Difficulties in applying the seismic design provisions of the
NZ Standard Code of Practice for General Structural Design and Design Loadings for Buildings, NZS 4203:1976, to multi-component petrochemical facilities lead to the preparation of the document: Seismic Design of Petrochemical Plants - Volume 1: Recommendations and Volume 2: Commentary. This paper explains the basis of that document. The philosophy
that is used provides for a consistent level of earthquake protection
to the various components of a petrochemical facility according to the importance of the component and the potential hazard associated with its failure. This is achieved by establishing design load levels based on assessed seismic risk and structure reliability. An important part of the philosophy is the minimising of seismic risk by the elimination or modification of potentially hazardous situations at the conceptual design stage. The derivation of basic seismic design coefficients from a
seismicity study of New Zealand is described and the analysis and
detailing procedures adopted in the Recommendations for structures and equipment in petrochemical facilities are discussed. Particular attention is given to explaining the application of capacity design principles to ductile structural forms.