Sustainability-based bi-objective optimization for seismic retrofit of bridge networks considering risk attitudes

Optimal retrofit scheduling for civil infrastructure is a complex process that allows for the inclusion of budget constraints as well as multiple conflicting objectives involving intervention costs and structural performance. Effective retrofit planning is integral to maintaining and improving the structural seismic performance of highway bridge networks. A comprehensive management framework that utilizes a sustainability- based bi-objective optimization procedure to determine optimum pre-earthquake retrofit plans for bridge networks considering the attitude of the decision maker is established within this paper. The uncertainties accounted for within this approach include those associated with seismic hazard and structural vulnerability. Additionally, the effects of the risk attitudes of decision makers are reflected in the formulation of a utility function corresponding to expected seismic monetary losses. Furthermore, time effects on structural seismic performance are incorporated into the approach. The set of Pareto optimal solutions describing retrofit planning is obtained by employing Genetic Algorithms within a multi-criteria optimization procedure. The methodology is illustrated on several representative highway bridge networks, including series, parallel, and series-parallel systems.