Socio-economically sustainable civil engineering infrastructures by optimization

Sustainability is an important requirement for civil engineering infrastructures, technically and financially. The financial aspects are discussed. It is proposed to select a design and maintenance strategy where structures are systematically renewed by reconstruction or repair. An appropriate objective function for cost-benefit analyses based on a renewal model is established. An intergenerationally acceptable discounting scheme is proposed. As infrastructures also involve risk to human life and limb a socio-economic acceptability criterion to be added as a constraint to cost-benefit analyses is derived. Various renewal models for deteriorating structures including multiple failure modes are discussed. The paper includes various examples illustrating the developed theory.