Effect of seismic hazard definition on isolation-system displacements in nuclear power plants

The key results of the study, which are broadly applicable to sites of lower seismic hazard and other nonlinear bearings (e.g., the lead-rubber bearing), are: (1) the seismic hazard definition should account for differences between the amplitude of ground motions in the principal horizontal directions, (2) the displacement capacity of an NPP isolation system is controlled by the 90th percentile BDB shaking displacement, for a given hazard definition, and (3) the coefficient of friction at the sliding surface of a single-concave FP bearing should be defined using a p-T-v model because the standard Coulomb model may be inadequate for high values of axial pressure and nominal coefficient of sliding friction.