New Zealand seismic base isolation concepts and their application to nuclear engineering

This paper describes recent New Zealand experience with seismic base isolation, and in particular, the distinguishing feature of the New Zealand system - that of using mechanical energy dissipators to control response. There are presently 22 structures in New Zealand which use base isolation concepts for seismic protection. Nuclear power plants are not used in New Zealand, but the principles adopted for the above buildings and bridge structures are appropriate for nuclear structures and, as shown by use of hypothetical examples, significant benefits can be achieved for these structures also. The most important is a marked reduction for the in-structure acceleration spectra with consequential implications for the enhanced safety of secondary structures and equipment. The paper also reviews the experimental and analytical studies undertaken to validate the technique and addresses the issues of reliability and cost. (orig.)