Optimal allocation of resources for life-cycle management of structures and highway networks

In recent years, researches on reduction of the probability of damage to existing structures taking account of possible limitations of available resources, have developed essentially along two lines: a) life-cycle reliability-based management of deteriorating structures; b) planning of preventive interventions to reduce the expected consequences of accidental events, and in particular, of earthquakes. In the present paper, the two approaches are combined, and a procedure is presented for the optimal planning of retrofitting interventions on bridges located in an existing road network, assuming that the available economic resources are limited, and taking account that the vulnerable structures deteriorate with time. Since the structures are essential parts of a lifeline network, the definition of risk and the optimization procedure must also include system effects. In the optimization process, several objectives might be considered: in this paper, attention is focused on the reliability of the network (defined as the probability of maintaining connectivity). A specific example of application illustrates the procedure.