Design implications for structures within the Adelaide CBD arising from changes to the subsoil classification system In As 1170.4

This paper discusses the subsoil classification system adopted by the updated earthquake design standard AS 1170.4–2007 and its application to the Adelaide Region. It will be seen that the new system models Adelaide as a “deep stiff” soil profile, with significantly higher site amplification factors than those adopted by the 1993 edition of the standard, particularly for structures with long periods.

The consequence of this change for seismic design within the Adelaide CBD will be briefly explored by comparing design base shears calculated using both the 1993 and 2007 editions of the standard. It will be seen that design base shears calculated using the revised standard are significantly higher for typical structures within the Adelaide CBD.