjected to 30 pairs of ground motions, representing service earthquake level, design basic earthquake level and maximum considered earthquake level at a strong seismic activity area in the world. The investigation reveals that friction coefficient models significantly affect the structural response and there is no constant friction coefficient model that simultaneously best predicts isolation system response and superstructure response. The constant friction coefficient that best predicts isolation system response produces a large error on prediction of superstructure response and vice versa. Based on the numerical results, a constant friction coefficient model for different criteria was developed.
 Keywords:
 friction coefficient model; friction bearing; isolation system; earthquake response; time-history analysis.