Bi-directional coupled effect of friction pendulum system on seismic responses of an isolated bridge

The bi-directional coupled effect of FPS under two horizonta1 orthogonal directional excitations was investigated.Based on a nonlinear numerical model of a typical continuous long span bridge isolated with FPS,its seismic responses taking into account or ignoring the bi-directional coupled interaction of the support restoring force were compared at different levels of parameters,such as,pier height,yield strength of support and support surface radius.The results showed that the bi-directional coupled interaction has considerable effects on the seismic responses of the isolated bridge;if these effects are ignored,the peak support displacements will be greatly underestimated,this situation is harmful to designing an isolated bridge.