Life-cycle reliability-based system management of structures and networks

A co-ordinated research effort has been initiated by the Authors with the aim of developing life cycle reliability-based methodologies for the management and retrofitting of deteriorating structures and lifelines. As a first step, network systems with vulnerable nodes are considered: specifically, the object of the present paper is the optimal planning of retrofitting interventions on bridges included in a road network, taking into account their deterioration and the limitation of available economic resources. The procedure is illustrated with reference to a 10-node network. It is assumed that the resources available for retrofitting are not sufficient to guarantee the required structural reliability for all bridges throughout the design lifetime: thence the set of retrofitting interventions is sought that maximizes the network reliability (defined as the probability of maintaining at least a connection between an origin and a destination node) under a constraint on the total expenditure. The allocation is performed,by means of a dynamic programming procedure, because exhaustive search would require an unacceptable computer time.