Geoscience Reference
In-Depth Information
In this paper, the general formulation for risk assessment of transportation system that
considers the uncertainty of the various parameters is presented. A method for including
thecorrelationsofgroundmotionandbridgedamageisdescribedbasedonrecentdevel-
opmentsbyLeeandKiremidjian(2006)andefficientmethodsforcomputationoftherisk
function with the various uncertainties is discussed. The various methods are illustrated
through applications to sub-networks of the transportation systems of the San Francisco
BayArea.Estimatesofthedirectlossesandfunctionalitylossesareobtainedforthestudy
regionandthecontributionofeachtypeoflossisquantifiedtodetermineitsimportance.
2. Overview of transportation risk assessment
The performance of transportation networks when subjected to earthquakes is highly
dependent on the performance of their components. These components are subject to
different ground motions and ground deformations that cause various levels of damage.
It is the goal of this paper to present a formulation for seismic risk analysis not only
due to structural loss, but also, due to post-event network disruption, both expressed in
monetary units.
Therearethreemaincomponentsintheriskformulationpresentedinthispaper.Thefirst
partconsistsoftheestimationofthestructuraldamageandriskanalysisatthecomponent
level(bridges).Inthesecondpartwecomputenetworkfunctionalityloss.Inthelastpart,
weaggregatethelossesduetostructuraldamageandnetworkdisruptioninordertodefine
the total loss.
2.1. COMPONENT RISKANALYSIS
Probabilistic methods are particularly suitable for risk assessment and have been used
extensivelyforthatpurpose.Theresultspresentedinthispaperdrawonthemethodology
proposed by the Pacific Earthquake Engineering Research Center (PEER). The PEER
equation isgiven asfollows:
P
[
DV
>
d
v
]
=
dF
DV
|
DM
dF
DM
|
EDP
dF
EDP
|
IM
dF
IM
(19.1)
where
DV
isthe decision variable
DM
is the damage measure
EDP
is the engineering demand parameter
IM
is the intensitymeasure
F
isthe cumulative distributionof the random variable
InEquation19.1theMarkovianassumptionismadewhenevaluatingthevariouscompo-
nents of the integral, i.e. the dependence among variables is carried only to the previous
