Beyond Direct Economic Losses: An Integrated Approach to Seismic Retrofit Considering Sustainability and Indirect Losses

Abstract

Seismic retrofit stands as a cost-effective method to strengthen vulnerable buildings and enhance the resilience of earthquake-prone communities. The selection of suitable retrofit strategies is often facilitated by decision-support schemes, which enable the comparison of various options against user-defined criteria (weighted according to stakeholder preferences). Traditional approaches, however, have predominantly emphasised monetary metrics like the costs of retrofit intervention and seismic damage repair, while overlooking other pivotal factors for more informed decision making, including environmental sustainability and indirect economic losses due to downtime. Furthermore, retrofit strategies are rarely designed to achieve the same performance objectives or risk targets before being evaluated via decision-support schemes, possibly leading to misguided comparisons and non-optimal choices. This study addresses these gaps by examining the role of indirect losses on retrofit feasibility and design by incorporating their risk-reduction benefit into conventional life-cycle cost analysis under varying seismic hazard levels. The study also explores prospective pathways for integrating sustainability metrics into decision-making by assessing the carbon footprints of buildings with a life-cycle lens, in addition to the application of carbon taxes. A case study is presented involving an older reinforced concrete (RC) frame, retrofitted using three common strategies: fibre-reinforced polymer wrapping of columns/joints, RC jacketing, and steel jacketing. Finally, the study proposes a practitioner-friendly approach for retrofit design optimisation with minimal iterations. It allows users to specify their desired seismic risk level (in terms of losses) and returns the corresponding nominal performance that must be targeted during the design process.