Optimal planning of retrofitting interventions on bridges in a highway network

The aim of the co-ordinated research effort initiated by the Authors consists in 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. The object of this paper is the optimal planning of retrofitting interventions on bridges included in a highway 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 service life: thence the set of retrofitting interventions is sought that maximizes the network reliability (defined as the probability of maintaining connectivity) under a constraint on the total expenditure. The allocation is performed by means of a dynamic programming procedure.