Civil Engineering Reference
In-Depth Information
0.5
0.4
PML
Risk curve
0.3
0.2
NEL
0.1
0.0
27.10
Comparison of various risk indices based on recurrence time of
475 years.
estimated seismic risk level by the integrated risk curves are smaller than
PML
475
. This is because that City C is located in the region where the seismic
hazard is very high. It is noted that values of NEL
475
is approximately a
third of PML
475
. It is denoted that since the load-carrying capacity ratio
Q
u
/
Q
un
of buildings and soil conditions at six cities are the same in order to
simplify this case study, loss ratios of all buildings such as NEL and PML
are only dependent on the seismic intensity and characteristics of the city
locations. Therefore, one clearly understands that City C exhibits extremely
high risk because it is located near the source of strong earthquakes (Tokai
region in the central Japan) with high probability. Such comparative analy-
sis results provide valuable information to both expert engineers/risk ana-
lysts and non-expert investors and insurers. For example, results shown in
Fig. 27.10 render a clear message to business managers about the extent of
seismic risk at stake in monetary terms.
27.3.4 Comparative risk assessment of reinforced concrete
buildings with different capacities
The fi nal case study is related to seismic risk assessment of fi ve-story
reinforced concrete buildings with different structural capacity. The aim of
this investigation is to evaluate the infl uence of the structural performance
of the buildings on the risk assessment. Such analysis results are useful as
they clearly show the trade-off between seismic code compliance level and
the potential earthquake risk. Moreover, the seismic code compliance level
has a direct infl uence on initial construction cost (different sectional sizes),
and thus is related to cost-benefi t analysis or optimum seismic design of
buildings (Rosenblueth 1976; Rackwitz 2000). For such purposes, ratios of
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