Emergency Resilience-Driven Retrofit Strategies for Urban Interdependent Infrastructure Systems under Seismic Hazard

Interdependent infrastructure systems play a critical role in the normal operation and postdisaster emergency response in modern cities. However, they are vulnerable to earthquakes throughout their service life, resulting in substantial economic losses and public safety concerns. The threat posed by earthquakes underscores the necessity of implementing risk mitigation strategies. In this paper, an emergency resilience-driven decision model is proposed to address the optimization problem of seismic retrofitting of infrastructure systems. Two types of interdependencies are introduced to reflect the interaction within the infrastructure systems. Then, a resilience metric based on weighted emergency connectivity efficiency is defined to evaluate the ability of a community to provide emergency services under earthquake risks. In addition, a mathematical model and its solution algorithm are developed to maximize emergency resilience benefits while minimizing retrofitting costs, considering resource and probabilistic performance constraints during the emergency response phase. To demonstrate the applicability of the decision model, a case study is conducted on the Centerville community under seismic hazard. The results demonstrate the effectiveness of the decision model in evaluating community emergency resilience and identifying retrofit strategies that align with both resilience benefits and cost optimization criteria. Additionally, the sensitivity analysis results indicate that the intensity of interdependency may significantly affect the optimal seismic retrofit strategies and associated resilience benefits.