Structural vulnerability analysis of civil infrastructure facing seismic hazards - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 223

one starts with vulnerable failure scenarios and looks for the probability of
actions that will cause those failure scenarios. Ultimately, both methods lead
to an estimation of risk of failure but the latter has the potential to avoid
catastrophic failures due to actions that would have otherwise been ignored.
With increasing complexity and interdependence of infrastructures, anal-
ysis of risk for any one utility (e.g. water supply system or energy supply
network) can no longer be done in isolation. Damage to one infrastructure
has the potential to affect other infrastructures. During an earthquake many
infrastructures are affected at the same time and generally each one of
these at several locations. Thus approaches to analyse the consequences of
a hazard irrespective of their chance will be increasingly used.

8.7 Conclusions

Vulnerability analysis is concerned with the form of the system which leads
to an identifi cation of vulnerable failure scenarios. Some of these failure
scenarios may have the potential to cause disproportionate failure due to
one or more actions. Each possible action may contribute to the realization
of different failure scenarios. In the approach described here, an assessment
of the likelihood of a failure event is initially kept independent of the
hazards and then combined with the assessment of the hazards. The conse-
quence of a failure scenario and the support for this scenario give a measure
of the risk it poses to the system. Risks due to different failure scenarios
can be compared and appropriate measures taken to reduce the risks to an
acceptable level. Some failure scenarios may be managed better by improv-
ing the form while others might require appropriate measures to limit the
likelihood of actions.

8.8 References

Agarwal, J. (2001) Vulnerability analysis of 3D structures, Proceedings of
ICOSSAR'01 , California.
Agarwal, J. (2005) Managing structural risk, In: G. Augusti, G.I. Schueller, M. Ciam-
poli (Eds), Safety and Reliability of Engineering Systems and Structures , Proceed-
ings of ICOSSAR 2005 Rome, pp 1793-1799.
Agarwal, J., Blockley, D.I., Woodman, N.J. (2001a) Vulnerability of 3D trusses, Struc-
tural Safety , 23 , 203-220.
Agarwal, J., Blockley, D.I., Woodman, N.J. (2001b) Vulnerability of systems, Civil
Engrg Env Systems , 18 , 141-165.
Agarwal, J., Blockley, D.I., Woodman, N.J. (2003) Vulnerability of structural systems,
J Structural Safety , 25 , 263-286.
Agarwal, J., Liu, M., Blockley, D.I. (2011) A systems approach to vulnerability
assessment, In: B.M. Ayyub (Ed), Vulnerability, Uncertainty and Risk , Proceedings
of the International Conference on Vulnerability, Risk Analysis and Management
(ICVRAM), Washington. ASCE.