Vertical Seismic Responses of Seismically Isolated APR1400 Structures supported by Laminated Rubber Bearings

The low horizontal shear stiffness of the isolator bearing is, typically, accompanied by large lateral displacements in the seismically isolated system. These large lateral displacements might lead to reductions in the vertical stiffness of the elastomeric or lead.rubber bearing (LRB). This paper summarizes the analytical study results performed with APR1400 model isolated with LRBs aimed at investigating the influence of vertical ground motion. Three types of earthquake motions are used as input motion. Floor response spectra are computed at the specific points of the structure to compare the vertical responses of seismically isolated structure to those of fixed base structure. The vertical responses of seismically isolated structure with LRBs might be increased than in the fixed base structure. This fact should be considered in the design stage. The vertical stiffness of the LRB should be reasonably estimated to design a seismically isolated nuclear structure