Structural Upgrade Selection via Shortest-Path Algorithm Based on Life-Cycle Sustainability Metrics

This paper poses the minimization of sustainability impacts from structural upgrades and repairs as a shortest path problem solved by Dijkstra's algorithm. A case study is presented that evaluates the impact of retrofit and repair options in terms of sustainability metrics and "full-cost price". Alternative bridge seismic retrofits and repairs minimizing negative impacts to the environment, economy, and society are found using the proposed algorithm. The sustainability metrics considered are: carbon dioxide emissions, embodied energy, downtime, and monetary costs. In addition to seeking the minimum expected value, the associated variance - as well as the shortest path for the uncertainty of each of these measures - is found. Results highlight impacts of traditional engineering decisions on the environment and society and display uncertainty variations associated with sustainability metrics. This framework is anticipated to help guide the selection of sustainable structural upgrades and, in the future, facilitate accommodation of stakeholder preferences regarding target sustainability measures.