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including Hong Kong are considering introducing seismic design where previously there was none.
Table 1 provides a brief summary of key dates when seismic design was officially introduced for some
areas of low to moderate seismic risk.
TABLE 1
DATES SEISMIC DESIGN INTRODUCED
Location
Boston USA i
Australia "
Canada J
China 4
New York USA '
Date
1975
1979
1985
1990
1995
Comments
After 7 magnitude earthquake in Meckering 1968
Seismic provisions since 1953
Official code 1974 but seismic design not required for intensity less than 7
Classified zone 2 on map in 1982
1. Nordensen(1989) 2.Bubb(1998) 3. Heidebrecht(1998) 4.Hu(1993)
It is probable that seismic design was carried out for some government buildings prior to legislation
being introduced. For example the author earned out the design for a new replacement school in South
Africa at Tulbach near Cape Town incorporating seismic provisions in 1972 following an earthquake
estimated to be 6.3 on the Richter scale on 29 th September 1969. Similarly hi Hong Kong there are
some buildings which have incorporated seismic design and details even though there is no statutory or
code requirement to do so. From the above it can be seen that earthquake design in intra-plate areas is
relatively recent
Existing seismic knowledge in Hong Kong
In HK at present there are no requirements for buildings to be designed for seismic loads. Civil
engineering structures, however, including bridges and railway stations have been routinely designed
for seismic forces since at least 1983, (Civil Engineering Manual Chapter 4 1983). The Structures
Design Manual for Highways and Railways (HKSDM) was published in 1993 (Highways Department
of HK. 1993) and became more accessible to structural engineers designing buildings from May 1994
when it was referenced to in PNAP 115 (Buildings Department HKSAR 1994). The nominal seismic
load in the HKSDM is .05 times the mass, to which is applied as a static force with a dead load factor
of 1.4 giving an equivalent to an ultimate acceleration of 0.07g. No consideration of structural form or
soil conditions is required.
In HK seismic design knowledge and awareness of structural engineers has increased through a
number of initiatives by Government, Universities and others since tie early 1990's. This knowledge
has also increased because there have been many designs carried out by HK structural engineers for
developments in China where seismic design is required. In some ways this may not be an advantage
since conceptually there are differences in the Chinese approach when compared to some of the
seismic codes in other countries. Further Chinese design institutes frequently cany out the detailed
design of a building so some of the detailed provisions are not so well known in HK. In 2002 the
Buildings Department invited tenders to study the seismic effects on buildings in HK and so it is
possible that a seismic code will be developed within the foreseeable future.
The major seismic regions of the world such as California, Japan, China, Taiwan and New Zealand
have long had seismic codes that are well established. Many of the HK local practicing structural
engineers who have had their education in these countries understand seismic codes but have not