Optimal distribution of seismic upgrading interventions to maximize the expected flow in a road network

The optimal allocation of available economic resources for seismic upgrading of an existing lifeline is dealt with in this paper, with reference to a highway network in which the vulnerable elements are reinforced concrete bridges coinciding with the internal nodes of the network. The objective of the optimization is the expected capacity of the network: i.e., the preventive upgrading interventions are designed, subject to a constraint on the total expenditure, in order to maximize the traffic flow that can be expected to run between a source node and a destination node after an earthquake of given intensity. The expected capacity of each link in the network is defined as an estimated capacity multiplied by the reliability of the end node of the link, in its actual (original or upgraded) condition; the estimated capacity value corresponds to a measured value, or is evaluated by applying a stochastic network loading approach.