Optimal Allocation of Resources in Risk Reduction

Existing buildings and facilities in accident-prone sites are sources of risks, from the viewpoints of possible loss of "life and limb", of deterioration of the "quality of life", and of direct and indirect economic losses. Risk reduction is (or should be) a major concern to owners and public authorities, and the available economic resources (usually limited) should be allocated in the most rational (or optimal) way. Several problems arise in this process, like the necessity of taking into account multiple objectives of the optimisation, the "system" behaviour that implies reciprocal influence of several facilities, the fact that the amount of resources is certainly limited but may be initially undefined so that its choice may become part of the optimisation itself, etc. The paper presents the methodology developed over several years (1991-99) to tackle some of these problems, with specific reference to preventive interventions for seismic risk reduction, and some examples of applications to buildings and road networks. The proposed methodology might be extended to other facilities and lifeline networks, and to other hazards (fires, floods, landslides...). Open problems will be pointed out.