PDF | 2 MB - Australian Building Codes Board

Review of AS 1170.4
The earthquake Standard (AS1170.4-1993) is now 14 years old. There have
been complaints about several aspects of the Standard, suggesting that the
existing provisions may no longer meet the needs of the community. The
review of AS1170.4-1993 undertaken by Standards Australia committee BD-
006 identified reform opportunities such as the following:
• international harmonisation of terms, notation, hazard maps and sub
soil descriptions;
• simplified provisions that take advantage of improved understanding of
earthquake actions, the response of different types of structures, and
the potential for damage;
• removal of provisions regarding specific materials, for placement in
appropriate material Standards;
• inclusion of the best available international and local information;
• clarification of the roles of the BCA and the Standard; and
• better integration of the Standard with the BCA.
Review of the 'annual probability of exceedance' table
The proposed new values for the revised annual probability of exceedance for
earthquake were determined from research undertaken by the ABCB in 2006,
including international comparison and benchmarking in comparable socioeconomic
communities. The research considered the values used in countries
such as USA, Canada and New Zealand and was undertaken at the request
of the ABCB's Building Codes Committee.
The review found that when benchmarked against comparable communities,
the current values are too low for building importance level 3 and level 4 and
too high for level 1. It also noted that it is illogical for three different importance
levels to have the same value of 1:500 (i.e. one 'event' in 500 years). A
progressive, stepped approach to the values would more accurately reflect the
appropriate risk to the safety of people in different buildings. The more
important the building, the safer the building should be. The review
recommended a logical, progressive set of values from a lower value for level
1 to a higher value for level 4.
The new values are intrinsically linked to the revision of AS1170.4 as the
development of the Standard has been in tandem with the new exceedence
values. Therefore, there is no option to reference AS11704-2007 in the BCA,
without also updating the Annual Probabilities of Exceedence table.
ABCB Regulation Impact Statement (RIS 2007-03)
8