Floor response spectra of a partially embedded seismically isolated nuclear plant

•Finite element SSI analysis of a realistic model of a base isolated nuclear power plant.•Base rocking excitation of partially embedded seismically isolated buildings is investigated.•Evidence of possible amplification of the non-isolated modes׳ response.

This paper deals with the effects of foundation embedment on the floor response spectra of big base isolated structures such as nuclear power plants. Analyses of a finite element model, representative of a real nuclear power plant, have been carried out. It has been demonstrated that, in agreement with previous work, base rocking excitation, induced by soil–structure interaction, may amplify the non-isolated modes׳ response and thus it must not be overlooked.