Analysis of base-isolated layer combined by rubber and sliding isolated bearings under vertical stress variation

The horizontal force friction of sliding-isolated bearing is variable when the vertical press change.So if the rubber bearings and the sliding-isolated bearings are used together in parallel in the same base-isolated layer,the characteristic of isolated layer is compex.In this paper the nonlinear finite element program which can analyze the vertical stress variation on sliding isolated bearing is made and introduced.One three-floor frame is analyzed as one example.The dynamical properties of base-isolation layer combined by rubber bearing and sliding-isolated bearing in parallel are anlyzed.The effects of overturning moment and vertical difference deformation on isolation layer are analyzed.The lateral displacement curves of the isolated layer top and the curves of vertical press changing on the sliding-isolated bearing are given on each condition.Analytical results show,that because of the vertical stress variation on sliding isolated bearing,the horizontal dynamic behavior of isolated layer is changed in such layer.This condition should be considered in design.