Abstract:Modeling method of the restrainers was proposed for the seismic analysis of the tall pier pile foundations rocking isolated system. Effect of the restrainer on the rocking response of a railway tall pier was investigated through nonlinear time history analysis by inputting three strong ground motions. The displacement at the top and the moment at the bottom of the pier are discussed as functions of the initial gap and yielding force of the restrainer. The results show that the restrainer decreases the displacement at pier top, while it increases the base moment. The initial gap of restrainer has greater effect on the top displacement than the base moment. It is also observed that the yield force of restrainer affects the rocking response of the tall pier pile foundations isolated system significantly.