Influence of the bilateral coupled effect of the bearing on the seismic response of the structure isolated by friction pendulum system

A comparative study on the seismic response of the structure isolated by the friction pendulum system under unilateral and bilateral ground motions is conducted in this paper. It is found that, under the bilateral ground motions, the accelerations of the superstructure in X and Y directions are reduced, however, the displacements of the bearing in X and Y directions are increased. The methods according to the NEHRP Guidelines for the Seismic Rehabilitation of Buildings FEMA-273 and the Code for Seismic Design of Buildings of China (GB50011-2001) to determine the peak displacement of the bearing in any direction considering the bilateral coupled effect of the bearing are discussed. The difference of the methods to determine the peak displacement of the bearing between FEMA-273 and GB50011-2001 is insignificant. The peak displacement of the bearing under bilateral ground motions are obviously larger than that under unilateral excitation, so that in order to determine the peak displacement of the bearing, the bilateral coupled effect of the bearing under the bilateral ground motions should be considered.