Preventive measures for reducing the seismic risk of bridges

With specific reference to the seismic reliability of existing bridges and highway networks, the design of preventive upgrading interventions is discussed. First, the results are presented of a numerical analysis of the seismic response of multispan r.c. girder bridges, aimed at evaluating the efficiency of different upgrading techniques. Next, a procedure is illustrated for assigning priorities among the bridges included in a highway network, allocating the available resources in such a way that some appropriate objective function is maximized. Three possible objective functions are considered, namely the probability of maintaining a connection between a source and a destination node (reliability of the network), the ratio between the increase of reliability and the time employed (time-efficiency of the interventions) and the out-of-service time of the network in case of a severe earthquake.