This lecture presents background information on the philosophical framework within which some of the more important decisions were made
and which led to the final proposal for the seismic provisions for New Zealand NZS 4203 "Code of Practice for General Structural Design and Design Loadings". Aspects of ductility and seismic design coefficients for various types of structure are considered with illustrations to
show how the new code covers the necessary design requirements. The design principles lying behind the code requirements are discussed, particularly for concrete frame and shear wall type structures. The interaction between earthquake motion of the subsoil and motion of the structure is also discussed. A number on unresolved problems are highlighted, particularly those concerned with short period structures,
long acceleration seismic pulses, the damping-amplification relationship and mathematical modelling. Overseas codes are compared showing latest developments and illustrating the wide range of values used for the basic requirement. The lecture concludes with a consideration of likely future development and the manner in which the code is likely to be updated in the future.