On the Value of Forecasting in Cable Ice Risk Management

Abstract This paper addresses the issue of risk management of cable structures with respect to icing events, which may lead to safety issues related to human life, functional disruptions and the associated economic consequences. Emphasis is placed on the value of early warning of icing events, which is based on the monitoring of environmental conditions and short-term forecasting. Decision problems in risk management can be supported by quantifying the value of structural health monitoring (SHM). The approach for the assessment of the value of SHM is based on structural risk assessments together with the Bayesian pre-posterior decision analysis and builds upon the quantification of Value of Information (Vol). Using known probabilistic models, which relate environmental conditions to the events of icing in terms of occurrence, a framework developed earlier is presented for the assessment of the expected value of consequences associated with cable icing events. The consequences are evaluated for different outputs of the probabilistic model to provide a basis for prioritizing risk management decision alternatives. It is shown how forecasting of the environmental characteristics, that is the input to a Bayesian Probabilistic Network model, can be used to update the probability tables of the BPN model and thereby facilitate updating of the ice occurrence probability, which can serve as a decision support tool for the risk management of a cable-supported bridge. The approach is illustrated by an example considering the safety management of a cable-supported bridge subject to the risk of falling ice from the cables. The example shows how the expected value of SHM and forecasting can be assessed, and a sensitivity study concerning the assumptions underlying the consequence modelling is reported.

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