Effect of Bearing Friction on Seismic Performance of Bridges with Massive Piers Isolated by Friction Pendulum Bearings

Abstract

Although seismic isolation is a well-accepted design strategy for bridges to provide structural earthquake resistance, for bridges with massive piers, it may unexpectedly pose an abnormal influence on the seismic response of bridges due to the effect of substructure mass. This study investigates the effects of bearing friction and pier mass on the seismic performance of bridges isolated by friction pendulum bearings (FPBs). Nonlinear time history analysis is conducted to demonstrate the variation of the bridge peak responses with different bearing frictional coefficients and pier mass. The inherent influential mechanism of the frictional coefficient of FPBs is also discussed in the current study. The results of the analysis show that for FPB-isolated bridges with massive piers, the peak base shear forces of piers first decrease and then increase with the increase of the bearing frictional coefficient. Such a phenomenon may be attributed to the fact that the inertia force of the massive piers will be altered by the variation of bearing friction. The outcome of this study provides a useful reference for practical engineering that the seismic base force of massive bridge piers calculated under a specified bearing frictional coefficient may be smaller than the actual response and cause reduced safety to bridges.