Civil Engineering Reference
In-Depth Information
be risk averse with respect to the consumption rate, and risk neutral with
respect to the discounted life expectancy.
The societal LQI facilitates the comparison of social benefi ts obtained
from different life saving activities/interventions. For instance, public inter-
ventions that increase or maintain
L
are desirable (i.e. d
L
0 under small
changes in
G
and
E
, d
G
and d
E
). Such criteria can be defi ned mathemati-
cally as follows (Nathwani
et al.
1997; Lind 2002):
≥
d
L
L
w
d
G
G
d
E
E
=
+≥
0.
[6.10]
1
−
w
By considering that the life risk due to structural failure in major earth-
quakes is uniformly distributed over age, gender, and economic profi le
within a nation, Rackwitz
et al.
(2005) showed that the increase of the
seismic design level
X
, which affects the initial construction cost d
C
0
(
X
)
(positive) and its associated change in mortality d
μ
mortality
(negative), is desir-
able if:
()
()
−
()
+
()
(
−
exp
exp
γ
γ
t
d
CX
X
exp
exp
η
η
t
d
μ
morta
lity
0
c
c
NG
≤
0
[6.11]
FE
Δ
γ
t
1
d
η
t
1
d
X
c
where
t
represents the service period of the structure;
η
c
is the consumption
growth rate;
N
F
is the number of people in an engineered facility; and
G
Δ
E
is numerically equivalent to the societal value of a statistical life. This
inequality/criterion indicates that the investment for the intervention is less
than or equal to the total gain from the saved lives (in a statistical sense);
thus the equality in Equation (6.11) determines a balanced solution from
the societal point of view. It is interesting to compare the socially acceptable
seismic safety level for structures with the seismic design level dictated
by the current seismic provisions in national design codes. Such an investi-
gation for Canada was carried out by Goda and Hong (2006) (see also
Section 6.4.3).
6.3.4 Risk communication
Risk communication covers a range of activities, aiming at increasing the
public's knowledge and awareness of potential risks. It also facilitates the
participation of the public in risk management and policy-making process.
This includes, for example, warning labels that provide consumer education
about existing hazards, development of publicly accessible databases char-
acterizing hazardous circumstances, and public hearings on risk manage-
ment issues.
Risk communication emerged as an important element of risk manage-
ment of technological issues early in the 1970s. At that time, it was realized
that the majority of the public was not familiar with the nature of risks and
Search WWH ::
Custom Search